The fourth heart sound is a low-pitched sound coincident with late diastolic filling of the ventricle due to atrial contraction. It thus occurs shortly before the first heart sound. Although it is also called the , and its production requires an effective atrial contraction, the fourth heart sound is the result of vibrations generated within the ventricle. Commonly, its presence indicates increased resistance to filling of the left or right ventricle because of a reduction in ventricular wall compliance, and it is accompanied by a disproportionate rise in ventricular end-diastolic pressure. In patients with a fourth heart sound, its palpable correlate is often present: a concomitant brief presystolic outward movement of the chest wall.
第四心音是一种低调声音，与心房收缩导致的心室舒张晚期充盈同时出现。因此，它在第一心音之前不久出现。尽管它也被称为[此处原文缺失相关名称]，并且其产生需要有效的心房收缩，但第四心音是心室内产生的振动的结果。通常，它的出现表明由于心室壁顺应性降低，左心室或右心室的充盈阻力增加，并且它伴随着心室舒张末期压力的不成比例升高。在有第四心音的患者中，通常可以触及与之相关的现象：同时出现的胸壁收缩前期短暂向外运动。
