Mechanism of hyperkalemia-induced cardiac arrest

The mechanisms by which hyperkalemia leads to cardiac arrest include myocardial cell alterations, disruption of intracellular potassium balance, and calcium ion influx, as detailed below:

1. Myocardial Cell Alterations

Hyperkalemia affects the electrical potential of myocardial cells, making the cell membrane potential unstable. When the membrane potential reaches a certain threshold, it triggers an action potential in myocardial cells, resulting in heart contraction. However, when serum potassium levels are excessively high, the myocardial cell membrane potential becomes suppressed, preventing sufficient action potentials from being generated. This can lead to cardiac arrest.

2. Disruption of Intracellular Potassium Balance

Hyperkalemia disrupts the balance of potassium ions across the myocardial cell membrane and within the cell, leading to elevated intracellular potassium concentrations. This destabilizes the myocardial cell membrane potential, increasing the risk of arrhythmias, which may ultimately result in cardiac arrest.

3. Calcium Ion Influx

Hyperkalemia may impair calcium ion influx into myocardial cells, thereby affecting their contractile function. This reduces the heart's ability to pump blood effectively, potentially causing arrhythmias and cardiac arrest.

In addition to the above mechanisms, hyperkalemia can also interfere with the heart's conduction system. If cardiac arrest occurs, immediate cardiopulmonary resuscitation (CPR) and appropriate medical treatment should be initiated to restore normal cardiac function as quickly as possible.