The use of a stethoscope to auscultate the heart valves and their sounds at varying anatomical locations.
In healthy adults, auscultation will usually reveal two sounds described as œlub (S1) and œdub(S2), with the former occurring with the closure of the atrio-ventricular valves and the later occurring with the closure of the semilunar valves. In addition to the aforementioned sounds, other sounds may be present and are often pathological, these include: heart murmurs, gallop rhythms, adventitious sounds and S3 and S4.
With the patient lying inclined at around approximately forty-five degrees, locate the following anatomical landmarks and place your stethoscope over these to listen to the heart valves:
1. The fifth intercostal space at approximately one cm medial to the mid-clavicular line. This corresponds to the mitral valve.
2. The fourth intercostal space, at the lower left border of the sternum. This corresponds to the tricuspid valve.
3. The second right intercostal space corresponds to the aortic valve.
4. The second left intercostal space corresponds to the pulmonary valve.
The heart is auscultated in the order described above: mitral, tricuspid, aortic and pulmonary valves.
Heart sounds and their interpretation:
1. Sound one (S1): The intensity level of the first sound (S1) is proportional to the contractility of the left ventricle. Therefore an increased sound may be indicative of: mitral valve stenosis, short PR interval (electrocardiography), increased heart rate and contractility.
A reduced S1 may be attributed to mitral valve regurgitation, reduced heart rate, reduced contractility and/or a long PR interval. Varying intensity of S1 may be indicative of intermittent heart block.
2. Sound two (S2): An abnormally loud S2 is indicative of high blood pressure as the valves are shut forcefully. Physiologically the sound is spilt in inspiration. This due to the delay in pulmonic valve closure due to increased venous return.
Abnormally increased splitting may be indicative of Right Bundle Branch Block (RBBB) and pulmonic stenosis.
3. Sound three (S3): A low pitched mid diastolic (heart relaxation) sound. The occurrence of S3 is linked to abrupt changes in wall motion during ventricular filling in diastole. This is normal in children/adolescents and adults below the age of forty. Otherwise this presentation may be indicative of dilated congestive heart failure.
4. Sound four (S4): A late diastolic sound created by atrial contraction against a stiff ventricle and is usually pathological at any age. Usually indicative of diastolic dysfunction and hypertrophic cardiomyopathy.
Other sounds: heart murmurs are sounds created by turbulent blood flow. Murmurs can be benign or pathological, with the later often the result of stenosis of a heart valve, valvular insufficiency and/or regurgitation. These are graded from 1 (very faint) to 6 (very loud with thrill).
S4 is called a presystolic gallop or atrial gallop. This gallop (S4) is created by the sound of blood being forced/pushed into a rigid hypertrophic ventricle.
Cardiologists are experts in their fields with years of experience. The detection of subtle sounds by an untrained ear can be extremely difficult. It is advisable to refer when in doubt and/or if any warning signs are detected.