What heart sound is suggestive of ventricular septal defect (VSD)?

A holosystolic murmur is indeed the heart sound that is most suggestive of a ventricular septal defect (VSD). This type of murmur occurs throughout the entire systole, meaning it starts at the first heart sound (S1) and continues until the second heart sound (S2). The reason this specific murmur is associated with VSD lies in the hemodynamics of the defect.

In a VSD, there is an abnormal connection between the left and right ventricles due to a defect in the interventricular septum. During systole, when the left ventricle contracts, blood is ejected into both the aorta and through the defect into the right ventricle. This creates a continuous flow of blood from the left ventricle to the right ventricle, resulting in turbulent blood flow that generates a holosystolic murmur typically best heard at the left lower sternal border.

Other heart sounds, such as a diastolic murmur, a systolic ejection click, or a pericardial friction rub, are not characteristic of VSD. A diastolic murmur is associated with conditions affecting the aortic or mitral valves, while a systolic