Relation of carotid stump pressure to safety of carotid artery ligation.

Twenty-four patients underwent ligation of the internal carotid artery for a variety of clinical indications. These included cerebral embolization from surgically inaccessible carotid lesions, carotid disruption and resultant hemorrhage, unreconstructible carotid endarterectomies, and inoperable intracranial carotid aneurysms. The relation of preoperative stump pressures to safety of ligation was evaluated. the data reflect that a systolic stump pressure in excess of 70 mm Hg (13 patients) indicates adequacy of collateral hemispheric blood flow to allow safe ligation of the carotid artery. Pressures of 55 mm Hg or less constitute an unacceptable vulnerability to stroke (two of three patients), and intermediate pressures of 55 to 68 mm Hg constitute a genuine hazard (four of eight patients). The mechanisms of stroke appear to be thromboembolic with late propagation of thrombus into an intracranial low-flow system. Postligation maintenance of appropriate systemic blood pressure is essential, and systemic heparinization is recommended to reduce the morbidity and mortality in patients in the intermediate pressure zone (55 to 68 mm Hg). It is concluded that whenever carotid ligation becomes a therapeutic consideration, the preoperative or preligation measurement of carotid stump pressure is presently the most reliable determinant of safety of the operation.

Intraoperative urinary output does not predict postoperative renal function in patients undergoing abdominal aortic revascularization.

To determine whether intraoperative urinary output was predictive of postoperative renal function, mean urinary output and lowest hourly urinary output were measured in 137 patients during operation for aortic reconstruction. Pulmonary capillary wedge pressure was kept within normal limits. If urinary output was less than 0.125 ml X kg-1 X hr-1, patients were given crystalloid solution, mannitol, furosemide (Lasix), or nothing. For each patient, serum creatinine and blood urea nitrogen (BUN) levels were assayed on postoperative days 1, 3, and 7. There was no significant correlation between intraoperative mean urinary output or lowest hourly urinary output and change from preoperative to postoperative levels of creatinine or BUN. Twenty-one patients had postoperative renal insufficiency; of these, 17 had had renal disease before operation. In these patients as well; mean urinary output and the lowest hourly urinary output did not correlate with change in BUN or creatinine levels. The position of the aortic cross-clamp did not affect these correlations. Therefore, intraoperative urinary output was not predictive of postoperative renal insufficiency in patients undergoing aortic reconstruction.

Spontaneous dissection of the internal carotid artery.

The arteriographic diagnosis of spontaneous, nontraumatic dissection of the internal carotid artery was made in 19 patients and confirmed at operation in ten. The tapered narrowing beginning in or about the carotid bulb and ending at the bony canal was a consistent finding. Four patients had associated aneurysm formation. All but one patient developed an acute hemispheric neurologic deficit as the initial symptom. The deficit was transient in ten and prolonged in eight. The dissection occurred in the outer layers of the media. None of the surgical specimens showed atherosclerosis. Surgical methods of management included segmental resection and grafting, thrombectomy and intimectomy, dilation, and simple ligation. Considerable improvement of luminal diameter occurred in six of seven patients whose arteries were left undisturbed.

Innominate artery endarterectomy. A 16-year experience.

Transsternal endarterectomy was performed in 34 of 37 patients with symptomatic atherosclerosis of the innominate artery, with a mortality of 6%. Thirty of the 32 survivors are asymptomatic at an average of 6.1 years postoperatively. Six of these patients who had ulcerated, nonstenotic atherosclerotic lesions have had complete cessation of preoperative transient ischemic attacks. Normal arterial patency has been maintained for follow-up periods varying from seven months to 16 years.

Aortorenal arterial autografts.

Forty-nine iliac artery autografts were used in the treatment of renovascular hypertension in 45 patients, including six children. The pathological process was fibromuscular dysplasia in 42, atherosclerosis in two, and Takayasu arteritis in one. The internal iliac artery was used as a graft in 39 patients. The common iliac bifurcation was used in two patients, and the external iliac artery in four patients. Common and external iliac artery continuity was restored with Dacron prostheses. Forty-three patients with 47 autografts have been followed up from one to ten years (average three years). Hypertension was cured or improved in 96% of the patients. Serial follow-up arteriograms as late as ten years after surgery have been obtained in 50% of the patients. No late occlusions occurred. Slight autograft dilation occurred seven years postoperatively in one child. Normal growth of the autograft was exhibited in the remaining five children. No evidence of dilation, aneurysm formation, or stenosis appeared in any other grafts, although one patient developed a new lesion distal to her graft.

Carotid plaque hemorrhage. Its role in production of cerebral ischemia.

A prospective study of carotid endarterectomy specimens showed an acute or recent intraplaque hemorrhage in 49 of 53 plaques (92.5%) from symptomatic patients, compared with seven of 26 plaques (27%) from nonsymptomatic patients. Luminal stenosis of greater than 50% was noted in 46 of 53 symptomatic patients (75%), 43 of whose plaques had evidence of multiple hemorrhages. Intimal disruption (ulceration) occurred over protruding mounds of intraplaque hemorrhage and was associated with retinal cholesterol emboli and prolonged neurologic deficits. Mural recesses with the angiographic appearance of ulceration seldom showed intimal breakdown. Eighteen patients continued to have symptoms while receiving aspirin, 13 of whom had had multiple intraplaque hemorrhages. Angioneogenesis occurred within the plaques in response to hemorrhage, creating vascular lesions vulnerable to mechanical stress and capable of producing further hemorrhage or intimal disruption.

Why operate on carotid fibromuscular dysplasia?

Serious antecedent neurologic events occurred in 86 patients operated on for fibromuscular dysplasia (FMD). We applied the following criteria to the assessment of outcome: (1) the lesion should be surgically accessible; (2) the operation should be performed with minimal risk; (3) the operative repair is durable; and (4) benefits of repair are long lasting. Intraluminal dilation fulfills the first criterion: 118 dilations have been performed in 79 patients, with no deaths, three postoperative strokes that recovered completely, and eight single episodes of transient ischemia or amaurosis. The repair was durable, there being one late closure of a dilated artery. There were two subarachnoid hemorrhages, two strokes, and two patients had recurrence of symptoms during the follow-up period. Intraluminal dilation should be offered to patients with symptomatic FMD. A registry of patients with asymptomatic FMD should be established to study its natural history.

Aortorenal arterial autografts: long-term assessment.

Ninety-four iliac arterial autografts were placed in 86 hypertensive patients (age range, 7 to 57 years) during a 16-year period for renal artery reconstruction of nonatherosclerotic lesions. Ten patients were children, and nine patients had a solitary kidney. Ex vivo repair was used in 21 patients. There were no early postoperative deaths; one patient died three months postoperatively of unrelated disease. Two grafts occluded in the early postoperative period. Follow-up of one to 16 years (mean, 5.6 years) was available in 77 patients (93%). Forty-one patients underwent late arteriography at an average of 5.7 years postoperatively. Fifty-one patients (66%) were regarded as cured of their hypertension, the conditions of 25 patients (32%) improved, and the condition of one patient (1.2%) was unchanged. There were no late autograft occlusions. Atherosclerotic anastomotic stenosis developed in one autograft 13 years postoperatively and was relieved by reoperation. Dilation of one autograft was observed seven years postoperatively but did not increase on subsequent arteriograms. In five children, follow-up angiograms showed that the size of the autograft paralleled that of the contralateral renal artery. These results support the preferential use of an autograft during reconstruction of nonatherosclerotic lesions that cause renovascular hypertension.

Measurement of collateral cerebral hemispheric blood pressure by ocular pneumoplethysmography.

A new technic of ocular pneumoplethysmorgraphy for the simultaneous determination of blood pressures in the ophthalmic artery branches of the internal carotid arteries is described. It provides a noninvasive, atraumatic method for assessing hemispheric blood flow. When performed with simultaneous carotid compression, it provides a means for assessing the availability of collateral blood flow to the ipsilateral cerebral hemisphere. Clinical applications related to carotid artery disease and carotid artery surgery are discussed.

Unusual problems of abdominal aortic aneurysms.

Complications other than rupture occurred in 12 per cent of 254 patients operated on for an infrarenal abdominal aortic aneurysm. The unusual problems encountered included aortocaval fistula, inflammatory aneurysm, aortoenteric fistula, aortic thrombosis, peripheral embolization, and retropsoas rupture. The clinical manifestations and management of these lesions are discussed.

Surgery of the aortic arch branches and vertebral arteries.

Experience with 192 operations of vascular reconstruction for atherosclerosis in the proximal brachiocephalic and vertebral arteries is reported. These procedures constitute only 10 per cent of operations for extracranial arterial occlusive cerebrovascular disease at the University of California, San Francisco, in the past 20 years. All patients were asymptomatic. Except for six patients with cerebral embolization from ulcerating lesions, symptoms resulted from cerebral hypoperfusion. Prevention of ultimate stroke was the primary objective of operation in patients with embolization and in patients with stenosis or occlusion of the common carotid arteries. Purely obstructive lesions in the subclavian and vertebral arteries were symptomatic only when there was bilateral involvement and the objective of operation was the relief of disabling symptoms of hypoperfusion for these otherwise essentially benign lesions. Prior correction of associated stenosis of the carotid artery often removed the need for a proximal operation. The majority of the operations were endarterectomy or transposition, or combinations of the two. Cervical bypass grafts, because of their less certain durability, were used only when a more direct operation was neither feasible nor safe.

Renovascular hypertension.

In summary, renovascular surgery has evolved during the past 20 years to become a highly efficacious therapeutic modality provided proper patient selection is practiced. Surgical techniques are now well established, and with the advent of ex vivo techniques practically any extraparenchymal renal artery lesion may be repaired. At present, much investigative work is in progress in an attempt to develop better means of selecting patients who will benefit from renovascular surgery. The newer modifications of renal vein renin assays may permit better patient selection. Many factors must be weighted when considering medical versus surgical management of hypertension. Paramount among these must be the quality of life of the patient. The inconstancy of pressure control and the frequency of undesirable side effects in the more extreme medical regimens are the primary disadvantages of nonsurgial management. An aggressive surgical approach appears to be warranted in selected patients with atherosclerosis and in almost all patients with fibromuscular dysplasia.