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 (HTE A) treatment compared with the authors' previous studies, to test the hypot hesis that the mechanism by which HTEA reduces angina during longterm treat ment includes an improvement in myocardial blood flow distribution and a re duction in stress-induced ischemia, and to show that new myocardial infarct ions are not masked or missed in patients receiving HTEA. Design: Prospective consecutive study. Setting: Department of Veteran's Affairs medical center and university-affi liate 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 re solution of stress-induced ischemia at 8 and 12 months. The remaining 4 pat ients 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 te sts. 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 i n myocardial blood flow; rather the improvement in symptoms probably result s, in part, from an anesthetic effect. HTEA does not mask the development o f new myocardial infarctions. Copyright (C) 2000 by W.B, Saunders Company.