CVS Practice Test

The atrial kick refers to the additional volume of blood that the atria push into the ventricles during the final phase of diastole, just before the ventricles contract. This occurs when the atria contract, ensuring that the ventricles are adequately filled with blood before pumping it out to the body. Typically, the contribution of the atrial kick to left ventricular filling is around 20-30%.

The correct answer signifies that approximately 30% of the total left ventricular filling is due to the atrial kick. This emphasizes the importance of atrial contraction in the overall cardiac cycle, particularly in conditions or situations where the heart's ability to fill passively (due to gravity and the pressure from venous return) might be compromised, such as during higher heart rates or certain cardiac pathologies.

Other percentages would suggest a lesser contribution from the atrial kick, which would not fully represent its significant role in cardiac physiology. Therefore, recognizing the atrial kick's true contribution to ventricular filling is essential for understanding heart mechanics and functions.