Auscultating heart sounds. Listening to the heart provides a way for clinicians to assess heart valve function. This video will describe the events that coincide with normal heart sounds, and demonstrate the procedure for listening to heart sounds. During each heartbeat, there are usually two sounds that are heard. The first, or S1, is described as a "lub" sound. The second, or S2, is described as a "dup" sound. The closing of the heart valves causes vibrations in the blood and heart wall. S1 occurs as the atrioventricular valves, specifically the tricuspid and mitral valves, close. The mitral valve is also known as the bicuspid valve. During the cardiac cycle, the closure of the atrioventricular valves signals the beginning of ventricular systole, contraction of the ventricles. S2 is a result of this semilunar valves, pulmonary and aortic valves, closing. Recall that during the cardiac cycle, the closure of the semilunar valves signals the beginning of ventricular diastole, relaxation of the ventricles. The first heart sound occurs at the beginning of systole. And the second heart sound occurs at the end of systole. The pause that we hear in between each heartbeat is the heart relaxing. The next heart sound is heard after the pause. Let's check your understanding. The first heart sound is associated with all of the following except-- mitral valve closure, tricuspid valve closure, the beginning of diastole, atrioventricular valve closure? The tricuspid and mitral valves are atrioventricular valves. Their closing is associated with the first heart sound. Diastole begins following the second heart sound. Before using the stethoscope, use an alcohol swab to disinfect the earpieces and the diaphragm. Allow the alcohol to dry. When you push the earpieces together, they should point away from you, like the tip of your nose. To begin your auscultation of the heart sounds, place the diaphragm over the apex of the heart. The apex is located in the fifth intercostal space in line with the middle of the left clavicle. It is also possible to hear each of the individual valve sounds by positioning the stethoscope over specific thoracic regions. The best location to hear these sounds is not superficial to the valve but lateral and oblique from the valve, because the sound travels along this path to reach the chest wall. Let's check your understanding. Which of the following valve sounds is incorrectly paired with the stethoscope positioning-- pulmonary valve/second intercostal space, left of the sternal margin; aortic valve/ second intercostal space, right of the sternal margin; mitral valve/ fourth intercostal space, over the heart apex? The mitral valve is best heard by positioning the diaphragm of the stethoscope over the fifth intercostal space, roughly in line with the middle of the left clavicle. Note that there are normal variations of where the tricuspid valve is heard. If you have difficulty hearing in the right sternal margin, slide the diaphragm over the sternum in the same line and listen. Lastly, you can try sliding in the same line over the left sternal margin.