Which of the following symptoms can occur from theophylline toxicity related to heart function?

Theophylline is a medication commonly used to treat respiratory diseases such as asthma or COPD, and it works as a bronchodilator. However, one of the potential adverse effects of theophylline, particularly in cases of toxicity, is the stimulation of the central nervous system and cardiovascular system.

Tachycardia, or an increased heart rate, is a direct result of theophylline's mechanism of action; it promotes catecholamine release, which can lead to increased heart rate. When toxic levels of theophylline are reached, this sympathetic stimulation can be magnified, resulting in significant tachycardia.

The risk of tachycardia becomes especially pronounced in situations where theophylline is given at higher doses, or in individuals with diminished metabolic clearance (e.g., due to liver disease or other conditions that impair drug metabolism). In toxic situations, the heart’s rhythm can be significantly altered, leading to a rapid heartbeat which may require medical intervention.

Other symptoms associated with theophylline toxicity can include gastrointestinal disturbances or CNS effects, but the emphasis here is on heart function. While other heart-related effects may occur, tachycardia stands out as a common consequence directly linked to the overdose or toxicity of theophylline,