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Biomedical subjects

D W Hunter

Publications and source records attributed to D W Hunter.

At least 91 records · Page 5Linked to original sources
PubMed1989

Mechanical clot dissolution: new concept.

The authors present preliminary data on in vitro mechanical clot dissolution by means of a catheter with a tiny high-speed propeller enclosed in a special housing. Preweighed human blood clots were subjected to the catheter in a test tube with saline at various propeller speeds and durations of application. After filtration of the resultant slurry, the clot residue was weighed and examined histologically. Clot dissolution was found to be related to both the duration and speed of propeller rotation. No fibrin residue was seen after dissolution, although potential embolic material, composed of clumps of cellular debris as large as 208 microns in longest dimension, was found. Mechanical clot dissolution could possibly be used in any natural or synthetic blood vessel in which there is acute or subacute thrombosis, with fewer complications and lower cost than obtained with traditional methods.

Catheterization↗
PubMed1989

Thrombosed polytetrafluoroethylene hemodialysis fistulas: salvage with combined thrombectomy and angioplasty.

Combined thrombectomy and angioplasty was performed for 19 thrombosed polytetrafluoroethylene grafts. Patency for more than 1 week was achieved in 16 of the 19 grafts (84%). The average duration of graft function after angioplasty in all 19 grafts was 7.1 months (range, 0-32.3 months). Eleven of the 19 grafts (58%) were functioning 5 months after the procedure; seven are still functioning. Combined thrombectomy and angioplasty offers a viable alternative to thrombolytic therapy or complete surgical revision.

Adult↗
PubMed1989

Experience with the Amplatz retrievable vena cava filter.

The Amplatz retrievable inferior vena cava filter was designed to be used as either a permanent indwelling filter or a short-term, percutaneously removable filter. The authors placed 52 filters in 52 patients. No deaths occurred as a result of filter placement or usage. Follow-up in 42 (81%) patients included inferior vena cavography (n = 31), computed tomography (n = 4), duplex ultrasound (n = 4), and autopsy (n = 3). Inferior vena cava thrombosis was found in seven (17.5%) of the 40 previously nonobstructed venae cavae studied. Two patients with caval thrombosis required a second filter to prevent embolization of thrombus that had extended to the lung side of the first filter. No clinically evident pulmonary emboli after filter placement have been noted. Six filters were successfully retrieved or repositioned percutaneously. The relatively high rate of caval thrombosis with extension above the filter may be due to a higher trapping efficiency or to filter geometry. The role of this filter in the treatment of deep venous thrombosis and pulmonary emboli is unclear.

Adult↗
PubMed1989

Incidental fibromuscular dysplasia in potential renal donors: long-term clinical follow-up.

The clinical natural history of renal arterial fibromuscular dysplasia (FMD) in patients with normal blood pressure is unknown, to the authors' knowledge. The authors reviewed the results of 1,862 renal angiograms obtained in potential renal donors. FMD was present in 71 patients (3.8%). The average age at which FMD was discovered was 50.8 years. Seventy-five percent of the patients with FMD were female. Of 30 patients who did not undergo nephrectomy, eight (26.6%) developed hypertension over a mean followup interval of 7.5 years. Of 19 patients who underwent nephrectomy, despite the presence of FMD, five (26.3%) developed hypertension over a mean follow-up interval of 4.4 years. In comparison, three subjects (6.1%) (from a randomized control group of 49 age- and sex-matched healthy individuals) developed hypertension over a mean follow-up period of 7.1 years. The authors conclude that asymptomatic middle-aged individuals with renal FMD develop hypertension at a rate greater than that of age-matched control subjects with normal blood pressure.

Adult↗
PubMed1989

Double-lumen needle for percutaneous ureteral pressure-flow studies.

Ureteral perfusion studies in patients without preexisting renal access currently must be intermittently interrupted for intrarenal pressure measurement. A double-lumen needle has been successfully placed in four patients (two with native and two with transplanted kidneys). This permits simultaneous perfusion and intrarenal pressure monitoring yet maintains the safety and ease of use of a single skinny needle.

Humans↗
PubMed1989

Aid for safer sclerotherapy of the internal spermatic vein.

A device was developed for use during sclerotherapy to treat spermatic varicoceles. It is used to provide external compression of the internal spermatic vein, to prevent distal flow of the sclerosing agent into the scrotal venous network. The device has been successfully used in 27 patients (43 spermatic veins). In no case did sclerosing agent leak past the compressor, and no complications related to the compressor itself have been encountered.

Equipment and Supplies↗
PubMed1989

Retrograde left atrial catheterization.

Catheterization of the left atrium can provide valuable information about both congenital and acquired heart disease. The traditional approach to examination of the left atrium has been the transseptal route, which has occasionally been associated with serious complications. A method of retrograde left atrial catheterization has been developed that is performed with a modified standard catheter. The technique was tested in five dogs and was easy and safe to perform.

Animals↗
PubMed1989

The importance of separation of prostatic lobes in relief of prostatic obstruction by balloon catheter urethroplasty: studies in dogs and humans.

We performed balloon urethroplasty in six older normal dogs and 10 patients with benign prostatic hypertrophy to establish the mechanism by which this technique results in relief of bladder outlet obstruction. Thirty-millimeter balloon catheters were used in both the animal and human studies. Autopsy studies showed disruption of the anterior prostatic commissure in four of the six dogs, disruption of both anterior and posterior commissures in one dog, and no disruption in the remaining dog. In all 10 patients, cystoscopy and urethrography showed disruption of the anterior commissure. Separation of the prostatic lobes by disruption of the prostatic commissures may be the most important mechanism by which balloon urethroplasty relieves urethral obstruction.

Animals↗
PubMed1989

Transplant renal artery stenosis.

A group of 31 patients with transplant renal artery stenoses was identified among 2002 patients undergoing renal transplantation at the University of Minnesota; 29 of the stenoses were at the anastomosis. A total of 43 procedures were performed to correct the stenosis. Angioplasty was performed 25 times, with 3 patients cured and 2 patients improved; 20 procedures resulted in a poor result (3) or a failure (17). The failures were usually due to recurrent stenosis (7 patients) or to arterial injury that resulted in graft loss (4 patients) or successful emergency surgery to save the transplant (3 cases). Surgical repair of the stenosis was performed 18 times. No grafts were lost and 13 patients were cured or improved. These data suggest that angioplasty for anastomotic stenosis yields poor results and that a surgical repair is probably warranted. All 7 patients who had a poor results or failed a technically successful intervention did not have a rise in creatinine secondary to captopril or had a systolic pressure gradient of less than 60 mmHg across the anastomosis. These data also suggest that patients without physiological evidence of renal artery stenosis may not have improvement in their hypertension following repair.

Angioplasty, Balloon↗
PubMed1988

Using a symbiotic man/machine approach to evaluating visual clinical research data.

Some candidate medical expert system applications have a significant visual component. Knowledge engineers usually dismiss such task domains as potential expert systems applications. Our success in developing ESCA, a system for evaluating serial coronary angiograms, shows that such task domains should not be dismissed so quickly. We used a symbiotic approach between man and machine, where technologists provide the visual skills with an expert system imitating the conceptual skills of the expert, to produce a partially automated system that is more consistent and cost effective than one that is fully manual. The agreement between the system's conclusions and that of a panel of experts is good. The expert system actually has a slightly higher agreement rate with the expert panel than the agreement rate between two expert panel teams evaluating the same film pair.

Angiocardiography↗
PubMed1988

In vitro evaluation of caval filters.

This experiment demonstrated the clottrapping ability of two commercially available filters, the Mobin-Uddin and Greenfield, and three experimental filters developed by Amplatz, Günther, and Gianturco. Each filter was tested in a polyethylene tube simulating the inferior vena cava. Separate series of 10 clots, each 3 cm long and 6 mm or 9.2 mm in diameter, were exposed to the test filter. The Mobin-Uddin and Amplatz filters failed by overload: acutely elevated pressures forced clots outside the skirt of the former, and between the limbs of the latter. The Günther filter trapped all incident clots, but migrated downstream when occluded by clot. The Greenfield filter passed clots at normal pressures between its widely spaced legs. The Gianturco (bird's nest) passed clots at normal pressures as well. While filters performed suboptimally, strengthening the anchoring struts of the Günther filter would result in a secure, effective filter.

Animals↗
PubMed1988

Biliary complications after liver transplantation in patients with preexisting sclerosing cholangitis.

To determine if biliary complications after liver transplantation are more frequent in patients with preexisting sclerosing cholangitis and to clarify the role of interventional procedures in this setting, the authors reviewed all 40 adult cases in which liver transplantation was performed at their institution over a 3 1/2-year period. Biliary complications, particularly strictures at the choledochojejunostomy and debris in the intrahepatic and common ducts, were seen in six of ten liver transplant patients (60%) with preexisting sclerosing cholangitis; this is six times the frequency of biliary complications seen in other adult recipients (10%). Biliary complications were definitively diagnosed and managed with interventional radiologic procedures. Obstruction due to anastomotic strictures required treatment with balloon dilation in all six of the affected patients. Obstructive biliary complications occur in many liver recipients with preexisting sclerosing cholangitis. These complications require aggressive radiologic assessment and intervention but to date have not adversely affected survival.

Adult↗
PubMed1988

Lower-extremity venous thrombosis: comparison of venography, impedance plethysmography, and intravenous manometry.

This study was undertaken to compare impedance plethysmography with lower-extremity venography and venous manometry in the diagnosis of acute deep venous thrombosis (DVT) of the lower extremity. Ninety-six extremities were studied. In this population, in which the prevalence of acute DVT was 43.8%, plethysmography had a sensitivity of 86.8% and a specificity of 72.0%. The predictive value of abnormal findings at plethysmography was 70.2%, and the predictive value of normal findings at plethysmography was 87.8%. Venous manometry was performed successfully in 89 extremities. A statistically significant difference was shown in the mean intravenous pressure between patients with and without acute DVT. However, there was considerable overlap between the two populations, limiting the predictive value of impedance plethysmography in any given patient.

Adult↗
PubMed1988

Spermatic vein embolization with hot contrast material: fertility results.

Spermatic venography with hot contrast material embolization was undertaken in 81 patients with varicoceles and infertility. Long-term follow-up information was available in 91% of the patients, and there was an overall conception rate of 40.5%. Embolization with hot contrast material was easily performed without special embolization devices and proved to be a safe and effective technique.

Adolescent↗
PubMed1988

Percutaneous aspiration and drainage of abdominal fluid collections after pancreatic transplantation.

Pancreatic transplantation, performed to avert or delay the long-term complications of insulin-dependent diabetes mellitus, is sometimes complicated by the development of intraabdominal fluid collections. We performed 33 sonographically guided and CT-guided percutaneous abdominal aspiration and drainage procedures in 22 transplant patients; 25 procedures were done with the pancreatic graft-in-situ, and eight were done after removal of the transplant. All 11 percutaneous aspirations performed in 10 patients were successful in obtaining microbiologic culture material, and there were no complications. Sixteen percutaneous catheter drainages were performed in 13 patients with the graft-in-situ. Subsequent surgical intervention was avoided after only five (31%) of these drainage procedures. However, further intervention was unnecessary after five (83%) of six percutaneous catheter drainages in five patients who had previously undergone transplant pancreatectomy. No significant short-term or long-term complications were identified. Guided percutaneous aspiration of abdominal fluid collections after pancreatic transplantation is a safe and effective means of obtaining diagnostic material, and guided catheter drainage is definitive treatment in approximately one-third of procedures with the graft-in-situ and in most procedures done after removal of the graft.

Adult↗
PubMed1988

Imaging of vascular complications after hepatic transplantation.

Vascular complications after hepatic transplantation can compromise graft and patient survival. Angiography defines the need for revascularization or retransplantation, but the value of noninvasive imaging in this setting is not clear. To assess the relative merit of noninvasive imaging techniques (sonography, scintigraphy, CT, and MR), we retrospectively reviewed 19 major vascular complications that occurred in 15 of 98 hepatic recipients over a 3 1/2-year period. Portal venous thrombosis was seen in seven patients, donor aortic or hepatic arterial thrombosis in seven, and inferior vena caval thrombosis in five. Sonography provided the initial diagnosis of portal venous thrombosis in three, arterial compromise in five, and caval obstruction in four. CT was the first diagnostic examination to identify portal occlusion in two, donor aortic thrombosis in one, and inferior vena caval thrombosis in one. Scintigraphy and MR imaging provided complementary data. Both sonography and CT are useful in the evaluation of vascular complications that occur after hepatic transplantation; however, neither is sufficiently sensitive to obviate angiographic assessment.

Adolescent↗