Katja Vogt

Endograft Limb Occlusion in EVAR: Iliac Tortuosity Quantified by Three Different Indices on the Basis of Preoperative CTA

OBJECTIVE To assess the incidence and outcome of graft limb occlusions after endovascular aortic repair (EVAR) of abdominal aortic aneurysm (AAA) in a high volume single centre. To quantify iliac artery tortuosity in patients with AAA and correlate this with limb occlusion. DESIGN Data were collected consecutively and prospectively, and analyzed retrospectively. MATERIALS Patients treated with Zenith bifurcated stent grafts from January 2000 to December 2010 at a tertiary referral vascular unit were analyzed. Routine regular office follow-up with computed tomography angiography (CTA) and, subsequently, duplex ultrasound imaging was performed. Patients with limb occlusions were identified. For each index patient, two controls were obtained, one immediately preceding and one following the index patient in the consecutive cohort of EVAR patients. METHODS Demographics and CTA data on limb graft occlusions were recorded and compared with a defined control group. Three different indices were used to describe the tortuosity of the iliac vessels based on preoperative CTA: pelvic artery index of tortuosity (PAI), common iliac artery index of tortuosity (CAI), and a visual description of vessel tortuosity - the double iliac sign (DIS). Demographic data and indices were correlated for later occurring limb occlusion. RESULTS 504 patients underwent EVAR and 18 patients experienced graft limb occlusion during a median follow-up of 28 months (range 0-133). Primary graft patency was 97% at 1 year and 96% at 3 years. Logistic regression showed that iliac artery tortuosity (DIS) (p = .001) and body mass index (p = .007) had a significant impact on graft patency. CONCLUSION A tortuous vessel on the preoperative CTA is associated with an increased risk of limb occlusion after EVAR. Adjunctive stenting of iliac segments deemed at risk is suggested, which is achieved without compromise of the aneurysm repair.

Risk factors for incisional hernia repair after aortic reconstructive surgery in a nationwide study

OBJECTIVE Abdominal aortic aneurysm disease has been hypothesized as associated with the development of abdominal wall hernia. We evaluated the risk factors for incisional hernia repair after open elective aortic reconstructive surgery for aortoiliac occlusive disease and abdominal aortic aneurysm. METHODS A retrospective analysis of prospectively recorded data in nationwide databases was carried out, with merged data from the Danish Vascular Registry (January 2006-January 2012), the Danish Ventral Hernia Database (January 2007-January 2012), and the Danish National Patient Register (January 2007-January 2012) to obtain 100% follow-up for incisional hernia repair in patients undergoing open elective aortic reconstructive surgery. The predefined risk factors of age, sex, American Association of Anesthesiologists score, body mass index, smoking status, type of aortic surgery, and type of incision were tested in a multivariate Cox regression model for the risk of incisional hernia repair. RESULTS We identified 2597 patients, of whom 838 and 1759 underwent open elective surgery for an aortoiliac occlusive disease and abdominal aortic aneurysm, respectively. The median follow-up was 28.9 months (range, 0-71.6 months), and the cumulative risk of hernia repair after aortic reconstructive surgery was 10.4% after 6 years of follow-up. Body mass index >25.0 kg/m(2) (adjusted hazard ratio, 1.74; 95% confidence interval, 1.21-2.46) and abdominal aortic aneurysm repair (adjusted hazard ratio, 1.58; 95% confidence interval, 1.06-2.35) were significantly associated with incisional hernia repair. CONCLUSIONS High body mass index and abdominal aortic aneurysm repair were independent risk factors for a subsequent incisional hernia surgery in patients undergoing aortic reconstructive surgery.

Outcomes After Elective Aortic Aneurysm Repair: A Nationwide Danish Cohort Study 2007-2010

OBJECTIVE To assess outcomes after treatment for asymptomatic abdominal aortic aneurysm (AAA) in Denmark in a period when both open surgery (OR) and endoluminal repair (EVAR) have been routine procedures. METHODS We performed a retrospective nationwide cohort study of patients treated for asymptomatic AAA between 2007 and 2010. Data on demographics, procedural data, perioperative complications, length of stay (LOS), 30-day reinterventions and readmissions, late aneurysm and procedure-related complications and mortality were obtained from the Danish Vascular Registry and the Danish National Patient Register. RESULTS 525 EVAR and 1176 OR for asymptomatic AAA were identified. LOS was shorter after EVAR than OR (4 vs. 7 days, p < .001). During primary hospitalization procedure-related complications (12% vs. 6%) and general complications (21% vs. 8%) were more common after OR than EVAR (p < 0.001). The 30-day reintervention rate was higher for OR than EVAR (18% vs. 6%, p < 0.001), but there was no difference in readmissions within 30 days. During follow-up (mean 29 ± 15 months) aneurysm-related complications after EVAR were outweighed by procedure-related complications after OR. CONCLUSION Elective AAA repair in Denmark is overall comparable with international results and both perioperative and late outcomes after EVAR of elective AAA are better than the results after OR.

Influence of tissue preservation methods on arterial geometry and echogenicity.

Thoracic porcine aortas from 5 pigs were investigated with 7.5-MHz ultrasound in vitro at low and high transmural pressure before and after the following tissue preservation methods were applied: 1. Storage in frozen condition (-12 degrees C) for 24 h followed by thawing; 2. fixation in formalin at zero transmural pressure for 24 h; and 3. fixation with formalin for 24 h while applying 74 mmHg of transmural pressure from within the lumen and a tensile force to longitudinally stretch the artery. Fixation in formalin at zero transmural pressure resulted in swelling of the arterial wall (25 +/- 40%, p < 0.02, at low transmural measurement pressure) and in decreased echogenicity (-23 +/- 38%, p < 0.01) of the arterial vessel wall. No changes in this respect were found after storage in a frozen condition nor after fixation in formalin at high transmural pressure which, therefore, are more appropriate procedures for fixation of arteries prior to in vitro ultrasound examination if geometry is important.

Prediction of outcome after femoropopliteal balloon angioplasty by intravascular ultrasound

OBJECTIVE To evaluate intravascular ultrasound (IVUS) as a control procedure after femoropopliteal percutaneous transluminal angioplasty (PTA), and compare it with arteriography. DESIGN Descriptive study. MATERIAL Arteriographic and intravascular ultrasound data obtained from 18 patients (20 limbs) undergoing PTA of the superficial femoral or popliteal artery. The degree of stenosis, the diameter and area of the lumen and the morphological changes in the plaque were related to the short-term patency of the intervention, as evaluated by duplex scan and ankle branchial index. RESULTS Fifteen arteries remained patent. Two occlusions and two stenoses developed during the first 3 months after the intervention and one occlusion occurred after 1 year. The following IVUS parameters were related to a favourable patency: presence of calcification; dissection or plaque rupture and residual stenosis of less than 70%. The arteriographically determined diameter reduction did not show predictive value. CONCLUSION This study shows that in contrast to arteriography, IVUS revealed parameters predictive for patency following PTA.

Near-infrared spectroscopy during peripheral vascular surgery

Near-infrared spectroscopy was performed perioperatively on the dorsum of the foot in 14 patients who underwent infrainguinal bypass surgery using a prosthesis or the greater saphenous vein. Dual-wavelength continuous light spectroscopy was used to assess changes in tissue saturation before, during and after the operation. Following the use of peripheral vascular grafts an immediate postoperative increase in tissue saturation of median 28 (range -10 to +81) arbitrary units was noted (P < 0.01). Following distal clamping of the common femoral artery, maximal ischaemia corresponding to a median reduction in tissue saturation of 61 (range 6-94) units was reached after 26 (range 8-95) min (P < 0.01). The maximal tissue saturation following declamping was median 27 (range -16 to +100) units higher than the preoperative level (P < 0.01) and was reached after median 42 (range 8-125) min. The results indicate that near-infrared spectroscopy is appropriate for perioperative monitoring during vascular grafting.

Categorization of aortic aneurysm thrombus morphology by magnetic resonance imaging

BACKGROUND Magnetic resonance imaging (MRI) has been proposed for qualitative categorization of intraluminal thrombus morphology. We aimed to correlate the qualitative MRI categorization previously described to quantitative measurements of signal intensity and to compare morphological characteristics of intraluminal thrombus specimens to the appearance on magnetic resonance imaging. METHODS Thirty-four patients undergoing open surgery for abdominal aortic aneurysm had a preoperative MRI obtained with a 1.5 T magnet. Qualitative categorization was performed (blinded and in consensus) and correlated to intraluminal thrombus to muscle signal-intensity ratios. Morphology of intraluminal thrombus specimens collected during surgery were compared to the magnetic resonance imaging categories and specimen weight was correlated to thrombus volume measured on preoperative computer tomography angiography. RESULTS Blinded MRI categorization resulted in agreement in 22 out of 34 intraluminal thrombi (Kappa value 0.3, p=0.006). Medians (p=0.004) and distribution (p=0.002) of signal-intensity ratios varied significantly across the three MRI categories obtained by consensus. Heterogeneous and homogenous specimen appearance corresponded to similar appearances on MRI in 78% and 55% respectively, resulting in an overall Kappa=0.4 (p=0.04). Intraluminal thrombus volume and weight correlated well (rs 0.831, p<0.001) with a mean difference of 60 g (95% CI 38-80 g), without proportional bias. CONCLUSION Qualitative evaluation of intraluminal thrombus morphology based on MRI can be quantified by measuring signal-intensity ratios. Concurrently a fair agreement to blinded qualitative evaluation of thrombus specimens can be obtained. However, the evaluation is impaired by loss of a large proportion of thrombus during sampling.

Does Dopplersignal enhancement with Levovist improve the diagnostic confidence of duplex scanning of the iliac arteries?--(A pilot study with correlation to intravascular ultrasound)

OBJECTIVE To evaluate whether echo-enhancement with Levovist improves the diagnostic confidence of duplex scanning of the iliac arteries. METHODS Sixteen patients admitted for either PTA (n=7) or femoro-femoral cross-over bypass (n=9) were examined with duplex scanning before and after Levovist injection. The diagnostic confidence was noted before and after the echo-enhancement on a visual analog scale. The following day, intraoperatively, an IVUS examination of the iliac artery was performed. The agreement between duplex scanning before and after enhancement compared to IVUS was evaluated by kappa statistics, and sensitivity-specificity calculations. RESULTS The diagnostic confidence improved in 50% of the patients, remained unchanged in 44%, and deteriorated in one (6%) patient. The agreement with IVUS was moderate before enhancement (kappa=0.48) and good after the enhancement (kappa=0.63). Sensitivity rose from 64% (before) to 73% (after) Levovist while the specificity was unchanged (100%). These values are not as good as reported by others after fasting of the patients and comparing the results with arteriography. CONCLUSION Levovist improves the diagnostic confidence of duplex scanning, but marginally. In inconclusive duplex scannings echo-enhancement can supply decisive informations.

Quantification of iliac artery stenoses : A methodological comparative study between intravascular ultrasound, arteriography and duplex scanning

Two morphological methods for quantifying the degree of stenoses in the iliac arteries, intravascular ultrasound (IVUS) and arteriography, were compared with duplex scanning, a method of evaluating the haemodynamic importance of the stenosis. A total of 38 patients, 20 women and 18 men, median age 66 y, admitted for either PTA (n=18) or femoro-femoral crossover bypass surgery (n=20), were examined by IVUS, single plane arteriography and duplex scanning. The predictive value, sensitivity, specificity and kappa value of IVUS were higher than the corresponding values for arteriography. Logistic regression analysis found that IVUS had a predictive value (p=0.0003) for diagnosing significant stenosis as defined by duplex scanning, but arteriography did not (p=0.1). However, this difference in usefulness as predictors did not reach significance. The agreement between arteriography and IVUS was relatively good. The conclusion is that IVUS seems to be superior to single-plane arteriography in predicting hemodynamically significant stenoses as defined by duplex scanning.

The use of intravascular ultrasound for intraoperative assessment during semiclosed thrombeondarterectomy

To evaluate the application of intravascular ultrasound (IVUS) for intraoperative assessment of semiclosed thromboendarterectomy (TEA), IVUS images of the iliofemoral segment in 20 patients were obtained. The configuration and size of residual atherosclerotic material were evaluated. Stenoses in the artery proximal to the endarterectomized area were measured and, along with any remaining material, related to patency. Patency was evaluated at clinical controls after 3, 6, 12 and 24 months with duplex scanning and ankle-brachial index. In 10 cases (50%), material left behind from the endarterectomy was detected in the artery by IVUS. The material was removed in five cases. The part of the iliac artery proximal to the endarterectomized segment was visualized in 14 cases and showed minor stenoses in 10 cases. After follow-up at a median of 8 months (range 1-24), occlusion had occurred in one of 20 patients and restenosis (> 50%) had developed in two (10%). At this point, patency cannot be related to IVUS findings. We conclude that IVUS is a feasible method for intraoperative assessment of semiclosed TEA. The rate of early failures due to residual material might be reduced by this new application of IVUS.