The subcutaneous implantable cardioverter defibrillator in 2019 and beyond

A Primer on Pacemakers and Defibrillators for Nurses

Although the concepts of pacing have been around for more than half a century, technological advances in cardiac implantable electronic devices (CIEDs) have changed the landscape for patients in need of pacing support or sudden death prevention. Nurses encounter patients with CIEDs in all aspects of the health care setting. Because exciting CIED therapies are on the horizon, nurses must stay up-to-date to promote optimal outcomes for CIED patients. This essential guide provides nurses with a comprehensive overview of the principles of pacing and implantable cardioverter defibrillators (ICDs), as well as innovative technologies such as leadless cardiac pacemakers and subcutaneous ICDs.

Evolution of extravascular implantable cardioverter-defibrillator therapy for ventricular arrhythmias

Implantable cardioverter-defibrillators have become an established therapy for the prevention of sudden cardiac death due to life-threatening ventricular arrhythmias in the last decades. In all those years, the use of transvenous leads has proven to be the most vulnerable part of the system. The development of the completely subcutaneous implantable cardioverter-defibrillator opened a new era of device therapy outside of the vascular system. The next step, enabling extravascular devices with the option of antitachycardia pacing, is just around the corner. This may become an important option for all patients without a bradycardia pacing indication that are in need for antitachycardia pacing because of monomorphic ventricular tachycardia.

Effects and Complications of Subcutaneous Implantable Cardioverter-Defibrillator in the Prevention of Sudden Cardiac Death: A Narrative Review

An implantable cardioverter-defibrillator (ICD) is one of those devices that is a big boom for the prevention of sudden deaths due to heart failure. This particular device has been in use for just a couple of years, but its impact in the domain has brought about a considerable change in the way a specific issue of the cardiovascular system is tackled. Although subcutaneous or hypodermic implantable cardioverter-defibrillator (S-ICD) is considered to be a better alternative as far as transvenous implantable cardioverter-defibrillator (TV-ICD) is concerned, the former, being a newer introduction in the market, needs to be assessed in depth to clearly understand its effects and complications. Various types of research have been conducted on the efficacy of this device, and in most of the studies, the supremacy of this device is clearly evident when compared with other devices that are used for the same purpose. Better innovations in subcutaneous or hypodermic implantable cardioverter-defibrillators would enable them to be manufactured in a more efficient and cost-effective way so that a huge lot of people are benefited from this device. This review article is a whole peep into the various studies done in this domain, thereby providing adequate scientific insights about subcutaneous or hypodermic implantable cardioverter-defibrillators in a very simple and comprehensive manner.

Management of ventricular tachycardia in patients with ischaemic cardiomyopathy: contemporary armamentarium

Worldwide, ∼4 million people die from sudden cardiac death every year caused in more than half of the cases by ischaemic cardiomyopathy (ICM). Prevention of sudden cardiac death after myocardial infarction by implantation of a cardioverter-defibrillator (ICD) is the most common, even though not curative, therapy to date. Optimized ICD programming should be strived for in order to decrease the incidence of ICD interventions. Catheter ablation reduces the recurrence of ventricular tachycardias (VTs) and is an important adjunct to sole ICD-based treatment or pharmacological antiarrhythmic therapy in patients with ICM, as conclusively demonstrated by seven randomized controlled trials (RCTs) in the last two decades. However, none of the conducted trials was powered to reveal a survival benefit for ablated patients as compared to controls. Whereas thorough consideration of an early approach is necessary following two recent RCTs (PAUSE-SCD, BERLIN VT), catheter ablation is particularly recommended in patients with recurrent VT after ICD therapy. In this context, novel, pathophysiologically driven ablation strategies referring to deep morphological and functional substrate phenotyping based on high-resolution mapping and three-dimensional visualization of scars appear promising. Emerging concepts like sympathetic cardiac denervation as well as radioablation might expand the therapeutical armamentarium especially in patients with therapy-refractory VT. Randomized controlled trials are warranted and on the way to investigate how these translate into improved patient outcome. This review summarizes therapeutic strategies currently available for the prevention of VT recurrences, the optimal timing of applicability, and highlights future perspectives after a PAUSE in BERLIN.

Non-transvenous ICD therapy: current status and beyond

Subcutaneous implantable cardioverter/defibrillators (S-ICDs) have been developed to offer ICD treatment to patients without venous access to the heart and to overcome complications associated with transvenous leads, particularly lead fracture/insulation defects and endocarditis. Several studies and registries have demonstrated the feasibility and safety of S‑ICD in different groups of patients. Further developments in S‑ICD technology involve the combination with devices that can provide anti-bradycardia and anti-tachycardia pacing if needed. The extravascular ICD (EV-ICD) is a new system that similarly offers ICD therapy without a transvenous lead but uses a substernal instead of a subcutaneous lead to facilitate detection of ventricular fibrillation and to provide anti-tachycardia and also temporary anti-bradycardia pacing. The first animal but also clinical data on EV-ICDs have been published. This review discusses the current state, potential advantages and limitations, and future research of both S‑ICD and EV-ICD.

Subcutaneous implantable cardioverter defibrillator: Can it overtake its transvenous counterpart

Over the past decade, the emergence of the subcutaneous implantable cardioverter defibrillator (S-ICD) has provided cardiologists with an option to provide both primary or secondary prevention treatment of sudden cardiac death (SCD) without the associated risks that come with the use of intracardiac leads. S-ICD may prove to be a useful option in those who are young, have thromboembolic risk, immunodeficiency states, unfavorable anatomy due to adult congenital heart disease (ACHD). This article reviews the existing literature to determine whether S-ICD can prove to be a safe alternative in comparison to Transvenous implantable cardioverter defibrillator (TV-ICD) and in which patient population should S-ICD be considered over TV-ICD.

Rationale and feasibility of the atrioventricular single-lead ICD systems with a floating atrial dipole (DX) in clinical practice

Cardiac implantable electronic devices establish proper therapy for the prevention of sudden cardiac death, significantly reducing the morbidity and mortality of patients with arrhythmias and heart failure. It is well-known that the number of electrodes increases the risk of complications. To preserve the benefit of atrial sensing without the need to implant an additional lead, a single-lead ICD system with a floating atrial dipole (DX ICD lead) has been developed. Besides all of the potential benefits, the necessity of a reliable and stable atrial sensing via the floating dipole could be the main concern against the use of this lead type. In the current generation of DX devices, the specially filtered atrial signal seems to be high enough and stable over time, which is crucial in the early detection of atrial arrhythmias, discrimination between different forms of tachycardias in order to prevent inappropriate ICD therapy, and achieving an optimal atrioventricular and interventricular synchrony in patients with a two-lead CRT-DX system. The present review summarizes the benefits and potential drawbacks of the DX ICD systems based on the available literature, furthermore, proposes an evidence-based algorithm of ICD type selection.

Approaches to Minimizing Periprocedural Complications During Subcutaneous Implantable Cardioverter-defibrillator Placement

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is the latest option among devices clinically available for the prevention of sudden cardiac death, with experience from previous trials and postmarketing studies supporting the feasibility and safety of this kind of system. The extracardiac positioning of the S-ICD obviates the need for transvenous leads, which translates into lower incidence rates of lead-related complications and systemic infections. This review will highlight the results of pertinent studies related to the perioperative management of S-ICDs and review potential approaches to minimizing the risk of complications such as hematoma at the pulse generator location, unsuccessful defibrillation due to suboptimal S-ICD lead and generator positioning, and postoperative pain. An extensive literature search using PubMed was conducted to identify relevant articles.