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Background: The design of pacemaker leads has continued to evolve; ease of lead handling, improved electrical performance, and magnetic resonance imaging (MRI) conditional aspects have become more important, while safety remains critical. The INGEVITY™ family leads was designed to provide MRI conditional aspects, decreased diameter, and improved performance of pacemaker leads. The INGEVITY study is an investigational device exemption trial evaluating the acute and chronic safety and effectiveness of these leads., Methods: Consecutive patients were included in 77 institutions worldwide, where 1,657 leads (846 right ventricular active fixation leads, 213 right ventricular passive fixation leads, 121 right atrial passive fixation preformed J-leads, and 477 right atrial active fixation leads) were implanted or attempted in 1,060 subjects., Results: At 3-month follow-up, the electrical performance were: mean pacing threshold 0.67 V at 0.5-ms pulse width, pacing impedance 773 ohms, mean P-wave amplitude 4.8 mV, and R-wave amplitude 16.5 ± 6.5 mV. Over a median follow-up of 31 months, 93 subjects died and 33 subjects reported lead-related complications. Lead-related complication-free rate from 0 to 3 months and 3 to 12 months for all leads was 98.4% and 99.7%, respectively. The hazard of lead-related complications was observed to be decelerating over the course of follow-up (Weibull shape = 0.23). The overall lead dislodgment rate observed in the study was 1.3%, the perforation rate was 0.0%, and the pericardial effusion rate was 0.3%., Conclusions: The clinical performance of the INGEVITY lead demonstrated a high lead-related complication-free rate over 12 months of follow-up and excellent electrical characteristics., (© 2017 Wiley Periodicals, Inc.)

Introduction: Automatic pacing threshold (AT) testing may simplify device follow-up and improve device longevity. This study's objective was to evaluate the performance of a left ventricular (LV) evoked response sensing-based AT algorithm, for cardiac resynchronization therapy (CRT) devices., Methods: Patients scheduled for CRT-D/P implant were enrolled. A manual step-down threshold test and a Left Ventricular Automatic Threshold (LVAT) test in each of four pacing vectors-LVTip→Can, LVTip→right ventricle (RV), = LVRing→Can, and LVRing→RV-were conducted. Patients were randomized to either 0.4-ms or 1.0-ms pacing pulse width and in the manual and LVAT test order. A blinded core lab electrophysiologist (EP) determined the threshold using the surface electrocardiogram (gold standard)., Results: Data from 70 patients were analyzed. Bipolar LV leads from three major manufacturers were used. A total of 273 AT tests were performed; 12 AT tests did not result in a threshold due to improper testing conditions. Of 261 eligible tests, 234 AT tests (89.6%) returned a threshold measurement. Of the 234 tests, in 233 tests (99.5%) the algorithm-determined threshold matched the EP-determined threshold for that test. A total of 16,689 capture and 526 noncapture beats were collected and the accuracy for detecting capture and noncapture were 98.5% and 99.7% with a two-sided 95% confidence level of (98.4%, 98.7%) and (99.4%, 100%), respectively. No AT threshold measurement was lower than the EP-determined threshold., Conclusion: In this study, the results suggest that the LVAT algorithm is accurate at determining pacing thresholds in multiple pacing configurations and a wide range of LV leads in CRT-D/P patients., (©2011, The Authors. Journal compilation ©2011 Wiley Periodicals, Inc.)

The purpose of this study was to develop a better understanding of the pacing and sensing characteristics of electrodes placed in the proximal cardiac veins. A detailed mapping of the coronary sinus (CS) and great cardiac vein (GCV) was done on 25 patients with normal sinus rhythm using a deflectable electrophysiological catheter. Intrinsic bipolar electrograms and atrial and ventricular pacing voltage thresholds were measured. For measurement purposes, the GCV and the CS were each subdivided into distal (D), middle (M), and proximal (P) regions, for a total of six test locations. Within the CS and GCV, the average atrial pacing threshold was always lower (P < 0.05) than the ventricle with an average ventricular to atrial ratio > 5, except for the GCV-D. The average atrial threshold in the CS and GCV ranged from 0.2- to 1.0-V higher than in the atrial appendage. Diaphragmatic pacing was observed in three patients. Atrial signal amplitude was greatest in the CS-M, CS-D, and GCV-P and smaller in the CS-P, GCV-M, and GCV-D. Electrode spacing did not significantly affect P wave amplitude, while narrower electrode spacing attenuated R wave amplitude. The average P:R ratio was highest with 5-mm-spaced electrodes compared to wider spaced pairs. The P:R ratio in the CS was higher (P < 0.05) than in all positions of the GVC. It is possible to pace the atrium independent of the ventricle at reasonably low thresholds and to detect atrial depolarization without undue cross-talk or noise using closely spaced bipolar electrode pairs. The areas of the proximal, middle, and distal CS produced the best combination of pacing and sensing parameters.

This report describes the cardiac conduction abnormalities, detected by invasive electrophysiological study, in two identical siblings with symptomatic congenital long QT syndrome. Both patients had evidence of intra-Hisian conduction delay in response to programmed atrial stimulation and pacing induced infranodal block was seen in one of the two patients. The response of the observed conduction delay to autonomic interventions is described. The observed electrophysiologic abnormalities are consistent with previously reported pathological findings and document the association of functional conduction system disease with congenital QT prolongation.