Randomized controlled trial comparing simultaneous versus optimized sequential interventricular stimulation during cardiac resynchronization therapy.

Background: Cardiac resynchronization therapy (CRT) reduces morbidity and mortality and improves symptoms in patients with systolic heart failure (HF) and ventricular dyssynchrony. This randomized, double-blind, controlled study evaluated whether optimizing the interventricular stimulating interval (V-V) to sequentially activate the ventricles is clinically better than simultaneous V-V stimulation during CRT.

Methods: Patients with New York Heart Association (NYHA) III or IV HF, meeting both CRT and implantable cardioverter-defibrillator indications, randomly received either simultaneous CRT or CRT with optimized V-V settings for 6 months.

Shorter AV delays provide improved echocardiographic hemodynamics during exercise in patients receiving cardiac resynchronization therapy.

Background: Although atrial ventricular (AV) intervals are often optimized at rest in patients receiving cardiac resynchronization therapy (CRT), there are limited data on the impact of exercise on optimal AV interval.

Methods: In 15 patients with CRT, AV intervals were serially programmed while patients were supine and at rest, and during exercise with heart rates that averaged 20 and 40 beats per minute above their resting rates. Echocardiographic Doppler images were acquired at each programmed AV interval and each rate.

Sustained reverse left ventricular structural remodeling with cardiac resynchronization at one year is a function of etiology: quantitative Doppler echocardiographic evidence from the Multicenter InSync Randomized Clinical Evaluation (MIRACLE).

Background: Cardiac resynchronization therapy (CRT) is an effective therapy for patients with moderate to severe heart failure and prolonged QRS duration. The purpose of this study was to determine whether reverse left ventricular (LV) remodeling and symptomatic benefit from CRT were sustained at 12 months, and if so, in what proportion of patients this occurred.

Methods And Results: Serial Doppler echocardiograms were obtained at baseline and 6 and 12 months after CRT in 228 patients enrolled in the Multicenter InSync Randomized Clinical Evaluation (MIRACLE) trial.

Evaluation of ventricular synchrony using novel Doppler echocardiographic indices in patients with heart failure receiving cardiac resynchronization therapy.

Cardiac resynchronization therapy improves hemodynamics in selected patients with heart failure. Mechanic asynchrony parameters that may guide patient selection or therapy optimization are still being investigated. A biventricular (BiV) pacemaker was implanted in 34 patients with dilated ischemic, idiopathic, or valvular cardiomyopathy, and a QRS duration of > or =130 milliseconds.

Noninvasive assessment of cardiac resynchronization therapy for congestive heart failure using myocardial strain and left ventricular peak power as parameters of myocardial synchrony and function.

Introduction: Although invasive studies have shown that cardiac resynchronization therapy by biventricular pacing improves left ventricular (LV) function in selected heart failure patients, it is impractical to apply such techniques in the clinical setting. The aim of this study was to assess the acute effects of cardiac resynchronization therapy by noninvasive techniques.

Methods And Results: Twenty-two patients enrolled in the InSync trial (age 64 +/- 9 years, 18 men and 4 women; all with ejection fraction < 35% and QRS > 130 msec) were studied 1 to 12 months after pacemaker implantation during pacing, and while ventricular pacing was inhibited.

Isolated four-chamber working swine heart model.

Background: Isolated heart models separate cardiac characteristics from systemic characteristics with subsequent findings used in cardiac research, including responses to pharmacologic, mechanical, and electrical components. The model objective was to develop the ability to represent in situ physiologic cardiac function ex vivo.

Methods: Swine hearts were chosen over rat or guinea pig models due to their notably greater anatomical and physiologic similarities to humans.