ATI Pathophysiology Practice Exam

An occurrence of too high of a concentration of which of the following electrolytes is associated with cardiac arrhythmias?

1. Sodium

2. Calcium

3. Potassium

4. Magnesium

The correct answer is: Potassium

The association of high concentrations of potassium with cardiac arrhythmias can be attributed to the critical role potassium plays in maintaining the resting membrane potential and repolarization phases of cardiac action potentials. Potassium ions are essential for normal electrical signaling in the heart. Elevated levels of potassium, a condition known as hyperkalemia, can disrupt this balance and lead to alterations in the electrical activity of the myocardium. When potassium levels rise, there can be changes in the action potential duration, affecting both depolarization and repolarization phases. High potassium can lead to a decrease in heart rate and may result in severe arrhythmias, such as ventricular fibrillation or even cardiac arrest. The heart's cells become less responsive to electrical impulses, which can cause irregular heart rhythms. In contrast, while other electrolytes like sodium, calcium, and magnesium also have vital roles in cardiac function, their direct relationship with arrhythmias varies. For example, elevated sodium levels can lead to fluid retention and hypertension rather than direct arrhythmogenic effects. High calcium levels can also influence the heart's electrical activity but typically do not exert the same rapid and pronounced effects on heart rhythm as hyperkalemia. Low or imbalanced magnesium can lead to arrhythmias but is less commonly