ABSTRACT
Aims Cardiac resynchronization therapy with biventricular pacing has proved beneficial in symptomatic heart failure patients, yet the effects in patients with structurally normal hearts remain unknown. We hypothesized that, in an acute swine model with normal anatomy and function, single-site right ventricular (RV) pacing would better preserve haemodynamic function and electrical activation compared to biventricular pacing. Methods Endocardial single-site pacing was performed in anesthetized swine (n = 7) from the RV septum and RV apex. Biventricular pacing was performed using an epicardial left ventricular (LV) lead and a RV lead. High-resolution, non-contact mapping was employed to record LV activation sequences simultaneously with haemodynamic data after 5 min of consistent capture. Results All pacing interventions significantly prolonged QRS and total endocardial activation durations (P < 0.05) compared to intrinsic activation. Biventricular pacing with the RV apex lead significantly impaired LV systolic mechanics (dP/dt(max), max LV pressure; P < 0.05), and reduced LV relaxation to the greatest extent (dP/dt(min), P = ns). Right ventricular septal pacing conserved function better than other pacing interventions (P = ns) and elicited an intrinsic electrical activation sequence. Conclusion In intact, synchronous hearts, acute biventricular pacing resulted in systolic dysfunction and abnormal LV electrical activation.
Subject(s)
Cardiac Pacing, Artificial/methods , Heart Ventricles/physiopathology , Animals , Cardiac Pacing, Artificial/adverse effects , Electric Stimulation , Electrocardiography , Electrophysiologic Techniques, Cardiac , Heart Conduction System/physiopathology , Heart Ventricles/innervation , Models, Animal , Swine , Ventricular Dysfunction, Left/etiology , Ventricular Dysfunction, Left/physiopathologyABSTRACT
The laser sheath uses optical fibers, delivering pulsed ultraviolet excimer laser light, to vaporize fibrotic tissue binding intravenous cardiac leads to the vein or heart wall during lead extraction from the implant vein. The total investigational experience with laser sheaths is reported. During the period from October 1995 to December 1999, 2,561 pacing and defibrillator leads were treated in 1,684 patients at 89 sites in the United States with three sizes of laser sheath. Endpoints were complete removal of the lead, partial removal (leaving the tip behind), or failure (abandoning the lead, onset of complications, change to transfemoral or transatrial approach). Minimal follow-up at 30 days was recorded. Of the leads, 90% were completely removed, 3% were partially removed, and the balance were failures. Major perioperative complications (tamponade, hemothorax, pulmonary embolism, lead migration, and death) were observed in 1.9% of patients with in hospital death in 13 (0.8%). Minor complications were seen in an additional 1.4% of patients. Multivariate analysis showed that implant duration was the only preoperative independent predictor of failure; female sex was the only multivariate predictor of complications. Success and complications were not dependent on laser sheath size. At follow-up, various extraction related complications were observed in 2% of patients. The learning curve showed a trend toward fewer complications with experience. Lead extraction with the laser sheath can be safely practiced with high success rates. Success is independent of laser sheath size. Major complications can be expected in < 2% of patients, and occur more often during an investigator's early experience.
