Congestive Heart Failure

The heart is composed of two independent pumping systems, one on the left side and one on the right. The right chamber, or right atrium, of the heart relaxes and expands to fill with blood that has returned from the body. (This relaxed action causes diastolic pressure, recorded as the second and lower number when measuring blood pressure). The used blood is poor in oxygen and rich in carbon dioxide. It enters a second muscular chamber called the right ventricle, which pumps the blood into the lungs where it exchanges the carbon dioxide for oxygen. This blood, now oxygen-rich, returns through pulmonary veins to the left atrium in the heart where it is pumped back out to the body by the left ventricle. The left ventricle has thicker muscles than the right in order to perform contractions powerful enough to force the blood through the main artery (the aorta) to all parts of the body. (This strong contraction causes systolic pressure, the first and higher number measured for blood pressure.)