Inappropriate Subcutaneous Implantable Cardioverter Defibrillator Shocks Secondary to Cardiac Remodeling: A Unique Case of T Wave Oversensing.

Implantable cardioverter defibrillators (ICD) are used for the primary and secondary prevention of sudden cardiac death (SCD). Currently, two different modalities of ICDs are in use: transvenous (TV) and subcutaneous (S-ICD). The use of S-ICDs has been driven by several potential benefits of this technology: preservation of central venous vasculature, no risk of vascular or myocardial injury during implant, easier explanation, and lower risk of systemic infections. Inappropriate shocks are defined as shocks delivered for non-life-threatening arrhythmias or because of oversensing. Here, we present a case of a 58-year-old man who began experiencing inappropriate shocks three years after S-ICD placement. Careful analysis of the ICD showed T wave oversensing with no malfunction of the device. The shocks persisted even after reprogramming, leading to subsequent ICD removal and loop recorder implantation. The onset of shock episodes coincided with the improvement of left ventricular ejection fraction (LVEF). To the best of our knowledge, this is the first published report of cardiac remodeling leading to uncorrectable T wave oversensing that subsequently required S-ICD explant. This represents a potentially important limitation of S-ICD technology, especially as S-ICD use rises and medical therapy for cardiomyopathy continues to improve.

Anaphylaxis after low dose intravenous vitamin K.

Over-anticoagulation from warfarin is a common occurrence, and these patients are often referred to the Emergency Department for further treatment. Unfortunately, there is little guidance in the Emergency Medicine literature for the management of such patients. The American College of Chest Physicians (ACCP) issued guidelines in 1998 that address the use of vitamin K for patients with over-anticoagulation. However, there is still debate as to the optimal dose and route of vitamin K administration. This case report describes a patient who was treated with intravenous vitamin K within the scope of these guidelines at a very low dose (1 mg) and had a fatal anaphylactic reaction. This article will further discuss this patient, the 1998 ACCP guidelines, and the data supporting the alternative of subcutaneously administered vitamin K for patients with over-anticoagulation with no active bleeding.