What makes s1 and s2

Innocent murmurs are the most common cause of SEM see below. Other causes include stenotic lesions aortic and pulmonary stenosis, coarctation of the aorta, Tetralogy of Fallot TOF or relative pulmonary stenosis due to increased flow from an ASD.

Crescendo decrescendo murmur. Examples: ventricular septal defect VSD , mitral and tricuspid valve regurgitation. Holosystolic murmur. In the latter part of systole, the small VSD may close or become so small to not allow discernible flow through and the murmur is no longer audible.

Decrescendo murmur. Diastolic murmurs are usually abnormal, and may be early, mid or late diastolic. Continuous murmurs are heard during both systole and diastole. They occur when there is a constant shunt between a high and low pressure blood vessel. Examples: patent ductus arteriosus PDA and systemic arterio-venous fistulas. This may also occur in surgically placed shunts such as a Blalock-Tauussig BT shunt between the aorta and the pulmonary artery.

Cardiology Part 2 - EKG. Index of Core Concept Chapters. A bout Core Concepts. The Cardiac Cycle — Left ventricular pressure — Aortic pressure — Left atrial pressure Cardiac cycle of the left side of the heart. More information: Examples of innocent murmurs.

It can be a normal finding in people aged 40 or under. Pathological causes are mostly related to heart failure and include:. S4 heart sound. S4 arises when the atria contract against a stiff ventricle such as in states of ventricular hypertrophy. Causes include:. A rare diastolic heart sound classically associated with the movement of the tumour in atrial myxomas.

Wide-splitting S 2 — splitting increases with inspiration:. Fixed splitting S 2 — splitting not affected by breathing:. Cause: Atrial septal defect. Your email address will not be published. Save my name and email in this browser for the next time I comment. Submit Comment. See more Login to enrol on courses and monitor progress. Ejection systolic click in aortic stenosis and pulmonary stenosis. Mid-systolic click in mitral valve prolapse. Opening snap seen in mitral stenosis and tricuspid stenosis.

Pathological S3 and S4 heart sounds. Wide-splitting of S2. Splitting increases with inspiration. Fixed splitting of S2. Splitting is not affected by inspiration. Reversed splitting of S2. The "lub" is the first heart sound, commonly termed S1, and is caused by turbulence caused by the closure of mitral and tricuspid valves at the start of systole. The second heart sound, "dub" or S2, is caused by the closure of the aortic and pulmonic valves, marking the end of systole.

Thus the time period elapsing between the first heart sound and the second sound defines systole ventricular ejection and the time between the second sound and the following first sound defines diastole ventricular filling.

Please listen to an example of a normal heart sound:. These are the normal heart rate values.