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Biomedical subjects

D W Hunter

Publications and source records attributed to D W Hunter.

At least 73 records · Page 4Linked to original sources
PubMed1991

Nitinol gooseneck snare for removal of foreign bodies: experimental study and clinical evaluation.

The authors describe their use of a new right-angle snare made of nickel-titanium (nitinol) cable for retrieval of foreign bodies and iatrogenically placed devices. The snare loop is at right angles to the cable and comes in five sizes (5, 10, 15, 25, and 35 mm); its radiographic visualization is enhanced by gold-plated tungsten coils. This snare was used to retrieve wire and catheter fragments introduced into the thoracic vasculature of four dogs. Eleven of 13 attempts were successful. Three attempts to retrieve intravascular foreign bodies were successful in two patients; in one of these patients, a 10-mm snare was used to remove a fractured end of a ventriculoatrial shunt tube from the left pulmonary artery. In three other patients, four ureteral stents were successfully removed under fluoroscopic guidance. All retrievals were performed through a vascular sheath and with standard techniques and angiographic equipment. No complications were seen in any of the patients or dogs.

Alloys↗
PubMed1991

Pancreatic transplantation: radiologic evaluation of vascular complications.

Transplantation of the pancreas is an increasingly common therapeutic option for preventing or delaying complications of type I diabetes mellitus. The authors studied the relative roles of various radiologic examinations in diagnosing vascular complications in these grafts including arterial and venous thrombosis, stenosis, and anastomotic leak (the most common vascular factors that necessitate pancreatectomy of the transplant), as defined with pathologic or arteriographic data. The results of 78 scintigraphic flow studies, 40 abdominal and pelvic computed tomographic (CT) scans, 27 sonograms, and eight color Doppler studies were evaluated in 52 patients who received a total of 27 cadaveric and 26 living-donor grafts over a 12-year period. These results were correlated with the data from 45 gross and microscopic pathologic studies and 37 arteriograms to determine their relative value in enabling detection of graft thrombosis and other vascular complications. Scintigraphy, CT, sonography, and color Doppler were all sensitive in detection of generalized graft abnormalities but lacked specificity in defining the underlying etiologic factors.

Adult↗
PubMed1991

Clot-trapper device for transjugular thrombectomy from the inferior vena cava.

The clot-trapper device for transjugular thrombectomy was used in 10 dogs with acute thrombosis and two dogs with chronic thrombosis. In eight of these animals, the clots were trapped with the clot-trapper device, then a mechanical thrombectomy device was used to destroy the clots. In 10 animals, including eight with in vitro thrombi and two with in situ thrombi, thrombi were efficiently trapped with the clot-trapper device. In two animals, pulmonary embolism occurred because of a discrepancy between the diameter of the inferior vena cava and the diameter of the bag opening. After increasing the size of the loop to match the diameter of the inferior vena cava, trapping of all thrombi was possible in both experiments (acute and chronic thrombosis). The clot-trapper device, in conjunction with an embolectomy balloon catheter and/or a mechanical thrombectomy device, facilitates the removal of thrombi from the inferior vena cava and iliac veins.

Animals↗
PubMed1991

1990 ARRS Executive Council Award. Intravascular sonography in the detection of arteriosclerosis and evaluation of vascular interventional procedures.

The purpose of this study was to evaluate the use of intravascular sonography for the detection of arteriosclerosis and to determine the effects of vascular interventional procedures on the arterial wall. A catheter-based 20-MHz transducer was used. Forty patients were studied. Twelve had clinical evidence of peripheral vascular disease, 13 were healthy renal donors, and 15 underwent vascular interventional procedures. The aorta and the ipsilateral iliac artery were examined in real time under fluoroscopic guidance and the results were compared with angiography. Sonography in eight of the 13 renal donors showed arterial wall abnormalities in the absence of angiographic evidence of disease. Sonography of the 15 patients after angioplasty or atherectomy demonstrated plaque fractures, intramural dissections, or atherectomy grooves. Our experience suggests that intravascular sonography is of value in reducing the use of angiography to monitor progress or complications of vascular interventional procedures.

Adult↗
PubMed1991

Coronary artery disease in pediatric cardiac transplant recipients receiving triple-drug immunosuppression.

Although triple-drug immunosuppression (cyclosporine, azathioprine, and prednisone) has reduced the incidence of acute rejection after pediatric cardiac transplantation, its effect on the development of coronary artery disease, which may be the major determinant of long-term survival in these patients, is not well defined. We reviewed 42 coronary angiograms obtained annually in 17 cardiac transplant recipients, aged 6 months to 18 years (mean, 12.4 years) at the time of transplantation, who had been maintained on triple-drug immunosuppression and had survived at least 1 year after transplantation. Each angiogram was reviewed for luminal irregularities or discrete stenoses, for the loss of third-order branching, and for the presence of myocardial bridging or calcification of vessels. Patient files were reviewed for donor and recipient age, sex, and ABO blood group, for postoperative episodes of rejection or cytomegalovirus infection, for hypertension, and for cholesterol and triglyceride values. No recipient in our series has died or undergone retransplantation because of coronary artery disease. Six of 17 (35%) patients have developed angiographically identifiable coronary artery abnormalities: four by the first year and two additional recipients by the second and third years, respectively, after transplantation. Development of coronary artery abnormalities approached a significant correlation when related to posttransplantation cytomegalovirus infection (p = 0.11) and older recipient age (p = 0.056) but not to any other factors studied, including episodes of rejection (p = 1.0). Angiographically identifiable coronary artery abnormalities can occur in pediatric recipients within the first year after cardiac transplantation in spite of a low incidence of acute rejection. Although the abnormalities may be mild initially, they can progress and require intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1990

A useful projection for demonstrating the bifurcation of the pulmonary artery.

The demonstration of the pulmonary bifurcation is important in order to exclude pulmonary branch stenoses. The origin of the right and left pulmonary arteries can be demonstrated in the anteroposterior plane if cranial angulation is used. Depending on the course of the left pulmonary artery, the origin of the left pulmonary artery may not be seen in spite of the maximal cranial angulation. On the lateral plane without tube angulation the origin left pulmonary artery is commonly superimposed on the origin of the right pulmonary artery. If maximum caudal angulation is added to the steep left anterior oblique view, not only the left, but also the origin of the right pulmonary artery can be seen.

Constriction, Pathologic↗
PubMed1990

The inferior vena cava clip. The percutaneous approach.

Pulmonary embolism in high-risk patients may be minimized by surgical inferior vena cava (IVC) clipping or by the insertion of caval filters. A percutaneous clipping technique was developed that narrows the cava while allowing caval patency. The caval clip is inserted through a percutaneous translumbar approach under fluoroscopic control. Nine dogs underwent percutaneous translumbar caval clip placement without complications. Three of four dogs, followed-up for 5 to 19 weeks by angiography and caval pressure measurements, showed caval patency. This technique eliminates the risks of surgical IVC clip placement and risks from the insertion of intravascular foreign bodies such as filters.

Angiography↗
PubMed1990

Perineal abscess after prostatic urethroplasty with balloon catheter: report of a case.

A 72-year-old patient underwent uneventful prostatic urethroplasty by means of a balloon catheter. The immediate follow-up retrograde urethrogram failed to demonstrate any areas of extravasation and showed a significant increase in prostatic urethral caliber. Three weeks after the patient was discharged, computed tomography demonstrated a large perineal abscess that was attributed to either the prostatic urethroplasty or subsequent Foley catheter manipulations. The abscess was drained percutaneously, and the patient recovered uneventfully. It was concluded that the abscess was a possible isolated complication and that the procedure is warranted in an adequate clinical setting.

Abscess↗
PubMed1990

Thrombogenicity of hydrophilically coated guide wires and catheters.

The thrombogenicities of stainless steel spring guide wires and two hydrophilically coated guide wires were compared. The guide wires were placed in canine femoral arteries for 30 minutes. The guide wires were removed, the thrombi were stripped off, and the clots were weighed. Clot weights obtained with the two hydrophilically coated guide wires were significantly less than those obtained with the stainless steel spring guide wires. The thrombogenicities of hydrophilically coated catheters and noncoated nylon catheters were compared with and without the use of heparin. Carotid arteries, jugular veins, femoral arteries, and femoral veins were used. Catheters were left in place for 45 minutes. The animals were heparinized and killed. The vessels were then removed en bloc with the catheter clamped in place. The vessels were incised, and the clot was removed and weighed. In arterial and venous catheterization, no significant difference in clot deposition was shown between the hydrophilically coated catheters and the noncoated nylon catheters. A striking reduction of thrombogenicity was achieved with heparinization of the catheters in both arteries and veins.

Angiography↗
PubMed1990

Therapeutic embolization: enhanced radiolabeled monitoring.

Radiolabeling of Ivalon (polyvinyl alcohol sponge) particles permits localization of injected particles during embolization through the use of a portable gamma camera and provides a means to prevent potentially fatal complications such as pulmonary embolization. A more efficient technique of labeling Ivalon particles with technetium-99m sulfur colloid was developed. An increase in labeling efficiency allowed more accurate determination of the distribution of injected Ivalon particles. Scanning electron microscopy demonstrated the stability of the Ivalon particles during this new labeling process. Two patients with arteriovenous malformations underwent therapeutic embolization with radiolabeled Ivalon particles; gamma camera imaging of the lesion and chest was performed throughout the procedure.

Adult↗
PubMed1990

Effect of inosine supplementation on 3-mile treadmill run performance and VO2 peak.

The purpose of this study was to investigate the ergogenic effect of oral inosine (IN) supplementation (6,000 mg.d-1 for 2 d) upon 3-mile run time (3MTIME) and VO2 peak. Nine highly trained endurance runners participated in a double-blind, placebo (PL), crossover study. Each subject undertook an IN or PL trial, consisting of three exercise tests: a submaximal warm-up run (SUBRUN), a competitive 3-mile treadmill run (3MRUN), and a maximal treadmill run (MAXRUN) to determine VO2 peak and time to exhaustion (MAXTIME). Additional measurements during the 3MRUN and MAXRUN included oxygen uptake (VO2), ventilation (VE), respiratory exchange ratio (R), and ratings of perceived exertion (RPE); blood samples were also taken prior (PRERUN) to the SUBRUN test and following the SUBRUN, 3MRUN, and MAXRUN tests in order to assess glucose, pyruvate, lactate, phosphorus, 2,3-DPG, hemoglobin, and uric acid. Analyses of the data revealed no significant effect of oral IN supplementation either upon 3MTIME (IN = 18.31 +/- 1.21; PL = 18.33 +/- 1.15 min) or VO2 peak (IN = 58.6 +/- 5.1; PL = 60.7 +/- 4.5 ml O2.kg-1.min-1) or upon other dependent variables. MAXTIME was significantly longer during the PL trial (P less than 0.05), suggestive of a possible impairment effect of oral IN supplementation. Based upon our data, we conclude that IN is not an effective ergogenic aid to enhance athletic performance of an aerobic nature.

Administration, Oral↗
PubMed1989

Transplant renal artery stenosis: evaluation with duplex sonography.

Determination of the cause of hypertension in renal transplant recipients has required invasive studies such as angiography. Consequently there has been recent interest in noninvasive evaluation. Over a 19-month period, duplex sonography was performed on the renal transplant vasculature in 31 allograft recipients who also underwent correlative arteriography. One patient underwent a repeat duplex study and arteriography after surgical repair. On the basis that a frequency shift greater than 7.5 kHz and associated distal turbulence indicate stenosis, 18 duplex sonographic studies were considered positive. Subsequent angiography showed renal artery stenosis in 16 patients and no significant lesion in two. In 14 patients Doppler studies were interpreted as normal; angiography showed no significant arterial abnormality in 13 and significant stenosis in one. These results indicate a sensitivity of 94.1% and specificity of 86.7% for duplex sonography in the diagnosis of transplant renal artery stenosis. Duplex sonography appears to be an excellent noninvasive screening method to evaluate arterial stenosis following renal transplantation.

Adolescent↗
PubMed1989

Mortalities associated with use of a commercial suspension of polyvinyl alcohol.

Two cases of symptomatic neonatal hepatic arteriovenous malformation (AVM) are presented. Both were treated with percutaneous transcatheter embolization and a commercially available polyvinyl alcohol suspension. Both infants died soon after AVM embolization. The results of laboratory examination of particle-size homogeneity of this commercial suspension demonstrate marked inhomogeneity of particle size very probably contributed to the death of these patients. A protocol has been developed to help determine appropriate particle size in individual cases; this may help prevent such catastrophic results during transcatheter embolization.

Arteriovenous Malformations↗
PubMed1989

Aorta balloon angioplasty: 9-year follow-up.

Nine-year patency and clinical effectiveness of balloon angioplasty of the aorta in a patient with Leriche syndrome are described. The morbidity of surgical intervention for aortoiliac disease is compared with that of percutaneous transluminal angioplasty. These results suggest that aortic balloon angioplasty is a safe and effective procedure with good long-term results.

Angioplasty, Balloon↗
PubMed1989

Biliary complications after liver transplantation in children.

To evaluate the role of interventional radiologic procedures in the diagnosis and treatment of biliary complications in children after liver transplantation, the authors reviewed the cases of 58 pediatric patients who underwent transplantation over a 4-year period. In 21 patients suspected of having biliary complications, 31 diagnostic percutaneous transhepatic cholangiographic studies, 19 transhepatic biliary drainages, eight pressure-flow studies, five percutaneous drainages of abdominal fluid collections, 11 balloon dilations, and one basketing procedure were performed. Biliary complications were seen in 38% of allografts, with obstruction being more common than leakage. Complications were most frequent in patients with cholecystojejunostomy reconstructions. Only two children had biliary complications that were thought to be related to arterial compromise. No significant intervention was required in 17% of complications. Percutaneous techniques were associated with a low frequency of significant complications (6%). The authors conclude that interventional radiologic techniques can be used effectively in the evaluation and management of biliary complications in pediatric hepatic transplant recipients.

Catheterization↗