Use of polytetrafluoroethylene renal bypass

Transcription

1 Use of polytetrafluoroethylene renal bypass grafts for P. Lagneau, M.D., J. B. Michel, M.D., and J. M. Charrat, M.D., Paris, France Fifty-six revascularizations of the renal arteries were performed in 52 patients with renovascular hypertension with the use of polytetrafluorethylene grafts between June 1979 and October 1984, with an average follow-up of months. Ninety-two percent of the patients were considered to have good results (30% cured and 62% improved). Four patients were classified as tmsuccessfially treated; one died postoperatively of myocardial infarction. All patients underwent late angiographic studies, with only one graft thrombosis being identified. No evidence ofanastomotic stenosis, graft dilatation, or false aneurysm occurred during the follow-up period. From this experience, we believe polytetraflnoroethylene grafts are a valuable alternative to other graft materials for renal artery bypass and may be the preferred graft in the management of atheromatous lesions. (J VASC SURG 1987;5: ) Although controversy still surrounds the management of hypertension resulting from renal artery disease, revascularization is considered to be the only means by which renovascular hypertension (RVH) can be cured.1 Revascularization of stenotic renal arteries can be performed either by a surgical procedure or by use of percutaneous transluminal dilatation. However, the respective indications for use of these two procedures are not yet completely defined. Nevertheless, when surgery is performed, several choices for graft material are available for use. Included in these choices are autogenous artery and vein and synthetic conduits. Although only recently introduced, expanded polytetrafluoroethylene (PTFE) conduits have been used for a variety of arterial reconstructions. Because of its ease of suturing and instant availability, we have undertaken an evaluation of the use of the PTFE graft for aortorenal bypass. This report summarizes the experiences in our center with the use of this graft material during a recent 5-year period in the treatment of 56 renal artery stenoses in 52 selected patients who had RVH out of our total experience of 342 revascularizations of the renal artery in 322 patients (16.3%). MATERIAL AND METHODS Fifty-six revascularizations of the renal arteries were performed in 52 patients with the use of PTFE grafts between June 1979 and October Pa- From the Department of Vascular Surgery, Hospital Saint Michel. Reprint requests: P. Lagneau, M.D., Department of Vascular Surgery, Hospital Saint Michel, 33 Rue Olivier de Serres, Paris 75015, France. tients operated on after this date were excluded to provide at least 1 year of angiographic and clinical follow-up after operative interventions. Candidates for PTFE grafting were selected on the basis of aortic wall involvement with large-caliber renal arteries. There were 27 men and 15 women with an average age of 53 _+ 11 years. Diagnosis of RVH was suspected preoperatively on the basis of either positive renal vein renin ratios, a depressor response to captopril administration, or an abnormal rapid-sequence intravenous pyelogram in all patients. The average preoperative blood pressure without treatment was 247 _+ 30 mm Hg and 128 _+ 17 mm Hg for the systolic and diastolic pressures, respectively. Mean diastolic blood pressure during drug therapy before operation remained 183 _+ 14 mm Hg. The cardiac and renal consequences of hypertension were assessed for each patient by calculation of the Sokolow index on the electrocardiogram, the cardiothoracic ratio on chest rocntgcnography, and the determination of scrum crcatinine. The Sokolow index was defined as the sum in millimeters of S wave amplitude in V1 precordial lead and R wave amplitude in Vs and V6 precordial leads; the cardiothoracic ratio is the ratio measured on frontal chest films between the size of the cardiac silhouette and the greatest width of the thorax measured from the inner margins of the ribs. The Sokolow index averaged 36 _+ 10 mm and the cardiothoracic ratio averaged The mean serum creatinine value was mol/l (normal range ~< 110 mol/l). The histopathologic classification of lesions in these 52 patients was as follows: 41 atheromatous lesions, seven Takayasu's disease, and four fibrodys- 738

2 Volume 5 Number 5 Max, 1987 Polytetrafluoroethylene for renal arteu bypass 739 Fig. 1. Preoperative angiogram of an atheromatous stenosis of the left renal artery. Fig. 2. Angiographic follow-up study of the aortorenal FFFE graft performed for the lesion shown in Fig. 1. plasias. Seven patients had total occlusion of the affected renal artery. OPERATIVE MANAGEMENT The most frequently employed surgical approach Was through the flank with resection of the eleventh rib (in 37 patients). A transperitoneal midline xiphoid-to-pubis incision was performed in 11 pa- tients, and three patients had a combined median sternotomy and midline abdominal incision. Unilateral revascularization of the renal artery was performed in 47 patients (Figs. 1 and 2). Bilateral revascularization was performed in fivc patients. However, in two of these cases the PTFE graft was used only on one side. Eight of the patients underwent associated aortic procedures for stenotic

3 740 Lagneau, Michel and Charrat Journal of VASCULAR SURGERY BP (mmhg) 200 Patients Cured Improved All patients,6) (32) (4S) BEFORE SURGERY AFIER SURGERY SERU. DREATININE : ~moi/i~ t = 2.43 p < SBP DBP Fig. 3. Graph shows changes in arterial blood pressure after surgery. 2"5 I 2,0 I '.5 t,.oj 11.5! ol Patients Cured Improved Number of drugs (16) (32) ~ All patients (4e) o.o o.o8 Fig. 4. Graph shows changes in drugs required for blood pressure control after surgery. or aneurysmal lesions of the aorta. Six of these eight patients underwent aortic grafts from infrarenal aorta to the femoral arteries. One patient had a prosthesis inserted from the ascending aorta to the infrarenal abdominal aorta. The remaining patient had a prosthesis inserted from the descending thoracic aorta to the infrarenal abdominal aorta. The sites for aortic implantation of the renal artery bypass were primarily determined by the extent of the aortic lesions and are summarized in Table I. Distal anastomoses on the renal artery in all cases were fashioned end to end. In most cases (33 of the 56 revascularizations), the inner diameter of the PTFE tube was 6 mm. However, other sizes employed included 8 mm in one case, 7 mm in one case, 5 mm in 15 cases, and 4 mm in five cases. Fifteen of the PTFE grafts were of the more recently available "thin wall" variety. Management of four patients with significant tho- SOKOLOW INDEX (mm) j t = 2.43 p < / CARDIOTHORACIC RATIO t = 4.38 p< o.o~ Fig. 5. Graph shows changes in cadiac and renal variables after operation. Table I. Site of aortic implantation of renal PTFE graft No. of arteries Infrarenal aorta 42 Supraceliac aorta 2 Ascending aorta 3 Aortic prosthesis from infrarenal aorta 7 Aortic prosthesis from ascending aorta 1 Aortic prosthesis from descending aorta 1 Total 56 racic aortic involvement from Takayasu's disease requires special comment. One patient had a bypass from the ascending thoracic aorta to the abdominal aorta with revascularization of the left renal artery by a PTFE graft and the right renal artery by a saphenous vein graft. In two other patients direct implantation of the PTFE graft from the ascending aorta to the renal artery was performed with unilateral revascularization in the first case and bilateral revascularization in the second case. In the last patient, a thoracoabdominal approach was necessary fbr performance of an aortic bypass from the descending thoracic aorta to the abdominal aorta with bilater~il revascularization of the renal arteries by a PTFE graft on the right side and a direct reimplantation of the left renal artery. Intraoperative angiography was performed in all cases. All patients received antiplatelet medication (aspirin, 1 gm per day) for at least 6 months. RESULTS Fifty patients underwent a single surgical procedure. In the two other patients, the immediate postoperative arteriogram displayed anatomic defects that necessitated immediate correction. In one pal dent the implantation of a supraceliac bypass appeared stenotic and the PTFE graft was reimplanted!

4 Volume 5 Number 5 Max, 1987 Polytetrafluoroethylene for renal artery, bypass 741 Serum creatinine ( pmol q) (n:31) 200 Sokolow index Imm) {n:25) 6O Cardiothoracic ratio Cn=17) I O 30 ~, ~ Fig. 6. Graph shows cardiac and renal response to operation in subgroup of patients with abnormal values preoperatively. on the ascending aorta. In the second case, evidence of nonoccluding intramural thrombus led to reoperation and thrombectomy. Two patients were followed up for 1 to 12 months, 26 patients for 13 to 24 months, 14 patients for 25 to 36 months, seven patients for 37 to 48 months, and three patients for more than 48 months. With an average follow-up of 25 _+ 7.7 months, the patients were classified after surgery as cured, improved, or failed. The criterion for cure was postoperative blood pressure less than 140/90 mm Hg and a normal postoperative arteriogram. The patients were considered improved if previously uncontrollable blood pressure was controlled medically at 140/90 mm Hg or if there was a decrease in the diastolic pressure of at least 15 mm Hg when compared with preoperative values on the same medication and if the postoperative arteriogram was normal. The other patients were classified as "failed." According to these criteria, four patients were classified as treatment failures. One failure is represented by the single operative death by myocardial infarction, one patient had thrombosis of the graft, one segmental renal infarct occurred, and one dissection of the renal artery distal to the bypass was identified by postoperative angiography. This last patient was subjected to nephrectomy with subsequent improvement in hypertension. The death from postoperative myocardial infarction occurred after management of an aortic aneurysm and stenosis of one renal artery in a patient with symptomatic inoperable coronary artery disease. Forty-eight patients were considered to have good results. Sixteen of these were classified as cured and 32 as improved. The postoperative decrease in blood pressure for these patients was statistically significant (Fig. 3). The number of drugs necessary to control the blood pressure was clearly reduced from before operation to 1.56 _ after operation (Fig. 4). There was also a significant improvement of cardiac and renal variables (Fig. 5). This was particularly evident when preoperative values of these variables were not in a normal range (Fig. 6). Finally, all of these patients underwent repeat follow-up angiographic study at a postoperative time of 14.5 _+ 10 months. Neither anastomotic stenosis, dilatation of the tube, nor false aneurysm formation was noted from these studies (Fig. 7). DISCUSSION Several materials have been used for renal artery bypass during the past three decades. Early in the evolution of renovascular surgery, the use of a Dacron prosthesis was advocated. 2 However, Dacron tubes require larger calibers and have the worst patency of all alternatives because of neointimal proliferation. 3 More recently, venous grafts have been advocated. 4 Although autogenous arterial grafts may provide the best results when analyzed by late angiographic follow-up, they are not always feasibley Finally, although venous grafts have been used widely, their long-term durabili~ has been hindered by aneurysmal dilatation or stenosis. 8 For these reasons, several authors have explored the use of PTFE grafts as a potential improvement in renovascular surgeryy The use of PTFE material for renal revascularization in our series was determined on the basis of two biases. First, the occurrence of anatomic abnormalities observed during follow-up with the other materials such as Dacron and venous grafts is undesirable. Second, the PTFE graft seems particularly suitable for anastomosis to atherosclerotic aortas. In our series, the predominant cause of the arterial

5 742 Lagneau, Michel, and Charrat Journal of VASCULAR SURGERY mediate postoperative angiography. In this manner, any defect is immediately corrected even if it appears of minimal significance. Similarly, the late angiographic follow-up studies demonstrate that early patency is maintained without significant development of stenoses or dilatation. This is particularly important since the "thin wall" variety of PTFE graft has ~ been used preferentially. Finally, the high incidence of blood pressure improvement (92%) when the PTFE graft is used is similar to our previously reported results 1 and demonstrates the accuracy of preoperative patient selection for operation as well as the value of PTFE for use in operative management.- Fig. 7. Angiographic follow-up study of aortorenal PTFE graft 27 months after insertion. lesion was atherosclerosis. Because of the frequent concomitant aortic wall atherosclerosis and the large caliber of the vessel beyond such proximal lesions, we now believe that PTFE grafts are the preferred material in these patients. In this regard, the results of our experience with PTFE grafts are particularly pleasing, for this allows preservation of the saphenous vein for use in coronary artery operations. However, we have not performed complex revascularization with PTFE grafts. We continue to prefer the saphenous vein when such branch disease requires reconstruction. The low incidence of early graft thrombosis in this series is explained in part by the practice of im- REFERENCES 1. Dean RH, Kieffer RW, Smith BM, et al. Renal hypertension. Anatomic and renal function changes during drug therapy. Arch Surg 1981;116: Kaufmann JJ. Dacron grafts and splenorenal bypass in the surgical treatment ofstenosing lesions of the renal artery. Uro~, Clin North Am 1975;2: Dean RH. Late results ofaortorenal bypass. Urol Clin North Am 1984; 11: Lagneau P, Michel JB. Arterial reconstructive surgery, for' renovascular hypertension. Arch Surg 1981;116: Novick AC, Stewart BH, Straftbn RA. Autogenous arterial grafts in the treatment of renal artery stenosis. J Urol 1978;120: Noble MJ, Novick AC, Straffon RA, Stewart BH. Aortorewl reimplantation in treatment of renovascular hypertension. Urology 1979,14:56&9. 7. Libertino JA, Lagneau P. A new method of revascularization of the right renal artery by the gastroduodenal artery. 8urg Gynecol Obstet 1983;156: Stanley JC, Ernst CB, Fry WJ. Fate of 100 aortorenal vein grafts: characteristics of late graft expansion, aneursymal dilatation and stenosis. Surgery, 1973;74: Khault RB, Novick AC, Coseriu GV. Renal revascularization with polytetrafluoroethylene grafts. Cleve Clin Q 1984;51: Lagneau P, Michel JB. Surgical management and results of renal artery revascularization. Int Angiol 1985;4: