| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Eur J Cardiothorac Surg 2004;26:599-607
© 2004 Elsevier Science NL
Michael E. DeBakey Department of Surgery, Division of Cardiothoracic Surgery, Baylor College of Medicine and The Methodist DeBakey Heart Center, 6560 Fannin Street, Suite 1100 Houston, TX 77030, USA
Received 15 October 2003; received in revised form 5 April 2004; accepted 21 April 2004.
* Corresponding author. Tel.: +1-713-790-4313; fax: +1-713-790-0202
e-mail: slemaire{at}bcm.tmc.edu
 |
Abstract |
|---|
 Top Abstract 1. Introduction2. Patients and methods3. Results4. DiscussionAppendix A. Conference...References |
|---|
Key Words: Aneurysm • Aorta • Aortic dissection • Endarterectomy • Endovascular stent • Renal arteries
|
1. Introduction |
|---|
|
TopAbstract1. Introduction2. Patients and methods3. Results4. DiscussionAppendix A. Conference...References |
|---|
While visceral endarterectomy is generally safe and effective, it has important limitations, including the risks of vessel thrombosis related to an unsatisfactory endpoint and perforation of the thinned out, fragile vessel wall [2,3]. The friable endarterectomized wall also increases the risk of vessel perforation during the insertion of balloon catheters that are commonly used to deliver renal perfusion. Bypasses to the branch vessels—the traditional alternative to endarterectomy—increase the end-organ ischemic times and may be associated with increased morbidity.
Endovascular stenting has emerged as an accepted strategy for managing visceral arterial stenosis in the setting of both atherosclerotic occlusive disease and aortic dissection [4–6]. Two recent reports have described percutaneous stenting to manage renal artery stenosis either before or after TAAA repair [7,8]. The success of percutaneous visceral arterial stenting, combined with the associated technological advances, has created an opportunity to apply these techniques during open surgery. The purpose of this report is to describe our initial experience with direct deployment of balloon expandable stents into the renal and mesenteric arteries during open TAAA repair.
|
2. Patients and methods |
|---|
|
TopAbstract1. Introduction2. Patients and methods3. Results4. DiscussionAppendix A. Conference...References |
|---|
2.2. Stents
NIRoyal Biliary Premounted Stent Systems (Boston Scientific Ireland, Ltd, Galway, Ireland and Medinol Ltd, Jerusalem, Israel) were used in all cases of visceral stenting in this series. Biliary stents are commonly used for peripheral vascular stenting in the United States. The systems consisted of 9-cell gold-coated stainless steel expandable stents that were premounted on 90-cm balloon delivery catheters (Fig. 1A)
. Two balloon diameters (6.0 and 7.0 mm) and stent lengths (14 and 19 mm) were used in this series. According to manufacturer specifications, both balloons have a maximum rated burst pressure of 12 atm/bar and both stents deploy at 7 atm/bar with a maximum post-dilatation diameter of 8.0 mm (Fig. 1B).
|
For nearly a decade, we have performed TAAA repairs without routinely obtaining preoperative visceral arterial imaging. Decisions regarding treatment were usually made based on direct inspection during operation; we continued to employ this approach throughout this two-year series. Visceral branch vessel stenting was performed in the following situations: (1) in cases of ostial and juxtaostial atherosclerotic occlusive disease, to achieve dilatation of visceral arterial stenosis and avoid endarterectomy, (2) after visceral endarterectomy, to tack down a tenuous endpoint, (3) in cases with tenuous visceral ostia adjacent to the visceral patch suture line, to prevent distortion and kinking, and (4) in cases of branch vessel dissection, to obliterate the false lumen and assure patency of the true lumen. The surgeon positioned and expanded the stents within the affected branch under direct vision, without imaging devices and without guidewires. The proximal end of the stent was usually allowed to extend approximately 2 mm into the aortic lumen. If visceral perfusion was being used, the 9-Fr balloon perfusion catheters were inserted directly through the expanded stents.
Using the indications described above, stents were placed into the visceral branches in 93 patients (25.3%). In nearly half of these cases (n=44, 47%), stents were employed in combination with endarterectomy. Thirty-five patients (9.5%) underwent visceral endarterectomies, but did not have stents placed. The majority of patients (n=239, 65.1%) did not receive either visceral endarterectomy or stenting.
Of the 93 patients who received visceral stents, 80 (86%) had stents placed in one or both renal arteries (Fig. 2) and 36 (39%) had stents placed in the celiac axis and/or SMA. A total of 138 visceral vessels were stented in these patients. Most of the patients (n=54, 58%) received only one stent, while 33 (35%) received two visceral stents, and six (6%) received three visceral stents. No patient received stents in all four vessels. The right renal artery was the most frequently stented vessel (n=58, 62%), followed by the left renal artery (n=40, 43%), the celiac axis (n=22, 24%), and the SMA (n=18, 19%). Forty-four patients (47%) underwent combined visceral endarterectomy and stenting; in most of these cases (n=40), a stent was placed into an endarterectomized vessel.
|
|
|
Intraoperative variables included extent of repair, based on Crawford's original classification [1]. Total clamp time was defined as the time between initial aortic clamping and the removal of all clamps, with restoration of normal blood flow into all vessels; this time was not adjusted when LHB was used. Similarly, renal ischemic time was defined as the time between initial aortic clamping and the restoration of normal blood flow into both renal arteries; this time was not adjusted when LHB or renal perfusion were used. Renal clearance time was the time between administration of intravenous indigo carmine and the appearance of blue dye within the urine.
Regarding outcome variables, operative mortality was defined as death within 30 days of operation or during the initial hospitalization. Hospital-to-hospital transfer was not considered discharge (i.e. patients who died after being transferred were counted as operative deaths). Transfer to a nursing home or rehabilitation center was considered discharge, unless the patient died due to a complication directly related to the operation [15]. The peak serum creatinine level was defined as the highest level within 10 days of surgery; values after postoperative day ten were not used because late elevations were considered to be related to postoperative insults. Acute renal failure was defined as a doubling of serum creatinine, relative to baseline, or the need to initiate dialysis within ten days of surgery [16].
2.5. Statistical analysis
Data were retrieved from a prospectively maintained database. Continuous data are presented as mean±standard deviation. Analyses were performed using SPSS 11.5 for Windows software package (SPSS Inc., Chicago, Illinois, USA). Comparisons between groups were made using 
2 or Fisher's exact test for categorical variables and Student's t-test for continuous variables.
|
3. Results |
|---|
|
TopAbstract1. Introduction2. Patients and methods3. Results4. DiscussionAppendix A. Conference...References |
|---|
|
|
Operative deaths occurred in nine patients (10%) in the stent group. Five of the deaths were due to sepsis/multiple organ failure; two of these were related to the visceral circulation and are presented in detail below. Four deaths occurred following cardiopulmonary complications, including respiratory failure in two patients, pneumonia in one patient, and pulmonary embolism in one.
A comparison of outcomes for the three groups is reported in Table 3. Of note, there were no significant differences in mortality or morbidity between the groups. The highest rate of renal failure (20%) occurred in patients who underwent endarterectomy without stenting. More importantly, despite having substantial risk factors for renal complications, the patients who underwent visceral stenting had an incidence of renal failure that was similar to patients who did not undergo stenting or endarterectomy. The peak serum creatinine was also similar between the groups. The need for dialysis was highest in the stent group. The incidence of gastrointestinal complications was similar among the three groups. Three gastrointestinal complications occurred in the stent group. One patient received celiac, SMA, and right renal artery stents and showered multiple emboli throughout the celiac and mesenteric circulation; this patient is discussed in detail below. The other two patients only had right renal artery stents placed; one developed pancreatitis and the other developed gastric perforation.
|
The second visceral vascular complication occurred in a 74-year-old woman who had previously undergone an extent I TAAA repair and developed an aneurysm involving the remaining distal aorta. She underwent an extent III repair, SMA endarterectomy, and bilateral renal endarterectomies with stenting. On postoperative day one, she developed acute hemoperitoneum requiring emergency reoperation. The perforated left renal artery could not be primarily repaired due to its fragility. The origin of the artery was oversewn and a bypass was performed. Her postoperative course was complicated by renal failure, respiratory failure, empyema, and sepsis, culminating in her death nearly 10 weeks later.
The third patient was an 80-year-old woman with chronic atrial fibrillation who underwent an extent III TAAA repair, endarterectomies of all four visceral vessels, and placement of stents into the celiac, SMA, and right renal arteries. On postoperative day one, she developed severe abdominal distention. Immediate reoperation revealed a splenic infarction, a gangrenous gallbladder, a cecal infarction, two focal areas of small bowel ischemia, and hemorrhagic pancreatitis. Upon opening the aortic graft, all four visceral ostia were found to be patent; after attempting embolectomies of each branch vessel, the graft was closed. The gallbladder, spleen, and cecum were removed. The patient developed severe coagulopathy and bowel edema, necessitating abdominal packing and temporary closure. The patient died later the same day.
The final patient was a 78-year-old man with left renal artery stenosis and a previous infrarenal abdominal aortic aneurysm repair. He underwent an extent IV TAAA repair with placement of a left renal stent and a left renal artery bypass with an 8 mm interposition graft. He developed elevation of his serum creatinine level (peak creatinine 2.1 mg/dl vs. baseline creatinine 1.3 mg/dl) that improved prior to his discharge home on postoperative day 10. A follow-up computed tomography scan obtained 13 months later revealed an atrophic left kidney. Subsequent arteriography confirmed thrombosis of the left renal artery. His renal function remains satisfactory (creatinine 1.6 mg/dl).
3.4. Postoperative visceral branch imaging
Postoperative imaging studies of stented visceral arteries were obtained in eight patients (9%) (Table 4). Two patients underwent multiple studies. The median interval between operation and imaging study was 18 days (range 4–580 days). Renal ultrasound was used on eight occasions. In seven of these studies, the stented renal vessels were not visualized satisfactorily. Patency of stented renal arteries was confirmed by two ultrasound studies. Magnetic resonance angiography (MRA) was used in one patient, but failed to visualize the right renal artery due to an imaging void created by the gold-coated stent. Percutaneous catheter arteriography was performed in two patients, revealing patent bilateral renal stents in one patient and an occluded stented left renal artery in one patient (described above).
|
4. Discussion |
|---|
|
TopAbstract1. Introduction2. Patients and methods3. Results4. DiscussionAppendix A. Conference...References |
|---|
Preoperative percutaneous renal artery stenting has been performed in patients undergoing TAAA repair. Unfortunately, reports regarding this strategy in TAAA patients are limited. Sullivan and Hertzer reported using this approach in a critically ill 66-year-old woman with uncontrolled hypertension, progressive renal insufficiency, pulmonary failure, an atrophic left kidney, 80% stenosis of the right renal artery, and an extent IV TAAA [7]. The authors performed percutaneous balloon dilatation and stenting of the right renal artery, which resulted in rapid clinical improvement. Six weeks later, the patient successfully underwent an extent IV TAAA repair. She developed recurrent renal artery stenosis 10 months after the initial procedure; this was treated with repeat percutaneous balloon dilatation.
This approach may be ideal for patients with asymptomatic aneurysms and renal insufficiency due to renal artery stenosis. Improvement of renal function prior to TAAA repair would likely reduce postoperative morbidity and mortality in this select group. However, it is difficult to speculate the value of preoperative stenting of occult visceral artery stenosis. To identify the small proportion with ostial lesions (stents were placed in only 25% of our patients), this approach would require routine preoperative imaging studies which are costly and carry risks related to contrast material. We hope that our report will serve as a basis for future comparisons between open stenting and preoperative percutaneous stenting.
Percutaneous treatment of renal artery stenosis has also been used to manage acute renal failure after TAAA surgery. Yue and colleagues reported an illustrative case involving a 70-year-old woman who had undergone an extent II TAAA repair and a left nephrectomy; 8 years later, she presented with a symptomatic, recurrent TAAA at the visceral patch [8]. Following urgent redo TAAA repair, she developed acute oliguric renal failure. An aortogram demonstrated an occluded right renal artery that was successfully treated with balloon dilatation and stenting. The patient's renal function returned to baseline and she was discharged ten days after the procedure.
Based on (1) the well established need to address visceral lesions during TAAA repair, (2) the technical limitations of endarterectomy and bypass in this setting, and (3) the recent advances in percutaneous renal artery stenting, including its successful application in patients with TAAAs [7,8], we sought to add visceral stenting to our surgical armamentarium. During this initial experience, we found that balloon expandable stents can be a useful adjunct for optimizing the visceral reconstruction during open TAAA repair. The most important observation in this series was that patients who underwent visceral stenting had a low incidence of postoperative renal failure despite their high prevalence of preoperative renal insufficiency, renal occlusive disease, acute presentation, advanced age, and other risk factors. Despite these encouraging results, several caveats demand emphasis.
Although this report covers a large series of consecutive patients, the lack of randomization and the retrospective nature of the data analysis make it impossible to control the influence of selection bias. Therefore, the results must be interpreted with caution. Furthermore, the patients did not undergo routine postoperative imaging studies to ascertain visceral vessel patency. Catheter arteriography would be the most useful study, but is invasive and has well-established risks. It has been difficult to assess stent patency using non-invasive imaging in our patients. Renal ultrasound rarely provided satisfactory visualization of the renal arteries. Computed tomography was not used because of the artifact caused by metallic stents. Similarly, MRA was not successful because of an imaging void artifact created by distortion of the magnetic field by the gold-coated stents. More importantly, the manufacturer of the stents specifically warns against MRA within eight weeks of implantation because of the risk of stent migration under the strong magnetic field. While we acknowledge that imaging will be a critical component of formal scientific evaluations of this strategy in the future, the associated risks, costs, and other logistical issues precluded us from routinely obtaining these studies. Future studies are needed to assess both early and long-term patency and to determine whether restenosis will be amenable to percutaneous angioplasty [4,7].
The stent system used in this series was selected based largely on its small premounted delivery device, which allowed rapid set-up and deployment. Based on experimental data, the gold-coated stents offered the potential advantage of reducing the risk of thrombosis. Recent clinical trials regarding coronary stenting, however, have demonstrated that patients who received gold-coated stents had a higher risk of coronary restenosis than those who received uncoated stents [19,20]. In response to the concerns raised in the coronary stent literature, Zeller and colleagues reported retrospective data on 219 renal artery stents placed percutaneously in 156 patients; 64 of the stents (29%) were gold-coated [21]. The 12-month restenosis rate was 11% for uncoated stents and 12% for gold-coated stents. Vessel diameter was the only independent predictor of restenosis; there were no cases of restenosis for vessels that were 
7.0 mm. Additional data will be required to establish the relative advantages and disadvantages of using gold-coated stents in the visceral arteries.
Finally, four patients (4%) who underwent stenting experienced major target artery complications, including renal artery rupture in two, celiac/mesenteric embolism in one, and renal artery thrombosis in one. Ivanovic and colleagues recently reported similar complications involving the renal artery—including arterial rupture, flow limiting dissection, and thrombosis/embolus—during 4% (7/179) of percutaneous stenting procedures performed in a tertiary medical center [22]. Although the incidence of early target artery complications in our series was similar to that reported for percutaneous stenting, several technical lessons learned during our experience deserve consideration. Safe deployment requires that the stents are positioned precisely within the proximal portion of the vessel and expanded under direct visualization; insertion into a vessel lumen that is not well visualized is strictly avoided. Insertion of stents into the fragile secondary branches of the visceral vessels is also avoided; each lumen is carefully inspected to determine if early branching occurs. Insertion of stents into the right renal artery after endarterectomy can be treacherous and is only performed when there is substantial concern about an intimal flap and only if the lumen can be well visualized. When dealing with plaques that extend beyond the visible ostia of the right renal artery, primary stenting without endarterectomy seems to be a safer option than endarterectomy alone or with subsequent stenting. Although the left renal artery is more accessible, medial visceral rotation and mobilization of the artery result in a lax artery without the support of surrounding tissues. The combination of a mobile, fragile artery and a fixed, rigid stent can precipitate arterial injury after returning the left kidney to its position in the retroperitoneum. In an effort to prevent this problem, mobilization of the artery is minimized when stenting is being considered. Placing sutures into the stent frame is avoided. When a stented left renal artery must be reattached separately, a woven polyester interposition graft (usually 8 mm diameter) will allow the stent to move with the artery.
In conclusion, visceral arterial stenting appears to be a useful adjunct during TAAA repair. In this setting, stents may be used to secure intimal endpoints after endarterectomy, assist patency of the true lumen when dissection extends into the branch, maintain patent ostia near the patch anastomosis, and allow the safe insertion of balloon perfusion catheters. Based on the encouraging initial results, this strategy warrants further investigation, including formal assessment of patency.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
|
Appendix A. Conference discussion |
|---|
|
TopAbstract1. Introduction2. Patients and methods3. Results4. DiscussionAppendix A. Conference...References |
|---|
Dr LeMaire: This is a difficult area, and there has been a learning curve with this. We're less inclined to do a right renal endarterectomy now that we have the stents. Because we're able to use stents, we can often avoid peeling the intima down the right renal artery and the danger of possibly thinning out the artery too much there.
So, in general, when we do an endarterectomy followed by a stent, it's more often in vessels we have better exposure to, like the left renal, celiac, or superior mesenteric arteries. For the right renal artery, we tend to stent osteal lesions. When we're concerned about doing an endarterectomy because of the possibility of injuring the artery, we're using a stent in the right renal artery as a way of avoiding injury. We make sure we put these stents in under direct vision to make sure we don't create a false plane. We expand the balloon just enough to open the stent. We have direct vision while they're expanding; sometimes we don't need to go to the full 8 mm.
Dr M. Grabenwoger (Vienna, Austria): Are you doing these open stenting by yourself or are you calling a radiologist or cardiologist?
Dr LeMaire: For the first one that we did, which was approximately one year before this series started, we called in a radiologist to provide hands-on instruction with the stents. But every one of them since that first case, which is every one of them in this series, has been placed by us.
Dr Grabenwoger: So you have a stock of different sizes also?
Dr LeMaire: Yes. We have a stock of 6- and 7-mm stents, with 14- and 19-mm lengths, on the shelf and ready to use.
Dr J. Bachet (Paris, France): In general do you decide the operative strategy before the operation, or do you decide to use the stent or dilate the arteries or perform an endarterectomy on the spot, intraoperatively?
Dr LeMaire: In 90% of the cases, the strategy is decided on the spot. There are a few cases where the amount of stenosis is so severe that you can see it on the CT scan. Now that we're not getting arteriograms routinely on these patients, like they were 10–15 years ago, we often don't know what we're going to encounter until we're there. One of the benefits of this stent is that it's ready to use off the shelf. You can inspect the vessels, cut the graft, ask for the stent, and within a minute, you've got it when you're ready to use it. So, we're deciding the strategy in the operating room at the time of directly inspecting the visceral vessels.
|
References |
|---|
|
TopAbstract1. Introduction2. Patients and methods3. Results4. DiscussionAppendix A. Conference...References |
|---|
This article has been cited by other articles:
|
|
 |
|
  J. S. Coselli and S. A. LeMaire Descending and Thoracoabdominal Aortic Aneurysms Card. Surg. Adult, January 1, 2008; 3(2008): 1277 - 1298. [Full Text]
|
|
|
|
 |
|
 R. G. MacArthur, S. A. Carter, J. S. Coselli, and S. A. LeMaire Organ Protection During Thoracoabdominal Aortic Surgery: Rationale for a Multimodality Approach Seminars in Cardiothoracic and Vascular Anesthesia, June 1, 2005; 9(2): 143 - 149. [Abstract] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
