Heart Failure: Causes, Effects, and Implications
Heart failure may be defined as the failure of the heart to pump blood normally. It embraces many different conditions that lead to a failure of the heart to expel its contents adequately. When the left atrial pressure is raised, and when edema occurs predominantly in the lungs, and when the heart failure is described as left-sided; when it occurs in the systemic circulation, it is described as congestive or right-sided.
What are the Causes of Heart Failure?
The causes of heart failure may be listed as follows:
1. Myocardial diseases:
- Coronary heart disease, cardiomyopathy, infiltrative dis cases such as amyloidosis, sarcoidosis, and acute myocarditis.
- Pressure overload, in which there is increased resistance to ejection: hypertension, stenosis of the aortic or pulmonary valves, hypertrophic cardiomyopathy.
- Volume overload, in which there is increased stroke volume: insufficiency of the mitral, aortic, or tricuspid valve, and congenital left-to-right shunt.
- The increased body demands thyrotoxicosis, anemia, arteriovenous fistula.
When the heart fails, compensatory mechanisms respond to the increased workload. There is either hypertrophy (a thickening) of the heart muscle or dilatation (an enlargement) of the heart chambers.
What effect does heart failure have on the body?
In compensated heart failure, the heart can maintain adequate circulation to all parts of the body, usually by some enlargement of the heart and an increased heart rate. Patients are usually able to perform daily activities if they take care to avoid hurry, unnecessary excitement, and strenuous work. In decompensated heart failure, the heart is unable to maintain a circulation adequate for the supply of nutrients and oxygen to the tissues.
What happens when the heart fails?
When the heart fails, compensatory mechanisms respond to the increased workload. There is either a thickening of the heart muscle or an enlargement of the heart chambers.
When the cardiac output falls, the release from the kidneys increases the reabsorption of sodium from the renal tubule. Increased reabsorption of sodium leads to the increased osmolality of the serum, resulting in the retention of an equivale amount of water. Increased retention of sodium and water results in edema of dependent parts or difficulty in breathing because of the accumulation of fluids in the lungs. When the blood supply to the tissues is poor, they are depicted of nutrients and sufferers become malnourished and may lose weight. This state of malnutrition may be masked by concomitant edema: the patient then looks puffy. In cases of severe heart failure, patients are also less likely to eat properly and may become malnourished because they are not getting enough nutrients, especially protein.