Burn-induced organ dysfunction: vagus nerve stimulation improves cardiac function

Many studies have demonstrated the existence of an anti-inflammatory, parasympathetic pathway, termed as the inflammatory reflex. Burn-induced heart failure has been investigated in many previous studies. Proinflammatory cytokines, such as TNF-alpha, IL-1beta, and IL-6, have been shown to play a key pathogenetic role and vagus nerve stimulation attenuates proinflammatory cytokine production. This study was designed to evaluate postburn alterations of cardiac functional parameters after vagal electrostimulation.

A 30% total body surface area standardized, full-thickness rat burn model was used. Electric stimulation of the vagus nerve was performed. The following functional cardiac parameters were measured by ventricular microcatheterization: Maximal and minimal left ventricular pressure, mean left ventricular pressure, end-diastolic pressure (EDP), positive and negative pressure rise and fall (+/-dP/dt), cardiac contractility index, and assessment of the heart rate.

Vagus nerve stimulation improved maximal and minimal left ventricular pressure values compared with burn-only animals. End-diastolic pressure was elevated significantly in stimulated animals; however, EDP values were comparable with those in sham-injured animals. Analyzing positive and negative pressure development, +/-dP/dt was restored to levels measured in sham-injured animals but not to control animal levels. No variations in heart rate were found.

We as well as others have shown that inflammation after burn injury is a key pathogenetic element, and this study provides new evidence that cardiac function is also improved by vagus nerve stimulation. These results lead us to consider novel therapeutic options for the treatment of postburn cardiac dysfunction.