Abstract 18440: Left Ventricular Epicardial Pacing Reduces Intramural Dyssynchrony in Myopathic Human Hearts: Implications for Biventricular Pacing
Introduction: Intramural electrical activation during pacing has not been well-defined in human myopathic hearts. The aim of this study was to characterize the electrical activation patterns in human myopathic hearts during RV endocardial (RVEndoP) and LV epicardial (LVEpiP) pacing. We hypothesized that (1) compared to RVEndoP, LVEpiP would produce less electrical intramural activation delay and (2) LVEpiP activates the diseased myocardium through the ventricular endocardium and therefore the transmural activation sequence is from the endocardium to the epicardium.
Methods: Explanted hearts from 7 patients (5 male, 46±10 yrs) who underwent transplantation were Langendorff-perfused and mapped using an epicardial sock electrode array (112 electrodes) and 25 intramural plunge needles (4 electrodes, 2 mm spacing), for a total of 100 unipolar intramural electrodes. Electrograms were recorded during LV epicardial and RV endocardial pacing. The maximal negative dV/dt of the unipolar electrograms was used to define local activation time. The mean LV activation time was defined as the mean activation times of the LV plunge needle electrodes. Activation patterns along the intramural needles were analyzed for the earliest activating layers.
Results: The mean LV activation time was significantly shorter with LVEpiP than with RVEndoP (125 ± 44 ms vs. 172 ± 43 ms, p<0.0001), with significantly earlier activation of the lateral freewall. Both LVEpiP and RVEndoP resulted in the endocardial layer being activated earliest (49% ± 6% vs. 59% ± 4%), as compared with other intramural layers (p<0.0001).
Conclusion: In myopathic human hearts, LVEpiP resulted in less LV intramural activation delay and therefore, less intramural LV dyssynchrony, compared to RVEndoP. LVEpiP also led to early activation of the endocardium in a significant proportion of the left ventricle, revealing the importance of the endocardium even when pacing from the epicardium.
- Bi-ventricular pacing
- Resynchronization therapy
- Advancing heart failure
- Intraventrocular dysshynchrony
- © 2010 by American Heart Association, Inc.