Effects of arterial distensibility on left ventricular ejection in the depressed contractile state.
OBJECTIVE
The aim was to evaluate the effects of arterial distensibility on ventricular ejection in various ventricular contractile states: (1) control; (2) a regionally depressed contractile state due to left circumflex coronary artery occlusion (ligation); (3) a globally depressed contractile state induced by lignocaine (lignocaine); and (4) a globally augmented contractile state due to dobutamine infusion (dobutamine).


METHODS
Arterial compliance was decreased from 2.3 x 10(-4) dyne-1.cm5 (C2.3) to 0.4 x 10(-4) dyne-1.cm5 (C0.4), maintaining other afterload components and left ventricular end diastolic pressure constant. Nine excised perfused and paced canine hearts, supported from donor dogs, were used.


RESULTS
In control, ligation, lignocaine, and dobutamine groups, the difference in cardiac output between the compliance values of C0.4 and C2.3 was 124(SEM 32), 204(36), 163(33), and 130(24) ml, respectively. Thus cardiac output at C0.4, as a percentage of that at C2.3, was 88(2.8)% (control), 75(2.9)% (ligation), 82(2.9)% (lignocaine), and 88(2.4)% (dobutamine), respectively: control v ligation, and lignocaine v ligation, p < 0.001; control v lignocaine, and dobutamine v ligation, p < 0.01. Stroke work at C0.4 decreased in the ligation group (63%, p < 0.001) and in the lignocaine group (70%, p < 0.001).


CONCLUSIONS
When cardiac dysfunction is already present, decreased arterial distensibility has a further deleterious effect on cardiac output. This may be due to the fact that the pressure at the end of ejection is higher and as a result the change in dimension during ejection is considerably reduced, especially in cases with depressed cardiac function caused by afterload dependency.
Maruyama
Y
Y
First Department of Internal Medicine, Fukushima Medical College, Japan.
Nishioka
O
O
Nozaki
E
E
Kinoshita
H
H
Kyono
H
H
Koiwa
Y
Y
Takishima
T
T
D000818:Animals; D001157:Arterial Occlusive Diseases / Q000503:physiopathology; D001158:Arteries / Q000502:physiology*; D003187:Compliance; D003327:Coronary Disease / Q000503:physiopathology; D004280:Dobutamine / Q000494:pharmacology; D004285:Dogs; D008012:Lidocaine / Q000494:pharmacology; D009200:Myocardial Contraction / Q000502:physiology*; D009924:Organ Culture Techniques; D013318:Stroke Volume / Q000187:drug effects / Q000502:physiology*
D004280:Dobutamine; D008012:Lidocaine