Aorta-coronary artery revascularization with an expanded polytetrafluoroethylene vascular graft

Aorta-coronary artery revascularization with an expanded polytetrafluoroethylene vascular graft A preliminary report Patients requiring coronary artery surgery may have had bilateral saphenous vein stripping, and the arm veins may not be adequate for use for coronary artery grafting. The internal mammary artery may not be long enough for use for the circumflex or right coronary artery anastomoses. A suitable substitute would be most welcome for these patients or for those with marked varicosities of the saphenous vein. Five patients received expanded polytetrafluoroethylene (PTFE) grafts (Gore-Tex vascular grafts) for coronary artery revascularization because veins of adequate size or length were not available at the time of operation. These five patients are alive 9 to 14 months after graft insertion. Four of the five grafts were patent at the time of restudy 3 to 6 months postoperatively. More follow-up studies for far longer periods of time will be necessary before Gore-Tex vascular grafts can be recommended as the ideal material for coronary artery bypass surgery.

Taro Yokoyama, M . D . , Mohammad A. Gharavi, M.D., Ying-Chien Lee, M . D . , W. Allan Edmiston, M . D . , and Jerome Harold Kay, M.D., Los Angeles, Calif.

A. he autogenous saphenous vein has been utilized successfully as a vascular conduit for coronary artery revascularization since 1967. 1 If the saphenous veins have been removed previously for use as conduits or the saphenous veins are varicose, then the cephalic and basilic veins and the internal mammary arteries can be used. However, if the disease of the right or circumflex coronary arteries is distal, use of the internal mammary artery may not be possible. Harvesting the cephalic and basilic veins of the arm is tedious and more difficult than obtaining the saphenous vein. There has been a need for a vascular prosthesis of a smaller diameter with a patency rate comparable to or better than that of the autogenous saphenous vein grafts. 2 , 3 However, there is no good documentation of From the Sections of Thoracic and Cardiovascular Surgery and Cardiology, the Los Angeles County-University of Southern California Medical Center, Los Angeles, Calif. Aided by a grant from The Los Angeles Thoracic and Cardiovascular Foundation. Received for publication May 11, 1978. Accepted for publication July 12, 1978. Address for reprints: Jerome Harold Kay, M.D., 123 South Alvarado Street, Los Angeles, Calif. 90057.

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long-term patency of prosthetic vascular grafts of less than 5 mm. in diameter in any location. This report presents the preliminary results with five patients who received expanded polytetrafluorethylene (PTFE or Gore-Tex) grafts* because of the inadequate size or elngth of available saphenous veins at the time of coronary artery revascularization (Table I). Case reports CASE 1. A 64-year-old man was admitted to the hospital on Sept. 7, 1976, because of shortness of breath, chest pain, and ankle edema. The patient's history revealed recurrent congestive heart failure of more than 10 years' duration. Left and right heart catheterization with cineangiocardiographyic and coronary arteriographic studies were performed. Pulmonary hypertension with a pulmonary artery pressure of 80/30 mm. Hg and a mean wedge pressure of 26 mm. Hg were noted. The left ventricular pressure was 120/10 mm. Hg. Cineangiocardiograms revealed severe mitral stenosis and calcification. Coronary arteriograms demonstrated 80 to 90 percent occlusion of the left anterior descending coronary artery. The ejection fraction was normal. At operation on Oct. 28, 1976, the calcified mitral valve was replaced with a No. 31 glutaraldehyde-treated porcine *Gore-Tex is a registered trademark of W. L. Gore & Associates, Inc., Newark, Del.

0022-5223/78/100552+04$00.40/0 © 1978 The C. V. Mosby Co.

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Table I. Expanded PTFE (Gore-Tex) graft for coronary artery bypass Case (age, sex) 1 (64, M) 2 (42, M)

surgery

Diagnosis

Procedure

Severe calcific mitral stenosis, occlusion of LAD Anomalous origin of LCA

Mitral valve replacement with No. 31 porcine xenograft; aorta-coronary bypass graft with 3 mm. PTFE graft to LAD Closure of anomalous origin of LCA with 5 mm. PTFE graft from aorta to left main coronary Saphenous vein graft to circumflex and LAD; 3 mm. PTFE graft to RCA

3 (53, M)

Triple-vessel coronary artery disease

4 (54, M)

Triple-vessel coronary artery disease

5 (72, F)

Triple-vessel coronary artery disease

Saphenous LAD; 4 RCA Saphenous LAD; 4 RCA

Follow-up PTFE graft patent 3% mo. postop. PTFE graft patent 5 mo. postop.

vein graft to circumflex and mm. PTFE graft from aorta to

PTFE graft clotted 5 mo. postop.; two saphenous vein grafts patent All grafts patent 6 mo. postop.

vein graft to circumflex and mm. PTFE graft from aorta to

All grafts patent 6 mo. postop.

Legend: LAD, Left anterior descending coronary artery. LCA, Left coronary artery. PTFE, Polytetrafluoroethylene. RCA, Right coronary artery. valve. The patient's saphenous vein was obtained at the time of operation for the graft to the left anterior descending coronary artery; however, this vein had a diameter of only 1.5 mm. after careful dilatation. A 3 mm. expanded PTFE graft was interposed between the aorta and the left anterior descending coronary artery. The patient was placed on a regimen of Coumadin postoperatively because of a porcine xenograft in the mitral position. The patient was restudied 3Vz months later. At the time of readmission, he was active and free of congestive heart failure and angina. Left and right heart catheterization revealed a pulmonary artery pressure of 35/20 mm. Hg, mean 28 mm. Hg, a mean wedge pressure of 14 mm. Hg, a normal left ventricular end-diastolic pressure, and a normal ejection fraction. Coronary arteriograms with injection of the graft revealed a widely patent expanded PTFE graft without any stenosis along the suture line. Seventeen months after the initial operation, the patient is asymptomatic and has increased exercise tolerance. CASE 2. A 42-year-old man was admitted to the hospital on Feb. 9, 1977, because of a sudden choking sensation and right-sided substernal chest pain. Past history revealed onset of substernal chest pain in 1970, but the patient refused further evaluation. He had been taking nitroglycerin intermittently for the relief of angina. He was evaluated by left and right heart catheterization with coronary arteriographic and cineangiocardiographic studies. Pulmonary arterial pressure at the time of heart catheterization was 80/50 mm. Hg with a mean of 33 mm. Hg. Ejection fraction was 0.3. Coronary arteriograms revealed anomalous origin of the left coronary artery, which arose from the main pulmonary artery, and a large, dilated right coronary artery filling the left coronary artery system through collaterals. A left-to-right shunt at the pulmonary artery level was visualized. Because of the patient's intractable angina, surgical treatment was recommended. On March 10, 1977, the anomalous origin of the left main coronary artery from the main pulmonary artery was closed from within the pulmonary artery with a running suture

of 5-0 Prolene. A 5 mm. expanded PTFE graft was inserted between the root of the ascending aorta and the left main coronary artery. Postoperatively, the patient did well and was discharged from the hospital. Five months later, the patient was re-evaluated by heart catheterization, coronary arteriograms and cineangiocardiograms. The ejection fraction had not improved; however, the patient was less symptomatic and the pulmonary arterial pressure had decreased to 35/22 mm. Hg with a mean of 25 mm. Hg. The PTFE graft was widely patent without any sign of suture line stenosis or thrombus formation. Follow-up 12 months later revealed the patient to be doing well. CASE 3. A 53-year-old man was admitted to the hospital with progressive angina of 3 weeks' duration. The patient had received intensive medical treatment which included propranolol and Isordil, but the sysmptoms did not improve. Pulmonary arterial pressure of 25/8 mm. Hg with a mean of 14 mm. Hg and an elevated left ventricular end-diastolic pressure of 24 mm. Hg with a normal ejection fraction of 0.67 were noted. Coronary arteriograms revealed 70 to 80 percent obstruction of the circumflex artery with a relatively large intermediate circumflex coronary artery. The left anterior descending coronary artery had a long segmental occlusion of approximately 80 percent. The right coronary artery was dominant with a 60 to 80 percent diffuse obstruction extending to the cms. At operation on March 2, 1977, cardiac arrest developed during induction of anesthesia. The patient was immediately resuscitated and emergency cardiopulmonary bypass was instituted. The heart was successfully defibrillated, but the anterolateral aspect of the left ventricle became akinetic. The saphenous vein was utilized as a graft between the aorta and the left anterior descending and circumflex coronary arteries. A 3 mm. expanded PTFE graft was used for the right coronary artery revascularization. The patient's postoperative course was uneventful. When restudied 6 months after operation, the saphenous vein grafts to the left anterior descending coronary artery and

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to the circumflex coronary artery were patent, but the expanded PTFE graft to the distal right coronary artery was occluded. The patient is asymptomatic 12 months following the operation. CASE 4. A 54-year-old man was admitted to the hospital because of a history of coronary artery disease, previous myocardial infarction, and angina. Angina had progressed during the previous 2 months and was accompanied by shortness of breath. Cardiac catheterization with coronary arteriographic and cinecardioangiographic studies was performed. The pulmonary arterial pressure was 28/7 mm. Hg with a mean of 12 mm. Hg, left ventricular end-diastolic pressure was normal, and the ejection fraction was 0.5. The coronary arteriogram revealed 100 percent occlusion of the right coronary artery at its origin. There was an 85 percent stenosis of the left anterior descending coronary artery near thefirstseptal branch and a 90 percent lesion of the circumflex coronary artery at the origin of the lateral branch. At operation on March 17, 1977, the patient was found to have very small saphenous veins bilaterally. These vessels were approximately 1.5 to 2 mm. in diameter. The proximal saphenous vein, which was 2 mm. in diameter, was employed for grafts to the left anterior descending coronary artery and the circumflex coronary artery. A 4 mm. expanded PTFE graft was interposed between the ascending aorta and the distal right coronary artery. At the time of restudy 6 months later, the ejection fraction had increased from 0.5 to 0.7. The two saphenous vein grafts and the expanded PTFE graft were widely patent. The patient continues to be asymptomatic 12 months following the operation. CASE 5. A 72-year-old woman was admitted to the hospital with shortness of breath and severe chest pain of sudden onset. Studies revealed a pulmonary arterial pressure of 35/15 mm. Hg, with a mean of 22 mm. Hg, a left ventricular enddiastolic pressure of 22 mm. Hg, and an ejection fraction of 0.4. Also observed were 75 percent stenosis of the circumflex coronary artery, 80 percent stenosis of the left anterior descending coronary artery, and 60 percent diffuse proximal disease of the right coronary artery. Because of the patient's unstable angina and failure of medical treatment to alleviate the patient's pain, an operation was performed. On March 21, 1977, the saphenous vein was used for grafts from the aorta to a branch of the circumflex artery and the left anterior descending coronary artery. Because of the poor quality of the saphenous vein and multiple varicosities, a 4 mm. expanded PTFE graft was used for revascularization of the distal portion of the right coronary artery. Six months after the operation, the patient was re-evaluated by coronary arteriography and cineangiocardiography. All three grafts including the expanded PTFE graft to the right coronary artery were widely patent. Because of an episode of pulmonary embolism, the patient was then placed on a regimen of maintenance anticoagulation therapy with Coumadin. Twelve months after the operation the patient remained completely asymptomatic. Discussion The expanded PTFE (Gore-Tex) graft has been used for systemic pulmonary artery shunt operations in

The Journal of Thoracic and Cardiovascular Surgery

cyanotic infants and for peripheral vascular reconstruction with excellent long-term patency rates. 4 ' 5 The use of a prosthetic vascular graft for coronary artery revascularization has not been widely accepted because of the uncertainty of long-term patency. These grafts are still being carefully evaluated clinically. 2, 3 In our five patients, the expanded PTFE grafts were utilized because of the unusually poor quality of the saphenous vein grafts and the time factor involved in harvesting veins from the arms of these patients. It is hoped that the patency rate of the expanded PTFE (Gore-Tex) grafts interposed between the aorta and coronary arteries will be similar to that of autogenous vein grafts without the necessity of anticoagulation therapy. Excellent techniques in performance of the vascular anastomoses must be followed to achieve good graft patency for the PTFE grafts as well as for saphenous vein grafts. Special tailoring of the proximal anastomosis and the distal end of the graft to make a "cobra head" appearance may be important. A 3 mm. graft may be too small and a 4 mm. graft may be a more suitable size for coronary artery revascularization. The proximal anastomosis is performed with 6-0 Prolene and the distal anastomosis with 7-0 Prolene, as for saphenous vein grafts. With our five patients there were no problems with suture line, especially for the distal anastomosis. It is important to make an accurate measurement between the aorta and the target coronary artery to prevent kinking of the graft. Intraoperative dye injection study should be performed if there is any concern regarding graft patency. There was no intention to give anticoagulation therapy postoperatively to improve the patency rate. The advantages of the PTFE graft are as follows: (1) uniform diameter, (2) virtually no chance of twisting the graft during anastomosis, as the graft itself is rigid enough in comparison with saphenous vein grafts, and (3) ready availability of sterile grafts in case of an emergency. The short-term results with the expanded PTFE graft as a vascular conduit for coronary artery revascularization are encouraging at the present time. However, evaluation of long-term graft patency in the coronary artery position is necessary before these grafts can be recommended for use in preference to autogenous vein grafts. REFERENCES 1 EfflerDB, Favaloro RG, Groves LK, Loop FD: The simple approach to direct coronary artery surgery. J THORAC CARDIOVASC SURG 62:503-510, 1971

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2 Sauvage LR, SchloemerR, Wood SJ, LoganG: Successful interposition synthetic graft between aorta and right coronary artery. Angiographic follow-up to sixteen months. J THORAC CARDIOVASC SURG 72:418-421, 1976

3 Moline JE, Carr M, Yarnoz MD: Coronary bypass with Gore-Tex graft. J THORAC CARDIOVASC SURG 75:769, 1978

4 Gazzaniga AB, Lamberti JJ, Siewers RD, Sperling DR, Dietrick WR, Arcilla RA, Replogle RL: Arterial prosthesis

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of microporous expanded polytetrafluoroethylene for construction of aorta-pulmonary shunts. J THORAC CARDIOVASC SURG 72:357-363, 1976

5 Campbell CD, Brooks DH, Webster MW, Bahnson HT: The use of expanded microporous polytetrafluoroethylene for limb salvage. A preliminary report. Surgery 79:485493, 1976