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Physiology & haemodynamics flashcards

7 high-yield MRCP Part 1 cards from the Intellect Medicos Cardiology course. Try to answer each question before you open it — then study them properly with spaced repetition, which brings each card back just before you would forget it.

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1. In a ventricular muscle action potential, which ion's inward current sustains the plateau (phase 2)?

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   Calcium, entering through L-type calcium channels and balanced by potassium leaving the cell.

   Why? Calcium entering during the plateau triggers further calcium release from the sarcoplasmic reticulum, which drives contraction. The long plateau also keeps the cell refractory, so the ventricle cannot be re-stimulated into a sustained contraction.

2. Coronary dominance is defined by which artery gives rise to the ______. In most people this comes from the right coronary artery.

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   posterior descending artery

   Why? The posterior descending artery (PDA) supplies the inferior septum and inferior left ventricular wall. Right dominance is the commonest pattern, which is why most inferior MIs are caused by right coronary artery (RCA) occlusion.

3. Coronary dominance is defined by which artery gives rise to the posterior descending artery. In most people this comes from the ______.

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   right coronary artery

   Why? The posterior descending artery (PDA) supplies the inferior septum and inferior left ventricular wall. Right dominance is the commonest pattern, which is why most inferior MIs are caused by right coronary artery (RCA) occlusion.

4. Which coronary artery supplies the AV node in most people?

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   The right coronary artery (in about 85%).

   Why? The AV node artery usually arises from the dominant artery near the crux of the heart, which is the RCA in most people. This is why inferior MIs often cause heart block.

5. During the strain phase of the Valsalva manoeuvre, which two murmurs get louder?

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   Hypertrophic obstructive cardiomyopathy (HOCM) and mitral valve prolapse (MVP).

   Why? Straining reduces venous return. A smaller left ventricle worsens outflow obstruction in HOCM and lets the mitral leaflet prolapse earlier in MVP. Almost every other murmur softens.

6. Atrial natriuretic peptide is released in response to atrial ______, whereas BNP comes from the ventricles in response to wall stress.

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   stretch

   Why? Both peptides promote natriuresis, diuresis and vasodilation and suppress the renin–angiotensin–aldosterone system. BNP and NT-proBNP rise with ventricular wall stress, which is why they are used to screen for heart failure.

7. Atrial natriuretic peptide is released in response to atrial stretch, whereas BNP comes from the ______ in response to wall stress.

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   ventricles

   Why? Both peptides promote natriuresis, diuresis and vasodilation and suppress the renin–angiotensin–aldosterone system. BNP and NT-proBNP rise with ventricular wall stress, which is why they are used to screen for heart failure.