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Biomedical subjects

K W Sniderman

Publications and source records attributed to K W Sniderman.

At least 19 recordsLinked to original sources
PubMed2003

Portopulmonary hypertension in decompensated cirrhosis with refractory ascites.

BACKGROUND: The prevalence of portopulmonary hypertension (PPHTN) in patients with cirrhosis and refractory ascites is unknown. Its presence may preclude patients from receiving a transjugular intrahepatic portosystemic shunt or liver transplantation as a definitive treatment for their end stage cirrhosis. PURPOSE: To determine the prevalence, possible aetiological factors, and predictive factors for the development of PPHTN in these patients. METHODS: Sixty two patients (53 males, nine females; mean age 54.5 (1.4) years) with biopsy proven cirrhosis and refractory ascites underwent angiographic measurements of pulmonary and splanchnic haemodynamics. Endothelin 1 levels were measured from the pulmonary artery. Forty nine patients underwent radionuclide angiography for measurements of central blood volume, pulmonary vascular, and cardiac chamber volumes. Forty seven patients also underwent two dimensional echocardiography for measurements of cardiac structural and functional parameters. Cardiac output, and systemic and pulmonary vascular resistance were calculated. RESULTS: Ten patients (16.1%) fulfilled the criteria for PPHTN (mean pulmonary artery pressure >/= 25 mm Hg and pulmonary vascular resistance >/= 120 dynxs/cm(5)), with significantly higher mean right atrial (15.4 (1.2) v 7.9 (0.5) mm Hg; p<0.001), and right ventricular pressures (24.7 (1.5) v 14.7 (0.6) mm Hg; p<0.001), and endothelin 1 levels (3.04 (0.40) v 1.98 (0.12) pg/ml; p=0.02). No significant differences in any of the other parameters measured were detected between the two groups. A right atrial pressure of >/= 14 mm Hg had a 83% positive predictive value for the presence of PPHTN. CONCLUSIONS: Portopulmonary hypertension is common in cirrhosis with refractory ascites, possibly due to excess endothelin 1 in the pulmonary circulation. An elevated right atrial pressure >/= 14 mm Hg predicts the presence of PPHTN, which may be helpful in deciding management options in these patients.

Ascites↗
PubMed2001

Subcutaneous heparin versus low-molecular-weight heparin as thromboprophylaxis in patients undergoing colorectal surgery: results of the canadian colorectal DVT prophylaxis trial: a randomized, double-blind trial.

OBJECTIVE: To compare the effectiveness and safety of low-dose unfractionated heparin and a low-molecular-weight heparin as prophylaxis against venous thromboembolism after colorectal surgery. METHODS: In a multicenter, double-blind trial, patients undergoing resection of part or all of the colon or rectum were randomized to receive, by subcutaneous injection, either calcium heparin 5,000 units every 8 hours or enoxaparin 40 mg once daily (plus two additional saline injections). Deep vein thrombosis was assessed by routine bilateral contrast venography performed between postoperative day 5 and 9, or earlier if clinically suspected. RESULTS: Nine hundred thirty-six randomized patients completed the protocol and had an adequate outcome assessment. The venous thromboembolism rates were the same in both groups. There were no deaths from pulmonary embolism or bleeding complications. Although the proportion of all bleeding events in the enoxaparin group was significantly greater than in the low-dose heparin group, the rates of major bleeding and reoperation for bleeding were not significantly different. CONCLUSIONS: Both heparin 5,000 units subcutaneously every 8 hours and enoxaparin 40 mg subcutaneously once daily provide highly effective and safe prophylaxis for patients undergoing colorectal surgery. However, given the current differences in cost, prophylaxis with low-dose heparin remains the preferred method at present.

Anticoagulants↗
PubMed2000

Long-term follow-up of management of failing in situ saphenous vein bypass grafts using endovascular intervention techniques.

PURPOSE: To report the long-term follow-up of previously reported cases of salvaging failing or failed in situ bypass grafts using endovascular techniques, to include previously unreported cases, and to include the results of thrombolysis for the salvage of occluded in situ venous bypass grafts. MATERIALS AND METHODS: Between 1985 and 1995, 352 patients underwent distal bypass via the in situ saphenous vein. Seventy-three of these patients underwent endovascular interventions for (i) graft stenoses (65 lesions in 40 patients) treated by balloon angioplasty (PTA), (ii) AV residual fistulas to veins (AVF) (23 patients) occluded by coil embolotherapy, (iii) graft occlusion (21 occluded grafts in 19 patients) treated by catheter-directed high-dose thrombolytic infusion and PTA or surgical revision of uncovered stenoses, and (iv) retained valve leaflets causing stenoses (five patients) treated by valvectomy and/or PTA. Cumulative patency rates were determined by the Kaplan-Meier method. Twenty-nine of 73 patients had been previously reported by the authors. RESULTS: PTA was successful in 39 of 40 patients, cumulative patency after bypass PTA was 0.79 (SE +/- 0.07) for 12 months and 0.63 (SE +/- 0.12) for 5 years. The only complication of PTA was a graft anastomotic disruption that was successfully treated by surgery. Longer lesions and lesions requiring repeated PTA were more likely to restenose. For thrombolysis, there were 13 of 19 successful infusions and five delayed occlusions. The cumulative patency for both 12 months and 5 years was 0.43 (SE +/- 0.12). AVF embolization was successful in 21 of 23 patients. Cumulative patency for 12 months and 5 years was 0.87 (SE +/- 0.07) and 0.81 (SE +/- 0.09), respectively. Five successful valvectomy procedures were performed by stripping residual valves with endocardial forceps. CONCLUSION: In experienced hands, PTA and AVF embolization can be performed on failing in situ saphenous vein bypass grafts with good long-term patency. Thrombolysis results were less favorable but can prolong patency of grafts.

Aged↗
PubMed2000

Inferior vena cava filters--percutaneous insertion?

The incidence of deep venous thrombosis (DVT) and pulmonary embolism (PE) among Chinese is much lower than in Caucasians. The total number of inferior vena cava (IVC) filters inserted in regional hospitals in Canada (about 700 beds in Toronto General Hospital) and Hong Kong (about 1,250 beds in Pamela Youde Nethersole Eastern Hospital) also reflects this. Thirty-six IVC filters were deployed in Toronto General Hospital, compared to 8 IVC filters inserted in Pamela Youde Nethersole Eastern Hospital from August 1997 to September 1998. Despite this, the physician may encounter patients with thromboembolic disease who require inferior vena cava interruption. The usual indication will be pulmonary embolism with contraindications to, or failure or complications of, anticoagulation therapy. It is important for angiographers to be familiar with the technique of percutaneous insertion of IVC filters. The types of IVC filters, techniques of insertion and guidelines relating to the choice of a filter would be discussed.

Humans↗
PubMed2000

Treatment of nonresectable hepatocellular carcinoma with intrahepatic 90Y-microspheres.

UNLABELLED: Treatment for nonresectable hepatocellular carcinoma (HCC) is palliative. The relatively greater arteriolar density of hepatic tumors compared with normal liver suggests that intrahepatic arterial administration of 90Y-microspheres can be selectively deposited in tumor nodules and results in significantly greater radiation exposure to the tumor than external irradiation. The purpose of this study was to determine the proportion (frequency) and duration of response, survival, and toxicity after intrahepatic arterial injection of 90Y-microspheres in patients with HCC. METHODS: Patients with documented HCC, Eastern Cooperative Oncology Group performance status 0-3, adequate bone marrow, and hepatic and pulmonary function were eligible for study. Patients who had significant shunting of blood to the lungs or gastrointestinal (GI) tract or who could not undergo cannulation of the hepatic artery were excluded. Patients received a planned dose of 100 Gy through a catheter placed into the hepatic artery. RESULTS: Twenty-two patients were treated with 90Y-microspheres; 20 of the treated patients (median age, 62.5 y) were evaluated for treatment efficacy. Nine patients were Okuda stage I, and 11 were Okuda stage II. The median dose delivered was 104 Gy (range, 46-145 Gy). All 22 treated patients experienced at least 1 adverse event. Of the 31 (15%) serious adverse events, the most common were elevations in liver enzymes and bilirubin and upper GI ulceration. The response rate was 20%. The median duration of response was 127 wk; the median survival was 54 wk. Multivariable analysis suggested that a dose >104 Gy (P = 0.06), tumor-to-liver activity uptake ratio >2 (P = 0.06), and Okuda stage I (P = 0.07) were associated with longer survival. CONCLUSION: Significantly higher doses of radiation can be delivered to a HCC tumor by intrahepatic arterial administration of 90Y-microspheres than by external beam radiation. This treatment appears to be beneficial in nonresectable HCC with acceptable toxicity.

Brachytherapy↗
PubMed1999

A practical approach to vascular access for hemodialysis and predictors of success.

PURPOSE: The long-term results and predictors of success for vascular access at The Toronto Hospital were studied. This report describes the access program and emphasizes the role of the vascular access coordinator. METHODS: A total of 384 consecutive patients underwent 466 vascular access procedures. The access program is centered around a dedicated, full-time vascular access coordinator, who is a registered nurse and is responsible for all aspects of access care, including follow-up. Outcome variables were collected prospectively. Primary, primary-assisted, and secondary success was determined by means of Kaplan-Meier analysis, and the stepwise Cox proportional hazards model was used for multivariate analysis of the factors that were independently predictive of primary success. RESULTS: There were 235 autogenous arteriovenous fistulae (AVFs) and 231 arteriovenous grafts (AVGs). The cumulative primary, assisted-primary, and secondary success (patent and functional for effective dialysis) at 24 months for all 466 cases combined was 36% +/- 3%, 54% +/- 3%, and 66% +/- 3%, respectively. The primary success for AVFs and AVGs at 2 years was 54% +/- 4% and 18% +/- 4%, respectively (P <.001; log-rank test); the primary-assisted success for AVFs and AVGs at 2 years was 62% +/- 4% and 44% +/- 6%, respectively (P <.001; log-rank test); and the secondary success for AVFs and AVGs at 2 years was 70% +/- 4% and 60% +/- 5%, respectively (P =.331; log-rank test). Stratification of variables revealed significant benefit for AVFs (P =.001), the female sex (P =.014), and the absence of diabetes mellitus (P =.001). Multivariate analysis with Cox regression determined that access type (AVF vs AVG; P =.001) and diabetes mellitus (P =.024) were independently predictive of primary success. The improved clinical coordination of access patients with the initiation of the vascular access program resulted in a significant reduction in length of hospital stay before and after the program was organized (2.5 +/- 0.06 vs 1.1 +/- 0.03 days; P =.001). CONCLUSION: The organization of a vascular access program in a practical and cost-effective way for reduced length of hospital stay is streamlined through a dedicated access coordinator, who ensures an integrated, multidisciplinary approach. The results for the Cox model is useful when discussing the anticipated results of access procedures with individual patients.

Algorithms↗
PubMed1998

Management of upper extremity central venous obstruction using interventional radiology.

Upper extremity central vein stenosis/occlusion is responsible for significant morbidity. The objective of this report is to review our management using interventional radiological techniques and to determine the long-term clinical results. All radiological interventions for central vein stenosis/occlusion (n = 59) between July 1991 and July 1996 at our institution were reviewed. The interventions consisted of thrombolytic therapy alone in 10 cases, PTA in 40 cases (combined with initial thrombolytic therapy in 6 cases), and deployment of a venous stent in 9 cases. At follow-up, the cumulative success (patency and relief of symptoms) was determined (Kaplan-Meier method). The involved vein was the subclavian, axillary, or innominate (SUB-AX-INN) in 45 cases and the superior vena cava (SVC) in 14 cases. The etiology was secondary to an indwelling foreign body (catheter, pacemaker lead) in 53 cases (90%), and spontaneous in only 6 cases (10%). The average follow-up after intervention was 17.2 months, with a cumulative success of 70 +/- 7.5% at 2 years, with rapid decline thereafter. Analysis of the failure quantiles revealed that 25% failed by 17 months, 50% failed by 26.6 months, and 75% failed by 33.8 months. There were no subgroup differences (log-rank test) for stenosis versus occlusion (p = 0.526), SUB-AX-INN versus SVC (p = 0.744), or if the intervention was begun < 5 days versus > or =5 days after symptom onset (p = 0.240), or whether or not a stent was deployed (p = 0.893). Interventional radiological techniques should be considered when symptoms from upper extremity central vein stenosis/occlusion are severe and disabling, or when veno-access or maintenance of patency of an ipsilateral arteriovenous (A-V) access is necessary. These results suggest an acceptable short-to medium-term solution.

Adult↗
PubMed1995

Case report: avascular necrosis of the femoral head as a complication of complex embolization for severe pelvic haemorrhage.

We present a case of avascular necrosis of the femoral head following embolization of the right medial femoral circumflex artery with alcohol after a failed prior internal iliac artery ligation to control benign pelvic haemorrhage in a 41-year-old woman. No case of late necrosis of the head of the femur as a complication of iliac artery vessel embolization to control haemorrhage has been documented previously. The problems associated with therapeutic pelvic embolization following ligation of the internal iliac artery and the disruption of the femoral head arterial supply are discussed.

Adult↗
PubMed1993

Percutaneous aspiration embolectomy.

Percutaneous aspiration thromboembolectomy (PAT) for management of a spontaneous arterial embolus, or following a complication of balloon angioplasty, was initially described in 1984. Instrument developments using a new clot aspiration system have facilitated this procedure. We report a case where PAT was successful in retrieving a spontaneous arterial embolus, and describe this new technique. We feel that PAT broadens the armamentarium of the vascular surgeon in the management of emboli to the distal circulation, where the results for operative embolectomy are frequently less than ideal.

Embolectomy↗
PubMed1993

Translumbar aortography: experience with a steerable pigtail catheter.

The authors have designed a new coaxial system for translumbar aortography and studies of the pelvis and the legs from low or high aortic puncture sites. A no. 4 French pigtail catheter with a maximum flow rate of 18 mL/s is mounted coaxially on a 32-cm-long, 20-gauge, thin-walled, two-part needle. The needle cannula accepts a guide wire of diameter 0.021 in (0.53 mm), over which the catheter can be advanced craniad for aortography or caudad for arteriography of the leg. After the first injection of contrast agent, the catheter can usually be easily redirected to complete the study. Such studies were successfully completed in 73 of 79 consecutive patients; the aorta could not be cannulated in 2, and the catheter could not be redirected in 4. The sole complications were asymptomatic extravasation of the contrast agent in one patient and moderately severe back pain that resolved spontaneously in another. The authors describe the technique, as well as variations that have been developed to overcome aortic abnormalities.

Aortography↗
PubMed1992

A phase I dose escalation trial of yttrium-90 microspheres in the treatment of primary hepatocellular carcinoma.

METHODS: Ten patients with primary hepatocellular carcinoma were treated with intraarterial instillation of yttrium-90 (Y-90) microspheres, including eight men and two women (median age, 52 years; range, 29-69 years). Four patients were treated at a targeted hepatic dose of 50 Gy, two at 75 Gy, and four at 100 Gy. RESULTS: In 8 of the 10 patients, there was a significant concentration of Y-90 in localized tumor masses with tumor-to-liver perfusion ratios from 1.0:1-10.0:1. No patient had a complete or partial response, but 10 patients had stable disease (median duration, 10 weeks; range, 5-64 weeks). The median survival was 18 weeks (range, 2-150 weeks), and three patients lived longer than 1 year. Significant bone marrow or hepatic toxicity was not seen. One patient had a radiation-induced duodenal ulcer that required surgical management. CONCLUSIONS: Intraarterial instillation of Y-90 microspheres appears to be safe and deserves additional evaluation to determine whether there is meaningful activity in patients with primary hepatocellular carcinoma.

Adult↗
PubMed1992

Radiological intervention for the failing in situ vein bypass.

With close surveillance, deteriorating hemodynamics may signal a failing in situ bypass that can be salvaged by timely intervention. The purpose of this report is to summarize our experience with in situ bypass salvage using interventional radiology. Twenty-nine patients underwent arteriography following bypass occlusion or when an ankle/brachial index reduction of greater than 0.15 was detected between two consecutive office visits. Eighteen percutaneous transluminal dilatations were performed; one patient underwent repeat dilatation after 36 months, a second had four dilatations over 40 months. Ten significant arteriovenous fistulae were identified and were successfully embolized with 3 mm coils. One patient underwent excision of a retained valve. Six patients had initial fibrinolytic therapy for graft occlusion. The morbidity of these interventions was low; one bypass was disrupted following percutaneous transluminal dilatation but was successfully salvaged surgically. The average time from the original surgery to intervention was six months (one to 26 months); and the average follow-up after intervention was 22 months (three to 62 months) over which time patency was maintained in the majority. When a correctable problem is identified with appropriate vascular lab surveillance, interventional radiology is a useful alternative to surgery for bypass salvage.

Arteriovenous Fistula↗
PubMed1990

Intraabdominal hemorrhage as a result of segmental mediolytic arteritis of an omental artery: case report.

This article describes the fifth reported case of segmental mediolytic arteritis and the second in a survivor. The patient had intraabdominal bleeding as a result of a ruptured omental artery. The pathologic and arteriographic findings are described. The pathology is characterized by segmental disruption of the medial smooth muscle cells and the initiation of mediolysis. Mediolysis is associated with marked segmental thinning of the vessel wall, often with only the adventitia intact. Fibrin is deposited at the adventitial and medial surfaces, and hemorrhage into the media may occur. As in this reported case, lysis of the adventitia leads to sudden, often catastrophic intraabdominal hemorrhage. Little associated adventitial inflammation occurred. Segmental mediolytic arteritis seems to involve the intra-abdominal muscular arteries in elderly patients with nonspecific abdominal symptoms. An angiogram showed patchy areas of narrowing involving ileal, gastroduodenal, and renal arteries that correlated with the pathologic findings observed in the excised omental arteries.

Abdomen↗
PubMed1989

Lower-extremity in situ saphenous vein grafts: angiographic interventions.

In 16 consecutive patients, thrombosis, anastomotic and intragraft stenoses, and residual venous communications (arteriovenous fistulas [AVFs]), after in situ saphenous vein bypass of femoropopliteal and infrapopliteal arteries, were treated with interventional angiographic techniques. Streptokinase infusion for graft thrombosis was performed in four patients, with long-term clinical improvement in two; in the other two, early rethrombosis was treated with surgical thrombectomy. Delayed rethrombosis occurred at 13 months in another patient. Anastomotic (six occasions) and intragraft (four occasions) stenoses in six patients were dilated with percutaneous transluminal angioplasty (PTA). Two grafts subsequently occluded, one 3 weeks and one 3 months after PTA. Residual AVFs were occluded in ten patients. Ten of 16 patients remained clinically improved without further therapy. One complication occurred: A graft stenosis developed at the site where a coil, protruding from the AVF into the graft lumen, was successfully removed and replaced.

Angiography↗
PubMed1989

Hepatocellular carcinoma: pilot trial of treatment with Y-90 microspheres.

The potential use of yttrium-90 glass microspheres in the treatment of hepatocellular carcinoma was assessed in a pilot study of seven patients. The Y-90 microspheres were injected via a hepatic artery catheter. In this group of patients, no toxicity was observed for absorbed doses of between 5,000 and 10,000 cGy to the liver and up to 32,000 cGy to the tumor itself. Tumor response was seen only at the higher absorbed doses. The new Y-90 glass microspheres can safely deliver large doses of internal radiation to hepatic tumors as long as extrahepatic shunting can be excluded. Extrahepatic shunting will be the main limitation to this form of radiation therapy.

Brachytherapy↗