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Biomedical subjects

R I White

Publications and source records attributed to R I White.

At least 73 records · Page 4Linked to original sources
PubMed1987

Mesoatrial shunts for Budd-Chiari syndrome and inferior vena cava thrombosis: angiographic and hemodynamic evaluations.

When inferior vena caval obstruction complicates the Budd-Chiari syndrome, conventional portosystemic shunts are not possible. The mesoatrial shunt has been devised to enable portal and sinusoidal decompression in these patients. Findings in 12 patients with Budd-Chiari syndrome and inferior vena caval obstruction in whom a mesoatrial shunt was performed are reported. Preoperative inferior vena cavography with pressure measurements is essential to determine the appropriate shunt procedure. Postoperatively, shunt patency is assessed with superior mesenteric arterial portography. Where possible, transvenous catheterization of the shunt is performed to confirm patency and assess hemodynamic function.

Adult↗
PubMed1987

Outpatient embolotherapy of varicocele.

A detectable balloon technique for precise embolotherapy of varicocele has been developed. Results in 334 patients whose internal spermatic veins were occluded between 1979 and 1985 indicate satisfactory restoration of fertility with minimal morbidity and cost.

Ambulatory Care↗
PubMed1986

Upper-extremity venography using digital subtraction angiography.

Venography to evaluate the patency of upper-extremity veins was performed with digital subtraction angiography (DSA) and conventional angiography. Venous thrombosis was easily diagnosed, and the innominate veins and superior vena cava were more easily visualized using DSA. Iodine concentration for DSA was one-third that of conventional venography, and the examination time was reduced by 50% using DSA. Patient comfort and acceptance were greater with DSA. DSA is a superior technique for upper-extremity vein evaluation in cooperative patients.

Adult↗
PubMed1986

Interventional procedures in congenital heart disease.

Balloon septostomy changed the natural history of transposition of the great arteries. Relatively little more occurred in catheter treatment of congenital heart disease until the development of the balloon catheter for transluminal angioplasty. Modification of these catheters led to successful treatment of valvular pulmonic stenosis, peripheral pulmonic stenosis, and coarctation restenosis. Possible future applications of balloon valvuloplasty include valvar aortic stenosis, stenotic shunts, and palliative operations. Pulmonary arteriovenous malformations are well managed by detachable balloon techniques, and balloons and coils are used for occluding large systemic collaterals. Interventional techniques have made a significant impact on the treatment of congenital heart disease, and it is anticipated that as technology improves further advances will occur.

Adult↗
PubMed1986

Comparison of recurrent varicocele anatomy following surgery and percutaneous balloon occlusion.

Venography of 44 recurrent varicoceles in 37 patients demonstrated different anatomical patterns of recurrence in surgical patients (26) compared to those treated by percutaneous balloon occlusion (18). The 3 types of patterns identified included parallel, renal vein and transcrotal collateral pathways. Virtually all surgical recurrences were owing to mid retroperitoneal (27 per cent) or low (inguinal) parallel collaterals (58 per cent). The majority of post-balloon occlusion recurrences were due to either high retroperitoneal parallel (44 per cent) or renal vein collaterals (28 per cent). Surgical recurrences were treated easily with percutaneous balloon occlusion. However, 39 per cent of the patients with recurrences following balloon embolization were not anatomical candidates for repeat percutaneous occlusion. We conclude that venous collaterals are identified easily by renal venography, and knowledge of these collaterals is helpful in planning further surgical or radiological treatment.

Embolization, Therapeutic↗
PubMed1986

Measurement of peripheral blood flow by thermodilution techniques.

Recent advances in the diagnosis and treatment of cardiovascular pathology, including balloon angioplasty of atherosclerotic lesions in peripheral vascular disease, have led to an increased need for in vivo quantitation of blood flow. This study has three purposes: (1) to validate thermodilution techniques as a viable method for measuring low blood flow rates, (2) to calibrate accurately thermodilution catheters at these low flows, and (3) to develop an animal model that can be used to quantitate and compare many different flow measuring techniques. Modified commercially available 6F thermodilution catheters were used with a standard cardiac output computer to measure flows between 200 and 700 ml/minute. Eight anesthetized dogs were surgically interfaced with a variable flow, pressure, and compliance carotid-carotid/jugular bypass perfusion system. Three milliliters of normal saline at room temperature were injected through the catheters intra-arterially to measure different flows below, at, and above physiologic pressures and compliances. Results of this study indicate that with proper calibration, thermodilution techniques of measuring arterial and venous flows between 200 and 700 ml/minute are simple, accurate, and reliable. Using the designed system to generate known flows in vivo at various physiologic conditions allowed easy calibration of catheters and should facilitate calibration and comparison of other measurement techniques.

Animals↗
PubMed1986

Right-sided varicocele: technique and clinical results of balloon embolotherapy from the femoral approach.

Among 227 patients undergoing outpatient balloon embolotherapy for varicocele, venography of the right internal spermatic vein (ISV) was attempted in 48. A percutaneous technique from the right femoral vein was used for all patients. The right ISV was successfully occluded with detachable balloons in 41 of 46 (89%), while in five (11%), the right ISV could not be embolized. A competent valve was found in two patients. The right ISV alone was embolized in ten patients: one had a solitary right varicocele, six had left varicoceles but competent valves in the left ISV, and three had recurrent left varicoceles after successful left ISV occlusion. Bilateral ISV embolization was achieved in 31 patients. Long-term follow-up study was available for 25 patients; 12 couples (48%) achieved a pregnancy. Percutaneous balloon occlusion of right varicoceles is a safe, effective outpatient technique.

Angioplasty, Balloon↗
PubMed1986

Liquid gold: low-osmolality contrast media.

The use of low-osmolality versus high-osmolality contrast media is debated. The authors conclude that more studies need to be performed before the high cost of low-osmolality contrast media can justifiably be passed on to the patient population.

Clinical Trials as Topic↗
PubMed1986

In situ saphenous vein bypass grafts: angiographic evaluation and interventional repair of complications.

In situ saphenous vein grafts are being used with increasing frequency for bypass procedures involving the femoral and popliteal arteries. Complications of these procedures include anastomotic stenoses and persistent arteriovenous fistulae that may result in failure of the graft. Balloon angioplasty and embolotherapy with detachable balloons were employed successfully in three or four recent cases of patients with complications from in situ grafts. Tailored angiography is essential for evaluating in situ grafts, and interventional techniques are extremely useful for managing complications.

Aged↗
PubMed1986

Vessel sizing wire: accurate vessel measurement using digital subtraction arteriography.

A simple method of measuring vessel diameters using intraarterial digital subtraction angiography has been designed. With a catheter in place within the vessel of interest, a segmented guide wire with known dimensions is advanced into the catheter in the area to be measured. We have used the method successfully for balloon angioplasty as well as balloon embolization.

Angiography↗
PubMed1986

Percutaneous spermatic vein occlusion: evaluation of sclerosing agents in experimental animals.

The 5%-20% rate of recurrence of testicular varicoceles after embolotherapy has been a persistent clinical problem. Three sclerosing agents--sodium tetradecyl sulfate 3%, absolute ethanol, and 100 degrees C contrast material--were evaluated in canine spermatic veins for degree and durability of venous occlusion. Pathologic examination for perivenous, pulmonary, and neural changes was performed. Both sodium tetradecyl sulfate and absolute ethanol were effective sclerosants, but sodium tetradecyl sulfate was technically easier to use. The use of a sclerosant in conjunction with balloons or coils is the safest, most effective technique for occluding variococeles and minimizing postembolotherapy recurrences.

Animals↗
PubMed1986

Long-term results of superficial femoral artery angioplasty.

Short-term results of superficial femoral artery and popliteal percutaneous transluminal angioplasty have been good, but long-term results and factors influencing long-term patency are less commonly reported. One hundred thirty-seven superficial femoral artery angioplasties with follow-up for 54 months were reviewed. The 4-year patency for stenoses was 61% and for occlusions was 68%. If the initial result was clinically successful, the 4-year patency was not influenced by the quality or patency of runoff or by the length of the occlusion. Nineteen patients returned for redilatation, eight of whom had developed new lesions. Patency was adversely affected in patients with diabetes or with long-segment stenoses. Modifications of equipment and technique that may improve long-term patency rates are discussed.

Angioplasty, Balloon↗
PubMed1985

Cerebral embolism--first manifestation of pulmonary arteriovenous malformation in patients with hereditary hemorrhagic telangiectasia.

Four of five patients with asymptomatic small or moderate-size pulmonary arteriovenous malformation (PAVM) presented with a paradoxical embolus and stroke. In these patients chest radiographic findings were subtle and arterial hypoxemia provided the real clue to diagnosis. Computed tomography (CT) and cerebral arteriography confirmed embolic occlusion in four of five patients. Careful family screening including posteroanterior (PA) and lateral chest radiographs and arterial oxygen determinations in sitting or standing positions are recommended for early detection of asymptomatic patients with PAVM. Early therapeutic intervention (with balloon embolotherapy) is recommended to avoid paradoxical embolization.

Adult↗
PubMed1985

Late false aneurysm following replacement of ascending aorta: the problem of the teflon graft in combination with a silk suture anastomosis.

Two patients underwent resection and replacement of the ascending aorta using a low-porosity Teflon graft anastomosed with silk suture. In both patients false aneurysms developed that required operation 13 and 23 years postoperatively. The clinical courses of these patients, along with data from the literature, suggest that the combination of a low-porosity Teflon graft and a silk suture anastomosis presents a major potential hazard for the development of anastomotic false aneurysm.

Adult↗
PubMed1985

Low-dose thrombolytic therapy for infrainguinal graft occlusions: an idea whose time has passed?

Despite the growing enthusiasm for low-dose intra-arterial thrombolytic therapy, the efficacy and risks in specific clinical situations have not been defined. During the past 13 months, 10 infrainguinal bypass graft occlusions occurred in nine patients 2 to 48 months postoperatively and were treated with local infusions of either streptokinase or urokinase. The grafts treated included two saphenous vein femoropopliteal grafts, two expanded polytetrafluoroethylene (PTFE) femoropopliteal grafts, four saphenous vein femoro-anterior tibial grafts, one saphenous vein-PTFE composite femoro-anterior tibial graft, and one saphenous vein-PTFE composite femoroperoneal graft. The graft occlusions occurred 2 to 14 days prior to initiation of treatment. The infusion failed to restore flow completely in seven grafts; and of the three successes, two patients required surgical treatment of complications. All successful recanalizations occurred within 48 hours of the initiation of thrombolytic therapy. Of the seven failures, two patients had viable limbs and were discharged, whereas two required amputation (one above and one below knee). Three patients underwent surgical thrombectomy and revisions that were successful in two and resulted in a below-knee amputation in the other. Despite all precautions, complications occurred in five patients. Low-dose intra-arterial thrombolytic therapy is a poorly efficacious, risky method of infrainguinal graft occlusion management.

Adult↗
PubMed1985

Inpatient admissions for interventional radiology: philosophy of patient management.

As an alternative to performing interventional radiology on inpatients under the care of internists and surgeons, the authors have established a cardiovascular radiology admitting service for well-screened, elective patients. The patients are admitted under the care of a cardiovascular radiology fellow and a staff physician. From April 1982 to December 1983, 133 patients were admitted to the service. Patients are cared for in a surgical ward or in an intermediate unit, as determined by the clinical situation. Advantages of this approach include a broader patient referral base, improved rapport with clinical colleagues and patients, improved follow-up data, and rapid evaluation and treatment, resulting in short hospital stays. The major disadvantages involve the commitment of time and staff necessary to provide quality care. The concept of the interventional radiologist in the role of admitting physician has important implications in terms of negotiations for additional financial compensation, commensurate with the skill and time required for performing these procedures and caring for the patient.

Angioplasty, Balloon↗