Assessment of the Extravascular Implantable Defibrillator: Feasibility of Substernal Ventricular Pacing

• Published in: Journal of cardiovascular electrophysiology 2017-06, Vol.28 (6), p.674-676
• Main Authors: BROUWER, TOM F., SMEDING, LONNEKE, BERGER, WOUTER R., DRIESSEN, ANTOINE H. G., GROOT, JORIS R., WILDE, ARTHUR A. M., KNOPS, REINOUD E.
• Format: Article
• Language: English
• Subjects: Aged; Arrhythmias, Cardiac - diagnosis; Arrhythmias, Cardiac - physiopathology; Arrhythmias, Cardiac - therapy; Cardiac Pacing, Artificial - adverse effects; Cardiac Pacing, Artificial - methods; Catheters; Defibrillators, Implantable; Electric Countershock - adverse effects; Electric Countershock - instrumentation; Electric Countershock - methods; Electrophysiologic Techniques, Cardiac; Feasibility Studies; Female; Heart Rate; Humans; ICD; implantable cardioverter‐defibrillator; Male; Materials Testing; Medical instruments; Middle Aged; Pacemaker, Artificial; pacing; Pericardium; Prospective Studies; Prosthesis Design; Pulse duration; Sternum; substernal; Thresholds; Time Factors; Treatment Outcome; Ventricle; Ventricular Function
• ISSN: 1045-3873; 1540-8167
• DOI: 10.1111/jce.13195

Substernal Pacing in Humans Introduction The objective of this study was to assess feasibility of ventricular pacing and thresholds from within the substernal space to examine a new extravascular ICD configuration with pacing capabilities. Methods In patients undergoing midline sternotomy, a duodecapolar diagnostic pacing catheter was positioned in the substernal space anterior to the pericardium, and a cutaneous patch in left lateral position. Different unipolar and bipolar pacing configurations were assessed. Strength‐duration curves were performed to identify the optimal output, starting at 25 mA with a pulse width of 10 milliseconds. Results Eight patients with mean age 69 ± 9 years were included. In 5, ventricular capture was achieved in ≥1 configuration. The mean bipolar pacing thresholds at PW 10, 5, 3, 1 milliseconds were 12.4 ± 3.7 mA (5 patients), 13.3 ± 5.8 mA (3 patients), 18.3 ± 5.7 mA (3 patients), and 25 ± 0 mA (2 patients), respectively. The 60‐mm electrode spacing was the most successful bipolar configuration. Unipolar pacing was successful in 3 out of 4 patients with mean thresholds of 10 ± 0 mA at 10 milliseconds (3 patients), 15 ± 0 mA at 5 milliseconds (3 patients), 16.7 ± 2.9 mA at 3 milliseconds (3 patients), and 20 ± 7.1 mA at 1 milliseconds (2 patients). Conclusion Ventricular pacing from the substernal space in patients with midline sternotomy is feasible. Closed sternum studies are needed to determine pacing thresholds more accurately.