Potassium, classified as an essential mineral, functions as an electrolyte, which means it transmits the tiny electrical impulses between nerves. In the heart, potassium keeps your heart beating rhythmically. Your body must maintain its potassium level within a narrow range to keep cells, nerves, muscles and the heart functioning properly. Too little potassium in your blood can contribute to a heart attack, but too much potassium, such as what can occur when taking potassium chloride supplements can also affect heart function and lead to a heart attack.
Eating a healthy diet that includes a variety of fruits and vegetables provides your body with all the potassium it needs. Failing to consume the recommended daily intake of potassium, reported by the Institute of Medicine as 4,700 mg per day, leads to a potassium deficiency, a condition known as hypokalemia. More common causes of a low potassium level include the use of diuretic medications to treat high blood pressure or medical conditions that increase the excretion of potassium in the urine, such as Cushing's syndrome or aldosteronism. In these cases, your doctor may prescribe potassium chloride supplements.
Potassium and sodium work together within the body to balance the amount of fluid inside and outside of cells, and to transmit the electrical signals important for muscle contraction and heart function. The majority of potassium enters the cell, while the majority of sodium remains in the fluid surrounding the cells. This concentration difference creates an electrochemical gradient, known as the membrane potential. Your body expends 20 to 40 percent of its resting energy to maintain this sodium and potassium concentration, showing the importance of this function for supporting life, according to the Linus Pauling Institute.
Doctors must carefully monitor patients taking potassium chloride supplements, through the use of potassium serum tests and electrocardiograms that reveal heart function. Too much potassium in the blood, a condition known as hyperkalemia, can cause muscle weakness and paralysis and interrupt the normal heartbeat causing heart arrhythmia. Heart arrhythmia can lead to a heart attack or cause the heart to stop beating, known as cardiac arrest. Many states that utilize lethal injection as a form of capital punishment administer three types of medications -- including a high dose of potassium chloride to stop the heart.
A heart attack, also known as a myocardial infarction, describes a condition in which a portion of the heart fails to receive enough oxygen. If blood flow is not restored, that portion of the heart muscle becomes damaged and can die. A heart attack can occur when the coronary arteries become blocked due to the buildup of plaque. High blood pressure, known as hypertension, damages the lining of the blood vessels, which increases the risk of plaque buildup. Potassium helps to regulate blood pressure, so taking carefully monitored amounts of potassium chloride to treat a condition of low potassium can help prevent a heart attack.