Ghai Essential Pediatrics8th

before the right ventricle. The flow of blood from the left ventricle to the right ventricle starts early in systole. When the defect is restrictive, a high pressure gradient is main­ tained between the two ventricles throughout the systole. The murmur, starts early, masking the first sound and continues throughout the systole with almost the same intensity appearing as a pansystolic murmur on auscul­ tation and palpable as a thrill. Toward the end of systole, the declining left ventricularpressure becomes lowerthan the aortic pressure. This results in closure of the aortic valve and occurrence of A2. At this time, however, the left ventricular pressure is still higher than the right ventricular pressure and the left to right shunt continues. The pansystolic murmur, therefore, ends beyond A2 completely masking it (Fig. 15.14). The left to right ventricular shunt occurs during systole at a time when the right ventricle is also contracting and its volume is decreasing. The left to right shunt, therefore, streams to the pulmonaryartery more or lessdirectly.This flow of blood across the normal pulmonary valve results

in an ejection systolic murmur at the pulmonary valve. On the bedside, however, the ejection systolic murmur cannot be separated from the pansystolic murmur. The effect of the ejection systolic murmur is a selective transmission of the

pansystolic murmur to the upper left sternal border, where its ejection character can be recognized since it does not mask

Fig. 15.14: Summary of auscultatory findings in ventricular septal defect. 2 LIS second left interspace; LLSB lower left sternal border; PSM pansystolic murmur

The cardiac silhouette on chest X-ray is left ventricular type with the heart size determined by the size of the left to right shunt (Fig. 15.15). The pulmonary vasculature is increased; aorta appears normal or smaller than normal in size. There may be left atrial enlargement in patients with large left to right shunts. Patients of VSD with a small shunt either because the ventricular defect is small or becauseof the associatedpulmonicstenosis or pulmonary arterial hypertension have a normal sized heart. Echocardiogram shows increased left atrial and ventricular size as well as exaggerated mitral valve

Fig. 15.15: ChestX-ray in ventricular septa! defect. Note the cardiac enlargement mainlyinvolving the left ventricle together with increased lung vasculature as suggested by the size and increased number of end-on vessels in the lung fields

motion. 2D echo can identify the site and size of defect almost all cases (Fig. 15.16), presence or absence of pulmonic stenosis or pulmonary hypertension and associated defects.

Assessment of Severity

If the VSD is small, the left to right shunt murmur continues to be pansystolic but since the shunt is small, the second sound is normally split and the intensity of P2 is normal. There is also absence of the delayed diastolic mitral murmur.

If the VSD is very small it acts as a stenotic area resulting in anejectionsystolicmurmur.This is a relativelycommon cause of systolic murmurs in young infants that disappear because of the spontaneous closure.

If the VSD is large it results in transmission of left ventricular systolic pressure to the right ventricle. The right ventricular pressure increases and the difference in the systolic pressure between the two ventricles decreases. The left to right shunt murmur becomes shorter and softer and on the bedside appears as an ejection systolic murmur.

Patients of VSD may have either hyperkinetic or obstructive pulmonary arterial hypertension. The P2 is accentuated in both. In the former, there is large left to right shunt whereas the latter is associated with a small left to right shunt. In hyperkinetic pulmonary arterial hypertension the cardiac impulse is hyperkinetic with a pansystolic murmur and thrill, widely split and variable S2 with accentuated P2 and a mitral delayed diastolic murmur. Obstructive pulmonary arterial hypertension is associated with a forcible parasternal impulse, the thrill is absent or faint, the systolic murmur is ejection type, the S2 is spilt in inspiration (closely split) with accentuated P2 and there is no mitral murmur.

Thus on the basis of the assessment of physical findings it is possible to separate very small, small, medium sized and large VSD. It is also possible to decide whether there is associated pulmonic stenosis or pulmonary arterial hypertension of the hyperkinetic or obstructive variety. Doppler echo estimates the gradient between the left and right ventricles, thus helping in the assessment of right ventricular and pulmonary artery pressure.

Course and Complications

Patients with VSD have a very variable course. They may develop congestive cardiac failure in infancy which is potentially life threatening. It has been estimated that almost 70% of all ventricular defects become smaller in size. A smaller proportion will disappear entirely. In almost 90% of patients who have spontaneous closure of the defect, it occurs by the age of three years, though it may occur as late as 25 yr or more. Muscular VSD have the highest likelihood of spontaneous closure. Peri­ membranous VSD close with the help of the septal leaflet of the tricuspid valve and sub-pulmonic VSDs often become smaller as the aortic valve prolapses through it. However, this is not a desirable consequence and is often and indication for surgical closure.

Patientsborn with an uncomplicatedVSD may develop pulmonic stenosis due to hypertrophy of the right ventricular infundibulum, develop pulmonary arterial hypertension or rarely develop aortic regurgitation due to prolapse of the right coronary or the non-coronary cusp of the aortic valve. Development of pulmonary arterial hypertension is a dreaded complication since if it is of the obstructive type the patient becomes inoperable.

A patient with a relatively small VSD often lives a life­ time without any symptoms or difficulty. Lastly, the VSD

is the commonest congenital lesion complicated by infective endocarditis. The incidence of infective endocarditis has beenestimated as2/100 patients inafollowup oftenyears, thatis 1/500 patientyears. The incidenceof infectiveendo­ carditisissmall enough thatitisnot anindicationfor oper­ ation in small defects. However, it is important to empha­ size good oral-dental hygiene in all patients with VSD.

Treatment

Medical management consists in control of congestive cardiac failure, treatment of repeated chest infections and prevention and treatment of anemia and infective endocarditis. The patients should be followed carefully to assess the development of pulmonic stenosis, pulmonary arterial hypertension or aortic regurgitation.

Surgical treatment is indicated if: (i) congestive cardiac failure occurs in infancy; (ii) the left to right shunt is large (pulmonary flow more than twice the systemic flow); and (iii) if there is associated pulmonic stenosis, pulmonary arterial hypertension or aortic regurgitation. Surgical treatment is not indicated in patients with a small VSD and in those patients who have developed severe

Disorders of Cardiovascular System -

pulmonary arterial hypertension and significant right to left shunt.

Operative treatment consists in closure of VSD with the use of a patch. The operation is performed through the right atrium. Theoperationcan be done as early asa few months after birth if congestive failure cannot be controlled with medical management. With evidence of pulmonary hypertension, the operation should be performed as early as possible. Modern centers prefer to close VSD surgically in young infants. It is unwise to make the sick infants to wait for a certain weight threshold because most infants with large VSD do not gain weight satisfactorily. Episodes of respiratory infections require hospitalization and are particularly difficult to manage. For sick infants with pneumonia who require mechanical ventilation, surgery is considered after initial control of the infection. Major complications of surgery are: (i) complete heart block, (ii) bifascicular block, and (iii) residual VSD. These complicationsare rare andriskofsurgeryinuncomplicated defects is less than 1% in most centers.

Catheter closure of VSD is best suited for muscular defects in relatively older children (> 8-10 kg). There is a device designed for perimembranous defects as well. However, the risk of complete heart block with the membranous VSD occluder is significant and can occur late after implantation. Device closures of VSD require considerable technical expertise and should be attempted in dedicated centers.

Patent Ductus Arteriosus

Patent ductus arteriosus (PDA) is a communication between the pulmonary artery and the aorta. The aortic attachment of the ductus arteriosus isjust distal to the left subclavian artery. The ductus arteriosus closes func­ tionally and anatomically soon after birth; its persistence is called PDA.

Hemodynamics and Clinical Features

PDA results in a left to right shunt from the aorta to the pulmonary artery. Theflow occurs both during systole and

diastoleasapressuregradientis presentthroughoutthecardiac cycle between the two great arteries, if the pulmonary artery pressure is normal. The flow of blood results in a murmur that starts in systole, after the first sound, and reaches a peak at the second sound. The murmur then diminishes in intensity and is audible during only a part of the diastole. Thus, it is a continuous murmur.

The PDA results in a systolic as well as diastolic overloading of the pulmonary artery. The increased flow after passing through the lungs reaches the left atrium. To accommodate the flow the left atrium enlarges in size. The increased volume of blood reaching the left atrium enters the left ventricle in diastole, across a normal mitral valve. The passage of this increased flow across the mitral valve results in an accentuatedfirst sound as well as a mitral

delayed diastolic murmur. The large volume of blood in the left ventricle causes a prolongation of the left ventricular systole and an increase in the size of the left ventricle to accommodate the extra volume. The prolonged left ventricular systole results in delayed closure of the aortic valve and a late A2. With large left to right shunts, the S2

may be paradoxically split.

The large left ventricular volume ejected into the aorta results in dilatation of the ascending aorta. A dilated ascending aorta results in an aortic ejection click, which is audible all over the precordium and precedes the start of the continuous murmur. The large volume of blood from the left ventricle passing through a normal aortic valve results in an aortic ejection systolic murmur, however, on the bedside it is drowned by the loud continuous murmur and is usually not made out as a separate murmur.

Patients with PDA may become symptomatic in early life and develop congestive cardiac failure around 6-10 weeks of age. Older children give history of effort intolerance, palpitationandfrequent chest infections. The flow from the aorta to the pulmonary artery is a leak from the systemic flow. This results in a wide pulse pressure and manyof the signs of wide pulse pressure enumerated earlier in association with aortic regurgitation are present in patients who have a PDA. On the bedside, presence of prominent carotid pulsations in a patient with features of a left to right shunt suggests the presence of PDA. The cardiacimpulseishyperkinetic witha leftventriculartype of apex. A systolic or a continuous thrill may be palpable at the second left interspace. Thefirst sound is accentuated

and the second narrowly or paradoxically split with large left to right shunts. With small shunts the second sound is normally split. The P2 is louder thannormal. It is difficult to evaluate the S2 in patients with PDA, since the maximum intensity of the continuous murmur occurs at S2 and tends to mask the S2. The continuous murmur indicates presence of both a systolic as well as a diastolic difference in pressure between the aorta and pulmonary artery, thus excluding significant pulmonary arterial hypertension. The murmur starts after the first sound and

reaches the peak at the second sound. The murmur then

diminishes in intensity and is audible only during a part of the diastole. The peak at the second sound differentiates the PDA murmur from other causes of a continuous murmur. Additionally, the systolic portion of the murmur is very grating and rough. It appears to be broken into multiple systolic sounds-the multiple clicks. The murmur is best heard at the second left interspace and is also well heard below the left clavicle where it maintains its continuous character. There is a third sound at the apex, followed by a delayed diastolic murmur in large shw1ts (Fig. 15.17).

The electrocardiogram shows normal axis with left ventricular dominance or hypertrophy. Deep Q waves in left chest leads with tall T waves are characteristic of volume overloading of left ventricle. The roentgenogram (Fig. 15.18) exhibits cardiac enlargement with a left

ventricular silhouette; cardiac sizedepends on thesizeof theleftto rightshw1t. Theremaybe leftatrialenlargement. The ascending aorta and theaorticknuckle are prominent; pulmonary vasculature is plethoric. 20 echocardiogram

Patent Ductus

ECG

Fig. 15.17: Summary of auscultatory findings in patent ductus arteriosus (PDA) CONT continuous; DDM delayed diastolic murmur; ESM ejection systolic murmur; M1 mitral component of first sound

fig. 15.18: Chest X-ray in an adolescent with a large patent ductus arteriosus. Note the enlargement of the aorta with a prominent aortic knuckle, large main pulmonary artery-left pulmonary artery and increased vasculature. There is no X-ray evidence of cardiac enlargement

confirms the diagnosis and measures size of PDA and identify its hemodynamic consequences. It is possible to obtain a semiquantitative assessment of shunt size and assess pulmonary artery pressure (Fig. 15.19).

Fig. 15.19: Echocardiography in patent ductus arterious (PDA). The frame on the left is a cross sectional two dimensional view of the PDA and the frame on the right is a color flow image. The red flow represents flow reversal in the descending thoracic aorta as a result of a left to right shunt across the PDA. Ao aorta; MPA main pulmonary artery

Assessment of Severity

Theevaluationof thesize of the left to right shunt depends on a number of features: (i) the larger the heart size the larger the left to right shunt; (ii) absence of the third sound and delayeddiastolicmurmur indicatesa smallleft toright shunt. Presence of the third sound indicates a moderate left to right shunt whereas an audible delayed diastolic murmur suggests a large left to right shunt; (iii) the wider the pulse pressure the larger the shunt.

Course and Complications

Neonates and infants have pulmonary hypertension at birth. The regression of pulmonary hypertension occurs slowly in the presence of PDA. The PDA murmur, therefore, is an ejection systolic murmur to start with (like in VSD) and assumes the continuous character only some weeks or months later. Congestive cardiac failure may occur within the first six weeks of life; cardiac failure can be controlled medically in uncomplicated patients. Patients with PDA develop pulmonary arterial hypertension earlier than VSD.

PDA may beassociatedwith hyperkineticor obstructive pulmonary arterial hypertension as in VSD. In both situations the murmur tends to lose the diastolic component and the P2 is accentuated. The hyperkinetic pulmonary hypertension is associated with a large heart and mitral delayed diastolic murmur whereas the obstructive variety is accompanied with a normal heart size and absence of the mitral diastolic murmur. With severe pulmonary arterial hypertension and a right to left shunt through a PDA, the normal splitting of S2 is

Disorders of Cardiovascular System -

maintained but the murmur disappears and the patients develop differential cyanosis.

Differential Diagnosis

The differential diagnosis of PDA includes conditions capableofgivingacontinuousmurmurovertheprecordium. In addition, combination of a pansystolic murmur with an ear1ydiastolic murmur, which are partly superimposedon each other, may simulate a continuous murmur over the precordium.Differentialdiagnosisofacontinuousmurmur includes: (i) coronary arteriovenous fistula; (ii) ruptured sinus of Valsalva fistulae into the right side, (iii) aortopulmonarywindow; (iv)systemicarteriovenousfistula over the chest; (v) bronchial collateral murmurs; (vi) pulmonaryarteriovenousfistula; (vii) peripheralpulmonic stenosis; (viii) venous hum including that associated with total anomalous pulmonary venous connection; and (ix) small atrial septal defect associated with mitral stenosis (Lutembacher syndrome). The impression of continuous murmurduetoacombinationofapansystolicmurmurand regurgitantdiastolicmurmuroccursmostcommonlyinVSD associated with aortic regurgitation.

Treatment

A large PDA is better tolerated by term newborns when compared to premature newborns. Premature newborns with hemodynamically significant PDA that results in heart failure, respiratory distress or necrotizing enterocolitis require prompt management. Indomethacin or ibuprofen is likely to be effective before the age of 2- weeks in preterm newborns and is unlikely to be useful in term babies. The dose of indomethacin is 0.2 mg/kg/ dose, orally, every 12-24 hr for three doses (second and third doses are at 0.1 mg/kg/dose for <48 hr-old and 0.25 mg/kg/dose for >7-days-old). Hepatic or renal insufficiencyandbleeding tendency are contraindications. Newborns not responding to these agents require surgical ligation. The PDA in term infantsmay closespontaneously as late as one month after birth and it is worth waiting if the duct is large unless the heart failure is refractory.

Large PDA may result in congestive cardiac failure in infancy. Echocardiography allows ready confirmation of the diagnosis and estimation of hemodynamic severity of the PDA. Catheter based treatment (occlusive devices or coils) is now realistic in most patients with PDA (Fig. 15.20). They are technically challenging in small infants especially those <5 kg and should be performed incenterswithexperience. Indications forsurgeryfor PDA include small infants with large ducts, preterm infants, and ducts that are very large (larger than the size of available devices) or in situations where surgery is the only affordable option (occlusive devices cost 2-3 time more than surgery).

Patients who have a PDA with pulmonary arterial hypertension are considered inoperable if a right to left shunt has appeared because of pulmonary arterial

Fig. 15.20: Angiograms (aortogram) obtained before and after coil occlusion of a moderately large patent ductus arteriosus (PDA) showing complete occlusion

hypertension. Since theright toleft shuntthroughthe POA flows down the descending aorta, cyanosis is present in toes but not in fingers. This is called differential cyanosis and is characteristic of POA with pulmonary arterial hypertension and right to left shunt.

CYANOTIC HEART DISEASE

Tetralogy of Fallot

Among cyanotic CHO, tetralogy of Fallot (TOF) has a relatively favorable natural history that allows survival beyond infancy in about 75% of cases. As a result it is the most commoncyanotic CHOencounteredbeyondthe age of 1-yr constituting almost 75% of all blue patients. The physiology is that of VSO with pulmonic stenosis, as

described above. Anatomically it is characterized by the classic tetrad: severe right ventricle outflow obstruction, large VSO, aorta that overrides the VSO and right ventricular hypertrophy. Multiple anatomical variations of TOF exist, which have a bearing on treatment (Table 15.15).

Hemodynamics

Physiologically the pulmonic stenosis causes concentric rightventricularhypertrophywithout cardiacenlargement and an increase in right ventricular pressure (Fig. 15.21). When the right ventricular pressure is as high as the left ventricular or the aortic pressure, a right to left shunt appears to decompress the right ventricle. Once the right and left ventricular pressures have become identical, increasing severity of pulmonic stenosis reduces the flow of blood into the pulmonary artery and increases the right to left shunt. As the systolic pressures between the two ventriclesareidenticalthereislittleor noleft to right shunt and the VSO is silent. The right to left shunt is also silent since it occurs at insignificant difference in pressure between the right ventricle and the aorta. The flow from the rightventricleinto thepulmonaryartery occursacross the pulmonic stenosis producing an ejection systolic murmur. Themore severe the pulmonic stenosis, the less theflow into thepulmonary artery and the bigger theright to left shunt. Thus the more severe the pulmonic stenosis, the shorter the ejection systolic murmur and the more the cyanosis. Thus the severity ofcyanosis is directly proportional to the severity of pulmonic stenosis, but the intensity of the systolic murmur is inversely related to the severity ofpulmonic stenosis. The VSO of TOF is always large enough to allow

Implications

Severe stenosis manifests early; annular narrowing requires correction with transannular patch with significant late sequelae; predominant valvar stenosis may allow palliation with balloon valvotomy in selected cases

Small branch PA may not allow surgical correction at early age; absent branch PA require placement of PA conduit

Severe airway compression; manifestations chiefly respiratory

Surgical approach needs to be tailored

Abnormal vessel comes in way of corrective surgery

Patent foramen ovale often helpful in early post­ operative period; enables recovery

Collaterals need to be defined and closed if their supply overlaps with the native pulmonary artery supply

free exit to the right to left shunt. Since the right ventricle is effectively decompressed bythe VSD, congestive failure never occurs in TOF. The exceptions to this rule are

(i) anemia; (ii) infective endocarditis; (iii) systemic hypertension; (iv) unrelated myocarditis complicating TOF; and (v) aortic or pulmonary valve regurgitation.

The right ventricular outflow obstruction results in a delay in the P2. Since the pulmonary artery pressure is reduced, the P2 is also reduced in intensity. The late and soft P2 is generally inaudible in TOF. The S2 is, therefore, single and the audible sound is A2. Since the aorta is somewhat anteriorly displaced, the audible single A2 is quite loud. The ascending aorta in TOF is large and may result in an aortic ejection click. On auscultation, the diastolic intervalis completely clear in TOF as there is no third or fourth sound or a diastolic murmur.

Concentric right ventricular hypertrophy reduces the distensibility of the right ventricle during diastole. The rightatrialcontraction at the end ofdiastolecauses a rela­ tively large 'a' waves. Although the 'a' waves are pro­ minent in the jugular venous pulse, they are not too tall unless right ventricular dysfunction is present.

Clinical Features

Patients with TOF may become symptomatic any time after birth. Neonatesas well as infants may developanoxic spells (paroxysmal attacks of dyspnea). Cyanosis may be present from birth or make its appearance some yearsafter birth. The commonest symptoms are dyspnea on exertion and exercise intolerance. The patients assume a sitting posture-squatting-as soon as they get dyspneic. Although squatting is not specific for TOF, it is the commonest congenital lesion in which squatting is noted.

Anoxic spells occur predominantly after waking up or following exertion. The child starts crying, becomes dyspneic, bluer than before and may lose consciousness. Convulsions may occur. The frequency varies from once in a few days to numerous attacks every day.

Physical examination discloses cyanosis, clubbing, slightly prominent 'a' waves in the jugular venous pulse, normal sized heart with a mild parasternal impulse, a systolic thrill in less than 30% patients, normal first sound, single second sound and an ejection systolic murmur which ends before the audible single second sound (Fig. 15.22). The electrocardiogram in TOF shows right axis deviation with right ventricular hypertrophy. The 'T'

Fig. 15.22: Summary of auscultatory findings in tetralogy of Fallot. X systolic click. PS pulmonic stenosis

waves are usually inverted in right precordial leads; P pulmonale may be present, but isuncommon. Vl may show

pure 'R' but transition to R/S complex occurs at V2. The chest X-ray shows a normal sized heart with upturned apex suggestive of right ventricular hypertrophy. The

absence of main pulmonary artery segment gives it the shape described as Coeur en Sabot. The aorta is enlarged

and right aortic arch is present in 30% cases. The right aortic arch in a posteroanterior thoracic roentgenograrn is easily recognized by its concave impression on the right side of trachea. The pulmonary fields are oligemic (Fig. 15.23).

The murmur shortens and the cyanosis increases with increasing severity of the right ventricular outflow tract obstruction. Paroxysmal attacks of dyspnea can bepresent with mild as well as severe TOF. However, effort intolerance is directly related to the severity.

patient activities. Each attack of paroxysmal dyspnea or anoxic spell is potentially fatal. Anemia, by decreasing the oxygen carrying capacity of blood, reduces the exercise tolerance still further. It can result in cardiac enlargement

and congestive cardiac failure making diagnosis difficult. Patients are prone to infective endocarditis.

Neurological complications occurfrequently. Anoxicinfarction

in the central nervous system may occur during an anoxic spell and result in hemiplegia. Paradoxicnl e111bolis111 to

central nervous system and venous thrombosis due to

sluggish circulation from polycythemia can also result in hemiplegia. Brain abscess is not an infrequent complication.

It should be suspected in any cyanotic patient presenting with irritability, headache, convulsions, vomiting with or without fever and neurological deficit. The fundus need expertevaluationsince polycythemiaresultsin congested retina and recognition of papilledema is difficult.

Diagnosis

The diagnosis of TOF is confirmed by echocardiography; cardiac catheterization is seldom necessary. Additional specific information required for surgical decision is also obtained throughechocardiography. Cardiac catheterization or CT/MRI may be requiredin older children with limited echo windows.

Course and Complications

Patients with TOF are subject to many difficulties. The pulmonic stenosis becomesprogressively severe with age. The dyspnea and increasing exercise intolerance limit

Fig. 15.23: Chest X-ray in Tetralogy of Fallot with right aortic arch. The key findings are reduced lung vasculature as suggested by the dark lung fields, normal heart size, concavityin the region of the main pulmonaryartery(pulmonarybay). This X-ray also shows a rightaortic arch. The arrow indicates the indentation of the right arch on the right side of the trachea

Treatment

The medical management of TOF is limited to prevention and management of complications and correction of anemia. Oral beta-blockers help prevent cyanotic spells. Maximally tolerated doses of propranolol ranging from 0.5-1.5mg/kg/doseshould be administered. Iron supple­ mentation is recommended for all infants and young children with TOF. The management of anoxic spells is indicated in Table 15.16.

Definitive surgery for TOF involves closure of the VSD and relief of the RVOT obstruction. Often the relief of the RVOT obstruction involves the placement of a trans­ annularpatchacross the pulmonaryvalveand valvectomy resulting in severe pulmonary regurgitation. There is growing emphasis on retaining the pulmonary valve during initial repair to prevent pulmonary regurgitation and its major late consequences (RV dilation, arrhythmia, heart failure and sudden death). However, this is not often possible if the pulmonary annulus is small.

Although definitive operation is feasible in young infants, some centers opt for palliative options initially. This is typically done through the Blalock-Taussig shunt, which consists of subclavian artery-pulmonary artery anastomosis using a Goretex graft. Alternatives include balloon dilation of the pulmonary valve or stenting of the patent arterial duct (if present). A number of longterm concerns have emerged in survivors of TOF repair 2-3 decades after the operation. These include heart failure andrisk of ventricular tachyarrhythrnias as aresult ofright ventricular dilation that results from chronic pulmonary regurgitation, as well as the scar on the right ventricle if ventriculotomy has been done during operation.

Tricuspid Atresia

Congenital absence of the tricuspid valve is called tricus­ pid atresia (Fig. 15.24). The right ventricle is hypoplastic. The inflow portion is absent. The hemodynamics is described above; see single ventricle physiology.

Clinical Features

Clinical presentation depends on the state of pulmonary flow that may be diminished or increased. Clinically, pati­ ents who have diminished pulmonary blood flow constitute90%and symptoms and physical signs are more or less identical to TOF. Features suggesting tricuspid atresia are (i) left ventricular type of apical impulse; (ii) prominent large a waves in jugular venous pulse; (iii) enlarged liver withpresystolicpulsations (a waves); and (iv) the electrocardiogram which is characterized by left axis deviation andleftventricularhypertrophy. The mean QRS axis is around -45°. Patients with tricuspid atresia and increasedpulmonary blood flow cannotbe diagnosed accurately clinically.

Course

PatientswithtricuspidatresiafollowacoursesimilartoTOF. Theyarecyanosedatbirth. Anoxicspellsandsquattingmay be present; patients are relatively sicker than TOF.

Treatment

Tricuspid atresia is categorized as 'single ventricle physiology' and management is on similar lines.

Ebstein Anomaly

An unusual and rare cyanotic congenital heart disease with diminished pulmonary blood flow results from an abnormality of the tricuspid valve. The posterior as well as the septal leaflet of the tricuspid valve is displaced downwards to a variable extent. The result is an

attachment to the posterior wall of the right ventricle. In addition, the leaflets are malformed and fused resulting in obstruction to flow of blood into the right ventricle. The portion of the right ventricle above the leaflet attach­ ment thins out and is called atrialized right ventricle. The right ventricular contraction is also abnormal.

Hemodynamics

The tricuspid valve anomaly results in obstruction to forward flow of blood as well as regurgitation of blood from the right ventricle into the right atrium. In addition, there is a large part of the right ventricle that is atrialized as a result of downward displacement of the tricuspid valve attachment. This atrialized right ventricle contracts with the rest of the ventricle and does not allow effective forward flow into the pulmonary circulation. The right atrium progressively dilates, to accommodate the extra volume. The foramen ovale may be patent or there is an atrial septal defect allowing a right to left shunt to occur. This results in cyanosis. The greater the tricuspid valve displacement, the more the cyanosis.

Clinical Features

Patients presentwith historyofcyanosis, effortintolerance and fatigue. They may also give history suggestive of paroxysmal attacks of tachycardia. Cyanosis varies from slight to severe; clubbing is present. The jugular venous pulse may show a dominant 'V' wave but there is usually no venous engorgement. The precordium is quiet with a left ventricular apical impulse. A systolic thrill may be

palpable at the left sternal border. The first sound is split, however, the tricuspid component cannot be made out, resulting in a single, normally audible first sound. The abnormaltricuspid valve may produce a mid systolic click. The second sound is widely split, but variable with a soft pulmonic component. A right ventricular third sound and/or a right atrial fourth sound may be audible. The abnormal tricuspid valve may produce a mid systolic click. Thus, triple or quadruple sounds are usually heard. The systolic murmur may be a mid-systolic ejection murmur or a loud pansystolic murmur. There is also a short tricuspid delayed diastolic murmur. Both the systolic and the diastolic murmur produced at the tricuspid valve have a scratchy character, not unlike a pericardia! friction rub.

The electrocardiogram is characteristic in that it shows prominent 'P' waves and right bundle branch block. Char­ acteristically the 'R' wave in Vl does not exceed 7 mm. The lead V6 generally shows a relatively tall 'R' wave as well as a broad 'S' wave. Wolff Parkinson White type of conduction abnormality may be seen in the electrocardio­ gram (Fig. 15.25). The X-ray shows cardiac enlargement due to right atrial and right ventricular enlargement. The main pulmonary artery segment may be prominent and the aortic knuckle small (Fig. 15.26). The pulmonary vasculature is diminished. Two dimension echocardio­ gram is diagnostic as it outlines the displaced tricuspid valve (Fig. 15.27).

Diagnosis and Treatment

The diagnosis can be easilyconfirmed by echocardiography, which can not only identify the anomaly but also indicate the severity. Surgical treatment consists in obliterating the atrialized portion of the right ventricle and repairing the tricuspid valve.

Transpositon of Great Vessels i

Transposition of great vessels (TGA) is defined as aorta arisingfrom the right ventricle and pulmonary arteryfrom the left ventricle. By definition, therefore, the great vessels (aorta and the pulmonary artery)arise from inappropriate ventricles, both of which must be present and identifiable. In TGA the aorta generally lies anterior and to the right of the pulmonary artery. For this reason, this is also referred to as D-TGA. Since the systemic and pulmonary circulations are separate, survival depends on the presence of atrial, ventricular or aortopulmonary communications. TGA is classified into (a) with intact ventricular septum, and (b) with VSD. The latter group is further subdivided into cases with and without pulmonic stenosis. Patients with complete TGA, VSD and pulmonic stenosis are included in tetralogy physiology.

In patients with TGAtheoxygenatedpulmonaryvenous blood recirculates in the lungswhereasthesystemicvenous blood recirculates in the systemic circulation. The pul­ monary artery saturation is thus always higher than the aortic saturation. Survival depends on the mixing available

V3 v.

'2,I T'i:Y+

I"'-,----·.i -.J .,j.j..._,._ - -

Fig. 15.25: Electrocardiogramtypical of Ebstein anomaly. Right bundle branch block with 'R' of less than 7 mm is present

Fig. 15.26: Chest X-ray in Ebstein anomaly. There is considerable enlargement of the right atrium. The lung vascularity is reduced

Fig. 15.27: Apical four chamber view from a patient with Ebstein anomaly. Note the downward displacement of the septal leaflet of the tricuspidvalve(arrow). aRV: atriaized right ventricle, LA: left atrium; LV: left ventricle; RA: right atrium; RV: right ventricle