Introduction

Introduction

To understand what occurs in heart failure, it is useful to be familiar with the how the heart works and its anatomy. The heart is composed of two independent pumping systems, one on the right side, and the other on the left. Each has two chambers, an atrium and a ventricle. The ventricles are the major pumps in the heart.

The Right Side of the Heart. The right system receives blood from the veins of the whole body. This is "used" blood, which is poor in oxygen and rich in carbon dioxide.

• The right atrium is the first chamber that receives blood.
• The chamber expands as its muscles relax to fill with blood that has returned from the body.
• The blood enters a second muscular chamber called the right ventricle.
• The right ventricle is one of the heart's two major pumps. Its function is to pump the blood into the lungs.
• The lungs restore oxygen to the blood and exchange it with carbon dioxide, which is exhaled.

The Left Side of the Heart. The left system receives blood from the lungs. This blood is now oxygen rich.

• The oxygen-rich blood returns through veins coming from the lungs (pulmonary veins) to the heart.
• It is received from the lungs in the left atrium, the first chamber on the left side.
• Here, it moves to the left ventricle, a powerful muscular chamber that pumps the blood back out to the body.
• The left ventricle is the strongest of the heart's pumps. Its thicker muscles need to perform contractions powerful enough to force the blood to all parts of the body.
• This strong contraction produces systolic blood pressure (the first and higher number in blood pressure measurement). The lower number ( diastolic blood pressure) is measured when the left ventricle relaxes to refill with blood between beats.
• Blood leaves the heart through the ascending aorta, the major artery that feeds blood to the entire body.