CCS Cardiac Anatomy & Physiology 3 — Questions and Answers
Question 1: The sinoatrial (SA) node is normally supplied by a branch of which coronary artery in approximately 60% of individuals?
- Left anterior descending artery
- Left circumflex artery
- Right coronary artery (Correct answer)
- Obtuse marginal artery
Correct answer: Right coronary artery
In about 60% of individuals, the SA nodal artery arises from the right coronary artery (RCA).
Question 2: Which phase of the cardiac cycle is associated with the highest myocardial oxygen consumption?
- Isovolumetric relaxation
- Rapid ventricular filling
- Isovolumetric contraction (Correct answer)
- Atrial systole
Correct answer: Isovolumetric contraction
Isovolumetric contraction generates maximum wall tension and consumes the most myocardial oxygen.
Question 3: The P-R interval on an ECG represents conduction through which structures?
- SA node and AV node only
- Atria, AV node, and bundle of His (Correct answer)
- Bundle branches and Purkinje fibers
- Ventricular myocardium
Correct answer: Atria, AV node, and bundle of His
The PR interval reflects atrial depolarization and conduction delay through the AV node and bundle of His.
Question 4: Which papillary muscle is most vulnerable to ischemia following an inferior myocardial infarction?
- Anterior papillary muscle
- Posterior medial papillary muscle (Correct answer)
- Septal papillary muscle
- Both papillary muscles equally
Correct answer: Posterior medial papillary muscle
The posteromedial papillary muscle has a single blood supply (usually from the RCA), making it more susceptible to ischemic rupture.
Question 5: What is the approximate normal cardiac output at rest in a healthy adult?
- 1–2 L/min
- 3–4 L/min
- 5–6 L/min (Correct answer)
- 8–10 L/min
Correct answer: 5–6 L/min
Normal resting cardiac output is approximately 5–6 L/min, representing heart rate multiplied by stroke volume.
Question 6: The tricuspid valve is anchored to the right ventricular wall via:
- Trabeculae carneae
- Papillary muscles and chordae tendineae (Correct answer)
- Moderator band only
- Pectinate muscles
Correct answer: Papillary muscles and chordae tendineae
The tricuspid valve leaflets are tethered by chordae tendineae attached to papillary muscles, preventing leaflet prolapse during systole.
Question 7: During ventricular diastole, coronary artery perfusion pressure is primarily determined by:
- Systolic aortic pressure
- Diastolic aortic pressure minus LVEDP (Correct answer)
- Mean pulmonary artery pressure
- Central venous pressure
Correct answer: Diastolic aortic pressure minus LVEDP
Left coronary perfusion occurs mainly in diastole and is driven by the gradient between diastolic aortic pressure and LVEDP.
CCS Cardiac Anatomy & Physiology 3
The sinoatrial (SA) node is normally supplied by a branch of which coronary artery in approximately 60% of individuals?