POSTOPERATIVE REDUCTION OF HIGH SERUM-CHOLESTEROL CONCENTRATIONS AND EXPERIMENTAL VEIN BYPASS GRAFTS - EFFECT ON THE DEVELOPMENT OF INTERNAL HYPERPLASIA AND ABNORMAL VASOMOTOR FUNCTION
Ml. Klyachkin et al., POSTOPERATIVE REDUCTION OF HIGH SERUM-CHOLESTEROL CONCENTRATIONS AND EXPERIMENTAL VEIN BYPASS GRAFTS - EFFECT ON THE DEVELOPMENT OF INTERNAL HYPERPLASIA AND ABNORMAL VASOMOTOR FUNCTION, Journal of thoracic and cardiovascular surgery, 108(3), 1994, pp. 556-566
Hypercholesterolemia is an important contributor to the development of
intimal hyperplasia and superimposed accelerated atherosclerosis in v
ein bypass grafts. This study examines the effect of dietary modificat
ion of serum cholesterol on the development of intimal hyperplasia and
vasomotor function of vein grafts. Thirty male New Zealand White rabb
its had a right carotid vein bypass graft and were put to death 28 day
s after the operation. Twenty animals received a 1% cholesterol diet f
or 4 weeks before the operation. In 10 animals this diet was continued
until harvest (hypercholesterolemia group). In another 10 animals the
diet was changed to standard rabbit chow on the day of the surgical p
rocedure and continued until harvest (cholesterol reduction group). Th
e last 10 animals were control subjects. Vein grafts were harvested ei
ther for histologic study or for in vitro isometric tension studies. C
umulative dose response curves to norepinephrine, serotonin, bradykini
n, and endothelin-1 were determined. After in situ pressure fixation,
intimal thicknesses of the vein grafts were measured by videomorphomet
ry. The change in diet produced a 74% reduction in serum cholesterol c
oncentration within 28 days. There was a 26% reduction in the intimal
thickness of vein graft intimal hyperplasia and the macroscopic disapp
earance of atheromatous lesions from the graft wall, which are always
observed in vein grafts from the hypercholesterolemia group. Cholester
ol reduction did not change hypercholesterolemia-induced agonist super
sensitivity. Therefore, cholesterol reduction slows the formation of i
ntimal hyperplasia in vein grafts but does not prevent the persistence
of the hypercholesterolemia-associated smooth muscle phenotype.