Clonidine for major vascular surgery in hypertensive patients: a double-blind, controlled, randomized study.

The utility of clonidine for hypertensive patients presenting for major vascular procedures remains debatable. Twenty-one hypertensive patients presenting for aortic surgery were given clonidine (n = 11) or placebo (n = 10) in a double-blind, randomized manner. Clonidine was administered 6 micrograms/kg per os 120 min before induction of anesthesia and 3 micrograms/kg intravenously (i.v.) over 60 min from aortic declamping to skin closure. Anesthesia was induced with alfentanil 20 micrograms/kg, midazolam, and atracurium and maintained with nitrous oxide 70%, an alfentanil infusion (0.25 microgram.kg-1. min-1), and isoflurane. Anesthetic requirements, circulatory variables, interventions, and isoproterenol dose-response curves (pre- and postoperatively) were determined. Plasma concentrations of clonidine, alfentanil, and vasoactive hormones were measured. When the clonidine group was compared with the placebo group, (a) isoflurane, alfentanil, and midazolam requirements were reduced by 38%, 42%, and 41%, respectively (P = 0.04, 0.03, 0.0002, respectively); (b) supplemental circulatory and anesthetic adjustments were reduced by 51% (P = 0.0006); (c) interventions with vasopressors were not significantly increased (placebo: two; clonidine: five); (d) systolic and mean arterial pressures and heart rate were reduced; (e) increases in norepinephrine, epinephrine, and plasma renin activity were suppressed, whereas vasopressin surge was attenuated; and (f) chronotropic response to isoproterenol was unaffected. Clonidine was effective in reducing anesthetic requirements and in improving circulatory stability in hypertensive patients presenting for major vascular procedures.

The embolic type of popliteal entrapment syndrome.

The authors describe their experience with two patients who presented with clinical extremes of popliteal entrapment syndrome. One patient presented with acute ischemia and the second patient presented with a chronic Buergerian-like syndrome. The common denominator for both of them was embolic phenomena originating at the site of entrapment. Discussion is centered on pathogenesis of the embolic phenomenon, prevalence of distal arterial degradation and its clinical manifestation. The clue for differentiation from true Buerger disease is the angiographic pattern demonstrating apparently healthy distal arterial segments, confirmed by mandatory arterial biopsy. It is emphasized that in cases having acute embolic presentation the primary pathology should be treated concomitantly to revascularization.

Extracorporeal repair of renal artery branch lesions.

Complex renal artery lesions which formerly would have been treated by nephrectomy may now be reconstructed by extracorporeal surgery and autotransplantation. Our experience in 15 patients (17 operations) with renal artery lesions extending into its branches or confined to them is described. Two patients underwent separate operations on both sides. The indications for surgery were severe renovascular hypertension (10 cases), renal artery aneurysm, (5 cases) and deteriorating renal function (2 cases). Overall clinical results after a mean follow up of 3 years were considered excellent in 13 procedures (11 patients). Improvement in 2 patients and failure in the other 2, who ultimately underwent nephrectomy. Discussion is focussed on results, vascular indications, (namely aneurysm, stenosis, dissecting aneurysm and trauma) and surgical techniques. Preservation of functioning renal tissue should be the ultimate goal of renovascular surgery where the ex vivo technique, when indicated, will achieve favorable results in most patients.