Heart sounds

In cardiac auscultation, an examiner may use a stethoscope to listen for these unique and distinct sounds that provide important auditory data regarding the condition of the heart.

In healthy adults, there are two normal heart sounds, often described as a lub and a dub that occur in sequence with each heartbeat.

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 (regurgitation), which allows backflow of blood when the incompetent valve closes with only partial effectiveness.

It is caused by the closure of the atrioventricular valves, i.e. tricuspid and mitral (bicuspid), at the beginning of ventricular contraction, or systole.

The papillary muscles are attached to the cusps or leaflets of the tricuspid and mitral valves via chordae tendineae (heart strings).

When the papillary muscles contract, the chordae tendineae become tense and thereby prevent the backflow of blood into the lower pressure environment of the atria.

The S1 sound results from reverberation within the blood associated with the sudden block of flow reversal by the valves.

[1] The rarer extra heart sounds form gallop rhythms and are heard in both normal and abnormal situations.

The sound occurs just after atrial contraction at the end of diastole and immediately before S1, producing a rhythm sometimes referred to as the "Tennessee" gallop where S4 represents the "Ten-" syllable.

[2] It is best heard at the cardiac apex with the patient in the left lateral decubitus position and holding their breath.

However, with the advent of better quality and wider availability of echocardiography and other techniques, heart status can be recognized and quantified much more accurately than formerly possible with only a stethoscope, examination, and experience.

The decreased (more negative) intrathoracic pressure has an opposite effect on the left side of the heart, making it harder for the blood to exit into circulation.

Increasing venous blood return to the right side of the heart by raising a patient's legs to a 45-degree while lying supine produces similar effect which occurs during inhalation.

[citation needed] There are a number of interventions that can be performed that alter the intensity and characteristics of abnormal heart sounds.

This is a characteristic scratching, creaking, high-pitched sound emanating from the rubbing of both layers of inflamed pericardium.

[6] Heart sounds result from reverberation within the blood associated with the sudden block of flow reversal by the valves closing.

The same connection can be used to listen to the previously recorded auscultation through the stethoscope headphones, allowing for a more detailed study of murmurs and other heart sounds, for general research as well as evaluation of a particular patient's condition.