A healthy volunteer performs a sustained Valsalva maneuver (40 mmHg for 15 seconds) while beat-to-beat arterial pressure is recorded. In normal subjects, the characteristic finding immediately after release of the strain is:
- A A fall in arterial pressure below baseline lasting several seconds
- B A return of arterial pressure directly to baseline with no change in heart rate
- C An overshoot of arterial pressure above baseline followed by reflex bradycardia ✓
- D A progressive rise in arterial pressure without any heart rate change
Correct answer: C. An overshoot of arterial pressure above baseline followed by reflex bradycardia
Explanation
During strain, reduced venous return lowers stroke volume and pressure, provoking tachycardia and vasoconstriction. On release, venous return and cardiac output rebound abruptly while sympathetic vasoconstrictor tone is still active, so arterial pressure overshoots baseline. The raised pressure then unloads baroreceptors less than before, producing reflex bradycardia. Failure of this overshoot and heart rate response defines autonomic failure, which makes the other options wrong.
Reference: Ganong's Review of Medical Physiology, 26th ed.
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