ECG and JVP waveforms. Dashed vertical lines separate the 2 phases of the cardiac cycle: systole and diastole. Each physiologic signal is annotated with the corresponding significant waves. For ECG: P corresponds to atrial depolarization, QRS complex to ventricular depolarization, and T to ventricular repolarization. For JVP: the a, c, v ascents are annotated in blue and the x, x′, and y descents in gray.