Cardiac Function - Introduction

The primary function of the heart is to impart energy to blood in order to generate and sustain an arterial blood pressure necessary to provide adequate perfusion of organs. The heart achieves this by contracting its muscular walls around a closed chamber to generate sufficient pressure to propel blood from the cardiac chamber (e.g., left ventricle), through the aortic valve and into the aorta.

Each time the heart beats, a volume of blood is ejected. This stroke volume (SV), times the number of beats per minute (heart rate, HR), equals the cardiac output (CO).

CO = SV × HR

Stroke volume is expressed in ml/beat and heart rate in beats/minute. Therefore, cardiac output is in ml/minute. Cardiac output may also be expressed in liters/minute.

Related topic:  Measurement of Cardiac Output

RK Revised 04/02/07