[The effects cervicothoracic sympathetic blockade on left ventricular function].

Abstract

OBJECTIVE: Cervicothoracic sympathetic blocks (stellate ganglion blocks) not only influence pain, but also lead to regional sympathetic denervation of part of the left ventricular wall, while other ventricular regions stay under the control of the unblocked side. What is the influence of these imbalances of sympathetic innervation on ventricular function? METHODS: Thirteen anaesthetised dogs were instrumented for measurement of left ventricular pressure (tip-manometer), cardiac output (ultrasonic flow probe) and regional myocardial function (sonomicrometry) in two left ventricular regions, innervated by the left or right sympathetic system, respectively. Electrical stimulations of the left and right stellate ganglia, and left and right sided stellate ganglion blocks were performed. In eight patients with no cardiac disease, the effects of left stellate ganglion blocks on echocardiographic variables of ventricular function were investigated. RESULTS: In dogs, the unilateral ganglion stimulations led to an increase in regional and global contractility. However, left ventricular wall motion became asynchronous and, despite an increase in contractility, relaxation was impaired. After the ganglion blocks, there was a decrease in regional contractility within the denervated area, also leading to an asynchronous wall motion. As a consequence, relaxation was impaired, but cardiac output was maintained. In the patients, there was an increase in isovolumic relaxation time. This change was also within the compensatory range and cardiac output increased slightly as a consequence of a simultaneous afterload reduction by the ganglion block. CONCLUSION: The studies show a disturbance of diastolic function after stellate ganglion blocks, resulting from an asynchronous wall motion pattern after the regional denervation. However, the changes were within the compensatory range of a healthy ventricle and cardiac output was not reduced.