Atrial contraction and propulsion of blood into a noncompliant ventricle produces which heart sound?

The production of the S4 heart sound is associated with atrial contraction, particularly when blood is being propelled into a noncompliant ventricle. This sound occurs just before the S1 heart sound and is often referred to as an "atrial gallop." It is typically caused by increased resistance to filling during late diastole, which can be the result of conditions such as hypertensive heart disease or left ventricular hypertrophy, where the ventricular walls become stiff and less compliant.

In contrast, the S1 sound is produced by the closure of the atrioventricular (AV) valves at the beginning of systole, while the S3 sound, commonly known as a "ventricular gallop," occurs during early diastole when blood rushes into the ventricles, often indicating heart failure or volume overload. An opening snap is associated with mitral stenosis and occurs after the S2 heart sound due to the abrupt halt of the valve leaflets in their opening. Therefore, the sound related to atrial contraction into a noncompliant ventricle is indeed the S4 heart sound.