EFFECT OF ACUTE CARDIAC LYMPH STASIS ON METABOLIC CORONARY ADAPTATION IN THE DOG

Abstract

Surgical blockade of cardiac lymph drainage was
performed in dogs to examine the effect of acute cardiac
lymph stasis on coronary adaptive mechanisms.
Coronary blood flow (CBF) was measured using an
electromagnetic flow probe on the left anterior
descending (LAD) artery. Metabolic autoregulatory
capacity was assessed by eliciting reactive hyperemic
responses after flow interruptions of I 0-60 second
duration and by administering submaximal doses
(250-500 microgram) of adenosine, the putative transmitter of
reactive hyperemia, into the left heart. The effect of
lymph stasis was tested in two experimental groups,
one hour and 48 hours after lymph obstruction and
the data compared to control dogs.
Although cardiac lymph stasis did not notably
affect baseline arterial pressure and CBF, both reactive
hyperemic response and adenosine-induced coronary
vasodilation were reduced significantly (equal
to or less than 50% control). On occasion, a complete
absence of autoregulation was observed. These
findings suggest that cardiac lymph stasis decreases
vascular responsiveness to physiologic vasodilator
stimuli and/or retards diffusion of biologically
unstable substance(s) presumably involved in
autoregulation. Persistently impaired coronary
autoregulation in the lymphedematous heart may
contribute to progressive ischemic damage as for example
after myocardial infarction.