A nurse is reviewing the anatomy and physiologic functioning of the heart. The nurse should recognize that which statement best describes the atrial kick?
A.
The atria contract toward the end of diastole and push the remaining blood into the ventricles.
B.
The atria contract during systole and attempt to push against closed valves.
C.
Atrial kick is the pressure exerted against the atria as the ventricles contract during systole.
D.
Contraction of the atria at the beginning of diastole can be felt as a palpitation.
The Correct Answer and Explanation is:
The correct answer is A. “The atria contract toward the end of diastole and push the remaining blood into the ventricles.”
Explanation:
The term “atrial kick” refers to the contraction of the atria that occurs toward the end of diastole (the heart’s relaxation phase), before the ventricles contract. During this phase, the ventricles are passively filled with blood from the atria, but about 20-30% of the blood remains in the atria. To ensure the ventricles are filled adequately, the atria contract to push this remaining blood into the ventricles. This final push of blood into the ventricles is called the atrial kick.
The atrial kick is critical in maintaining proper cardiac output, particularly in conditions where ventricular filling may be compromised, such as in tachycardia or heart failure. It accounts for up to 30% of ventricular filling, and without this contribution, the heart’s efficiency would decrease, leading to inadequate perfusion of tissues and organs. In patients with atrial fibrillation, for instance, the loss of an effective atrial kick can lead to symptoms of heart failure because the ventricles are not optimally filled.
Option B is incorrect because the atria contract during diastole, not systole. Option C is wrong because atrial kick refers to atrial contraction, not pressure exerted by the ventricles during systole. Option D is incorrect since atrial contraction at the start of diastole does not cause palpitations; atrial kick occurs at the end of diastole, and it is not typically felt as a palpitation.
In summary, atrial kick plays a vital role in ensuring efficient ventricular filling, especially during the heart’s diastolic phase, contributing to overall cardiac function and output.