How Do High Potassium Levels Affect Heart?

Potassium is a mineral that plays an important role in the body, which carefully regulates potassium levels due to the importance of this mineral for the function of all cells, including muscle cells within the heart. Having too much potassium in your blood can disrupt the heart's ability to pump properly.

Smiling patient having his blood pressure taken by nurse. (Image: Comstock/Stockbyte/Getty Images)

Potassium as Electrolyte

One of the reasons why potassium is so important is because it carries a positive charge when it is dissolved in water-based substances, such as blood. Cells within the body use small electrical charges to function normally. By modulating their potassium levels, cells can change their electrical charges. Most of the potassium within the body is kept in cells, but alterations in blood levels in potassium can have a significant effect on the body.

Potassium and Cardiac Function

The contraction of the heart involves electrical currents. The contraction of cardiac muscle fibers requires calcium. The release of calcium from internal stores is controlled by changes in the electrical charge within the cell. Because potassium plays a pivotal role in maintaining this electrical charge, fluctuations in potassium levels can disrupt calcium release within the heart, disrupting the timing and rhythm of cardiac muscle contractions needed for the heart to pump blood efficiently throughout the body.

Hyperkalemia and Cardiac Problems

Hyperkalemia is a condition in which potassium levels in the blood get too high. If you have hyperkalemia, one test that might be run is called an electrocardiogram, or EKG. This test measures the electrical activity of the heart and can be used to detect cardiac arrhythmias. Hyperkalemia can result in an abnormal EKG, which means the timing of the contractions in the different parts of the heart are disrupted, the Merck Manual notes. Cardiac arrhythmias can cause low blood pressure and can cause the heart to cease pumping entirely.

Causes

Hyperkalemia is generally not caused by consuming too much potassium in your diet. Your body excretes excess potassium in your urine. Consequently, most cases of hyperkalemia are caused by problems with your renal system. Hyperkalemia can also be caused by an imbalance of a hormone known as aldosterone. Treatment for hyperkalemia typically focuses on maintaining the heart's normal rhythm while also working to get potassium levels back to normal.