What percentage of left ventricle filling is typically contributed by atrial systole?

Atrial systole contributes approximately 20% to 30% of left ventricular filling, making the chosen answer of 30% appropriate. During the cardiac cycle, left ventricular filling occurs in three phases, with the primary phase being rapid passive filling during diastole when blood flows from the left atrium to the left ventricle due to pressure differences. Atrial systole follows this passive phase and acts to top off the left ventricle by pushing additional blood into it just before ventricular contraction.

This contribution can vary depending on several factors, including heart rate and overall cardiovascular health. In healthy individuals at rest, the active contraction of the atria adds this crucial volume of blood, enhancing the efficiency of ventricular filling and ensuring adequate preload for optimal cardiac output. In situations such as atrial fibrillation where atrial contraction may be lost, the contribution from atrial systole becomes more significant in understanding the implications for cardiac output and overall heart function.