BCA Cardiovascular Anesthesia 2 — Questions and Answers
Question 1: Which volatile anesthetic best preserves cardiac output in patients with severe left ventricular dysfunction?
- Desflurane
- Isoflurane
- Sevoflurane (Correct answer)
- Halothane
Correct answer: Sevoflurane
Sevoflurane causes less myocardial depression and provides cardioprotection via preconditioning, making it preferred in severe LV dysfunction.
Question 2: A patient on cardiopulmonary bypass develops ST elevation in lead II. The most likely cause is:
- Air embolism to right coronary artery (Correct answer)
- Hypothermia-induced QRS changes
- Inadequate cardioplegia to the RCA territory
- Ventricular fibrillation artifact
Correct answer: Air embolism to right coronary artery
Air entrainment preferentially affects the right coronary artery (most anterior), causing RCA territory ischemia manifesting as inferior ST elevation.
Question 3: The gold standard for assessing myocardial viability in a patient with chronic ischemic cardiomyopathy prior to CABG is:
- Dobutamine stress echocardiography
- Thallium SPECT imaging
- Cardiac MRI with gadolinium
- PET scanning with FDG (Correct answer)
Correct answer: PET scanning with FDG
FDG-PET identifies hibernating myocardium with high sensitivity and specificity, making it the gold standard for viability assessment.
Question 4: During aortic valve replacement, the aortic cross-clamp time is most directly associated with:
- Risk of renal failure
- Degree of myocardial ischemia (Correct answer)
- Incidence of stroke
- Duration of coagulopathy
Correct answer: Degree of myocardial ischemia
Cross-clamp time directly correlates with the duration of global myocardial ischemia despite cardioplegia, affecting postoperative ventricular function.
Question 5: Protamine reversal of heparin can cause pulmonary hypertension via:
- Direct pulmonary vasoconstriction from protamine
- Thromboxane A2 release from pulmonary macrophages (Correct answer)
- Systemic release of histamine causing RV dilation
- Heparin-protamine complexes activating complement
Correct answer: Thromboxane A2 release from pulmonary macrophages
Heparin-protamine complexes activate complement and stimulate pulmonary macrophages to release thromboxane A2, causing severe pulmonary vasoconstriction.
Question 6: Which hemodynamic pattern is characteristic of cardiac tamponade?
- Elevated CVP, low PCWP, low CO
- Equalization of diastolic pressures, low CO (Correct answer)
- Low CVP, elevated PCWP, normal CO
- Elevated SVR with preserved CO
Correct answer: Equalization of diastolic pressures, low CO
Tamponade causes equalization of right atrial, right ventricular diastolic, pulmonary artery diastolic, and pulmonary capillary wedge pressures with reduced cardiac output.
Question 7: In a patient with hypertrophic obstructive cardiomyopathy undergoing noncardiac surgery, which intraoperative event would MOST worsen the outflow tract obstruction?
- Phenylephrine infusion
- Increased preload with fluid bolus
- Tachycardia with hypovolemia (Correct answer)
- Bradycardia with beta-blocker administration
Correct answer: Tachycardia with hypovolemia
Tachycardia decreases diastolic filling time and hypovolemia reduces preload, both worsening LVOT obstruction by allowing the hypertrophied septum to approach the anterior mitral leaflet.
BCA Cardiovascular Anesthesia 2
Which volatile anesthetic best preserves cardiac output in patients with severe left ventricular dysfunction?