Search PubMed⌕ Search

Biomedical subjects

T C McCowan

Publications and source records attributed to T C McCowan.

At least 37 records · Page 2Linked to original sources
PubMed1991

Recurrent intracaval renal cell carcinoma: the role of intravascular ultrasonography.

The presence of extension into the vena cava does not preclude curative resection for extensive renal cell carcinomas. However, preoperative assessment of (1) the proximal extent of the tumor and (2) the degree of adherence within the vena cava is necessary to plan operative strategies. The following report describes the successful use of intravascular ultrasonography in the preoperative evaluation of a patient with recurrent renal cell carcinoma with vena caval extension.

Carcinoma, Renal Cell↗
PubMed1990

Use of external jugular vein as a route for percutaneous inferior vena caval filter placement.

Vena caval filter placement via the right external jugular vein was attempted in 13 cases. Eleven percutaneous vena caval filters of four types were successfully placed in the inferior vena cava. Two of the attempts were unsuccessful. The indications for the external jugular vein approach were obstructive lower-extremity deep venous thrombosis in eight cases and hip or pelvic fractures in three cases; the approach was simply the radiologist's preference in the remaining two cases. There were five minor complications in four patients. None of the complications necessitated operative intervention or changed the clinical course of the patient. The external jugular vein is an excellent alternative route for caval filter placement. The external jugular vein approach does not necessitate surgical cutdown in the operating room for venous access, avoids deep vascular punctures in the neck and groin, and is safe in patients receiving systemic anticoagulation therapy.

Female↗
PubMed1990

Inferior vena caval filter thrombi: evaluation with intravascular US.

A 20-MHz intravascular ultrasound (US) transducer inside a percutaneously inserted catheter was used to evaluate inferior vena caval (IVC) filters for thrombi in vitro and in vivo. Six different IVC filters were studied with intravascular US in a saline-filled model. Each filter had a characteristic, recognizable US pattern. Experimental thrombi as small as 0.5 cm3 were easily detected. Intravascular US was used clinically 25 times to evaluate the IVC in 23 patients with 24 IVC filters. Positive-contrast cavograms were available for comparison in all 25 cases. In 13 cases, no thrombi were identified in the filter or IVC with either intravascular US or cavography; in five of 12 cases with thrombi, intravascular US and cavography demonstrated the thrombi equally well. In six cases, intravascular US was superior to cavography in detection or delineation of thrombus in the IVC or filter. Intravascular US was considered superior to external duplex US in evaluation of caval thrombi in all 21 cases available for comparison. No complications from intravascular US were noted.

Adult↗
PubMed1990

Amplatz vena caval filter: clinical experience in 30 patients.

Amplatz vena caval filters were inserted percutaneously in 30 patients. Radiologic and clinical follow-up was available in 24 patients (cavogram, CT, or sonography in 20 patients, plain abdominal radiographs in two, and lower extremity venograms in two). Clinical follow-up only was available in four patients, and autopsy reports were available in two patients without radiologic follow-up. The filter was inserted without difficulty in 29 (97%) of the patients. Complications after insertion included recurrent pulmonary embolism in two (7%) of 30, caval thrombosis in seven (23%) of 30, ipsilateral lower extremity deep venous thrombosis after placement of the filter in one (3%) of 30, caval penetration in two (10%) of 20, and caval stenosis in one (5%) of 20. No migration of the filter was noted. Our experience suggests that the Amplatz vena caval filter is easy to insert and adequately prevents recurrent pulmonary embolism but is associated with a relatively high rate of caval thrombosis.

Aged↗
PubMed1989

Peripheral laser-assisted balloon angioplasty. Initial multicenter experience in 219 peripheral arteries.

In this multicenter clinical series of peripheral laser-assisted balloon angioplasty with an argon laser-heated, metallic-capped fiberoptic, angiographic and clinical success was achieved in a total of 155 (71%) of 219 attempted lesions. When the anatomy of the lesion was subjectively categorized by the angiographer into those considered possible or impossible to treat by conventional balloon angioplasty, clinical success was achieved in 116 (78%) of 149 lesions considered possible to treat with balloon angioplasty (39 [95%] of 41 stenoses and 77 [71%] of 108 occlusions). More importantly, clinical success was achieved in 39 (56%) of 70 lesions considered impossible to treat by conventional means. The incidence of complications, including vessel perforation (4.1%), with this new technique was equal to that reported for conventional balloon angioplasty, decreased with operator experience, and was less than that reported for argon laser angioplasty with bare fiberoptics. Thus, laser thermal angioplasty with a laser-heated, metallic-capped fiberoptic is a safe procedure that is easily learned by physicians skilled in interventional techniques. It allows for nonsurgical treatment of lesions considered difficult or impossible to treat by conventional balloon angioplasty.

Angioplasty, Balloon↗
PubMed1989

Interventions in pulmonary embolism.

Various interventions are available to assist in the management of patients with pulmonary embolism. Most are reserved for patients who either fail standard systemic anticoagulation therapy or are not candidates for anticoagulant therapy. The most common intervention is placement of a vena caval filter. Several different filter devices are available, most of which may be placed percutaneously. Pulmonary thrombolysis with urokinase or streptokinase may be appropriate in some patients with severe, symptomatic pulmonary embolism. Finally, pulmonary embolectomy by means of either a transvenous catheter or surgical technique may be necessary in cases of refractory cardiovascular collapse.

Humans↗
PubMed1989

Duplex pulsed Doppler US versus intracranial pressure in the neonate: clinical and experimental studies.

This study was conducted to determine if the resistive index (RI) could be used for the examination and follow-up of neonates with increased intracranial pressure. First, in a laboratory model with four mongrel dogs, RI was found to correlate linearly with cerebral perfusion pressure. Second, RI was studied in 57 healthy neonates and 285 neonates with abnormal clinical or head ultrasound findings. Average RI for healthy newborns was 75 +/- 10 and was inversely related to gestational age. RI in newborns with abnormal findings was uniformly elevated, but these values varied considerably and were not statistically different from normal values. Third, the RI was found to decrease significantly after patent ductus arteriosus ligation, tapping of subdural effusions, ventricular tapping (later cerebrospinal fluid shunting led to a further drop in RI), and ventriculoperitoneal shunting. Elevated RI indicates possible intra- or extracranial abnormality affecting cerebral blood flow. Doppler RI is valuable in following up neonates with abnormal or unstable conditions and in assessing the effectiveness of therapies to improve cerebral perfusion.

Animals↗
PubMed1988

Effect of a 1.5 Tesla magnetic field on Greenfield filters in vitro and in dogs.

The authors have tested four Greenfield filters for deflection in a 1.5 Tesla magnetic field and found large variations in the amount of deflection among filters. They also placed two filters in dogs and checked the filter for migration by taking radiographs before and after magnetic resonance imaging (MRI) scans. They found no evidence of migration. They conclude that, while most Greenfield filters respond to a magnetic field, the chance of migration of a filter because of an MRI scan is small. Therefore, MRI scanning of patients with Greenfield filters has little risk.

Animals↗
PubMed1988

Laser thermal angioplasty for the treatment of obstruction of the distal superficial femoral or popliteal arteries.

The success rates and clinical effectiveness of percutaneous laser thermal angioplasty for obstruction of the distal superficial femoral or popliteal arteries were assessed. Laser thermal angioplasty was performed with the first commercially available laser system on 25 atherosclerotic vascular lesions in 20 lower extremities of 18 patients. Fifteen of the lesions were occlusions (average length, 5.6 +/- 3.1 cm), and 10 were high-grade stenoses (average length, 2.6 +/- 1.8 cm). Indication for angioplasty was claudication limiting life-style in 12 extremities and threatened limb loss in eight. All patients were treated with a 1.5- or 2.0-mm metal-capped optical fiber attached to a 14-W argon-ion laser. Balloon angioplasty was performed after laser recanalization in all successful cases. The patients were followed by Doppler ankle/brachial index and clinical evaluation. Laser thermal angioplasty was technically successful (vessel recanalization) in 18 (90%) of 20 of the cases. Fourteen (70%) of 20 extremities were successes by ankle/brachial index follow-up, while 15 (75%) of 20 remained clinically improved after an average follow-up of 7.8 +/- 5.3 months. Laser thermal angioplasty has a technical and clinical success rate that compares favorably with previous reports of balloon angioplasty. With proper patient selection, laser thermal angioplasty can reduce the difficulty of traversing lesions that are amenable to standard balloon angioplasty and increase the number of vascular lesions that can be treated percutaneously but could not be recanalized without the use of laser energy.

Aged↗
PubMed1987

Human percutaneous laser angioplasty. Patient selection criteria and early results.

Percutaneous transluminal laser angioplasty is a new method for treating atherosclerotic disease previously not amenable to routine percutaneous transluminal angioplasty techniques. Our results compared favorably with other clinical trials. Patient selection criteria include lesions in the superficial femoral or popliteal system not capable of being treated with routine percutaneous transluminal angioplasty. We think that these lesions include high-grade stenoses or short segmental occlusions. Heavily calcified vessels and long segment occlusions measuring greater than 12 cm in length are probably not amenable to percutaneous transluminal laser angioplasty. The long-term results of this form of therapy for peripheral vascular disease remain unknown.

Aged↗
PubMed1986

Cystic islet cell tumor of the pancreas.

Presented is the fifth case of a cystic islet cell tumor of the pancreas. The diagnosis is usually made postoperatively but should be considered in a patient with "recurrent pseudocyst" or a history incompatible with pseudocyst in combination with a cystic area in the pancreas. Computed tomography is preferred for diagnosis, and resection is the preferred therapy.

Adenoma, Islet Cell↗
PubMed1986

Angioscopically monitored saphenous vein valvulotomy.

Angioscopy was used during in situ saphenous vein bypass grafting in seven patients. We were able to visualize valve incision, immediately identify and correct incomplete valvulotomy, identify side branches as potential arteriovenous fistulas, and assess distal anastomotic integrity. We encountered no retained valve cusps after angioscopy, as verified by Doppler ultrasound and completion angiography. Angioscopy verified distal anastomotic integrity in all patients with distal vein grafts large enough to accept the angioscope. Angioscopy requires minimal time, is relatively easy to use, serves as an adjunct to Doppler ultrasound and completion angiography, and has future potential as a therapeutic tool.

Aged↗
PubMed1986

Laser angioplasty.

Explore the source record for details and available documents.

Arteriosclerosis↗
PubMed1985

Percutaneous angioscopy. Work in progress.

The cardiovascular applications of flexible fiber-optic technology are imminent because of recent advances in miniaturization. In the work described here, angioscopy, or vascular endoscopy, was performed in the cadaveric aorta and in the systemic and pulmonary circulations of the canine model and selected human patients. Subsequent to our development of percutaneous techniques, clinical trials have ranged from lower-extremity venoscopy to aortic-root arterioscopy. Angioscopy could be clinically useful because of relative or absolute contraindications to iodinated contrast material. The ability to see in color and three dimensions may afford some other advantages to angioscopy over conventional angiography.

Animals↗