The Relationship Between Operative Volume and Peri-operative Mortality After Non-elective Aortic Aneurysm Repair in Australia

OBJECTIVE

Hospital and surgeon operative caseload is thought to be associated with peri-operative mortality following the non-elective repair of aortic aneurysms; however, whether such an association exists within the Australian healthcare setting is unknown.

METHODS

The Australasian Vascular Audit was interrogated to identify patients undergoing non-elective (emergency [EMG] or semi-urgent [URG]) aortic aneurysm repair between 2010 and 2016, as well as their treating surgeon and hospital. Hierarchal logistic regression modelling was used to assess the impact of caseload on outcomes after both endovascular (EVAR) and open surgical repair (OSR).

RESULTS

Volume counts were determined from 14 262 patients (4 121 OSR and 10 141 EVAR). After exclusion of elective procedures and duplicates, 1 153 EVAR (570 EMG and 583 URG) and 1 245 OSR (946 EMG and 299 URG) non-elective cases remained for the analysis. Crude mortality was 24.0% following OSR (EMG 29.2%; URG 7.7%) and 7.5% following EVAR (EMG 12.6%; URG 2.4%). Univariable analysis demonstrated an association between OSR mortality and hospital volume (quintile [Q] 1: 25.3%, Q2: 27.8%, Q3: 23.9%, Q4: 27.0%, Q5: 16.2%; p = .030), but not surgeon (Q1: 25.2%, Q2: 27.4%, Q3: 26.0%, Q4: 21.4%, Q5: 19.5%, p = .32). Multivariable analysis confirmed this association (odds ratio (OR) [95% CI]; Q1 vs 5: 1.91 [1.13-3.21], Q2 vs. 5: 2.01[1.24-3.25], Q3 vs. 5: 1.41 [0.86-2.29], Q4 vs. 5: 1.92 [1.17-3.15]; p = .020). The difference was most pronounced in the EMG OSR group [Q1 - 3 vs. 4-5] (OR 1.63 [1.07-2.48]; p = .020). Mortality after EVAR was not associated with either hospital (Q1: 6.3%, Q2: 10%, Q3: 6.8%, Q4: 4.5%, Q5: 10%; p = .14) or surgeon volume (Q1: 9.3%, Q2: 5.7%, Q3: 8.1%, Q4: 7.0%, Q5: 7.3%; p = .67).

CONCLUSION

There is an inverse correlation between hospital volume and peri-operative mortality following EMG open repair of aortic aneurysm. These data support restructuring Australian pathways of care to direct suspected ruptured aneurysm to institutions that reach a minimum volume threshold.

Early Experience with the Sydney and EVT Prostheses for Endoluminal Treatment of Abdominal Aortic Aneurysms

Purpose:

The aim of this study was to report early experiences with the Sydney and Endovascular Technologies (EVT) prostheses for the treatment of abdominal aortic aneurysms (AAA) deemed suitable for endoluminal tube graft repair.

Methods:

Consecutive endoluminal tube graft repairs were analyzed over the first 12 months in which the Sydney and EVT prostheses were used. Patients eligible for the EVT prosthesis had type I AAAs: a proximal neck length ≥ 2 cm, a distal cuff length ≥ 1.5 cm, and nontortuous iliac arteries ≥ 8 mm. Selection criteria for the Sydney device were more liberal and included AAAs that had distal cuffs < 1.5 cm. During the study period, 28 of 91 patients evaluated for AAA repair were thus selected for endoluminal grafting: 18 patients received the Sydney endograft and 10 the EVT device. Medical comorbidities were present in slightly less than one third of patients in both groups. Contrast-enhanced computerized tomography (CT) was performed preoperatively, within 10 days of operation, and at 6 and 12 months postprocedure.

Results:

All endografts were successfully deployed in both groups. Postprocedural CT scans revealed incomplete aneurysm exclusion in four patients with the Sydney endograft. Subsequent deployment of a second endograft sealed these “leaks” in two cases; the other two were converted to open repair (89% clinical success). No leaks were seen with the EVT device. Local/vascular complications occurred in 33% of the Sydney group compared with 20% for the EVT device (p = 0.001); systemic sequelae were more common in the EVT group (30% versus 17% in the Sydney cohort, p = 0.002). There were no deaths within 30 days; three late deaths were not procedure related.

Conclusion:

AAAs that are suitable for endoluminal tube graft repair may be treated with a high rate of initial success with either the Sydney or EVT prostheses. More liberal selection criteria may increase the likelihood of local/vascular complications.

Proximal Stent Deployment without Contrast during Endovascular Aneurysm Repair: An Improved Technique

Purpose:

To describe a technique to enhance stent visibility on the fluoroscopic monitor during aortic endograft deployment.

Technique:

To assist in accurate positioning and deployment of the proximal stent in a Parodi-type aortic endograft, the stent is affixed to the balloon so that the radiopaque marker sits at the stent's distal end. When the device is in position and the sheath is retracted, the stent and the radiopaque balloon markers are clearly seen on the fluoroscopic image. Using normal saline only to inflate the balloon allows the stent to remain visible throughout deployment.

Conclusions:

The use of saline rather than contrast medium for balloon inflation provides continuous visualization of the stent during expansion, thus facilitating accurate deployment and early recognition of balloon migration within the stent.

Endovascular Stent-Anchored Aortic Grafts: A Comparison between Self-Expanding and Balloon-Expandable Stents in Minipigs

Purpose:

To study endovascular graft attachment with self-expanding Gianturco Z-stents and balloon-expanded Palmaz stents and the effect of these devices on the renal ostia.

Methods:

Ten stent-grafts were constructed, 5 with Gianturco Z-stents and 5 with Palmaz stents. The endografts were implanted under fluoroscopic guidance into the abdominal aorta of 10 pigs so that the uncovered portion of the proximal stent extended over the renal artery orifices. Distal aortic blood pressure and flow were measured before and after graft placement and 1 hour postprocedure. The aorta was then exposed surgically, and the central portion of the stent-graft was inspected through an aortotomy to assess perigraft leakage.

Results:

Stent-graft implantation was accurate and hemostatic in all cases, despite longitudinal folding of the graft due to oversizing. However, transverse folds produced pressure gradients (> 15 mmHg) between the ends of the graft in two cases. In another case, a pressure gradient resulted from partial thrombosis of the graft. In two cases, renal artery occlusion and thrombosis occurred due to coverage by the graft material. In two other animals, one of the renal arteries was entirely uncovered by a stent. The remaining 16 renal arteries were covered by the proximal stent but not the graft, as intended. One (6.25%) of these arteries thrombosed, but the remainder were grossly patent when the animals were sacrificed at 1 hour.

Conclusions:

Both Palmaz and Gianturco Z-stents produced hemostatic endovascular graft attachment, even in the presence of moderate graft oversizing. The risk of acute renal artery occlusion from juxtarenal stenting does not appear to be prohibitive, but longer term observations are needed.

Two-Center German Experience with Aortic Endografting

Purpose:

To report the results of a two-center study of endovascular abdominal aortic aneurysm (AAA) exclusion using a polyester-covered nitinol stent-graft.

Methods:

Candidates were evaluated with arteriography and computed tomography. Criteria for endovascular therapy were a proximal aortic neck > 10 mm in length and < 25 mm in diameter, no bilateral internal iliac artery involvement in the aneurysm, no markedly tortuous common iliac arteries (CIAs) or CIAs < 7 mm in diameter, and no superior mesenteric artery occlusive disease. Patients were treated with the Mialhe Stentor and Vanguard stent-grafts in either tube or bifurcated versions.

Results:

Between August 1994 and November 1996, 149 patients (mean age 67 years, range 49 to 90) were admitted to the study. Overall primary technical success (aneurysm exclusion without endoleak) was 87% (130 patients): 78% (7 patients) for tube grafts and 88% (123 patients) for bifurcated endografts. The rate of local, remote, or systemic complications was 10.8%, with a 30-day mortality rate of 0.7%. During an average 13.5-month follow-up, there were no late deaths. Four of 20 endoleaks sealed spontaneously, 14 were treated with endoluminal techniques, and 2 remain untreated by patient request. Three graft limb thromboses occurred; one was treated surgically, one with lytic therapy, and one was untreated. Secondary patency was 96%.

Conclusions:

Endoluminal repair of infrarenal AAAs using straight or bifurcated grafts is a feasible alternative to conventional surgical repair. Longer follow-up and more experience with refined endograft models will elucidate the durability of this endovascular approach to treating AAAs.

A New Nonstented Balloon-Expandable Graft for Straight or Bifurcated Endoluminal Bypass

Purpose:

The aim of this study was to determine the feasibility of endoluminal grafting of aneurysms using a new design of nonstented endograft.

Methods:

Initial studies were undertaken in bench models and by implantation of endografts into animal vessels. Between May 1992 and June 1994, endoluminal repair of aneurysms was undertaken in 47 patients (44 male, 3 female). A new balloon-expandable endoluminal graft was developed and has now been studied in 25 of these 47 cases. This graft does not require adjunctive use of a vascular stent because of its unique construction, which incorporates metallic implants (graft attachment device or “GAD”) into the graft material. The design is applicable to endovascular grafting of occlusive arterial disease, as well as aneurysms. All patients were investigated by duplex scan, calibrated angiogram, and angio-CT scan and then allocated into groups that we defined according to the following criteria: group I, considered suitable for transfemoral implantation of a straight tube graft (n = 12); group II, unsuitable for transfemoral tube graft because of short neck of aneurysm, absent distal neck, or diseased iliac arteries (n = 10); and group III, peripheral aneurysms (n = 3). All patients were followed by clinical examination, duplex scan, and CT scan, with selective use of angiography.

Results:

Intraluminal deployment of the graft was achieved in all 25 patients; however, 3 patients from group II subsequently required conversion to open procedures because of the following complications: (1) partial graft thrombosis resulting from inadvertent omission of systemic anticoagulation during deployment (n = 1); and (2) unsuccessful deployment of the contralateral limb of a bifurcated graft in the iliac artery (n = 2). Successful endoluminal repair was achieved in 100% of patients in groups I and III, compared to 70% in group II.

Conclusions:

These preliminary results (in a series of high-risk patients) have demonstrated that endoluminal abdominal aortic aneurysm repair with this graft can be achieved reliably and with low morbidity in patients who fulfill the selection criteria (group I) and in peripheral aneurysms (group III), but the results were less satisfactory in aneurysms that do not have a good proximal or distal neck or in patients with diseased iliac arteries (group II). Further modification of the bifurcated version of this graft design, together with improvements in access techniques and graft materials, is required for successful endoluminal grafting in a wider range of patients.

Endoluminal Grafting for Percutaneous Aneurysm Exclusion in an Aortocoronary Saphenous Vein Graft: The First Clinical Experience

Purpose:

Aneurysms develop only rarely in aortocoronary saphenous vein grafts (SVGs), and the usual treatment is surgical replacement of the diseased segment. However, in patients at appreciable risk for redo surgery, alternative therapies are desirable. We report the first compassionate use of a percutaneously delivered endoluminal graft (ELG) for internal exclusion of an SVG aneurysm.

Methods:

A 47-year-old male with two coronary bypass procedures and SVG angioplasty presented with an 8-mm diameter aneurysm lying between 80% and 70% stenotic lesions in an SVG to the obtuse marginal branch. The risks of a third bypass operation were considerable, so the decision was made to attempt internal exclusion of the SVG aneurysm.

Results:

An ELG composed of 2.0-mm diameter unexpanded PTFE graft material with Palmaz stents for fixation was delivered with a low-profile system, but a second ELG was necessary for complete exclusion of the aneurysmal sac. Both ELGs were dilated after initial deployment. The patient was discharged after 9 days without sequelae, and he remains asymptomatic with arteriographically documented ELG patency 5 months after treatment.

Conclusions:

In this patient with limited therapeutic options, percutaneous aneurysm exclusion in an SVG was effective in restoring a viable blood conduit. It remains to be seen if ELGs have a potential in aortocoronary SVGs.

Endoluminal Repair of Abdominal Aortic Aneurysms: Strengths and Weaknesses of Various Prostheses Observed in a 4.5-Year Experience

Purpose:

To summarize the results of endovascular abdominal aortic aneurysm (AAA) treatment using several endograft designs over a 4.5-year experience and offer comparisons on the various devices.

Methods:

From May 1992 to August 1996, 121 AAA patients meeting the criteria for an endoluminal repair were treated with 1 of 5 endograft designs in three configurations. The endografts were implanted in the operating room under fluoroscopic control. Follow-up included contrast-enhanced computed tomography within 10 days of operation, 6 months postoperatively, and annually thereafter.

Results:

Endografts were successfully deployed in 106 patients (88%). Fifteen cases were converted to open repair. Six procedure-related deaths occurred within 30 days owing to myocardial infarction (3), combined renal failure and septicemia (2), and multisystem failure (1). There were 36 local/vascular complications (30%) and 18 systemic/remote complications (15%). Of the 121 patients undergoing endoluminal AAA repair, 93 (77%) are currently alive and well with their AAAs excluded from the circulation.

Conclusions:

Trends in endoluminal AAA repair and prosthetic design point toward simpler devices and earlier treatment of smaller aneurysms once the long-term outcome of aortic endografting has been determined.

Endoleak as a Complication of Endoluminal Grafting of Abdominal Aortic Aneurysms: Classification, Incidence, Diagnosis, and Management

The inability to obtain or maintain a secure seal between a vessel wall and a transluminally implanted intra-aneurysmal graft is a complication unique to the evolving technique of endovascular aneurysm exclusion. Because the term “leak” has long been associated with aneurysm rupture, the term “endoleak” is proposed as a more definitive description of this phenomenon.

Embracing both persistent blood flow into the aneurysmal sac from within or around the graft (graft related) and from patent collateral arteries (nongraft related), endoleak can be classified as primary or secondary depending on the time of occurrence (within 30 days of implantation or following apparent initial seal, respectively).

Diagnostic techniques to detect endoleak include arteriography, intraprocedural pressure monitoring, contrast-enhanced computed tomography, abdominal X ray, and duplex scanning. Management strategies for endoleak range from observation with periodic imaging surveillance to correction by additional endoluminal or surgical procedures.

Standardization of the terminology describing this important sequela to endovascular aneurysm exclusion should facilitate uniform reporting of clinical trial data vital to the evaluation of this emerging technique.

Adenosine-Induced Transient Cardiac Asystole Enhances Precise Deployment of Stent-Grafts in the Thoracic or Abdominal Aorta

Purpose:

To present a cardiac asystole technique that assists in the accurate deployment of stent-grafts during endovascular repair of thoracic or abdominal aortic aneurysms.

Technique:

In the anesthetized patient, trial doses of intravenous adenosine are delivered until a ≥ 20-second period of asystole is recorded. The endograft procedure then proceeds until the device is ready for deployment. The predetermined dose of adenosine is administered, and the device is deployed during asystole. Adenosine-induced transient asystole has been utilized in 16 patients undergoing balloon-expandable endograft exclusion of 6 thoracic aortic and 10 abdominal aortic aneurysms. Asystole lasted for 20 to 30 seconds, during which time the devices were accurately deployed without interference from the aortic flow. There were no clinical sequelae of this technique in any patient.

Conclusions:

Pharmacologically induced transient asystole appears to be a safe maneuver to preclude endograft movement by systolic blood flow. The technique permits precise placement of balloon-expandable stent-grafts and is applicable to self-expanding devices as well. Interventionists may wish to incorporate adenosine-induced asystole into their aortic aneurysm exclusion procedures.

Angioscopic Evaluation of an Endoluminal Aortic Graft: The First Clinical Experience

Purpose:

Balloon aortoscopy has been described for viewing aortic endoluminal anatomy and guiding aortic stent placement in animals. We report the first clinical use of this technique to visually inspect the proximal portion of a 1-year-old endovascular aortic graft, its proximal fixation stent, and its relationship to the renal arteries.

Methods:

The aortoscope is a modified fiber-optic endoscope that is fitted over the lens with a transparent, saline-filled balloon for blood displacement. Its performance was evaluated in a 62-year-old woman who had a Parodi-type Dacron/modified Palmaz stent endoluminal graft implanted to exclude an infrarenal aortic aneurysm in 1994. One year later, during an angioplasty procedure for symptomatic left subclavian and left common iliac artery stenoses, the 1-year-old endoluminal graft was inspected with the balloon-tipped angioscopic assembly.

Results:

Introduced via the left brachial artery, the aortoscope provided a panoramic view of the endoluminal surface through the solution-filled balloon. The endoluminal aortic graft was clearly identified, as were both renal artery orifices proximal to the graft. The surface of the proximal stent was smooth and without exposed metal. No complications occurred with the angioscopy technique.

Conclusions:

Aortic angioscopy can be used to evaluate endoluminal aortic grafts and endoluminal anatomy. It provides clear, magnified views that may be useful for guiding precise placement and assessing the function and healing of endoluminal devices in the aorta.

Torsion and Kinking of Unsupported Aortic Endografts: Treatment by Endovascular Intervention

Purpose:

To describe the management strategies used to deal with twisted aortic endografts.

Methods and Results:

Two patients with successfully excluded aortic aneurysms developed symptoms referable to previously undetected twists in their endografts (one EndoVascular Technologies [EVT] and one customized aortomonoiliac device). The limb graft occlusion in the EVT graft was treated surgically with a femorofemoral bypass, but the aortomonoiliac endograft was salvaged with percutaneous implantation of a Wallstent. During another aortomonoiliac procedure, suboptimal flow through the endograft was traced to contortion of the endograft as it passed over an angulated proximal aneurysm neck. An X-large Palmaz stent was deployed to support the graft at this point.

Conclusions:

Unsupported aortic endografts may develop twists and kinks during deployment that can lead to low outflow and graft occlusion. Endovascular techniques are available to repair these defects postoperatively, although more precise intraoperative assessment tools may identify these problems so that they can be corrected at the initial intervention.

The Italian Trial of Endovascular AAA Exclusion Using the Parodi Endograft

Purpose:

To report the outcome of the prospective 11-center Italian Parodi Trial using straight and tapered endografts for the endovascular exclusion of abdominal aortic aneurysms (AAA).

Methods:

From April 1994 to July 1995, 27 patients were evaluated and selected for endovascular AAA exclusion. The Parodi devices were delivered through femoral arteriotomies using 18 to 22F introducers and deployed by balloon expansion of the terminal stents.

Results:

Of 27 cases attempted, 24 endografts (15 tube, 9 aortomonoiliac) were implanted (1 deployment and 2 access failures [11.1%] were converted). Three endoleaks (12.5%) were treated intraoperatively with covered stents, two successfully, and the third sealed within 30 days. Three (12.5%) of the 24 treated patients died in-hospital of device- (n = 2) and procedure-related (n = 1) causes; the remaining 21 patients were discharged within 8 days. Of the 8 aortomonoiliac grafts in follow-up, only 1 (12.5%) failed in the mean 23-month (range 18 to 30) follow-up; however, 4 (31%) of 13 tube graft patients were converted to surgery within 18 months. Of the 16 (66.7%) surviving endografts at 2 years, 6 (38%) showed no change in the AAA diameter, while 10 (62%) had shrunk.

Conclusions:

The tube graft was applicable in only about 5% of cases, and accurate endograft sizing and distal fixation were problematic. The aortomonoiliac design was not appealing to surgeons but fared better in the long term. Given the advent of newer endograft models, the Italian Parodi Trial has been terminated.

An Experimental Model for the Acute and Chronic Evaluation of Intra-Aneurysmal Pressure

Purpose:

To develop an animal model for the acute and chronic monitoring of pressure within abdominal aortic aneurysms (AAAs) to be treated with endovascular grafts.

Methods:

A strain-gauge pressure transducer was placed within an AAA created from a prosthetic vascular graft. Prosthetic aneurysms were implanted into 17 canine infrarenal aortas. The intra-aneurysmal pressure was monitored and correlated with noninvasive forelimb sphygmomanometry for 2 weeks. After this time, an intravascular manometer catheter was passed into the aneurysm. Simultaneous pressure measurements were obtained using the implanted strain-gauge pressure transducer, the manometer catheter, and the forelimb sphygmomanometer. Angiography was performed to assess intraluminal morphology, aneurysm anastomoses, and adjoining aortic vessels. In addition, two control animals underwent intra-aneurysmal pressure monitoring after standard surgical aneurysm repair.

Results:

There was excellent correlation (r = 0.97) between the pressure measurements obtained with the implanted strain-gauge pressure transducer and the intravascular manometer. Close correlation was also observed between the implanted strain-gauge transducer and the forelimb sphygmomanometer (r = 0.88) during postprocedural monitoring. Intra-aneurysmal pressure was lowered dramatically by surgical exclusion (aneurysm: 15/5 ± 7/4 mmHg; systemic: 124/66 ± 34/17 mmHg; p < 0.001). The prosthetic aneurysms were successfully imaged with angiography.

Conclusions:

This animal model provides an accurate and reproducible means for measuring intra-aneurysmal pressure on an acute and chronic basis. It may be possible to use this model in the assessment of endovascular devices to determine their efficacy in reducing intra-aneurysmal pressure. Evaluation of complications associated with their use, such as patent aneurysm side branches, perigraft channels, and perianastomotic reflux, may also be possible.

Shortening of Endografts during Deployment in Endovascular AAA Repair

Purpose:

To evaluate the incidence and extent of length changes during implantation of endovascular grafts in a prospective study of patients undergoing endovascular abdominal aortic aneurysm (AAA) repair.

Methods:

Data regarding the occurrence of intraoperative technical difficulties and device complications were recorded prospectively for the Vanguard or AneuRx self-expanding, bifurcated endovascular grafts in 64 patients (56 males; mean age 75 years). Graft length was measured in the sheath system before deployment and again immediately after deployment by fluoroscopic comparison to a graduated marking catheter.

Results:

Graft shortening ≥ 15 mm was documented in 22 (56%) of 39 Vanguard cases and 11 (44%) of 25 AneuRx endografts. Additional extension grafts were required to correct endoleak caused by inadequate graft length in 9 (14%) patients, but no conversion to open repair was necessary.

Conclusions:

There appears to be a high incidence of intraprocedural graft shortening with 2 current designs of self-expanding endoluminal grafts.

Endovascular management of iliac rupture during endovascular aneurysm repair

BACKGROUND

Inadequate iliac artery diameter, calcification, and tortuosity are associated with increased incidence of iliac injury during abdominal (EVAR) and thoracic endovascular aneurysm repair (TEVAR). Despite careful preoperative assessment and use of iliac conduits, inadvertent iliac rupture is a source of morbidity and mortality. This report details our single-center, 10-year experience with intraoperative iliac artery rupture and describes a successful endovascular salvage technique.

METHODS

All patients undergoing EVAR and TEVAR between August 1997 and June 2008 were reviewed. Computed tomography (CT) measurements of access vessels were obtained for all patients. The smallest diameter of the external or common iliac artery was used to determine suitability for access based on the instructions for use for each device. Patients who underwent repair of a procedure-related iliac artery rupture were identified. Outcomes among patients who did not have an access vessel rupture (nonruptured group) and those who did (ruptured group) were compared. Patency of the endovascular iliac repair is reported.

RESULTS

During the study period, 369 EVARs and 67 TEVARs were performed. Eleven iliac conduits were used, all during TEVAR (16%). There were 18 ruptured iliac arteries in 17 patients; 11 EVAR patients (2.98%) sustained iliac rupture vs six TEVAR patients (8.9%). One EVAR patient was converted to open repair. Seventeen ruptures in 16 patients were successfully treated with endovascular stent graft placement. Iliac rupture was more likely to occur during TEVAR (8.9%) than EVAR (2.98%; P = .0239, Fisher exact test). Significantly more women were in the ruptured group (76% vs 19%; P < .0001, Fisher exact test). Patients in the ruptured group had longer lengths of stay (7.6 vs 5.1 days; P = .0895, t test), no 30-day mortality, but a procedure-related mortality of 11.8%. In the nonrupture group, 30-day mortality was 6.6% (4 of 61) and 2.8% (10 of 358) for TEVAR and EVAR, respectively, and procedure-related mortality was 9.8% (6 of 61) and 3.1% (11 of 358). For endovascular repair of iliac rupture, primary and primary-assisted patency was 88.2% and 94.1%, respectively, with median follow-up of 40 months (range 10-115 months).

CONCLUSION

Iliac rupture during EVAR or TEVAR can be successfully managed with endovascular stent grafting. Higher mortality and length of stay associated with iliac artery rupture confirm that there is no substitute for prevention. Access vessels of all patients undergoing EVAR should be examined closely for suitability. The threshold for using an iliac conduit, especially in women undergoing TEVAR, should be low.

Three-dimensional intravascular ultrasound assessment of abdominal aortic aneurysm necks

PURPOSE

To document the accuracy of an automated analysis system for measuring lumen diameter and neck lengths of abdominal aortic aneurysms (AAAs) from intravascular ultrasound (IVUS) images and to describe additional features associated with 3-dimensional (3D) IVUS imaging.

METHODS

Twenty-two aortic aneurysms were studied with IVUS. Lumen diameters obtained using the automated analysis system were compared with manual measurements from axial IVUS scans, as were neck lengths obtained using automated analysis versus those measured with the aid of a displacement sensing device. Automated analyses were repeated by a second observer. Agreement was expressed as the coefficient of variation (CV).

RESULTS

Twenty proximal aortic, 6 distal aortic, and 3 iliac necks were available for analysis. Comparison between automated analysis and manual measurements for lumen diameter revealed a difference of 0.45 +/- 0.42 mm (mean +/- SD, Pearson's r = 0.99, p < 0.001, CV = 2.1%) and a difference of 0.05 +/- 0.12 cm (r = 0.99, p = 0.04, CV = 4.1%) for neck length. Interobserver difference for lumen diameter was 0.13 +/- 0.66 mm (r = 0.99, p < 0.001, CV = 3.4%) and 0.05 +/- 0.11 cm for length measurements (r = 0.99, p = 0.02, CV = 3.5%). The 3D IVUS imaging facilitated the identification of neck configuration.

CONCLUSIONS

Automated analysis of IVUS images allows accurate measurement of the lumen diameter of proximal and distal AAA necks and gives length measurements comparable to those of manual analysis. Longitudinal display of IVUS images aids in the elucidation of neck anatomy.