Accuracy of intravascular ultrasound for diameter measurement of phantom arteries.

BACKGROUND: Uniplanar quantitative angiography (QA) is the standard method for measuring vessel diameter during surgical and endovascular procedures. Intravascular ultrasound (IVUS), a relatively new technology, is another means of obtaining this measurement. This study was designed to validate the accuracy of these two modalities by comparing each to direct caliper measurement, the gold standard, using phantom femoral artery segments (PAS). MATERIALS AND METHODS: PAS diameter was measured with a 12.5-MHz mechanically rotating IVUS catheter (Boston Scientific Corp.) and QA (OEC Corp.) was compared to the direct caliper measurement (Mitutoyo Corp.) at 60 different locations within PAS. At each location minimal lumen diameter and perpendicular lumen diameter were measured and their mean was calculated. The intraclass correlation coefficients (ICCC) between direct caliper measurement and IVUS and uniplanar and biplanar angiography were calculated. Fisher's Z transformation was used to compare the correlation coefficients. RESULTS: The ICCC for IVUS was 0.89. The ICCCs for uniplanar and biplanar angiography were 0.73 and 0.82, respectively. IVUS correlated more closely with direct caliper measurement than uniplanar and biplanar angiography (P = 0.00008, 0.02) Biplanar angiography correlated more closely with direct caliper measurement than uniplanar angiography (P = 0.04). CONCLUSIONS: IVUS more accurately measures lumen diameter than uniplanar or biplanar angiography. Diameter measurement with biplanar angiography is more accurate than uniplanar angiography.

Identification of uric acid and xanthine oxidase in atherosclerotic plaque.

Concentrations of uric acid in carotid endarterectomy specimens in men and women were measured using high-performance liquid chromatography in comparison wo nonatherosclerotic control specimens.

Impaired venous hemodynamics in a minority of patients with chronic leg ulcers due to sickle cell anemia.

BACKGROUND: Chronic or recurrent leg ulceration occurs in 25% of sickle cell anemia patients, but not in the remaining 75%. Doppler studies of venous function were normal in 16 sickle cell anemia patients with leg ulcers. PATIENTS AND METHODS: Venous Duplex Ultrasound was used to study 33 sickle cell anemia patients with chronic leg ulcers. RESULTS: Six of the 33 patients had venous reflux in at least one leg. CONCLUSIONS: Venous insufficiency may contribute to the development of leg ulcers in a minority of sickle cell anemia patients. A minority of sickle cell anemia patients with chronic leg ulcers can be shown to have leg venous reflux by duplex ultrasound imaging.

Can preoperative spiral CT scans alone determine the feasibility of endovascular AAA repair? A comparison to angiographic measurements.

PURPOSE: To determine whether computed tomography (CT) alone can be used for excluding patients from endovascular repair for abdominal aortic aneurysms (AAA). METHODS: Among 71 patients evaluated for endovascular AAA repair using spiral CT imaging and angiography, 31 were selected who had both studies performed within 6 months of each other using a graduated measuring catheter or guidewire. Measurements of aneurysm neck diameter, neck length, and infrarenal aortic length were made from the CT and angiographic images using handheld calipers with calibration markers as guides. Infrarenal aortic length and neck length were determined from CT images by multiplying the width of the cuts by the number of slices between the lowest renal artery and the aortic bifurcation or the top of the aneurysm, respectively. RESULTS: CT neck diameter measurements differed significantly from the angiographic dimensions (6.3 +/- 5.1-mm mean difference, p < 0.001). In the majority of patients (25, 81%), CT neck diameters were larger (mean 7.3 +/- 3.8 mm). The mean difference in neck length measurements was 0.5 +/- 15.9 mm (p = NS). Twenty-two (71%) patients had aortic length measurements that were longer on the angiogram (mean 15.4 +/- 17.2 mm, p = NS). Five patients who would have been excluded as candidates based on overestimated CT neck diameter measurements subsequently underwent successful endovascular aneurysm repair. CONCLUSIONS: Considerable discrepancies exist between preoperative neck diameter and infrarenal aortic length measurements obtained from CT scans and angiograms used to evaluate candidates for endovascular aortic aneurysm repair. CT alone may not be adequate for predicting the feasibility of endovascular AAA repair.

Histology and electron microscopy of explanted bifurcated endovascular aortic grafts: evidence of early incorporation and healing.

PURPOSE: To report an examination of explanted bifurcated endovascular aortic grafts for histologic evidence of early healing and incorporation. METHOD: Two bifurcated endovascular aortic grafts composed of polycarbonate urethane and Elgiloy wire were explanted 42 and 21 days after successful endovascular exclusion of abdominal aortic aneurysms. Both patients expired from causes unrelated to endograft deployment. The explanted devices were examined using immunohistochemical analysis and electron microscopy. RESULTS: On explantation, both grafts appeared to have excluded the aneurysm with no evidence of endoleak, graft migration, or thrombosis. Histological examination showed numerous inflammatory cells and good ingrowth of tissue into the proximal 2 cm of the graft. Collagen and smooth muscle cells were evident in the proximal portion of the graft with only collagen in the distal segments. Neointimal formation was seen within the proximal 2 cm also, but not at the distal segments. Macrophages were present in the graft. Scanning electron microscopy showed an extensive matrix of fibers that most likely represented collagen. CONCLUSIONS: Bifurcated endovascular aortic grafts show inflammatory and mild foreign body reactions, collagen formation, and intimal ingrowth during healing. These findings are similar to some of the healing properties reported for sutured grafts, as well as other endovascular grafts.

Endoluminal repair of aneurysms containing ostia of essential branch arteries: an experimental model.

PURPOSE: To examine experimentally the feasibility of transfemoral endoluminal repair of aneurysms containing the ostia of essential branch arteries. METHODS: In a canine model (n = 4), suprarenal aortic aneurysms were created by suturing an artificial patch onto an anterior arteriotomy. Following a 2-week recovery period, the dogs underwent endovascular exclusion of their aneurysms using an aortic stent-graft with separate renal artery branch grafts. Outcome was evaluated using angiography, intravascular ultrasound (IVUS), Doppler flow, invasive pressure monitoring, and autopsy, respectively. RESULTS: Successful creation and subsequent endovascular exclusion of the aneurysm using aortic stent-grafts and separate bilateral renal artery stent-grafts was achieved in all trials. Angiographically, all aneurysms were excluded from aortic flow and all renal arteries were patent at completion of the procedure. With IVUS, good graft apposition and absence of perigraft flow were demonstrated in all animals. Mean pressure in the aneurysmal sac at completion of the procedure was 40 +/- 7 mmHg, compared to a mean systemic blood pressure of 105 +/- 8 mmHg (p < 0.05). At autopsy, no gross intimal damage was seen in the aorta or the renal arteries, and intact aortic grafts and branch grafts without twisting, coiling, or kinking were found in all trials. CONCLUSIONS: In an acute animal model, suprarenal aortic aneurysms can be excluded from the circulation with preservation of renal flow using an endoluminally placed aortic stent-graft with separate branch grafts.

Medium molecular weight pentastarch reduces reperfusion injury by decreasing capillary leak in an animal model of spinal cord ischemia.

PURPOSE: The medium molecular weight fraction of pentastarch (HES-Pz) has been shown to decrease reperfusion injury to myocardium and brain by reducing capillary leak. This study was undertaken to assess the effects of HES-Pz on neurologic function, microvascular permeability, and spinal cord infarction after temporary aortic cross-clamping in a rabbit model. METHODS: In 30 New Zealand White rabbits, a snare occlusion device was placed around the infrarenal aorta and tunneled into a subcutaneous position. Animals were allowed to recover for 48 hours and were randomized into three groups. In each group, the infrarenal aorta was occluded by tightening the snare in the awake animal for 21 minutes. Immediately after unclamping, animals received an intravenous infusion of 4% of their estimated blood volume of one of the following solutions: normal saline solution (NS; group 1); 6% standard hydroxyethyl starch (HES), molecular weight 10 to 3400 kD (group 2); and 6% HES-Pz, molecular weight 100 to 1000 kD (group 3). During 5 days of observation, neurologic recovery was graded by an independent observer using the Tarlov scale. Animals were then killed and their spinal cords harvested for histologic examination using hematoxylin-eosin and 2,3,5-triphenyltetrazolium chloride staining. In a separate group of animals (n = 15), the occurrence of spinal cord capillary permeability after NS, HES, and HES-Pz infusions was evaluated by spectrophotometric analysis of extravasated Evans blue. RESULTS: Complete paraplegia and marked histologic evidence of spinal cord cellular injury were seen in 90% of group 1 (NS) and in 78% of group 2 (HES). Treatment with HES-Pz (group 3) resulted in full neurologic recovery in 89% of animals (p < 0.05) and a threefold reduction of extravasated Evans blue compared with controls (p < 0.05). CONCLUSIONS: These results indicate that microvascular hyperpermeability plays an important role in reperfusion injury to the spinal cord. Treatment with HES-Pz reduced the capillary permeability, neuron membrane injury, and incidence of paraplegia after reperfusion of ischemic spinal cord in a rabbit model.

Combined carotid endarterectomy, innominate artery reconstruction, and coronary artery bypass grafting: case report.

Neurologic injury is one of the most devastating complications of combined carotid and cardiac procedures. Although the cause of the deficit is usually embolic, the exact cause is often not apparent at the time of surgery. We present a complex case of combined carotid endarterectomy, innominate artery reconstruction, and coronary artery bypass procedures in which intraoperative monitoring with somatosensory evoked potentials and transcranial Doppler ultrasonography combined with postoperative acetazolamide single photon emission computed tomographic scans was used to correlate intraoperative events with cerebral activity and functional results. Although computed tomographic scan, magnetic resonance imaging, and clinical evaluation were negative for any evidence of stroke, the patient exhibited subtle postoperative changes in neuropsychologic function. These changes were correlated with intraoperative microemboli detected by transcranial Doppler monitoring, and postoperative acetazolamide single photon emission computed tomographic scanning, which revealed bilateral cortical defects.

Surgical management of accessory parotid tumors.

Accessory parotid gland tumors are defined as masses within salivary gland tissue located adjacent to Stensen's duct, but separate from the main body of the parotid gland. These tumors usually present as asymptomatic cheek masses. There is a temptation to excise these masses locally; however, the likelihood of injury to branches of the facial nerve is high. The best surgical approach to tumors in the accessory parotid region is via a standard parotid incision and concomitant superficial parotidectomy. Eight patients have been surgically treated with accessory parotid gland masses. Six patients had mixed tumors, one had a low grade mucoepidermoid carcinoma, and one had a localized parotitis. Our approach included a standard parotid incision, raising an anterior flap beyond the mass, and exposing the main trunk of the facial nerve, with careful tracing of all its branches. This approach to accessory parotid gland tumors is superior in that it provides a better margin of resection and minimizes functional and cosmetic deformities. Most importantly, there is less danger of injury to branches of the facial nerve.