What is the most common cause of junctional tachycardia?

• A. Coronary artery disease
• B. Electrolyte imbalances
• C. Digoxin toxicity
• D. Ventricular hypertrophy

Answer: (C)

Junctional tachycardia is an arrhythmia that originates from the junction between the atria and ventricles. Among the causes listed, digoxin toxicity is the most common and significant contributor to this specific type of tachycardia. Digoxin is a medication commonly used to treat heart conditions, particularly heart failure and atrial fibrillation. However, when digoxin levels become excessive in the body, it can lead to various arrhythmias, including junctional tachycardia.

The mechanism by which digoxin causes junctional rhythm involves increased vagal tone and enhanced automaticity of the junctional tissues. This results in a higher heart rate that can lead to junctional tachycardia.

In contrast, while coronary artery disease, electrolyte imbalances, and ventricular hypertrophy can all affect cardiac function and contribute to arrhythmias, they are not the primary causes of junctional tachycardia. Instead, these conditions are more commonly associated with other types of arrhythmias, rather than specifically leading to junctional tachycardia. Thus, digoxin toxicity stands out as the most prevalent cause in this context.