Heart Failure

Heart Failure

Introduction

The heart has two atria (right atrium and left atrium) that make up the upper chambers of the heart, and two ventricles (left ventricle and right ventricle) that make up the lower chambers of the heart. The ventricles are muscular chambers that pump blood when the muscles contract. The contraction of the ventricle muscles is called systole (Gatzoulis 2009).

Many diseases can impair the pumping action of the ventricles. For example, the muscles of the ventricles can be weakened by heart attacks, infections (myocarditis) or toxins (alcohol, some chemotherapy agents). The diminished pumping ability of the ventricles due to muscle weakening is called systolic dysfunction. After each ventricular contraction (systole) the ventricle muscles need to relax to allow blood from the atria to fill the ventricles. This relaxation of the ventricles is called diastole.

Diseases such as hemochromatosis (iron overload) or amyloidosis can cause stiffening of the heart muscle and impair the ventricles' capacity to relax and fill; this is referred to as diastolic dysfunction. The most common cause of this is longstanding high blood pressure resulting in a thickened (hypertrophied) heart. Additionally, in some patients, although the pumping action and filling capacity of the heart may be normal, abnormally high oxygen demand by the body's tissues (for example, with hyperthyroidism or anemia) may make it difficult for the heart to supply an adequate blood flow (called high output heart failure) (Achten 2003).

Causes of heart failure

Many disease processes can impair the pumping efficiency of the heart to cause heart failure. In the United States, the most common causes of heart failure are:

Coronary artery disease

High blood pressure (hypertension)

Longstanding alcohol abuse

Disorders of the heart valves

Unknown (idiopathic) causes, such as after recovery from myocarditis

Less common causes include viral infections of the stiffening of the heart muscle, thyroid disorders, disorders of the heart rhythm, and many others. It should also be noted that in patients with underlying heart disease, taking certain medications can lead to the development or worsening of heart failure. This is especially true for those drugs that can cause sodium retention or affect the power of the heart muscle. Examples of such medications are the commonly used nonsteroidal anti-inflammatory drugs (NSAIDs), which include ibuprofen (Motrin and others) and naproxen (Aleve and others) as well as certain steroids, some medication for diabetes (such as rosiglitazone [Avandia] or pioglitazone [Actos]), and some calcium channel blockers (Gatzoulis 2009).

Symptoms

The symptoms of heart failure vary among individuals ...