Which of the following represents a cardiac symptom of digoxin toxicity?

Digoxin toxicity is known to affect the heart's rhythm significantly. When someone experiences digoxin toxicity, one of the hallmark symptoms is the occurrence of cardiac arrhythmias. These arrhythmias can manifest as irregular heartbeats, which can range from bradycardia (slow heart rate) to various types of tachycardia (fast heart rate).

Digoxin is a medication commonly used to treat heart failure and certain arrhythmias, and while it has therapeutic effects, it has a narrow therapeutic index. This means that the difference between a therapeutic dose and a toxic dose is small. When digoxin levels are too high, it leads to disturbances in the electrical conduction system of the heart, resulting in arrhythmias.

The other options do not specifically align with the characteristic symptoms of digoxin toxicity related to the heart's rhythm. For example, while increased heart rate, low blood pressure, and high blood pressure can be secondary effects related to other conditions or medications, they are not the defining symptoms associated with digoxin toxicity, making cardiac arrhythmia the most relevant and correct choice in this scenario.