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Ann Thorac Surg 1998;65:1442-1444
© 1998 The Society of Thoracic Surgeons

Case Reports

Aortocoronary Bypass Grafting With Expanded Polytetrafluoroethylene: 12-Year Patency

Allison J. McLarty, MDa, Michael R. Phillips, MDa, David R. Holmes, Jr, MDb, Hartzell V. Schaff, MDa

a Section of Cardiovascular Surgery, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, USA
b Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, USA

Accepted for publication November 17, 1997.

Address reprint requests to Dr Schaff, Section of Cardiovascular Surgery, Mayo Clinic, 200 First St SW, Rochester, MN 55905


   Abstract
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 Footnotes
 Abstract
Introduction
 Comment
 References
 
Prosthetic coronary artery bypass conduits are rarely used because the rate of thrombosis is inherently higher than that with autologous conduits. The low medium-term patency rates of prosthetic grafts have restricted their use primarily to patients with inadequate autologous conduits or to selected emergencies. We describe a patient treated with expanded polytetrafluoroethylene who had documented patency 12 years after the operation.


   Introduction
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 Footnotes
 Abstract
 Introduction
Comment
 References
 
Prosthetic grafts are used only rarely for coronary artery bypass because of an anticipated high risk of thrombosis and the general availability of autogenous veins and arteries [1]. Prosthetic conduits have been reserved for difficult situations, such as in patients with inadequate autologous conduits, or for emergency situations in which the need for autologous conduits was not anticipated [2]. Most follow-up data on patients with prosthetic coronary artery bypass conduits have been disappointing because of low medium-term patency rates despite regimens of systemic anticoagulation or antiplatelet therapy or both [3].

This report describes a patient in whom an expanded polytetrafluoroethylene (ePTFE) coronary artery bypass graft was documented to be patent 12 years after operation; segmental neointimal narrowings were successfully treated by balloon angioplasty with stenting.

A 52-year-old man who came to the Mayo Clinic in October 1982 had symptoms of ischemic heart disease. Left ventriculography and coronary angiography showed an ejection fraction of 0.61. Coronary disease involved the left anterior descending artery with a 100% middle occlusive lesion; the first and second obtuse marginal arteries with 40% and 100% occlusions, respectively; and the posterior descending and posterolateral arteries with 90% and 80% obstructive lesions, respectively.

During operation, the greater saphenous veins were discovered to have numerous varicosities with thin, friable walls, deemed unsuitable for use as bypass grafts. The internal mammary arteries were dissected from the chest wall and inspected, but these vessels were extremely small and friable and not usable as coronary bypass grafts. The decision was made to use a synthetic graft, and a thin-walled, 4-mm ePTFE prosthesis was selected.

During the operation, four coronary arteries were bypassed with a circular sequential 4-mm ePTFE prosthesis. The graft was anastomosed to an arteriotomy in the mid-left anterior descending artery with 6-0 Prolene (Ethicon, Somerville, NJ) suture. Side-to-side anastomoses were made between the graft and the first obtuse marginal branch of the circumflex coronary artery and the second obtuse marginal branch. Finally, the graft was anastomosed side-to-side to the right coronary artery. With a partial occlusion clamp in place, the proximal anastomosis between graft and aorta was accomplished with 6-0 Prolene suture.

The postoperative course was unremarkable. Angiography performed 1 week postoperatively showed patency of the graft and good flow through each of the distal anastomoses. The patient was dismissed home with a regimen of aspirin and was able to return to normal activities.

In October 1994, the patient presented with unstable angina. Angiography showed a 90% ostial stenosis of the graft and sequential 90% and 95% narrowings in the graft proximal to the left anterior descending artery anastomosis (Fig 1). Percutaneous transluminal coronary angioplasty was performed. The two distal lesions were dilated, stented with 4-mm Johnson & Johnson (Warren, NJ) stents, and again dilated to 18 atmospheres. The proximal ostial lesion was similarly dilated and stented with a 5- to 9-mm expandable biliary stent. Completion diagnostic angiography showed an excellent result, with Thrombolysis in Myocardial Infarction III flow without residual stenoses (Fig 2). The patient was dismissed to home, pain free, on a medical regimen of aspirin and ticlopidine.



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  		Fig 1. Coronary angiogram in the right anterior oblique projection obtained 12 years after insertion of expanded polytetrafluoroethylene graft. Note the segmental stenoses (arrows) in the prosthetic conduit between the left anterior descending (LAD) and the obtuse marginal (OM) coronary arteries.

 


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  		Fig 2. Right anterior oblique coronary angiogram after percutaneous transluminal coronary angioplasty. The segmental stenoses between the left anterior descending (LAD) and the obtuse marginal (OM) arteries have been successfully dilated.

 

   Comment
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In previous reports with mean follow-up of approximately 12 months, patency rates of ePTFE coronary bypass grafts vary widely, from an average of 60% at 1 year to a mean of 14% at 45 months [2–5]. Reports of longer periods of patency have been sporadic, in the form of case reports [6].

One factor that improves patency of ePTFE grafts is high blood flow. Flow through prosthetic coronary bypass conduits can be maximized by selection of target vessels with large diameter and runoff and, in selected instances, by performance of endarterectomy [5]. In the case reported, the graft was constructed as a circular sequential graft, and in our previous experience with venous conduits, measured blood flow in these grafts averaged 150 to 200 mL/min. We speculate that the circular sequential configuration of the graft improved total graft flow and contributed to the prolonged patency observed. Other factors that have been proposed as contributors to long-term patency are the quality of distal native vessels and ventricular function [2, 3]. Antiplatelet therapy has also been shown to be of benefit [7], but the role of systemic anticoagulation remains unclear.

Late failure of saphenous vein grafts is usually caused by development of atherosclerotic narrowing, and percutaneous transluminal coronary angioplasty and stenting of focal vein graft lesions have been successful [8]. Late stenosis of prosthetic conduits is usually caused by pseudointimal proliferation. These narrowings in the ePTFE graft of our patient were short and relatively discrete, and angioplasty with stenting yielded an excellent anatomic result, thus avoiding reoperation.

Although ePTFE is not used widely in the current practice of coronary surgery, the late outcome in our patient demonstrates the value of its consideration when no alternatives with autologous tissue exist. When an ePTFE graft is chosen, consideration should be given to maximizing flow with a circular sequential configuration and using the newer grafts designed to augment flow with a distal arteriovenous fistula.


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Nothing in this publication implies that Mayo Foundation endorses any product mentioned in this article.


   References
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 Footnotes
 Abstract
 Introduction
 Comment
 References
 

  1. Molina J.E., Carr M., Yarnoz M.D. Coronary bypass with Gore-Tex graft. J Thorac Cardiovasc Surg 1978;75:769-771.[Abstract]
  2. Hehrlein F.W., Schlepper M., Loskot F., Scheld H.H., Walter P., Mulch J. The use of expanded polytetrafluoroethylene (PTFE) grafts for myocardial revascularization. J Cardiovasc Surg (Torino) 1984;25:549-553.[Medline]
  3. Sapsford R.N., Oakley G.D., Talbot S. Early and late patency of expanded polytetrafluoroethylene vascular grafts in aorta-coronary bypass. J Thorac Cardiovasc Surg 1981;81:860-864.[Abstract]
  4. Tomizawa Y. Vascular prostheses for aortocoronary bypass grafting: a review. Artif Organs 1995;19:39-45.[Medline]
  5. Scheld H.H., Gorlach G., Moosdorf R., Loskot F., Hehrlein F.W. PTFE grafts to the right coronary artery following endarterectomy. Herz 1987;12:237-240.[Medline]
  6. McCullough J.N., Abel R.M., Rubenstein H. Polytetrafluoroethylene graft for spontaneous coronary dissection: 7-year follow-up. Ann Thorac Surg 1990;50:663-664.[Abstract/Free Full Text]
  7. Hancock J.B., Forshaw P.L., Kaye M.P. Gore-Tex (polytetrafluoroethylene) in canine coronary artery bypass. J Thorac Cardiovasc Surg 1980;80:94-101.[Abstract]
  8. Laham R.J., Carrozza J.P., Berger C., Cohen D.J., Kuntz R.E., Baim D.S. Long-term (4- to 6-year) outcome of Palmaz-Schatz stenting: paucity of late clinical stent-related problems. J Am Coll Cardiol 1996;28:820-826.[Abstract]



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This Article
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Hartzell V. Schaff
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