- Email: [email protected]
Dilatation of the Proximal Neck of Infrarenal Aortic Aneurysms after Endovascular AAA Repair
Eur J Vasc Endovasc Surg 19, 197–201 (2000) doi:10.1053/ejvs.1999.0988, available online at http://www.idealibrary.com on
Dilatation of the Proximal Neck of Infrarenal Aortic Aneurysms after Endovascular AAA Repair J. J. Wever1, A. J. de Nie1, J. D. Blankensteijn∗1, I. A. M. J. Broeders1, W. P. Th. M. Mali2 and B. C. Eikelboom1 Departments of 1Vascular Surgery and 2Radiology, University Medical Center, Utrecht, The Netherlands Objectives: to assess size changes of the proximal aortic neck after endograft placement. Methods: since 1994, 54 consecutive patients have undergone abdominal aortic aneurysm (AAA) repair with the Endovascular Technologies (EVT) endograft. The study group comprised the 33 patients who had completed at least six months of the prospective follow-up protocol. The pre-, postoperative and follow-up helical computed tomography (CT) angiograms (CTAs) were processed on a workstation. The proximal neck dimensions were measured perpendicular to the central lumen line of the aortic neck. The cross-sectional area was measured at the proximal attachment system and at 1 cm proximal to the renal arteries. Results: while the dimensions of suprarenal aorta did not change, a significant dilatation of the proximal neck was found. The median increase was 10.3% at 6 months and 15.5% at 12 months. No correlation could be found between the amount of dilatation and pre- or postoperative neck-size, graft diameter and amount of graft-oversizing. Conclusion: the infrarenal aortic neck demonstrates continued dilatation during follow-up after endograft placement. Key Words: Abdominal aortic aneurysm; Endoprosthesis; Endovascular repair; Spiral computed tomography angiogram (CTA).
Introduction Long-term success after endovascular treatment of abdominal aortic aneurysms depends on durable fixation of the endograft at the proximal and distal necks. Gradual dilatation of the aorta at the level of attachment systems may cause leakage and stent migration. Studies in healthy persons have shown that the infrarenal aortic diameter increases 26% in males and 24% in females between the age of 25 and 70 years.1 After conventional abdominal aortic aneurysm (AAA) repair higher rates of increase have been described.2–5 Some studies show dilatation of the proximal aortic neck following endovascular AAA repair, but these studies were performed on axial CT slices.6–8 Proximal neck measurements performed on linear reformats perpendicular to the central lumen line are preferable. With this method the position relative to the renal arteries is not dependent on the slice thickness, and therefore the reproducibility is better. ∗ Please address all correspondence to: J. D. Blankensteijn, Department of Vascular Surgery, G.04.232, University Medical Center, PO Box 85500, 3508 GA Utrecht, The Netherlands. 1078–5884/00/020197+05 $35.00/0 2000 Harcourt Publishers Ltd.
This study was performed to assess size changes of the supra- and infrarenal aorta after endovascular aneurysm exclusion, as measured along the central lumen line on spiral CTA scans.
Patients and Methods From January 1994 until November 1998, 54 consecutive patients underwent endovascular treatment of an infrarenal aortic aneurysm, using the EVT Endograft (Guidant, Menlo Park, CA, U.S.A.). Postoperatively, all patients were subjected to contrastenhanced computed tomography (CTA) scanning at discharge, 6 months, 12 months and yearly thereafter. In 21 patients follow-up was less than 6 months due to operative mortality in one, non-related mortality in one, conversion in six and duration in 10, while three patients were followed in another hospital. The remaining 33 patients were included in the study. In these patients, 11 tube, 19 bifurcated and three aortoiliac endografts were implanted. There were four female and 29 male patients. The median age was 69 years (IQ range 63–73).
198
J. J. Wever et al.
Table 1. Median cross-sectional area (IQ range) during follow-up in mm2.
Proximal neck Suprarenal
Postoperative (n=33)
6 months (n=33)
12 months (n=24)
346 (292–379) 378 (340–423)
365 (321–418)∗ 397 (309–439)∗ 399 (331–440) 390 (342–442)
∗ p<0.01 Wilcoxon rank.
Table 2. Median of the individual changes (IQ range) compared to the postoperative value. 6 months (n=33)
12 months (n=24)
Proximal neck +10.3% (+4.9%–+15.1%) +15.5% (+11.7–+24.4%) Suprarenal +1.1% (−4.5%–+5.4%) −3.2% (−6.9%–+4.1%) Fig. 1. Drawing of the contour on the linear reformats. The cut-plane is always perpendicular to the vessel axis, providing a reproducible measurement.
Preoperative, postoperative and follow-up contrastenhanced CT images were reviewed on an Easy Vision workstation (Philips Medical Systems, Best, The Netherlands) to determine changes in cross-sectional area of the abdominal aorta at the levels indicated below. All measurements were taken perpendicular to the central lumen line.9–12 Proximal neck dimensions were measured 1 cm below the most distal renal artery. On the preoperative scans, a contour was drawn outlining the aorta. On the postoperative scans this level allowed measuring the neck in the proximal attachment system, and the contour was drawn through the hooks (Fig. 1). The suprarenal aortic dimensions were measured in the same manner at 1 cm above the most proximal renal artery. For statistical analysis the Wilcoxon rank test was used to assess significance of postoperative and followup size changes. Correlation between the amount of dilatation and pre- and postoperative neck-size, graft diameter and amount of graft-oversizing was calculated using Spearman’s test. A value of p<0.05 was considered statistically significant. All values are given as median and quartile range or as individual values.
Results The 6-month, 1-, 2-, 3- and 4-year follow-up scans were available in 33, 24, nine, five and three patients respectively. Median follow-up was 12 months (range Eur J Vasc Endovasc Surg Vol 19, Month 2000
6–48). The median cross-sectional area showed a significant increase at the level of the proximal attachment system from 346 (292–379) mm2 to 365 (321–417) mm2 at 6 months (p<0.01) and to 397 (309–438) mm2 at 12 months (p<0.01) compared to the postoperative area (Table 1). The median increase between 6 and 12 months was also statistically significant (p<0.05). The median of the individual changes was +10.3% after 6 months and +15.5% after 12 months. These results are shown in Table 2. The size changes at the level of the proximal attachment system in the individual patients are shown in Fig. 2. All but two patients showed an increasing cross-sectional area during follow-up, compared to the first postoperative measurement. In three patients, four years of CTA follow-up was available demonstrating an increased neck-size of 11.1%, 21.5% and 24.9% at 24, 36 and 48 months, respectively. The suprarenal aorta did not show significant growth (p>0.4) (Fig. 3). The individual neck-sizes on the first postoperative scans were all smaller than the nominal (maximal) size of the implanted stent graft, due to intentional graft-oversizing. The median ratio of oversizing was 1.13 (1.07–1.31). The amount of dilatation did not correlate with preoperative necksize (r=−0.12, p=0.50), postoperative neck-size (r= −0.25, p=0.16), nominal graft diameter (r=0, p=1.00) or attachment system oversize (r=0.08, p=0.67). No correlation with the presence of early (r=−0.09, p= 0.59, n=14) or late endoleak (r=0.06, p=0.74, n=8) could be demonstrated. Secondary endoleak or migration was not encountered in the studied patient group.
Proximal Neck Dilatation after Endovascular AAA Repair
199
Fig. 2. Cross-sectional area at the proximal aortic neck in the 33 patients. Size in square millimetres is indicated on the vertical axis, and follow-up interval for each patient is indicated on the horizontal axis.
Discussion The postoperative scan data demonstrate significant proximal neck dilatation at 6 and 12 months after endovascular AAA repair. Comparison to the preoperative scans was not performed because aortic neck measurements with or without an EVT endograft in place are difficult to compare. The reason for this is that artefacts caused by the stent material prevent measurement of the aortic wall. Therefore, the area within the stent was measured. For obvious reasons, this measurement was not available from the preoperative scans. The use of a workstation allowed measuring crosssectional areas. Other groups have studied the changes in diameter and circumference but the reproducibility of these measurements is limited in case of irregular contours of the proximal neck. Using callipers, Sonesson et al.6 measured diameters on axial CT planes in 31 patients treated with a home-made stent graft. They found a significant mean increase of 1.7 mm at the last available follow-up scan compared to the preoperative neck-size. In addition an insignificant mean increase of the suprarenal aorta was found. In the study of
Matsumura et al.,13 no significant proximal neck growth was demonstrated at 12 months. In their study, 34 patients with an EVT endograft were analysed using axial diameter measurements. One year later, the same authors reported on a larger group of patients (n=59) and showed a mean increase of 0.7 and 0.9 mm in proximal neck diameter after 1 and 2 years respectively.7 May et al.8 reported on increasing proximal neck diameters when comparing the preoperative values with the postoperative ones, but no progressive increase at 6, 12 and 18 months. The diameters were measured 1 cm below the renal arteries on axial CT slices. They found no increase in aortic diameter at the level of the coeliac trunk. The above-mentioned studies are difficult to compare, as various stent-graft designs were used. Two possible explanations can be given for continued growth of the infrarenal neck after endovascular AAA repair. It is either a continuation of the aneurysmal disease process or an effect of the outward force generated by the endovascular stent onto the infrarenal aortic wall. Although it is most probably a combination of these two factors, it is interesting to discuss these issues separately, as the proximal attachment mechanisms vary Eur J Vasc Endovasc Surg Vol 19, Month 2000
200
J. J. Wever et al.
Fig. 3. Cross-sectional area at the suprarenal aortic neck in the 33 patients. Size in square millimetres is indicated on the vertical axis, and follow-up interval for each patient is indicated on the horizontal axis.
between the available stent-graft designs. If the outward force is the predominant cause of postoperative neck dilatation, the diameter will probably not stretch beyond the nominal (maximal) stent-size. But as the stent approaches its maximal size, the friction forces between stent and aortic wall may become dangerously low, with possible stent migration as a result. The preferred graft attachment design from this perspective would consist of a stent with low outward force to prevent accelerated dilatation and a fixation mechanism independent of friction forces between stent and neck (i.e. hooks). If progressive enlargement is merely a consequence of the underlying aneurysmal disease, the oversizing of the stent graft relative to the neck-size actually allows the stent to adapt to the neck dilatation. In this scenario, high outward force would not necessarily be detrimental to the neck. Although it may take a longer period of time, the end-result of continued neck dilatation in the presence of a stent with a limit to its diameter will ultimately be the same: potential graft migration if no other fixation mechanisms are present. In addition, dilatation beyond the nominal stent size may create a secondary attachment site leak, even without stent migration. Eur J Vasc Endovasc Surg Vol 19, Month 2000
Initial dilatation due to the procedure without subsequent dilatation cannot be considered an adequate explanation, as the increase of the proximal neck area was statistically significant for both the first and second 6 months’ follow-up interval. No significant increase of the suprarenal aorta was found in our study. Although this provides some support of the theory that progression of disease is not the only factor, it must be realised that the infrarenal aorta has a less dense fibre structure when compared to the suprarenal aorta.14 No correlation could be found between the presence or absence of endoleaks, pre- and postoperative neck-size, graft diameter and amount of graft oversize, probably due to small numbers. In conclusion, the infrarenal aortic neck demonstrates continued dilatation after endograft placement.
References 1 Sonesson B, Lanne T, Hansen F, Sandgren T. Infrarenal aortic diameter in the healthy person. Eur J Vasc Surg 1994; 8: 89–95. 2 Lipski DA, Ernst CB. Natural history of the residual infrarenal
Proximal Neck Dilatation after Endovascular AAA Repair
3 4 5 6 7
8
aorta after infrarenal abdominal aortic aneurysm repair. J Vasc Surg 1998; 27: 805–811. Illig KA, Green RM, Ouriel K et al. Fate of the proximal aortic cuff: implications for endovascular aneurysm repair. J Vasc Surg 1997; 26: 492–499. Curl GR, Faggioli GL, Stella A, D’Addato M, Ricotta JJ. Aneurysmal change at or above the proximal anastomosis after infrarenal aortic grafting. J Vasc Surg 1992; 16: 855–859. Sonesson B, Resch T, Lanne T, Ivancev K. The fate of the infrarenal aortic neck after open aneurysm surgery. J Vasc Surg 1998; 28: 889–894. Sonesson B, Malina M, Ivancev K et al. Dilatation of the infrarenal aneurysm neck after endovascular exclusion of abdominal aortic aneurysm. J Endovasc Surg 1998; 5: 195–200. Matsumura JS, Chaikof EL. Continued expansion of aortic necks after endovascular repair of abdominal aortic aneurysms. EVT Investigators. EndoVascular Technologies, Inc. J Vasc Surg 1998; 28: 422–430. May J, White G, Yu W et al. A prospective study of anatomicopathological changes in abdominal aortic aneurysms following endoluminal repair: is the aneurysmal process reversed? Eur J Vasc Endovasc Surg 1996; 12: 11–17.
201
9 Balm R, Eikelboom BC, van Leeuwen MS, Noordzij J. Spiral CT-angiography of the aorta. Eur J Vasc Surg 1994; 8: 544–551. 10 Broeders IA, Blankensteijn JD, Olree M, Mali W, Eikelboom BC. Preoperative sizing of grafts for transfemoral endovascular aneurysm management: a prospective comparative study of spiral CT angiography, arteriography, and conventional CT imaging. J Endovasc Surg 1997; 4: 252–261. 11 Balm R, van Leeuwen MS, Noordzij J et al. Spiral CT for aortic aneurysms. In: Greenhalgh RM, eds. Vascular Imaging for Surgeons. W. B. Saunders Co Ltd., 1995: 191–202. 12 Balm R, Kaatee R, Blankensteijn JD, Mali WP, Eikelboom BC. CT-angiography of abdominal aortic aneurysms after transfemoral endovascular aneurysm management. Eur J Vasc Endovasc Surg 1996; 12: 182–188. 13 Matsumura JS, Pearce WH, McCarthy WJ, Yao JS. Reduction in aortic aneurysm size: early results after endovascular graft placement. EVT Investigators. J Vasc Surg 1997; 25: 113–123. 14 Wolinsky H. Comparison of medial growth of human thoracic and abdominal aortas. Circ Res 1970; 27: 531–538. Accepted 13 August 1999
Eur J Vasc Endovasc Surg Vol 19, Month 2000
Dilatation of the Proximal Neck of Infrarenal Aortic Aneurysms after Endovascular AAA Repair J. J. Wever1, A. J. de Nie1, J. D. Blankensteijn∗1, I. A. M. J. Broeders1, W. P. Th. M. Mali2 and B. C. Eikelboom1 Departments of 1Vascular Surgery and 2Radiology, University Medical Center, Utrecht, The Netherlands Objectives: to assess size changes of the proximal aortic neck after endograft placement. Methods: since 1994, 54 consecutive patients have undergone abdominal aortic aneurysm (AAA) repair with the Endovascular Technologies (EVT) endograft. The study group comprised the 33 patients who had completed at least six months of the prospective follow-up protocol. The pre-, postoperative and follow-up helical computed tomography (CT) angiograms (CTAs) were processed on a workstation. The proximal neck dimensions were measured perpendicular to the central lumen line of the aortic neck. The cross-sectional area was measured at the proximal attachment system and at 1 cm proximal to the renal arteries. Results: while the dimensions of suprarenal aorta did not change, a significant dilatation of the proximal neck was found. The median increase was 10.3% at 6 months and 15.5% at 12 months. No correlation could be found between the amount of dilatation and pre- or postoperative neck-size, graft diameter and amount of graft-oversizing. Conclusion: the infrarenal aortic neck demonstrates continued dilatation during follow-up after endograft placement. Key Words: Abdominal aortic aneurysm; Endoprosthesis; Endovascular repair; Spiral computed tomography angiogram (CTA).
Introduction Long-term success after endovascular treatment of abdominal aortic aneurysms depends on durable fixation of the endograft at the proximal and distal necks. Gradual dilatation of the aorta at the level of attachment systems may cause leakage and stent migration. Studies in healthy persons have shown that the infrarenal aortic diameter increases 26% in males and 24% in females between the age of 25 and 70 years.1 After conventional abdominal aortic aneurysm (AAA) repair higher rates of increase have been described.2–5 Some studies show dilatation of the proximal aortic neck following endovascular AAA repair, but these studies were performed on axial CT slices.6–8 Proximal neck measurements performed on linear reformats perpendicular to the central lumen line are preferable. With this method the position relative to the renal arteries is not dependent on the slice thickness, and therefore the reproducibility is better. ∗ Please address all correspondence to: J. D. Blankensteijn, Department of Vascular Surgery, G.04.232, University Medical Center, PO Box 85500, 3508 GA Utrecht, The Netherlands. 1078–5884/00/020197+05 $35.00/0 2000 Harcourt Publishers Ltd.
This study was performed to assess size changes of the supra- and infrarenal aorta after endovascular aneurysm exclusion, as measured along the central lumen line on spiral CTA scans.
Patients and Methods From January 1994 until November 1998, 54 consecutive patients underwent endovascular treatment of an infrarenal aortic aneurysm, using the EVT Endograft (Guidant, Menlo Park, CA, U.S.A.). Postoperatively, all patients were subjected to contrastenhanced computed tomography (CTA) scanning at discharge, 6 months, 12 months and yearly thereafter. In 21 patients follow-up was less than 6 months due to operative mortality in one, non-related mortality in one, conversion in six and duration in 10, while three patients were followed in another hospital. The remaining 33 patients were included in the study. In these patients, 11 tube, 19 bifurcated and three aortoiliac endografts were implanted. There were four female and 29 male patients. The median age was 69 years (IQ range 63–73).
198
J. J. Wever et al.
Table 1. Median cross-sectional area (IQ range) during follow-up in mm2.
Proximal neck Suprarenal
Postoperative (n=33)
6 months (n=33)
12 months (n=24)
346 (292–379) 378 (340–423)
365 (321–418)∗ 397 (309–439)∗ 399 (331–440) 390 (342–442)
∗ p<0.01 Wilcoxon rank.
Table 2. Median of the individual changes (IQ range) compared to the postoperative value. 6 months (n=33)
12 months (n=24)
Proximal neck +10.3% (+4.9%–+15.1%) +15.5% (+11.7–+24.4%) Suprarenal +1.1% (−4.5%–+5.4%) −3.2% (−6.9%–+4.1%) Fig. 1. Drawing of the contour on the linear reformats. The cut-plane is always perpendicular to the vessel axis, providing a reproducible measurement.
Preoperative, postoperative and follow-up contrastenhanced CT images were reviewed on an Easy Vision workstation (Philips Medical Systems, Best, The Netherlands) to determine changes in cross-sectional area of the abdominal aorta at the levels indicated below. All measurements were taken perpendicular to the central lumen line.9–12 Proximal neck dimensions were measured 1 cm below the most distal renal artery. On the preoperative scans, a contour was drawn outlining the aorta. On the postoperative scans this level allowed measuring the neck in the proximal attachment system, and the contour was drawn through the hooks (Fig. 1). The suprarenal aortic dimensions were measured in the same manner at 1 cm above the most proximal renal artery. For statistical analysis the Wilcoxon rank test was used to assess significance of postoperative and followup size changes. Correlation between the amount of dilatation and pre- and postoperative neck-size, graft diameter and amount of graft-oversizing was calculated using Spearman’s test. A value of p<0.05 was considered statistically significant. All values are given as median and quartile range or as individual values.
Results The 6-month, 1-, 2-, 3- and 4-year follow-up scans were available in 33, 24, nine, five and three patients respectively. Median follow-up was 12 months (range Eur J Vasc Endovasc Surg Vol 19, Month 2000
6–48). The median cross-sectional area showed a significant increase at the level of the proximal attachment system from 346 (292–379) mm2 to 365 (321–417) mm2 at 6 months (p<0.01) and to 397 (309–438) mm2 at 12 months (p<0.01) compared to the postoperative area (Table 1). The median increase between 6 and 12 months was also statistically significant (p<0.05). The median of the individual changes was +10.3% after 6 months and +15.5% after 12 months. These results are shown in Table 2. The size changes at the level of the proximal attachment system in the individual patients are shown in Fig. 2. All but two patients showed an increasing cross-sectional area during follow-up, compared to the first postoperative measurement. In three patients, four years of CTA follow-up was available demonstrating an increased neck-size of 11.1%, 21.5% and 24.9% at 24, 36 and 48 months, respectively. The suprarenal aorta did not show significant growth (p>0.4) (Fig. 3). The individual neck-sizes on the first postoperative scans were all smaller than the nominal (maximal) size of the implanted stent graft, due to intentional graft-oversizing. The median ratio of oversizing was 1.13 (1.07–1.31). The amount of dilatation did not correlate with preoperative necksize (r=−0.12, p=0.50), postoperative neck-size (r= −0.25, p=0.16), nominal graft diameter (r=0, p=1.00) or attachment system oversize (r=0.08, p=0.67). No correlation with the presence of early (r=−0.09, p= 0.59, n=14) or late endoleak (r=0.06, p=0.74, n=8) could be demonstrated. Secondary endoleak or migration was not encountered in the studied patient group.
Proximal Neck Dilatation after Endovascular AAA Repair
199
Fig. 2. Cross-sectional area at the proximal aortic neck in the 33 patients. Size in square millimetres is indicated on the vertical axis, and follow-up interval for each patient is indicated on the horizontal axis.
Discussion The postoperative scan data demonstrate significant proximal neck dilatation at 6 and 12 months after endovascular AAA repair. Comparison to the preoperative scans was not performed because aortic neck measurements with or without an EVT endograft in place are difficult to compare. The reason for this is that artefacts caused by the stent material prevent measurement of the aortic wall. Therefore, the area within the stent was measured. For obvious reasons, this measurement was not available from the preoperative scans. The use of a workstation allowed measuring crosssectional areas. Other groups have studied the changes in diameter and circumference but the reproducibility of these measurements is limited in case of irregular contours of the proximal neck. Using callipers, Sonesson et al.6 measured diameters on axial CT planes in 31 patients treated with a home-made stent graft. They found a significant mean increase of 1.7 mm at the last available follow-up scan compared to the preoperative neck-size. In addition an insignificant mean increase of the suprarenal aorta was found. In the study of
Matsumura et al.,13 no significant proximal neck growth was demonstrated at 12 months. In their study, 34 patients with an EVT endograft were analysed using axial diameter measurements. One year later, the same authors reported on a larger group of patients (n=59) and showed a mean increase of 0.7 and 0.9 mm in proximal neck diameter after 1 and 2 years respectively.7 May et al.8 reported on increasing proximal neck diameters when comparing the preoperative values with the postoperative ones, but no progressive increase at 6, 12 and 18 months. The diameters were measured 1 cm below the renal arteries on axial CT slices. They found no increase in aortic diameter at the level of the coeliac trunk. The above-mentioned studies are difficult to compare, as various stent-graft designs were used. Two possible explanations can be given for continued growth of the infrarenal neck after endovascular AAA repair. It is either a continuation of the aneurysmal disease process or an effect of the outward force generated by the endovascular stent onto the infrarenal aortic wall. Although it is most probably a combination of these two factors, it is interesting to discuss these issues separately, as the proximal attachment mechanisms vary Eur J Vasc Endovasc Surg Vol 19, Month 2000
200
J. J. Wever et al.
Fig. 3. Cross-sectional area at the suprarenal aortic neck in the 33 patients. Size in square millimetres is indicated on the vertical axis, and follow-up interval for each patient is indicated on the horizontal axis.
between the available stent-graft designs. If the outward force is the predominant cause of postoperative neck dilatation, the diameter will probably not stretch beyond the nominal (maximal) stent-size. But as the stent approaches its maximal size, the friction forces between stent and aortic wall may become dangerously low, with possible stent migration as a result. The preferred graft attachment design from this perspective would consist of a stent with low outward force to prevent accelerated dilatation and a fixation mechanism independent of friction forces between stent and neck (i.e. hooks). If progressive enlargement is merely a consequence of the underlying aneurysmal disease, the oversizing of the stent graft relative to the neck-size actually allows the stent to adapt to the neck dilatation. In this scenario, high outward force would not necessarily be detrimental to the neck. Although it may take a longer period of time, the end-result of continued neck dilatation in the presence of a stent with a limit to its diameter will ultimately be the same: potential graft migration if no other fixation mechanisms are present. In addition, dilatation beyond the nominal stent size may create a secondary attachment site leak, even without stent migration. Eur J Vasc Endovasc Surg Vol 19, Month 2000
Initial dilatation due to the procedure without subsequent dilatation cannot be considered an adequate explanation, as the increase of the proximal neck area was statistically significant for both the first and second 6 months’ follow-up interval. No significant increase of the suprarenal aorta was found in our study. Although this provides some support of the theory that progression of disease is not the only factor, it must be realised that the infrarenal aorta has a less dense fibre structure when compared to the suprarenal aorta.14 No correlation could be found between the presence or absence of endoleaks, pre- and postoperative neck-size, graft diameter and amount of graft oversize, probably due to small numbers. In conclusion, the infrarenal aortic neck demonstrates continued dilatation after endograft placement.
References 1 Sonesson B, Lanne T, Hansen F, Sandgren T. Infrarenal aortic diameter in the healthy person. Eur J Vasc Surg 1994; 8: 89–95. 2 Lipski DA, Ernst CB. Natural history of the residual infrarenal
Proximal Neck Dilatation after Endovascular AAA Repair
3 4 5 6 7
8
aorta after infrarenal abdominal aortic aneurysm repair. J Vasc Surg 1998; 27: 805–811. Illig KA, Green RM, Ouriel K et al. Fate of the proximal aortic cuff: implications for endovascular aneurysm repair. J Vasc Surg 1997; 26: 492–499. Curl GR, Faggioli GL, Stella A, D’Addato M, Ricotta JJ. Aneurysmal change at or above the proximal anastomosis after infrarenal aortic grafting. J Vasc Surg 1992; 16: 855–859. Sonesson B, Resch T, Lanne T, Ivancev K. The fate of the infrarenal aortic neck after open aneurysm surgery. J Vasc Surg 1998; 28: 889–894. Sonesson B, Malina M, Ivancev K et al. Dilatation of the infrarenal aneurysm neck after endovascular exclusion of abdominal aortic aneurysm. J Endovasc Surg 1998; 5: 195–200. Matsumura JS, Chaikof EL. Continued expansion of aortic necks after endovascular repair of abdominal aortic aneurysms. EVT Investigators. EndoVascular Technologies, Inc. J Vasc Surg 1998; 28: 422–430. May J, White G, Yu W et al. A prospective study of anatomicopathological changes in abdominal aortic aneurysms following endoluminal repair: is the aneurysmal process reversed? Eur J Vasc Endovasc Surg 1996; 12: 11–17.
201
9 Balm R, Eikelboom BC, van Leeuwen MS, Noordzij J. Spiral CT-angiography of the aorta. Eur J Vasc Surg 1994; 8: 544–551. 10 Broeders IA, Blankensteijn JD, Olree M, Mali W, Eikelboom BC. Preoperative sizing of grafts for transfemoral endovascular aneurysm management: a prospective comparative study of spiral CT angiography, arteriography, and conventional CT imaging. J Endovasc Surg 1997; 4: 252–261. 11 Balm R, van Leeuwen MS, Noordzij J et al. Spiral CT for aortic aneurysms. In: Greenhalgh RM, eds. Vascular Imaging for Surgeons. W. B. Saunders Co Ltd., 1995: 191–202. 12 Balm R, Kaatee R, Blankensteijn JD, Mali WP, Eikelboom BC. CT-angiography of abdominal aortic aneurysms after transfemoral endovascular aneurysm management. Eur J Vasc Endovasc Surg 1996; 12: 182–188. 13 Matsumura JS, Pearce WH, McCarthy WJ, Yao JS. Reduction in aortic aneurysm size: early results after endovascular graft placement. EVT Investigators. J Vasc Surg 1997; 25: 113–123. 14 Wolinsky H. Comparison of medial growth of human thoracic and abdominal aortas. Circ Res 1970; 27: 531–538. Accepted 13 August 1999
Eur J Vasc Endovasc Surg Vol 19, Month 2000