Preliminary report on high thoracic epidural analgesia: Relationship between its therapeutic effects and myocardial blood flow as assessed by stress thallium distribution

Objectives: To extend the duration of high thoracic epidural analgesia (HTEA) treatment compared with the authors' previous studies, to test the hypothesis that the mechanism by which HTEA reduces angina during longterm treatment includes an improvement in myocardial blood flow distribution and a reduction in stress-induced ischemia, and to show that new myocardial infarctions are not masked or missed in patients receiving HTEA. Design: Prospective consecutive study. Setting: Department of Veteran's Affairs medical center and university-affiliate hospital, Participants: Six consenting adult patients. Interventions: Patients were evaluated before HTEA catheter insertion and >2 months after HTEA catheter insertion with stress thallium tests. Measurements and Main Results: Two of 6 patients had improvement but not resolution of stress-induced ischemia at 8 and 12 months. The remaining 4 patients had no change in stress-induced ischemia. None of the 6 patients had any new areas of ischemia or infarction as determined by stress thallium tests. Conclusions: The authors previously showed that HTEA is safe and effective in relieving refractory angina pectoris. The current study shows that this therapeutic effect persists and does not appear to be related to a change in myocardial blood flow; rather the improvement in symptoms probably results, in part, from an anesthetic effect. HTEA does not mask the development of new myocardial infarctions. Copyright (C) 2000 by W.B, Saunders Company.