Nitroglycerin reduces preload of which chambers? (alternate phrasing)

Nitroglycerin reduces preload of which chambers? (alternate phrasing)

• A. Left atrial and right atrial
• B. Left ventricle only
• C. Right ventricle only
• D. Left ventricular and right ventricular

Answer: (D)

Preload is the ventricular filling pressure (end-diastolic pressure/volume) just before contraction. Nitroglycerin primarily causes venous dilation, which reduces the amount of blood returning to the heart. That drop in venous return lowers the end-diastolic volume and pressure in both ventricles, so both the right and left ventricles experience reduced preload. The question targets ventricular preload, not atrial filling, and the effect is not limited to one ventricle, hence both ventricles are affected.

Preload is the ventricular filling pressure (end-diastolic pressure/volume) just before contraction. Nitroglycerin primarily causes venous dilation, which reduces the amount of blood returning to the heart. That drop in venous return lowers the end-diastolic volume and pressure in both ventricles, so both the right and left ventricles experience reduced preload. The question targets ventricular preload, not atrial filling, and the effect is not limited to one ventricle, hence both ventricles are affected.