(Radiology. 2000;215:414-420.)
© RSNA, 2000
Vascular and Interventional Radiology |
Treatment of Leaks after Endovascular Repair of Aortic Aneurysms1
Johannes Görich, MD,
Norbert Rilinger, MD,
Roman Sokiranski, MD,
Stefan C. Krämer, MD,
Cengiz Ermis, MD,
Ansgar Schütz, MD,
Hans-Jürgen Brambs, MD,
Joachim Söldner, MD,
Werner Kaiser, MD,
Ludger Sunder-Plassmann, MD and
Reinhard Pamler, MD
1 From the Departments of Radiology (J.G., N.R., R.S., S.C.K., C.E., A.S., H.J.B.) and Thoracic and Vascular Surgery (L.S.P., R.P.), University of Ulm, Steinhoevelstrasse 9, 89075 Ulm, Germany; and the Department of Diagnostic and Interventional Radiology, University of Jena, Germany (J.S., W.K.). Received May 29, 1998; revision requested July 16; final revision received September 14, 1999; accepted September 24. Address correspondence to J.G.
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Abstract
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PURPOSE: To evaluate leaks after the endovascular repair of aortic aneurysms and treat them with occlusive therapy.
MATERIALS AND METHODS: Seventy patients (11 women, 59 men), aged 26–82 years (mean, 69.2 years), underwent transfemoral insertion of endoluminal stent-grafts for treatment of aortic aneurysms. Indications were traumatic pseudoaneurysms (n = 5) or arteriosclerotic aneurysms (n = 65). Aneurysms were thoracic (n = 5) or infrarenal (n = 65). To exclude the possibility of leaks, spiral computed tomography (CT) was performed at 3-month intervals. Patients with leaks that persisted unchanged longer than 3 months were referred for angiography and occlusive therapy.
RESULTS: At CT, 21 leaks were identified in 17 of 70 patients (24%). Only 11 of those 17 patients (65%) had leaks identified with conventional aortography. Selective angiography, however, depicted all of these. Eighteen of 21 leaks proved amenable to occlusive treatment: surgery (n = 1), further stent implantation (n = 4), or embolization (n = 13). In one leak, spontaneous occlusion occurred after 3 months. Two leaks in either the iliolumbar or the median sacral artery were inaccessible; one remained untreated, and the other was unsuccessfully treated. Mean follow-up of occlusive therapy was 6.8 months (range, 2–14 months).
CONCLUSION: Successful occlusion of perigraft leaks is feasible in most cases and can be performed without major complications.
Index terms: Aneurysm, aortic, 56.731, 56.732, 94.1222, 94.731, 94.732, 98.1222, 98.12915, 98.731, 98.732 • Aorta, angiography, 94.1222, 94.1225, 98.1222, 98.1225 • Aorta, CT, 94.12915, 98.12915 • Aorta, grafts and prostheses, 56.1268, 94.1268, 98.1268 • Aorta, interventional procedures, 94.1264, 94.1268, 98.1264, 98.1268 • Aortography, 94.1211, 98.1211 • Grafts, interventional procedures
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Introduction
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Reports in the literature (1,2) indicate that leaks after the endovascular treatment of aneurysms occur in 3%–44% of patients. Leaks may originate at both the proximal and distal ends of the graft. These are so-called perigraft leaks, according to the classification by White et al (3). Furthermore, repeat perfusion of the aneurysmal sac may occur from an artery, such as the lumbar or inferior mesenteric artery, that is covered by a stent; this is called an endovascular leak. The importance of all leak types remains controversial. There is evidence, however, that leaks may be associated with an increased risk of rupture (3,4). On the basis of these findings, it has been our radiology department's practice to recommend occlusive treatment of any leak that persists unchanged for more than 3 months. The purpose of our study was to evaluate leaks after the endovascular repair of aortic aneurysms and treat them with occlusive therapy.
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MATERIALS AND METHODS
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Between October 1995 and March 1998, 70 patients (11 women, 59 men), aged 26–82 years (mean, 69.2 years), underwent transfemoral insertion of endoluminal stent-grafts for the treatment of aortic aneurysms at the University Hospitals of Ulm and Jena in Germany. Indications for treatment included traumatic pseudoaneurysms (n = 5) or arteriosclerotic aneurysms (n = 65). Aneurysms were thoracic (n = 5) or infrarenal (n = 65).
All procedures were performed in the surgical suite by a radiologist (J.G., N.Z.) and a vascular surgeon (R.P.). A Siremobil 2000 (Siemens, Erlangen, Germany) was used for fluoroscopic guidance. Tube prostheses were implanted in six patients (three with thoracic aneurysms and three with infrarenal aneurysms). Most patients (n = 37) with aneurysms of the abdominal aorta received a Vanguard bifurcation graft (Boston Scientific, Hilden, Germany), which was inserted by using a 21-F insertion set.
In two patients with aneurysms of the thoracic aorta and in one patient with an infrarenal aneurysm with necks that exceeded 24 mm in diameter (length, 
20 mm), the Corvita endoluminal vascular prosthesis (Corvita Europe [known as Schneider worldwide], Brussels, Belgium) was used; the Stenford (Stenford Groupe Valendons, Nanterre, France), in one patient; and the Talent (Hosmed, Oberhaching/Munich, Germany), in 29 patients. The device description and implantation technique have been described elsewhere (1). The duration of the implantation procedure was 1–3 hours. Informed consent was obtained from all patients prior to the treatment.
To monitor the prostheses' position and seal, pre– and post–stent placement, contrast material–enhanced spiral computed tomographic (CT) examinations (CT Twin, Elscint, Haifa; or Somatom Plus S, Siemens) were performed in all patients. Parameters were a pitch of 1; section thickness, 5.5 mm; increment, -2.5 mm [caudal to cranial]; contrast medium (iopamidol [Solutrast 300; Byk Gulden, Constance, Germany]) volume, 150 mL; flow rate, 2.5 mL/sec; and delay, 45 seconds. Additional sections were obtained at 100 seconds; pitch, 1.5; section thickness, 5.5 mm; increment, 2.5 mm [cranial to caudal]). Additional imaging was performed at the post–stent placement examination.
Follow-up CT and color duplex flow ultrasonography (US) (Kranzbühler; Solinger, Germany) were completed within the 1st week after stent placement and then every 3 months in all patients. All patients were available for follow-up examination and under-went CT after treatment. CT was performed within the first 2 years after intervention (218 follow-up CT examinations, 3.1 CT examinations per patient).
Once detected with CT, leaks were followed up for 3 months with clinical examination and US until the next CT examination; if the leak was still present at that time, we proceeded to occlusive treatment. CT images served as orientation "road maps" for angiography. Based on the configuration of the leak and its localization at CT, precise determination of the cause of the leak often was possible.
In those cases in which there was evidence of an endovascular leak at CT, intraarterial angiography (Polytron 40; Siemens) was performed within 2 days. For safety reasons and to verify the CT information, a complete angiographic examination was performed. The protocol included abdominal aortography (5-F pigtail catheter) in at least two planes (with a long series to detect late leaks), then selective angiography with a 5-F catheter (Cobra, Boston Scientific Scimed; or Sidewinder, Cordis, Haan, Germany) at the proximal end of the prosthesis, and, finally, visualization of the internal iliac arteries bilaterally and visualization of the superior mesenteric artery. If selective catheterization of the contralateral internal iliac artery proved unsuccessful, angiography was repeated the next day from the contralateral side to reduce the total examination time per day.
If a perigraft leak originating at the upper or lower margin of the prosthesis was identified, a 5-F catheter (Cobra, Internal Mammary [Boston Scientific Scimed], or Sidewinder) was introduced at the site of the leak. Except in the first three patients, in whom the 5-F catheter was used for embolization, a coaxial catheter (Tracker 18; Rehaforum, Cologne, Germany) was advanced beyond the mouth of the leak into the aneurysmal sac, and embolization with up to 25 minicoils (Target; Boston Scientific Scimed) began. In all patients, embolization was performed by using coils of 2–8 mm diameter. To prevent persistence of the leak, closure of the entire open aneurysmal sac was attempted at the entry site. In the first three patients, only the entry site itself was embolized.
In two patients, reperfusion of the aneurysmal sac via the superior mesenteric artery occurred through the inferior mesenteric artery. In these patients, the origin of the inferior mesenteric artery was accessed in a superselective way by using a coaxial system via the marginal artery of the colon (n = 1) or the Riolan anastomosis (n = 1) and was sealed with minicoils.
In the two patients with leaks supplied by the lumbar arteries, the vessels' small diameters precluded a direct approach to the feeding artery. In such leaks, the collateral vessel of the iliolumbar artery was occluded with minicoils from the internal iliac artery as peripherally as possible. If follow-up CT 3 months later demonstrated that the leak was being maintained by additional tributaries, the leak from the contralateral iliolumbar artery also was embolized.
The first three of four patients with leaks were treated with a second covered stent (Boston Scientific) because of a perigraft leak at the beginning (n = 1) or end (n = 2) of the stent. The fourth patient with an infrarenal aortic aneurysm was treated with a second endoprosthesis for a late leak due to a rupture in the middle of the stent seen at 1-year follow-up. One other patient with an aneurysm of the thoracic aorta was found to have a complete rupture of the prosthesis; conventional radiography showed a wide dehiscence of the stent mesh that could only have been due to a complete rupture of the prosthesis. The patient underwent elective surgical stent revision several weeks later.
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RESULTS
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Follow-up CT revealed 21 leaks in 17 of 70 patients (24%) treated. Aortography with a pigtail catheter immediate to the proximal aspect of the prosthesis depicted leaks in only 11 of these 17 patients (65%); selective or superselective angiography, however, depicted the leaks in all 17 patients. Three of 22 patients (14%) with a patent inferior mesenteric artery had an endovascular leak diagnosed with CT and confirmed with angiography of the superior mesenteric artery. In four of 17 patients (24%), leaks were supplied by more than one source: All four exhibited perigraft leakage at the proximal aspect of the prosthesis with one additional entry from the inferior mesenteric artery (n = 2) or at the distal right limb of the prosthesis (n = 2). In all four patients, the second leak was detected at the next 3-month follow-up examination; these patients had to undergo another embolization procedure. Successful occlusion occurred in 18 of 21 leaks (86%).
Seventeen of 21 leaks (81%) were occluded with percutaneous methods. There was spontaneous occlusion after 3 months in one leak (5%). Successfully occluded leaks responded to further stent placement (n = 4 [19%]), surgery (n = 1 [5%]), or embolization (n = 13 [62%]) (Table). Thus, successful outcome was achieved in 90% of all leaks treated. Two leaks (10%) proved untreatable with interventional methods: In two patients with very small endovascular leaks supplied either by the right lumbar artery via the iliolumbar artery originating from the internal iliac or by the median sacral artery, the feeding vessels were of such small caliber as to preclude embolization at a site sufficiently peripheral, so that the leak, supplied by collateral vessels, persisted.
Because of the small diameter of the feeding arteries and because of the long approach, direct entry into the aneurysmal sac was not possible in a minority of our patients. In one patient with an aneurysm of the thoracic aorta, it was believed that damage to the prosthesis occurred during its introduction that resulted in the rupture of the stent mesh. CT revealed severe distortion of the stent geometry. The patient underwent elective surgery several weeks later for surgical replacement of the stent.
Late onset of endovascular leaks after 3 and 12 months occurred in two patients in whom prostheses were primarily sealed. In the first patient, the leak was supplied by a lumbar artery not seen at the first CT examination. The second patient, who had undergone placement of a tube prosthesis for treatment of an aneurysm of the infrarenal abdominal aorta, showed rupture of the stent mesh after 12 months, despite the initial adequate seal of the prosthesis. In this patient as well, there was a tear in the stent covering. The leak was successfully occluded with an additional endoprosthesis.
Complications of occlusive treatment did not occur. In no patient did we see neurologic deficits or infections. As of the time this article was completed, we have observed no recurrences.
Mean follow-up after the initial treatment of the leak was 6.8 months (range, 2–14 months).
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DISCUSSION
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One of the most feared events complicating the endovascular extirpation of aneurysms is rupture despite endovascular treatment. Several individual cases in which the outcomes usually were fatal were reported in the literature (3,4).
On the basis of reports in the literature, endovascular leaks as a complication of endovascular aneurysms of the abdominal aorta occur in 2%–46% of patients (2,5–8). Leaks may originate at both the proximal and distal ends of the graft (Fig 1). These are the perigraft leaks, according to the classification by White et al (3). Reasons for the leaks include inappropriate endovascular repair rather than surgical bypass because of a short aneurysmal neck or because of the proximity of the renal arteries. Other reasons are of a technical nature and may occur during the release of the prosthesis. Leaks occurring at the proximal end of the graft (Fig 2), in particular, are predisposed to the danger of rupture. Furthermore, reperfusion of the aneurysmal sac may occur via the lumbar, sacral, gonadal, accessory renal, or inferior mesenteric arteries. Of these endovascular leaks, 40%–67% thrombose spontaneously, while 20% rupture the aorta (8). Spontaneous closure of a leak after more than 6 months is rare (9). Retrograde endovascular leaks are, at the present state of endovascular technique, probably unavoidable. In our patient groups, six of 70 (9%) patients had this leak, which persisted unchanged for several months (Fig 3).
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Figure 1a. Prosthesis in a 77-year-old male patient after endovascular implantation. (a) Transverse CT scan shows a large perigraft leak (arrow) adjacent to the prosthesis. (b) Selective coronal angiogram obtained adjacent to the lumen of the prosthesis shows a large area of extraluminal contrast medium on the right side (solid arrow), with filling of the lumbar arteries (open arrows). (c) Coronal angiogram after embolization with multiple minicoils, which reach down to the end of the prosthesis, shows no further contrast medium extravasation.
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Figure 1b. Prosthesis in a 77-year-old male patient after endovascular implantation. (a) Transverse CT scan shows a large perigraft leak (arrow) adjacent to the prosthesis. (b) Selective coronal angiogram obtained adjacent to the lumen of the prosthesis shows a large area of extraluminal contrast medium on the right side (solid arrow), with filling of the lumbar arteries (open arrows). (c) Coronal angiogram after embolization with multiple minicoils, which reach down to the end of the prosthesis, shows no further contrast medium extravasation.
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Figure 1c. Prosthesis in a 77-year-old male patient after endovascular implantation. (a) Transverse CT scan shows a large perigraft leak (arrow) adjacent to the prosthesis. (b) Selective coronal angiogram obtained adjacent to the lumen of the prosthesis shows a large area of extraluminal contrast medium on the right side (solid arrow), with filling of the lumbar arteries (open arrows). (c) Coronal angiogram after embolization with multiple minicoils, which reach down to the end of the prosthesis, shows no further contrast medium extravasation.
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Figure 2a. (a) Transverse CT scan obtained after implantation of a prosthesis in an 80-year-old male patient shows a large leak (straight arrow) ventral to the prosthesis (curved arrow). (b) Lateral aortogram shows a ventral collection of contrast medium (open arrow) fed by the site of the leak (solid arrow). (c) Coronal selective angiogram obtained after the introduction of a 5-F selective catheter into the site of the leak shows a broad outflow of contrast medium (solid arrows) around the right limb of the prosthesis and through the lumbar vessels (open arrows). (d) Transverse CT scan obtained at 3-month follow-up demonstrates a persistent caudal leak (arrow) ventral to the prosthesis. (e) Coronal CT scan shows the introduction of a coaxial catheter past the right limb of the prosthesis into the leak (curved arrow), with filling of the left lumbar branch (straight open arrow). Note that the proximal extravasation on the right has been occluded (straight solid arrow). (f) Final coronal angiogram obtained after complete embolization of the lumbar branches and the aneurysmal sac shows the sealed prosthesis (arrows), without perigraft extravasation of contrast medium.
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Figure 2b. (a) Transverse CT scan obtained after implantation of a prosthesis in an 80-year-old male patient shows a large leak (straight arrow) ventral to the prosthesis (curved arrow). (b) Lateral aortogram shows a ventral collection of contrast medium (open arrow) fed by the site of the leak (solid arrow). (c) Coronal selective angiogram obtained after the introduction of a 5-F selective catheter into the site of the leak shows a broad outflow of contrast medium (solid arrows) around the right limb of the prosthesis and through the lumbar vessels (open arrows). (d) Transverse CT scan obtained at 3-month follow-up demonstrates a persistent caudal leak (arrow) ventral to the prosthesis. (e) Coronal CT scan shows the introduction of a coaxial catheter past the right limb of the prosthesis into the leak (curved arrow), with filling of the left lumbar branch (straight open arrow). Note that the proximal extravasation on the right has been occluded (straight solid arrow). (f) Final coronal angiogram obtained after complete embolization of the lumbar branches and the aneurysmal sac shows the sealed prosthesis (arrows), without perigraft extravasation of contrast medium.
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Figure 2c. (a) Transverse CT scan obtained after implantation of a prosthesis in an 80-year-old male patient shows a large leak (straight arrow) ventral to the prosthesis (curved arrow). (b) Lateral aortogram shows a ventral collection of contrast medium (open arrow) fed by the site of the leak (solid arrow). (c) Coronal selective angiogram obtained after the introduction of a 5-F selective catheter into the site of the leak shows a broad outflow of contrast medium (solid arrows) around the right limb of the prosthesis and through the lumbar vessels (open arrows). (d) Transverse CT scan obtained at 3-month follow-up demonstrates a persistent caudal leak (arrow) ventral to the prosthesis. (e) Coronal CT scan shows the introduction of a coaxial catheter past the right limb of the prosthesis into the leak (curved arrow), with filling of the left lumbar branch (straight open arrow). Note that the proximal extravasation on the right has been occluded (straight solid arrow). (f) Final coronal angiogram obtained after complete embolization of the lumbar branches and the aneurysmal sac shows the sealed prosthesis (arrows), without perigraft extravasation of contrast medium.
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Figure 2d. (a) Transverse CT scan obtained after implantation of a prosthesis in an 80-year-old male patient shows a large leak (straight arrow) ventral to the prosthesis (curved arrow). (b) Lateral aortogram shows a ventral collection of contrast medium (open arrow) fed by the site of the leak (solid arrow). (c) Coronal selective angiogram obtained after the introduction of a 5-F selective catheter into the site of the leak shows a broad outflow of contrast medium (solid arrows) around the right limb of the prosthesis and through the lumbar vessels (open arrows). (d) Transverse CT scan obtained at 3-month follow-up demonstrates a persistent caudal leak (arrow) ventral to the prosthesis. (e) Coronal CT scan shows the introduction of a coaxial catheter past the right limb of the prosthesis into the leak (curved arrow), with filling of the left lumbar branch (straight open arrow). Note that the proximal extravasation on the right has been occluded (straight solid arrow). (f) Final coronal angiogram obtained after complete embolization of the lumbar branches and the aneurysmal sac shows the sealed prosthesis (arrows), without perigraft extravasation of contrast medium.
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Figure 2e. (a) Transverse CT scan obtained after implantation of a prosthesis in an 80-year-old male patient shows a large leak (straight arrow) ventral to the prosthesis (curved arrow). (b) Lateral aortogram shows a ventral collection of contrast medium (open arrow) fed by the site of the leak (solid arrow). (c) Coronal selective angiogram obtained after the introduction of a 5-F selective catheter into the site of the leak shows a broad outflow of contrast medium (solid arrows) around the right limb of the prosthesis and through the lumbar vessels (open arrows). (d) Transverse CT scan obtained at 3-month follow-up demonstrates a persistent caudal leak (arrow) ventral to the prosthesis. (e) Coronal CT scan shows the introduction of a coaxial catheter past the right limb of the prosthesis into the leak (curved arrow), with filling of the left lumbar branch (straight open arrow). Note that the proximal extravasation on the right has been occluded (straight solid arrow). (f) Final coronal angiogram obtained after complete embolization of the lumbar branches and the aneurysmal sac shows the sealed prosthesis (arrows), without perigraft extravasation of contrast medium.
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Figure 2f. (a) Transverse CT scan obtained after implantation of a prosthesis in an 80-year-old male patient shows a large leak (straight arrow) ventral to the prosthesis (curved arrow). (b) Lateral aortogram shows a ventral collection of contrast medium (open arrow) fed by the site of the leak (solid arrow). (c) Coronal selective angiogram obtained after the introduction of a 5-F selective catheter into the site of the leak shows a broad outflow of contrast medium (solid arrows) around the right limb of the prosthesis and through the lumbar vessels (open arrows). (d) Transverse CT scan obtained at 3-month follow-up demonstrates a persistent caudal leak (arrow) ventral to the prosthesis. (e) Coronal CT scan shows the introduction of a coaxial catheter past the right limb of the prosthesis into the leak (curved arrow), with filling of the left lumbar branch (straight open arrow). Note that the proximal extravasation on the right has been occluded (straight solid arrow). (f) Final coronal angiogram obtained after complete embolization of the lumbar branches and the aneurysmal sac shows the sealed prosthesis (arrows), without perigraft extravasation of contrast medium.
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Figure 3a. (a) Coronal aortogram in a 66-year-old male patient shows a leak (arrow) after endovascular repair of an aortic aneurysm at the origin of the inferior mesenteric artery. (b) Coronal angiogram in the same patient after embolization with multiple minicoils shows complete occlusion (small arrow) of the leak at the origin of the inferior mesenteric artery. The coaxial catheter has been advanced through the Riolan anastomosis into the aneurysmal sac. Note that the patient underwent successful embolization (large arrow) of a prior proximal perigraft leak.
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Figure 3b. (a) Coronal aortogram in a 66-year-old male patient shows a leak (arrow) after endovascular repair of an aortic aneurysm at the origin of the inferior mesenteric artery. (b) Coronal angiogram in the same patient after embolization with multiple minicoils shows complete occlusion (small arrow) of the leak at the origin of the inferior mesenteric artery. The coaxial catheter has been advanced through the Riolan anastomosis into the aneurysmal sac. Note that the patient underwent successful embolization (large arrow) of a prior proximal perigraft leak.
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CT is substantially more sensitive than aortography for the detection of leaks, which were identified with conventional angiography in only 65% of our patients. The site and configuration of the leak very often permit precise determination of the cause and source of the leak, such that CT can be used in road mapping for transarterial embolization (10). At the time this article was published, our angiography protocol had been changed because of the exact information derived from CT; therefore, only the suspected artery is examined at angiography.
It is probable that endovascular leaks possess not only a vessel by which they are fed but also an artery that permits outflow; otherwise, a slow process of thrombosis would be expected. However, many small endovascular leaks remain open over many months. Selective angiography of the aneurysmal sac often can be used to identify the vessel responsible for vascular outflow, although these escape detection at nonselective aortography (11). This underscores the danger that, despite proximal occlusion of an artery known to supply a given leak, the leak still may be supplied by other tributaries. Recently, such considerations have led us to embolize not only the visualized feeder artery but also the total patent aneurysmal sac to prevent collateralization through other vessels.
This mechanism also would explain the existence of so-called double leaks in several of our patients, in whom adequate perigraft embolization without occlusion of the remaining aneurysmal sac was followed by a refilling of the aneurysm by other feeder arteries. In such patients, a second embolization of the supplying artery was required.
Because the reduction in the size of the aneurysm after endovascular therapy is limited even in the absence of leaks, the hemodynamic significance of an endovascular leak cannot immediately be determined from findings at CT. Blum et al (1) suggest that, in the first 12 months, a size reduction of only 2–4 mm is to be expected, while, in the next 24 months, a more pronounced reduction of 5–15 mm may be observed. Malina et al (7) point out that even minor leaks or collateral perfusion inhibit the reduction of aneurysmal diameter seen in patients with totally sealed aneurysms of the abdominal aorta (9).
In 1996, Resnikoff et al (12) studied 831 patients who underwent nonresective treatment of infrarenal abdominal aortic aneurysms with proximal and distal ligation of the aneurysmal sac combined with aortic bypass and reported on 17 patients (2%) with retrograde endovascular leaks that were fed by the lumbar, internal iliac, inferior mesenteric, or common iliac arteries. In these patients, there was a high rate of rupture of more than 40% (17 of 41) occurring within the follow-up period. These data underscore the importance of adequate therapy for endovascular leaks.
Since no confirmed results to our knowledge indicate the opposite, it has been the practice of our radiology department to recommend the treatment of all endovascular leaks that do not spontaneously seal within the 3-month follow-up period, regardless of their cause. Interventional occlusion of the leak is possible in most patients. As a rule, embolization with metal coils is attempted first, if further stent placement is not indicated or is considered dangerous, because a refilling from feeding vessels would still be possible. This procedure, as confirmed by the literature (8), also is safe and effective in treating proximal perigraft leaks. Here, the goal is not so much closure of the perfused lumen of the aneurysmal sac but rather elimination of the source of the blood flow to prevent the blood pressure from acting against the aneurysmal wall (8). Minicoils placed over a microcatheter show a higher flexibility than large-diameter coils, but if the leak is larger and is accessible with a 4- or 5-F catheter, bigger coils may help to embolize the leak more quickly and at a lower cost.
Fluid embolization substances are much cheaper but may result in more damage to nerve tissue than extensive coil embolization (13). In theory, there is an additional risk of fluid embolization agents being carried into the lumbar arteries, which, in the worst-case scenario, might cause occlusion of the anterior spinal artery (11).
Usually, embolization of a lumbar artery is relatively easy from a technical standpoint (14). Although the irregular course of the vessels often prevents the catheter from being advanced directly into the lumbar artery, the proximal occlusion of tributaries from the iliolumbar artery on both sides may achieve thrombosis of the leak in some patients (Fig 4) (11). More difficult are those leaks in patients with an internal iliac artery unilaterally covered by a stent, in which cross-filling via collateral arteries from the contralateral internal iliac artery results in reflux reperfusion of the aneurysm (11).
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Figure 4a. (a) Transverse CT scan in a 78-year-old male patient shows a small endovascular leak (arrow) supplied by a lumbar artery. (b) The aortogram (not shown) was negative, but this superselective coronal angiogram of the iliolumbar artery from the internal iliac artery demonstrates the leak (arrows). (c) Coronal selective angiogram shows complete occlusion of the leak after embolization of the iliolumbar artery (arrow), which was proved also with CT and with color duplex flow imaging.
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Figure 4b. (a) Transverse CT scan in a 78-year-old male patient shows a small endovascular leak (arrow) supplied by a lumbar artery. (b) The aortogram (not shown) was negative, but this superselective coronal angiogram of the iliolumbar artery from the internal iliac artery demonstrates the leak (arrows). (c) Coronal selective angiogram shows complete occlusion of the leak after embolization of the iliolumbar artery (arrow), which was proved also with CT and with color duplex flow imaging.
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Figure 4c. (a) Transverse CT scan in a 78-year-old male patient shows a small endovascular leak (arrow) supplied by a lumbar artery. (b) The aortogram (not shown) was negative, but this superselective coronal angiogram of the iliolumbar artery from the internal iliac artery demonstrates the leak (arrows). (c) Coronal selective angiogram shows complete occlusion of the leak after embolization of the iliolumbar artery (arrow), which was proved also with CT and with color duplex flow imaging.
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In patients with refilling of the aneurysm through the inferior mesenteric artery, the endovascular leak can be embolized via the superior mesenteric artery. In the absence of the Riolan anastomosis, the almost-always-identifiable marginal artery may be used to access the inferior mesenteric artery (15).
The prospects for angiography are especially unfavorable in patients in whom an internal iliac artery has been covered by a stent, because a leak on this side is fed by multiple collateral vessels.
It remains unclear whether embolization in proximal leaks actually reduces the pressure on the aneurysmal wall. To our knowledge, long-term results also are lacking for the pressure endurance of the material used in endovascular techniques. With a thickness of 0.1 mm, it is substantially thinner than surgically implanted prosthetic material (16).
Especially worrisome is the late onset of endovascular leaks. We observed two patients with late leaks that occurred with primarily sealed prostheses. One of these patients had a leak that was supplied by a lumbar artery. The second patient had a stent fracture 12 months after its placement. As has been observed by other authors, these leaks would seem to be due, at least in part, to material fatigue (4). It remains to be seen how frequently such complications actually occur and whether technical advances may result in their long-term prevention. In the first patient, selective imaging of the inferior mesenteric artery did not primarily demonstrate retrograde filling of the aneurysmal sac, although 3 months later an endovascular leak supplied by the same artery was detected and was successfully embolized. Three months before selective imaging, a proximal perigraft leak was occluded, but the aneurysmal sac was not embolized.
Long-term importance accrues to conventional radiography in multiple projections, which appears to be very sensitive in depicting rupture of the stent mesh (10). This is particularly true in material fatigue, which may occur in patients with long-term follow-up. These findings often are identified much less exactly at angiography or at CT, which often show nothing more than a large leak (Fig 5) (10).
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Figure 5a. (a) Twenty-five-degree left anterior oblique angiogram in a 63-year-old male patient with traumatic pseudoaneurysm of the thoracic aorta after implantation of a tube prosthesis shows diffuse perigraft contrast medium extravasation (open arrows) and relative stenosis (solid arrows) at the lower end of the aneurysm. The cause of the leak is not apparent. (b) Transverse CT scan shows strong crimping of the stent mesh, with collapsed configuration of the prosthesis. The cause of the leak also was not apparent at this examination, but fluoroscopy showed a disconnection of the graft mesh, which pointed to rupture of the stent mesh. These findings were confirmed during surgical replacement of the graft.
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Figure 5b. (a) Twenty-five-degree left anterior oblique angiogram in a 63-year-old male patient with traumatic pseudoaneurysm of the thoracic aorta after implantation of a tube prosthesis shows diffuse perigraft contrast medium extravasation (open arrows) and relative stenosis (solid arrows) at the lower end of the aneurysm. The cause of the leak is not apparent. (b) Transverse CT scan shows strong crimping of the stent mesh, with collapsed configuration of the prosthesis. The cause of the leak also was not apparent at this examination, but fluoroscopy showed a disconnection of the graft mesh, which pointed to rupture of the stent mesh. These findings were confirmed during surgical replacement of the graft.
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In our patient group, a graft rupture did occur in a patient with an aneurysm of the thoracic aorta and may have been due to the advancement of the prosthesis during implantation. At the aortic arch in particular, the relatively rigid implantation instrument must be advanced into the curvature of the arch, at which point the material approaches the limits of its endurance. This was the only patient in our series in whom elective open revision was performed weeks after the initial endovascular procedure.
Successful interventional therapy of perigraft leaks after endovascular extirpation of aortic aneurysms is possible in a majority of patients. In our experience, these procedures are associated with no major complications or adverse effects. It remains to be seen whether successful embolization leads in the long term to shrinkage of the aneurysmal sac and to a reduced risk of rupture.
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Footnotes
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Author contributions: Guarantors of integrity of entire study, J.G., N.R.; study concepts, J.G., R.P.; study design, R.S., S.C.K.; definition of intellectual content, H.J.B., W.K.; literature research, A.S.; clinical studies, S.C.K.; data acquisition, C.E., J.S.; data analysis, J.S.; manuscript preparation, J.G., N.R., R.S.; manuscript editing, S.K., A.S.; manuscript review, L.S.P., H.J.B., W.K.
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Abstract
Introduction
