Murmurs of 1-2/6 are usually of no clinical importance. LEFT side systolic: Mitral regurgitation Mitral regurgitation (MR) usually results in a holosystolic plateau type murmur over the mitral valve area, radiating dorsally with an intensity varying between 1/6 and 5/6. Up to 60% of normal horses present an ejection-type murmur. Typically, this soft murmur has a crescendo-decrescendo shape, occurs in early to mid-systole, and ends before the onset of the second heart sound. The intensity often varies with slightly changing heart rates. flow murmur (physiological murmur) During systole a large volume of blood is ejected into the great arteries which might be associated with a systolic (functional) flow murmur degree 1-3/6, best heard over the aortic valve area. SYSTOLIC MURMURS LEFT side systolic: Ejection murmur or. The most important cardiac murmurs are listed below. Pathological murmurs are caused by a pathological condition such as valvular regurgitation or congenital cardiac disease. LEFT side systolic: Ejection murmur or flow murmur (physiological murmur) During systole a large volume of blood is ejected into the great arteries which might be associated with a systolic (functional) flow murmur degree 1-3/6, best heard over the Physiological murmurs (or functional murmurs or flow murmurs) result from turbulent flow associated with normal blood flow at high velocity. A right-sided systolic murmur is caused by tricuspid regurgitation or, if the murmur is loud, harsh and located slightly below the tricuspid valve area, by a ventricular septal defect. Thus, in general, a left-sided systolic murmur is caused by mitral regurgitation or by the normal ejection of blood into the great arteries. Systolic murmurs During systole, the mitral valve and tricuspid valve should be closed and blood is ejected into the great arteries. Murmurs that obscure the normal heart sounds (pansystolic or pandiastolic) are more severe that those that do not obscure heart sounds (holosystolic or holodiastolic) The radiation and character are also related to the significance of the murmur. The duration is described as early, mid, late, holo-or pansystolic or –diastolic. The timing of the murmur, such as systolic (between S1 and S2), diastolic (between S2 and S1) or continuous, and the point of maximal intensity already allow to determine the origin of the murmur. However, this is not always the case, especially not for a ventricular septal defect, for a musical murmur or when heart failure is present. The intensity of the murmur is often related to the severity of the regurgitation with louder murmurs being more severe. We therefore need to classify murmurs based upon their timing (systolic or diastolic) and duration, location and radiation, intensity (1 to 6 scale) and character. When a murmur is diagnosed, we first need to identify the source of the murmur and then assess its significance.
Physiological murmurs or functional murmurs result from turbulent flow associated with normal blood flows at high velocity. Murmurs arise when blood flow becomes turbulent, causing vibration of cardiovascular structures.