modul kelanan jantung bwaan

7/27/2019 Modul Kelanan Jantung Bwaan

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REPORTOF

3rd MODULScenario 2

System Cardiovaskular

1A Group

Maria Ulfah (1102090049) Irfan Thamrin (1102090056) Rizki Rahmadhan (1102090063) Akhmad Edwin Indra Pratama (1102090064) Fakhrurrazi (1102090065) Muh. Fadly Aditya (1102090070) Muhammad Assadul Malik (1102090072) Inna Mthmainnah Musa (1102090084) Andi Firman Mubarak (1102090088) Ainun Martoni (1102090093) Andi Fajar Apriani (1102090106) Dzul Ikram (1102090108) Zarah Alifani Dzulhijjah (1102090115) Sigit Dwi Pramono (1102090133) Andi Anugrah Suci (1102090142) Nur Sabriany Lihawa (1102090156)

Medical FacultyMoslem University of Indonesian

2010


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A. SCENARIOA ten year old girl comes with her lips and fingers blue. This has happened since she

was a baby.This worsens when she cries or plays. She often have to sit on her knees

when she is tired playing. Physical examination shows small and skinny appearance.

Cyanosis appears on her lips,end of her tongue, her fingers and toes. Pulse and bloodpressure are normal. Thorax examination reveals right ventricle activity increases,

followed by thrill at LSB 3. Heart sound 1 and 2 are pure, intensity increases. Systolic

ejection murmur (degree 3/6 p.m LSB 4), is found. Femoral artery palpation is

normal. Shes got drum stick fingers.

B. ANATOMYPosition

Left : linea medioclavicularis

sinistra

Right : linea parasternalis dextra

Top : intercostal II

Bottom : intercostal V


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Morphology

ApexA part of left ventricle

Position :-intercostalis space 5 kiri


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- 9 cm from left mediana line

- 2 fingers left medioclavicularis line in medial site

BasisTop : craniodorsal in the left orientationBuilt by:

- some parts of left and right atrium

- proximal part of large blood vessels

sternocostalis facies sinister diaphragmatica facies

C. FISIOLOGICIRCUIT


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The left heart and right heart have different functions. The left heart and the

systemic arteries, capillaries, and veins are collectively called the systemic

circulation. The left ventricle pumps blood to all organs of the body except the lungs.

The right heart and the pulmonary arteries, capillaries, and veins are collectively

called the pulmonary circulation. The right ventricle pumps blood to the lungs. Theleft heart and right heart function in series so that blood is pumped sequentially

from the left heart to the systemic circulation, to the right heart, to the pulmonary

circulation, and then back to the left. The rate at which blood is pumped from either

ventricle is called the cardiac output. Because the two sides of the heart operate in

series, the cardiac output of the left ventricle equals the cardiac output of the right

ventricle in the steady state. The rate at which blood is returned to the atria from

the veins is called the venous return. Again, because the left heart and the right

heart operate in series, venous return to the left heart equals venous return to the

right heart in the steady state. Finally, in the steady state, cardiac output from theheart equals venous return to the heart.

Step of the circuicity:

1. Oxygenated blood fills the left ventricle. Blood that has been oxygenated in thelungs returns to the left atrium via the pulmonary vein. This blood then flows fromthe left atrium to the left ventricle through the mitral valve (the AV valve of the leftheart).

2. Blood is ejected from the left ventricle into the aorta. Blood leaves the left ventriclethrough the aortic valve (the semilunar valve of the left side of the heart), which islocated between the left ventricle and the aorta. When the left ventricle contracts,the pressure in the ventricle increases, causing the aortic valve to open and blood tobe ejected forcefully into the aorta. (As noted previously, the amount of bloodejected from the left ventricle per unit time is called the cardiac output.) Blood thenflows through the arterial system, driven by the pressure created by contraction ofthe left ventricle.

3. Cardiac output is distributed among various organs. The total cardiac output of theleft heart is distributed among the organ systems via sets of parallel arteries. Thus,simultaneously, 15% of the cardiac output is delivered to the brain via the cerebral

arteries, 5% is delivered to the heart via the coronary arteries, 25% is delivered tothe kidneys via the renal arteries, and so forth. Given this parallel arrangement ofthe organ systems, it follows that the total systemic blood flow must equal thecardiac output.The percentage distribution of cardiac output among the various organ systems isnot fixed, however. For example, during strenuous exercise, the percentage of thecardiac output going to skeletal muscle increases, compared with the percentage atrest. There are three major mechanisms for achieving such a change in blood flow toan organ system. In the firstmechanism, the cardiac output remains constant, butthe blood flow is redistributed among the organ systems by the selective alteration

of arteriolar resistance. In this scenario, blood flow to one organ can be increased atthe expense of blood flow to other organs. In the second mechanism, the cardiac


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output increases or decreases, but the percentage distribution of blood flow amongthe organ systems is kept constant. Finally, in a thirdmechanism, a combination ofthe first two mechanisms occurs in which both cardiac output and the percentagedistribution of blood flow are altered. This third mechanism is used, for example, inthe response to strenuous exercise: Blood flow to skeletal muscle increases to meet

the increased metabolic demand by a combination of increased cardiac output andincreased percentage distribution to skeletal muscle.

4. Blood flow from the organs is collected in the veins. The blood leaving the organs isvenous blood and contains waste products from metabolism, such as carbon dioxide(CO2). This mixed venous blood is collected in veins of increasing size and finally inthe largest vein, the vena cava. The vena cava carries blood to the right heart.

5. Venous return to the right atrium. Because the pressure in the vena cava is higherthan in the right atrium, the right atrium fills with blood, the venous return. In thesteady state, venous return to the right atrium equals cardiac output from the leftventricle.

6. Mixed venous blood fills the right ventricle. Mixed venous blood flows from theright atrium to the right ventricle through the AV valve in the right heart, thetricuspid valve.

7. Blood is ejected from the right ventricle into the pulmonary artery. When the rightventricle contracts, blood is ejected through the pulmonic valve (the semilunar valveof the right side of the heart) into the pulmonary artery, which carries blood to thelungs. Note that the cardiac output ejected from the right ventricle is identical to thecardiac output that was ejected from the left ventricle. In the capillary beds of thelungs, oxygen (O2) is added to the blood from alveolar gas, and CO 2 is removed fromthe blood and added to the alveolar gas. Thus, the blood leaving the lungs has more

O2 and less CO2 than the blood that entered the lungs.8. Blood flow from the lungs is returned to the heart via the pulmonary vein.

Oxygenated blood is returned to the left atrium via the pulmonary vein to begin anew cycle.

FETAL CIRCULATION


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NEONATAL CIRCULATION


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It is essential to understand basic cardiovascular physiology to appreciate thepathophysiology of congenital and acquired heart problems. The primary function ofthe cardiovascular system is to pump blood. Cardiac output (liters per minute) is thebasic measure of how much blood the heart pumps.

Cardiac Output and Its Determinants

The determinants of cardiac output (CO) are heart rate (HR) and stroke volume (SV).

CO = HR SV

This relationship can be simplified using the determinants of SV end-diastolic volume(EDV) and ejection fraction (EF).

CO = HR EDV EF

Therefore, the only way cardiac output can increase or decrease is if heart rate, end-diastolic volume, and/or ejection fraction increase(s) or decrease(s). There are manyfactors that affect heart rate, end-diastolic volume, and ejection fraction. Hence,these factors change cardiac output. Heart rate may be affected by a variety of drugs

and inherent conduction abnormalities. Factors that limit the increase in heart rate,such as -blockers, atrioventricular block, and sick sinus syndrome, negatively affect


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the increase in cardiac output. End-diastolic volume (preload) increases with anincrease in intravascular volume and vice versa. Also, conditions such as restrictivecardiomyopathy, pericardial effusion, and constrictive pericarditis that limitventricular filling decrease diastolic volume and hence cardiac output.

Ejection fraction decreases with decreased preload, increased afterload, anddecreased contractility. Ejection fraction increases with increased preload,decreased afterload, increased contractility, and increased heart rate. Contractility,by affecting ejection fraction, changes cardiac output. Contractility is easy toconceptualize but difficult to measure. Simplistically, ejection fraction would seem tobe an excellent measure of contractility. However, because ejection fraction isaffected by afterload, preload, heart rate, and contractility, it is not a pure measureof contractility. Contractility can change in response to either positive or negativeinotropic agents. As is apparent from this discussion, truly understanding a basicrelationship such as

CO = HR EF EDV

allows one to truly understand cardiovascular physiology and how diseases anddifferent treatment strategies affect cardiac function.There are several other relationships with which one should be acquainted. Theseare described in the following sections.

Ohm's Law

Resistance (R) = Pressure (P)/ Flow (Q)

Ohm's law describes the relationship between pressure, flow, and resistance.Understanding this relationship is essential to understand, for example, thedifference between pulmonary hypertension and pulmonary vascular obstructivedisease, the effect of left-to-right shunts on pulmonary artery pressure, and theeffects of pulmonary artery and systemic vascular resistances on the volume of left-to-right and right-to-left shunts.It is obvious from this relationship that increased pulmonary artery pressure couldresult from increased resistance in the pulmonary bed or increased flow into the

pulmonary bed or both.

P = R Q

It also is clear from this relationship that flow decreases as resistance increases.Q = P/RThis explains why a drug that decreases systemic vascular resistance (afterloadreduction) increases cardiac output (Q).

Flow is directly related to the driving pressure and the radius of the tube andindirectly to the viscosity of the fluid and the length of the tube through which flow

occurs. If one solves the equation for P/Q (which is resistance), it becomes apparentthat resistance is related directly to viscosity and the length of the tube and inversely


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related to the radius of the tube. For example, as the viscosity of blood increases (aswith polycythemia), pulmonary artery resistance and pressure increase.

Fick PrincipleIn 1870, Fick conceived a method of determining cardiac output on the basis of

oxygen consumption and mixed venous and arterial oxygen content. The Fickprinciple is described by the following formula:

CO = [V with dot above]O2/[Hemoglobin] 1.36 (SaturationART -SaturationMV) 10

where[V with dot above]O2 = oxygen consumption,ART = arterialMV = mixed venous.

For oxygen to be consumed, it must be bound to the red blood cells enteringthe lungs and carried from the lungs to the tissues of the body. By knowing theamount of oxygen that is bound to the red blood cells entering the lungs, theamount that is bound to the red blood cells leaving the lungs, and the oxygenconsumption, one can determine the rate of blood flow through the lungs. This isbetter understood if one considers this process as being analogous to coal beingloaded onto a train The coal represents oxygen, the train represents the pulmonaryblood flow, and each car represents individual

D. PATHOPHYSIOLOGYCYANOSIS

Cyanosis refers to a bluish color of the skin and mucous membranes resulting

from an increased quantity of reduced hemoglobin, or of hemoglobin derivatives, in

the small blood vessels of those areas. It is usually most marked in the lips, nail beds,

ears, and malar eminences. Cyanosis, especially if developed recently, is more

commonly detected by a family member than the patient. The florid skin

characteristic of polycythemia vera must be distinguished from the true cyanosis

discussed here. A cherry-colored flush, rather than cyanosis, is caused by COHb . Thedegree of cyanosis is modified by the color of the cutaneous pigment and the

thickness of the skin, as well as by the state of the cutaneous capillaries. The

accurate clinical detection of the presence and degree of cyanosis is difficult, as

proved by oximetric studies. In some instances, central cyanosis can be detected

reliably when the SaO has fallen to 85%; in 2 others, particularly in dark-skinned

persons, it may not be detected until it has declined to 75%. In the latter case,

examination of the mucous membranes in the oral cavity and the conjunctivae

rather than examination of the skin is more helpful in the detection of cyanosis. The

increase in the quantity of reduced hemoglobin in the mucocutaneous vessels thatproduces cyanosis may be brought about either by an increase in the quantity of


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venous blood as the result of dilatation of the venules and venous ends of the

capillaries or by a reduction in the SaO in the capillary blood. In general, cyanosis

becomes apparent 2 when the mean capillary concentration of reduced hemoglobin

exceeds 40 g/L (4 g/dL). It is the absolute rather than the relative quantity of reduced

hemoglobin that is important in producing cyanosis.Cyanosis may be subdivided into central and peripheral types. In the central

type, the SaO is reduced or an abnormal hemoglobin de- 2 rivative is present, and

the mucous membranes and skin are both affected. Peripheralcyanosis is due to a

slowing of blood flow and abnormally great extraction of O2 from normally

saturated arterial blood. It results from vasoconstriction and diminished peripheral

blood flow, such as occurs in cold exposure, shock, congestive failure, and peripheral

vascular disease. Often in these conditions the mucous membranes of the oral cavity

or those beneath the tongue may be spared. Clinical differentiation between central

and peripheral cyanosis may not always be simple, and in conditions such ascardiogenic shock with pulmonary edema there may be a mixture of both types.

TABLE 31-1 Causes of Cyanosis

CENTRAL CYANOSIS

Decreased arterial oxygen saturation

Decreased atmospheric pressurehigh altitudeImpaired pulmonary function

Alveolar hypoventilation

Uneven relationships between pulmonary ventilation and perfusion

(perfusion of hypoventilated alveoli)Impaired oxygen diffusion

Anatomic shunts

Certain types of congenital heart diseasePulmonary arteriovenous fistulas

Multiple small intrapulmonary shuntsHemoglobin with low affinity for oxygen

Hemoglobin abnormalitiesMethemoglobinemiahereditary, acquired

Sulfhemoglobinemaacquired

Carboxyhemoglobinemia (not true cyanosis)PERIPHERAL CYANOSIS

Reduced cardiac output

Cold exposure

Redistribution of blood flow from extremitiesArterial obstruction

Venous obstructionCENTRAL CYANOSIS Decreased SaO results from a marked 2 reduction in the

PaO . This reduction may be brought about by a decline 2 in the FIO withoutsufficient compensatory alveolar hyperventilation 2 to maintain alveolar PO .Cyanosis does not occur to a significant de- 2 gree in an ascent to an altitude of 2500


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m (8000 ft) but is marked in a further ascent to 5000 m (16,000 ft). The reason forthis difference becomes clear on studying the S shape of the Hb-O2 dissociationcurve. At 2500 m (8000 ft) the FIO is about 120 mmHg, the 2 alveolar PO isapproximately 80 mmHg, and the SaO is nearly normal. 2 2 However, at 5000 m(16,000 ft) the FIO and alveolar PO are about 85 2 2 and 50 mmHg, respectively, and

the SaO is only about 75%. This 2 leaves 25% of the hemoglobin in the arterial bloodin the reduced form, an amount likely to be associated with cyanosis in the absenceof anemia. Similarly, a mutant hemoglobin with a low affinity for O2 (e.g., Hb Kansas)causes lowered SaO saturation and resultant central 2 Cyanosis. Seriously impaired

pulmonary function, through perfusion of unventilated or poorly ventilated areas ofthe lung or alveolar hypoventilation, is a common cause of central cyanosis. Thiscondition may occur acutely, as in extensive pneumonia or pulmonary edema, orchronically with chronic pulmonary diseases (e.g., emphysema). In the lattesituation, secondary polycythemia is generally present and clubbing of the fingersmay occur. However, in many types of chronic pulmonary disease with fibrosis and

obliteration of the capillary vascular bed, cyanosis does not occur because there isrelatively little perfusion of underventilated areas. Another cause of reduced SaO isshunting of systemic venous blood 2 into the arterial circuit. Certain forms ofcongenital heart disease are associated with cyanosis (Chap. 218). Since blood flowsfrom a higherpressure to a lower-pressure region, for a cardiac defect to result in aright-to-left shunt, it must ordinarily be combined with an obstructive lesion distal(downstream) to the defect or with elevated pulmonary vascular resistance. Themost common congenital cardiac lesion associated with cyanosis in the adult is thecombination of ventricular septal defect and pulmonary outflow tract obstruction(tetralogy of Fallot). The more severe the obstruction, the greater the degree of

right-to-left shunting and resultant cyanosis. In patients with patent ductusarteriosus, pulmonary hypertension, and right-to-left shunt, differential cyanosisresults; that is, cyanosis occurs in the lower but not in the upper extremities._The mechanisms for the elevated pulmonary vascular resistance that may

produce cyanosis in the presence of intra- and extracardiac communicationswithout pulmonic stenosis (Eisenmenger syndrome). Pulmonary arteriovenous

fistulae may be congenital or acquired, solitary or multiple, microscopic or massive.The severity of cyanosis produced by these fistulae depends on their size andnumber. They occur with some frequency in hereditary hemorrhagic telangiectasia.SaO reduction and cyanosis may also occur in some patients 2 with cirrhosis,

presumably as a consequence of pulmonary arteriovenous fistulas or portal veinpulmonary vein anastomoses.In patients with cardiac or pulmonary right-to-leftshunts, the presence and severity of cyanosis depend on the size of the shuntrelative to the systemic flow as well as on the Hb-O2 saturation of the venous blood.With increased extraction of O2 from the blood by the exercisingmuscles, the venousblood returning to the right side of the heart is more unsaturated than at rest, andshunting of this blood intensifies the cyanosis. Also, since the systemic vascularresistance falls with exercise, the right-to-left shunt is augmented by exercise inpatients with congenital heart disease and communications between the two sidesof the heart. Secondary polycythemia occurs frequently in patients with arterial O2

unsaturation and contributes to the cyanosis. Cyanosis can be caused by smallamounts of circulating methemoglobin and by even smaller amounts of


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sulfhemoglobin. Although they are uncommon causes of cyanosis, these abnormalhemoglobin pigments should be sought by spectroscopy when cyanosis is not readilyexplained by malfunction of the circulatory or respiratory systems. Generally, digitalclubbing does not occur with them. The diagnosis of methemoglobinemia can besuspected if the patients blood remains brown after being mixed in a test tube and

exposed to air.PERIPHERAL CYANOSIS Probably the most common cause of peripheral

cyanosis is the normal vasoconstriction resulting from exposure to cold air or water.When cardiac output is reduced, cutaneous vasoconstriction occurs as acompensatory mechanism so that blood is diverted from the skin to more vital areassuch as the central nervous system and heart, and cyanosis of the extremities mayresult, even though the arterial blood is normally saturated. Arterial obstruction toan extremity, as with an embolus, or arteriolar constriction, as in cold-inducedvasospasm, generally results in pallor and coldness, but there may be associatedcyanosis. Venous obstruction, as in thrombophlebitis, dilates the subpapillary venous

plexuses and thereby intensifies cyanosis.

MIDSYSTOLIC MURMURS

These also called systolic ejection murmurs, which are often crescendo-

decrescendo in shape, and occur when blood is ejected across the aortic or pulmonic

outflow tracts). The murmur starts shortly after S1, when the ventricular pressure

becomes high enough to open the semilunar valve. As the velocity of ejection

increases, the murmur gets louder; as ejection declines, it diminishes. The murmur

ends before the ventricular pressure falls enough to permit closure of the aortic orpulmonic leaflets. When the semilunar valves are normal, an increased flow rate (as

occurs in states of elevated cardiac output), ejection into a dilated vessel beyond the

valve, or increased transmission of sound through a thin chest wall may be

responsible for this murmur. Most benign, functional murmurs are midsystolic and

originate from the pulmonary outflow tract. Valvular or subvalvular obstruction of

either ventricle may also cause such a midsystolic murmur, the intensity being

related to the flow rate. The murmur of aortic stenosis is the prototype of the left-

sided midsystolic murmur. The location and radiation of this murmur are influenced

by the direction of the high-velocity jet within the aortic root. In valvular aortic

stenosis, the murmur is usually maximal in the second right intercostal space, with

radiation into the neck. In supravalvular aortic stenosis, the murmur is occasionally

loudest even higher, with disproportionate radiation into the right carotid artery. In

hypertrophic cardiomyopathy, the midsystolic murmur originates in the left

ventricular cavity and is usually maximal at the lower left sternal edge and apex, with

relatively little radiation to the carotids. When the aortic valve is immobile

(calcified), the aortic closure sound (A2)may be soft and inaudible so that the length

and configuration of the murmur are difficult to determine. Midsystolic murmurs

also occur in patients with mitral regurgitation or, less frequently, tricuspid


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regurgitation resulting from papillary muscle dysfunction. Such murmurs due to

mitral regurgitation are often confused with those originating in the aorta,

particularly in elderly patients.

CLUBBING FINGERS

The selective bullous enlargement of the distal segments of the finger and

toes due to proliferation of connective tissue, particularly on the dorsal surface, istermed clubbing; there is increased sponginess of the soft tissue at the base of the

nail. Clubbing may be hereditary, idiopathic or acquired and associated with a variety

of disorders, includin cyanotic congenital heart disease, infective endocarditis, and a

variet of pulmonary conditions (among them primary and metastatic lun cancer,

bronchiectasis, lung abscess, cystic fibrosis, and mesothelioma) as well as with some

gastrointestinal diseases (including inflammatory bowel disease and hepatic

cirrhosis). Although the mechanism of clubbing is unclear, it appears to be secondar

to a humoral substance that causes dilation of the vessels of the fingertip

Central cyanosis occurs because of right-to-left shunting of blood or because ofcomplete mixing of systemic and pulmonary blood flow. In the latter case, e.g.Fallot's tetralogy, the abnormality is described as cyanotic congenital heart disease.

Pulmonary hypertension results from large left-to-right shunts. The persistentlyraised pulmonary flow leads to the development of increased pulmonary arteryvascular resistance and consequent pulmonary hypertension. This is known as theEisenmenger reaction (or the Eisenmenger complex when due specifically to aventricular septal defect). The development of pulmonary hypertension significantlyworsens the prognosis.

Clubbing of the fingers occurs in congenital cardiac conditions associated withprolonged cyanosis.


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Paradoxical embolism of thrombus from the systemic veins to the systemic arterialsystem may occur when a communication exists between the right and left heart.There is therefore an increased risk of cerebrovascular accidents and also abscesses(as with endocarditis).

Polycythaemia can develop secondary to chronic hypoxaemia, leading to ahyperviscosity syndrome and an increased thrombotic risk, e.g. strokes.

Growth retardation is common in children with cyanotic heart disease. Syncope is common when severe right or left ventricular outflow tract obstruction is

present. Exertional syncope, associated with deepening central cyanosis, may occurin Fallot's tetralogy. Exercise increases resistance to pulmonary blood flow butreduces systemic vascular resistance. Thus, the right-to-left shunt increases andcerebral oxygenation falls.

Squatting is the posture adopted by children with Fallot's tetralogy. It results inobstruction of venous return of desaturated blood and an increase in the peripheralsystemic vascular resistance. This leads to a reduced right-to-left shunt and

improved cerebral oxygenation

E. DDTETRALOGY OF FALLOT

1. ABSTRACTTetralogy of Fallot is a congenital cardiac malformation that consists of an interventricular

communication, also known as a ventricular septal defect, obstruction of the right ventricular

outflow tract, override of the ventricular septum by the aortic root, and right ventricularhypertrophy. This combination of lesions occurs in 3 of every 10,000 live births, and accounts for 7

10% of all congenital cardiac malformations.

Patients nowadays usually present as neonates, with cyanosis of varying intensity based on

the degree of obstruction to flow of blood to the lungs. The aetiology is multifactorial, but reported

associations include untreated maternal diabetes, phenylketonuria, and intake of retinoic acid.

Associated chromosomal anomalies can include trisomies 21, 18, and 13, but recent experience

points to the much more frequent association of microdeletions of chromosome 22. The risk of

recurrence in families is 3%.

Useful diagnostic tests are the chest radiograph, electrocardiogram, and echocardiogram.

The echocardiogram establishes the definitive diagnosis, and usually provides sufficient information

for planning of treatment, which is surgical. Approximately half of patients are now diagnosed

antenatally.

Differential diagnosis includes primary pulmonary causes of cyanosis, along with other

cyanotic heart lesions, such as critical pulmonary stenosis and transposed arterial trunks. Neonates

who present with ductal-dependent flow to the lungs will receive prostaglandins to maintain ductal

patency until surgical intervention is performed. Initial intervention may be palliative, such as

surgical creation of a systemic-to-pulmonary arterial shunt, but the trend in centres of excellence is

increasingly towards neonatal complete repair. Centres that undertake neonatal palliation will


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perform the complete repair at the age of 4 to 6 months. Follow-up in patients born 30 years ago

shows a rate of survival greater than 85%. Chronic issues that now face such adults include

pulmonary regurgitation, recurrence of pulmonary stenosis, and ventricular arrhythmias. As the

strategies for surgical and medical management have progressed, the morbidity and mortality of

those born with tetralogy of Fallot in the current era is expected to be significantly improved.

2. ETIOLOGY AND EPIDEMIOLOGYThe etiology is multifactorial. Associated chromosomal anomalies can include trisomies 21, 18,

and 13, but recent experience points to the much more frequent association of microdeletions of

chromosome 22. As many as one-eighth of patients will have chromosomal abnormalities, such as

trisomy 21, 18, or 13. Up to one-fifth of patients with tetralogy and pulmonary stenosis, and two-

fifths of those with tetralogy and pulmonary atresia, will have microdeletions of chromosome

22q11.2. The deletion, manifested by varying degrees of palatal abnormalities, dysmorphic facies,

learning disabilities, immune deficiencies, and hypocalcaemia, is frequently referred to as the

DiGeorge Syndrome. There is a high incidence of chromosomal disorders in children with tetralogy ofFallot, such as Down syndrome and DiGeorge syndrome (a condition that causes heart defects, low

calcium levels, and immune deficiency).

Tetralogy of Fallot occurs in 3 of every 10,000 live births. It is the commonest cause of cyanotic

cardiac disease in patients beyond the neonatal age, and accounts for up to one-tenth of all

congenital cardiac lesions. Tetralogy of Fallot represents approximately 10% of cases of congenital

heart disease and is the most common cause of cyanotic congenital heart disease.

The risk of recurrence in a family is approximately 3%. Associations with maternal intake of

retinoic acid during the first trimester, poorly controlled diabetes, and untreated phenylketonuriahave also been described.

a. Risk FactorsFactors that increase the risk for this condition during pregnancy include:

Alcoholism in the mother

Diabetes

Mother who is over 40 years old

Poor nutrition during pregnancy

Rubella or other viral illnesses during pregnancy

b. Mortality/MorbidityNatural history varies and is mainly determined by the degree of RVOT(right ventricularoutflow tract) obstruction. Approximately 25% of untreated patients with tetralogy of Fallotand RVOT obstruction die within the first year of life, 40% die by 4 years, 70% die by 10years, and 95% die by 40 years. However, cases of survival of patients into their 80s havebeen reported. Due to advanced surgical techniques, a 40% reduction in deaths associatedwith tetralogy of Fallot was noted from 1979 to 2005

c. SexIncidence of tetralogy of Fallot is slightly higher in males than in females.

d. AgeTetralogy of Fallot occurs in newborns.


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3. ANATOMYThe embryological basis of the combination of lesions is antero-cephalad deviation of the

developing outlet ventricular septum, or its fibrous remnant should this septum fail to muscularise.

Such deviation, however, can be found in the absence of subpulmonary obstruction, as in the so-

called Eisenmenger ventricular septal defect . So as to produce the features of tetralogy of Fallot,therefore, it is also necessary to have abnormal morphology of the septoparietal trabeculations that

encircle the subpulmonary outflow tract . The combination of the deviated outlet septum and the

hypertrophied septoparietal trabeculations produce the characteristic right ventricular outflow tract

obstruction of tetralogy of Fallot (Figure below). The deviation of the muscular outlet septum is also

responsible for creating the malalignment type ventricular septal defect, and results in the aortic

override. The associated hypertrophy of the right ventricular myocardium is the haemodynamic

consequence of the anatomical lesions created by the deviated outlet septum.

a. The ventricular septal defectThe interventricular communication found in tetralogy of Fallot exists because of the

anterior and cephalad malalignment of the outlet portion of the muscular ventricular

septum, or of its fibrous remnant should the outflow cushions fail to muscularise during

embryonic development. The resulting hole is one of a number of those appropriately

described as a malalignment defect. In four-fifths of Caucasians with such a defect, the

postero-inferior margin of the hole between the ventricles is formed by an area of fibrous

continuity between the leaflets of the aortic and tricuspid valves, also involving the remnantof the interventricular portion of the membranous septum . In these patients, therefore, the

defect is also appropriately classified as being perimembranous. In the remaining one-fifth

of Caucasian patients, the postero-inferior rim of the defect is muscular. The muscular bar is

formed by continuity of the postero-inferior limb of the septomarginal trabeculation with

the ventriculo-infundibular fold. The muscular structure thus formed protects the ventricular

conduction axis during surgical closure of the defect. In a small proportion of Caucasian

patients, but in larger numbers of patients seen in the Far East, and in Central and South

America, the antero-superior margin of the ventricular septal defect is not formed by the

muscular outlet septum, but is formed by fibrous continuity between the leaflets of the

aortic and pulmonary valves. This morphology is the consequence of failure ofmuscularisation of the developing outlet septum. These patients, nonetheless, do have


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obstruction of the right ventricular outflow tract due to the malalignment of the fibrous

remnant of the outlet septum. The size of the ventricular septal defect can vary, but in

almost all instances, the interventricular communication is unrestrictive, allowing for

bidirectional shunting.

b. Override of the aortaBecause of the displacement of the malaligned outlet septum into the right ventricle, the

aortic root, of necessity, overrides the muscular ventricular septum. In the setting of

significant subpulmonary obstruction, shunting across the interventricular communication is

predominantly from right-to-left, which promotes ejection of deoxygenated blood into the

systemic circulation. The chronic volume load sustained by the overriding aorta is implicated

in the dilation of the aortic root noted in adults with tetralogy of Fallot.

c. Sub-pulmonary obstructionThe antero-cephalad deviation of the outlet septum, coupled with an anomalous

relationship to the septoparietal trabeculations, results in a narrowing of the subpulmonary

outflow tract. The obstructive muscular subpulmonary area thus created is a dynamic entity.The degree of stenosis created can be exacerbated by catecholamines, or a state of low

intravascular volume, predisposing the patients to sudden and acute episodes of

desaturation known as hypercyanotic spells. The obstruction to flow into the lungs often

extends beyond the subpulmonary outflow tract itself. The pulmonary valve may be

hypoplastic, with abnormally functioning leaflets, often having a bifoliate configuration. Not

infrequently, the pulmonary trunk, and the right and left pulmonary arteries, are diminutive,

exhibiting additional focal areas of narrowing.

4. ANATOMICAL VARIANTS OF TETRALOGY OF FALLOT, AND ASSOCIATED ANOMALIESa. Tetralogy of Fallot with pulmonary atresia

This lesion is at the most severe end of the spectrum of antero-cephalad deviation of the

outlet septum. Occasionally, however, the pulmonary valve is affected in isolation, being

imperforate rather than stenotic. In approximately half of patients with pulmonary atresia,

the right and left pulmonary arteries are confluent, with blood to the pulmonary arteries

flowing through the persistently patent arterial duct. In the other half, the pulmonary

arterial supply is multifocal. In these patients, if the pulmonary arteries are confluent or

continuous, the blood supply will likely originate only from multiple aorto-pulmonary

collateral arteries. If the pulmonary arteries are discontinous or absent, the blood supply to

the lungs will originate from multiple collateral arteries, or from a combination of collateral

arteries and an arterial duct. It is a general rule that a pulmonary segment will not be

supplied by both an arterial duct and a collateral artery. In cases of complex supply of blood

to the lungs, it is necessary to determine the proportion of pulmonary parenchyma supplied

by the intrapericardial pulmonary arteries as opposed to those parts supplied exclusively by

the collateral arteries. Although the collateral arteries do not depend on prostaglandin for

patency, they have the potential to stenose over time. In other instances, large collateral

arteries can provide unrestricted flow to the lungs, thus producing hypertensive pulmonary

vasculature. The long-term management of the pulmonary supply in patients with tetralogy

of Fallot and pulmonary atresia, therefore, is complicated.


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b. Tetralogy of Fallot with absent pulmonary valveMalalignment of the outlet septum with rudimentary formation of the leaflets of the

pulmonary valve, so-called absent pulmonary valve syndrome, is seen in around one-

twentieth of those alleged to have tetralogy of Fallot. The presence of rudimentary valvar

leaflets arrayed in circular fashion at the ventriculo-pulmonary junction results in free

pulmonary regurgitation throughout foetal life. The end result is that the chronic volume

load of the right ventricle is transmitted to the pulmonary arteries, with concomitant

dilation of these vessels. In severe cases, patients present with inspiratory and expiratory

stridor due to compression of the airways by the dilated pulmonary arteries. Although

compression and obstruction of the airways are partly responsible for cyanosis, there is also

focal narrowing at the ventriculo-pulmonary junction, contributing to the hypoxaemia in

these patients. In most instances, but certainly not all, the arterial duct is also absent.

c. Tetralogy of Fallot with double outlet right ventricleWith pronounced aortic override, the aorta becomes more committed to the right ventricle

than to the left ventricle, resulting in many instances in the ventriculo-arterial connection ofdouble outlet right ventricle. Although the physiology on presentation may not be altered,

there are important implications for surgical repair. Patients with the aorta originating

predominantly from the right ventricle are at greater risk of developing obstruction to the

newly created left ventricular outflow tract, the latter produced by the patch which closes

the ventricular septal defect while tunneling the left ventricle to the aorta. This patch, of

necessity, is appreciably longer than when the aorta arises mostly from the left ventricle.

d. Tetralogy of Fallot with atrioventricular septal defectAn atrioventricular septal defect combined with a common atrioventricular junction is found

in 2% of patients with tetralogy of Fallot. The presentation and initial medical management

remain unchanged, but surgical repair and post-operative care are more complex.e. Associated anomalies

Anomalous origins of the coronary arteries occur in up to one-sixth of patients, and should

be documented prior to surgical repair. The most common and relevant anomaly is origin of

the left anterior descending artery from the right coronary artery, with the anomalous artery

then coursing anterior to the subpulmonary outflow tract, a potential site of surgical

incision. Other associated lesions include atrial septal defects, and additional ventricular

septal defects, the latter usually being muscular. Straddling and overriding of the tricuspid

valve may also occur, which will complicate the closure of the ventricular septal defect. An

important finding when there is overriding of the orifice of the tricuspid valve is the

anomalous location of the atrioventricular conduction tissues. A right aortic arch, which is of

no haemodynamic consequence, is present in one-quarter of patients with tetralogy of

Fallot.

5. PATHOPHYSIOLOGYThe VSD is typically large; thus, systolic pressures in the right and left ventricles (and in the

aorta) are the same. Pathophysiology depends on the degree of right ventricular outflow

obstruction. A mild obstruction may result in a left-to-right shunt through the VSD; a severe


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obstruction causes a right-to-left shunt, resulting in low systemic arterial saturation (cyanosis) that is

unresponsive to supplemental O2.

In some children with tetralogy of Fallot, most often those several months up to 2 yr of age,

sudden episodes of profound cyanosis and hypoxia (tet spell) may occur, which may be lethal. A spell

may be triggered by any event that slightly decreases O2 saturation (eg, crying, defecating) or thatsuddenly decreases systemic vascular resistance (eg, playing, kicking legs when awakening) or by

sudden onset of tachycardia or hypovolemia. The mechanism of a tet spell remains uncertain, but

several factors are probably important in causing an increase in right to left shunting and a fall in

arterial saturation. Factors include an increase in right ventricular outflow tract obstruction and a

decrease in systemic resistancea vicious circle caused by the initial fall in arterial Po2, which

stimulates the respiratory center and causes hyperpnea and increased adrenergic tone. The

increased circulating catecholamines then stimulate increased contractility, which increases outflow

tract obstruction.

6. CLINICAL MANIFESTATIONS AND DIAGNOSTIC WORK-UPMost babies with tetralogy of Fallot are "blue" which means that they have lower blood oxygen

levels than normal. The medical term for low blood oxygen levels is cyanosis. The blue color is best

seen in the lips and under the fingernail beds but can be quite hard to detect just by looking at the

baby. Most babies are otherwise healthy and grow normally although some have other health

problems.

The initial presentation of tetralogy of Fallot varies depending on the severity of the obstruction

of blood flow to the lungs. Most patients will present in the neonatal period with mild-to-moderate

cyanosis, but typically without respiratory distress. Neonates with severe right ventricular outflowobstruction (or atresia) have severe cyanosis and dyspnea with feeding with poor weight gain. But

those with mild obstruction may not have cyanosis at rest.More uncommonly, patients with very

mild right ventricular outflow tract obstruction at birth may be diagnosed at a couple months of age

as the obstruction worsens resulting in newly noticed cyanosis and a louder murmur. Because

patients with tetralogy of Fallot have obstruction to pulmonary blood flow, they will not present

with signs of heart failure such as failure to thrive. Irritability and lethargy are rarely seen in patients

with tetralogy of Fallot except in the setting of a hypercyanotic spell. Clubbing is also highly unusual

in the modern era since newly diagnosed patients undergo surgical repair before clubbing has time

to develop.

Tet spells may be precipitated by activity and are characterized by paroxysms of hyperpnea

(rapid and deep respirations), irritability and prolonged crying, increasing cyanosis, and decreasing

intensity of the heart murmur. The spells occur most often in young infants; peak incidence is age 2

to 4 mo. A severe spell may lead to limpness, seizures, and occasionally death. During play, some

toddlers may intermittently squat, a position that increases systemic vascular resistance and aortic

pressure, which decreases right to left ventricular shunting and thus raises arterial O2 saturation.

Auscultation detects a harsh grade 3 to 5/6 systolic ejection murmur at the left mid and upper

sternal border. The murmur in tetralogy is always due to the pulmonary stenosis; the VSD is silent

because it is large and has no pressure gradient. The 2nd heart sound is often single because the


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pulmonary component is markedly reduced. A prominent right ventricular impulse and a systolic

thrill may be present.

The second heart sound in patients with tetralogy of Fallot may be single and loud, and a harsh

systolic ejection murmur will be present, emanating from the obstructed subpulmonary outflow

tract. Flow across the interventricular communication in tetralogy of Fallot is usually not turbulent,and therefore not audible. Patients with severe obstruction, and very little antegrade flow across the

subpulmonary outflow tract, will be more significantly cyanotic and have a less prominent murmur.

Once the lesion is suspected, an electrocardiogram and chest radiograph should be performed.

The electrocardiogram will demonstrate right axis deviation and prominent right ventricular forces,

with large R waves in the anterior precordial leads and large S waves in the lateral precordial leads.

Although the electrocardiogram is similar to that of a normal newborn, the right ventricular

hypertrophy and right axis deviation will not normalize in a patient with tetralogy of Fallot. The

classical chest radiograph will demonstrate a boot-shaped cardiac silhouette. This is due to upward

displacement of the right ventricular apex as a consequence of the right ventricular hypertrophy,and a narrowing of the mediastinal shadow due to the hypoplastic pulmonary outflow tract.

Diagnosis is confirmed with echocardiography. The severity of the subpulmonary obstruction, its

dynamic component, the size of the right and left pulmonary arteries, and any additional sources of

flow of blood to the lungs will all be delineated. The degree of aortic override, the size of the

interventricular communication, as well as the presence of other associated lesions, will be

identified. Cardiac catheterisation is now rarely needed due to the high sensitivity and specificity of

echocardiographic images.

a. Hypercyanotic spellsThe hypercyanotic spell is characterised by a sudden and striking decrease in the saturationof oxygen due to acute and complete, or near complete, obstruction of the subpulmonary

outflow tract. Not all patients with tetralogy of Fallot will have hypercyanotic spells. The

spells typically begin to occur at approximately a couple months of age at times of agitation

or decreased hydration, both of which exacerbate the dynamic infundibular obstruction. The

murmur produced by the muscular obstruction is absent during a true spell, due to nearly

absent antegrade flow across the right ventricular outflow tract. Patients become severely

cyanotic, hyperpnoeic, and lethargic. With the development of metabolic acidosis, there is

an increase in pulmonary vascular resistance, with a decrease in systemic vascular

resistance. Cardiac output becomes compromised due to myocardial ischaemia. Impendingcollapse and death can ensue.

b. Imaging RadiographyOn radiographs, the cardiac silhouette in patients with tetralogy of Fallot is normal in size;

however, right ventricular hypertrophy can elevate the left ventricle. Combined with a small

or absent main pulmonary artery segment, the heart can have the classic boot-shaped

appearance (as seen in the image below). Most children with tetralogy of Fallot do not have

boot-shaped heart.


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Radiograph of a boot-shaped heart in an infant with tetralogy of Fallot.

Typically, the appearance of the vascularity of the pulmonary artery is reduced, but it can

also be normal. Decreased pulmonary vascularity is frequently difficult for the general

radiologist to appreciate. Large collaterals may give the appearance of normal vascularity.

The enlarged aorta in children with a right-sided arch can cause airway compression that can

be identified on chest radiographs, as demonstrated in the images below. A right-sided arch

is present in 25% of children with tetralogy of Fallot, and it can be identified by means ofdirect visualization, with displacement of the trachea to the left or with increased opacity of

the spinal pedicles on the ipsilateral side of the aortic arch. The position of the aortic arch

influences surgical planning because Blalock-Taussig shunts are more easily placed on the

contralateral side of the aortic arch. Modified Blalock-Taussig shunts can be placed

bilaterally.

Degree of confidence.

Confidence in conventional chest radiographic findings increases with the

radiologist's reading experience. The use of echocardiography has reduced theimportance of chest radiography in the initial diagnosis of congenital heart disease.

Echocardiography should be used to confirm radiographic findings that are

suggestive of tetralogy of Fallot.

False positives/negatives

The boot-shaped heart is overlabeled in neonates, who normally have right

ventricular hypertrophy. If the chest radiograph shows lordosis, a normal heart may

appear boot shaped. A right-sided aortic arch in a child with congenital heart disease

is most commonly associated with tetralogy of Fallot. Children with a large right-

sided aortic arch may have a double aortic arch or an aberrant left subclavian artery

without congenital heart disease. Other forms of cyanotic heart disease that are


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associated with a right-sided aortic arch are usually hypervascular and associated

with cardiomegaly (eg, truncus arteriosus, transposition of the great arteries).

Although cyanosis and a right-sided aortic arch are associated with tetralogy of

Fallot, the presence of cardiomegaly and increased pulmonary vascularity make an

admixture lesion the more likely diagnosis. Transposition of the great vessels or

truncus arteriosus is associated with increased pulmonary vascularity, cardiomegaly,

and cyanosis, as well as a right-sided arch. Approximately one third of children with

truncus arteriosus have a right-sided aortic arch. Only 5% of children with

transposition of the great vessels have a right-sided aortic arch, but this is a more

common form of congenital heart disease than truncus arteriosus.

Computed TomographyComputed tomography (CT) scanning has an infrequent role in the evaluation of tetralogy of

Fallot.4,5 This modality is useful for the evaluation of surgical complications such as infection

or pseudoaneurysm formation. Helical CT scanning can be used to identify airwaycompression that is caused by a large ascending aorta that is associated with tetralogy of

Fallot.

Magnetic Resonance ImagingSpin-echo MRI can be used to identify the morphologic abnormalities of tetralogy of Fallot,

which are as follows: right ventricular outflow tract obstruction, ventricular septal defect,

right ventricular hypertrophy, and an overriding aorta. (Examples of these features are seen

in the image below.)

Magnetic resonance image of the heart in an infant with tetralogy of Fallot. This image

shows a large ventricular septal defect and right ventricular hypertrophy. Note the

descending aorta is on the right, consistent with a right-sided aortic arch.

The confluence, presence, and size of the branch pulmonary arteries can be identified (see

the image below). MRI measurements of the size of the pulmonary and branch pulmonary

arteries are as accurate as angiographic measurements, and they can be used to calculate

the McGoon ratio and the Nakata index.


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Magnetic resonance image of tetralogy of Fallot in an infant. This image shows a large

ascending aorta and the presence of pulmonary atresia. The oval shape of the descending

aorta is secondary to large collateral vessels.

Postoperative evaluation of pulmonary artery stenoses is better with MRI than with

echocardiography. Cine imaging can be used to identify pulmonary stenosis or regurgitation,which is depicted as flow voids. Right ventricular enlargement is best quantified with MRI.

Flow-analysis quantification of pulmonary regurgitation is unique to MRI. Although gradients

can be measured with echocardiography, only MR flow analysis enables the accurate cross-

sectional measurement of flow.

Degree of confidence

Experienced operators are required for a high-quality MRI evaluation. If properly

performed, MRI can replace preoperative angiography, which is more invasive.

Oblique imaging with thin sections may be necessary to verify pulmonary arterial

confluence and identify hypoplastic pulmonary arteries in neonates and infants.

Flow analysis of pulmonary regurgitation is susceptible to aliasing if the velocity

encoding is too low.

UltrasonographyEchocardiography is the primary imaging method for examining a child in whom tetralogy of

Fallot is suspected. Intracardiac anomalies, including pulmonary infundibular and valvular

stenosis and the position of the aortic root overriding the ventricular septal defect, are

identified with 2-dimensional echocardiography. The origins of the coronary arteries can

also be identified. Doppler ultrasonographic examination of the pulmonary outflow tract can

be used to measure the velocity gradient in the right ventricular outflow tract and todifferentiate severe stenosis from atresia. Continuity of the branch pulmonary artery with

the main pulmonary artery can be identified, and the size of the branch pulmonary arteries

can be measured. The initial placement of palliative shunts is likely in children who have

small branch pulmonary arteries in order to allow the pulmonary arteries to grow before

corrective surgery. The full length of the shunts may not be visible; however, Doppler

ultrasonography can be used to verify shunt patency, even when the entire length of the

shunt cannot be imaged.


Intracardiac and central pulmonary artery abnormalities are identified in thepresurgical patient with a high degree of confidence. Ultrasonographic windows in


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the older child and young adult limit the usefulness of echocardiography in

postoperative follow-up imaging. Postoperative fibrosis in the mediastinum also

reduces the effectiveness of echocardiography. The pulmonary arteries and

systemic-pulmonary arterial shunts are difficult to evaluate after surgery in children.

Pulmonary regurgitation, a common complication of corrective surgery, is better

evaluated with MRI.

AngiographyAngiography is the traditional criterion standard and best modality for the evaluation of the

pulmonary and coronary arterial morphology, as well as the morphology of the systemic

collateral arteries.The branch pulmonary arteries have a characteristic seagull appearance

(as seen in the image below). Pulmonary arterial measurements for the calculation of the

McGoon ratio and Nakata index are critical to surgical planning. An aortic root injection is

used to evaluate the position and number of coronary arteries.

Angiogram in an infant with tetralogy of Fallot and a right-sided aortic arch. This image

shows the pulmonary artery is hypoplastic, and the branch pulmonary arteries have a

characteristic seagull appearance.


Catheter studies remain the criterion standard for blood pressure measurements

and morphologic imaging of the coronary and branch pulmonary arteries.

Noninvasive techniques are preferred when they are available so that vascular

access for potential future interventional procedures is preserved.

False positives/negativesUnlike inherently tomographic studies such as echocardiography, MRI, and CT

scanning, angiography may be limited by overlapping structures that may obscure

other structures, despite the use of multiple planes.

7. ANTENATAL DIAGNOSISTetralogy of Fallot can be diagnosed antenatally as early as 12 weeks of gestation. In a

population-based study, however, only half of the cases were detected during routine obstetric

ultrasonic screening. In general, patients who are referred for foetal echocardiography with a

suspicion of tetralogy of Fallot have the most severe phenotypes. Other reasons for referral forfoetal echocardiography include discovery of extra-cardiac malformations, or known chromosomal


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abnormalities. As a result, patients referred for foetal echocardiography tend to have worse

outcomes when compared to patients who are diagnosed postnatally. The foetus with tetralogy can

be delivered vaginally, but efforts should be made for delivery to occur in a centre where paediatric

cardiologists are available to aid in the postnatal care.

8. MANAGEMENTFor symptomatic neonates, prostaglandin E1 infusionFor tet spells, positioning, calming, O2, and sometimes drugsSurgical repairNeonates with severe cyanosis may be palliated with an infusion of prostaglandin E1 (0.05 to0.1 g/kg/min IV) to open the ductus arteriosus.Tet spells: Tet spells are treated by placing infants in a knee-chest position (older childrenusually squat spontaneously and do not develop tet spells), establishing a calm environment,and giving O2. If the spell persists, options (roughly in order of preference) include morphine0.1 to 0.2 mg/kg IV or IM, IV fluids for volume expansion, NaHCO3 1 mEq/kg IV, and propranolol

starting at 0.02 to 0.05 mg/kg, titrated up to 0.1 to 0.2 mg/kg IV if needed for effect. If thesemeasures do not control the spell, systemic BP can be increased with ketamine 0.5 to 3 mg/kgIV or 2 to 3 mg/kg IM ( ketamine also has a beneficial sedating effect) or phenylephrine startingat 5 g/kg and titrating up to 20 g/kg IV for effect. Ultimately, if the preceding steps do not

relieve the spell or if the infant is rapidly deteriorating, intubation with muscle paralysis andgeneral anesthesia may be necessary. Propranolol 0.25 to 1 mg/kg po q 6 h may preventrecurrences, but most experts feel that even one significant spell indicates the need forexpeditious surgical repair.Definitive management: Complete repair consists of patch closure of the VSD, widening of theright ventricular outflow tract with muscle resection and pulmonary valvuloplasty, and a limitedpatch across the pulmonic annulus or main pulmonary artery if necessary. Surgery is usually

done electively at age 3 to 6 mo but can be done at any time if symptoms are present.In neonates and very small infants with complex anatomy, initial palliation may be preferred tocomplete repair; the usual procedure is a modified Blalock-Taussig shunt, in which thesubclavian artery is connected to the ipsilateral pulmonary artery with a synthetic graft.Perioperative mortality rate for complete repair is < 5% for uncomplicated tetralogy of Fallot.For untreated patients, survival rates are 55% at 5 yr and 30% at 10 yr.Endocarditis prophylaxis is recommended preoperatively but is required only for the first 6 moafter repair unless there is a residual defect adjacent to a surgical patch or prosthetic material.

Clinical management is determined by the degree and type of subpulmonary obstruction, incombination with the preference of the centre for the timing of surgical intervention. Depending on

the severity of obstruction within the subpulmonary outflow tract, an infusion of prostaglandin maybe initiated to preserve ductal patency, and provide a stable source of flow of blood to the lungs.Patients who require such an infusion will most likely require surgical intervention prior to dischargefrom the hospital. For those patients who have adequate forward flow through the subpulmonaryoutflow tract after ductal closure, management consists of close follow-up until a complete repair isperformed.

Some centres will perform complete repairs in all neonates. Others will palliate symptomaticneonates, and perform a complete repair in all patients at the age of 4 to 6 months. Palliation, whichfrequently does not require cardiopulmonary bypass, establishes a secure source of flow of blood tothe lungs by placing a prosthetic tube between a systemic and a pulmonary artery. The most

common type of aorto-pulmonary shunt is known as the modified Blalock-Taussig shunt. Thisconsists of a communication between a subclavian and pulmonary artery on the same side. A


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complete repair, always performed under cardiopulmonary bypass, consists of closing theinterventricular communication with a patch channeling the left ventricle to the aortic root, relief ofthe subpulmonary obstruction, and reconstruction, if necessary, of the pulmonary arteries.

Complete neonatal repair provides prompt relief of the volume and pressure overload on the

right ventricle, minimises cyanosis, decreases parental anxiety, and eliminates the theoretical risk ofstenosis occurring in a pulmonary artery due to a palliative procedure. Patients who undergo a

successful complete repair during the neonatal period will be unlikely to require more than one

intervention in the first year of life, but are not free from reintervention. Concerns regarding such

neonatal complete repairs include exposure of the neonatal brain to cardiopulmonary bypass, and

the increased need to place a patch across the ventriculo-pulmonary junction when compared to

older age at repair. Patches placed across the ventriculo-pulmonary junction, so-called transannular

patches, create a state of chronic pulmonary regurgitation, which increases morbidity in young

adults, producing exercise intolerance and ventricular arrhythmias. If left untreated, this increases

the risk of sudden death. The effect of cardiopulmonary bypass on the neonatal brain, and the

associated risk of longer stay in hospital and the intensive care unit, is not trivial. Studies ofneurodevelopmental outcomes of neonates undergoing cardiopulmonary bypass compared to older

children have shown lower intelligence quotients in patients exposed to bypass as neonates. Longer

periods of bypass, and longer stays in the intensive care unit, have been associated with an

increased risk for neurological events and abnormal neurological findings on follow-up. While some

studies have not found cyanosis itself to be responsible for cognitive problems in children with

congenitally malformed hearts, others have implicated chronic cyanosis as a factor contributing to

impaired motor skills, decreased academic achievement, and worsened behavioural outcomes. In

the absence of randomised control trials, assessing the risk and benefits of the two surgical

strategies has been notoriously difficult.

In summary, patients with cyanotic tetralogy of Fallot will either undergo neonatal complete

repair or neonatal palliation with an aortopulmonary shunt followed by a complete repair at four to

six months of age. Peri-operative mortality rates for either surgical approach is less than 3% and

since neither strategy has shown superior results, surgical management remains dependent on the

protocols preferred by the individual centres.

a. Management of the anatomical variants of tetralogy of FallotNeonates born with tetralogy of Fallot with pulmonary atresia who do not have stable flow

to the lungs through collateral arteries will require surgical intervention prior to discharge

from the hospital. In newborns with tetralogy of Fallot with absent pulmonary valve, surgicalrepair may be required prior to initial discharge from hospital if obstruction to the airways is

a prominent symptom. In cases with tetralogy of Fallot with atrioventricular septal defect,

complete repair is usually performed later in life compared to patients with uncomplicated

tetralogy of Fallot, typically between the ages of 6 and 12 months. If significantly cyanotic at

birth, most centres still opt for initial palliation rather than complete repair in these patients.

Freedom from reoperation is decreased compared to patients with uncomplicated tetralogy

of Fallot.

b. Management of the hypercyanotic spellOvercoming a hypercyanotic spell requires maneuvers to re-establish adequate balance

between the systemic and pulmonary flows. Treatment must focus on decreasing


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pulmonary, and increasing systemic, vascular resistance, hence promoting left to right flow

across the ventricular septal defect and into the subpulmonary outlet. Parents at home with

a child suffering such spells are taught to place their child in the knee-to-chest position in an

effort to increase systemic vascular resistance and promote systemic venous return to the

right heart. This will theoretically increase intracardiac shunting from left-to-right across the

interventricular communication, as well as increase the preload of the right ventricle.

Emergency services should be contacted immediately. Medical management will consist of

establishing immediate intravenous access to allow prompt administration of fluids, which

will improve right ventricular preload. Oxygen should be initiated to decrease peripheral

pulmonary vasoconstriction, and improve oxygenation once flow of blood to the lungs is re-

established. Subcutaneous morphine should be administered to decrease the release of

catecholamines. This will increase the period of right ventricular filling by decreasing the

heart rate, and promote relaxation of the infundibular spasm. If the patient remains

hypercyanotic after these measures, he or she should be paralysed and intubated, with

phenylephrine administered intravenously to increase systemic vascular resistance. The longhalf-life, and potential side effects, such as hypotension and cardiac dysfunction, of beta

blockers precludes their routine use in the emergency situation. Propranolol has been used

in small doses in the chronic care of patients deemed to be at risk for spells in an effort to

minimise the infundibular spasm responsible for the episodes. Once a patient requires

prophylaxis by beta-blockade, surgical referral should occur to prevent the potential tragic

and unpredictable outcome of a hypercyanotic spell.

9. PROGNOSISStudies of immediate and long-term follow-up in tetralogy of Fallot reveal excellent outcomes.

Patients born 30 years ago with tetralogy of Fallot have an 85% long-term rate of survival, and in the

absence of serious residuae are able to lead normal lives as evidenced by the ability to carry

successful pregnancies for example. Chronic issues that face the current population of adults

subsequent to their surgical repair include the haemodynamic manifestations of chronic pulmonary

regurgitation, recurrent or residual pulmonary stenosis, and ventricular arrhythmias. The prognosis

of patients born in the current era is expected to be substantially improved due to advances in

surgical and medical management that have occurred over the past couple of decades. As for all

patients with congenitally malformed hearts, the management of the patient with tetralogy of Fallot

does not end at the time of complete repair. Follow-up by cardiologists trained in congenital cardiac

disease will remain a life-long experience.

10.POSSIBLE COMPLICATIONSDelayed growth and development

Irregular heart rhythms (arrhythmias)

Seizures during periods when there is not enough oxygen

Death


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TRANSPOSITION OF GREAT ARTERY

1. ABSTRACTTransposition of the great arteries (TGA) is a congenital (present at birth) heart defect that

occurs when the large vessels that take blood away from the heart to the lungs, or to the body, areimproperly connected. Normally:

oxygen-poor (blue) blood returns to the right atrium from the body, travels to the rightventricle, then is pumped through the pulmonary artery into the lungs where it receivesoxygen.Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the leftventricle, then is pumped through the aorta out to the body.

In transposition of the great arteries, the aorta is connected to the right ventricle, and thepulmonary artery is connected to the left ventricle-the exact opposite of a normal heart's anatomy:

Oxygen-poor (blue) blood returns to the right atrium from the body, passes through theright atrium and ventricle, then goes into the misconnected aorta back to the body.

Oxygen-rich (red) blood returns to the left atrium from the lungs, passes through the leftatrium and ventricle, then goes into the pulmonary artery and back to the lungs.

Two separate circuits are formed -- one that circulates oxygen-poor (blue) blood from thebody back to the body, and another that recirculates oxygen-rich (red) blood from the lungs back tothe lungs. Other heart defects are often associated with TGA, and actually may be necessary in orderfor an infant with transposition of the great arteries to live. Openings in the wall separating the leftand right sides of the heart, called atrial septal defect or ventricular septal defect, will allow bloodfrom one side to mix with blood from another, creating "purple" blood with an oxygen levelsomewhere between that of the oxygen-poor (blue) and the oxygen-rich (red) blood.

Babies with TGA have two separate circuits -- one that circulates oxygen-poor (blue) bloodfrom the body back to the body, and another that recirculates oxygen-rich (red) blood from thelungs back to the lungs. Without an additional heart defect that allows mixing of oxygen-poor (blue)and oxygen-rich (red) blood, such as an atrial or ventricular septal defect, infants with TGA will haveoxygen-poor (blue) blood circulating through the body, a situation that is critical. Even with anadditional defect present that allows mixing, babies with transposition of the great arteries may nothave enough oxygen in the bloodstream to meet the body's demands.

Even when a significant amount of mixing of oxygen-poor (blue) and oxygen-rich (red) bloodoccurs, other problems may be present. The left ventricle, which in TGA is connected to thepulmonary artery, is usually the stronger of the two ventricles since it normally has to generate a lotof force to pump blood to the body. The right ventricle, connected to the aorta in TGA, is consideredthe weaker of the two ventricles and may not be able to pump blood efficiently to the body. As a

result, it will enlarge under the strain.


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A patent ductus arteriosus (another type of congenital heart defect) will allow mixing ofoxygen-poor (blue) and oxygen-rich (red) blood through the connection between the aorta andpulmonary artery. The "purple" blood that results from this mixing is beneficial, providing small, ifnot normal, amounts of oxygen to the body.

2. PREDISPOSITION AND EPIDEMIOLOGYThe heart is forming during the first eight weeks of fetal development. The problem occurs in

the middle of these weeks, allowing the aorta and pulmonary artery to be attached to the incorrectchamber. Some congenital heart defects may have a genetic link, either occurring due to a defect ina gene, a chromosome abnormality or environmental exposure, causing heart problems to occurmore often in certain families. Most of the time this heart defect occurs sporadically (by chance),with no clear reason for its development.

The epidemiology of TGA are :

Transposition is the most common cyanotic congenital heart lesion presenting in theneonate.

The overall annual incidence is 20-30 per 100,000 live births. It is more common in males than females, with a ratio of about 3:1. Transposition is rarely associated with syndromes or extracardiac malformationsFactors in the mother that may increase the risk of this condition include: Age over 40 Alcoholism Diabetes Poor nutrition during pregnancy (prenatal nutrition) Rubella or other viral illness during pregnancya. Frequency

Despite its overall low prevalence, transposition of the great arteries is the most commonetiology for cyanotic congenital heart disease in the newborn.1 This lesion presents in 5-7%of all patients with congenital heart disease. The overall annual incidence is 20-30 per100,000 live births, and inheritance is multifactorial. Transposition of the great arteries isisolated in 90% of patients and is rarely associated with syndromes or extracardiacmalformations. This congenital heart defect is more common in infants of diabetic mothers.

b. Mortality/MorbidityThe mortality rate in untreated patients is approximately 30% in the first week, 50% in thefirst month, and 90% by the end of the first year. With improved diagnostic, medical, andsurgical techniques, the overall short-term and midterm survival rate exceeds 90%. Long-term complications are secondary to prolonged cyanosis and include polycythemia and

hyperviscosity syndrome. These patients may develop headache, decreased exercisetolerance, and stroke. Thrombocytopenia is common in patients with cyanotic congenitalheart disease leading to bleeding complications. Patients with a large ventricular septaldefect, a patent ductus arteriosus, or both may have an early predilection for congestiveheart failure, as pulmonary vascular resistance falls with increasing age. Heart failure may bemitigated in those patients with left ventricular outflow tract (pulmonary) stenosis.A small percentage (approximately 5%) of patients with transposition of the great arteries(and often a ventricular septal defect) develop accelerated pulmonary vascular obstructivedisease and progressive cyanosis despite surgical repair or palliation. Long-term survival inthis subgroup is particularly poor.

c. RaceNo racial predilection is known.
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d. SexTGA has a 60-70% male predominance.

e. AgePatients with TGA usually present with cyanosis in the newborn period, but clinicalmanifestations and courses are influenced predominantly by the degree of intercirculatory

mixing.

3. PATHOPHYSIOLOGYSystemic and pulmonary circulations are

completely separated. After returning to the right heart,desaturated systemic venous blood is pumped into thesystemic circulation without being oxygenated in thelungs; oxygenated blood entering the left heart goes backto the lungs rather than to the rest of the body. This

anomaly is not compatible with life unless desaturatedand oxygenated blood can mix through openings at oneor more levels. The pulmonary and systemic circulationsfunction in parallel, rather than in series. Oxygenatedpulmonary venous blood returns to the left atrium andleft ventricle but is recirculated to the pulmonary vascularbed via the abnormal pulmonary arterial connection to

the left ventricle. Deoxygenated systemic venous blood returns to the right atrium and rightventricle where it is subsequently pumped to the systemic circulation, effectively bypassing thelungs. This parallel circulatory arrangement results in a deficient oxygen supply to the tissues and anexcessive right and left ventricular workload. It is incompatible with prolonged survival unless mixing

of oxygenated and deoxygenated blood occurs at some anatomic level. The following are 3 commonanatomic sites for mixing of oxygenated and deoxygenated blood in transposition of the greatarteries: Atrial septal defect, Ventricular septal defect, and Patent Ductus Arteriosus

4. CLINICAL MANIFESTATIONa. History Infants with transposition of the great arteries (TGA) are usually born at term, with cyanosis

apparent within hours of birth. The clinical course and manifestations depend on the extent of intercirculatory mixing and

the presence of associated anatomic lesions.o Transposition of the great arteries with intact ventricular septum: Prominent and

progressive cyanosis within the first 24 hours of life is the usual finding in infants.o Transposition of the great arteries with large ventricular septal defect

Infants may not initially manifest symptoms of heart disease, although mildcyanosis (particularly when crying) is often noted.

Signs of congestive heart failure (tachypnea, tachycardia, diaphoresis, andfailure to gain weight) may become evident over the first 3-6 weeks aspulmonary blood flow increases.

o Transposition of the great arteries with ventricular septal defect and left ventricularoutflow tract obstruction

Infants often present with extreme cyanosis at birth, proportional to thedegree of left ventricular (pulmonary) outflow tract obstruction.
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The clinical history may be similar to that of an infant with tetralogy ofFallot.

o Transposition of the great arteries with ventricular septal defect and pulmonaryvascular obstructive disease

Progressively advancing pulmonary vascular obstructive disease can preventthis rare subgroup of patients from developing symptoms of congestiveheart failure, despite a large ventricular septal defect.

Most often, patients present with progressive cyanosis, despite an earlysuccessful palliative procedure.

b. PhysicalNewborns with transposition of the great arteries are usually well developed, without

dysmorphic features. Physical findings at presentation depend on the presence of associated lesions.

Transposition of the great arteries with intact ventricular septumo Infants typically present with progressive central (perioral and periorbital) cyanosis.o Other than cyanosis, the physical examination is often unremarkable.

Transposition of the great arteries with large ventricular septal defecto Cyanosis may be mild initially, although it is usually more apparent with stress or

crying.o Upon presentation, infants often have an increased right ventricular impulse, a

prominent grade 3-4/6 holosystolic murmur, third heart sound, mid-diastolicrumble, and a gallop rhythm.

o Hepatomegaly may be present. Transposition of the great arteries with ventricular septal defect and left ventricular outflow

tract obstruction

o Cyanosis is prominent at birth, and the findings are similar to those of infants withtetralogy of Fallot.o A single, or narrowly split, diminished second heart sound and a grade 2-3/6 systolic

ejection murmur may be present.o Hepatomegaly is rare.

Transposition of the great arteries with ventricular septal defect and pulmonary vascularobstructive disease

o Progressive pulmonary vascular obstructive disease is not always evident fromphysical examination findings.

o Cyanosis is usually present and can progress despite palliative therapy in thenewborn period.

oNo murmur (despite the ventricular septal defect) or early short systolic ejectionsounds are heard.

o The second heart sound is often single, with increased intensity.o In later childhood or adolescence, a high-pitched, blowing, early decrescendo

diastolic murmur of pulmonary insufficiency and a blowing apical murmur of mitralinsufficiency are evident.

5. DIAGNOSISA pediatric cardiologist and/or a neonatologist may be involved in your child's care. A pediatric

cardiologist specializes in the diagnosis and medical management of congenital heart defects, as well

as heart problems that may develop later in childhood. A neonatologist specializes in illnessesaffecting newborns, both premature and full-term. Cyanosis is the major indication that there is a
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problem with your newborn. Your child's physician may also have heard a heart murmur during aphysical examination. A heart murmur is simply a noise caused by the turbulence of blood flowingthrough the openings that allow the blood to mix.

Other diagnostic tests are needed to help with the diagnosis, and may include the following:Chest X-ray A diagnostic test that uses invisible electromagnetic energy beams to

produce images of internal tissues, bones, and organs onto film.In the normal anatomy, the aorta is anterior to and at the right of the pulmonaryartery . In transposition of the great arteries, the pulmonary artery is situated to theright of its normal location and is obscured by the aorta on frontal chest radiographs.This malposition, in association with stress-induced thymic atrophy and hyperinflatedlungs, results in the apparent narrowing of the superior mediastinum on radiographs,the most consistent sign of transposition of the great arteries. The cardiovascularsilhouette varies from normal in the first few days after birth to enlarged and globular,with the classic egg on a string appearance.

Electrocardiogram (ECG or EKG) A test that records the electrical activity of the heart,shows abnormal rhythms (arrhythmias or dysrhythmias) and detects heart musclestress.

Echocardiogram (echo) A procedure that evaluates the structure and function of theheart by using sound waves, recorded on an electronic sensor, that produce a movingpicture of the heart and heart valves.

Cardiac Catheterization A procedure that gives very detailed information about thestructures inside the heart. Under sedation, a small, thin, flexible tube (catheter) isinserted into a blood vessel in the groin and guided to the inside of the heart. Bloodpressure and oxygen measurements are taken in the four chambers of the heart, as wellas in the pulmonary artery and aorta. Contrast dye is injected to more clearly visualizethe structures inside the heart.Cardiac Magnetic Resonance Imaging (MRI) A non-invasive test that uses three-dimensional imaging technology produced by magnets to accurately determine bloodflow and functioning of the heart as it is working.


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6. TREATMENTSpecific treatment for transposition of the great arteries will be determined by physician

based on:

child's age, overall health and medical historyextent of the diseasechild's tolerance for specific medications, procedures or therapieshow child's doctor expects the disease to progressopinion or preferenceThe children most likely will be admitted to the intensive care unit (ICU) or special care

nursery once symptoms are noted. Initially, your child may be placed on oxygen or a ventilator toassist his/her breathing. Intravenous (IV) medications may be given to help the heart and lungsfunction more efficiently.

Other important aspects of initial treatment include the following:A cardiac catheterization procedure can be used as a diagnostic procedure, as well as an

initial treatment procedure for some heart defects. A cardiac catheterization procedure willusually be performed to evaluate the defect(s) and the amount of blood that is mixing.As part of the cardiac catheterization, a procedure called a balloon atrial septostomy may beperformed to improve mixing of oxygen-rich (red) and oxygen-poor (blue) blood.1. A special catheter with a balloon in the tip is used to create an opening in the atrial

septum (wall between the left and right atria).2. The catheter is guided through the foramen ovale (a small opening present in the atrial

septum that closes shortly after birth) and into the left atrium.3. The balloon is inflated.4. The catheter is quickly pulled back through the hole, into the right atrium, enlarging the

hole, allowing blood to mix between the atria.

An intravenous medication called prostaglandin E1 is given to keep the ductus arteriosusfrom closing.

All patients require antibiotic prophylaxis prior to dental and indicated surgicalprocedures in order to reduce the risk of subacute bacterial endocarditisWithin the first 1 to 2 weeks of age, transposition of the great arteries is surgically repaired.

The procedure that accomplishes this is called a "switch," which roughly describes the surgicalprocess. The surgical correction of TGA is carried out through an incision in the middle of the chest.The breast bone is split in the middle and spread apart to expose the heart. A heart-lung machine isused to do the work of the heart while the heart is cooled, stopped, emptied and opened. The aortaand pulmonary arteries are disconnected and reconnected to their proper ventricles. The coronaryarteries must be transferred to the newly positioned aorta as well, or "blue" blood will supply the

muscle of the heart. Associated holes between the chambers of the heart are closed. The heart isthen restarted as the heart-lung machine is withdrawn.
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