- Fourth heart sound
Infobox_Disease
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ICD9 = ICD9|427.9
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MeshID =The fourth heart sound or S4 is a rare extra
heart sound that occurs immediately before the normal two "lub-dub" heart sounds (S1 and S2). It occurs just after atrial contraction and immediately before the systolic S1. This produces a rhythm classically compared to the cadence of the word "Tennessee " with the first syllable ("Ten-") representing S4.S4 is sometimes audible in healthy children and trained athletes, but is always abnormal in adults. It is a sign of a pathologic state, usually a failing left ventricle. If the problem lies with the left ventricle, the gallop rhythm will be heard best at the cardiac apex. It will become more apparent with exercise, with the patient lying on their left-hand side, or with the patient holding
expiration . If the culprit is the right ventricle, the abnormal rhythm will be most evident on the lower left hand side of thesternum and will get louder with exercise and quick, deepinspiration Tavel ME. "The appearance of gallop rhythm after exercise stress testing." "Clin Cardiol". 1996 Nov;19(11):887-91] .S4 has also been termed an atrial gallop or a presystolic gallop because of its occurrence late in the heart cycle. It is a type of
gallop rhythm by virtue of having an extra sound; the other gallop rhythm is called S3. The two are quite different, but they may sometimes occur together forming a quadruple gallop. If theheart rate is also very fast (tachycardia ), it can become difficult to distinguish between S3 and S4 thus producing a single sound called a summation gallop.Causes
S4 is caused by the
atria contracting forcefully in an effort to overcome an abnormally stiff or hypertrophic ventricle. This causes abnormal turbulence in the flow of blood that can be detected by astethoscope .Associations
The S4 rhythm is associated with anything that increases the stiffness of the ventricle, including:
*hypertrophy of the ventricle
*long-standinghypertension (causes ventricular hypertrophy)
*aortic stenosis (causes ventricular hypertrophy)
*overloading of the ventricle (causes ventricular hypertrophy)
*fibrosis of the ventricle (eg. post-MI)Treatment
The rhythm itself does not require treatment; rather plans should be laid to stop the progression of whatever causes the underlying ventricular dysfunction.
References
External links
* [http://www.familypractice.com/heartlab/heartlab.htm?main=/heartlab/Text/gallop_sounds.htm familypractice.com] - requires knowledge of medical terms
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