| 释义 |
fourth heart sound fourth heart sound (S4), the sound produced in late diastole in association with ventricular filling due to atrial systole and related to reduced ventricular compliance. It is a low frequency oscillation that may be normal at older ages owing to a physiologic decline in ventricular compliance but is nearly always abnormal at younger ages if it is of high intensity or palpable. It is common in ventricular hypertrophy, particularly with hypertension, and is almost invariable during acute myocardial infarction. Fourth heart sounds may arise from the right or left ventricle or both. Synonym(s): atrial soundfourth heart sound Atrial gallop Cardiology A heart sound which occurs late in the presystolic filling phase of the cardiac cycle and is caused by forceful atrial ejection; the 4th HS is best heard over the apex with the Pt in supine or left semilateral position. Cf Third heart sound. fourth heart sound (S4) (fōrth hahrt sownd) The sound produced in late diastole in association with ventricular filling due to atrial systole and related to reduced ventricular compliance. It may be normal at older ages but is nearly always abnormal at younger ages. It is common in ventricular hypertrophy, particularly with hypertension, and is almost invariable during acute myocardial infarction. Fourth heart sounds may arise from the right or left ventricle or both. |