R.H.S. Gregson

Common iliac artery aneurysms in patients with abdominal aortic aneurysms

OBJECTIVES To determine the incidence of common iliac artery (CIA) aneurysms in patients with abdominal aortic aneurysms (AAA) and to evaluate the relationship between AAA and CIA diameter. METHODS Spiral CT angiography was used to measure the maximum diameters of the abdominal aorta and the common iliac arteries of 215 patients with AAA. RESULTS The median CIA diameter was 1.7 cm--significantly greater than the published mean of 1.25 (2 S.D. = 0.85-1.65) cm of an age-matched, non-vascular population. Thirty-four patients (16%) had unilateral and 26 patients (12%) bilateral CIA aneurysms > or = 2.4 cm diameter. Eight-six vessels (20%) were affected. Right CIA diameters were wider than left CIA diameters (p < 0.0001, Wilcoxon matched-pairs signed rank test). The correlation between AAA size and CIA diameter was weak. CONCLUSIONS The AAA population has abnormally dilated common iliac arteries. In this population, common iliac artery aneurysms should be defined as those greater than 2.4 cm diameter. 20% of CIAs in patients with AAA are aneurysmal according to this definition.

Early results of endovascular aortic aneurysm surgery with aortouniiliac graft, contralateral iliac occlusion, and femorofemoral bypass

PURPOSE The aim of this study was to evaluate the feasibility of endovascular aortic aneurysm repair with use of an aortouniiliac graft secured with self-expanding (Gianturco) stents. METHODS Thirty patients with a median age of 72 years (age range, 52 to 86 years) and aneurysm diameter of 6.0 cm (range, 4.0 to 9.0 cm) were treated with an aortouniiliac endovascular graft. Of these 30 procedures, 28 were carried out electively and two as emergencies for leaking aneurysm. Of the 30 patients, 21 (70%) were considered to be at high risk for open surgery. A modified Gianturco stent, Dacron graft, and Wallstent were used for these procedures. RESULTS Endovascular repair was successfully carried out in 25 of 30 (83.3%) patients. All these patients were mobile and had resumed a normal diet within 48 hours of the procedure. The overall 30-day mortality rate was two in 30 (6.6%), but it was one in 28 (3.5%) for the elective cases; all deaths occurred in the group at high risk for surgery. Other complications encountered within 30 days of procedure included myocardial infarction in one patient, pneumonia in two patients, homonymous quadrantanopia in one patient, and colonic ischemia in one patient, giving an overall morbidity rate of four in 30 (13.3%). At a median follow-up of 4 months (range, 1 to 13 months), 27 of 30 (90%) patients remain alive and well. CONCLUSION Endovascular aortouniiliac repair of abdominal aortic aneurysm with Gianturco stent is feasible in both elective and emergency situations. It appears to be minimally traumatic, and the majority of patients deemed to be at high risk for open surgery can safely undergo endovascular repair. However, data on more patients with longer follow-up is required to determine its role in the management of abdominal aortic aneurysm.

Anatomical suitability of ruptured abdominal aortic aneurysms for endovascular repair.

Purpose: To assess the anatomical suitability of ruptured abdominal aortic aneurysms (AAA) for emergency endovascular repair. Methods: All cases (46 patients [35 men; mean age 74 years, range 54–85]) in which computed tomographic angiography (CTA) confirmed AAA rupture over a 5-year period at our university hospital were reviewed for anatomical suitability for endovascular repair. Measurements were made by a radiologist experienced in anatomical assessment of CT criteria for elective endovascular aneurysm repair (EVAR). Results: The mean aneurysm neck length was 18 mm (range 0–59); 17 were conical, 13 straight, 4 barrel, and 6 reverse conical. Six cases had no proximal neck. Overall, 37 (80%) patients were unsuitable for EVAR according to our criteria. Nearly half the patients (22, 48%) had ≥2 adverse features. Unsuitable neck morphology (35, 76%) was the primary reason for exclusion, but CIA aneurysm (10, 22%) and EIA tortuosity (7, 15%) were secondary adverse features. Conclusions: With current stent-graft design, the majority of ruptured abdominal aortic aneurysms are anatomically unsuitable for endovascular repair.

Influence of Abdominal Aortic Aneurysm Size on the Feasibility of Endovascular Repair

PURPOSE To assess the effect of abdominal aortic aneurysm (AAA) size on overall aneurysm morphology with special attention to possible relationships among various anatomic variables that determine the feasibility of endovascular repair. METHODS One hundred sixty-eight patients were assessed with spiral computed tomographic angiography to measure the length and diameter of the AAA, the proximal neck, and the common iliac arteries. Anatomic variables were correlated with aneurysm size using Spearmans rank order correlation coefficients (rS); comparisons among small, intermediate, and large aneurysms were made using the Chi-square test. RESULTS Correlations between aneurysm size and the anatomic variables above were weak. The strongest association was between aneurysm size and aortic length (rS = 0.41, p < 0.001). Subgroup analysis showed no difference in proximal neck length, neck diameter, or overall suitability for endovascular repair between aneurysms greater or smaller than 5.5-cm diameter. However, significantly more short (< 1.5 cm), wide (> 3 cm), and hence, unsuitable proximal necks were found in patients with aneurysms > 7 cm in diameter (chi 2 = 7.8, p < 0.01). CONCLUSIONS Shortening and widening of the proximal neck seems to increase with aneurysm size but only after the aneurysm expands beyond 7 cm in diameter. Aneurysms with diameters in the 4.5- to 5.5-cm range are no more suitable for endovascular repair than those between 5.5 and 7 cm. The lack of any significant correlation between anatomic variables emphasizes the need for accurate preoperative assessment of the anatomy of each individual patient before endovascular repair.

A study on the patency of the inferior mesenteric and lumbar arteries in the incidence of endoleak following endovascular repair of infra-renal aortic enerysms

OBJECTIVE An endoleak is defined as the presence of contrast medium within the aneurysm sac on post-operative contrast-enhanced computed tomography scans (CT) in patients following endovascular repair (EVR) of abdominal aortic aneurysms (AAA). The aim of this study was to correlate the incidence of endoleaks with the presence of patent lumbar (LA) and inferior mesenteric arteries (IMA) as seen on pre-operative angiography. DESIGN, MATERIALS AND METHODS Forty-seven patients were assessed pre-operatively by both CT and angiography by a blinded radiologist prior to EVR of AAA. The number and size of patent vessels was recorded and correlated with the incidence of LA or IMA endoleaks on follow-up CT. Patent lumbar vessels were scored: 1 = small, 2 = medium, 3 = large. RESULTS Five patients were noted to have patent IMA on pre-operative angiography but none developed an endoleak. In this series, five patients had an endoleak due to a patent LA. The median score for patients with no endoleak was 1 (0-9) and for those with a lumbar endoleak 2 (0-5) (P = 0.26, Mann-Whitney U-test). The number of patent lumbar arteries was not predictive of a subsequent endoleak. Two out of nine (22 %) patients with large patent LA subsequently developed an endoleak. If a policy of pre-operative embolization on the basis of large patent LA had been adopted, seven patients would have had an unnecessary invasive procedure. CONCLUSION Pre-operative angiography to look for patent LA and IMAs is not required in patients undergoing EVR or AAA.

A prospective study to assess changes in proximal aortic neck dimensions after endovascular repair of abdominal aortic aneurysms

OBJECTIVE The purpose of this study was to detect any change in the proximal neck diameter after endovascular repair of abdominal aortic aneurysm. METHODS The study was performed in a teaching hospital with an endovascular program on 112 patients who had undergone endovascular repair of abdominal aortic aneurysm. The interventions were pre-endovascular and postendovascular repair of abdominal aortic aneurysms with contrast-enhanced, spiral computerized tomography, and the main outcome measures were change in aortic proximal neck diameter, change in maximum aortic diameter, presence of endoleaks, and change in length from lowest renal artery to aortic bifurcation. RESULTS The median anterior-posterior and transverse diameter decreased from 63.5 mm before surgery to 50.4 and 54.5 mm, respectively, after surgery in a period of 4 years. This trend in reduction in maximum diameter was not seen in the patients with endoleaks. There was no significant change in the proximal neck diameters when measured at 5-mm intervals after endovascular repair. There was also no significant change in the aortic length after endovascular repair. CONCLUSION We have not demonstrated any evidence for proximal neck dilatation after endovascular repair of abdominal aortic aneurysm.

Spiral CT angiography versus aortography in the assessment of aortoiliac length in patients undergoing endovascular abdominal aortic aneurysm repair.

Purpose: To compare measurements of aortoiliac length obtained with spiral computed tomographic angiography (CTA) and aortography in patients undergoing endovascular aneurysm repair. Methods: The distances from the lower-most renal artery to the aortic bifurcation and from the aortic bifurcation to the common iliac artery (CIA) bifurcation were measured using both CTA and aortography in 108 patients with abdominal aortic aneurysms. Results: The level of agreement between CTA and aortography was high, with 69% of aortic and 76% of iliac measurements within 1 cm and > 90% within 2 cm of each other. Mean differences were −0.35 ± 1.20 cm and 0.25 ± 1.10 cm, respectively, for aortic and iliac lengths. Aortography overestimated renal artery to aortic bifurcation length in comparison to CTA (p = 0.003), particularly in patients with large aneurysms (> 6.5 cm) and lumen diameters > 4.5 cm (p < 0.0001). Measurements of CIA length were shorter by aortography than CTA (p = 0.02). Conclusions: There is a high level of agreement between CTA and aortography in the measurement of aortoiliac length, but aortography overestimates renal artery to aortic bifurcation length in patients with large-diameter aneurysms and wide aneurysm lumens. CTA is sufficiently accurate in the majority of cases to be used as the sole basis for the construction of endovascular grafts.

The anatomy of abdominal aortic aneurysms: Implications for sizing of endovascular grafts

OBJECTIVE To determine the full range of aorto-iliac anatomy of patients with abdominal aortic aneurysms (AAAs) and thence the range of endovascular graft sizes required to deal with the majority of AAAs. DESIGN Analysis of preoperative spiral CT measurements. MATERIALS One hundred and sixty-eight patients with AAAs. METHODS Multiplanar reconstruction measurements were taken of proximal aortic neck diameter and length, lowermost renal artery to the aortic bifurcation distance and length and diameter of common iliac arteries. Based on these measurements a range of graft sizes that would fit the majority of AAAs was determined. RESULTS Ranges of anatomical variables were as follows: proximal aortic neck diameter 18-30 mm, renal artery to aortic bifurcation distance 93-210 mm, common iliac artery length 13-108 mm, common iliac artery diameter 6-67 mm. Over 750 graft sizes would be required to cover all anatomical combinations using a one-piece aorto-uni-iliac graft. CONCLUSION A wide variety of aorto-iliac anatomy exists in patients with AAAs. The large number of graft sizes required to deal with the majority of AAAs makes the production of one-piece endovascular grafts commercially impractical. A proposed two-piece modular graft would allow the majority of AAAs to be treated using only 16 graft sizes.

Endovascular AAA Repair: Classification of Aneurysm Sac Volumetric Change Using Spiral Computed Tomographic Angiography

PURPOSE To classify and analyze the volumetric changes seen on spiral computed tomographic angiography (CTA) following endovascular abdominal aortic aneurysm (AAA) repair. METHODS Fifty patients (46 men; mean age 71 years, range 51-83) with >1 year of imaging follow-up were retrospectively selected. The volume of the aneurysm sac was calculated on standard CT workstations to obtain plots of volume changes over time. For the purpose of this study, a 10% change in sac volume was considered significant. RESULTS Over a mean 32-month follow-up, 256 CTA scans were performed; initial mean sac volume was 259 mL and initial mean AAA diameter was 6.5 cm. Six distinct patterns of volume change were recognized: group Ia (28 patients, 56%): progressive reduction in aneurysm sac volume; group Ib (3 patients, 6%): transient initial increase then same as Ia; group II (4 patients, 8%): no significant change; group IIIa (5 patients, 10%): late increase in volume; group IIIb (8 patients, 16%): progressive increase in volume; and group IV (2 patients, 4%): late reduction in volume after secondary intervention. Group III changes were associated with endoleak types I and III (p<0.0001). CONCLUSIONS This classification system of spiral CTA volumetric changes features 6 patterns with recognized clinical significance and predictive value for endoleaks. Group I is the ideal outcome when the aneurysm sac shrinks and often completely disappears, while group III is associated with types I and type III endoleak and should prompt further investigation. Long-term volumetric analysis of all patients is advised.

Prospective randomised comparative study of pulse spray and conventional local thrombolysis.

OBJECTIVES To compare the time required to achieve lysis with the pulse spray technique and the conventional slow continuous infusion technique. DESIGN Prospective randomised open Study. METHODS Eighteen patients suitable for intra-arterial thrombolytic therapy with conventional and pulse spray technique were randomised 1:1 to receive either pulse spray thrombolysis with 0.33 mg/ml rt-PA injected as a bolus of 0.2 ml or conventional thrombolysis with 0.05 mg/ml rt-PA infused at a rate of 10 ml/h. RESULTS The age, duration of symptoms, length of occlusion and prethrombolysis ankle brachial pressure index were comparable in the two groups. The median duration of thrombolytic therapy in the pulse spray group was 195 min (range 90-1260) compared to 1390 min (range 300-2400) in the Conventional group. The difference between the two groups was significant, p < 0.002 (Mann-Whitney test). CONCLUSIONS Significantly shorter time is required to achieve local thrombolysis with pulse spray compared to the conventional infusion method.