Perioperative Management of Cardiovascular Implantable Electronic Devices

Abstract

1titled “Perioperative Pacemaker-Mediated Tachycardia in the Patient with a Dual Chamber Implantable Cardioverter-Defibrillator.” The authors describe the management of a patient who undergoes hip surgery with ischemic cardiomyopathy and an implantable cardioverter-defibrillator (ICD) inserted for primary prevention of sudden cardiac death. This case report is an excellent demonstration of classic pacemakermediated tachycardia (PMT) in a patient with an ICD. PMT is seen in patients with a dual chamber pacemaker, whose conduction is anterograde via the pacemaker with retrograde conduction via the atrioventricular node where the activation of the atria is outside the programmed postventricular atrial refractory period (PVARP). As in this case, a premature ventricular contraction is conducted in a retrograde fashion and is improperly interpreted by the atrial channel of the pacemaker as a native atrial impulse, which initiates a paced ventricular beat. The authors correctly emphasize the difference in acute management of PMT depending on whether the device is a pacemaker or an ICD. If the device is a pacemaker, a magnet applied to the generator will result in asynchronous pacing of the heart (DOO), thus eliminating the atrial tracking and timing of a ventricular impulse. An ICD cannot be placed in asynchronous mode by applying a magnet; its pacemaker (bradycardia therapy) can only be altered by using a manufacturer-specific programmer. Extending the PVARP interval such that the atrial channel does not sense any retrograde conduction from the ventricles will also terminate a PMT. Many of the current cardiac implantable electronic devices (CIEDs) have a specialized algorithm that allows the PVARP to be automatically extended in the presence of premature ventricular contraction.