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Excitation of the Intrinsic Conduction System Through His and Interventricular Septal Pacing
Author(s) -
LASKE TIMOTHY G,
SKADSBERG NICHOLAS D,
HILL ALEXANDER J,
KLEIN GEORGE J,
IAIZZO PAUL A
Publication year - 2006
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.2006.00360.x
Subject(s) - medicine , coronary sinus , interventricular septum , cardiology , cardiac pacing , bundle of his , electrode , ventricular pacing , electrical conduction system of the heart , electrocardiography , ventricle , heart failure , chemistry
Background: Direct His bundle pacing results in rapid synchronous ventricular activation. However, clinical experiences with such pacing have been associated with long procedure times and compromised pacing and sensing performance.Methods: We evaluated myocardial activation sequences (AS) for pacing of the His bundle and peri‐His region and assessed acute pacing performance using custom‐designed plunge electrodes. Unipolar pacing was performed in isolated swine hearts (n = 10) using four quadripolar stimulation/sensing electrodes implanted into the interventricular septum and equally spaced between the membranous septum and the coronary sinus ostium (zones 1–4, respectively; electrode depth (ED) 1 = most distal, ED 4 = most proximal). Optimal pacing sites were defined as: pacing thresholds ≤1.5 V, a P‐R ratio of ≤0.5, and ≥50% occurrence of an intrinsic midseptal left ventricular (LV) endocardial electrical breakout (BO) and activation pattern.Results: Pacing thresholds improved with greater depth of electrode location within the septum (ED 1: 1.51 ± 0.8 V vs ED 4: 5.2 ± 3.8 V, P < 0.001), as did the P‐R ratio (0.34 ± 0.6 vs 0.78 ± 1.0, P < 0.05). His potentials were only observed in zone 1 and 2 electrodes (0.12 and 0.02 mV, respectively). Only electrodes in zones 1 and 2 produced LV endocardial electrical BOs in the midseptal region that demonstrated an intrinsic‐like endocardial AS. Depth 1 and 2 electrodes (11.75 and 8.75 mm, respectively) in zone 1 satisfied all three optimal pacing site requirements.Conclusions: This study has shown that LV activation patterns similar to sinus rhythm may be achieved without direct activation of the His bundle, while maintaining acceptable pacing and sensing performance. These data indicate that pacing systems designed to stimulate the tissues below the point at which the His bundle penetrates the central fibrous body may provide improved system efficiency and LV performance in comparison to both direct His bundle pacing and traditional pacing sites.