Introduction: The cardiac cycle and cardiac output are core concepts in cardiovascular physiology and pharmacology for B. Pharm students. Understanding phases of the cardiac cycle, pressure–volume relationships, stroke volume, heart rate, ejection fraction, and determinants like preload, afterload and contractility is essential for linking drug actions (inotropes, chronotropes, vasodilators) to clinical effects. Mastery of measurement methods (Fick principle, thermodilution), ECG correlations, and the Frank–Starling mechanism helps predict therapeutic responses and adverse events. These MCQs emphasize mechanism, calculations, pharmacological influence, and clinical interpretation to deepen conceptual understanding. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which equation correctly defines cardiac output?
- Stroke volume × heart rate
- Mean arterial pressure × systemic vascular resistance
- Stroke volume ÷ ejection fraction
- End-diastolic volume − end-systolic volume
Correct Answer: Stroke volume × heart rate
Q2. Which phase of the cardiac cycle corresponds to isovolumetric contraction?
- After ventricular ejection and before atrial contraction
- Between mitral valve opening and atrial systole
- Immediately after mitral valve closure and before aortic valve opening
- During passive ventricular filling
Correct Answer: Immediately after mitral valve closure and before aortic valve opening
Q3. The Frank–Starling law describes the relationship between:
- Afterload and myocardial oxygen consumption
- Preload and stroke volume
- Heart rate and coronary perfusion
- Contractility and systemic vascular resistance
Correct Answer: Preload and stroke volume
Q4. Which change will increase stroke volume acutely?
- Decreased preload
- Increased afterload
- Increased contractility
- Marked bradycardia
Correct Answer: Increased contractility
Q5. Ejection fraction (EF) is calculated as:
- End-diastolic volume ÷ end-systolic volume
- Stroke volume ÷ end-diastolic volume
- Heart rate × stroke volume
- End-systolic volume − end-diastolic volume
Correct Answer: Stroke volume ÷ end-diastolic volume
Q6. Which statement about afterload is true?
- It is primarily determined by venous return
- It is the pressure the ventricle must overcome to eject blood
- Lower afterload reduces myocardial oxygen demand
- Afterload is synonymous with preload
Correct Answer: It is the pressure the ventricle must overcome to eject blood
Q7. On a pressure–volume loop, an increase in contractility shifts which limb?
- Rightward shift of diastolic filling curve
- Upward shift of end-systolic pressure–volume relationship (ESPVR)
- Downward shift of end-diastolic pressure–volume relationship (EDPVR)
- Leftward shift of isovolumetric relaxation line
Correct Answer: Upward shift of end-systolic pressure–volume relationship (ESPVR)
Q8. Which pharmacologic agent primarily increases heart rate (positive chronotropy)?
- Propranolol
- Atropine
- Verapamil
- Digoxin (low dose)
Correct Answer: Atropine
Q9. The Fick principle for cardiac output measurement requires measurement of:
- Aortic pressure and venous pressure
- Oxygen consumption and arteriovenous oxygen difference
- ECG and arterial waveform
- Stroke volume and ejection fraction
Correct Answer: Oxygen consumption and arteriovenous oxygen difference
Q10. Which ECG wave corresponds to ventricular depolarization and precedes ventricular systole?
- P wave
- QRS complex
- T wave
- U wave
Correct Answer: QRS complex
Q11. Thermodilution method for measuring cardiac output uses which principle?
- Indicator dilution using a cold bolus and temperature change downstream
- Oxygen uptake across the lungs
- Continuous arterial pressure integration
- Ultrasound Doppler velocity measurement
Correct Answer: Indicator dilution using a cold bolus and temperature change downstream
Q12. Which condition decreases ejection fraction?
- Hyperdynamic circulation (fever)
- Systolic heart failure with reduced contractility
- Increased sympathetic stimulation
- Administration of positive inotropes
Correct Answer: Systolic heart failure with reduced contractility
Q13. Which factor primarily increases venous return?
- Increased systemic vascular resistance
- Increased intrathoracic pressure
- Skeletal muscle pump during exercise
- Beta-blocker administration
Correct Answer: Skeletal muscle pump during exercise
Q14. Isovolumetric relaxation occurs during which interval?
- Between aortic valve opening and closure
- Immediately after aortic valve closure and before mitral valve opening
- During rapid ventricular filling
- During atrial systole only
Correct Answer: Immediately after aortic valve closure and before mitral valve opening
Q15. Which change would most likely reduce cardiac output?
- Mild anemia
- Acute hemorrhage causing reduced preload
- Thyrotoxicosis
- Administration of a peripheral vasodilator in low doses
Correct Answer: Acute hemorrhage causing reduced preload
Q16. Which statement about stroke volume is correct?
- It equals end-systolic volume minus end-diastolic volume
- It is unaffected by heart rate
- It equals end-diastolic volume minus end-systolic volume
- It is always equal to cardiac output
Correct Answer: It equals end-diastolic volume minus end-systolic volume
Q17. Beta-1 adrenergic stimulation affects the heart by:
- Reducing contractility and decreasing heart rate
- Increasing contractility and increasing heart rate
- Increasing afterload directly
- Causing peripheral vasodilation primarily
Correct Answer: Increasing contractility and increasing heart rate
Q18. Which value represents a normal resting cardiac output in an average adult?
- 2–3 L/min
- 4–8 L/min
- 10–12 L/min
- 15–20 L/min
Correct Answer: 4–8 L/min
Q19. In cardiogenic shock, primary abnormality is:
- Excessive vasodilation with high cardiac output
- Reduced cardiac output due to pump failure
- Hypovolemia from hemorrhage
- Septic vasodilation causing low SVR
Correct Answer: Reduced cardiac output due to pump failure
Q20. Which parameter increases myocardial oxygen demand most directly?
- Decreased heart rate
- Decreased afterload
- Increased contractility and heart rate
- Improved coronary perfusion only
Correct Answer: Increased contractility and heart rate
Q21. Which drug decreases afterload and can increase cardiac output in heart failure?
- Hydralazine
- Propranolol
- Digoxin (high dose)
- Phenylephrine
Correct Answer: Hydralazine
Q22. The rapid ejection phase of systole is characterized by:
- Slow rise in aortic pressure and minimal flow
- Peak ventricular pressure with rapid blood ejection into the aorta
- Closure of the mitral valve
- Isovolumetric relaxation
Correct Answer: Peak ventricular pressure with rapid blood ejection into the aorta
Q23. Which is true about preload?
- Preload is best approximated by end-systolic volume
- Increased preload always decreases stroke volume
- Preload reflects ventricular wall stress at end-diastole and is approximated by end-diastolic volume
- Preload equals systemic vascular resistance
Correct Answer: Preload reflects ventricular wall stress at end-diastole and is approximated by end-diastolic volume
Q24. Which physiological change shortens ventricular filling time and may reduce stroke volume?
- Bradycardia
- Increased venous return
- Tachycardia
- Increased contractility
Correct Answer: Tachycardia
Q25. Which statement about the relationship between mean arterial pressure (MAP), cardiac output (CO), and systemic vascular resistance (SVR) is correct?
- MAP = CO × SVR
- CO = MAP × SVR
- SVR = MAP × CO
- MAP = CO ÷ SVR
Correct Answer: MAP = CO × SVR
Q26. Which valve action produces the first heart sound (S1)?
- Aortic valve closure
- Pulmonic valve closure
- Mitral and tricuspid valve closure
- Mitral valve opening
Correct Answer: Mitral and tricuspid valve closure
Q27. Which clinical intervention would increase preload?
- Administration of a loop diuretic
- Intravenous fluid bolus (crystalloid)
- Administration of a venodilator
- Beta-blocker infusion
Correct Answer: Intravenous fluid bolus (crystalloid)
Q28. In left ventricular failure, pulmonary edema results primarily from:
- Increased systemic arterial pressure
- Elevated pulmonary capillary hydrostatic pressure due to increased left atrial pressure
- Reduced permeability of pulmonary capillaries
- Decreased pulmonary venous return
Correct Answer: Elevated pulmonary capillary hydrostatic pressure due to increased left atrial pressure
Q29. Which measurement directly assesses left ventricular function at the bedside?
- Serum troponin level
- Echocardiographic measurement of ejection fraction
- Chest X-ray cardiothoracic ratio
- Peripheral capillary refill time
Correct Answer: Echocardiographic measurement of ejection fraction
Q30. Digitalis (digoxin) primarily increases cardiac output in heart failure by:
- Blocking beta-1 receptors
- Inhibiting Na+/K+-ATPase to increase intracellular Ca2+ and contractility
- Causing vasodilation via nitric oxide release
- Increasing heart rate via vagal inhibition
Correct Answer: Inhibiting Na+/K+-ATPase to increase intracellular Ca2+ and contractility
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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