EDAIC Cardiovascular Physiology and Pharmacology 3 — Questions and Answers
Question 1: In a patient with aortic stenosis, which hemodynamic pattern is expected?
- Low SVR, high CO
- High LVEDP, low transaortic gradient
- High transaortic gradient, concentric LV hypertrophy (Correct answer)
- Low LVEDP, dilated LV
Correct answer: High transaortic gradient, concentric LV hypertrophy
Severe aortic stenosis creates a high pressure gradient across the valve and leads to concentric left ventricular hypertrophy from chronic pressure overload.
Question 2: The coronary perfusion pressure is defined as:
- MAP minus CVP
- Aortic diastolic pressure minus LVEDP (Correct answer)
- Systolic BP minus PCWP
- MAP minus PCWP
Correct answer: Aortic diastolic pressure minus LVEDP
Coronary perfusion pressure = aortic diastolic pressure minus left ventricular end-diastolic pressure, as most LV coronary flow occurs during diastole.
Question 3: Which receptor subtype mediates vasodilation when activated by dopamine at low doses (1-3 mcg/kg/min)?
- Alpha-1 adrenoceptors
- Beta-2 adrenoceptors
- DA1 dopaminergic receptors (Correct answer)
- Beta-1 adrenoceptors
Correct answer: DA1 dopaminergic receptors
At low doses, dopamine activates DA1 receptors in renal and splanchnic vasculature, causing vasodilation and increased renal blood flow.
Question 4: What is the primary mechanism by which volatile anesthetics cause myocardial depression?
- Blocking beta-1 adrenoceptors
- Reducing intracellular calcium availability and sensitization (Correct answer)
- Inhibiting myosin ATPase directly
- Blocking sodium channels in myocytes
Correct answer: Reducing intracellular calcium availability and sensitization
Volatile anesthetics impair calcium release from the sarcoplasmic reticulum and reduce myofilament calcium sensitivity, depressing myocardial contractility.
Question 5: In the pressure-volume loop of the left ventricle, the width of the loop represents:
- Heart rate
- Stroke volume (Correct answer)
- Cardiac output
- Contractility
Correct answer: Stroke volume
The horizontal width of the LV pressure-volume loop represents stroke volume (the difference between end-diastolic and end-systolic volumes).
Question 6: Which of the following best describes the effect of milrinone on cardiac physiology?
- Pure chronotropic effect with no inotropy
- Positive inotropy and vasodilation via PDE3 inhibition (Correct answer)
- Negative inotropy with vasodilation
- Positive inotropy with vasoconstriction
Correct answer: Positive inotropy and vasodilation via PDE3 inhibition
Milrinone inhibits phosphodiesterase III, increasing cAMP, causing positive inotropy in the heart and vasodilation in peripheral vessels (inodilator).
Question 7: Vasopressin (ADH) causes vasoconstriction primarily through which receptor?
- V1 receptors on vascular smooth muscle (Correct answer)
- V2 receptors in the renal collecting duct
- Alpha-1 adrenoceptors
- Angiotensin II type 1 receptors
Correct answer: V1 receptors on vascular smooth muscle
V1 receptors on vascular smooth muscle mediate vasopressin-induced vasoconstriction via the phospholipase C/IP3 pathway and intracellular calcium release.
EDAIC Cardiovascular Physiology and Pharmacology 3
In a patient with aortic stenosis, which hemodynamic pattern is expected?