Heart failure describes a condition in which the heart cannot pump enough blood to meet the demands of the cells throughout the body. Heart failure occurs when the heart becomes weak due to added strain caused by conditions such as coronary artery disease, high blood pressure or diabetes. The renal system which includes the kidneys, renal artery, renal vein, ureters, bladder and urethra functions to produce and release urine. The health of the cardiovascular system, including the heart, affects the ability of the renal system to function.
Lack of Blood Flow
Heart failure affects approximately 5.7 million people in the United States and accounts for approximately 300,000 deaths per year, according to the National Heart Lung and Blood Institute. The heart contains four chambers; the two upper chambers known as the atria and the two lower chambers known as the ventricles. The ventricles contract to pump blood.
Conditions that cause the heart to work harder, such as high blood pressure, can cause the walls in the heart to become stiff, therefore interfering with their ability to contract. When the ventricles cannot contract fully, they fail to propel all the blood out of the heart. This deprives the body, including the renal system, of oxygenated blood resulting in heart failure.
Damage to the Kidneys
The kidneys contain millions of tiny blood vessels. As blood flows through these vessels the kidneys filter out excess water, salts and waste products. When the blood flow decreases, the blood vessels in the kidney constrict to help increase blood pressure in order to keep a sufficient amount of blood flowing to the rest of the body, as described by the American Heart Association. Over time, this added strain on the kidneys results in damage that interferes with the ability of the kidney to filter blood effectively.
Fluid Retention
One of the hallmark symptoms of heart failure, also called congestive heart failure, is the buildup of fluid in the lungs or the feet, legs, arms and abdomen. Right-sided heart failure interferes with the ability of the right ventricle to pump enough blood to the lungs. Because blood fails to propel forward, it backs up in the tissues in the body, especially the feet, legs and abdomen.
Left-sided heart failure occurs with the left ventricle fails to pump oxygenated blood out of the heart to the body. This causes a backup of blood, and therefore fluid, in the lungs resulting in difficulty breathing and shortness of breath.
The renal system should remove excess fluid from the body; however, kidneys damaged by heart failure fail to remove excess water from the blood. Although in the short term this helps to increase the flow of blood to the body, the weakened heart in heart failure cannot handle the added volume therefore worsening the heart failure. If left untreated, heart failure can lead to kidney failure that requires either dialysis or a kidney transplant.
