Aortic Arch Morphology and Aortic Length in Patients with Dissection, Traumatic, and Aneurysmal Disease.

OBJECTIVES: To assess aortic arch morphology and aortic length in patients with dissection, traumatic injury, and aneurysm undergoing TEVAR, and to identify characteristics specific to different pathologies. METHOD: This was a retrospective analysis of the aortic arch morphology and aortic length of dissection, traumatic injury, and aneurysmal patients. Computed tomography imaging was evaluated of 210 patients (49 dissection, 99 traumatic injury, 62 aneurysm) enrolled in three trials that received the conformable GORE TAG thoracic endoprosthesis. The mean age of trauma patients was 43 ± 19.6 years, 57 ± 11.7 years for dissection and 72 ± 9.6 years for aneurysm patients. A standardized protocol was used to measure aortic arch diameter, length, and take-off angle and clockface orientation of branch vessels. Differences in arch anatomy and length were assessed using ANOVA and independent t tests. RESULTS: Of the 210 arches evaluated, 22% had arch vessel common trunk configurations. The aortic diameter and the distance from the left main coronary (LMC) to the left common carotid (LCC) were greater in dissection patients than in trauma or aneurysm patients (p < .001). Aortic diameter in aneurysm patients was greater compared with trauma patients (p < .05). The distances from the branch vessels to the celiac artery (CA) were greater in dissection and aneurysm patients than in trauma patients (p < .001). The take-off angle of the innominate (I), LCCA, and left subclavian (LS) were greater, between 19% and 36%, in trauma patients than in dissection and aneurysm patients (p < .001). Clockface orientation of the arch vessels varies between pathologies. CONCLUSIONS: Arch anatomy has significant morphologic differences when comparing aortic pathologies. Describing these differences in a large sample of patients is beneficial for device designs and patient selection.

Morphometric analysis of the popliteal artery for endovascular treatment.

This study intended to determine the precise diameter of the popliteal artery in patients at risk for popliteal aneurysms. Accurate sizing is necessary to develop devices for endovascular treatment of popliteal aneurysms. Fifty-four patients with abdominal aortic aneurysms (AAAs) had computed tomography (CT) scans of the popliteal arteries. Age- and gender-matched control subjects were measured by ultrasound. NIH Image was used to measure the minor diameter at the adductor hiatus (proximal) and femoral condyles (midpopliteal artery). There were 4 unsuspected popliteal aneurysms (7.4%). The proximal popliteal artery was ectatic in these patients: 13.4 +/- 5.2 mm. Proximal and midpopliteal arteries were significantly larger in the other patients with AAAs compared with controls: 9.6 +/- 1.8 mm vs 7.9 +/- 1.1 mm at the hiatus (p<0.001) and 10.2 +/- 2 mm vs 7.9 +/- 0.9 mm at the condyles (p<0.001). The popliteal artery was focally larger in patients with AAAs without popliteal aneurysms. The popliteal artery was larger in men compared with women; 9.8 +/- 1.8 mm vs 8.8 +/- 1.9 mm at the hiatus (p=0.024) and 10.5 +/- 1.9 mm vs 9.0 +/- 2.4 mm at the condyles (p=0.005). The proximal popliteal artery was 2 mm larger in patients at risk for popliteal aneurysms and 5 mm larger in patients with popliteal aneurysms compared to controls. Focal ectasia of the midpopliteal artery was common. Planning for endovascular treatment of popliteal aneurysms must incorporate this striking enlargement.

Is bilateral ultrasound scanning of the legs necessary for patients with unilateral symptoms of deep vein thrombosis?

PURPOSE: The purpose of this study was to determine the necessity of bilateral lower-extremity venous duplex ultrasound scanning in patients with unilateral symptoms of deep vein thrombosis (DVT). PATIENTS AND METHODS: A retrospective review of 1080 bilateral venous duplex scans was performed. Patients were randomly selected from a total of 7922 studied between May 1998 and May 2000. Data on patient age, sex, comorbidity, and the reason for ultrasound scan were compiled. Forty percent (435/1080) of patients presented with unilateral symptoms of lower-extremity DVT. This group was further analyzed according to their status as inpatients or outpatients. RESULTS: DVT was diagnosed in 26.9% (117/435) of the patients. Of the inpatients found to have DVT, the thrombus was confined to the symptomatic leg in 23.8% (38/159), thrombus was present just in the asymptomatic leg in 8/159 (5.0%), and thrombus was found in both legs in 8/159 (5.0%). In the outpatient group, thrombus was confined to the symptomatic leg in 21.0% (58/276) and found in both legs in 1.8% (5/276). None of the 276 outpatients had DVT isolated in the asymptomatic leg. CONCLUSION: Routine bilateral lower-extremity venous duplex studies are not necessary in outpatients presenting with unilateral symptoms. In many outpatients, a single-limb study will suffice. If a patient is found to have a DVT on the symptomatic side, then we believe that a bilateral study is indicated. We do believe that routine bilateral scanning of inpatients remains justified. This algorithm may save technician time and increase vascular laboratory efficiency.

Mesenteric venous thrombosis: a changing clinical entity.

OBJECTIVE: Mesenteric venous thrombosis (MVT) and its clinical spectrum have become better defined following improvements in diagnostic imaging. Historically, MVT has been described as a morbid clinical entity, but this may not necessarily be true. Often, an underlying disease process that predisposes a patient to MVT can be found and potentially treated. This study was designed to evaluate the diagnostics and management of MVT and to review long-term results of treatment. PATIENTS: Thirty-one patients in whom MVT was diagnosed between 1985 and 1999 were retrospectively reviewed. Survivors were contacted for follow-up. There were 15 men and 16 women. Ages ranged from 22 to 80 years (mean, 49.1 years). Thirteen patients had documented hypercoagulability, 10 had a history of previous abdominal surgery, 6 had a prior thrombotic episode, and 4 had a history of cancer. MVT presented as abdominal pain (84%), diarrhea (42%), and nausea/vomiting (32%). Computed tomography (CT) was considered diagnostic in 18 (90%) of 20 patients who underwent the test. CT diagnosed MVT in 15 (100%) of 15 patients presenting with vague abdominal pain or diarrhea. Angiography demonstrated MVT in only five (55.5%) of nine patients. RESULTS: Seven of 31 patients died within 30 days (< 30-day mortality rate, 23%). Twenty-two patients (72%) were initially treated with heparin. Nine patients were not heparinized: four of them died, and two were later given warfarin sodium (Coumadin). Of the 31 patients, only one received lytic therapy. Three patients became symptom free without anticoagulation. Ten patients (32%) underwent bowel resection. Overall, 19 (79%) of 24 survivors were treated with long-term warfarin therapy. Long-term follow-up was obtained in 24 patients (mean, 57.7 months). Twenty-one (88%) of 24 survived in follow-up. CONCLUSION: The diagnosis of MVT should be suspected when acute abdominal symptoms develop in patients with prior thrombotic episodes or a documented coagulopathy. CT scanning appears to be the primary diagnostic test of choice. Anticoagulation is recommended. If diagnosed and treated early, MVT is not likely to progress to gangrenous bowel. Recent mortality rates for MVT are lower than previously published, perhaps because of earlier diagnosis and aggressive treatment or possibly because we now readily diagnose a more benign form of the disease, which is due to widespread use of CT scanning.

Screening and surveillance for abdominal aortic aneurysms: who needs it and when.

Early detection of abdominal aortic aneurysms potentially can save many lives by preventing aneurysm rupture. Screening programs, however, have yet to be proven as an efficient means of accomplishing this goal and improving overall life expectancy. Until more information is available, selective high-risk screening may be the only viable option. Recently, 2 large prospective studies have better defined the utility of screening programs and have provided guidelines for the safe nonoperative management of small aneurysms. Using ultrasound surveillance, these can be followed up at 3- to 12-month intervals, depending on their size, with operative intervention reserved for aneurysms that enlarge rapidly, become symptomatic, or reach 5.5 cm in diameter.

Identification and implications of transgraft microleaks after endovascular repair of aortic aneurysms.

PURPOSE: The purpose of this report is to describe an interesting cause of endoleak and detail-specific techniques for identifying small transgraft defects, which we have termed microleaks. METHODS: Four patients underwent endovascular repair of abdominal aortic aneurysms with modular nitinol/polyester endoprostheses and were studied after 6 to 30 months. All patients were enrolled in standard follow-up radiographic surveillance protocols. RESULTS: Three of the four abdominal aortic aneurysms continued to expand after endograft repair. Standard computed tomography imaging with precontrast, dynamic contrast, and delayed imaging frequently identifies endoleak, although it fails to precisely identify microleaks as the source. Color flow duplex ultrasound scan was performed on three patients and perigraft "jets," small areas of color flow adjacent to the endograft, were identified in all. Microleaks were identified in one patient who underwent digital subtraction arteriography with directed efforts to completely opacify the prosthesis lumen and multiple oblique projections. In another patient, contrast arteriography with balloon occlusion of the distal endograft clearly depicted midgraft microleaks that might otherwise be mistaken for graft porosity or cuff junction endoleaks. No microleaks were diagnosed on angiograms when these directed efforts were not performed. Aneurysm exploration before aortic clamping provided conclusive determination of the presence of blood flow through the wall of the endoprosthesis in two patients. CONCLUSIONS: Microleaks occur up to 2.5 years after endovascular repair of aortic aneurysms. Although computed tomography demonstrates the presence of an endoleak in these patients, the exact site of origin usually remains obscure. Doppler ultrasound scan and directed arteriography appear to be of greater utility for identifying the presence and location of microleaks. Balloon occlusion arteriography and aneurysm exploration without arterial clamping provide definitive evidence of microleaks. Although the clinical significance of microleaks remains unclear, long-term monitoring of patients is imperative to diagnose and treat these and other modes of endograft failure before they progress to aneurysm rupture.

Bedside vena cava filter placement guided with intravascular ultrasound.

OBJECTIVE: The purpose of this study was to report a feasibility trial approved by the Institutional Review Board for insertion of inferior vena cava (IVC) filters with intravascular ultrasound (IVUS) guidance in the intensive care unit. METHODS: Between October 1998 and May 2000, 26 patients (15 men, 11 women; age range, 22-86 years; mean, 55 years) were enrolled. Eight patients (31%) underwent prophylactic filter placement, and 18 patients (69%) had venous thromboembolism (deep venous thrombosis = 16, pulmonary embolism = 2) with contraindications to anticoagulation. A single groin puncture was used for IVUS and filter placement. Location of major branch veins, thrombosis, and caval diameter were readily demonstrated without the use of radiocontrast agents. Mapping of the IVC permitted assessment of ideal filter location. Postprocedure radiographs (23 of 26) were obtained to document filter position. Seventeen of 26 had follow-up lower extremity duplex studies. RESULTS: Twenty-four (92%) of 26 patients underwent successful filter deployment. The two other patients had filters subsequently placed by means of traditional fluoroscopic techniques. One femoral vein insertion site thrombosis resolved after a month. One patient experienced symptomatic caval thrombosis thought to be caused by thrombus trapping 55 days after the procedure. No pulmonary emboli occurred after filter placement. One patient's death was unrelated to vena cava filter placement. The hospital charge for bedside filters was $3623 compared with $4165 (P =.281) for fluoroscopic placement. CONCLUSION: Bedside insertion of an IVC filter with IVUS guidance is feasible and may be an effective alternative in the intensive care unit. No additional costs were incurred in this small series. Protocol refinements should reduce the incidence of complications. The results of this study support the need for further evaluation comparing it with standard techniques.

Update on the bifurcated EXCLUDER endoprosthesis: phase I results.

Many devices are being investigated for treatment of infrarenal abdominal aortic aneurysms. This report describes the particular characteristics of a next generation modular endograft and the Phase I results in 29 patients. Larger comparative studies are in progress to assess the safety and efficacy of this new design.

Incidental asymptomatic cerebral aneurysms in patients with extracranial cerebrovascular disease: is this a case against carotid endarterectomy without arteriography?

As less arteriography is performed before carotid surgery, concern arises about missing occult cerebral aneurysms and possible adverse outcomes. A study was conducted by the divisions of vascular surgery and neurosurgery of Northwestern University Medical School to evaluate the frequency of incidental cerebral aneurysms and outcomes of patients with extracranial cerebrovascular disease and asymptomatic cerebral aneurysms. From October 1995, through March 1997, 200 patients underwent intracranial and extracranial cerebrovascular angiography for evaluation of extracranial disease. Demographic data, symptoms, data of vascular lesions, surgical treatment and outcomes of stroke and death were recorded prospectively. Two patients (1%) had asymptomatic cerebral aneurysms found on angiography. Six more patients were referred with a known asymptomatic cerebral aneurysm with extracranial disease during this same period. Of these eight patients, five underwent extracranial vascular reconstruction surgery and seven received treatment for their aneurysms. There were two stroke complications, both occurred after treatment of a basilar artery aneurysm. One of these patients died. No aneurysms ruptured following 203 extracranial revascularizations during this same period. On the basis of the low prevalence of diagnosing coincidental cerebral aneurysms during work-up of extracranial disease, as well as the lack of evidence that carotid surgery predisposes to aneurysm rupture in these patients in both our study and the literature review, it is concluded that coexisting extracranial disease and asymptomatic cerebral aneurysms do not pose a case against carotid surgery without routine arteriography. However, arteriography should be considered in selected groups of patients where the yield of intracranial aneurysms is high; these include patients with a familial history of cerebral aneurysms, autosomal dominant polycystic kidney disease, extracranial internal carotid artery medial fibrodysplasia, Takayasu's arteritis, alpha1-antitripsin deficiency and atypical clinical presentations, including headache.

Filter placement by ultrasound technique at the bedside.

Vena cava filtration devices are commonly inserted for the prevention of fatal pulmonary emboli. Several imaging methods are used today to direct device placement. Bedside insertion has several advantages, particularly in the critically ill patient. Imaging techniques include bedside fluoroscopy, transperitoneal ultrasound, and intravascular ultrasound. We have now successfully placed 10 transfemoral vena cava filters by use of intravascular ultrasound at the patient's bedside. This appears to be a feasible method for filter insertion.

Transrectal ultrasound assessment of murine aorta and iliac arteries.

Recent research in arterial aneurysm formation has focused on animal model development. Mice are an ideal experimental organism due to their short life cycle, prolific progeny, and extensively studied genome. Most experiments require the sacrifice of the mice to observe and assess any morphological changes. Noninvasive or minimally invasive imaging is limited due to the relatively small size of the structures. The development of such a technique, therefore, is especially useful for allowing repeated measurement without sacrificing the mice. We introduce a novel technique of imaging and measuring the aorta, the aorta/inferior vena cava complex, and the right and the left common iliac artery/vein complex by the use of an intravascular ultrasound catheter. The catheter is inserted through the anus and rectum and into the sigmoid and left colon, where the aorta can be observed to fluctuate at approximately 500 beats/min. The aortic bifurcation can also be observed. The diameters of the aorta and the inferior vena cava were measured first with the transrectal ultrasound technique and then with direct visualization upon laparotomy for 10 mice. This revealed a percentage error between 13.7 and 14.2% for this novel technique. Fifteen more sets of vessel measurements were also made with 8 male and 7 female mice. The results demonstrated a correlation between vessel size and body weight in male but not female mice and suggested an intersex difference in vessel growth rate. We conclude that transrectal ultrasound is a useful tool in imaging and measuring the murine aorta and its bifurcation.

Development of echogenic, plasmid-incorporated, tissue-targeted cationic liposomes that can be used for directed gene delivery.

RATIONALE AND OBJECTIVES: Echogenic antibody-conjugated anionic liposomes have been developed that allow directed tissue targeting and acoustic enhancement. These are not efficient for gene delivery. A cationic formulation that allows directed gene delivery while retaining acoustic properties may provide more efficient transfection. METHODS: Cationic liposomes were prepared and acoustic reflectivity was determined. Anti-fibrinogen-conjugated liposomes were laid on fibrin-coated slides and adherence was quantified using fluorescence techniques. Liposomes were combined with a reporter gene and plated on cell cultures. Human umbilical vein endothelial cells were stimulated to upregulate intercellular adhesion molecule-1 (ICAM-1) and were treated with anti-ICAM-1-conjugated liposomes, and gene expression was quantified. RESULTS: Cationic liposomes retained their acoustic reflectivity and demonstrated specific adherence to fibrin under flow conditions. Significant transfection of human umbilical vein endothelial cells was demonstrated, with higher gene expression seen with specific antibody-conjugated liposomes. CONCLUSIONS: Novel acoustic cationic liposomes have been developed that can be antibody conjugated for site-specific adherence and directed cell modification. This presents exciting potential for a vector that allows tissue enhancement and targeted gene delivery.

Reoperative aortic surgery.

The presentation of long-term complications after conventional aortic surgery and the treatment of patients that have had reoperative aortic operations are reviewed. Ninety-seven consecutive patients that had 102 subsequent aortic operations at a tertiary referral center were studied. Presenting symptoms, demographics, risk factors, indications for initial and second procedures, operative techniques and outcomes were recorded in a computerized database. There were 70 men and 27 women studied, with an average age of 64 years. First operations were performed primarily for aneurysm (56%) and occlusive disease (44%). The interval between procedures ranged up to 23 years, with a mean of 6 years. Indications for reoperation were subsequent aneurysm (65), graft occlusions (25) and/or infections (24). Seventy-three percent of the subsequent aneurysms were true metachronous aneurysms; the others were associated with the graft or an anastomosis. Para-anastomotic aneurysms may be more common with a primary end-to-side graft configuration. One-third of subsequent aneurysms were not palpable and asymptomatic. Graft occlusion can be treated safely with elective repeat bypass (mortality 0%). Graft infections that require total graft removal remain a challenging problem (mortality 17%). Although surgical approach for reoperations utilized more extensive exposure and proximal clamping, 59 elective aneurysm cases had a 5.1% mortality rate; eight emergent procedures for ruptured aneurysms resulted in 88% mortality. Reoperation for graft occlusion or infection showed a similar high mortality rate with emergent cases. In this referral practice, graft occlusion and infection are relatively less frequent, whereas metachronous aneurysm formation is now the most common indication for reoperation. These aneurysms often remain undetected until symptoms occur; frank rupture is usually lethal. As elective repair with modern reoperative techniques can be safely performed, routine computed tomographic examination is advisable at least every 5 years after aortic operations.

Anatomic changes after endovascular grafting for aneurysmal disease.

Long-term follow-up of controlled clinical trials of endovascular grafting for aortic aneurysms will provide data on the safety and efficacy of this new treatment to reduce morbidity and mortality compared with standard treatment. It will be several years before this information will be available, and careful analysis of surrogate markers for clinical success has value for predicting long-term outcome. One essential surrogate marker is aortic aneurysm diameter, which has traditionally been the most important variable in calculating rupture risk, and multiple studies have shown that aneurysms shrink after complete endovascular exclusion. Furthermore, measurements of aortic neck size and aortic length has shown interesting patterns that may affect the durability of endovascular repair and, thus, may suggest potential strategies for the design of future devices.

Intravascular ultrasound-guided vena cava filter placement.

PURPOSE: To report a technique for the insertion of an inferior vena cava (IVC) filter under intravascular ultrasound (IVUS) guidance. TECHNIQUE: Using a Seldinger technique, a single groin puncture provides the access for IVUS interrogation of the IVC. After the anatomy is defined with IVUS, the same guidewire is used for percutaneous IVC filter insertion. Intraoperative fluoroscopy, used as a backup, corroborates the proposed insertion location before deployment of the device. Postoperative flat-plate abdominal radiographs are used to confirm satisfactory position. IVC filters have been successfully placed in 9 patients with no complications related to IVUS-guided insertion. CONCLUSIONS: Intraluminal IVC interrogation using IVUS is ideally suited for the proper deployment of an IVC filter. The deployment of IVC filters under IVUS has the potential to further simplify an established therapy for deep venous thrombosis and pulmonary embolism.

Characterization of vascular gene transfer using a novel cationic lipid.

INTRODUCTION: Cationic liposomes are an alternative non-viral vector for gene therapy, but several factors affect transfection efficiency. A novel cationic lipid, o-ethyldioleoylphosphatidylcholinium (EDOPC), was studied for characterization of the time course and effects of lipid composition, concentration, charge ratio, mixing techniques, passage number, and stimulated state on transfection of human vascular cells, represented by human umbilical vein endothelial cells (HUVEC). METHODS: HUVEC cultures were seeded at a density of 45,000 cells/well in 24-well plates and incubated overnight. Triplicate wells were transfected with samples of EDOPC/reporter plasmid for 2 h, followed by a 24-h expression time, which was the peak expression time point in an initial time-course experiment. Measuring luciferase in cell lysates quantitated gene expression. RESULTS: Transfection of HUVEC with EDOPC was optimal with a concentration of 100 microgram lipid/well, ratio of 3:1 EDOPC:plasmid, fractional mixing of lipid and plasmid, centrifugation, and incubation in serum-free media. Transfections in sequential passages showed striking decreases in gene expression and regression analysis revealed the relationship: RLU = 120,000 - (10, 400 x passage number), r(2) = 0.947. HUVEC activated by cytokine stimulation remain susceptible to gene transfer specifically with EDOPC. SUMMARY: During transfection of HUVEC with cationic lipid species, an increase in passage number is associated with linear reduction in luciferase expression, and hence passage number must be controlled in comparative experiments. Characteristics of EDOPC may permit site-specific efficient transfection of activated human vascular cells that can be isolated from serum by mechanical methods.

Natural history of composite sequential bypass: ten years' experience.

BACKGROUND: We previously reported 48-month patency rates of composite sequential bypass (CSB) approaching 60%. Yet, extended patency and limb salvage rates are unknown. HYPOTHESIS: Long-term patency and limb salvage rates of CSB are affected by sex, bypass configuration, and warfarin therapy. DESIGN: Medical records of all patients who underwent CSB during a 10-year period were retrospectively reviewed. SETTING: A referral center for the Chicago, Ill, region. PATIENTS: One hundred consecutive patients (mean age, 68.8 years; 57% were men and 49% had diabetes) undergoing 102 CSBs for limb salvage (ulcer, 43%; rest pain, 39%; and gangrene, 18%) from January 1986 to January 1996 were identified. INTERVENTIONS: Warfarin was used after surgery by 72% of patients and aspirin was used by the remainder of them. MAIN OUTCOME MEASURES: Life table primary patency and limb salvage rates were compared for sex, diabetes mellitus status, location of distal prosthetic anastomosis (above knee vs. below knee), and anticoagulation drug therapy (warfarin sodium vs aspirin) with log-rank statistics. RESULTS: Primary patency of CSB was 56% at 24 months, 29% at 48 months, and 20% at 84 months (SE <10%; mean follow-up, 19.6 months [range, 1.0-110.0 months]). Limb salvage rates were 64% at 24 months, 30% at 48 months, and 23% at 84 months (SE <10%); 66% and 90% of patients had failed grafts requiring amputation by 3 months and 1 year, respectively. CONCLUSIONS: Composite sequential bypass for limb salvage provides reasonable 2-year patency. However, patency rates steadily declined from year 2 to year 5. After CSB failure, limb salvage rates are poor, with 90% of patients progressing to amputation within 1 year.