TY - JOUR
T1 - Optimization of pacing parameters for conditioned latissimus dorsi muscle in cardiomyoplasty
AU - Davies, Charles R.
AU - Novoa, Roberto M.
AU - Jacobs, Gordon B.
AU - Irie, Hiroyuki
AU - Chen, Ji Feng
AU - Cosgrove, Delos M.
PY - 1991/7
Y1 - 1991/7
N2 - Synchronous paced contractions of latissimus dorsi muscle pedicle (LDM) around the heart improve ventricular function in dynamic cardiomyoplasty. To optimize assistance and prolong pacemaker battery life, the LDM should be stimulated with the lowest energy pacing parameters (PP) that will produce maximal muscle contraction. Muscle fractional shortening (FS) and duration of contraction (CT) were studied in conditioned, fatigue-resistant LDM of six goats. Fractional shortening and CT were determined at increasing amplitude, (A, 1-6v); pulse width, (PW, 60-450μsec); and frequency, (F, 5-130 Hz). Maximal rate of contraction was determined by pacing at higher rates. Maximal FS plateaued after V, 2.4 ± .6v; PW, 125 ± 47 μsec; and F, 36 ± 9 Hz. Mean CT for all PP was significantly longer (p ≤ 0.001) than the burst length (185 msec). Increasing F resulted in CT, which peaked at 460 ± 59 msec. Increasing rate of contraction demonstrated that over 87 beats per minute the muscle fails to achieve complete relaxation, and, therefore, maximal FS.
AB - Synchronous paced contractions of latissimus dorsi muscle pedicle (LDM) around the heart improve ventricular function in dynamic cardiomyoplasty. To optimize assistance and prolong pacemaker battery life, the LDM should be stimulated with the lowest energy pacing parameters (PP) that will produce maximal muscle contraction. Muscle fractional shortening (FS) and duration of contraction (CT) were studied in conditioned, fatigue-resistant LDM of six goats. Fractional shortening and CT were determined at increasing amplitude, (A, 1-6v); pulse width, (PW, 60-450μsec); and frequency, (F, 5-130 Hz). Maximal rate of contraction was determined by pacing at higher rates. Maximal FS plateaued after V, 2.4 ± .6v; PW, 125 ± 47 μsec; and F, 36 ± 9 Hz. Mean CT for all PP was significantly longer (p ≤ 0.001) than the burst length (185 msec). Increasing F resulted in CT, which peaked at 460 ± 59 msec. Increasing rate of contraction demonstrated that over 87 beats per minute the muscle fails to achieve complete relaxation, and, therefore, maximal FS.
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M3 - Conference article
C2 - 1751092
AN - SCOPUS:0026185086
VL - 37
SP - M163-M164
JO - ASAIO Journal
JF - ASAIO Journal
SN - 1058-2916
IS - 3
ER -