So, what physically creates Heartbeat 1? It is not, as many assume, the contraction of the heart muscle itself. Instead, S1 is the sound of the atrioventricular (AV) valves slamming shut. Specifically, it is the closure of the mitral valve (left side) and the tricuspid valve (right side). As the ventricles contract, pressure inside them skyrockets, forcing these valves to snap closed to prevent blood from leaking backward into the atria. That snapping vibration is Heartbeat 1 .
: During this relaxation phase, the heart's ventricles open up to receive blood pouring in from the upper atria. heartbeat 1
The interval between ventricular depolarization and repolarization. So, what physically creates Heartbeat 1
Occasional ectopic beats do not damage the heart because they are "non-sustained" irregularities. However, the British Heart Foundation and Harvard Health advise seeking immediate medical attention if palpitations are accompanied by: or shortness of breath. Dizziness or fainting (syncope). Specifically, it is the closure of the mitral