when is the second sound of the heartbeat produced
during inhalation
title: Heart text: of the atrioventricular valves during ventricular contraction and is normally described as "lub". The second heart sound, S2, is the sound of the semilunar valves closing during ventricular diastole and is described as "dub". Each sound consists of two components, reflecting the slight difference in time as the two valves close. S2 may split into two distinct sounds, either as a result of inspiration or different valvular or cardiac problems. Additional heart sounds may also be present and these give rise to gallop rhythms. A third heart sound, S3 usually indicates an increase in ventricular blood volume. A fourth heart title: Heart sounds text: Heart sounds Heart sounds are the noises generated by the beating heart and the resultant flow of blood through it. Specifically, the sounds reflect the turbulence created when the heart valves snap shut. In cardiac auscultation, an examiner may use a stethoscope to listen for these unique and distinct sounds that provide important auditory data regarding the condition of the heart. In healthy adults, there are two normal heart sounds, often described as a "lub" and a "dub" (or "dup"), that occur in sequence with each heartbeat. These are the first heart sound (S) and second heart sound (S), produced title: Cardiac physiology text: during ventricular contraction and is normally described as "lub". The second heart sound, S2, is the sound of the semilunar valves closing during ventricular diastole and is described as "dub". Each sound consists of two components, reflecting the slight difference in time as the two valves close. S2 may split into two distinct sounds, either as a result of inspiration or different valvular or cardiac problems. Additional heart sounds may also be present and these give rise to gallop rhythms. A third heart sound, S3 usually indicates an increase in ventricular blood volume. A fourth heart sound S4 is referred title: Heart sounds text: the ventricles against closed semilunar valves, sends blood rushing back toward the atria, and the parachute-like valves catch the rush of blood in their leaflets causing the valve to snap shut. The S1 sound results from reverberation within the blood associated with the sudden block of flow reversal by the valves. The delay of T1 even more than normally causes the split S1 which is heard in a right bundle branch blockage. The second heart sound, or S, forms the "dub" of "lub-dub" and is composed of components A (aortic valve closure) and P (pulmonary valve closure). Normally A precedes title: Isovolumic relaxation time text: Isovolumic relaxation time Isovolumic relaxation time (IVRT) is an interval in the cardiac cycle, from the aortic component of the second heart sound, that is, closure of the aortic valve, to onset of filling by opening of the mitral valve. It can be used as an indicator of diastolic dysfunction. It can be measured by simultaneous Doppler echocardiography and M-mode sonography, or better still, by simultaneous phonocardiogram and transmitral Doppler. Prolonged IVRT indicates poor myocardial relaxation. A normal IVRT is about 70 ± 12 ms, and approximately 10 ms longer in people over forty years. In abnormal relaxation, IVRT is