Biomedical subjects

D W Hunter

Publications and source records attributed to D W Hunter.

At least 37 records · Page 2Linked to original sources

PubMed1997

Sonographic findings in bone marrow transplant patients with symptomatic hepatic venoocclusive disease.

Sonographic findings were retrospectively compared between 19 patients with hepatic venoocclusive disease and 23 patients with other common causes of symptomatic liver dysfunction after bone marrow transplantation (14 grafts versus host disease and nine hepatitis). Doppler sonographic examination was available in all patients with venoocclusive disease, in nine of the patients with graft versus host disease, and in three of the patients with hepatitis. The hepatic artery resistive index and the overall flow direction, peak forward and retrograde velocities, and time-averaged mean velocities in the hepatic veins and main portal vein were compared. The portal vein waveform was arbitrarily considered abnormal in the presence of any of the following: highly pulsatile waveform, very low mean velocity, biphasic flow, or flow reversal. Ascites was the most predictive gray scale sonographic finding for venoocclusive disease. Doppler sonographic findings of potential value in the diagnosis of hepatic venoocclusive disease include an abnormal portal vein waveform, resistive index of greater than 0.75, and marked thickening and edema of the gallbladder wall. However, the study is limited by its retrospective nature and reliance primarily on clinical criteria for the diagnosis of venoocclusive disease. Therefore, our findings will need to be verified in a large prospective study.

Adult↗

PubMed1996

Isolation and description of carbazole-degrading bacteria.

Carbazole is a nitrogen heterocyclic compound associated with fossil fuels and their products. Enrichment cultures were established to isolate bacteria able to degrade carbazole and a plate assay was developed to select carbazole-degrading microorganisms from the enrichments. Three different bacterial isolates capable of mineralizing carbazole were obtained. No intermediates of carbazole degradation were detected. The bacteria had a limited substrate specificity; all used benzoate for growth but were unable to utilize the analogues of carbazole, fluorene, or dibenzothiophene.

Bacteriological Techniques↗

PubMed1996

The mechanisms of positional dysfunction of subclavian venous catheters.

PURPOSE: To determine the origin of subclavian vein catheter and lead dysfunction. MATERIALS AND METHODS: Cineradiography was performed on 10 patients with subclavian venous catheter dysfunction and three patients with pacemaker or defibrillator lead dysfunction. The leads and catheters were removed and replaced with use of a fluoroscopically guided technique; the needle entered the vein lateral to the first rib. Repeat cine examinations were performed following placement of new catheters. RESULTS: The cause of the dysfunction of all 10 catheters was shown to be pinch by the subclavicular musculotendinous tissues as the catheter passed below the clavicle toward its entry into the vein. All three leads were entrapped in the subclavicular tissues and stretched during abduction. The abnormal motion and clinical problems were eliminated after replacement. CONCLUSION: Subclavian catheter and lead malfunction is not due to compression between the first rib and the clavicle. It is due to entrapment in the subclavius muscle-costoclavicular ligament complex, which binds or compresses the device during movements. These problems can be avoided by employing fluoroscopically guided puncture techniques that enter the vein lateral to the first rib.

Catheterization, Central Venous↗

PubMed1996

Iliofemoral venous stenoses: effectiveness of treatment with metallic endovascular stents.

PURPOSE: To assess effectiveness of metallic endovascular stents in treatment of venous stenoses and occlusions. MATERIALS AND METHODS: Stents were placed intravenously in 56 patients (59 stenoses or occlusions) over a 6-year period. Stent sites included the inferior vena cava (n = 10) and common iliac (n = 31), external iliac (n = 46), common femoral (n = 27), and superficial femoral veins (n = 4). Indications for stent placement included stenoses from pelvic malignancy and its treatment; trauma, surgery, or pregnancy; and idiopathic stenoses. Patients underwent anticoagulation therapy for 3-6 months after stent placement. Follow-up was performed with duplex ultrasound. RESULTS: With use of life-table analysis, overall primary and secondary 1-year patency rates were 50% and 81%, respectively. Primary and secondary 4-year patency rates were and 50% and 75%, respectively. Five patients died of primary disease progression within 6 months after stent placement. Major complications occurred in 6.8% of cases. One-year secondary patency rates were statistically significantly lower (P = .05) for patients with malignant disease, although primary patency rates were comparable. Overall sustained decrease in symptoms (P < .0001) was observed 1 year later. CONCLUSION: Endovascular stent placement is a nonsurgical alternative for reestablishment of venous flow and sustained relief of symptoms in patients with malignant or benign pelvic venous disease.

Adult↗

PubMed1996

Effect of transjugular intrahepatic portosystemic shunt on quality of life.

OBJECTIVE: The objective of this study was to determine the effect of the transjugular intrahepatic portosystemic shunt (TIPS) procedure on the quality of life. SUBJECTS AND METHODS: Data were collected on 99 patients who underwent the TIPS procedure between September 1991 and September 1995. Quality of life was assessed by the Karnofsky scale before and at intervals after the procedure. Procedure-related complications and other aspects of the patients' overall well-being, as reflected in liver and kidney function and nutritional status, were reviewed immediately before and after TIPS creation. Finally, mortality and TIPS patency rates were tabulated. RESULTS: We observed significantly improved quality of life. The quality of life remained significantly improved throughout the 24-month follow-up period. During the 1- to 3-month interval after the TIPS procedure, we observed in patients a significant decrease in blood urea nitrogen and an increase in albumin and bilirubin. During this period, patients had no significant change in liver enzymes, prothrombin time, ammonia, or creatinine. Complications of the TIPS procedure included a 30% incidence of new or worsened encephalopathy and a 15% incidence of other severe complications (intraperitoneal hemorrhage, severe accelerated liver failure). The procedure-related death rate was 5%. Longer term follow-up showed an overall sustained decrease in blood urea nitrogen, an increase in albumin, and a return of bilirubin to the pre-TIPS levels or below. CONCLUSION: For patients who survive longer than 1 month, TIPS results in an overall, sustained improvement in the quality of life. Improved quality of life may result from a low incidence of repeat variceal bleeding, decreased ascites, and improved nutritional status.

Adolescent↗

PubMed1996

Placement of an implantable venous access device for use in maintenance ECT.

Achieving intravenous (i.v.) access prior to electroconvulsive therapy (ECT) can be painful and time consuming. It may contribute to premature discontinuation of therapy. The authors report a novel method of ensuring i.v. access in a patient receiving maintenance ECT who developed an aversion to needle sticks. A Port-A-Cath P.A.S. vascular access catheter, placed in her left forearm, has been used for > 30 treatments without complication.

Adult↗

PubMed1995

Management of pelvic venous stenosis with intravascular stainless steel stents.

Patients with gynecologic malignancies may develop stenosis of the large pelvic veins as a result of their disease or its treatment. The percutaneous insertion of a stainless steel vascular stent is a novel approach to the management of an extrinsically compressed vein. The objective of this study was to review the results of treating lower extremity edema secondary to a pelvic venous stenosis through the percutaneous insertion of a stainless steel vascular stent. A retrospective review was performed on gynecologic oncology patients who presented with an edematous lower extremity and underwent an evaluation to diagnose proximal venous stenosis. The evaluation included sonography, venography, and balloon angioplasty prior to the percutaneous insertion of a stainless steel vascular stent. If a venous thrombosis was documented, thrombolysis with urokinase was performed prior to evaluation for venous stenosis. Records were reviewed for the etiology of the venous stenosis, the location and type of stent inserted, and the ability of the stent to maintain patency and provide symptomatic relief. Patency was evaluated at 1-week and then at 1-, 3-, and 6-month intervals. The probability of vascular stent patency was calculated using life table analysis. Ten patients with cervical (n = 4), corpus (n = 3), ovarian (n = 1), vulvar (n = 1), and vaginal (n = 1) cancer had one or more vascular stents inserted for the treatment of a stenosed pelvic vein. The etiologies of venous stenosis were radiation fibrosis and surgery (n = 5), postoperative fibrosis (n = 3), and metastatic tumor (n = 2). The stented vessels were the left common (n = 5) or left external (n = 4) iliac veins, the right common (n = 1) or right external (n = 3) iliac veins, and the right common femoral vein (n = 1). The median follow-up was 21 months. All patients had subjective resolution of their edematous extremity while the stents were patent. The interval probability of patency of stented veins was greater than 85% at each evaluation interval. Patency was 100% for patients beyond 6 months of follow-up. There were no major complications. The percutaneous intravascular insertion of a stainless steel stent was safe and subjectively effective in the management of venous stenosis associated with a gynecologic cancer. A prospective trial with objective endpoints may be warranted.

Adult↗

PubMed1995

Nonsurgical management strategies for the functional complications of ileocolonic continent urinary reservoirs.

Urinary diversion with creation of a continent ileocolonic reservoir was performed in 25 patients with gynecological malignancies at our institution between September 1989 and September 1994. A retrospective review was conducted and cases were analyzed for functional complications associated with reservoir formation. Functional reservoir complications were defined as (1) difficulty with catheterization, (2) reservoir fistulae, (3) reservoir stones, and (4) ureteral stenosis. Management strategies and outcomes for these complications were determined. All patients had received prior pelvic radiation therapy. There was no surgical mortality. Median follow-up was 21 months, and 16 patients (64%) are currently alive. Fourteen of the patients (56%) had one or more complications attributable to a functional aspect of the continent reservoir. Two patients had difficulty with catheterization (8%), two patients had reservoir leak (8%), and one patient had reservoir stones (4%). Nonsurgical management strategies were used in these cases including balloon dilation of the ileocecal valve, stomal dilation, ureteral stenting, percutaneous nephrostomy, and endoscopic lithotripsy. All cases of catheterization problems, reservoir fistulae, and reservoir stones were resolved with nonoperative techniques. Thirteen of 50 ureters (26%) had some degree of stenosis. Percutaneous balloon dilation was utilized in nine cases of ureteral stenosis. Relief of stenosis was complete in five, partial in two, and not achieved in two of the cases. No patients required a reoperation for a reservoir complication. In conclusion, continent ileocolonic urinary diversion can be performed in patients previously treated with radiotherapy; however, functional reservoir problems may occur. Interventional radiology strategies are useful in managing many of these problems and reexploration can be successfully avoided.

Adult↗

PubMed1995

Pacemaker and defibrillator lead entrapment: case studies.

Cadavers and cineradiographic analysis have been used to document the effects of the medial subclavicular musculotendinous complex (MSMC) upon lead function. Four cadavers with pacemakers were dissected and photographed to demonstrate the course a lead takes as it passes through the costoclavicular region. One lead had been placed into the cephalic vein. In the other three cadavers, leads placed by currently accepted techniques of subclavian venipuncture were all found to pass through the soft tissues of the subclavicular region before entering the venous system. Cineradiographic results from a patient with a defibrillator, taken before and after replacement of a broken lead, show the effect of clavicular motion on a lead that passes through the MSMC. Furthermore, cineradiography makes it possible to identify the point where the lead entered the vein, and whether or not it escaped being caught up in the soft tissues of the MSMC.

Cadaver↗

PubMed1995

Applications of the Amplatz snare device during interventional radiologic procedures.

The Amplatz gooseneck snare (Microvena, St. Paul, MN) is a recently developed device for the percutaneous removal of intravascular foreign bodies [1-5] (Fig. 1). In the past several years, various other applications of this snare system have been devised for placing, replacing, repositioning, or removing guidewires, catheters, and other devices during interventional procedures. The Amplatz gooseneck snare, which has been described [1], comes in a variety of loop sizes and is provided with either 4- or 6-French guiding catheters, although substitution with any of several soft, blunt-tipped guiding catheters is possible [5]. The principal advantage of the Amplatz snare over past systems is that the loop is at a right angle to the catheter, easing the capture of foreign bodies, devices, or catheters.

Blood Vessels↗

PubMed1994

Resting Tl-201 scintigraphy in the evaluation of coronary artery disease in children with Hurler syndrome.

Severe coronary artery disease may occur early in the course of mucopolysaccharidosis. The authors present radiologic, scintigraphic, and pathologic findings in five patients with Hurler syndrome. Thallium-201 myocardial scintigraphy and selective coronary angiography obtained within 2 days to 6 months were correlated in five patients. Postmortem examination of the coronary arteries was obtained in one patient within hours of angiography. Interobserver agreement on grading of scintigraphic abnormalities was poor. Nonspecific findings on Tl-201 studies included septal abnormalities in all five patients. Scintigraphic findings were corroborated by angiography and postmortem results in only 3 of 5 patients. Our findings suggest that resting Tl-201 scintigraphy has limited value in the detection of coronary artery disease in patients with Hurler syndrome.

Child, Preschool↗

PubMed1994

Alternative design for radiologic guidance in video thoracoscopic surgery.

RATIONALE AND OBJECTIVES: Easy dislodgment and a pneumothorax rate of up to 50% have been reported with the use of mammographic hookwires for radiologic guidance in thoracoscopic surgery. An alternative design is described and preliminary in vitro results are reported. METHODS: The new design is based on the T-fastener used in percutaneous gastrostomies and can be deposited with a 20-Fr guidance needle. In vitro measurements of the anchoring capability of this design were compared with the anchoring capability of the Hawkin's III (Meditech/Boston Scientific, Watertown, MA) mammographic hook wire system. RESULTS: Anchoring capabilities of the alternative anchoring design and the Hawkin's III mammographic hook wire localization system are comparable. Complete dislodgement of both anchors occurs at approximately 350 gm. CONCLUSIONS: Preliminary in vitro investigation demonstrated similar anchoring capabilities of the new design and mammographic hook wires. Potential advantages of this suture-based localization device over hook wires are discussed.

Equipment Design↗

PubMed1994

In vitro metal fatigue testing of inferior vena cava filters.

RATIONALE AND OBJECTIVES: Inferior vena cava filter fractures have been described in vivo on several occasions. No studies have compared the fatigue life of the different filter types. Four different, frequently used filters (Vena-Tech filters [VTF], stainless-steel Greenfield filters [SSGF], Simon nitinol filters [SNF], and titanium Greenfield filters [TGF]) were, therefore, tested with regard to fatigue life. METHODS: Ten filters of each type were tested by compressing the filter legs repeatedly. A travel distance of 1.5 cm was used, setting minimal and maximal filter leg separations of 1.0 cm and 2.5 cm, respectively. The endpoint was filter fracture or 10,000,000 compressions. The test was then repeated on five of the filters from each group, but on a different filter leg pair. RESULTS: Seven of 10 VTFs fractured during the first part of the study, and all five VTFs fractured during the second part of the study. One SSGF fractured in each part of the study. None of the SNFs or the TGFs fractured. Significant difference in fracture frequency was found. CONCLUSION: The VTFs appear to have the shortest fatigue life. The TGF and the SNF have a fatigue life exceeding the test limits. The consequences of filter fracture are unknown.

Alloys↗

PubMed1994

Development of stenoses in transjugular intrahepatic portosystemic shunts.

PURPOSE: To evaluate the frequency and significance of stenoses or occlusions developing within transjugular intrahepatic portosystemic shunts (TIPS) and identify predictive factors. MATERIALS AND METHODS: Medical records of 52 patients who underwent TIPS placement between September 1991 and October 1993 were reviewed. Various shunt parameters were correlated with the development of shunt abnormalities. Findings at follow-up portography and frequency of variceal bleeding and paracentesis were also noted. RESULTS: Twenty-four patients were followed up for at least 6 months. In eight patients, stenoses developed within 6 months; one shunt occluded. No clear correlations were found between shunt parameters and development of shunt abnormalities. Two of four patients with recurrent variceal bleeding had associated shunt abnormalities. The frequency of stenosis of TIPS was high. CONCLUSION: Early detection and prompt revision of stenotic shunts may decrease the frequency of recurrent variceal bleeding and ascites.

Adolescent↗

PubMed1994

Relative effects of alpha 1-adrenoceptor blockade, converting enzyme inhibitor therapy, and angiotensin II subtype 1 receptor blockade on ventricular remodeling in the dog.

BACKGROUND: Progressive ventricular remodeling after myocardial damage is associated with a poor prognosis. Optimal prevention of the histopathological processes involved in remodeling requires a more complete understanding of the mechanisms involved in initiating and maintaining these structural changes. Since the sympathetic nervous system and the renin-angiotensin system may be involved in the remodeling process, the structural effects of pharmacological inhibitors have been evaluated in a canine model of localized myocardial injury resulting from transmyocardial DC shock. METHODS AND RESULTS: The study is comprised of two protocols run in series. In protocol 1, zofenopril (Z), a converting enzyme inhibitor (CEI), prevented the increase in left ventricular mass (LVM) and end-diastolic volume (LVV) observed in the control group (C) at 16 weeks (Z: LVM, 69.8 +/- 3.4 to 65.4 +/- 2.6 g, P = NS; LVV, 45.4 +/- 2.7 to 51.6 +/- 2.7 mL, P = NS; C: LVM, 68.4 +/- 3.2 to 91.4 +/- 2.9 g, P = .0001; LVV, 56.6 +/- 3.0 to 71.9 +/- 2.4 mL, P = .0003). Terazosin, an alpha 1-adrenoceptor antagonist, failed to prevent remodeling at 16 weeks despite continued receptor blockade. In protocol 2, the antiremodeling effect of full-dose CEI therapy with ramipril was confirmed. Low-dose ramipril that exerted no hemodynamic effect failed to prevent remodeling (LVM, 89.7 +/- 4.6 to 105.7 +/- 3.4 g, P = .01; LVV, 61.8 +/- 3.8 to 76.8 +/- 3.3 mL, P = .002). An angiotensin II subtype 1 receptor blocker also failed to prevent the increase in LVM or LVV (LVM, 89.0 +/- 4.6 to 109.7 +/- 5.3 g, P = .0001; LVV, 66.0 +/- 1.9 to 78.4 +/- 3.6 mL, P = .007). CONCLUSIONS: High-dose CEI therapy can prevent progressive structural changes resulting from localized myocardial damage induced by DC shock. the failure of alpha 1-adrenoceptor blockade and angiotensin II subtype 1 blockade to attenuate remodeling argues against an important direct role for norepinephrine acting through alpha 1-receptors or angiotensin II acting through the type 1 receptor in the remodeling process in this model.

Adrenergic alpha-Antagonists↗

PubMed1993

Transcatheter closure of congenital coronary arterial fistula with a detachable balloon.

Coronary arterial fistulae are rare congenital cardiac defects that typically are treated by surgery. A case of transcatheter closure of a left anterior descending coronary artery to right ventricular fistula with a detachable balloon is described in a 16-month-old child. The fistula was easily occluded without complication. Follow-up 1.5 years later revealed normal ventricular function and no recurrence of the fistula. Detachable balloon occlusion of coronary arterial fistula is feasible in patients as young as 4 months.

Cardiac Catheterization↗

PubMed1993

Evaluation of a new vascular occlusion device.

RATIONALE AND OBJECTIVES: A new vascular occlusion device was tested in canine femoral and iliac arteries and in an animal model of a patent ductus arteriosus (PDA). METHODS: Four variations of the vascular plug were placed into 18 iliac or femoral arteries of 17 mongrel dogs. Follow-up angiography was performed 1 hour and, if necessary, 2 hours after placement in all animals, 14 of which were then killed. Three dogs were followed angiographically for 2 weeks to 3 months. The "butterfly" plug was then tested in a canine model of a PDA. RESULTS: All plugs contained thrombi, and 12 of the 18 devices caused complete or nearly complete vascular occlusion within 2 hours. In one dog, one vascular plug had eroded through the vessel wall at 3 months without clinical sequelae. Successful PDA occlusion was achieved in 1 or 2 days in 6 of 8 dogs. Three misplacements occurred, one of which resulted in death. DISCUSSION: The balloon-expandable vascular plug appears to be a promising device for occlusion of blood vessels. Migration has not been observed once the device is placed, thus, sizing of the device appears less critical than with coils. However, modification of the delivery system and considerably more experience with the device are necessary to reduce the risk of misplacement.

Animals↗

PubMed1993

A new approach to percutaneous subclavian venipuncture to avoid lead fracture or central venous catheter occlusion.

Pacemaker and defibrillator leads and central venous catheters placed by commonly recommended techniques have been found to pass through the subclavius muscle, the costocoracoid ligament, or the costoclavicular ligament before entering veins medial to the first rib. Entrapment by these soft tissues subjects leads and catheters to stresses imposed by movements of the ipsilateral upper extremity. Accordingly, a new approach has been developed that introduces the lead or catheter into the subclavian vein near the lateral border of the first rib. This placement avoids soft tissue entrapment and may extend the longevity of leads and catheters.

Bloodletting↗