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Biomedical subjects

Christopher L Corless

Publications and source records attributed to Christopher L Corless.

59 records · Page 4Linked to original sources

Percutaneous bioprosthetic venous valve: a long-term study in sheep.

A long-term evaluation of a new percutaneously placed bioprosthetic, bicuspid venous valve (BVV) consisting of a square stent and small intestinal submucosa (SIS) covering was performed in 12 sheep. Of 26 BVVs placed into the jugular veins, 25 exhibited good valve function on immediate venography and 22 on venograms obtained before the sheep were killed. Gross and histologic examination results demonstrated incorporation of remodeled and endothelialized SIS BVVs into the vein wall. Slight to moderate leaflet thickening was found mostly at their bases. Percutaneously placed SIS BVV is a promising one-way, competent valve that resists venous back-pressure while allowing forward flow.

Animals↗

Experimental percutaneous extrahepatic portacaval shunt creation by transjugular approach in Swine.

The purpose of the study was to evaluate the feasibility of the creation of a percutaneous extrahepatic portacaval shunt (PEPS) in swine by a transjugular approach and to find a suitable stent-graft to use in PEPS. In 12 swine, the extrahepatic portal vein (PV) was entered from the inferior vena cava (IVC) by a needle system introduced from the transjugular approach. A catheter introduced through the transhepatic approach served as a target. Five types of stent-graft consisting of homemade Z stents and a polytetrafluoethylene cover were explored for PEPS creation. Eight animals had follow-up venograms up to 6 weeks or until the shunt became severely stenotic. Gross and histologic examinations were performed after the final follow-up venography. The PV punctures and stent-graft placement were difficult, but the PEPS was established in all animals. In four animals, the stent-graft failed to adequately cover the tract, causing severe hemorrhage. Only two shunts remained patent up to 6 weeks. The other shunts exhibited severe stenosis or occlusion. At gross examination, all shunts traversed the liver parenchyma of the caudate lobe surrounding the IVC. The extravascular PEPS portion was 4 mm to 2 cm long. All shunts entered the PV close to the splenomesenteric junction and exhibited neointimal formation. Shunt stenoses were caused by neointimal hyperplasia and occlusions by a superimposed thrombus. PEPS can be created by the transjugular approach in swine, but only the PV shunt entrance is extrahepatic. None of the tested rigid stent-grafts were suitable for PEPS creation. A short flexible stent-graft with flanged ends is suggested for further exploration.

Animals↗

Effects of blood flow and/or ventilation restriction on radiofrequency coagulation size in the lung: an experimental study in swine.

The purpose of this study was to investigate how the restriction of blood flow and/or ventilation affects the radiofrequency (RF) ablation coagulation size in lung parenchyma. Thirty-one RF ablations were done in 16 normal lungs of 8 living swine with 2-cm LeVeen needles. Eight RF ablations were performed as a control (group G1), eight with balloon occlusion of the ipsilateral mainstem bronchus (G2), eight with occlusion of the ipsilateral pulmonary artery (G3), and seven with occlusion of both the ipsilateral bronchus and pulmonary artery (G4). Coagulation diameters and volumes of each ablation zone were compared on computed tomography (CT) and gross specimen examinations. Twenty-six coagulation zones were suitable for evaluation: eight in G1, five in G2, seven in G3, and six in G4 groups. In G1, the mean coagulation diameter was 21.5 +/- 3.5 mm on CT and 19.5 +/- 1.78 mm on gross specimen examination. In G2, the mean diameters were 26.5 +/- 5.1 mm and 23.0 +/- 2.7 mm on CT and gross specimen examination, respectively. In G3, the mean diameters were 29.4 +/- 2.2 mm and 27.4 +/- 2.9 mm on CT and gross specimen examination, respectively, and in G4, they were 32.6 +/- 3.33 mm and 28.8 +/- 2.6 mm, respectively. The mean coagulation volumes were 3.39 +/- l.52 cm(3) on CT and 3.01 +/- 0.94 cm(3) on gross examinations in G1, 6.56 +/- 2.47 cm(3) and 5.22 +/- 0.85 cm(3) in G2, 10.93 +/- 2.17 cm(3) and 9.97 +/- 2.91 cm(3) in G3, and 13.81 +/- 3.03 cm(3) and 11.06 +/- 3.27 cm(3) in G4, respectively. The mean coagulation diameters on gross examination and mean coagulation volumes on CT and gross examination with G3 and G4 were significantly larger than those in G1 (p < 0.0001, p < 0.0001, p < 0.0001, respectively) or in G2 (p < 0.05, p < 0.005, p < 0.005, respectively). Pulmonary collapse occurred in one lung in G2 and pulmonary artery thrombus in two lungs of G3 and two lungs of G4. The coagulation size of RF ablation of the lung parenchyma is increased by ventilation and particularly by pulmonary artery blood flow restriction. The value of these restrictions for potential clinical use needs to be explored in experimentally induced lung tumors.

Animals↗

Outcome following surgical therapy for gastrointestinal stromal tumors.

We have pursued an approach of complete resection for patients with gastrointestinal stromal tumors (GISTs), including multivisceral resection, for patients with disease involving adjacent organs. We have also extended the limits of resection to include patients with metastatic disease who were treated with imatinib mesylate. The aim of this study is to report the outcomes and prognostic factors associated with this clinical approach. Study subjects were identified using the pathology database at our institution; for inclusion in the study group, patients must have undergone surgical resection for a KIT-positive gastrointestinal stromal tumor between January 1992 and March 2004. We calculated survival by using the Kaplan-Meier method. Univariate and multivariate analysis was performed using log-rank analysis and the Cox proportional hazards model. Thirty-four patients met the study criteria. Fifty-nine percent of patients had GISTs of gastric origin, 20.6% had duodenal GISTs, and the remainder was comprised of a variety of other sites. Twenty-two (64.7%) patients underwent single-organ resection, and 12 patients (35.3%) underwent multivisceral resection. Estimated actuarial survival at 5 years was 65.2%. Seven patients (five patients with metastases, one patient with locally advanced disease, and one patient with organ-confined disease) received imatinib mesylate. Independent predictors of poor survival included incomplete resection, metastatic disease at presentation, and high mitotic index. Mitotic index and the presence of metastases remain the primary predictors of postoperative survival. Complete surgical resection, even if multivisceral resection is required, is associated with improved survival.

Biomarkers, Tumor↗