Lymphatic diversion prevents myocardial edema following mesenteric ischemia/reperfusion.
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OBJECTIVE: Mesenteric ischemia/reperfusion (I/R) is associated with cardiac dysfunction. Mesenteric lymph primes polymorphonuclear leukocytes (PMNs) for increased superoxide release following I/R. We hypothesized that mesenteric I/R causes myocardial edema resulting in myocardial dysfunction, and that diverting mesenteric lymph would preserve myocardial function. METHODS: Two canine groups were studied: lymphatic diversion (LD) and no lymphatic diversion (No LD). Preload recruitable stroke work, +/-dp/dt(max), isovolumic relaxation (tau), cardiac output, and myocardial water content (MWC) were determined. I/R consisted of 60 min of ischemia followed by 180 min of reperfusion. Myocardial myeloperoxidase (MPO) was measured as an index of PMN leukosequestration. In addition, mesenteric lymph harvested after I/R was infused into normal canines and all variables measured. RESULTS: MWC increased from baseline in No LD. Tau and -dp/dt(max) were significantly affected in No LD, but not in LD. After mesenteric I/R, mesenteric lymph primed PMNs for increased superoxide production. Lymph diversion resulted in significantly lower myocardial MPO. With reinfusion of I/R lymph, MWC and tau increased. MPO was also increased post I/R mesenteric lymph reinfusion. CONCLUSIONS: Our data indicate that myocardial dysfunction after mesenteric I/R is due to lymph-induced, PMN-mediated microvascular alterations and myocardial edema.
