Patient with slowly progressive prosthetic valve obstruction or severe paravalvar leak may present with progressive exertional dyspnoea while presentation with acute pulmonary edema may be the situation in case of prosthetic valve thrombosis. Embolic episodes can also occur with prosthetic valve thrombosis.

Echocardiography, both transthoracic and transesophageal, are the important modalities of prosthetic valve evaluation. Image intensifier fluroscopy when available, is useful in visualising the movement of the valve discs or balls if they are radio-opaque. Abnormal movements of the valve stents or cage suggest partial dehisence of the prosthesis due to slipping of sutures and may be an ominous sign.

Though echocardiography is an important modality for evaluation of prosthetic valve, dense shadows in case of mechanical prosthesis can make evaluation of structures and flows behind the valve difficult. Similarly small thrombi or vegetations attached to the valves may also be missed. Evaluation of the left atrial side of the prosthesis and mitral regurgitation necessitates transesophageal echocardiography in case of prosthetic mitral valve. Aortic regurgitation can be picked up well with trans thoracic echocardiogram as the left ventricle is not within the shadow region. Presence of spontaneous echo contrast in the left atrium should also make one suspect mitral prosthetic thrombosis.

The valve gradients across the prosthetic valves are usually higher than normal even for a normally functioning prosthetic valve. A gradient above 10 mm Hg across the mitral and peak gradient more than 40 mm Hg across the aortic valve are significant. Highly sensitive Doppler equipment can detect even the normal closure back flow or seating regurgitation with normally functioning prosthetic valves. Pathologic regurgitation on the other hand is of high velocity with intense aliasing and often along the wall of the left atrium in case of mitral valve (Coanda effect). It is mentioned that sometimes a paravalvar leak due to suture dehisence may be laminar and missed. Rocking abnormal movement of the valve ring or stent will be an indicator in such cases.

Prosthetic valve evaluation should begin in the post operative period with careful documentation of findings including the exact location from which good images are obtained. This is essential to detect changes with time which might indicate prosthetic valve dysfunction. Intra-operative echo if available, will be quite useful.

In a chronic case of valve obstruction, differentiating between thrombus and pannus is important. Pannus is more often seen in the aortic position and thrombus more in the mitral postion. Thrombus is a much more common cause of obstruction than pannus. Pannus is highly echogenic compared to a thrombus. Thrombus is less echogenic and may be mobile. Associated spontaneous echocontrast is another indication of thrombus.

Detecting vegetations over a prosthetic valve is another difficult task requiring familiarity with the normal echoes of the particular valve. Transesophageal echocardiography (TEE) is useful in this regard because of the higher resolution and the ability to image the atrial side of the mitral prosthesis better. TEE is also useful in evaluating valve ring abscess and pseudoaneurysm.

In case of bioprosthetic valves, thickening, calcification or perforation may be noted. Sometimes a flail leaflet may also be picked up on echo.

3D echocardiography is a promising tool in the evaluation of prosthetic valves.

Infective endarteritis is less likely in a very small PDA as well as a large PDA. It is more likely in moderate sized PDAs and small PDAs. Hence there is no role for closing very small PDA without continuous murmur. In PDA infective endarteritis, the vegetations occur either at the pulmonary end of the ductus or in the wall of the pulmonary artery opposite the ductus, where the jet strikes.

Why is neonatal myocardium more prone for cardiac failure?

Contractile elements form 30% of the fetal heart while it forms 60% in the adult. Immature myocytes lack sufficient sarcoplasmic reticulum and mitochondria. Hence the neonatal myocardium is more cardiac failure.

Angina in Eisenmenger PDA

In general angina due to right ventricular ischemia is rarer in Eisenmenger PDA compared to other forms of Eisenmenger syndrome. Angina has been reported in Eisenmenger PDA due to compression of left main coronary artery [Am Heart J. 1993;125:1767-71].

Mitral restenosis with calcification is the common reason for requiring mitral valve replacement later. Other possibilities are inadequate valvotomy and development of progressive mitral regurgitation, which could have developed during the procedure or later on due to recurrence of rheumatic activity.

How will you identify mitral restenosis and differentiate it from inadequate valvotomy? 

Historically there should have been a sustained improvement of at least 2 classes of NYHA for at least 6 months after the mitral valvotomy. Earlier recurrence of symptoms could be due to an inadequate valvotomy. An initial transient improvement is not enough to qualify for a successful valvotomy as even a slight increase in mitral valve area will produce subjective improvement in a patient with critical mitral stenosis and pulmonary congestion. To diagnose mitral restenosis, there should be at least 50% loss of the initial valve area and the absolute valve area should be below 1.5 sq cm. That would be mean that a diagnosis of mild mitral restenosis will not be tenable – mild mitral stenosis being defined as mitral valve area between 1.5 – 2.0 sq cm. Moderate mitral stenosis is defined as mitral valve area between 1.0 to 1.5 sq. cm. Mitral valve area below 1.0 sq cm constitutes critical or severe mitral stenosis. This is the level of obstruction needed to raise the transmitral gradient above 20 mm Hg and left atrial pressure to 25 mm Hg, the threshold for pulmonary edema.

What is chronic rheumatic carditis?

Rheumatic carditis lasting more than 6 months is considered as chronic rheumatic carditis. Evidence of recent streptococcal infection as an essential criteria for the diagnosis of rheumatic carditis cannot be applied in this situation.

What is patient prosthesis mismatch in aortic valve replacement?

An effective orifice area less than 0.7 sq cm per sq m body surface area for the aortic valve is taken as patient prosthesis mismatch in case of aortic valve replacement.

Other causes of heart failure on day 1 are critically obstructed series circulation as in critical aortic stenosis or pulmonary stenosis or obstructed total anomalous pulmonary venous connection (TAPVC) and a poorly mixing parallel circulation as in transposition of great arteries ( TGA).

When the mitral diastolic murmur is not audible despite the presence of severe mitral stenosis, it is called silent mitral stenosis.

Mechanism of silent mitral stenosis

Right ventricular hypertrophy causes clockwise rotation of the heart so that the left ventricle becomes more posterior and the apex is formed by the right ventricle. Hence the mitral diastolic murmur is not heard at the apex. Another reason is the decreased flow across the mitral valve in very severe mitral stenosis diminishing the intensity of the murmur. The decreased mobility of the thick and calcified mitral leaflets in severe calcific mitral stenosis may contribute to the decrease in intensity of the mitral diastolic murmur.

Mechanism of loud first heart sound in mitral stenosis

In severe mitral stenosis, due to elevated left atrial pressure, the closure of the mitral valve is delayed and occurs at a time when the dp/dt of the ventricular pressure tracing is higher. This enhances the intensity of the mitral component of first heart sound. The elevated left atrial pressure also keeps the mitral valve in a more open position at the onset of systole. This would mean a greater closing excursion of the mitral valve, increasing the intensity of the first heart sound. In calcific mitral stenosis, the decreased mobility of the valve leaflets may decrease the intensity of the first heart sound.

Mechanism of wide fixed split in atrial septal defect.

The P2 (pulmonary component of second heart sound) does not move with respiration in atrial septal defect (ASD) because the right ventricular output and pulmonary hang out interval does not change with respiration. Pulmonary hang out interval does not change because the pulmonary circulation is already overloaded by the left to right shunt. Right ventricular output does not change because the change in left to right shunt with respiration balances the change in right ventricular inflow due to change in venous return. In inspiration, when the venous return increases, left to right shunt across the atrial septal defect decreases and vice versa. The split is wide in ASD because the right ventricular emptying is more prolonged due to the volume overload.

Tachypnoea

Tachypnoea is an increase in the rate of respiration.

Hyperpnoea

Hyperpnoea is an increase in depth and rate of respiration.

Hyperventilation

Hyperventilation is an increase in depth and rate of respiration inappropriate to the metabolic need. It can be either or voluntary as in conversion disorders or neurogenic as in central neurogenic hyperventilation.

Pointers of associated mitral valve obstruction in severe aortic regurgitation

Long duration of symptoms, paroxysmal nocturnal dyspnoea, hemptysis and atrial fibrillation are pointers to associated mitral stenosis in a case of severe aortic regurgitation. A loud first heart sound and opening snap will favour associated mitral stenosis than Austin Flint murmur in aortic regurgitation. Orthopnoea can occur in severe mitral stenosis as well as decompensated aortic regurgitation.

What is the most important diagnostic feature of mitral regurgitation?

Apical location of the murmur is the most important feature of mitral regurgitation. Second is the blowing quality in chronic mitral regurgitation (MR). Third is the timing – chronic rheumatic MR is pansystolic while that in mitral valve prolapse can be mid or late systolic. Conduction pattern is variable depending on the etiology. Classical rheumatic MR is conducted to the axilla and back, while that of papillary muscle dysfunction is conducted medially to the base of the heart.

Murmurs are graded depending on their intensity from grade 1 to grade 6, grade 6 being the loudest. Though the presence of thrill is not part of the grading, in general, murmurs of grade 4 and above are associated with a thrill. Grade 1 murmur is very faint while grade 6 murmur can be heard with the stethoscope kept near the chest without actual contact. The grading is often called Levine’s grading though it was described by Harvey and Levine.

Heart failure in acute rheumatic fever

Heart failure in acute rheumatic fever is generally due to acute valvular regurgitations, mostly mitral regurgitation. Even though rheumatic fever causes pancarditis with involvement of pericardium, myocardium and endocardium, it is often the valvular involvement as part of the endocardial involvement which causes heart failure rather than myocardial failure. Hence heart failure without significant valvular involvement is unlikely to be due to acute rheumatic fever and is more likely to be due to some other form of myocarditis.

Aortic stenosis murmur and heart failure

When the stroke volume falls in heart failure, the intensity of aortic stenosis murmur falls and may even be inaudible. This is why critical aortic stenosis comes in the differential diagnosis of dilated cardiomyopathy. Even the Doppler gradient across the aortic valve may be low in such cases and may require inotropic stimulation to assess the true gradient and severity of aortic stenosis.

Aortic ejection click in Tetralogy of Fallot has a phasic nature with expiratory augmentation similar to that of the phasic ejection click in valvar pulmonary stenosis.

What is the mechanism of phasic ejection click in valvar pulmonary stenosis?

During inspiration the systemic venous return increases and enhances the right ventricular filling. This elevates the right ventricular end diastolic pressure causing a cephalad excursion of the pulmonary valve at the end of diastole. Hence the opening movement during systole is less as the valve is already partially domed at the end of diastole. In expiration the right ventricular end diastolic pressures are lower and presystolic doming of pulmonary valve does not occur. Hence the systolic excursion of pulmonary valve is more in systole and produces a prominent click. The click is nearer to first heart sound in inspiration, apparently fusing with it and moves away from the first heart sound in expiration.

What is hemodynamic vise?

The vertical vein in total anomalous pulmonary venous connection passes between the pulmonary artery and the left bronchus and gets compressed when the pulmonary artery pressure goes up. This produces pulmonary venous obstruction and increased pulmonary venous pressure, which in turn causes further elevation of pulmonary artery pressure leading to enhanced compression of the vertical vein. A vicious cycle of increasing pulmonary venous and arterial pressures is setup.

What is the classical chest x-ray finding in TAPVC?

The classical chest x-ray finding in total anomalous pulmonary venous connection (TAPVC) is “snow man in snow storm appearance”. It is also called “figure of eight appearance” and “cottage loaf appearance”. The lower part of the figure of eight is the heart and the upper part is contributed by the vertical vein on the left and dilated superior vena cava on the right side. The dilated left brachiocephalic vein forms the superior link. The snow man in snow storm description is because the lung fields are congested, mimicking snow storm.

Differential pulmonary blood flow in TGA

The orientation of right ventricular outflow is towards the right pulmonary artery in transposition of great arteries (TGA) and causes increased blood flow in the right lung.

Dilated pulmonary arteries in TOF with absent pulmonary valve

In Tetralogy with absent pulmonary valve, the main pulmonary artery and intramediastinal portion of right and left pulmonary arteries are dilated. Hence the dilatation of right and left pulmonary arteries may not be evident on chest x-ray and visualised only on pulmonary angiogram. The reason for dilatation of the intramediastinal portion alone is thought to be because this region is not surrounded by lungs.

What is the feature of ductal (PDA) calcification of x-ray chest?

Calicified patent ductus arteriosus produces an inverted Y shaped pattern of calcification on x-ray chest PA view.

Valvular stenotic lesions or regurgitations
Coarctation of aorta
Cyanotic congenital heart disease

Breath holding spell

Breath holding spell has a precipiating factor which causes the child to cry incessantly and this is followed by breath holding. Breath holding does not occur abruptly. Child may become cyanosed after prolonged breath holding which may also lead on to seizures.

Williams syndrome

Williams syndrome is characterised by supravalvar aortic stenosis, elfin facies and hypercalcemia. Learning disability is often associated. Peripheral pulmonary stenosis is also an association. In supravalvar aortic stenosis, the right upper limb blood pressure can be more than that in left upper limb (anisopsphygmia) because the jet is directed towards the brachiocephalic artery. This is known as Coanda effect.

Differentiation of supravalvar aortic stenosis from valvar and subvalvular variety

Murmur of subvalvular aortic stenosis is unlikely to radiate to the carotids. Supravalvar aortic stenosis may radiate more to the right carotid. Ejection click is in favour valvular aortic stenosis. Supravalvar aortic stenosis is unlikely to be associated with aortic regurgitation, while it can occur in valvar and subvalvular variety.

Biventricular outflow obstruction in a child

Noonan syndrome can cause biventricular outflow obstruction due to hypertrophic cardiomyopathy and pulmonary stenosis.

Structural heart diseases associated with WPW syndrome

Ebstein’s anomaly, hypertrophic cardiomyopathy, mitral valve prolapse

Causes of dynamic left ventricular outflow tract (LVOT) obstruction

Hypertrophic cardiomyopathy is the most important cause of dynamic LVOT obstruction. In transposition of great arteries (TGA) with intact interventricular septum LVOT obstruction due to systolic anterior motion of mitral valve (SAM) is possible. SAM can also occur transiently following surgery for aortic stenosis and mitral valve repair and cause LVOT obstruction. Dynamic LVOT obstruction is also described as a rare association with myocardial infarction possibly due to SAM. Dobutamine can worsen the LVOT obstruction in this situation.