The Cardiac Cycle, Animation

(USMLE topics, cardiology) Phases of the cardiac cycle. The Wiggers diagram explained. Purchase PDF here: Purchase a license to download a non-watermarked copy of this video here: ©Alila Medical Media. All rights reserved. Voice by: Sue Stern. Support us on Patreon and get FREE downloads and other great rewards: The cycle is initiated with the firing of the SA node that stimulates the atria to depolarize. This is represented by the P-wave on the ECG. Atrial contraction starts shortly after the P-wave begins, and causes the pressure within the atria to increase, FORCING blood into the ventricles. Atrial contraction, however, only accounts for