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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
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↗
PubMed1989

Hepatic venography in the surgical assessment of hepatic tumours.

Hepatic venography was performed on 80 patients with hepatic tumours for the pre-operative assessment of resectability. Sixty-six patients subsequently underwent laparotomy, 27 undergoing hepatic resection. Forty-two patients had metastases from colo-rectal primaries, 19 hepatocellular carcinoma and 19 a variety of other tumours. The type and frequency of the abnormalities shown on venography were noted for each tumour category and for their hepatic segmental distribution. The results of venography were compared with those of arteriography, computed tomography and ultrasound and with the findings at laparotomy. Displacement was the commonest abnormality seen while encasement or obstruction occurred less frequently and tumour invasion was rare. The sensitivity of venography in correctly identifying the segmental distribution of tumour deposits was 41%. Sensitivity was poorest with tumours in the left lobe (31%) and bilobar tumours (0%). Venography was most sensitive in detecting tumour involvement of the major segmental hepatic veins and inferior vena cava (100%). Peripheral colo-rectal metastases frequently produced no venographic abnormality. Hepatic venography provides no additional information to arteriography, computed tomography or ultrasound in patients with peripheral or bilobar tumour deposits. Some additional information may be obtained with central tumours and venography is the most accurate means of detecting tumour involvement of the major segmental hepatic veins.

Adult↗
PubMed1989

Low-dose fibrinolytic therapy for recent lower extremity thromboembolism.

Low-dose catheter-directed fibrinolytic therapy (LDCF) using streptokinase (35) and urokinase (7) was performed on 42 separate occasions in 36 patients for recent lower extremity thromboembolic occlusion. Twenty-seven grafts and 15 native arteries were treated. Causes of occlusion were known in 32 instances: native artery proximal or distal occlusive disease or both (18 vessels); bypass graft stenosis (6); aneurysm (2); embolus (4); and postangiography thrombosis (2). Twenty-nine infusions were technically successful, and patients were clinically improved by 26 of the treatments. Twelve patients had unsuccessful infusions and six underwent subsequent amputation. In all patients, infusions longer than 12 hours resulted in prolonged thrombin times and lowered plasma fibrinogen concentrations; one infusion was discontinued due to a low fibrinogen concentration. Complications occurred on 17 occasions and included hemorrhage (6), distal embolization (3), compartment syndrome (1), retrograde thrombosis during infusion (5), hypotension (1), and systemic fibrinogenolysis (1). The cumulative success rate was 44% +/- 9% at 24 months. Late rethrombosis (five instances) was more common in patients who had inflow or outflow structural lesions not corrected following successful fibrinolysis. LDCF is a useful alternative to other methods of treatment for recent onset lower extremity thromboembolic occlusion. Structural vascular lesions uncovered by successful infusion should be corrected immediately after infusion to ensure long-term patency.

Blood Vessel Prosthesis↗
PubMed1988

Intestinal angina: percutaneous transluminal angioplasty of the celiac and superior mesenteric arteries.

Percutaneous transluminal angioplasty (PTA) was performed in ten patients with chronic ischemia of the mesenteric arteries and stenoses of the celiac artery and/or the superior mesenteric artery (SMA). PTA was performed on 14 occasions, with attempted dilation of 19 arteries. PTA was technically unsuccessful in two patients. Seventeen of 19 arteries (90%) were successfully dilated in eight patients, resulting in relief of symptoms that lasted from 6 to 24 months. Symptoms recurred in five patients, and redilation in three of them relieved the symptoms. Three patients, one of them following redilation, remained asymptomatic 7-9 months following PTA. An asymptomatic intimal dissection of the SMA was the only complication attributable to the procedure. PTA of celiac and SMA stenoses is an alternative to surgical revascularization and can be repeated if symptoms recur.

Adult↗
PubMed1987

5-year results of a prospective study of percutaneous transluminal angioplasty.

This paper presents the results of a prospective study of percutaneous transluminal angioplasty (PTA) for the treatment of patients with peripheral arterial occlusive disease and identifies the variables that are predictive of long-term success. The variables believed to be important prognostically were recorded for 984 consecutive PTAs performed between July 1978 and July 1986. Success or failure was defined using a combination of clinical and objective vascular laboratory criteria. The overall long-term success was estimated by the Kaplan-Meier method and differences between curves of success rate versus time for each variable were determined by the Wilcoxon and log-rank statistics. The combination of variables associated with success were determined by the Cox proportional hazards regression model. For all cases, the initial success rate was 88.6 +/- 1.0% and at 5 years was 48.2 +/- 2.3%. The following variables, when considered individually, were associated with success (p less than 0.05): indication for PTA, site of PTA, severity of lesion, runoff, number of sites dilated, diabetes, and the occurrence of a complication. From the Cox model, by using a stepwise multiple regression procedure, the following combination of variables were found to be predictive of success (p less than 0.05): (1) indication (claudication vs. salvage), (2) site (common iliac vs. other), (3) severity of lesion (stenosis vs. occlusion), and (4) runoff (good vs. poor). For all combinations of these four significant variables, curves of the success rate versus time were calculated. In conclusion, this study has identified the combination of four variables that together predict if PTA is likely to be successful in the management of a patient with peripheral arterial occlusive disease.

Angioplasty, Balloon↗