Systolic heart murmurs are

heart murmurs Heart murmurs are unique heart sounds produced when blood flows across a heart valve or blood vessel. This occurs when turbulent blood flow creates a sound loud enough to hear with a stethoscope. Turbulent blood flow is not smooth. The sound di ...

heard during

systole Systole ( ) is the part of the cardiac cycle during which some chambers of the heart contract after refilling with blood. The term originates, via New Latin, from Ancient Greek (''sustolē''), from (''sustéllein'' 'to contract'; from ...

, i.e. they begin and end between S1 and S2. Many involve stenosis of the

semilunar valves A heart valve is a one-way valve that allows blood to flow in one direction through the chambers of the heart. Four valves are usually present in a mammalian heart and together they determine the pathway of blood flow through the heart. A heart v ...

or regurgitation of the

atrioventricular valves A heart valve is a one-way valve that allows blood to flow in one direction through the chambers of the heart. Four valves are usually present in a mammalian heart and together they determine the pathway of blood flow through the heart. A heart v ...

Types

* Mid-systolic ejection murmurs are due to blood flow through the

. They occur at the start of blood ejection — which starts after S1 — and ends with the cessation of the blood flow — which is before S2. Therefore, the onset of a midsystolic ejection murmur is separated from S1 by the isovolumic contraction phase; the cessation of the murmur and the S2 interval is the aortic or pulmonary hangout time. The resultant configuration of this murmur is a crescendo-decrescendo murmur. Causes of midsystolic ejection murmurs include outflow obstruction, increased flow through normal semilunar valves, dilation of aortic root or pulmonary trunk, or structural changes in the semilunar valves without obstruction. * Late systolic murmurs start after S1 and, if left sided, extend up to S2, usually in a crescendo manner. Causes include mitral valve prolapse, tricuspid valve prolapse and

papillary muscle The papillary muscles are muscles located in the ventricles of the heart. They attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae and contract to prevent inversion or pro ...

dysfunction. * Holosystolic (pansystolic) murmurs start at S1 and extend up to S2. They are usually due to regurgitation in cases such as mitral regurgitation, tricuspid regurgitation, or ventricular septal defect (VSD).

Types

Individual murmurs

Mid-systolic ejection

Late systolic

Holosystolic (pansystolic)

References