restricted access 23. Iatrogenic Aspects in Cardiac Device Therapy
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INTRODUCTION The approach to cardiac pacemaker implantation has evolved over the past half­ century. The early trend from the epicardial approach to the simpler transvenous cutdown led to the percutaneous technique developed by Littleford and Spector (1). Conventional pacing systems consist of a pacemaker containing electronics and battery typically implanted in a subcutaneous pocket in the chest. One or more leads threaded from the device pocket through veins into the heart conduct the pacing therapy to the desired pacing site. Transvenous pacemaker therapy has become the standard of care for vari­ ous bradyarrhythmias, improving quality of life and reducing patient mortality (2). Since Michel Mirowski and his team implanted the first implantable cardioverter-­ defibrillator (ICD) in 1980 (3,4), the evolution of the ICD has been comparable with that of the cardiac pacemaker. The initial epicardial ICD placement with an abdominal pocket has given way to a transvenous approach and a pectoral submuscular pocket. Multiple clinical ­ trials have shown the benefit of ICD for the primary and secondary prevention of sudden cardiac death (3–8). The advent of cardiac resynchronization therapy (CRT) has added a new level of complexity to pacemaker and defibrillator implantation. Not only is a third lead required, but also reliable left ventricular stimulation is essential for positive clinical results. CRT reduces morbidity and mortality in heart failure patients with reduced ejection fraction and left bundle branch block (9–11). Pacemakers, ICDs, CRTs, and their combined use as CRT-­ pacemakers (CRT-­ P) or CRT-­ defibrillators (CRT-­ D) are included in the current guidelines on cardiac pacing and resynchronization therapy and on treatment of chronic heart failure (2,12,13). Although all of ­ these cardiac implantable electrical devices (CIEDs) are effective , approximately 10% of patients experience complications, often related to the leads or the device pocket. Device complications are associated with increased patient morbidity, health care costs, and even mortality (14–16). Much of the published data on ­ these complications is based on secondary analyses of controlled randomized studies, observational single-­ center studies, or registry-­ based studies. In Denmark and Sweden, patients with CIEDs are included in nationwide registries that provide a large amount of prospective data. In general, short-­ term (periprocedural) complications can be distinguished from long-­ term complications. The majority of complications emerge shortly ­ after or even CHAPTER 23 Iatrogenic Aspects of Cardiac Device Therapy Susanne Röger and Jürgen Kuschyk 272 / Iatrogenic Aspects in Cardiac Device Therapy brought new challenges to device implantation with re­ spect to venous access, coronary sinus cannulation, lead positioning, and effective stimulation (23). The success rate is strongly related to the complexity of the patient’s anatomy and to the experience of the implanter. All of ­ these­ factors must be taken into account when planning a device implantation. The operator should weigh the potential benefit of the CIED against the potential risk of the operation, especially in el­ derly, frail, and multimorbid patients. The most common short-­ term complications are pneumothorax, pocket hematomas, and lead dislodgments. Cardiac perforation with or without tamponade, hematothorax, air embolism, or damage to the tricuspid valve occur infrequently (17), but in some of ­ these cases acute surgical interventions are inevitable. Patients should be informed about ­ these potential complications as well as the general risks of surgery, such as anesthesia-­ related complications, cerebrovascular accidents, and lung embolism. Arrhythmias During the operation itself, some patients suffer from arrhythmias. Asystole can occur through a vagal reaction. In patients with a third-­ degree atrioventricular (AV) block, ventricular escape rhythm may get lost through the occurrence of extrasystoles (induced through lead implantation or device testing). Usually tachycardiac arrhythmias that occur during lead implantation are nonsustained . In rare cases, amiodarone or external cardioversion is needed. During CRT implantation , placement of the left ventricular electrode can cause right bundle branch block. In patients with a pre-­ existing left bundle branch block, development of right bundle branch block can cause complete AV-­ block without an escape rhythm. Hematoma Pocket hematoma is a common complication following CIED implantation. The source of bleeding may be the pocket itself or bleeding from the vein around the lead entry site. Hemostasis may be achieved using electrocautery while creating the pocket. Other­ wise, figure-­ eight suture placement and manual compression may be needed. The range in hematoma size varies from a contained, small amount of fluctuance to a large hematoma during the implantation pro­ cess (17,18) and are related to the procedure itself. Long-­ term complications are related mostly to the intracardiac leads, the Achilles heel...