As the heart muscle weakens, it loses pumping efficiency. The ventricles become limp and enlarged, and they cannot contract with the same strength or coordination as before. As a result, the heart chambers may not completely empty with each beat, and blood and oxygen flow to the body are poor. This inability of the heart to pump efficiently and meet the body's needs is known as heart failure. However, the causes all have one thing in common-the heart muscle is somehow damaged, and it can no longer pump effectively.
Men are at higher risk than women for heart failure, although the difference narrows with age.
High blood pressure, also called hypertension, occurs when the body's smaller vessels narrow and create higher pressure in the circulatory system. The heart must work harder to pump against this higher pressure in the vessels. Although the body can tolerate increased blood pressure for months and even years, eventually the heart can enlarge and be damaged. The heart has its own network of arteries, called coronary arteries, which carry oxygen-rich blood to the heart's muscular walls. If blood flow to the muscle is interrupted, an injury occurs that is commonly known as a heart attack.