Arrhythmias can lower cardiac output and cause which of the following problems?

• A. Lower cardiac output and irregular contractions
• B. Increase in stroke volume
• C. No effect on heart rate
• D. Improvement in diastolic filling

Answer: (A)

Arrhythmias disrupt the timing and regularity of heartbeats, which directly affects how well the heart fills and ejects blood, and thus cardiac output. Cardiac output = heart rate × stroke volume, so when rhythm is irregular or too fast, filling time shortens and the atrial kick may be lost, lowering stroke volume and making contractions less coordinated. The choice that describes both reduced cardiac output and irregular contractions fits this pattern, reflecting how arrhythmias impair both the rate and the efficiency of pumping. An increase in stroke volume isn’t typical with arrhythmias because filling is often compromised. Saying there’s no effect on heart rate or that diastolic filling improves also contradicts the common impact of rhythm disturbances on filling time and atrial contribution.