Cardiac Cycle Pressure Equalization

Steps:

• Identify key pressure curves for left atrium, ventricle, and aorta from the diagram.
• Locate the point where ventricular pressure drops below atrial pressure at the end of a specific phase.
• Match this to periods like systole, diastole, or relaxation in the cardiac cycle.
• Confirm the period ends with AV valve opening.

Why A is correct:

• Atrial systole ends when ventricular pressure equals atrial pressure, allowing blood flow (per cardiac cycle physiology).

Why the others are wrong:

• B: Ventricular systole ends with aortic valve closure, not AV opening.
• C: Isovolumetric contraction ends with aortic valve opening, pressures still rising.
• D: Diastole overall ends with atrial systole start, not pressure drop.

Not enough information on exact diagram details, but based on standard left heart pressures.

Final answer: A