TY - JOUR
T1 - Left ventricular energetics in closed-chest dogs
AU - Prabhu, S. D.
AU - Freeman, G. L.
PY - 1993
Y1 - 1993
N2 - Studies of ventricular energetics using the relation between myocardial O2 consumption (MV̇O2) and pressure-volume area (PVA) have been performed extensively in the isolated heart, but not in the intact animal. We characterized the MV̇O2-PVA relation and its response to heart rate (HR) in eight closed-chest dogs instrumented with high-fidelity micromanometers, piezoelectric crystals, coronary flow probes, and coronary sinus oximetric catheters. The effect of dobutamine was studied in five dogs. MV̇O2 is linearly related to PVA with lower MV̇O2 required for the generation of smaller PVAs. Baseline contractile efficiency (EFF) was 25.6 ± 2.8%. High pacing rates reduced EFF (25.7 ± 3.2% at a HR of 107 ± 3 beats/min vs. 16.3 ± 2.4% at a HR of 194 ± 5 beats/min, P < 0.0167) and load-independent MV̇O2 per beat (0.562 ± 0.119 vs. 0.377 ± 0.074 J · beat-1 · 100 g LV-1, P < 0.0167) while increasing end-systolic elastance (E(es)) (9.4 ± 1.3 vs. 18.6 ± 3.1 mmHg/ml, P < 0.0167). Dobutamine administration increased load-independent MV̇O2 per beat (0.392 ± 0.108 vs. 0.607 ± 0.083 J · beat-1 · 100 g LV-1, P < 0.05) and contractility (E(es) 10.1 ± 1.5 vs. 32.0 ± 7.6 mmHg/ml, P < 0.05) without changing EFF (28.8 ± 3.8 vs. 30.3 ± 3.8%, P = NS). Thus the intact animal displays loss of EFF at high heart rates but maintains EFF during dobutamine stimulation. Both interventions increased load-independent MV̇O2 per minute, indicating increased O2 requirements for excitation-contraction coupling.
AB - Studies of ventricular energetics using the relation between myocardial O2 consumption (MV̇O2) and pressure-volume area (PVA) have been performed extensively in the isolated heart, but not in the intact animal. We characterized the MV̇O2-PVA relation and its response to heart rate (HR) in eight closed-chest dogs instrumented with high-fidelity micromanometers, piezoelectric crystals, coronary flow probes, and coronary sinus oximetric catheters. The effect of dobutamine was studied in five dogs. MV̇O2 is linearly related to PVA with lower MV̇O2 required for the generation of smaller PVAs. Baseline contractile efficiency (EFF) was 25.6 ± 2.8%. High pacing rates reduced EFF (25.7 ± 3.2% at a HR of 107 ± 3 beats/min vs. 16.3 ± 2.4% at a HR of 194 ± 5 beats/min, P < 0.0167) and load-independent MV̇O2 per beat (0.562 ± 0.119 vs. 0.377 ± 0.074 J · beat-1 · 100 g LV-1, P < 0.0167) while increasing end-systolic elastance (E(es)) (9.4 ± 1.3 vs. 18.6 ± 3.1 mmHg/ml, P < 0.0167). Dobutamine administration increased load-independent MV̇O2 per beat (0.392 ± 0.108 vs. 0.607 ± 0.083 J · beat-1 · 100 g LV-1, P < 0.05) and contractility (E(es) 10.1 ± 1.5 vs. 32.0 ± 7.6 mmHg/ml, P < 0.05) without changing EFF (28.8 ± 3.8 vs. 30.3 ± 3.8%, P = NS). Thus the intact animal displays loss of EFF at high heart rates but maintains EFF during dobutamine stimulation. Both interventions increased load-independent MV̇O2 per minute, indicating increased O2 requirements for excitation-contraction coupling.
KW - contractility
KW - myocardial mechanics
KW - oxygen consumption
UR - http://www.scopus.com/inward/record.url?scp=0027378255&partnerID=8YFLogxK
U2 - 10.1152/ajpheart.1993.265.4.h1048
DO - 10.1152/ajpheart.1993.265.4.h1048
M3 - Article
C2 - 8238392
AN - SCOPUS:0027378255
SN - 0002-9513
VL - 265
SP - H1048-H1055
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 4 34-4
ER -