Brief Description of the Cardiac Cycle

Excerpt from Naturopathy assignment 60512

The Cardiac Cycle

A normal range of beats for the heart is 60-100 beats per minute (BPM) with a normal pulse (+2) and blood pressure less than 120/80 systole/diastole (elevated 120-140/80-90mmHg), (low below 90/60 mmHg), (high 140-190/90-100mmHg). This gives a practitioner an indication of cardiac (and kidney) health and vascular resistance.

At the first phase (1) ‘atrial contraction’ of CC Atrioventricular Valves (AV) are open and Semilunar valves (SV) are closed. Atria and ventricles are in diastole (filling). In the ‘Isovolumetric phase’ (2) all valves are closed. The pressure gradient has caused the atria to contract (systole) and forcibly pump blood past the open (AV) into the ventricles which then contract (systole) to prevent blood flowing back into the atria the AV close and make the first sound ‘lub’. In phase (3) ‘Rapid ejection’ ventricle pressure rises above two major arteries and pushes open 2 (SV) valves into the pulmonary trunk and aorta. Phase (4) ‘Reduced ejection’ The ventricles repolarise from the ejection stages and begin to relax (diastole), the AV valves remain closed to prevent blood flow back to atria. The second heart sound, S2 or dub, occurs when the semilunar valves close. In phase (5) ‘Isovolumetric relaxation’ the

(SV) valves close and the second heart sound, ‘dub’ can be heard in phases (6) and (7) Rapid and reduce filling of the atria occurs (respectively) when pressure falls and blood from the atria moves again into the ventricles the (AV) valves are again open (in diastole) and this is the completion of 1 cardiac cycle (Klabunde, PhD, 2018).

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