AJR 2000; 174:811-814
© American Roentgen Ray Society
Angiography of Leaks After Endovascular Repair of Infrarenal Aortic Aneurysms
Johannes Görich1,
Norbert Rilinger1,
Stefan Krämer1,
Roman Sokiranski1,
Reinhard Pamler2,
Cengiz Ermis1 and
Xaver Kapfer2
1
Department of Radiology, University of Ulm, Steinhoevelstra. 9, 89075 Ulm,
Germany
2
Department of Thoracic and Vascular Surgery, University of Ulm, 89075 Ulm,
Germany.
Received March 19, 1999;
accepted after revision August 31, 1999.
Address correspondence to J. Görich.
Abstract
OBJECTIVE. We examined whether leaks that persist after stent
grafting are associated with outflow arteries.
SUBJECTS AND METHODS. Selective angiography was performed in 21
patients with persistent leaks after undergoing endovascular repair of
infrarenal aneurysms of the abdominal aorta. Late leaks occurred in five
patients whose prostheses were originally sealed. Before angiography, the size
and position of leaks were determined with CT and color Doppler
sonography.
RESULTS. Superselective angiography was successful in 19 of 21
patients. In two patients, angiography was performed over the afferent artery
supplying the leak. We found one outflow artery at the site of the leak in 10
patients (47%); two outflow arteries in five (23.8%); and as many as five
outflow arteries in three (14%). Angiography overlooked outflow arteries in
three patients (14%). The lumbar and inferior mesenteric, urethral, and
testicular arteries were identified as outflow arteries.
CONCLUSION. Other than feeder arteries, persistent leaks are
associated with outflow vessels that contribute to the patency of leaks.
Introduction
Research shows that the incidence of leaks after endovascular repair of
infrarenal aortic aneurysms ranges from 2.4% to more than 44%
[1,2].
Leaks originate at the proximal and distal ends of grafts. Such leaks
represent perigraft leaks according to the classification of White et al.
[1]. Reperfusion of the
aneurysmal sac may occur via the lumbar, sacral, gonadal, accessory renal, or
inferior mesenteric arteries (endoleaks). Of these, about 50% thrombose
spontaneously and some cause aortic rupture
[3]. After 6 months, the
spontaneous closure of leaks is rare
[4].
Persistent leaks probably possess an entry (i.e., feeder or afferent
vessels) by which they are supplied, and an exit (i.e., efferent or outflow
vessels) permitting outflow; otherwise, a slow process of thrombosis would
occur. Even small leaks remain open over many months. We report our
angiographic findings in 21 patients with leaks.
Subjects and Methods
Sixty-seven patients (five women, 62 men) ranging in age from 26 to 88
years (average age, 68 years) underwent transfemoral insertion of endoluminal
stent-grafts for the treatment of infrarenal aortic aneurysms. Tube protheses
were implanted in six patients and bifurcated stent-grafts in 61 patients.
Different devices were used: Vanguard grafts (Boston Scientific, Hilden,
Germany) in 34 patients, Corvita grafts (Corvita Europe, Brussels, Belgium) in
eight patients, Talent grafts (Hosmed,
Oberhaching-München, Germany) in 18 patients,
Gore grafts (W. L. Gore, Putzbrunn, Germany) in six patients, and AneuRX
grafts (Medtronic, Düsseldorf, Germany) in one
patient.
To monitor the protheses' position and seal, a three-phase helical CT
examination was performed in the first week after implantation and then every
3 months. The parameters for unenhanced CT were pitch, 1.5; slice thickness,
8.8 mm (effective); increment, 10 mm. The parameters for enhanced CT were
pitch, 1; slice thickness, 5.5 mm; increment, -2.5 mm; caudiocranial; contrast
medium, 150 ml; flow rate, 2.5 ml/sec; delay, 45 sec. Additional late slices
were obtained at 100 sec; pitch, 1.5; slice thickness, 5.5 mm; increment, 2.5
mm. All scanning was performed with the Elscint Twin scanner (Picker,
Hofheim-Wallau, Germany). In 56 patients, color duplex sonography (Logig 500;
Kranzbühler, Solingen, Germany) was performed as
an adjunct procedure.
In patients with leaks having a duration of at least 3 months,
intraarterial angiography was performed within 2 days. Patients underwent
abdominal aortography in at least two planes (30 ml of contrast material at a
flow of 12 ml/sec, long series to detect late leaks); angiography with the
Cobra or Sidewinder catheter (Mallinckrodt, Hennef, Germany) at the proximal
end of the prothesis; and visualization of the internal iliac artery
bilaterally (with a manual injection of 10 ml of contrast medium) and the
superior mesenteric artery (using 25 ml of contrast medium [300 mg/ml] at a
flow rate of 5 ml/sec).
We used the findings of CT and color duplex sonography to locate leaks with
angiography. The angiography catheter was advanced as far as possible into the
leak. We used a coaxial catheter (Tracker 18, Rehaforum, Cologne, Germany; or
Rapid Transit, Cordis, Haan, Germany) in 16 patients. Once the catheter was
positioned, angiography was performed using 3-10 ml of contrast medium. After
viewing the leak, we performed an interventional occlusive procedure (stent or
embolization).
Although sizes were not exactly quantified, we estimated the volume of
leaks using CT. The maximum extent of the leak was measured in the
x-, y-, and z-axes and then multiplied by a factor
of 0.5. We used the Student's t test to determine statistical
results.
Results
Twenty-one (31%) of 67 patients had leaks after the endovascular repair of
their aortic aneurysms (Table
1); five patients had late leaks occurring in originally sealed
protheses. In 19 patients, we performed superselective angiography with the
tip of the catheter in the aneurysmal sac. In two patients, we could not
access the leak because of the small diameter of the supplying artery (one
patient) or the tortuous course of the vessel (one patient); in these
patients, we performed subselective leakography with the catheter tip in the
afferent artery. Eight patients had one outflow artery; five patients had two;
and three patients had more than three
(Table 2). Angiography
overlooked outflow arteries in three patients. There was no significant
difference between perigraft leaks (type I, according to the classification of
White et al. [1]) and endoleaks
(type II, according to the classification of White et al.) from the efferent
arteries (Table 3). We
determined that larger leaks (9.9 ± 4.9 cm3 versus 0.9
± 0.3 cm3) had significantly (p < 0.0004) more
outflow arteries (2.5 ± 1.6 cm3 versus 1.5 ± 0.8
cm3) than smaller leaks. All larger leaks were located at the
proximal end of the endoprothesis.
Aortography overlooked five (24%) of 21 leaks detected on CT and duplex
sonography; however, the leaks were revealed on superselective
angiography.
Discussion
The pathophysiologic significance of leaks is not well understood. Some
data suggest that perigraft leaks and endoleaks, if persistent, may be
associated with an increased risk of rupture
[2,
3]. The hemodynamic
significance of leaks cannot be immediately determined from CT because the
reduction in the size of aneurysms after endovascular therapy is limited even
without leaks. Blum et al. [5]
suggest that a size reduction of 2-4 mm may occur during the first year, and a
size reduction of 5-15 mm may occur during the second year. Malina et al.
[6] suggest that even minor
leaks inhibit the reduction of aneurysm diameter in patients with totally
excluded aneurysms of the abdominal aorta. Matsumura and Moore
[7] suggest that patients with
a continuing periprosthetic leak have an average aneurysm sac enlargement of
0.1 cm/year. They reported that, in patients with persistent leaks, aneurysms
enlarge at a rate considerably slower than that expected in patients with
untreated aneurysms, suggesting that endovascular repair may provide some
hemodynamic benefit. This conclusion is speculative because, to our knowledge,
comparison studies have not been published, and the risk of rupture of an
aneurysm more than 5 cm in diameter is not strictly related to size. A study
by Resch et al. [8] reported an
8-mm postoperative median decrease in aortic diameter in patients without
leaks. Additionally, they reported that patients with endoleaks showed no
statistically significant change in aortic diameter at follow-up, and patients
with endoleaks that had stopped showed a 1- to 12-mm decrease in aortic
diameter.
A report by Resnikoff et al.
[9] studied 831 patients
undergoing nonresectable treatment of infrarenal aneurysms of the abdominal
aorta with proximal and distal ligation of the aneurysm sac and aortic bypass.
They reported 17 retrograde endoleaks (2%) fed by the lumbar, hypogastric,
iliac, and inferior mesenteric arteries. During the follow-up examination,
Resnikoff et al. noted a high rate of rupture. All these studies
[7,8,9]
support the hypothesis that persistent leaks are associated with an unknown
risk of rupture. In our study, all superselective leakographies visualized at
least one (Figs. 1 and
2), though usually more than
two, efferent vessels, including vessels that were difficult to selectively
catheterize (e.g., testicular [Fig.
3] and urethral vessels). Therefore, it is conceivable that, after
implantation of prostheses, spontaneous occlusion of leaks may be caused by
the lack of efferent arteries; whereas, leaks with outflow vessels may be
predisposed to persistence. Hence, embolization should be directed to a
generous and central occlusion of the leak to prevent persistence sustained by
other arteries. In a study by Wain et al.
[2], aneurysms with neck
lengths of 2 cm or less, those with severe neck calcifications, and those with
patent aneurysm side branches were associated with a higher rate of endoleaks.
In contrast to our findings, the endoleaks in the study by Wain et al. had
outflow arteries in only 29% of patients. Our superselective examination of
leaks may be responsible for the detection of outflow arteries in 86% of our
patients (Fig. 4). Lack of
direct access to the leak and poor positioning of the catheter may interfere
with contrast enhancement of efferent arteries. In our series, CT was more
sensitive than aortography in detecting leaks (aortography revealed leaks in
<80% of patients). The site and configuration of leaks help to determine
the cause and source of leaks; therefore, CT findings can be used to locate
leaks with superselective angiographic control and embolization.
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Fig. 1. —69-year-old man with Vanguard bifurcated graft (Boston Scientific,
Hilden, Germany). Subselective angiogram shows endoleak is supplied by
inferior mesenteric artery via superior mesenteric artery. Note arc of Riolan
(open arrows) and outflow of leak (solid arrow) through
right-sided lumbar artery.
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Fig. 2. —59-year-old man with Talent graft (Hosmed,
Oberhaching-München, Germany). Superselective
leakography via coaxial catheter (Rapid Transit; Cordis, Haan, Germany)
reveals outflow of perigraft leak from lumbar artery (arrow).
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Fig. 3. —75-year-old patient with bifurcated graft (Corvita Europe, Brussels,
Belgium). Superselective leakography of right-sided distal perigraft leak
reveals multiple efferent arteries: right testicular artery (open
arrows), left lumbar artery (solid straight arrow), inferior
mesenteric artery (curved arrow), and median sacral artery
(arrowheads).
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Fig. 4. —79-year-old man with dorsolateral endoleak from Talent bifurcated
stent graft (Hosmed, Oberhaching-München,
Germany). Leak (solid arrows) is supplied by collaterals from
iliolumbar artery. No superselective access was possible because of small
diameter of supplying vessels. Note outflow through right-sided lumbar artery
(open arrow).
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In conclusion, leaks after endovascular repair of aortic aneurysms have an
outflow artery in most patients; in our study, 10 patients (48%) had two or
more efferent arteries. Embolization for leak occlusion should focus on the
supplying artery and potential efferent vessels to prevent leak persistence
through other tributaries.
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Abstract
Introduction
