From the Cardiac Rhythm Management Laboratory, Division of Cardiovascular
Diseases, Department of Medicine (R.G.W., G.P.W., D.L.R., W.M.S., R.E.I.),
Department of Physiology and Biophysics (N.C.), and Department of Biomedical
Engineering (J.M.R.), University of Alabama at Birmingham; and Department of
Therapy Research, CPI, St Paul, Minn, a Division of Guidant Corp (B.H.K.).
Correspondence to Raymond E. Ideker, MD, PhD, Cardiac Rhythm Management Laboratory, 1670 University Blvd, Volker Hall, B140, Birmingham, AL 35294-0019. E-mail rei{at}crml.uab.edu
BackgroundElectrical mapping
studies indicate an interval of 40 to 100 ms between a defibrillation
shock and the earliest activation that propagates globally over the
ventricles (globally propagated activation, GPA). This study determined
whether activation occurs during this interval but propagates only
locally before being blocked (locally propagated activation,
LPA).
Methods and ResultsIn five anesthetized pigs, the heart
was exposed and a 504-electrode sock with 4-mm interelectrode spacing
was pulled over the ventricles. Ten biphasic shocks of a strength near
the defibrillation threshold (DFT) were delivered via intracardiac
catheter electrodes, and epicardial activation sequences were mapped
before and after attempted defibrillation. Local activation was defined
as dV/dt
ConclusionsLPAs exist after successful and failed shocks near
the DFT. Thus, the time from the shock to the GPA is not totally
electrically silent.
© 1998 American Heart Association, Inc.
Basic Science Reports
Locally Propagated Activation Immediately After Internal Defibrillation
-0.5 V/s. Postshock activation times and wave-front
interaction patterns were determined with an animated display of dV/dt
at each electrode in a computer representation of the
ventricular epicardium. LPAs were observed after 40 of the
50 shocks. A total of 173 LPA regions were observed, each of which
involved 2±2 (mean±SD) electrodes. LPAs were observed after both
successful and failed shocks but occurred earlier
(P<.0001) after failed (35±8 ms) than successful
(41±16 ms) shocks, although the times at which the GPA appeared were
not significantly different. On reaching the LPA region, the GPA front
either propagated through it (n=135) or was blocked (n=38). The time
from the onset of the LPA until the GPA front propagated to reach the
LPA region was shorter (P<.01) when the GPA front was
blocked (32±12 ms) than when it propagated through the LPA region
(63±20 ms).
Key Words: defibrillation mapping waves
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