Structural failure of Dacron arterial grafts.

The ultimate test of a Dacron (polyethylene terephthalate or PET) arterial prosthesis depends on its ability to retain sufficient strength and durability to function properly for the life of the patient. Because graft recipients appear to be living longer, primarily because of improved medical and surgical treatment of cardiovascular disease, strength and durability of arterial prostheses have become increasingly important. From the time of implantation, all PET prostheses are continuously subjected to the cyclic stresses of pulsatile blood flow with mechanical fatiguing of yarns, as well as chemical and physical alterations associated with biodegradation. Notwithstanding the overall successful use of currently available prostheses, structural failure continues to occur sporadically and is especially noteworthy because of its potentially serious nature and usual occurrence 5 or more years after implantation, when the diagnosis may be overlooked or delayed. A review of the subject is provided based on the premise that timely recognition and appropriate management require a basic understanding of PET prostheses with respect to various fabric constructions and physical properties, graft healing, postoperative dilation, and known causes of structural failure.

Intrinsic Dacron graft failure 19 years post-implantation.

Intrinsic failure of a knitted Dacron aortic bifurcation graft 19 years after implantation is reported. Failure was due to inability of the dilated and deteriorated left graft limb to hold anastomotic sutures. Numerous transverse cracks and breaks were detected in the Dacron filaments, in addition to small holes throughout the fabric structure, and a severe reduction in the yarn's tensile strength. Criteria are defined for establishing a correct diagnosis, and causative factors, incidence, and clinical management are discussed.

Dilative characteristics of Microvel and Vasculour-II aortic bifurcation grafts.

Dilation is inherent to all knitted Dacron arterial prostheses. Insufficient clinical data regarding the usual dilative characteristics of specific grafts confound its significance and management. Alterations in size of all parts of knitted aortic bifurcation grafts (43 Microvel and 37 Vasculour-II) were evaluated by CT scanning in 80 patients; 76 scans were obtained in those with Microvel and 69 in those with Vasculour-II grafts. The mean dilation values were Microvel 54% +/- 16% SD at a mean follow-up of 21 months and Vasculour-II 48% +/- 21% SD with a mean follow-up of 73 months. Serial scans and a linear correlation study indicated that the rate of progressive dilation for both grafts was relatively low. The wide range of dilation values among patients with the same graft type, and even the same implantation time, operated upon by the same surgeon, suggests that multiple etiologic mechanisms are involved. Consequently, all patients must be evaluated individually, preferably with serial scans that evaluate all parts of the graft.

Postoperative dilation of knitted Dacron aortic bifurcation graft.

Dilation is the most common inherent "failure mode" of knitted Dacron aortic prostheses. However, the incidence of graft failure related to dilation is unknown because of insufficient data regarding the occurrence, degree, and prognostic significance of postoperative alterations in graft size. In 1979 we reported that postoperative ultrasonic examinations in 95 asymptomatic patients, selected at random after aortic surgery, revealed dilation of the aortic portion of knitted Dacron bifurcation grafts. The average follow-up was 33 months, and the mean dilation was 18%. This article provides the results of a later follow-up, averaging 175 months, in 32 patients from the 1979 study. CT scanning, rather than ultrasonic imaging, was used to evaluate all parts of the grafts. CT scans disclosed that the three parts of each graft dilated, but the parts did not always dilate uniformly. Mean percent dilation values for the entire series were aortic portion 67% +/- 38% SD; right limb 77% +/- 66% SD; left limb 54% +/- 26% SD. Maximum percent dilation for any part of the grafts ranged from 26% to 367% with a mean of 94%. At least one part of the grafts dilated 100% or greater in 12 patients. Three patients had generalized and saccular dilation of the aortic portion of the prostheses and an anastomotic aortic aneurysm; one patient had a localized aneurysm in the midportion of the right limb. Three of the latter grafts were replaced with woven Dacron prostheses.

Carotid endarterectomy in patients with territorial transient ischemic attacks.

Results are presented of a retrospective analysis of 651 carotid endarterectomies in 605 patients with carotid territorial transient ischemic attacks (TIAs). All operations were performed by the same surgeon in a community hospital from 1963 to 1986. Arteriographic findings consisted of carotid stenosis of 50% or greater in 88.5% of patients and stenosis less than 50% and/or an ulcerated plaque in the remaining 11.5%. Medical risk factors were detected in 92% of patients; hypertension, peripheral vascular disease, and coronary atherosclerosis were most prevalent. All operative procedures were conducted with the patients under general anesthesia, routine shunting, and arterial closure without a patch. The perioperative stroke rate was 1.5% (10 patients); the morality rate was 0.8% (three deaths from myocardial infarction and two from stroke) for a combined stroke and mortality rate of 2.0% (13 of 605 patients). Follow-up (mean 61.8 months) was possible in 570 (96%) of the patients surviving operation without a perioperative stroke. The cumulative probability of late stroke (i.e., cerebral infarct ipsilateral to the operated artery) was 2.5% at 5 years and 8.1% at 10 years. When the perioperative stroke-mortality rate (2.0%) is combined with the data for late ipsilateral stroke, the 5- and 10-year probabilities of ipsilateral stroke were 4.5% and 9.9%, respectively (mean 1% per year for 10-year period). Coronary atherosclerosis accounted for 43% of late deaths and 16% of strokes. The perioperative stroke-mortality rate of 2.0% in this group of patients falls within the acceptable range for carotid endarterectomy in patients with TIA.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary arteriovenous fistulas in association with hereditary hemorrhagic telangiectasia and carotid aneurysm.

A case is presented of a patient with multiple bilateral pulmonary arteriovenous fistulas, hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber Disease), and an intracranial carotid aneurysm. Over a twenty-five year period, the patient has survived several life-threatening complications, and has successfully undergone staged bilateral pulmonary lobectomies and clipping of the carotid aneurysm. Preoperative evaluation included cardiac catheterization studies both with and without temporary balloon occlusion of the pulmonary artery. The pathogenesis, clinical features, pathophysiologic changes, and treatment of pulmonary arteriovenous fistulas are discussed.

Postoperative alterations in size of Dacron aortic grafts: an ultrasonic evaluation.

Reports of aneurysmal dilatation involving Dacron aortic prostheses have raised questions concerning the incidence, degree and significance of postoperative alterations in graft size. Consequently, a study was undertaken to evaluate Dacron graft size by ultrasooud in 95 asymptomatic patients selected at random after aortic surgery. A Vidison Real Time ultrasound unit was used to determine the internal diameter of the aortic portion of the various grafts utilized: 41 Cooley knitted, 25 Vasculour-D; 13 U.S.C.I. ultralightweight; nine Wesolowski Weavenit; and seven DeBakey standard weight knitted. Patients were studied at from two weeks to 138 months postoperatively (average of 33 months). Hypertension was present in 64% of patients. In the total series, the degree of mean dilatation was 17.6%. Average dilatation in patients with normotension was 15% compared to 21% in hypertensive patients. Graphic analysis of the data collected indicated that dilatation of a significant degree occurs in the immediate postoperative period and slowly increases with time; the time regression period and slowly increases with time; the time regression lines for normotensive and hypertensive patients were almost parallel. Results of this clinical study appear to corroborate the results of in vitro quality control tests performed by two graft manufacturers (Meadox and U.S.C.I.).

Complications of peripheral arteriography.

This paper offers an analysis of possible complications of peripheral arteriography. Complications are considered in terms of the most common fundamental problems: 1) reactions to contrast media; 2) vasovagal response to arterial puncture; 3) local hemorrhage; 4) vein and nerve injuries in vicinity of arterial puncture site; 5) subintimal injection of contrast material; 6) arterial thromboembolism; 7) special problems related to catheters and guide wires; and 8) intravascular injection of foreign substances. The paper also provides ten examples of specific clinical conditions caused by arteriographic procedures. Finally, various safeguards in the prevention of complications are discussed.