Overview
The normal phase legend divides the modeled cycle into atrial systole, isovolumic contraction, rapid ejection, reduced ejection, isovolumic relaxation, rapid filling and reduced filling/diastasis. Labels change when regurgitation or continuous drainage removes an isovolumic phase. With acute severe aortic regurgitation, volume rises during relaxation before mitral opening; there is no true isovolumic relaxation.
The ECG marker additionally identifies the electrical segment it occupies, such as a P wave, PR interval, Q/R/S component, ST segment or T wave. Electrical and mechanical events are related but are not identical labels.
The available organized atrial event depends on rhythm. Use the displayed rhythm-specific interpretation when no normal P wave or coordinated atrial contraction exists.