Left Ventricular Global and Regional Function during Lumbar Epidural Anesthesia in Patients With and Without Angina Pectoris. Influence of Volume Loading

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Abstract
The influence of lumbar epidural anesthesia without cardiac sympathectomy on global and regional left ventricular function was investigated prior to surgery in eight normal subjects (groups 1) and in ten patients suffering from stable mild effort-related angina (group 2). In both groups, epidural blockade was performed with 10 ml 0.5% plain bupivacaine. To differentiate the effects due to epidural blockade from those related to volume expansion, three sets of measurements were obtained: control, epidural blockade without volume loading, and epidural blockade with volume loading (500 ml lactated Ringer''s solution). Radionuclide angiography was used to determine cardiac output, left ventricular ejection fraction, end systolic and end diastolic volumes, and to analyse left ventricular wall motion. Peak systolic pressure-end systolic volume ratio was used as an index of myocardial contractility. Seventy-two hours postoperatively, a thallium 201 myocardial scintigraphy obtained after iv dipyridamole detected myocardial defects in all patients with a history of angina. These defects were fully redistributed in eight out of ten patients. Throughout the procedure, patients with a history of angina exhibited neither chest pain nor ECG evidence of myocardial ischemia. At control, left ventricular ejection fraction (LVEF) and systolic pressure-volume ratio (SPVR) were lower in group 2 than in group 1 (LVEF: 0.54 .+-. 0.02 vs. 0.64 .+-. 0.02, P .+-. 0.01), (SPVR: 2.3 .+-. 0.2 vs. 3.3 .+-. 0.4 mmHg/ml, P < 0.05). In addition, 19 hypokinetic sectors were found in group 2. In these patients, epidural blockade before volume loading induced a slight but significant improvement in left ventricular ejection fraction (0.59 .+-. 0.03, P < 0.01) and in regional wall motion (five hypokinetic sectors, P < 0.01). No change in these parameters was observed in normal patients. In both groups, myocardial contractility estimated by systolic pressure volume ratio was not altered during epidural blockade. After volume loading, in group 2, left ventricular ejection fraction returned to basal value, and a reduced wall motion was seen in 11 sectors. This study indicates that, in patients with stable mild effort-related angina, decrease in left ventricular loading induced by lumbar epidural anesthesia may improve left ventricular global and regional function as long as volume loading is limited.