Low mortality rates for elective surgical treatment of abdominal aortic aneurysms justify an aggressive approach in most patients. However, in high-risk patients with small aneurysms and no symptoms, the decision to operate remains a delicate balance of risk and benefit. Our observations include 99 high-risk patients with asymptomatic abdominal aortic aneurysms initially measuring 3 to 6 cm in the largest transverse diameter, who have been followed 1 to 9 years (average 2.4 years) with serial echographic measurements. Elective operations were performed for aneurysmal enlargement greater than 6 cm or symptom development. An additional 11 patients with aneurysms initially greater than 6 cm, whose initial evaluation did not result in elective surgery, were also followed. Serial data documented a mean expansion rate of 0.4 cm/year for aneurysms smaller than 6 cm. Forty-one of these 99 high-risk patients with small aneurysms eventually underwent an elective resection with two deaths (4.9%). Thirty-four patients (34%) died from causes unrelated to their unoperated aneurysms, and 21 patients (21%) are alive without symptoms. Three of the 99 patients suffered aneurysm rupture and emergency operation with two deaths. Thus, of the 99 high-risk patients with small aneurysms, four have died of elective aneurysm surgery or rupture (4%). A protocol of re-echo (or computerized tomography) examination at 3-month intervals appears to define which of these high-risk patients require elective aneurysm surgery, and has limited rupture to less than 5%. Improved criteria may emerge from recent advances in high-resolution computerized tomography.
Inferior vena caval obstruction is an unusual but important clinical problem for which adequate treatment previously has not been available. Recently, a polytetrafluoroethylene (PTFE) graft with external rigid spiral supports was developed that appeared particularly applicable to the venous system. In 18 dogs a 15 cm length of Impraflex was placed from the proximal right common iliac vein to the inferior vena cava (IVC) at the level of the renal veins after IVC and right iliac vein interruption. End-to-end and end-to-side iliac vein anastomoses were alternated, with and without distal femoral arteriovenous (AV) fistulas (AVFs). At 2 months, with a distal AV fistula, 11 of 12 (92%) grafts were patent, angiograms demonstrated no evidence of intraluminal clot, and there was no hind limb edema. Following AVF ligation 2 months after graft insertion, 10 grafts remained patent, but five developed some intraluminal thrombus and one of them progressed to complete occlusion. Four months after fistula ligation (6 months after graft insertion) 9 of 12 grafts (75%) remained patent. All six grafts without distal AVF were occluded within 1 week. This procedure was performed on one severely symptomatic patient who had IVC occlusion, and currently the patient shows marked improvement. Thus IVC bypass is possible when an externally supported PTFE prosthesis is complemented by a temporary AVF.
Inferior vena caval obstruction is an unusual but important clinical problem for which adequate treatment previously has not been available. Recently, a polytetrafluoroethylene (PTFE) graft with external rigid spiral supports was developed that appeared particularly applicable to the venous system. In 18 dogs a 15 cm length of Impraflex was placed from the proximal right common iliac vein to the inferior vena cava (IVC) at the level of the renal veins after IVC and right iliac vein interruption. End-to-end and end-to-side iliac vein anastomoses were alternated, with and without distal femoral arteriovenous (AV) fistulas (AVFs). At 2 months, with a distal AV fistula, 11 of 12 (92%) grafts were patent, angiograms demonstrated no evidence of intraluminal clot, and there was no hind limb edema. Following AVF ligation 2 months after graft insertion, 10 grafts remained patent, but five developed some intraluminal thrombus and one of them progressed to complete occlusion. Four months after fistula ligation (6 months after graft insertion) 9 of 12 grafts (75%) remained patent. All six grafts without distal AVF were occluded within 1 week. This procedure was performed on one severely symptomatic patient who had IVC occlusion, and currently the patient shows marked improvement. Thus IVC bypass is possible when an externally supported PTFE prosthesis is complemented by a temporary AVF.
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