Cardiac output MCQs With Answer are essential study tools for B. Pharm students preparing for exams in cardiovascular physiology and pharmacology. This concise, Student-friendly post covers cardiac output fundamentals, determinants like heart rate, stroke volume, preload, afterload and contractility, and clinical measurement methods used in practice. Targeted MCQs with answers reinforce understanding of normal values, pathophysiology (heart failure, shock, tamponade), drug effects (inotropes, beta-blockers, vasodilators) and calculation methods. Ideal for revision, these questions bridge cardiac physiology and therapeutic implications to sharpen clinical reasoning. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the formula for cardiac output?
- Cardiac output = Stroke volume × Heart rate
- Cardiac output = Stroke volume ÷ Heart rate
- Cardiac output = Ejection fraction × Heart rate
- Cardiac output = Systemic vascular resistance × Heart rate
Correct Answer: Cardiac output = Stroke volume × Heart rate
Q2. What is the approximate normal resting cardiac output in an average adult?
- 0.5 L/min
- 2 L/min
- 5 L/min
- 10 L/min
Correct Answer: 5 L/min
Q3. Which units are typically used for cardiac output?
- mL/beat
- L/min
- mmHg·min
- L/m²
Correct Answer: L/min
Q4. Stroke volume is defined as:
- The volume of blood ejected per heartbeat from the ventricle
- The volume of blood in the ventricle at end-diastole
- The fraction of blood ejected from the ventricle
- The pressure generated during systole
Correct Answer: The volume of blood ejected per heartbeat from the ventricle
Q5. Which value is a typical normal stroke volume in a healthy adult?
- 10–20 mL
- 40–50 mL
- 60–100 mL
- 150–200 mL
Correct Answer: 60–100 mL
Q6. Ejection fraction (EF) is best described as:
- End-diastolic volume minus end-systolic volume
- Stroke volume divided by end-diastolic volume
- Cardiac output divided by heart rate
- Systemic vascular resistance divided by heart rate
Correct Answer: Stroke volume divided by end-diastolic volume
Q7. Which factor primarily increases stroke volume via the Frank–Starling mechanism?
- Reduced contractility
- Increased preload (end-diastolic volume)
- Increased afterload
- High systemic vascular resistance
Correct Answer: Increased preload (end-diastolic volume)
Q8. Increased afterload (e.g., hypertension) typically has what immediate effect on stroke volume?
- Increases stroke volume
- Decreases stroke volume
- No change in stroke volume
- Converts stroke volume to cardiac index
Correct Answer: Decreases stroke volume
Q9. Which of the following increases cardiac contractility (positive inotropy)?
- Beta-1 adrenergic stimulation
- Acetylcholine acting on muscarinic receptors
- Calcium channel blockade (verapamil)
- Severe acidosis
Correct Answer: Beta-1 adrenergic stimulation
Q10. The Frank–Starling law explains:
- How heart rate determines oxygen consumption only
- The relationship between ventricular preload and stroke volume
- The effect of afterload on venous return
- Baroreceptor sensitivity to blood pressure
Correct Answer: The relationship between ventricular preload and stroke volume
Q11. Sympathetic stimulation affects cardiac output mainly by:
- Decreasing heart rate and contractility
- Increasing heart rate and contractility
- Increasing systemic vascular resistance only
- Lowering preload exclusively
Correct Answer: Increasing heart rate and contractility
Q12. Parasympathetic (vagal) stimulation reduces cardiac output largely by:
- Increasing stroke volume dramatically
- Decreasing heart rate (negative chronotropy)
- Causing systemic vasoconstriction
- Enhancing contractility directly
Correct Answer: Decreasing heart rate (negative chronotropy)
Q13. Which drug class primarily reduces cardiac output by lowering heart rate and contractility?
- Beta-blockers
- ACE inhibitors
- Loop diuretics
- Vasopressors
Correct Answer: Beta-blockers
Q14. Which agent is a commonly used positive inotrope to increase cardiac output in acute heart failure?
- Metoprolol
- Furosemide
- Dobutamine
- Lisinopril
Correct Answer: Dobutamine
Q15. The Fick principle for measuring cardiac output requires measurement of:
- Stroke volume and heart rate only
- Oxygen consumption and arteriovenous oxygen difference
- Systemic vascular resistance and mean arterial pressure
- Left ventricular ejection fraction
Correct Answer: Oxygen consumption and arteriovenous oxygen difference
Q16. Thermodilution measurement of cardiac output is performed using:
- A cuff-based blood pressure monitor
- Temperature change after injectate in pulmonary artery catheter
- Echocardiographic measurement of LV volumes
- Direct Fick oxygen sampling only
Correct Answer: Temperature change after injectate in pulmonary artery catheter
Q17. Mixed venous oxygen saturation (SvO2) decreases when cardiac output:
- Increases, because tissues extract less oxygen
- Decreases, because tissues extract more oxygen
- Is unchanged regardless of CO
- Is equal to arterial oxygen saturation
Correct Answer: Decreases, because tissues extract more oxygen
Q18. Cardiac index is defined as cardiac output divided by:
- Heart rate
- Body surface area (BSA)
- Stroke volume
- Mean arterial pressure
Correct Answer: Body surface area (BSA)
Q19. A normal cardiac index is approximately:
- 0.5–1.0 L/min/m²
- 2.5–4.0 L/min/m²
- 6–8 L/min/m²
- 10–12 L/min/m²
Correct Answer: 2.5–4.0 L/min/m²
Q20. Pulmonary capillary wedge pressure (PCWP) approximates which cardiac parameter?
- Right atrial pressure
- Left ventricular end-diastolic pressure (preload)
- Systemic vascular resistance
- Pulmonary vascular resistance
Correct Answer: Left ventricular end-diastolic pressure (preload)
Q21. Systemic vascular resistance (SVR) primarily affects cardiac output by changing:
- Preload only
- Afterload against which the left ventricle ejects
- Heart rate directly
- Blood oxygen content
Correct Answer: Afterload against which the left ventricle ejects
Q22. Very high heart rates can reduce cardiac output because:
- They always increase stroke volume too much
- They reduce diastolic filling time and stroke volume
- They increase preload significantly
- They increase systemic vascular resistance only
Correct Answer: They reduce diastolic filling time and stroke volume
Q23. Central venous pressure (CVP) is most useful as an estimate of:
- Left ventricular preload
- Right atrial pressure and right ventricular preload
- Systemic vascular resistance
- Left ventricular ejection fraction
Correct Answer: Right atrial pressure and right ventricular preload
Q24. A reduced ejection fraction (<40%) is characteristic of:
- Diastolic heart failure
- Systolic heart failure
- Normal cardiac function
- Pulmonary embolism only
Correct Answer: Systolic heart failure
Q25. Which statement best describes heart failure with preserved ejection fraction (HFpEF)?
- EF is reduced but stroke volume is normal
- EF is preserved; diastolic dysfunction impairs filling and cardiac output
- Only right heart failure is present
- It is exclusively caused by valvular regurgitation
Correct Answer: EF is preserved; diastolic dysfunction impairs filling and cardiac output
Q26. ACE inhibitors can increase cardiac output in heart failure mainly by:
- Increasing afterload
- Reducing afterload and preload via vasodilation
- Blocking beta-1 receptors
- Directly increasing heart rate
Correct Answer: Reducing afterload and preload via vasodilation
Q27. Cardiac tamponade reduces cardiac output primarily by:
- Increasing contractility
- Restricting ventricular filling and reducing preload
- Lowering heart rate dramatically
- Decreasing systemic vascular resistance only
Correct Answer: Restricting ventricular filling and reducing preload
Q28. Dehydration typically affects cardiac output by:
- Increasing preload and CO
- Decreasing preload and CO
- Increasing afterload only
- Raising ejection fraction to supranormal values
Correct Answer: Decreasing preload and CO
Q29. The Fick equation relates oxygen consumption (VO2) to cardiac output and:
- Arterial oxygen content only
- Arteriovenous oxygen content difference (CaO2 − CvO2)
- Systemic vascular resistance
- Ejection fraction
Correct Answer: Arteriovenous oxygen content difference (CaO2 − CvO2)
Q30. Stroke volume can be calculated as:
- End-systolic volume − End-diastolic volume
- End-diastolic volume − End-systolic volume
- Cardiac output × Heart rate
- Heart rate ÷ Cardiac output
Correct Answer: End-diastolic volume − End-systolic volume
Q31. Pulse pressure (systolic − diastolic) is influenced by:
- Only heart rate
- Stroke volume and arterial compliance
- Mixed venous O2 saturation only
- Pulmonary capillary wedge pressure exclusively
Correct Answer: Stroke volume and arterial compliance
Q32. A commonly used invasive index of contractility is:
- dP/dt (rate of pressure rise in ventricle)
- Pulmonary capillary wedge pressure
- Mixed venous oxygen saturation
- Systemic vascular resistance
Correct Answer: dP/dt (rate of pressure rise in ventricle)
Q33. Lusitropy refers to which cardiac property?
- Contraction strength
- Electrical conduction speed
- Myocardial relaxation during diastole
- Valve closure timing
Correct Answer: Myocardial relaxation during diastole
Q34. A drop in arterial blood pressure triggers the baroreceptor reflex to:
- Decrease sympathetic outflow and lower heart rate
- Increase sympathetic outflow to raise heart rate and contractility
- Increase parasympathetic activity only
- Eliminate venous return
Correct Answer: Increase sympathetic outflow to raise heart rate and contractility
Q35. Systemic vascular resistance (SVR) is also commonly called:
- Pulmonary vascular resistance
- Afterload index
- Peripheral vascular resistance
- Venous return
Correct Answer: Peripheral vascular resistance
Q36. Afterload on the left ventricle is most closely related to:
- Diastolic filling time only
- Systolic wall stress and arterial pressure
- Right atrial pressure
- Mixed venous oxygen saturation
Correct Answer: Systolic wall stress and arterial pressure
Q37. In cardiogenic shock, the primary therapeutic goal is to:
- Decrease contractility further
- Increase cardiac output with inotropes and support
- Induce systemic vasodilation exclusively
- Lower heart rate to below 30 bpm
Correct Answer: Increase cardiac output with inotropes and support
Q38. Nitroglycerin primarily improves cardiac output in ischemic heart disease by:
- Increasing preload through venoconstriction
- Decreasing preload via venodilation and reducing myocardial oxygen demand
- Raising heart rate markedly
- Blocking beta-adrenergic receptors
Correct Answer: Decreasing preload via venodilation and reducing myocardial oxygen demand
Q39. Many general anesthetics reduce cardiac output mainly through:
- Increasing sympathetic tone
- Depressing myocardial contractility and reducing systemic vascular resistance
- Increasing preload dramatically
- Raising heart rate substantially
Correct Answer: Depressing myocardial contractility and reducing systemic vascular resistance
Q40. Increasing myocardial contractility will usually have what effect on ejection fraction?
- Decrease EF
- No change in EF
- Increase EF
- Convert EF to stroke volume
Correct Answer: Increase EF
Q41. Atrial fibrillation may reduce cardiac output because:
- It increases effective atrial contraction
- Loss of atrial kick reduces ventricular filling and stroke volume
- It always increases stroke volume by shortening diastole
- It enhances Frank–Starling effect
Correct Answer: Loss of atrial kick reduces ventricular filling and stroke volume
Q42. Echocardiographic measurement of cardiac output commonly uses the LVOT diameter and:
- Mitral inflow velocity only
- Velocity Time Integral (VTI) across LVOT
- Systemic vascular resistance value
- Mixed venous oxygen saturation
Correct Answer: Velocity Time Integral (VTI) across LVOT
Q43. At steady state, cardiac output equals:
- Systemic vascular resistance
- Venous return
- Ejection fraction multiplied by heart rate
- Pulmonary capillary wedge pressure
Correct Answer: Venous return
Q44. Which type of shock is typically associated with a high cardiac output in early stages?
- Hypovolemic shock
- Cardiogenic shock
- Distributive (septic) shock
- Obstructive shock
Correct Answer: Distributive (septic) shock
Q45. Dobutamine acts primarily as a positive inotrope by stimulating:
- Alpha-1 receptors only
- Beta-1 adrenergic receptors
- Muscarinic receptors
- ACE receptor sites
Correct Answer: Beta-1 adrenergic receptors
Q46. Chronic beta-blocker therapy in heart failure benefits patients by:
- Immediately increasing cardiac output on first dose
- Reducing mortality long-term though may acutely lower CO
- Raising systemic vascular resistance indefinitely
- Directly increasing stroke volume by increasing contractility
Correct Answer: Reducing mortality long-term though may acutely lower CO
Q47. Normal pulmonary capillary wedge pressure (PCWP) is approximately:
- 0–2 mmHg
- 4–12 mmHg
- 20–30 mmHg
- 40–50 mmHg
Correct Answer: 4–12 mmHg
Q48. Normal mixed venous oxygen saturation (SvO2) is roughly:
- 20–30%
- 40–50%
- 65–75%
- 90–100%
Correct Answer: 65–75%
Q49. During moderate exercise, cardiac output increases mainly because:
- Heart rate increases and stroke volume increases
- Stroke volume decreases while heart rate falls
- Systemic vascular resistance increases dramatically
- Mixed venous oxygen saturation rises to 100%
Correct Answer: Heart rate increases and stroke volume increases
Q50. Calculate cardiac output: If heart rate = 80 bpm and stroke volume = 70 mL, what is cardiac output?
- 0.56 L/min
- 5.6 L/min
- 560 L/min
- 0.14 L/min
Correct Answer: 5.6 L/min
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