Physical Examination: Difference between revisions

===Cardiac Auscultation===

The acceleration and deceleration of blood and the subsequent vibration of the cardiac structures during the phases of the cardiac cycle are causing heart sounds. 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 heart beat. These are the first heart sound (S1) and second heart sound (S2), produced by the closing of the atroventricular valves and semilunar valves respectively. In addition to these normal sounds, a variety of other sounds may be present including heart murmurs, adventitious sounds, and gallop rhythms S3 and S4.To hear cardiac sounds, use a stethoscope with a bell and a tight diaphragm. The bell is best used to hear low-frequency sounds which are associated with ventricular filling. The diaphragm is best used to appreciate the medium-frequency sounds that are associated with valve opening and closing. Cardiac murmurs are caused due to turbulent blood flow and are usually high-to-medium frequency. In most cases the diaphragm is best used to hear cardiac murmurs. An important exception to this is the low-frequency atrioventricular valve inflow murmurs, such as that produced by mitral stenosis, which are best heard with the bell. Murmurs may be physiological or pathological. Abnormal murmurs can be caused by stenosis restricting the opening of a heart valve, resulting in turbulence as blood flows through it. Abnormal murmurs may also occur with valvular insufficiency (or regurgitation), which allows backflow of blood when the incompetent valve closes with only partial effectiveness.