An estimated prevalence of Johne's disease in a subpopulation of Alabama beef cattle

The objective of this study was to estimate the overall prevalence of animals that were infected with Mycobacterium avium ssp. paratuberculosis in a subpopulation of Alabama beef cattle. This was determined using a commercial enzyme-linked immunosorbent assay (ELISA) for the detection of M. avium ssp. paratuberculosis-specific antibodies in serum. Serum was collected from 79 herds that were participating in the Alabama Brucellosis Certification program. A total of 2,073 beef cattle were randomly tested by selecting 30 animals per herd in herds greater than 30 and selecting all animals in herds 30 and less for testing. It has been estimated that the commercial ELISA test used has a 60% sensitivity and a 97% specificity. Of the 79 herds tested, 29 herds were seronegative, 24 herds had 1-2 positive animals, and 26 herds had 3 or more seropositive animals. The average number of infected animals per positive herd was 3.3. In addition, a calculated minimum of 53.5% of the herds were identified as Johne's positive herds with a 95% confidence level. Of the total number of animals tested, 8.0% (166/2,073) of them were positive by the ELISA. After adjustments for test sensitivity and specificity and the proportion of animals sampled per herd, the true prevalence was calculated to be 8.75%. These data suggest that approximately 50% of the herds are infected with M. avium ssp. Paratuberculosis, and the overall prevalence of infection in Alabama beef cattle is approximately 8%, which correlates with other previously published regional estimates.

Increased flexibility of AneuRx stent-graft reduces need for secondary intervention following endovascular aneurysm repair

PURPOSE

To evaluate the impact of a change in the manufacturing of the AneuRx stent-graft on the long-term results of endovascular abdominal aortic aneurysm (AAA) repair.

METHODS

The first 70 AAA patients treated with the AneuRx stent-graft between October 1996 and December 1998 were reviewed. The early stiff bifurcated design (STIFF) was used in 23 patients (mean age 71.7 +/- 9.3 years, range 45-87) and the current flexible bifurcated design (FLEX) in 47 mean age 75.0 +/- 7.3 years, range 61-96). Data on patient demographics, aneurysm morphology, technical success, complications, secondary procedures, and outcomes were compared using Kaplan-Meier estimates to evaluate patient survival and freedom from surgical conversion, rupture, and secondary interventions at 6, 12, and 24 months.

RESULTS

The 2 groups were equally matched with regard to age, preoperative comorbidities, proximal neck dimensions, and aneurysm diameter. Mean follow-up times were 22.42 +/- 11.72 months (range 1-46) for the STIFF cohort and 18.08 +/- 6.14 months (range 1-30) for the FLEX (p = 0.057). Eleven (48%) of 23 STIFF patients required secondary interventions versus 6 (13%) of 47 FLEX patients (p < 0.05). There were no ruptures. At the 24-month interval, survival estimates were 86% for STIFF and 76% for FLEX (p = NS); freedom from surgical conversion was 100% for STIFF and 97% for FLEX (p = NS) and freedom from secondary interventions was 18% for STIFF and 90% for FLEX (p < 0.05) at 24 months.

CONCLUSIONS

The AneuRx stent-graft was effective in achieving the primary objective of preventing aneurysm rupture in all patients. However, increasing the flexibility of the bifurcated module significantly improved the primary success rate by reducing the need for subsequent secondary interventions.

Impact of endovascular repair on open aortic aneurysm surgical training

PURPOSE

The purpose of this study was to determine the impact of an endovascular stent-graft program on vascular training in open aortic aneurysm surgery.

METHODS

The institutional and vascular surgery fellow experience in aortic aneurysm repair during a 6-year period was reviewed. The 3-year period before introduction of endovascular repair was compared with the 3-year period after introduction of endovascular repair. All patients undergoing abdominal aortic aneurysm (AAA) or thoracoabdominal aortic aneurysm repairs were entered prospectively into a vascular registry and retrospectively analyzed to evaluate the changing patterns in aortic aneurysm treatment and surgical training.

RESULTS

Between July 1994 and June 2000, a total of 588 patients with AAA or thoracoabdominal aneurysms were treated at Stanford University Medical Center. There were 296 (50%) open infrarenal AAA repairs, 87 (15%) suprarenal AAA repairs, 47 (8%) thoracoabdominal aneurysm repairs, and 153 (26%) endovascular stent-grafts. The total number of aneurysms repaired per year by vascular fellows before the endovascular program was 71.3 +/- 4.9 (range, 68-77) and increased to 124.7 +/- 35.6 (range, 91-162) after introduction of endovascular repair (P <.05). This increase was primarily caused by the addition of endovascular stent-graft repairs by vascular fellows (51.0 +/- 29.0/year [range, 23-81]). There was no change in the number of open infrarenal aortic aneurysm repairs per year, 53.0 +/- 6.6 (range, 48-56) before endovascular repair versus 47.0 +/- 1.7 (range, 46-49) after (P = not significant). There was a significant increase in the number of suprarenal AAA repairs per year by vascular fellows, 10.0 +/- 1.0 (range, 9-11) before endovascular repair compared with 19.0 +/- 6.5 (range, 13-26) after (P <.05). There was no change in the number of thoracoabdominal aneurysm repairs per year between the two groups, 8.0 +/- 3.0 (range, 4-11) before endovascular repair compared with 7.6 +/- 2.3 (range, 5-9) after.

CONCLUSIONS

Introduction of an endovascular aneurysm stent-graft program significantly increased the total number of aneurysms treated. Although the number of open aneurysm repairs has remained the same, the complexity of the open aneurysm experience has increased significantly for vascular fellows in training.

Type-II endoleaks following endovascular AAA repair: preoperative predictors and long-term effects

PURPOSE

To determine the significance of persistent type-II endoleaks and whether they can be predicted preoperatively in patients with abdominal aortic aneurysms (AAA).

METHODS

The charts of all AAA patients treated with the AneuRx stent-graft at a single center from 1996 to 1998 were reviewed. Patients with <12-month follow-up or type-I endoleaks were excluded. The presence or absence of type-II endoleaks was determined from duplex imaging and computed tomographic angiography. Three groups were identified and compared: 16 patients with persistent type-II endoleaks (PE), 14 patients with transient type-II endoleaks (TE), and 16 patients with no endoleak (NE).

RESULTS

The groups did not differ with regard to age, preoperative comorbidities, follow-up time, and AAA neck diameter and length. AAA diameters were 57.1 +/- 9.0 mm for NE, 63.4 +/- 11.4 mm for TE, and 55.6 +/- 4.2 mm for PE. The inferior mesenteric artery (IMA) was patent in 5 (31%) NE patients, 6 (43%) TE patients, and 13 (81%) PE patients (p < 0.01). The number of patent lumbar arteries visualized preoperatively was 0.5 +/- 1.0 in NE, 1.3 +/- 0.8 in TE, and 2.4 +/- 0.6 in PE (p < 0.0001). Patent IMAs (RR 0.82, p < 0.01) and >2 lumbar arteries (RR 0.40, p < 0.0001) were identified as independent preoperative risk factors for persistent endoleaks. There were no changes in mean diameter or volume in aneurysms with persistent endoleaks.

CONCLUSIONS

No adverse clinical events were related to the presence of type-II endoleaks, but there was no decrease in aneurysm size in patients with persistent type-II leaks. Patients with a large, patent IMA, or >2 lumbar arteries on preoperative CT angiography are at higher risk for persistent type-II endoleaks.

Prediction of aortoiliac stent-graft length: comparison of measurement methods

PURPOSE

To determine the accuracy of helical computed tomography (CT), projectional angiography derived from CT angiography, and intravascular ultrasonographic withdrawal (IUW) length measurements for predicting appropriate aortoiliac stent-graft length.

MATERIALS AND METHODS

Helical CT data from 33 patients were analyzed before and after endovascular repair of abdominal aortic aneurysm (Aneuryx graft, n = 31; Excluder graft, n = 2). The aortoiliac length of the median luminal centerline (MLC) and the shortest path (SP) that remained at least one common iliac arterial radius away from the vessel wall were calculated. Conventional angiographic measurements were simulated from CT data as the length of the three-dimensional MLC projected onto four standard viewing planes. These predeployment lengths and IUW length, available in 24 patients, were compared with the aortoiliac arterial length after stent-graft deployment.

RESULTS

The mean error values of SP, MLC, the maximum projected MLC, and IUW were -2.1 mm +/- 4.6 (SD) (P =.013), 9.8 mm +/- 6.8 (P <.001), -5.2 mm +/- 7.8 (P <.001), and -14.1 mm +/- 9.3 (P <.001), respectively. The preprocedural prediction of the postprocedural aortoiliac length with the SP was significantly more accurate than that with the MLC (P <.001), maximum projected MLC (P <.001), and IUW (P <.001).

CONCLUSION

The shortest aortoiliac path length maintaining at least one radius distance from the vessel wall most accurately enabled stent-graft length prediction for 31 AneuRx and two Excluder stent-grafts.

Outcome after unilateral hypogastric artery occlusion during endovascular aneurysm repair

PURPOSE

The purpose of this study was to determine the long-term functional outcome after unilateral hypogastric artery occlusion during endovascular stent graft repair of aortoiliac aneurysms.

METHODS

During a 41-month period, 157 consecutive patients underwent elective endovascular stent graft repair of aortoiliac aneurysms with the Medtronic AneuRx device. Postoperative computed tomography scans were compared with preoperative scans to identify new hypogastric artery occlusions. Twenty-three (15%) patients had unilateral hypogastric occlusion, and there were no cases of bilateral occlusions. Telephone interviews about past and current levels of activity and symptoms were conducted, and pertinent medical records were reviewed. All 23 (100%) patients were available for the telephone interview. A disability score (DS) was quantitatively graded on a discrete scale ranging from 0 to 10 corresponding to "virtually bed-bound" to "greater-than-a-mile" exercise tolerance. Worsening or improvement of symptoms was expressed as a difference in DS between two time points (-, worsening/+, improving).

RESULTS

Among the 23 patients, two groups were identified: 10 patients (43%) had planned and 13 patients (57%) had unplanned or inadvertent occlusions. The patients in the two groups did not differ significantly in the mean age (73.4 vs 73.7 years), sex (male:female, 9:1 vs 10:3), and duration of follow-up (15.6 vs 14.4 months). Nine (39%) of the 23 patients, five patients in the planned and four patients in the unplanned group, reported significant symptoms of hip and buttock claudication ipsilateral to their occluded hypogastric arteries. The mean decrement from baseline of these nine patients in their DS postoperatively was -3.3. The symptoms were universally noted on postoperative day 1. Although most patients improved (89%), one (11%) never got better. Among those whose symptoms improved, the mean time to improvement was 15 weeks, but with a plateau thereafter resulting in a net decrement of DS of -2.3 from baseline. Finally, when questioned whether they would undergo the procedure again, all 23 patients unanimously answered, "Yes."

CONCLUSIONS

A significant number (39%) of patients who sustain hypogastric artery occlusion after endovascular aneurysm repair have symptoms. Although most patients with symptoms have some improvement, none return to their baseline level of activity. Despite this, all patients in retrospect would again choose endovascular repair over conventional open repair.

Eccentric stent graft compression: an indicator of insecure proximal fixation of aortic stent graft

PURPOSE

The purpose of this study was to determine whether radiographically demonstrated proximal stent graft contour can be used as a marker for security of proximal neck fixation after endovascular aneurysm repair.

METHODS

Stent graft structure was examined in 100 consecutive patients with abdominal aortic aneurysms who were treated with the stent graft. Stent graft integrity, stent contour, angulation, compression, and position were assessed by use of plain abdominal radiography, and the results were correlated with contrast computed tomography (CT) scanning, clinical findings, and outcomes. Repeated imaging was carried out during follow-up of 3 to 38 (mean, 12) months.

RESULTS

Stent graft repair was successful in all 100 patients. No stent fractures were identified. Concentric compression of the proximal portion of the stent graft was visible in 69% of patients and reflected deliberate oversizing of the stent graft at the time of implantation. In 5% of patients, a short eccentric compression deformity of the proximal stent was observed. This finding was associated with an increased risk of stent graft migration (P <.01) and with an increased risk for development of a late proximal (type I) endoleak (P <.01). Compared with CT scanning, abdominal radiography was less useful for assessment of short distances of migration (sensitivity 67%; specificity 79%). However, they provided better definition of the stent graft in relation to bony landmarks and better visualization of aortic calcification than CT with three-dimensional reconstruction.

CONCLUSION

Plain abdominal radiographs are important in the postoperative evaluation of patients with aortic stent grafts. They allow for more precise evaluation of the structural elements of the stent graft than CT scanning and may disclose inadequate proximal fixation by demonstration of an eccentric compression deformity. They are less useful for assessment of migration.

Duplex ultrasound scanning versus computed tomographic angiography for postoperative evaluation of endovascular abdominal aortic aneurysm repair

OBJECTIVE

The purpose of this study was to compare duplex ultrasound scanning and computed tomographic (CT) angiography for postoperative imaging and surveillance after endovascular repair of abdominal aortic aneurysm (AAA).

METHODS

One hundred consecutive patients with AAA underwent endovascular (Medtronic AneuRx, stent graft) aneurysm repair and were imaged with both CT angiography and duplex ultrasound scanning at regular intervals after the procedure. Each imaging modality was evaluated for technical adequacy and for documentation of aneurysm size, endoleak, and graft patency. In concurrent scan pairs, accuracy of duplex scanning was compared with CT.

RESULTS

A total of 268 CT scans and 214 duplex scans were obtained at intervals of 1 to 30 months after endovascular aneurysm repair (mean follow-up interval, 9+/-7 months). All CT scans were technically adequate, and 198 (93%) of 214 duplex scans were technically adequate for the determination of aneurysm size, presence of endoleak, and graft patency. Concurrent (within 7 days of each other) scan pairs were obtained in 166 instances in 76 patients (1-6 per patient). The maximal transverse aneurysm sac diameter measured with both methods correlated closely (r = 0.93; P <.001) without a significant difference on paired analysis. In 92% of scans, measurements were within 5 mm of each other. Diagnosis of endoleak on both examinations correlated closely (P <.001), and compared with CT, duplex scanning had a sensitivity of 81%, a specificity of 95%, a positive predictive value of 94%, and a negative predictive value of 90%. Discordant results occurred in 8% of examinations, and in none of these was the endoleak close to the attachment sites or associated with aneurysm expansion. An endoleak was demonstrated on both tests in all eight patients who had an endoleak judged severe enough to warrant arteriography. Graft patency was documented in each instance, without discrepancy, with both modalities.

CONCLUSIONS

High-quality duplex ultrasound scanning is comparable to CT angiography for the assessment of aneurysm size, endoleak, and graft patency after endovascular exclusion of AAA.

Will endovascular repair replace open surgery for abdominal aortic aneurysm repair?

OBJECTIVE

To evaluate of the impact of endovascular aneurysm repair on the rate of open surgical repair and on the overall treatment of abdominal aortic aneurysms (AAAs).

METHODS

All patients with AAA who were treated during two consecutive 40-month periods were reviewed. During the first period, only open surgical repair was performed; during the subsequent 40 months, endovascular repair and open surgical repair were treatment options.

RESULTS

A total of 727 patients with AAA were treated during the entire period. During the initial 40 months, 268 patients were treated with open surgical repair, including 216 infrarenal (81%), 43 complex (16%), and 9 ruptured (3%) aortic aneurysms. During the subsequent 40 months, 459 patients with AAA were treated (71% increase). There was no significant change in the number of patients undergoing open surgical repair and no significant difference in the rate of infrarenal (238 [77%]) and complex (51 [16%]) repairs. A total of 353 patients were referred for endovascular repair. Of these, 190 (54%) were considered candidates for endovascular repair based on computed tomography or arteriographic morphologic criteria. Analyzing a subgroup of 123 patients, the most common primary reasons for ineligibility for endovascular repair were related to morphology of the neck in 80 patients (65%) and of the iliac arteries in 35 patients (28%). A total of 149 patients underwent endovascular repair. Of these, the procedure was successful in 147 (99%), and 2 (1%) patients underwent surgical conversion. The hospital death rate was 0%, and the 30-day death rate was 1%. During a follow-up period of 1 to 39 months (mean 12 +/- 9), 21 secondary procedures to treat endoleak (20) or to maintain graft limb patency (1) were performed in 17 patients (11%). There were no aneurysm ruptures or aneurysm-related deaths.

CONCLUSIONS

Endovascular repair appears to have augmented treatment options rather than replaced open surgical repair for patients with AAA. Patients who previously were not candidates for repair because of medical comorbidity may now be safely treated with endovascular repair.

Endovascular repair of abdominal aortic aneurysms: eligibility rate and impact on the rate of open repair

OBJECTIVE

The purpose of this study was to determine the rate of eligibility among patients with abdominal aortic aneurysms (AAAs) considered for endovascular repair and to examine the effect of an endovascular program on the institutional pattern of AAA repair.

METHODS

All patients evaluated for endovascular AAA repair since the inception of an endovascular program were reviewed for determination of eligibility rates and eventual treatment. Open AAA repairs were categorized as simple (uncomplicated infrarenal), complex (juxtarenal, suprarenal, thoracoabdominal, infected), or ruptured, and their rates before and after initiation of an endovascular program were compared.

RESULTS

Over 3 years, 324 patients were considered for endovascular AAA repair; 176 (54%) were candidates, 138 (43%) were not candidates, and 10 (3%) did not complete the evaluation. The rate of eligibility increased significantly from 45% (66/148 patients) during the first half of this period to 63% (110/176 patients) during the second half (P <. 001). Candidates were significantly younger (74.4 +/- 7.6 years) than noncandidates (78.3 +/- 6.7 years) (P <.01), and their aneurysm diameter tended to be smaller (57.6 +/- 9.2 mm compared with 60.8 +/- 12.3 mm; P =.06). The most common reason for ineligibility was an inadequate proximal aortic neck. Of 176 candidates, 78% underwent endovascular repair, and 6% underwent open repair. Of 138 noncandidates, 56% underwent surgical repair. Over a period of 6 years, 542 patients with AAAs (429 simple, 86 complex, 27 ruptured) underwent open repair. The total number and ratio of simple to complex open repairs for nonruptured aneurysms during the 3 years before the initiation of the endovascular program (213 simple, 44 complex) were not significantly different from the repairs over the subsequent 3-year period (216 simple, 42 complex). Similarly, no difference in the total number and the ratio of simple to complex open repairs was found between the first and the second 18-month periods since the initiation of the endovascular program.

CONCLUSIONS

The rate of eligibility of patients with AAA for endovascular repair appears to be higher than previously reported. The presence of an active endovascular program has not decreased the number or shifted the distribution of open AAA repair.

Surgical intervention is not required for all patients with subclavian vein thrombosis

PURPOSE

The role of thoracic outlet decompression in the treatment of primary axillary-subclavian vein thrombosis remains controversial. The timing and indications for surgery are not well defined, and thoracic outlet procedures may be associated with infrequent, but significant, morbidity. We examined the outcomes of patients treated with or without surgery after the results of initial thrombolytic therapy and a short period of outpatient anticoagulation.

METHODS

Patients suspected of having a primary deep venous thrombosis underwent an urgent color-flow venous duplex ultrasound scan, followed by a venogram and catheter-directed thrombolysis. They were then converted from heparin to outpatient warfarin. Patients who remained asymptomatic received anticoagulants for 3 months. Patients who, at 4 weeks, had persistent symptoms of venous hypertension and positional obstruction of the subclavian vein, venous collaterals, or both demonstrated by means of venogram underwent thoracic outlet decompression and postoperative anticoagulation for 1 month.

RESULTS

Twenty-two patients were treated between June 1996 and June 1999. Of the 18 patients who received catheter-directed thrombolysis, complete patency was achieved in eight patients (44%), and partial patency was achieved in the remaining 10 patients (56%). Nine of 22 patients (41%) did not require surgery, and the remaining 13 patients underwent thoracic outlet decompression through a supraclavicular approach with scalenectomy, first-rib resection, and venolysis. Recurrent thrombosis developed in only one patient during the immediate period of anticoagulation. Eleven of 13 patients (85%) treated with surgery and eight of nine patients (89%) treated without surgery sustained durable relief of their symptoms and a return to their baseline level of physical activity. All patients who underwent surgery maintained their venous patency on follow-up duplex scanning imaging.

CONCLUSION

Not all patients with primary axillary-subclavian vein thrombosis require surgical intervention. A period of observation while patients are receiving oral anticoagulation for at least 1 month allows the selection of patients who will do well with nonoperative therapy. Patients with persistent symptoms and venous obstruction should be offered thoracic outlet decompression. Chronic anticoagulation is not required in these patients.

Rate of change in abdominal aortic aneurysm diameter after endovascular repair

OBJECTIVE

Untreated abdominal aortic aneurysms (AAAs) enlarge at a mean rate of 3.9 mm/y with great individual variability. We sought to determine the effect of endovascular repair on the rate of change in aneurysm size.

METHODS

There were 110 patients who underwent endovascular AAA repair at Stanford University Medical Center and who were followed up for 1 to 30 months (mean, 10 months) with serial contrast-infused helical computed tomography (CT). Maximal aneurysm diameter was determined using two independent methods: (1) measured manually, from cross-sectional computed tomography (XSCT) angiograms and (2) calculated from quantitative three-dimensional computed tomography (3DCT) data as orthonormal diameter.

RESULTS

Maximal cross-sectional aneurysm diameter measured by hand (XSCT) and calculated as orthonormal values (3DCT) correlated closely (r = 0.915; P <.001). The XSCT-measured diameter was larger by 2.3 +/- 3. 75 mm (P <.001), and the 95% CI for SE of the bias was 1.85 to 2.75 mm. Preoperative aneurysm diameter (XSCT 59.1 +/- 8.4 mm; 3DCT 58.1 +/- 9.3 mm) did not differ significantly from the initial postoperative diameter. Considering all patients, XSCT diameter decreased at a rate of 0.34 +/- 0.69 mm/mo, and 3DCT diameter decreased at a rate of 0.28 +/- 0.79 mm/mo. Aneurysms in patients without endoleaks had a higher rate of decrease, an XSCT diameter by 0.50 +/- 0.74 mm/mo, and 3DCT diameter by 0.46 +/- 0.84 mm/mo. In these patients, mean absolute decrease in diameter at 6 months was 3. 4 +/- 4.5 mm (XSCT) and 3.3 +/- 5.9 mm (3DCT) and at 12 months, 5.9 +/- 5.7 mm (XSCT) and 5.4 +/- 5.7 mm (3DCT). Aneurysms in patients with persistent endoleaks did not change in mean XSCT diameter, and 3DCT diameter increased by 0.12 +/- 0.52 mm/mo (not significant). Aneurysm diameter remained within 4 mm of original size in 68% (3DCT) to 71% (XSCT) of patients. In one patient, aneurysm diameter increased (XSCT and 3DCT) more than 5 mm. Four patients who had a new onset endoleak had a much higher expansion rate than those with a chronic endoleak (P <.05).

CONCLUSIONS

The rate of decrease in aneurysm size (annualized 3.4-4.1 mm/y) after endovascular repair of AAA approximates the reported expansion rate in untreated aneurysms. However, individual aneurysm behavior is unpredictable, and the presence of an endoleak is unreliable in predicting changes in diameter. New onset endoleaks are associated with an enlargement rate greater than that of untreated aneurysms.

Reoperation for carotid stenosis is as safe as primary carotid endarterectomy

PURPOSE

Patients with recurrent carotid artery stenosis are sometimes referred for carotid angioplasty and stenting because of reports that carotid reoperation has a higher complication rate than primary carotid endarterectomy. The purpose of this study was to determine whether a difference exists between outcomes of primary carotid endarterectomy and reoperative carotid surgery.

METHODS

Medical records were reviewed for all carotid operations performed from September 1993 through March 1998 by vascular surgery faculty at a single academic center. The results of primary carotid endarterectomy and operation for recurrent carotid stenosis were compared.

RESULTS

A total of 390 operations were performed on 352 patients. Indications for primary carotid endarterectomy (n = 350) were asymptomatic high-grade stenosis in 42% of the cases, amaurosis fugax and transient ischemic symptoms in 35%, global symptoms in 14%, and previous stroke in 9%. Indications for reoperative carotid surgery (n = 40) were symptomatic recurrent lesions in 50% of the cases and progressive high-grade asymptomatic stenoses in 50%. The results of primary carotid endarterectomy were no postoperative deaths, an overall stroke rate of 1.1% (three postoperative strokes, one preoperative stroke after angiography), and no permanent cranial nerve deficits. The results of operations for recurrent carotid stenosis were no postoperative deaths, no postoperative strokes, and no permanent cranial nerve deficits. In the primary carotid endarterectomy group, the mean hospital length of stay was 2.6 +/- 1. 1 days and the mean hospital cost was $9700. In the reoperative group, the mean length of stay was 2.6 +/- 1.5 days and the mean cost was $13,700. The higher cost of redo surgery is accounted for by a higher preoperative cerebral angiography rate (90%) in redo cases as compared with primary endarterectomy (40%).

CONCLUSION

In this series of 390 carotid operations, the procedure-related stroke/death rate was 0.8%. There were no differences between the stroke-death rates after primary carotid endarterectomy and operation for recurrent carotid stenosis. Operation for recurrent carotid stenosis is as safe and effective as primary carotid endarterectomy and should continue to be standard treatment.

Development of a minimally invasive technique for coronary revascularization in a porcine model

BACKGROUND

This porcine model was designed to develop a minimally invasive method for internal mammary artery (IMA) grafting using an anterior mediastinal approach and without routine use of cardiopulmonary bypass.

METHODS

Assessment was made of IMA mobilization through a small parasternal incision, the feasibility of coronary artery grafting with cardiopulmonary bypass using this approach, and conditions for off-pump bypass grafting.

RESULTS

In group 1, 6 pigs underwent IMA mobilization through a 5-cm horizontal midparasternal incision. Of the 2 group 2 pigs, 1 underwent IMA grafting to the left anterior descending coronary artery and the other, bilateral IMA grafting to the left anterior descending and right coronary arteries using femoral-vessel cardiopulmonary bypass. In group 3, 4 of 10 pigs had successful off-pump grafting during retrograde regional coronary venous perfusion of arterial blood. Retrograde coronary venous perfusion could not be established in the other 6 pigs, and attempts at off-pump grafting failed.

CONCLUSIONS

The study demonstrates that coronary artery grafting with the IMA by this minimally invasive off-pump method is feasible, although it draws attention to areas of concern and potential methods of correction. The model provides a realistic and important learning platform for the surgical issues involved with this minimally invasive technique.

Transient ventricular asystole using adenosine during minimally invasive and open sternotomy coronary artery bypass grafting

BACKGROUND

The emergence of minimally invasive coronary artery bypass grafting and recent off-pump open sternotomy clinical reports have refocused attention on the technical aspects and outcome of grafting on the beating heart.

METHODS

To optimize the surgical field we report a method using adenosine for induction of controlled intervals of ventricular asystole to produce a transiently still cardiac field that facilitates anastomotic accuracy.

RESULTS

Adenosine was used in 57 patients, 31 included off-pump coronary artery bypass grafting (27 by minimally invasive technique, 4 by open sternotomy). In a further 26 patients adenosine pauses were used for suture placement to control anastomotic bleeding after cardiopulmonary bypass. Average adenosine boluses per anastomosis were 9 (6-14), mean dose of adenosine per bolus (mg/kg) was 0.24 (0.15-0.35), mean duration of pause (seconds) was 6 (3-19), and mean time for arterial blood pressure (mean) to return to baseline (seconds) was 35 (13-48). Presence of repolarization arrhythmias was noted in 1 patient. There were no deaths. Two patients had recurrent myocardial ischemia shown on angiography to be the result of technical problems.

CONCLUSIONS

This report describes our experience with the emerging procedure of minimally invasive coronary operations and off-pump grafting with the adenosine technique. The method also includes mechanical devices and other pharmacological therapy to optimize the surgical field, and the technique has now become a standard component of our off-pump revascularization methods.

Endoscopic retrieval of severed flexor tendons: a study of technique using cadaveric hands

Retrieval of retracted zone 1, 2, and 3 flexor tendons without a proximal incision can occasionally lead to excessive tendon trauma or injury to neurovascular structures. To determine if endoscopic flexor tendon retrieval is a reliable, reproducible technique, 34 zone 2 flexor tendon lacerations were created in four cadaveric hands (2 male; 2 female). The tendons were retracted proximally an average of 4.3 +/- 1.9 cm (range, 2-10 cm) through a separate transverse wrist incision. A 2.5-mm flexible endoscope was introduced into the distal tendon sheath, and all transected tendons (N = 34) were clearly visualized. Thirty-two tendons (94%) were retrieved endoscopically by using either a loop snare or grasping forceps. Two tendons (6%) in a small female hand could not be retrieved endoscopically. This minimally invasive technique may be an alternative to the blind grasping maneuvers, proximal incision extensions, and counter-incisions in the palm.

Aortoscopy: a guidance system for endoluminal aortic surgery

PURPOSE

The aim of this project was to evaluate the feasibility of aortoscopy for guidance of endoluminal aortic procedures and to determine whether aortoscopy has advantages over fluoroscopy in a pig model.

METHODS

To establish feasibility aortoscopic guidance was used for making endoluminal aortic measurements, cannulating small arteries for arteriograpy, and placing intraaortic stents and grafts in 11 pigs. To compare aortoscopy and fluoroscopy measurements were made and stents were placed by a surgeon using only aortoscopic guidance in 10 pigs and by an interventional radiologist using only fluoroscopic guidance in 10 pigs. Postmortem dissections were performed to determine measurement and device placement accuracy.

RESULTS

In the feasibility study aortoscopic measurements differed from postmortem measurements by a mean distance (+/- SD) of 1.2 +/- 0.2 mm. Stents and grafts were placed a mean of 2.3 +/- 1.9 mm distal to the most inferior renal artery with no stent covering an orifice. All attempts at cannulating spinal arteries greater than 2 mm in diameter were successful. In the comparison of aortoscopic and fluoroscopic guidance, fluoroscopic measurements differed from postmortem measurements by 2.6 +/- 2.4 mm (p = 0.223). Stents placed with aortoscopic guidance were 1.1 +/- 1.3 mm distal to the most inferior renal artery, whereas stents placed with fluoroscopic guidance were 3.4 +/- 2.5 mm distal to the most inferior renal artery (p = 0.019).

CONCLUSIONS

These results demonstrate that aortoscopy is a useful guidance system for endoluminal aortic procedures and may have advantages over fluoroscopy alone.

Percutaneous dilational tracheostomy: report of 356 cases

OBJECTIVE

To evaluate the procedure time, complications, and percutaneous dilational tracheostomy (PDT) charges.

DESIGN

Operative data were prospectively collected for 356 PDTs including the initial series of 141 PDTs reported in 1994. Short- and long-term complications were retrospectively identified by review of medical records and patient telephone interviews.

MATERIALS AND METHODS

PDT was performed using the "Ciaglia" method of serial dilation over a Seldinger guidewire. Discharged patients (n = 258) were followed for a mean (+/-SD) of 10 +/- 7 months.

MEASUREMENTS AND MAIN RESULTS

The mean procedure time was 15 +/- 8 minutes; operative mortality rate, 0.3% (1/356); overall complication rate, 19% (69/356); long-term symptomatic tracheal stenosis rate, 3.7% (8/214). The mean total patient charge for bedside PDT was $1,370; for open tracheostomy in the operating room, $2,675.

CONCLUSIONS

Surgeons can rapidly perform PDT at the bedside with a lower risk of complications than open tracheostomy and at a significantly reduced patient charge.

Marjolin's ulcer of the foot caused by nonburn trauma

Marjolin's ulcers are malignancies that arise from previously traumatized, chronically inflamed, or scarred skin. We report a case of squamous cell carcinoma arising in a foot wound 42 years after the time of injury. The historical background, epidemiology, pathophysiology, diagnosis, treatment, and prognosis of Marjolin's ulcer are reviewed. Diagnosis is best accomplished by punch biopsy or excision of suggestive lesions. Wide local excision is required and amputation may be necessary to achieve an adequate margin. Regional lymph node dissection should be done if regional nodes are palpable. Elective lymph node dissection is controversial but should be considered if the tumor is poorly differentiated. Lymph node metastases and high tumor grade indicate a poor prognosis. Clinicians should be diligent in the long-term surveillance of all significant scars or areas of chronic inflammation.

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.

Intermittent sequential pneumatic compression in prevention of venous stasis associated with pneumoperitoneum during laparoscopic cholecystectomy

OBJECTIVES

To determine whether pneumoperitoneum and reverse Trendelenburg's position used during laparoscopy impede common femoral venous flow and whether calf-length intermittent sequential pneumatic compression (ISPC) overcomes this impedance.

DESIGN

Using Doppler ultrasonography, peak systolic velocities in the common femoral vein were measured in patients undergoing laparoscopic cholecystectomy with peritoneal insufflation of carbon dioxide. Measurements were obtained during three intervals: preoperatively with the patients in the supine position; after induction of general anesthesia with the patients in the supine position; and after insufflation to 13 to 15 mm Hg with the patients in the 30 degrees reverse Trendelenburg position (both with and without ISPC). Mean arterial pressure and heart rate were obtained concurrently. Measurements of preoperative and postoperative calf and thigh circumferences were obtained.

SETTING

A tertiary care center. PATIENT PARTICIPANTS: A consecutive sample of 20 patients 30 to 70 years of age (15 women and five men) who underwent laparoscopic cholecystectomy and met the inclusion criteria.

MAIN OUTCOME MEASURES

Peak systolic velocity, mean arterial pressure, heart rate, and calf and thigh circumferences.

RESULTS

The combination of pneumoperitoneum to 13 to 15 mm Hg and a 30 degrees reverse Trendelenburg position significantly decreased peak systolic velocity in the common femoral vein from a preoperative mean of 0.24 +/- 0.025 m/s to 0.14 +/- 0.011 m/s, or a 42% decrease. Intermittent sequential pneumatic compression reversed that effect, returning peak systolic velocity to 0.27 +/- 0.021 m/s. The mean difference between preoperative peak systolic velocity and peak systolic velocity with a combination of pneumoperitoneum, reverse Trendelenburg's position, and ISPC was 0.03 +/- 0.03 m/s but was not significant. Anesthesia alone caused a mean increase in preoperative peak systolic velocity from 0.24 +/- 0.025 m/s to 0.3 +/- 0.032 m/s. Mean arterial pressure levels, heart rate, and calf and thigh circumferences did not change significantly.

CONCLUSIONS

This study demonstrated a significant reduction in common femoral venous flow during laparoscopic cholecystectomy coincident with pneumoperitoneum and reverse Trendelenburg's position. Intermittent sequential pneumatic compression reversed that effect, returning peak systolic velocity to normal.