Hans O. Myhre

The Need for Clinical Trials of Endovascular Abdominal Aortic Aneurysm Stent-Graft Repair: The EUROSTAR Project

EUROSTAR(EUROpean collaborators on Stent-graft Techniques for abdominal aortic Aneurysm Repair) was established for the purpose of combining and studying data on endovascular abdominal aortic aneurysm (AAA) repair. EUROSTAR is independent of any commercial interest and has as its ultimate goal an independent, scientifically reliable assessment of endovascular AAA grafting. A standardized case record form is used for data collection and transmission, and the database is maintained in a central registry office. A comprehensive set of clinical, imaging, technical, and laboratory data obtained at initial admission and follow-up are recorded; these data are analyzed periodically and reports generated on the collated experience. As a first priority, an observational study without controls was initiated in July 1996 to address the issues of procedural safety, device durability, and long-term effect upon the aneurysms. Several ancillary studies have been initiated, including a “Retrieval and Analysis Study” for the evaluation of explanted devices. While a randomized study does not seem feasible at present, this may be organized at the appropriate time when the devices and techniques become more standardized.

Inflammatory aortic aneurysm is associated with increased incidence of autoimmune disease

OBJECTIVE It has been suggested that certain genetic risk factors indicative of an autoimmune mechanism can be identified in patients with inflammatory aortic aneurysm (IAA). We therefore investigated whether there was a higher incidence of autoimmune diseases in patients with IAA. Further, we explored risk factors, need for in-hospital resources, and early results of treatment, in a case-control study in a university hospital setting. Material and methods From 1983 to 1994, 520 patients were operated because of abdominal aortic aneurysm (AAA). Thirty-one patients had IAA. Control subjects were matched for aneurysm rupture, emergency or elective hospital admission, and date of operation. Two noninflammatory AAA were included for every IAA. RESULTS Of the 31 patients with IAA, 6 patients (19%) had autoimmune disease, compared with none of the control subjects (P =.0017). Two patients had rheumatoid arthritis, 2 patients had systemic lupus erythematosus, 1 had giant cell arteritis, and 1 patient had an undifferentiated seronegative polyarthritis diagnosed as rheumatoid arthritis. Nineteen patients (61%) with IAA had involvement of the duodenum, and 8 patients (26%) had hydronephrosis with ureteral involvement. Operating time was longer in the IAA group, which also had a higher need for blood transfusion. Hospital stay, intensive care unit stay, and 30-day mortality were similar in the two groups. CONCLUSION Except for longer operating time and more need for blood transfusions in the IAA group, use of hospital resources was similar after operations to treat IAA or noninflammatory AAA. The study findings indicate an association between IAA and autoimmune disease. This is in accordance with other reports that showed a genetic risk determinant mapped to the human leukocyte antigen (HLA) molecule in these patients. Further research is necessary to explore whether IAA might be a separate entity with a role of antigen binding in the origin of the disease.

A new method for analysis of motion of carotid plaques from RF ultrasound images

Motion of carotid artery plaques during the cardiac cycle may contribute to plaque disruption and embolism. We have developed a computerized method that objectively analyzes such motion from a sequence of ultrasound (US) radiofrequency (RF) images. A displacement vector map is obtained by 2-D correlation of local areas in consecutive images. From this map, motion dynamics can be quantified and presented as function of time, spatial (image) coordinates or as single numbers. Correct functionality has been verified on laboratory data. Applied to patient data, the method gives temporal results that correlate well with ECG data and the calculated peak systolic velocities of typically 10 mm/s agree well with values reported in the literature. The spatial analysis demonstrates that different plaque regions may exhibit different motion patterns that may cause internal stress, leading to fissures and plaque disruption. Thus, the motion analysis method may provide new and important information about the plaque characteristics and the prospective risk of cerebrovascular events.

Initial observations of endovascular aneurysm repair using Dyna-CT.

Purpose: To examine the feasibility of a new technology that provides images resembling computed tomographic (CT) slices on the operating table during elective endovascular abdominal aortic aneurysm (AAA) repair (EVAR). Technique: Commercially available Dyna-CT equipment was used in conjunction with Voxar 3D software for image reconstruction. During the preliminary evaluation of 9 patients (7 men; median age 73 years, range 67–84) with non-ruptured AAA undergoing elective EVAR with the Zenith Trifab stent-graft under regional anesthesia, the equipment functioned sufficiently well to produce the planned image dataset in 8 of 9 patients. Rotation failed in 1 overweight individual due to a short distance between the patients abdomen and the C-arm. In 7 of 8 patients, the radiologist was able to measure the diameter of the aneurysm, and it was possible to visualize the entire length of the treated aorta and the iliac arteries in all cases. The proximal aortic neck, including the stent-graft, was visualized in 7 cases. No endoleak or other complications was detected, which was confirmed on the pre-discharge CT scans. The time interval from the rotation of the C-arm until the appearance on the monitor of the first automatically generated 3D images was 7 minutes, which has subsequently been reduced to ∼2 minutes. Conclusion: Our preliminary experience with Dyna-CT is promising, but further research is necessary to define the place of this imaging modality in EVAR.

Regional Anesthesia for Endovascular Treatment of Abdominal Aortic Aneurysms

Purpose: To investigate the feasibility of regional anesthesia for endovascular repair of abdominal aortic aneurysms (AAAs). Methods: Since February 1995, 21 patients (17 men and 4 women; median age 67 years, range 49 to 80) have been treated with endovascular technique for true infrarenal AAA using Mialhe Stentor bifurcated grafts. A single dose of spinal anesthesia combined with epidural anesthesia was used in all procedures. Electrocardiography and arterial blood pressure were monitored. Results: No cases of emboli, hematoma, or graft migration were seen, and there were no reoperations or conversions to open operation. Arterial blood pressure was stable at a satisfactory level from induction of anesthesia throughout the procedure, and there was no period of clinically significant hypotension during any implantation. One patient died on the second postoperative day from cardiac and renal insufficiency. Three endoleaks were observed during the procedure; one healed spontaneously within 5 weeks, and the other two were repaired by endovascular techniques after 1 and 4 months, respectively. During follow-up, one patient died at 6 months from pancreatic carcinoma. Conclusions: The application of regional anesthesia is feasible for endovascular treatment of AAA. The arterial blood pressure remained stable throughout the procedure, and all patients, with two exceptions, were mobilized on the first day and placed on a regular diet. Based on these early results, it appears that regional anesthesia is feasible, effective, and safe for endovascular AAA repair.

The Use of MRI in the Investigation of Leg Oedema

Magnetic resonance imaging (MRI) was used in the diagnosis of various conditions giving rise to leg oedema, with special attention to the oedema after femoro-distal vascular reconstruction for obliterative atherosclerosis (n = 14). Patients with deep venous thrombosis (n = 6), chronic lymphoedema (n = 6) and closed muscular compartment syndrome (n = 2) were also investigated. Leg volume increase was measured according to the formula of a truncated cone. Interstitial fluid hydrostatic pressure (Pif) was recorded with the wick-in-needle technique. Spin echo series with 10 mm transverse slices were obtained with MRI. Following vascular reconstructions, leg volume increased 26% on the operated side. In the operated leg, no gradient in Pif was found between the posterior muscular compartment and the subcutaneous tissue. However, there was a significantly higher Pif in the subcutaneous tissue compared to the anterior muscular compartment (p less than 0.05). In the operated group, MRI revealed oedema around the entire circumference of the leg, mainly restricted to the subcutaneous tissue. In contrast, oedema of the leg muscles, particularly in the posterior compartments, was typical for patients having deep venous thrombosis. The group with chronic lymphoedema showed circumferential subcutaneous oedema alone or in combination with a fibrotic honeycomb pattern. Oedema of the affected muscular compartment was easily observed in patients who had a closed compartment syndrome. In conclusion, the use of MRI is promising in the investigation of conditions giving rise to leg oedema. It is likely that the formation of post-reconstructive oedema is taking place in the subcutaneous tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

DynaCT during EVAR – A Comparison with Multidetector CT

OBJECTIVES We have explored the usefulness of an on-table, cross-sectional radiological imaging (DynaCT) in endovascular aortic repair (EVAR). DynaCT images were compared to images from a regular multidetector (16 slice) CT. In the comparison, we tested the accordance of firstly 5 relevant clinical measurements and secondly the visibility of 9 anatomical areas in the two different types of images. This imaging was carried out in addition to the usual angiographic imaging. DESIGN, MATERIAL AND METHOD: 20 patients with infrarenal abdominal aortic aneurysm (AAA) were prospectively enrolled in the study. We compared Images from DynaCT with two different doses of contrast medium to MDCT-images in two different ways. Firstly relevant arterial diameters and lengths and secondly, 9 anatomical areas were evaluated regarding visibility which was scored on a 4-point scale. RESULTS There were no significant differences in the measured arterial diameters and lengths. MDCT had a significantly higher visibility score than both DynaCT investigations. However, with the highest contrast medium dose we found acceptable diagnostic quality in 78-94% of the cases for 8 of the 9 investigated anatomical areas. CONCLUSION Our findings indicate that on-table DynaCT are of sufficient quality to give relevant information of arterial measurements, needed in endovascular repair of infrarenal aortic aneurysms.

Early Results after Treatment of Open Abdomen after Aortic Surgery with Mesh Traction and Vacuum-Assisted Wound Closure

OBJECTIVES This study aimed to describe the use of vacuum-assisted wound closure (VAWC) and mesh traction to repair an open abdomen after aortic surgery. DESIGN Prospective clinical study. MATERIAL AND METHODS From October 2006 to April 2009, nine consecutive patients were treated; seven of the patients received laparostomy following abdominal compartment syndrome (ACS), while two wounds were left open initially. The indication for laparostomy was intra-abdominal pressure (IAP) > 20 mmHg or abdominal perfusion pressure (APP) < 60 mmHg and development of organ failure. V.A.C. therapy (KCI, San Antonio, TX, USA) was initiated with the laparostomy, and supplemented with a fascial mesh after 2 days. The wound was then closed stepwise with mesh traction and VAWC. RESULTS All wounds could be closed following a median interval of 10.5 (range: 6-19) days after laparostomy. A median of four (range: 2-7) dressing changes were performed. One patient died on the seventh postoperative day. Two other patients died 38 and 50 days after final closure, respectively. Left colonic necrosis was seen in two patients while incisional hernia was observed in two patients. Mean follow-up duration was 17 (range: 2-36) months. CONCLUSION VAWC with mesh traction was successful in terms of early delayed primary closure and is a useful tool in the treatment of open abdomen after aortic surgery.

Lymph drainage and the development of post-reconstructive leg oedema is not influenced by the type of inguinal incision. A prospective randomised study in patients undergoing femoropopliteal bypass surgery.

OBJECTIVES To see whether the type of groin incision influenced the degree of postoperative leg oedema and the occurrence of lymphatic damage. DESIGN Prospective randomised clinical study. SETTING University Department of Surgery. MATERIALS Twenty-four patients undergoing femoropopliteal bypass reconstruction with either a lateral groin incision (Group A, n = 12) or a direct incision over the femoral vessels (Group B, (n = 12). CHIEF OUTCOME MEASURES The leg volume increase was measured according to the formula of a truncated cone. Deep venous thrombosis was excluded by air plethysmography and colour-coded Duplex scanning. Lymphatic lesions were detected by lymphoscintigraphy using 99mTc labelled human serum albumin. MAIN RESULTS One week following vascular reconstruction the median leg volume increase was 24.5% in Group A vs. 23.3% in Group B (NS). Lymphoscintigraphy revealed obstruction of the lymphatics in five patients of Group A vs. three patients of Group B (NS). Neither the occurrence of lymph cysts nor extravasation of lymph differed between the two groups. In seven patients no lymphatic lesion was observed. Patients with interruption of the lymphatics (n = 8) had a higher leg volume increase compared to the remaining patients with no or minor lymphatic lesions, 31.2% vs. 19.6%, respectively (p < 0.05). CONCLUSIONS Leg oedema and the occurrence of lymphatic damage following femoropopliteal bypass surgery is not reduced by applying a lateral approach to the femoral artery in the groin. However, the higher leg volume increase in patients with lymphatic obstruction indicates that lymphatic damage could play a part in the leg oedema formation.

Causes of Cancellations on the Day of Surgery at Two Major University Hospitals

Cancellations of elective cases on the day of surgery waste valuable operating-room time. The authors studied cancellations at an American hospital and a Norwegian university hospital to test (a) whether the quality of hospital administrative data on cancellations is sufficient for meaningful comparative analysis and (b) whether causes of cancellations at these 2 major academic hospitals are comparable. Large retrospective cause-of-cancellation data sets were obtained from each hospital. The authors then prospectively established root causes of cancellations by on-site investigation and interviews of the hospital personnel involved. The surgical department at the Norwegian hospital cancelled 14.58% of cases in 2003 and 16.07% in 2004. The American hospital cancelled 16.52% of all cases between May 1, 2003, and April 30, 2004. Administrative data may give a rough picture of causes of cancellations. However, most findings at either of the hospitals do not translate easily to the other.