How Heart Failure Occurs

Disorders can cause heart failure in two ways. They can cause problems with the heart's ability to fill with blood or to pump blood out. Among older people, filling problems (called diastolic dysfunction) and pumping problems (called systolic dysfunction) are equally common.

Filling problems usually occur because the walls of the ventricles have become stiff. As a result, the ventricles cannot fill with blood normally, and too little blood is pumped out. As people age, heart muscle tends to become stiffer, making heart failure due to filling problems more likely. High blood pressure or a type of cardiomyopathy called hypertrophic cardiomyopathy can cause filling problems because either disorder can make the heart muscle thicker and stiffer.

Filling problems are not always caused by a stiff heart. They may result from thickening of the sac around the heart (constrictive pericarditis) or fluid accumulation within the sac (pericardial effusion). Either disorder can prevent the heart from expanding and filling normally. In atrial fibrillation (an abnormal heart rhythm), the atria beat rapidly and irregularly. As a result, the atria do not move enough blood into the ventricles. If atrial fibrillation occurs suddenly in older people, heart failure may result.

Pumping problems usually occur when the heart muscle has been damaged. A damaged heart pumps less blood out, causing pressure inside the heart to increase and the heart's chambers to enlarge. The most common cause of heart damage is a heart attack (due to a blockage in an artery that supplies the heart with blood). Other disorders that can damage the heart and cause pumping problems include heart valve disorders, high blood pressure, and certain infections (usually caused by viruses) and inflammatory disorders (such as lupus).

In aortic stenosis (a heart valve disorder), the opening between the left ventricle and the aorta (aortic valve) narrows. As a result, pumping blood out of the heart is harder. Aortic stenosis is a common cause of heart failure in older people.

Kidney and lung disorders can result in heart failure. If the kidneys are not functioning normally (because of a disorder or changes due to aging), they are less able to remove excess fluid and salt from the body. If extra fluid and salt accumulate in the body, the heart may have to work harder. Sometimes heart failure results. If a lung disorder such as emphysema or scarring (pulmonary fibrosis) develops, blood pressure in the lungs increases. As a result, pumping blood to the lungs is harder for the right ventricle.

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