The development of the extravascular defibrillator with substernal lead placement: A new Frontier for device‐based treatment of sudden cardiac arrest

Abstract

Introduction The extravascular implantable cardioverter‐defibrillato (EV ICD) system with substernal lead placement is a novel nontransvenous alternative to current commercially available ICD systems. The EV ICD provides defibrillation and pacing therapies without the potential long‐term complications of endovascular lead placement but requires a new procedure for implantation with a safety profile under evaluation. Methods This paper summarizes the development of the EV ICD, including the preclinical and clinical evaluations that have contributed to the system and procedural refinements to date. Results Extensive preclinical research evaluations and four human clinical studies with >140 combined acute and chronic implants have enabled the development and refinement of the EV ICD system, currently in worldwide pivotal study. Conclusion The EV ICD may represent a clinically valuable solution in protecting patients from sudden cardiac death while avoiding the long‐term consequences of transvenous hardware. The EV ICD offers advantages over transvenous and subcutaneous systems by avoiding placement in the heart and vasculature; relative to subcutaneous systems, EV ICD requires less energy for defibrillation, enabling a smaller device, and provides pacing features such as antitachycardia and asystole pacing in a single system.

Efficacy and Safety of an Extravascular Implantable Cardioverter–Defibrillator

“…The extravascular ICD system and implantation procedure have been described in detail elsewhere. 13,19 In brief, the pulse generator, implanted along the patient's left midaxillary line, has a volume of 33 cm 3 and delivers shocks of up to 40 J (Fig. 1).…”

Evolution of extravascular implantable cardioverter-defibrillator therapy for ventricular arrhythmias

“…Its conception and primary evaluation process was recently described by Thompson and colleagues. 25 The pulse generator is in a similar lateral position as the S-ICD ( Figure 2 ). The benefit of this position is that the lead is placed direct above the right ventricle, assuring a good sensing and pacing location.…”

Characterization of the substernal space with computed tomography imaging in patients with and without median sternotomy: Assessing a novel implant location for extravascular defibrillation lead placement

“…In acute and chronic clinical feasibility studies, the EV ICD system has shown effective defibrillation and pacing performance with a lead positioned in the anterior mediastinum (substernal space) between the heart and sternum via a minimally invasive procedure, described previously. [8][9][10][11][12][13] While recent retrospective examination of EV ICD clinical data has demonstrated a high rate of defibrillation efficacy and a low rate of adverse events across a wide range of body habitus, 14 patients with prior sternotomy have been excluded from inclusion to date due to changes to the implant that may result from the disruption of the sternum and exposure of the substernal tissues associated with midline sternotomy. [8][9][10][11][12]15 Whether the substernal space is an applicable target for ICD lead implantation in patients with prior midline sternotomy remains an open question and requires a thorough examination of the implant environment post-sternotomy.…”

“…The extravascular ICD (EV ICD) system (Medtronic, Mounds View, Minnesota, USA) is in development to provide pacing and defibrillation therapies without an ICD lead contacting the heart or vasculature. In acute and chronic clinical feasibility studies, the EV ICD system has shown effective defibrillation and pacing performance with a lead positioned in the anterior mediastinum (substernal space) between the heart and sternum via a minimally invasive procedure, described previously 8–13 . While recent retrospective examination of EV ICD clinical data has demonstrated a high rate of defibrillation efficacy and a low rate of adverse events across a wide range of body habitus, 14 patients with prior sternotomy have been excluded from inclusion to date due to changes to the implant that may result from the disruption of the sternum and exposure of the substernal tissues associated with midline sternotomy 8–12,15 …”