These differ in the part of the heartbeat they make sound, during systole, or diastole. Yet, continuous murmurs create sound throughout both parts of the heartbeat. Continuous murmurs are not placed into the categories of diastolic or systolic murmurs. Diagnostic approach and diagnosis
Classification
Murmurs have seven main characteristics. These include timing, shape, location, radiation, intensity, pitch and quality. Timing refers to whether the murmur is a systolic, diastolic, or continuous murmur. Shape refers to the intensity over time. Murmurs can be crescendo, decrescendo or crescendo-decrescendo. Crescendo murmurs increase in intensity over time. Decrescendo murmurs decrease in intensity over time. Crescendo-decrescendo murmurs have both shapes over time. These have progressive increase in intensity, peak, and progressive decrease in intensity. Crescendo–decrescendo murmurs resemble a diamond or kite shape. Location refers to where the heart murmur is usually heard best. There are four places on the anterior chest wall to listen for heart murmurs. Each location roughly corresponds to a specific part of the heart. Health care providers listen to these areas with a stethoscope.Position for auscultation: The patient is most often lying on their back (supine) with the head of bed at slight upward angle. The head of the bed is usually at a 30 degree upward angle. Usually the health care provider is standing to the right of the person they are examining. Below are positional changes that one may use:
Left lateral decubitus (lying on the left side). This will decrease the distance from wall of the chest to the apex of the heart.
Following this is a parasternal early diastolic and mid-diastolic murmur (Austin Flint murmur). The exact cause of an Austin Flint murmur is unknown. Hypothesis is that the mechanism of murmur is from the severe aortic regurgitation. In severe aortic regurgitation the jet vibrates the anterior mitral valve leaflet. This causes collision with the mitral inflow during diastole. As such, the mitral valve orifice narrows. This results in increased mitral inflow velocity. This leads to the jet impinging on the myocardial wall.Ruptured aortic sinus (sinus of Valsalva) may present as a continuous murmur. This is an uncommon cause of continuous murmur One may hear it at the aortic area and along the left sternal border. Types and disease associations
Continuous machinery murmur, at the left upper sternal border
Classic for a patent ductus arteriosus (PDA). Signs of infants associated with serious cases of PDA are poor feeding, failure to thrive and respiratory distress. Other examination findings may include widened pulse pressures and bounding pulses. Systolic murmur loudest below the left scapula
Classic for a coarctation of the aorta. Coarctation of the aorta is narrowing of the aorta. This can occur in Turners Syndrome, (gonadal dysgenesis). Turners Syndrome is an X-linked disorder with absence of one X-chromosome. Other exam findings of coarctation of the aorta include radio-femoral delay. This is when the femoral pulse is later than the radial pulse. The pulses in the lower extremity may be weaker than those of the upper extremity. Another exam finding is of varying blood pressure in the upper and lower extremities.