Central neuroaxis blockade and coronary circulation.

The coronary circulation is subject to modulation by the autonomic nervous system. Thus, sympathetic stimulation causes coronary vasodilation in healthy humans, whereas stenotic coronary arteries react by vasoconstriction in response to sympathetic stimulation. It is for this reason that experimental studies and clinical evidence revealed beneficial effects of a blockade of cardiac sympathetic drive by thoracic epidural anaesthesia on coronary perfusion and myocardial function in normal and in ischaemic myocardium. In contrast, segmental lumbar epidural anaesthesia leads to a compensatory increase in cardiac sympathetic outflow which may jeopardize myocardial areas dependent on perfusion by stenotic coronary arteries.