Which of the following can cause a false reduction of P1/2?

• A. Significant AI
• B. ASD
• C. Reduced LV compliance
• D. All of the above

Answer: (D)

The main idea is that pressure half-time (P1/2) reflects how quickly the diastolic pressure gradient between the aorta and the ventricle decays. It isn’t determined by aortic regurgitation severity alone; it depends on diastolic runoff and loading conditions that shape how fast that gradient falls. Significant aortic insufficiency provides more regurgitant flow during diastole, accelerating the pressure equalization between the LV and the aorta and shortening P1/2. An ASD changes loading and diastolic pressures by altering the overall circulatory dynamics, which can modify the rate at which the diastolic gradient decays and make P1/2 appear shorter than true AR severity. Reduced LV compliance makes the LV diastolic pressure rise more quickly during diastole, narrowing the gradient with the aorta sooner and shortening P1/2 as well. Because each of these factors can hasten the decay of the diastolic gradient, all of them can cause a false reduction of P1/2.