New Series of Interactive Cardiology MCQs 5

Explanation: Ivabradine specifically binds to and inhibits the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in the SA node, blocking the If current to lower heart rate without affecting contractility.

Explanation: In the developed world, cardiac amyloidosis (both AL and ATTR types) is the leading cause of restrictive cardiomyopathy. Endomyocardial fibrosis is more common in tropical regions.

Explanation: Hypokalemia typically presents on an ECG with ST segment depression, flattening or inversion of T waves, and prominent U waves (creating an apparent prolonged QT, though it is actually the QU interval).

Explanation: Anomalous origin of the Left Main (or LAD) from the right coronary cusp with an interarterial course (between the aorta and pulmonary artery) carries the highest risk of compression and sudden death during exertion.

Explanation: Pulsus parvus (weak, small amplitude) et tardus (delayed peak) is the classic arterial pulse finding in severe, fixed aortic valve stenosis due to delayed and reduced LV emptying.

Explanation: Severe AR jets can impinge on the anterior leaflet of the mitral valve, prematurely closing it and creating a functional mitral stenosis rumble known as the Austin Flint murmur.

Explanation: A relative reduction in GLS of >15% from baseline is an early, highly sensitive marker of subclinical left ventricular dysfunction in patients receiving cardiotoxic chemotherapy, occurring before a drop in LVEF.

Explanation: SGLT2 inhibitors (like Dapagliflozin and Empagliflozin) have shown dramatic reductions in cardiovascular mortality and heart failure hospitalizations in HFrEF patients, even in those without diabetes.

Explanation: This specific morphology is known as “digoxin effect.” It indicates that the patient is taking digoxin, but does not necessarily imply digoxin toxicity (which presents with arrhythmias or AV block).

Explanation: Maternal anti-Ro (SSA) and anti-La (SSB) antibodies (associated with SLE or Sjögren’s syndrome) can cross the placenta and destroy the fetal AV node, causing irreversible congenital heart block.

Explanation: The ‘y’ descent marks the fall in right atrial pressure as the tricuspid valve opens and blood rapidly empties into the right ventricle during early diastole.

Explanation: In cardiac tamponade, early diastolic filling is severely restricted due to external pericardial pressure. This prevents the normal rapid drop in atrial pressure, leading to a blunted or absent ‘y’ descent.

Explanation: In patients with atrial fibrillation (the most common cause of cardioembolic stroke), over 90% of thrombi form in the poorly contractile left atrial appendage.

Explanation: Lutembacher syndrome is a rare combination of a congenital ostium secundum ASD and acquired rheumatic mitral stenosis.

Explanation: Severe aortic stenosis is hemodynamically defined as an aortic valve area ≤ 1.0 cm², a mean transvalvular gradient ≥ 40 mmHg, or a peak velocity ≥ 4.0 m/s.

Explanation: Because diastole lasts approximately twice as long as systole at rest, MAP is calculated as the Diastolic Pressure plus one-third of the Pulse Pressure (SBP – DBP).

Explanation: ARVC is characterized pathologically and on MRI by progressive fibrofatty infiltration of the right ventricular free wall, predisposing the patient to fatal ventricular arrhythmias.

Explanation: The standard definition of orthostatic hypotension is a drop in systolic BP of ≥20 mm Hg or diastolic BP of ≥10 mm Hg within 3 minutes of assuming an upright posture.

Explanation: Due to a significantly increased risk of fatal intracranial hemorrhage, prasugrel is strictly contraindicated in patients with any prior history of TIA or stroke.

Explanation: HCM is most commonly caused by mutations in sarcomere protein genes (like MYH7 and MYBPC3) and is inherited in an autosomal dominant pattern.

Explanation: ST elevation > 1mm in right-sided lead V4R is the most sensitive and specific ECG sign for right ventricular infarction, guiding therapy (volume loading, avoiding nitrates).

Explanation: Idarucizumab (Praxbind) binds specifically and irreversibly to dabigatran, rapidly neutralizing its anticoagulant effect in emergency bleeding situations. Andexanet alfa is for factor Xa inhibitors (apixaban, rivaroxaban).

Explanation: Beta-blockers decrease heart rate (prolonging diastole and filling) and reduce myocardial contractility, which decreases the left ventricular outflow tract gradient and relieves angina and dyspnea.

Explanation: Radiation to the carotids and an absent or paradoxically split S2 (due to rigid, immobile aortic leaflets) are hallmark physical findings of severe aortic stenosis.

Explanation: Carvallo’s sign (or Rivero-Carvallo sign) is the amplification of a right-sided heart murmur, notably tricuspid regurgitation, during inspiration due to increased venous return to the right heart.