CCI Cardiac Pharmacology and Hemodynamic Monitoring 1 — Questions and Answers
Question 1: Which pharmacological agent is used as a vasodilator stressor during pharmacologic stress testing in patients who cannot exercise adequately?
- Dobutamine
- Regadenoson (adenosine A2A agonist) (Correct answer)
- Epinephrine
- Norepinephrine
Correct answer: Regadenoson (adenosine A2A agonist)
Regadenoson (and adenosine) is a vasodilator stressor used in pharmacologic stress testing; it causes coronary vasodilation to unmask flow-limiting stenoses in patients unable to exercise.
Question 2: What is the mechanism of action of dobutamine when used as a pharmacologic stressor in stress echocardiography?
- Coronary vasodilation through adenosine receptor activation
- Beta-1 adrenergic stimulation increasing heart rate and contractility to simulate exercise (Correct answer)
- Alpha-1 receptor blockade causing peripheral vasodilation
- Calcium channel blockade reducing afterload
Correct answer: Beta-1 adrenergic stimulation increasing heart rate and contractility to simulate exercise
Dobutamine primarily stimulates beta-1 receptors, increasing heart rate and myocardial contractility to create demand ischemia similar to exercise.
Question 3: Which hemodynamic parameter is calculated by dividing cardiac output by mean arterial pressure minus central venous pressure?
- Systemic vascular resistance (Correct answer)
- Pulmonary vascular resistance
- Cardiac index
- Stroke volume
Correct answer: Systemic vascular resistance
Systemic vascular resistance (SVR) = (MAP – CVP) / CO × 80, expressed in dynes·sec/cm⁵, reflecting the total resistance the left ventricle must overcome.
Question 4: During a cardiac catheterization, a pulmonary capillary wedge pressure (PCWP) of 22 mmHg indicates which condition?
- Normal left heart filling pressure
- Elevated left atrial pressure suggesting left heart failure or mitral stenosis (Correct answer)
- Right ventricular failure in isolation
- Pericardial effusion without tamponade
Correct answer: Elevated left atrial pressure suggesting left heart failure or mitral stenosis
Normal PCWP is 6–12 mmHg; a PCWP of 22 mmHg indicates elevated left atrial pressure, consistent with left heart failure, volume overload, or mitral stenosis.
Question 5: Which class of antiarrhythmic drugs blocks sodium channels and is classified as Class I according to the Vaughan Williams classification?
- Beta-blockers (e.g., metoprolol)
- Sodium channel blockers (e.g., lidocaine, flecainide) (Correct answer)
- Potassium channel blockers (e.g., amiodarone)
- Calcium channel blockers (e.g., verapamil)
Correct answer: Sodium channel blockers (e.g., lidocaine, flecainide)
Vaughan Williams Class I antiarrhythmics (e.g., lidocaine, flecainide, procainamide) block fast sodium channels, slowing phase 0 depolarization and conduction velocity.
Question 6: What is the primary hemodynamic effect of intravenous nitroglycerin at low doses used in acute heart failure management?
- Arterial vasoconstriction increasing afterload
- Venodilation reducing preload and left ventricular filling pressures (Correct answer)
- Positive inotropic effect increasing contractility
- Chronotropic effect increasing heart rate
Correct answer: Venodilation reducing preload and left ventricular filling pressures
At low IV doses, nitroglycerin primarily causes venodilation, reducing venous return (preload) and decreasing pulmonary congestion and LV filling pressures.
CCI Cardiac Pharmacology and Hemodynamic Monitoring 1
Which pharmacological agent is used as a vasodilator stressor during pharmacologic stress testing in patients who cannot exercise adequately?