A blended sensor restores chronotropic response more favorably than an accelerometer alone in pacemaker patients: the LIFE study results.

Background: Adaptive rate sensors used in permanent pacemakers incorporate an accelerometer (XL) to increase heart rate with activity. Limited data exists regarding the relative benefit of a blended sensor (BS) (XL and minute ventilation) versus XL alone in restoring chronotropic response (CR) in chronotropically incompetent (CI) patients.

Methods: One thousand five hundred thirty-eight patients from the limiting chronotropic incompetence for pacemaker recipients (LIFE) study were implanted with a pacemaker and 1,256 patients had data collected at 1 month.

Performance of a new single-chamber ICD algorithm: discrimination of supraventricular and ventricular tachycardia based on vector timing and correlation.

Aims: Interval- and morphology-based algorithms have been used in modern implantable cardioverter defibrillators (ICDs) to discriminate supraventricular tachycardia (SVT) from other rhythms. A newly developed ICD discrimination algorithm, Rhythm ID (Guidant Corporation, St Paul, MN, USA), uses both interval-based metrics and an electrogram vector timing and correlation (VTC) algorithm in a dual-chamber ICD. In a single-chamber ICD, Rhythm ID contains only the VTC component.

Defibrillation energy requirements using a left anterior chest cutaneous to subcutaneous shocking vector: implications for a total subcutaneous implantable defibrillator.

Background: Subcutaneous implantable defibrillators (ICDs) are being developed to facilitate ICD implantation.

Objective: The purpose of this study was to estimate the human defibrillation energy requirement (DER) using a left chest cutaneous (Q) to subcutaneous (SQ) shocking vector.

Methods: Twenty patients undergoing implantation of an indicated ICD were enrolled (15 males, age = 63 +/- 12 years; ejection fraction = 0.

Clinical results of an advanced SVT detection enhancement algorithm.

Introduction: Supraventricular tachycardia (SVT) has many characteristics that are similar to ventricular tachycardia (VT). This presents a significant challenge for the SVT-detection algorithms of an implantable cardioverter defibrillator (ICD). A newly developed ICD, which utilizes a Vector Timing and Correlation algorithm as well as interval-based conventional SVT discrimination algorithms (Rhythm ID), was evaluated in this study.

Long-term retention of cardiac resynchronization therapy.

Objectives: The purpose of this study was to determine the frequency and causes of intermittent and permanent loss of cardiac resynchronization therapy (CRT) in patients who have undergone the successful implantation of a transvenous defibrillator that delivers CRT (CRT-D).

Background: The causes of loss of CRT have not been described.

Methods: The records of 512 patients who underwent an attempt at implantation of a transvenous CRT-D device as part of the VENTAK CHF/CONTAK CD Biventricular Pacing study were analyzed.

Magnetic resonance imaging and cardiac pacemaker safety at 1.5-Tesla.

Objectives: The study was done to determine whether patients with pacemakers could safely undergo magnetic resonance imaging (MRI) at 1.5-Tesla (T).

Background: Because of theoretical risks, it is an absolute contraindication for a patient with a pacemaker to undergo MRI.