Drug and defibrillator interactions.

We reviewed the interactions of drugs and defibrillators, with emphasis on implantable cardioverter defibrillators. Articles were identified by searching MEDLINE from 1966 to the present; additional sources were identified from reference lists in these articles. Drugs have the potential for both beneficial and harmful interactions with electrical therapy. Beneficial interactions include reductions in the energy required to defibrillate the heart and in the occurrence of arrhythmia resulting in decreased shock frequency, prolonged device longevity, and improved patient comfort. Potentially harmful interactions include altering the detection of ventricular tachycardia; altering the pacing threshold, resulting in interference with bradycardia or antitachycardia pacing; development of incessant ventricular tachycardia; and increasing the energy required to defibrillate the heart. As the use of implantable cardioverter defibrillators increases, pharmacists should be aware of the potential for drug-device interactions.