Generally the risk of sudden cardiac death in hypertrophic cardiomyopathy is considered to be high in those with a septal thickness of 30 mm or more. Implantation of an ICD (Implantable Cardioverter Defibrillator) may be considered in such situations. Those with a family history of premature sudden death also have a high risk and so do those with a history of resuscitated cardiac arrest. Recurrent episodes of non sustained ventricular tachycardia and syncope are also considered as risk factors.

Acidosis is associated with hyperkalemia due to extracellular shift of potassium. Hypercalcemia shortens the ST segment.

Prominent R waves are seen in anterior leads with right bundle branch block and right ventricular hypertrophy.

Troponin T levels remain elevated for two weeks after a myocardial infarction. Hence it is not useful in diagnosing early re-infarction.

In AVRT, since the atria and ventricles are involved in the re-entrant circuit, atrial rate is always equal to ventricular rate. The tachycardia will not be sustained if there is a block in either limbs of the circuit (aneterograde or retrograde). Atrial tachycardia and flutter can continue in the presence of a block in conduction to the ventricles, though one to one conduction is also possible. Bundle branch re-entry causes ventricular tachycardia, which can have VA dissociation.

In concealed AV bypass tract, it is the anterograde conduction which is absent, making it obscure in sinus rhythm. Retrograde conduction causes AVRT. It is well known that accessory pathway refractory period decreases when the rate increases as in atrial fibrillation and anterograde conduction may occur.

The term step down is used when the given chamber has an oxygen saturation less than that of the proximal chamber. In TGA, aorta is connected to the pulmonary artery and has a lower oxygen saturation. Pulmonary artery is connected to the left ventricle receiving oxygenated blood from the left atrium. Hence when there is a PDA, desaturated blood enters the pulmonary artery from the aorta causing a step down in oxygen saturation compared to left ventricle which is the proximal chamber in this case.

Myocarditis, if at all, should produce a decrease in QRS voltage

Intravenous calcium is given for the treatment of hyperkalemia.

Fungal endocarditis is characterized by large vegetations an is the most difficult to treat among the native valve endocarditis. Prolonged treatment courses and poor results are the rule. Fortunately, it is much rare compared to the other types.

Increased EDV (end diastolic volume) and ESV (end systolic volume) are seen in systolic dysfunction. Ejection fraction (EF) is normal in diastolic dysfunction and decreased in systolic dysfunction. EDP (end diastolic pressure) is elevated in both diastolic and systolic dysfunction. E/A reversal is a feature of diastolic dysfunction, noted on Doppler echocardiography.

The International Classification of adult underweight, overweight and obesity according to BMI (World Health Organization) is as follows:

Underweight <18.50

Normal range 18.50 – 24.99

Overweight ≥25.00
Pre-obese 25.00 – 29.99

Obese ≥30.00
Obese class I: 30.00 – 34.99
Obese class II: 35.00 – 39.99
Obese class III: ≥40.00

QRS widening is a feature of severe hyperkalemia in such a way that QRS complex merges with the T wave to produce the sine wave pattern. Diminished P wave amplitude and atrial paralysis in hyperkalemia leads to sinoventricular conduction.

Abciximab is an intravenous glycoprotein IIb/IIIa blocker which is a monoclonal antibody, useful as an adjunct in percutaneous coronary intervention when there is a thrombus load in the coronary artery. Glycoprotein IIb/IIIa is the receptor in the final common pathway for platelet activation.

Gross enlargement of the cardiac silhouette is unlikely in tetralogy of Fallot as there is no dilatation of the cardiac chambers in this condition, though the right ventricle is hypertrophied. In pericardial effusion and posterior mediastinal tumour, though the cardiac size itself is not enlarged, the shadow on chest x-ray can be large, mimicking cardiomegaly. In Ebstein’s anomaly of the tricuspid valve, a large right atrium along with atrialized portion of the right ventricle produces the enlargement in the cardiac silhouette.

Mycotic aneurysm is seen in infective endocarditis. Oppenheimer EH. The association of adult-type coarctation of the aorta with endocardial fibroelastosis in infancy. Bull Johns Hopkins Hosp. 1953;93:309-19.

Uhl’s anomaly is otherwise known as parchment right ventricle.

Thrombospondins are proteins with antiangiogenic properties. Thrombomodulin is a cofactor in the thrombin-induced activation of protein C which is a natural anticoagulant.

Pulsus paradoxus is an important finding in cardiac tamponade. It can also occur in chronic obstructive pulmonary disease. It is rare in constrictive pericarditis. It may also be rarely observed in pulmonary embolism, marked obesity, pregnancy and partial obstruction of the superior vena cava. On the other hand, in those with aortic regurgitation and atrial septal defect, pulsus paradoxus may not occur even if there is associated cardiac tamponade [Textbook of cardiovascular medicine, by Eric J. Topol, Robert M. Califf. Chapter 16, Page 197]. Reverse pulsus paradoxus (inspiratory rise of arterial pressure) may be noted in hypertrophic cardiomyopathy, intermittent positive pressure ventilation and isorhythmic AV dissociation.

In general, cyanosis becomes apparent when the deoxyhemoglobin content in capillary blood becomes 4-6 gm%. Cyanosis is detectable with methemoglobin levels of 1.5% and sulfhemoglobin levels of 0.5 gm% [Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Walker HK, Hall WD, Hurst JW, editors. Boston: Butterworths; 1990. Chapter 45 Cyanosis: Available at: http://www.ncbi.nlm.nih.gov/books/NBK367/

First inspiration produces a marked decrease in the pulmonary vascular reistance. Loss of the low resistance placental circulation and the gradual closure of the ductus arteriosus increases the systemic vascular resistance. Increase in systemic oxygen saturation due removal of admixture seen in fetal life also contributes to an increase in systemic vascular resistance. Pulmonary and systemic circulations are connected in series. This means that systemic venous drainage is pumped into the pulmonary arterial circulation and the pulmonary venous drainage is pumped into the systemic arterial circulation. Parallel circuit is seen in complete transposition of great arteries where the systemic venous drainage reaches the aorta and pulmonary venous drainage reaches the pulmonary artery. A parallel circuit is incompatible with life unless there is a provision for good mixing at atrial, ventricular or great arterial level (best option is mixing at the atrial level).

Splenomegaly is more common in sub acute infective endocarditis of long duration. Clinical manifestations of endocarditis generally occur within two weeks of the inciting bacteremia in 80% of cases [Braunwald's Heart Diseases, 8th Edition].

Coagulase negative Staphylococcus epidermidis contributed 33% and Staphylococcus aureus contributed 19% of the early prosthetic valve endocarditis (occurring within twelve months) [Braunwald's Heart Diseases, Eight Edition, table on page 1715].

Ventricular septal defect, pulmonary stenosis and complete heart block are common association of corrected transposition of great arteries (cTGA). Since septal activation sequence is inverted due to ventricular inversion, lateral Q waves are not seen and right sided Q waves may be seen.

Since several risk predictors for sudden death are present, it may be better to implant an ICD straight away without going for an EPS.

Cor triatriatum dexter is the partitioning of right atrium into two chambers and will not cause elevation of the pulmonary capillary wedge pressure. Cor triatriatum sinister (or simply cor triatriatum, as it is more common on the left side) is the partitioning of left atrium into two which causes mitral inflow obstruction and elevation of pulmonary capillary wedge pressure.

Tricuspid valve goes with the right ventricle and is attached more distally than the mitral valve. The attachments of the tricuspid leaflets are anterior, posterior and septal. Moderator band contains the right bundle branch.

Patency of radial grafts are better than that of venous grafts, though they are inferior to internal mammary artery grafts. Radial artery grafts are free grafts while the internal mammary artery grafts are live grafts with the proximal end being still connected to the subclavian artery. They have good pulsatile flow and their sizes match well with that of the recipient coronaries.

Aortic disease is a contra indication for introduction of an intra aortic counter pulsation balloon (IABP). Aortic regurgitation makes IABP ineffective as balloon is inflated in diastole and significant aortic regurgitation prevents the function of a balloon pump. In post myocardial infarction ventricular septal defect, IABP enhances the myocardial perfusion and reduces the left ventricular afterload which reduces shunting across the ventricular septal defect.