Surgical treatment of aneurysms of the abdominal and thoracic aorta

The danger of an arteriosclerotic abdominal aortic aneurysm is clearly related to the size of the aneurysm. From available clinical data it seems logical to recommend elective surgical excision and graft replacement of abdominal aneurysms 6 cm or greater in diameter because of the considerable danger of rupture of untreated aneurysms of this size. Although small aortic aneurysms do rupture, most patients with small abdominal aneurysms may be safely followed with examination at regular intervals. Surgery is reserved for those who demonstrate evidence of aneurysm expansion. The operative mortality rate for elective surgical excision of abdominal aortic aneurysms is by no means negligible but has probably diminished recently to levels of approximately 5% in the hands of experienced surgeons. Achievement of an operative mortality rate in this range requires sensible case selection, expeditious operative management and skillful postoperative care with particular attention to problems of hypoxemia in the early postoperative period.Patients with ruptured abdominal aortic aneurysms require immediate aneurysm resection for survival. Of those patients with ruptured abdominal aneurysms who reach the hospital alive, approximately 60% should be salvaged at present by emergency surgery.The prognosis of the patient with a thoracic aortic aneurysm depends upon the etiology of the aneurysm. Syphilitic aneurysms of the thoracic aorta are now fortunately rare but appear to have a high incidence of rupture. The prognosis of patients with arteriosclerotic aneurysms, which characteristically involve the descending thoracic aorta, appears to be considerably better than that of patients with aneurysms of the abdominal aorta for unknown reasons. Since the removal of thoracic aneurysms ordinarily requires extracorporeal bypass and is associated with an operative mortality rate in the range of 20%, considerable judgment must be exercised in case selection for elective resection of such aneurysms.The surgery of dissecting aneurysms of the thoracic aorta has recently been modified by the widespread acceptance of antihypertensive drug therapy for acute dissection. Surgery may be reserved, hopefully on an elective basis, for those patients with significant aortic valvular insufficiency, significant aneurysmal dilatation of the dissected aorta, or symptomatic involvement of a major aortic branch in the dissection.