Endothelial cell adaptation to chronic thrombosis.

BACKGROUND: The autogenous vein graft has proven to be the most durable conduit in lower extremity vascular bypass grafts. Failures due to thrombosis, intimal hyperplasia, and progression of atherosclerotic disease commonly plague the vascular surgeon. Part of the ability of vein grafts to provide a nonthrombogenic surface relies on the capability of the endothelial cell to produce prostacyclin, a potent vasodilator and inhibitor of platelet aggregation. Once a graft fails and thromboses, little is known as to the effects of the thrombus on the function and morphology of endothelial cells. Earlier studies by this laboratory demonstrated the ability of arterialized canine vein grafts to recover function after 5 days of exposure to thrombus. This investigation sought to explore the limits of endothelial cell viability and recovery to extended periods of thrombosis. METHODS: Using a canine model of arterialized vein grafts, prostacyclin production (measured as 6-keto-PGF1a) was assessed in an ex vivo perfusion system from grafts exposed to thrombus for 10 days (group I) and 20 days (group II). Both groups underwent thrombectomy and a recovery period of 30 days. The grafts were perfused with Hanks' balanced salt solution and samples were obtained at 5 and 30 minutes to determine prostacyclin levels. Arachidonic acid was then added to a new perfusate of Hanks' solution and samples were again obtained at 5 and 30 minutes. Results were expressed as PGF/graft area (cm2/min). Representative samples of each graft underwent scanning electron microscopy. RESULTS: Without arachidonic acid, prostacyclin production of group II (20 day) grafts was greater than group I (10 day) grafts at 5 minutes of perfusion (4.31 versus 2.42, P = 0.08) and at 30 minutes (1.86 versus 0.95, P = 0.02). In response to the addition of arachidonic acid both groups increased prostacyclin production (group I, P = 0.004; group II, P = 0.12). A comparison was made between prostacyclin production at baseline and after addition of arachidonic acid. Group I grafts demonstrated a greater percent increase in prostacyclin production compared to group II (385% versus 229%, P = 0.01). Scanning electron microscopy showed no differences in endothelial coverage between the study groups. CONCLUSIONS: These results demonstrate that although endothelial cells are able to recover a basal level of prostacyclin production, the response to substrate stimulation diminishes with increased exposure time to thrombus. This diminished response may be important in understanding the ability of vein grafts to survive after a period of thrombosis.

Resumption of menses in anorexia nervosa.

OBJECTIVE: To determine factors associated with resumption of menses (ROM) in adolescents with anorexia nervosa. DESIGN: Cohort study with 2-year follow-up. SETTING: Tertiary care referral center. PATIENTS: Consecutive sample of 100 adolescent girls with anorexia nervosa. INTERVENTIONS: Body weight, percent body fat, and luteinizing hormone, follicle-stimulating hormone, and estradiol levels were measured at baseline and every 3 months until ROM (defined as 2 or more consecutive spontaneous menstrual cycles). Treatment consisted of a combination of medical, nutritional, and psychiatric intervention aimed at weight gain and resolution of psychological conflicts. MAIN OUTCOME MEASURES: Body weight, body composition, and hormonal status at ROM. RESULTS: Menses resumed at a mean (+/-SD) of 9.4 +/- 8.2 months after patients were initially seen and required a weight of 2.05 kg more than the weight at which menses were lost. Mean (+/-SD) percent of standard body weight at ROM was 91.6% +/- 9.1%, and 86% of patients resumed menses within 6 months of achieving this weight. At 1-year follow-up, 47 (68%) of 69 patients had resumed menses and 22 (32%) remained amenorrheic. No significant differences were seen in body weight, body mass index, or percent body fat at follow-up in those who resumed menses by 1 year compared with those who had not. Subjects who remained amenorrheic at 1 year had lower levels of luteinizing hormone (P < .001) and follicle-stimulating hormone (P < .05) at baseline and lower levels of luteinizing hormone (P < .01) and estradiol (P < .001) at follow-up. At follow-up, a serum estradiol level of more than 110 pmol/L (30 pg/mL) was associated with ROM (relative risk, 4.6; 95% confidence interval, 1.9-11.2). CONCLUSIONS: A weight approximately 90% of standard body weight was the average weight at which ROM occurred and is a reasonable treatment goal weight, because 86% of patients who achieved this goal resumed menses within 6 months. Resumption of menses required restoration of hypothalamic-pituitary-ovarian function, which did not depend on the amount of body fat. Serum estradiol levels at follow-up best assess ROM.

Ultrasound-guided pseudoaneurysm compression: efficacy after coronary stenting and angioplasty.

PURPOSE: Ultrasound-guided compression of femoral pseudoaneurysms has often obviated the need for open operative repair. Increasing use of percutaneous interventional cardiac procedures has created pseudoaneurysms with a large-caliber arterial defect, often in patients who are placed immediately on anticoagulation therapy. This report describes the prospectively collected information from our vascular laboratory regarding ultrasound-guided compression of these pseudoaneurysms after cardiac procedures, both interventional and diagnostic. METHODS: Since March 1994 prospective data collection for patients who have undergone pseudoaneurysm compression in our vascular laboratory has recorded information including cardiac procedure, size of catheter or sheath, coagulation parameters, pseudoaneurysm size and location, and time to compression. Forty-one patients underwent attempted ultrasound-guided pseudoaneurysm compression after cardiac procedures: 19 after cardiac catheterization alone, seven after angioplasty, one after atherectomy, two after insertion and subsequent removal of an intraaortic balloon pump, and 12 after coronary stenting. RESULTS: Compression was successful overall in 88% of the patients (36 of 41). Successful compression of the pseudoaneurysm was seen in 95% after catheterization alone, 100% after angioplasty, 100% after atherectomy, and 100% after intraaortic balloon pumping, as compared with 67% after stenting (eight of 12 vs 28 of 29; p = 0.02). A sheath size of 9F or greater was a significant factor in predicting unsuccessful compression (three of eight vs two of 33; p = 0.04). Abnormal coagulation parameters were present in 20 of the 41 patients and was not significantly different in patients who were successfully or unsuccessfully treated (four of five vs 16 of 36; p = 0.40). CONCLUSIONS: Pseudoaneurysms after cardiac procedures and interventions can often be successfully compressed with an ultrasound-guided technique. The presence of abnormal coagulation parameters was not identified as a risk factor for compression failure and should not dissuade attempted compression. Stent placement was more likely to result in unsuccessful compression, and this appeared to be a result of the larger size of the arterial defect. Even in this setting, compression achieved obliteration of the pseudoaneurysm in more than half of the patients.

The effect of thrombus on the vascular endothelium of arterialized vein grafts.

BACKGROUND: It is known that vein grafts can be salvaged by clot removal, but patency rates are diminished. This study was designed to determine the effects of thrombus on vascular endothelium and the ability of the endothelium to recover normal function. METHODS: Thirty external jugular vein grafts were placed as bilateral femoral artery interposition grafts in 15 mongrel dogs and allowed to arterialize for a period of at least 12 weeks. Six control grafts were not exposed to thrombus (C-NT). Six other control grafts were exposed to thrombus for 7 days and removed, ie, allowed no in vivo recovery (C-T). The remaining 18 grafts in 9 canines were exposed to autologous thrombus for 5 days and then flow was restored. The right femoral graft was removed 7 days after thrombectomy and the left removed 30 days after thrombectomy. At the time of removal, the grafts were perfused with a balanced salt solution alone and then with arachidonic acid added to the same volume of the salt solution. Perfusates were collected at 5, 15, and 30 minutes. These perfusates were assayed for the presence of 6-keto-prosglandin F1 alpha (6-keto-PGF1(1 alpha)), a metabolite of prostacyclin (PGI2). Over the 30-day recovery period, the amounts of 6-keto-PGF1(1 alpha) produced with and without arachidonic acid added were compared to assess endothelial response. Electron micrographs of the endothelium of all vein grafts were compared to the assay findings. RESULTS: When arachidonic acid was added to the perfusion system, there was a several fold increase in the production of 6-keto-PGF1(1 alpha) over baseline in all grafts allowed recovery. Grafts (C-T) that were allowed no in vivo recovery had no response to arachidonic acid. Ratios of 6-keto-PGF1(1 alpha) production with arachidonic acid stimulation to 6-keto-PGF1(1 alpha) production without stimulation were calculated to compare endothelial function. The electron micrographs showed the vascular endothelium to be severely injured after contact with thrombus, but recovered by 7 days. CONCLUSIONS: This study suggests that the endothelium of canine vein grafts is injured by contact with thrombus for 5 days but can recover structure and function. This recovery is detectable at 7 days post-thrombectomy.

Evaluation of renal artery stenosis by magnetic resonance angiography.

BACKGROUND: Accurate identification of patients with surgically correctable renovascular hypertension has been difficult by noninvasive means. Advances in the technique of magnetic resonance angiography (MRA) have begun to provide detailed, accurate imaging of the vascular system. This study reports our recent experience in the evaluation of the renal arteries by this technique. METHODS: MRA and contrast arteriography were performed in 32 arteries (16 adult patients) for evaluation of hypertension, abdominal aortic aneurysm, mesenteric vascular disease, and aorto-iliac occlusive disease. Luminal diameter reduction (%) was determined from two-dimensional time-of-flight (TOF) axial images. Contrast arteriography served as the gold standard for comparison. RESULTS: Contrast arteriography revealed a 50% or greater stenosis in 11 of 32 vessels studied (34%). As a screening test for detection of greater than 50% diameter reduction, MRA had a sensitivity of 91%, a negative predictive value of 94%, and an overall accuracy of 81%. Linear regression analysis demonstrated significant correlation between MRA and arteriographic measurements (r = 0.8; P < 0.001). CONCLUSIONS: This study demonstrates the ability of MRA to accurately assess the main renal arteries for the presence of critical stenosis. This noninvasive evaluation compares well with conventional angiography and may have increasing application in the screening of patients with suspected renovascular disease.

Magnetic resonance angiographic imaging of angioplasty and atherectomy sites.

UNLABELLED: Magnetic resonance angiography (MRA) provides detailed morphologic and flow information that demonstrates complex changes at sites of percutaneous transluminal angioplasty (PTA) and atherectomy. The purpose of this study is to examine the appearance of the vessel by MRA in the initial post-procedural and early follow-up periods. METHODS: MRA was performed to evaluate 35 infrainguinal endovascular procedures (20 patients), including PTA (20), atherectomy (4), and combination PTA/atherectomy (11). MRA imaging was performed within 24 hours of the procedure and at a mean follow-up interval of 3.5 months (range 1-8). RESULTS: Abnormalities in the immediate post-procedural MRA were seen in 55% of the PTA group and 93% of the atherectomy group (p = 0.04). Importantly, three of 35 lesions (9%) were shown by MRA to harbor > 50% stenoses despite angiographically "successful" procedures. Follow-up MRA showed abnormalities in 25% of those undergoing PTA, and in 67% of those with atherectomy (p = 0.01). At the time of follow-up MRA, four areas showed > 50% stenosis and four areas showed occlusion, revealing unfavorable outcomes in 22%. CONCLUSIONS: MRA provides a detailed noninvasive image of the sites of endovascular interventions and reveals vessel wall abnormalities not appreciated by conventional arteriography. Continued observation may allow prediction of segments at increased risk for restenosis.

Comparison of magnetic resonance angiography and contrast arteriography in peripheral arterial stenosis.

Magnetic resonance angiography (MRA) has recently been shown to be more sensitive than contrast arteriography in the detection of patent distal runoff vessels. This study compares MRA and contrast arteriography in evaluating the severity of stenotic lesions in peripheral arteries, which has not been previously investigated. Forty-eight arterial stenoses (19 patients) were identified, from the distal aorta through the crural vessels. Contrast arteriograms (anterioposterior projection) and MRA axial images were used to measure stenoses. Interobserver agreement of arteriogram readings was excellent (average weighted k = 0.87). Measurements of degree of stenosis as evaluated by MRA and contrast arteriography were analyzed by linear regression and Spearman rank correlation, which showed a high degree of correlation between the two diagnostic modalities (r = 0.83, p < 0.001; rs = 0.84, p < 0.001). These observations suggest that MRA is accurate in the evaluation of peripheral arterial stenosis when compared with the "gold standard" contrast arteriogram. In addition, MRA cross-sectional images provide information beyond that of conventional arteriography, showing details of plaque eccentricity and vessel wall characteristics. In the future, MRA may supplant diagnostic contrast arteriography for many patients.

The role of the psychiatrist in otolaryngology.

The patient, staff, and physician benefit when the otolaryngologist and psychiatrist are able to work closely together. Not only is clinical care improved, but time can be spent more efficiently in dealing directly with the patient's problem.