Concomitant renal endarterectomy and aortic reconstruction

Transcription

1 Concomitant renal endarterectomy and aortic reconstruction James W. McNeil, MD, S. Timothy String, MD, and Ralph B. Pfeiffer, Jr., MD, Mobile, Ala. Purpose: This retrospective study is to determine the efficacy and durability of renal endarterectomy in patients undergoing simultaneous aortic reconstruction. In addition, the operative risk to patients with symptomatic and asymptomatic renal artery stenosis is evaluated. Methods: The results of a retrospective study of 101 patients who underwent combined procedures are presented. All patients demonstrated at least a 75% stenosis of the renal artery ostium by arteriography and underwent surgical repair of aneurysmal (n = 33) or aortic occlusive (n = 68) disease. The indications for renal revascularization were hypertension necessitating multiple medications (47%), hypertension combined with renal insufficiency (18%), renal insufficiency alone (5%), and asymptomatic stenosis (30%). Blood pressure and antihypertension medications were monitored during the follow-up period (mean 3.3 years). Results: The perioperative mortality rate was 1%, with a postoperative morbidity rate of 15%. The conditions of 74% of patients with hypertension were improved or cured, 23% were unchanged, and 3% were worse after surgery. Systolic and diastolic blood pressure in all patients remained significantly diminished during follow-up visits at 3 months, 6 months, i year, 3 years, and 6 years (p < 0.01). There was no significant improvement in serum creatinine levels in patients with preexisting renal insufficiency. A smau but statistically significant decrease in systolic blood pressure and serum creatinine level was noted after operative intervention in the symptom-free patients (p < 0.005). There were no deaths in the asymptomatic subgroup, and significant azotemia did not develop in any of these patients after operation. Conclusions: Renal endarterectomy is an effective and durable method of renal revascularization. Furthermore, it is a technique that can be safely combined with aortic surgery and can be considered in the treatment of high-grade, asymptomatic lesions in patients undergoing aortic reconstruction. (J VASC SURG 1994;20:331-7.) In 1975 the multicenter Cooperative Study of Renovascular Hypertension revealed a mortality rate of 25% in patients who underwent combined aortic and renal artery reconstruction. ~ This far exceeded the additive risk expected when either operation is performed alone. Recent series have demonstrated a more acceptable early mortality rate of 5% to 12% with use of aortorenal bypass as the primary method of renal revascularization. 2s Preexisting renal insuf- From the Mobile Infirmary Medical Center and the Department of Surgery, University of South Alabama, Mobile. Presented at the Eighteenth Annual Meeting of the Southern Association for Vascular Surgery, Scottsdale, Ariz., Jan , Reprint requests: S. Timothy String, MD, 171 LouiseUe St., Mobile, AL Copyright 1994 by The Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter /94/$ /6/56256 ficiency has been identified as the single most important risk factor contributing to the mortality rate of combined procedures. 4's The concern of increased operative risk coupled with the uncertainty of the functional significance of asymptomatic renal artery lesions has led to a lack of enthusiasm for simultaneous renal revascularization in patients undergoing aortic reconstruction. The purpose of this study was to evaluate the efficacy and durability of renal endarterectomy and to clarify the risk of combined procedures for patients with symptomatic and asymptomatic renal artery stenosis. The medical records of 101 patients who underwent operative intervention over a 14-year period were reviewed. PATIENTS AND METHODS Between 1978 and 1992, concomitant renal endarterectomy and aortic reconstruction were per- 331

2 332 McNeil, String, and Pfeiffer September 1994 formed in 47 male and 54 female patients. Seventysix percent of patients were smokers and 12% had diabetes. The average age was 64 years (range 41 to 83 years). All patients had at least a 75% stenosis of the renal artery ostium as demonstrated by cut film arteriographies. All underwent surgical repair of aneurysmal (n = 33) or aortic occlusive (n -- 68) disease by prosthetic grafting. Sixty-five patients underwent unilateral renal endarterectomy (37 left, 28 right), and 36 patients required bilateral revascularization. After endarterectomy, reimplantation with a Carrel patch was required in eight accessory renal vessels and in seven renal arteries associated with aneurysmectomy. The indications for renal revascularization were as follows: hypertension necessitating multiple medications (47%); hypertension combined with renal insufficiency (18%); renal insufficiency alone (5%); and asymptomatic renal artery stenosis (30%). Renal insufficiency is defined as a preoperative serum creatinine level exceeding or equal to 2 mg/dl. The functional significance of renal artery stenosis was confirmed before operation by renal vein studies in 10 patients with unilateral stenosis. Patients were monitored during operation with a pulmonary artery catheter. A generous transverse abdominal incision was used on all patients, and exposure of the aorta was accomplished by the transperitoneal approach. The average suprarenal clamp time was less than 50 minutes in all patients whether they were undergoing a unilateral or bilateral endarterectomy. Infrarenal aortic replacement was performed with woven or knitted Dacron grafts. Aortofemoral bifurcation grafts were used in 66, aortoiliac grafts in 30,and tube grafts in 5 patients. Blood pressure was recorded before operation, before discharge, and at follow-up visits of 3 months, 6 months, 1 year, 3 years, 6 years, and 9 years. The mean follow-up time was 3.3 years (range 0.3 to 14 years). The number of antihypertensive medications was noted before operation and at each office visit. In addition, serum creatinine levels were recorded before operation and before discharge. Statistical comparisons were made with Student's t test. Values are expressed as mean plus or minus standard deviation. RESULTS One patient died 2 days after operation (1%) of a massive cerebral vascular accident after aortofemoral bypass and bilateral renal endarterectomy. This patient had severe preoperative and postoperative hypertension and renal insufficiency. Two patients died of myocardial infarction within the first 3 months of surgery, for a late mortality rate of 3%. Eighteen complications occurred in 15 patients, for a postoperative morbidity rate of 15%. The most significant morbidity was the development of acute kidney failure necessitating temporary hemodialysis in five patients. No patient required permanent hemodialysis. Four of these five patients had preexisting renal insufficiency. Their average age was nearly 6 years older than the mean, and all five patients underwent bilateral renal endarterectomy. During the perioperative period, transient azotemia developed in 12 patients, which subsided by discharge. The remainder of the postoperative complications were common to patients undergoing abdominal aortic surgery: myocardial infarction (n = 3), cerebrovascular accident (n = 2), reexploration for bleeding (n = 2), superficial wound infection (n = 2), pulmonary embolism (n = 1), ischemic colitis (n = 1), lower extremity embolization (n = 1), and pneumonia (n = 1). Among the 30 patients with asymptomatic renal artery stenosis, one had a postoperative myocardial infarction and one patient had a superficial wound infection, for a morbidity rate of 7%. Neither significant azotemia after surgery nor renal insufficiency during the follow-up period developed in any of these patients. To assess the immediate blood pressure response of patients with hypertension, four groups (cured, improved, unchanged, and worse) were defined on the basis of the following criteria. Patients in the cured group were those with blood pressure less than 150/90 mm Hg requiring no antihyperteusive medications after operation. Patients in the improved group demonstrated at least a 15% decrease in systolic pressure with fewer medications. Patients were in the unchanged group if less than a 15% decrease in systolic pressure was noted or if the same number of antihypertensive medications was required after operation. Patients in the worse group were those with a 15% increase in systolic pressure or those who required additional antihypertensive medications. The blood pressure response in the 66 patients with hypertension is shown in Fig. 1. Seventy-four percent of these patients were in either the cured or improved group immediately after surgery. The mean number of antihypertensive medications decreased from 2.1 to 0.9 after operation. There was no significant difference in either blood pressure response or morbidity in patients who underwent unilateral versus bilateral renal endarterectomy. In

3 Volume 20, Number 3 McNeil, String, and Pfeiffer 333 loo % m All Htn Pts (66) Unilat (37) Bilat (29) O_ Cured Improved Unchanged Worse Fig. 1. Bar graph demonstrates immediate blood pressure response in patients receiving multiple antihypertension medications. Comparison of unilateral and bilateral procedures is shown. two patients marked elevation of their hypertension developed after operation, and they required increased medication. Both of these patients had undergone bilateral renal revascularization, and postoperative renal nucleotide scanning results on both indicated normal perfusion. Twelve patients initially classified in the cured or improved group required additional antihypertensive medications during the ensuing years. Increases in medications were made at an average of 3 years after operation. Systolic blood pressure in all patients was noted to decrease from 164 _+ 30 mm Hg before operation to 139 _+ 18 mm Hg before discharge (p < 0.001). Likewise, diastolic pressure decreased from mmhgto mmhg (p < 0.001). Therewas also a significant decrease in systolic pressure noted among the 30 symptom-free patients. Recorded values decreased from 140 _+ 17 mm Hg to 132 _+ 11 mm Hg in this group (p < 0.005). As shown in Fig. 2 the decrease in systolic and diastolic pressure for all patients remained significant (p < 0.01) at all of the follow-up times recorded with the exception of 9 years. Although only 17 and nine patients were monitored for 6 and 9 years, respectively, there was no significant difference in preoperative or postoperative blood pressure between this group and patients monitored for shorter periods (p < 0.005). There was no statistically significant decrease in the serum creatinine level noted after surgery in either patients with preexisting renal insufficiency or all patients combined. In six patients chronic kidney failure developed during follow-up at a mean of 3.3 years after operation. Four of these patients had preexisting renal insufficiency. When these four patients were excluded, however, a significant decrease was noted in serum creatinine levels in the remaining patients with preexisting renal insufficiency. Sermn creatinine levels decreased from 2.5_+ 0.8 to 2.1 _+ 0.6 (p < 0.05). There was a small but significant change in serum creatinine levels in the symptom-free patients. Serum values dropped from 1.2 _+ 0.3 mg/dl to 1.0 _+ 0.4 mg/dl (p < 0.005). Forty patients have undergone diagnostic evaluation of renal artery flow during their follow-up. These patients underwent either duplex scanning (n = 20), nuclear scanning (n = 14), or arteriography (n = 6) at an average of 2.1 years after operation: one study revealed occlusion of a renal artery, and two others showed evidence of significant restenosis. During the follow-up period 20 patients died. The causes of death were as follows: heart related (n = 9), kidney failure (n = 3), cerebrovascular accident (n = 2),and other causes (n = 6). Twentyone patients were lost to follow-up. DISCUSSION The first successftil surgical revascularization of renal artery stenosis was performed by combined aortoiliac and renal endarterectomy. 6,7 Since that time, a lack of enthusiasm among surgeons has developed for concomitant aortic and renal artery reconstruction, as well as for the technique of renal

4 334 McNeil, String, and Pfeiffer September 1994 mmhg i 140- ~ Systolic ~_ - _ ~ ~,,~ ~- Diastolic (101) (101) (80) (61) (50) (39) (19) (9) Time (n=) p < Fig. 2. Graph depicts long-term blood pressure response to renal endarterectomy. All postoperative and follow-up blood pressures are significantly decreased from preoperative levels (p < 0.01), with exception of 9-year systolic and diastolic values. endarterectomy. Recent reports have suggested that combined procedures can be performed with acceptable morbidity and mortality rates. 2-s In addition, Stoney et al.7,8 have published reports documenting the safety and efficacy of renal endarterectomy specifically when combined with aortic reconstruction. However, perceived difficulties with renal endarterectomy remain. Concerns include (1) the degree of aortic dissection required; (2) visualization of a clean end point; (3) extended suprarenal clamp time; (4) distal embolization; and (5) the potential for hemorrhage at the intersection of suture lines. The technique of renal endarterectomy requires careful and precise dissection of the upper abdominal aorta and several technical points should be considered. The left renal vein is retracted superiorly and gonadal or adrenal branches of this vessel are sacrificed as needed to permit complete mobilization. Division of the diaphragmatic crura greatly facilitates exposure of the suprarenal aorta allowing placement of a vertical aortic clamp above the level of the superior mesenteric artery. After heparinization and aortic clamping, a longitudinal aortotomy is made, curving posteriorly at the level of the superior mesenteric artery. The renal artery orifices are individually endarterectomized with a dissector blade to circumferentially develop a plane between the atherosclerotic plaque and the aortic media. This plane is carefully extended into the renal artery orifice by providing traction to the specimen while the vessel is gently prolapsed into the lumen of the aorta. This technique allows good visualization of an end point and removal of a clean specimen (Fig. 3). Because of the difficulty of renal artery inversion, orificial endarterectomy should not be attempted if the plaque extends more than several centimeters into the vessel. After renal revascularization the longitudinal aortotomy is closed with a continuous monofilament suture. Once the aortic anastomosis is complete, the aortic clamp is moved to the infrarenal position. The suture line of the aortotomy intersects with the aortic graft anastomosis anteriorly. Two patients in this review required reexploration for bleeding at the aortic anastomosis; In neither case was the intersection of sutures the source of hemorrhage. The effect of renal endarterectomy on hypertension- 74% of patients with hypertension in the cured or improved group-is comparable with reported series of aortorenal bypass. In a recent review by Stewart et al. 9 60% of patients with hypertension undergoing concomitant aortorenal bypass and aortic reconstruction were either cured or improved. 9 This study uses the same criteria defining blood pressure response and allows comparisons of a similar patient population. Shahian et al.3 have demonst.rated 80% of patients in the cured or improved group after combined aortorenal bypass and aortic grafting. The review of concomitant renal endarterectomy and aortic reconstruction by Stoney et al.7

5 Volume 20, Number 3 McNeil, String, and Pfeiffer 335 Fig. 3. Photograph shows atherosclerotic plaque removed by endarterectomy of renal artery orifice. have reported 80% of patients in the cured or improved group. It should be noted that most patients undergoing combined procedures are not rigorously selected for renovascular hypertension. Reconstruction of the abdominal aorta is usually the primary objective. Only 10 patients in this study underwent preoperative renal vein renin determination. Several reports have demonstrated improvement in blood pressure after renal revascularization in more than 90% of carefully selected patients Because of the increased mortality rate of combined aortic and renal procedures in earlier reports, routine revascularization of asymptomatic renal artery lesions has not been widely performed. In addition, because the natural history of atherosclerotic renal artery stenosis had not been well documented until recently, the functional significance of asymptomatic lesions has been uncertain. Dean et al.14 reported the occlusion of renal arteries in 12% of patients medically treated for atherosclerotic lesions. Furthermore, they identified deterioration of renal function in 41% unrelated to adequacy of blood pressure control. Schreiber et al.ls reported progression in 44% and occlusion in 16% of patients with serial arteriograms. Tollefson and Ernst 16 have reported progression in 53% and occlusion in 9% of patients similarly monitored. These latter two studies identified patients with high-grade stenosis to be at increased risk for occlusion. Thirty patients in this study with high-grade, asymptomatic renal artery lesions underwent concomitant endarterectomy at the time of aortic reconstruction. There were no deaths and only two complications. The statistically significant decreases observed in blood pressure and serum creatinine levels are of uncertain clinical significance but are suggestive of improved renal function after operation in symptom-free patients. In addition, these results may indicate that the presence of a significant renal artery lesion alone may be an indication for renal revascnlarization. Once stenosis has progressed to affect changes in renal function, efforts to reverse this trend with revascnlarization are associated with higher mortality rates and poorer results.4,5 This clinical review confirms the efficacy and durability of renal endarterectomy while demonstrating acceptable morbidity and mortality rates in the concomitant treatment of renal artery stenosis and aortic disease. In addition, this technique is a safe, therapeutic option in the treatment of high-grade asymptomatic renal artery lesions in patients undergoing aortic reconstruction.

6 336 McNeil, String, and Pfeiffer September 1994 REFERENCES 1. Franklin SS, Young JD, Maxwell MH, et al. Operative morbidity and mortality in renovascular disease. JAMA 1975;231: Perry MO, Silane MF. Man~tgement ofrenovascular problems during aortic operations. Arch Surg 1984;119: Shahian DM, Najafi H, Javid H, Hunter JA, Goldin MD, Monson DO. Simultaneous aortic and renal artery reconstruction. Arch Surg 1980;115: Tarazi RY, Hertzer NH, Beven EG, O'Hara PJ, Anton GE, Krajewski LP. Simukaneous aortic reconstruction and renal revascularization: risk factors and late results in eighty-nine patients. J VASC SURG 1987;5: Dean RH, Keyser JE, Dupont WO, Nadeau JH, Meacham PW. Aortic and renal vascular disease: factors affecting the value of combined procedures. Ann Surg 1984;200: Wylie EJ, Perloff DL, Stoney RJ. Autogenous tissue revascularization techniques in surgery for renovascular hypertension. Ann Surg 1969;170: Stoney RJ, Messina LM, Goldstone J, ReiUy LM. Renal endarterectorny through the transected aorta: a new technique for combined aortorenal atherosclerosis-a preliminary report, J VASC SURG 1989;9: Stoney RJ, Skioldebrand CG, Qvarfordt PG, Reilly LM, Ehrenfeld WK. Juxtarenal aortic atherosclerosis: surgical experience and fianctional result. Ann Surg 1984;200: Stewart MT, Smith RB, Fulenwider T, Perdne GD, Wells JO. Concomitant renal revascularization in patients undergoing aortic surgery. J VAse SURG 1985;2: Dean RH, Lawson JD, Hollifield DV, Shack RB, Polterauer P, Rhamy RK. Revascularization of the poorly functioning kidney. Surgery 1979;85: Novick AC, Ziegelbaum M, Vidt DG, Gifford RW Jr, Pohl MA, Goormastic M. Trends in surgical revascularization for renal artery disease: ten years' experience. JAMA 1987;257: Hallett JW Jr, Fowl R, O'Brien PC, et al. Renovascular operations in patients with chronic renal insufficiency: do the benefits justify the risk? J VAsc SURG 1987;5: Chibaro EA, Libertino JA, Novick AC. Use of the hepatic circulation for renal revascularization. Ann Surg 1984;199: Dean RH, Kieffer RW, Smith BM, et al. Renovascular hypertension: anatomic and fimctional changes during drug therapy. Arch Surg 1981;116: Schreiber MJ, Pohl MA, Novick AC~ The natural history of atherosclerofic and fibrous renal artery disease. Urol Clin North Am 1984;11: Tollefson DH, Ernst CB. Natural history of atherosclerotic renal artery stenosis associated with aortic disease. J VASE SURG 1991;14: Submitted Feb. 3, 1994; accepted Mar. 23, DISCUSSION Dr. Kimberly Hansen (Winston-Salem, N.C.). The authors have made a convincing argument that transaortic endarterectomy is a useful method of direct aortorenal revascularization when used by skilled surgeons experienced with the technique. A 1% perioperative mortality rate and 15% morbidity rate among patients undergoing combined aortorenal reconstruction are exemplary. In our own center, one third of 478 consecutive renal revascularizations performed for hypertension or renal insufficiency have been combined with aortic repair. In this subgroup, our own perioperative mortality rate has been 2.6%. The main controversy raised by the authors, however, is to extrapolate these results to support interventional management of occlusive renovascular disease in patients without hypertension or renal insufficiency. At our center we do not perform prophylactic renovascular surgery either as an isolated procedure or in combination with aortic repair. To intervene prophylactically before there has been any pathologic consequence related to the renal artery lesion in patients with normal blood pressure without renal dysfimction presumes that these sequelae will develop in a significant percentage of patients which cannot be treated. We do not believe the data provided by the surgical literature support this presumption. Most importantly, the natural history data demonstrating anatomic progression of atherosclerotic renal artery lesions with a decrease in renal size and fianction have examined patients with hypertension. The only available prospective data from Dean and coworkers 14 apply to patients with renovascular hypertension. These were patients whose atherosclerotic lesions had progressed to hypertension with lateralizing fimction studies. In contrast, based on our current knowledge of the progression of silent anatomic lesions to clinical significance, the associated rate of functional decline in the setting of renovascular hypertension, the rate of renal function retrieval after the onset of hypertension, and renal dysfunction contrasted with the anticipated failure rate of renovascular repair, we estimate that only 5% of patients with initially silent lesions would be uniquely benefitted by prophylactic intervention. Given this rate of unique benefit, even the outstanding mortality/morbidity rates and presumed patency rates reported by the authors fail to justify prophylactic repair of a coexisting renal artery lesion during routine infrarenal aortic repair. Our experience and that of others indicates that 60% to 70% of patients with hypertension and renal insufficiency who underwent global renal revascularization will demonstrate improvement in excretory renal function, yet you did not observe a beneficial renal function response. Do you suspect this difference relates to your timing of functional assessment or relates to other issues? When we compared the rate of decline in renal function

7 Volume 20, Number 3 McNeil, String, and Pfeiffer 337 before and after operations in patients with ischemic nephropathy, only patients who demonstrated an early increase in estimated glomerular filtration rate had a decreased rate of decline of glomerular filtration rate on follow-up, In addition to your excellent follow-up hypertension data, do you have follow-up renal function data? We have used renal duplex sonography as an intraoperative assessment of aortorenal reconstruction. In our experience, intraoperative renal duplex scanning has demonstrated 11% incidence of hemodynamic defects requiring immediate revision. A disproportionate share of these defects have occurred after aortorenal endarterectomy as compared with other techniques. What method do you use or advise for intraoperative assessment after renal artery repair? Dr. Ronald J. Stoney (San Francisco, Calif.). I have one concern about the late behavior ofendarterectomy that I believe should be considered. I noticed that there was some kidney failure that appeared during the perioperative period, and there were five patients who had kidney failure later in follow-up. It raises the question of the durability of endarterectomy. We have noticed since this operation has been done for nearly 40 years at the University of California at San Francisco that, like other sites, renal endarterectomy is susceptible to late restenosis. This is caused by either the early recurrence of myointimal hyperplasia or the late progression of atherosclerotic disease. The authors obtained imaging studies in only one third of their patients after repair. Do they have any plans for long-term imaging studies to assess transaortic renal endarterectomy durability in the future? Perhaps some patients with late renal artery restenosis can be identified early so that timely repair would avoid late failure, Dr. James W. McNeil. To address Dr. Hansen's first question regarding evidence of improvement in renal function in patients who underwent surgery, part of the reason that we could not demonstrate a significant decrease in serum creatinine level in patients with preoperative renal insufficiency is that we included in this group the creatinine values of the patients in whom acute kidney failure developed. As I stated earlier, when these patients were excluded from this group, there was a significant decrease in patients with preoperative renal insufficiency, and there was significant decrease in their serum creatinine level after operation. Regarding questions of any foliow-up of renal function data, serum creatinine was not obtained as a routine aspect of patients' long-term follow-up. Regarding the question of follow-up studies, I think the difficulty lies in trying to justify arteriography in patients who are doing well after operation. Until recently, there was no study performed after operation, with the exception of patients in whom acute kidney failure developed, and these patients underwent nuclear scanning. However, now we are using renal artery duplex scanning routinely in patients who have undergone renal endarterectomy, and we found this study to be helpful. If any abnormality is identified on duplex scanning, then these patients receive arteriography. To address Dr. Stoney's question of late failure in the patients in whom chronic kidney failure developed during their late follow-up, we have no data or follow-up studies on these patients. Regarding plans for long-term follow-up, I believe that all patients will be monitored with renal artery duplex scanning in the future, and we are hoping to get good results and data from this study as a screening method after operation. We also use no intraoperative method to assess patency of the endarterectomy.