The fourth heart sound (S4), also known as the “atrial gallop,” occurs just before S1 when the atria contract to force blood into the left ventricle. If the left ventricle is noncompliant ...

The main normal heart sounds are the S1 and the S2 heart sound. The S3 can be normal, at times, but may be pathologic. A S4 heart sound is almost always pathologic. Heart sounds can be described ...

Neither the S4’s revised styling nor its refreshed interior are likely to set the heart racing, and pressing the starter button to hear a diesel fire into life – even a diesel six – is ...