PubMed Health⌕ Search

Biomedical subjects

Raymond P Chan

Publications and source records attributed to Raymond P Chan.

8 recordsLinked to original sources
PubMed2005

Reperfusion of pulmonary arteriovenous malformations after embolotherapy.

PURPOSE: To describe the mechanisms and risk factors associated with reperfusion of successfully treated pulmonary arteriovenous malformations (PAVMs) after embolotherapy. MATERIALS AND METHODS: Among 112 consecutive patients with PAVMs treated by embolotherapy, 19 patients were identified who had 33 angiographically confirmed reperfused PAVMs. A retrospective analysis of computed tomography (CT) and angiography was performed in patients with documented reperfused PAVMs in which reperfused PAVMs were compared with nonreperfused PAVMs. CT images were examined for persistence of the aneurysm and/or draining vein after initial embolotherapy and correlated with angiography to determine the mechanism of reperfusion. PAVM and embolic agent characteristics (eg, feeding artery size and number; PAVM location; coil size, number, and location) were evaluated for association with reperfusion. The outcomes of repeat embolotherapy for reperfused PAVMs were evaluated. RESULTS: The PAVM aneurysm and/or draining vein persisted on CT after initial embolotherapy in all reperfused PAVMs and resolved in all nonreperfused PAVMs (in patients with nondiffuse PAVMs). Recanalization was the mechanism of reperfusion in 88%. Reperfusion was associated with the use of a single coil (P < .0001), oversized coils (P < .0001), coil placement more than 1 cm from the aneurysm (P < .0001), and increased feeding artery size (P < .001). Repeat embolotherapy for reperfused PAVMs was technically successful in 94% of cases. In the remaining 6% of cases, insufficient feeding artery length prevented safe repeat treatment. After a mean follow-up of 41 months, 42% of reperfused PAVMs in our series have been successfully treated again and occluded. CONCLUSIONS: Recanalization is the most common mechanism of PAVM reperfusion. Increased feeding artery diameter, low number of coils, use of oversized coils, and proximal coil placement within the feeding artery are associated with reperfusion. Distal coil placement facilitates repeat embolization if reperfusion occurs.

Adult↗
PubMed2004

Embolotherapy of pulmonary arteriovenous malformations: efficacy of platinum versus stainless steel coils.

PURPOSE: To compare the results of embolotherapy of pulmonary arteriovenous malformations (PAVMs) with use of platinum versus stainless-steel coils. MATERIALS AND METHODS: From a database of 78 consecutive patients with PAVMs treated by embolotherapy between May 1992 and September 2001, 54 patients with 306 PAVMs were selected for retrospective evaluation. Exclusion criteria were PAVMs with less than 12 months of follow-up computed tomography (CT) of the thorax (n = 15), embolotherapy with a mixture of embolic materials (n = 8), and repeat embolotherapy for previous treatment failures (n = 1). Successful treatment was defined as complete resolution of the aneurysm sac and draining vein on follow-up CT (all patients) and/or absence of contrast material flow through the PAVM on pulmonary angiography (n = 27). RESULTS: Of 267 PAVMs embolized with stainless-steel coils, 249 (93.3%) were successfully occluded (mean follow-up, 3.1 years). Of 39 PAVMs embolized with platinum coils, 35 (89.7%) were successfully occluded (mean follow-up, 2.1 years). There was no significant difference in success between the two groups (P =.5). The mean feeding artery size was significantly larger (P <.0001) in the platinum group (4.3 mm) than in the stainless-steel group (3.5 mm). Potentially serious complications included coil reflux (n = 3), PAVM perforation (n = 2), self-limited neurologic deficit (n = 2), and systemic embolization of a coil (n = 1) in the stainless-steel group, and PAVM perforation (n = 2) in the platinum group. There were no long-term sequelae. CONCLUSIONS: Coil embolotherapy is highly efficacious, with no statistically significant difference between platinum and stainless-steel coils. The slightly higher proportion of sustained occlusion with stainless-steel coils may be partly explained by the larger mean feeding artery size in the platinum group. The study is limited by the small sample size of the platinum group.

Adult↗
PubMed2002

Radiofrequency ablation of malignant hepatic neoplasms.

OBJECTIVE: To assess the safety and efficacy of radiofrequency ablation (RFA) in the treatment of malignant neoplasms of the liver. METHODS: Sixty-seven patients received RFA for primary or secondary hepatic malignancies. Patients were followed prospectively with computed tomography (CT) scanning to assess for therapeutic response, disease progression and complications. RESULTS: Eighty-eight lesions were treated, including 57 hepatocellular carcinomas, 28 metastases, 2 cholangiocarcinomas and 1 hepatic plasmacytoma. Mean tumour size was 2.7 cm (range 0.5-6.9 cm). A total of 101 ablations were performed (66 percutaneously, 35 intraoperatively). Over a mean follow-up period of 142 days, results were available for 85 lesions. Local tumour control was achieved for 61 (72%) lesions, but new distant lesions developed in 6 of these cases. Residual disease was present in 20 (23%) lesions, and 4 (5%) lesions developed local recurrence. There were 10 complications, including 1 death in a patient who developed a liver abscess and subsequently died from hepatic failure. CONCLUSIONS: RFA is safe and effective in the treatment of hepatic malignancies. Local tumour control can be achieved in most cases; however, careful surveillance is important for detecting recurrent disease, as well as new lesions distant from the treated site.

Adult↗