A firm understanding of cardiac anatomy and the mechanical events of the cardiac cycle is essential for interpreting clinical cardiograms.
Mechanical Events & Valvular Status
- Systole: Contraction phase of the heart. Ventricular pressure rises, closing the AV valves and opening the semilunar valves.
- Diastole: Relaxation phase. Ventricles fill with blood as AV valves open.
- First Heart Sound (S1): 'Lubb' sound caused by the closure of the Atrioventricular (Tricuspid/Mitral) valves at the start of systole.
- Second Heart Sound (S2): 'Dupp' sound caused by the closure of the Semilunar (Aortic/Pulmonary) valves at the start of diastole.
