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Effects of Electrode‐Myocardial Separation on Cardiac Stimulation in Conductive Solution
Author(s) -
KNISLEY STEPHEN B.,
POLLARD ANDREW E.,
EAST VLADIMIR G.
Publication year - 2000
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/j.1540-8167.2000.tb01760.x
Subject(s) - endocardium , stimulation , optical mapping , medicine , electrode , defibrillation , biophysics , bidomain model , cardiology , electrophysiology , chemistry , neuroscience , biology
Electrode‐Myocardial Separation. Introduction. Effects of a conductive bath and electrodemyocardial separation on cardiac stimulation have not been elucidated. These factors may play a role in endocardial catheter stimulation or defibrillation. Methods and Results. We studied effects of a bath and separation on transmembrane voltage changes during stimulation (ΔVm) and excitation thresholds in rabbit hearts, cultured rat cardiac cell monolayers and cardiac bidomain computer models. Similar to previous epicardial measurements with no bath, a dogbone pattern of ΔVm during stimulation was found in bathed epicardium and right ventricular septal endocardium and in models of bathed anisotropic myocardium. Electrode‐myocardial separation altered spatial distributions of ΔVm, moved reversals of the sign of ΔVm farther from the stimulation epicenter, and decreased aspect ratio of ΔVm (i.e., length/width of dogbone contours of ΔVm). The separation increased thresholds and reduced maximal ΔVm, while ΔVm at sites away from maxima increased or decreased. Anodal thresholds in models initially were larger than those in experiments and decreased when models were altered to include nonuniform cellular coupling. Existence of nonuniformity in monolayers was indicated by irregular excitation patterns. Conclusion. Electrode‐myocardial separation alters spatial distributions of ΔVm, which may impact on arrhythmia induction by altering distributions of states of ΔVm‐sensitive ion channels. The results also indicate that excitation thresholds may depend on tissue nonuniformities. ( J Cardiovasc Electrophysiol, Vol. 11. pp. 1132‐1143, October 2000 )