Cardiac Anatomy and Physiology
Core anatomy
Know the four chambers, their trabeculated versus smooth components, and the fibrous skeleton that electrically isolates atria from ventricles except at the AV node. Trace the conduction pathway: SA node → internodal/atrial spread → AV node (delay) → bundle of His → right and left bundle branches → Purkinje fibers. Understand the coronary supply: left main divides into LAD (anterior septum, anterior wall) and circumflex (lateral, often posterior in left-dominant systems); RCA supplies the right ventricle and, in most people, the inferior wall and AV node.
Physiology to own
Link the cardiac cycle to what you see on echo: isovolumetric contraction (all valves closed), rapid and slow ejection, isovolumetric relaxation, then diastolic filling with E and A waves. Relate pressure–volume loops to preload, afterload, contractility, and ejection fraction. Understand Frank–Starling as length-dependent force and remember that EF is load-dependent.
Traps
Questions love confusing the moderator band (right ventricle) with a left-ventricular structure, or asking which valve is most anterior (the pulmonary valve sits anterior and superior to the aortic valve). Another trap: describing the mitral valve as tricuspid, or misplacing the coronary sinus (it drains into the right atrium near the IVC). Watch for EF questions where a normal EF coexists with diastolic dysfunction.
Rule of thumb
If a stem describes an inferior infarct with bradycardia, think RCA and AV-node supply; if it describes an anterior infarct with apical dysfunction, think LAD.
Worked example
A patient has an inferior MI and new complete heart block. The RCA supplies the AV node in most hearts, so the conduction disturbance fits an RCA territory event-answer accordingly rather than invoking the LAD.