Which statement is false regarding preload, afterload, and ventricular response?

Which statement is false regarding preload, afterload, and ventricular response?

• A. Increased preload shifts the Frank-Starling curve to the right.
• B. Increased afterload reduces stroke volume by steepening ESPVR.
• C. Inspiration increases venous return to the right heart.
• D. The right ventricle is less susceptible to increases in afterload than the left ventricle.

Answer: (D)

The key idea is how preload, afterload, and the ventricle’s structure determine pumping performance. Increasing preload stretches the ventricle more before it contracts, and the length-tension relationship makes the heart contract more forcefully, so stroke volume goes up. Higher afterload means the ventricle must generate more pressure to eject blood; if the pressure is too high, less blood is ejected and stroke volume falls. Inspiration lowers intrathoracic pressure, which draws more blood back to the right heart, increasing venous return and right-side preload. The right ventricle, with its thinner wall and normally low-resistance pulmonary circuit, is more vulnerable to increases in afterload; when pulmonary vascular resistance rises, the RV struggles to eject against that load, and its stroke volume drops. The left ventricle is better equipped to handle higher systemic afterload because it can generate greater pressures. So the statement that the right ventricle is less susceptible to increases in afterload is the false one.

The key idea is how preload, afterload, and the ventricle’s structure determine pumping performance. Increasing preload stretches the ventricle more before it contracts, and the length-tension relationship makes the heart contract more forcefully, so stroke volume goes up. Higher afterload means the ventricle must generate more pressure to eject blood; if the pressure is too high, less blood is ejected and stroke volume falls. Inspiration lowers intrathoracic pressure, which draws more blood back to the right heart, increasing venous return and right-side preload. The right ventricle, with its thinner wall and normally low-resistance pulmonary circuit, is more vulnerable to increases in afterload; when pulmonary vascular resistance rises, the RV struggles to eject against that load, and its stroke volume drops. The left ventricle is better equipped to handle higher systemic afterload because it can generate greater pressures. So the statement that the right ventricle is less susceptible to increases in afterload is the false one.