The Physiological Versus The Pathological S3

1. What is the difference in timing and quality between the physiological and the pathological S3?

ANS: None, except that the S3 found in constrictive pericarditis may occur earlier than usual.

2. How can you usually tell a physiological from a pathological S3?

ANS: Only by knowing the circumstances under which it occurs, i.e., by finding the reason for the pathological S3, such as symptoms and signs of heart failure or myocardial abnormalities.

Note: Some patients with a pathological S3 secondary to a past infarction are relatively asymptomatic, i.e., they do not seem to have the decreased exercise tolerance that is the usual consequence of a high left atrial V wave. The S3 in these patients is often associated with a ventricular aneurysm or a large akinetic area. The mechanism for this S3 is unknown.

3. Is the physiological S3 ever as loud as the loudest pathological S3?

ANS: Almost. Conversely, a pathological S3 may be very faint.

4. What noise may follow the pathological S3? When is this heard with the physiological S3?

ANS: A short diastolic rumble is often heard following the pathological S3. It is also heard with the torrential flow through the mitral valve that occurs when the physiological S3 is exaggerated either by MR or by a PDA.

5. When does a high filling pressure not mean LV dysfunction and low ejection fraction?

ANS: If it is caused primarily by a high A wave, because a strong left atrial contraction can produce a high A wave at the end of diastole and so cause a high filling pressure, despite a normal ejection fraction. This is because it is the mean and not the end-diastolic filling pressure that best correlates with cardiac dysfunction. For example, in severe aortic stenosis there may be a 20-mm LV end-diastolic pressure but a mean left atrial pressure of 10 mm, and therefore no decreased function.

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  • Heike Huber
    How does physiological s3 occurs?
    2 years ago

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