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Temporary Occlusion (temporary + occlusion)
Selected AbstractsTemporary Occlusion of the Great Cardiac Vein and Coronary Sinus to Facilitate Radiofrequency Catheter Ablation of the Mitral IsthmusJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2008ANDRE D'AVILA M.D. Introduction: Ablation of the mitral isthmus to achieve bidirectional conduction block is technically challenging, and incomplete block slows isthmus conduction and is often proarrhythmic. The presence of the blood pool in the coronary venous system may act as a heat-sink, thereby attenuating transmural RF lesion formation. This porcine study tested the hypothesis that elimination of this heat-sink effect by complete air occlusion of the coronary sinus (CS) would facilitate transmural endocardial ablation at the mitral isthmus. Methods: This study was performed in nine pigs using a 30 mm-long prototype linear CS balloon catheter able to occlude and displace the blood within the CS (the balloon was inflated with ,5 cc of air). Using a 3.5 mm irrigated catheter (35 W, 30 cc/min, 1 minute lesions), two sets of mitral isthmus ablation lines were placed per animal: one with the balloon deflated (CS open) and one inflated (CS Occluded). After ablation, gross pathological analysis of the linear lesions was performed. Results: A total of 17 ablation lines were placed: 7 with CS Occlusion, and 10 without occlusion. Despite similar biophysical characteristics of the individual lesions, lesion transmurality was consistently noted only when using the air-filled CS balloon. Conclusions: Temporary displacement of the venous blood pool using an air-filled CS balloon permits transmurality of mitral isthmus ablation; this may obviate the need for ablation within the CS to achieve bidirectional mitral isthmus conduction. [source] The histological features of microwave coagulation therapy: an assessment of a new applicator designINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 1 2003Benjamin Swift Abstract. Microwave ablation of tumours within the liver may become an adjunct or alternative to resection in patients with primary or secondary cancers. This technique combines the benefits of a large, localized coagulative effect with a single insertion of the applicator, in a significantly shorter time than comparable treatments. A new range of microwave applicators were developed and tested in animal models and both ex-vivo and in-vivo specimens of human liver at resection. At laparotomy, the applicator tip was inserted into normal liver parenchyma and tumours, with each specimen subjected to irradiation for 180 s or more and at varying power outputs. On sectioning an area of spherical blanching was observed around the applicator cavity. Microscopically a zone of coagulative necrosis was seen adjacent to the site of probe insertion. Damage to blood vessels and bile ducts occurred distal to the probe cavity suggesting the passage of heated fluid, a finding that was diminished by temporary occlusion of the hepatic vasculature (a Pringle manoeuvre). Ultra-structural damage was confirmed within the burn zone and selected liver enzymes were shown to be functioning beyond this region. We suggest this indicates the surrounding liver parenchyma is functioning normally and therefore the volume of microwave-induced damage is controllable. We are confident that the new applicator design will allow the effective treatment of larger tumours in a safe and controlled manner with a single application of energy. [source] Levosimendan cardioprotection in acutely ,-1 adrenergic receptor blocked open chest pigsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2010C. METZSCH Background: Levosimendan and volatile anesthetics have myocardial pre-conditioning effects. ,-1 adrenergic receptor antagonists may inhibit the protective effect of volatile anesthetics. No information exists as to whether this also applies to the pre-conditioning effect of levosimendan. We therefore investigated whether levosimendan added to metoprolol would demonstrate a cardioprotective effect. Methods: Three groups of anesthetized open chest pigs underwent 30 min of myocardial ischemia and 90 min of reperfusion by temporary occlusion of the largest side branch from the circumflex artery or the left anterior descending artery. One group (CTRL) served as a control, in another group (BETA), a metoprolol-loading dose was intravenously injected 30 min before ischemia, and in a third group (BETA+L), a levosimendan infusion was added to metoprolol. Myocardial tissue concentrations of glucose, glycerol, and lactate/pyruvate ratio as the primary end-points were investigated with microdialysis in ischemic and non-ischemic tissues. Results: At the end of the ischemic period, statistically significant differences were only found between CTRL and BETA+L in the ischemic myocardium, with a lower lactate/pyruvate ratio, lower glycerol, and higher glucose concentrations in BETA+L as compared with CTRL. There were no differences in non-ischemic myocardium. From 10 to 90 min of reperfusion, no more differences were found between groups. Conclusion: The cardioprotective effect of levosimendan on ischemic metabolism with a reduction in the myocardial lactate/pyruvate ratio, less glycerol accumulation, and better preserved glucose concentration does not seem to be prevented by ,-1 adrenergic receptor antagonism with metoprolol. [source] Acute Effect of Cerivastatin on Cardiac Regional Ischemia in a Rat Model Mimicking Off-Pump Coronary SurgeryJOURNAL OF CARDIAC SURGERY, Issue 6 2005Koki Nakamura M.D. The aims of this study were to investigate the optimal duration of coronary occlusion for making reversible ischemia and to examine whether cerivastatin increases myocardial tolerance against prolonged coronary occlusion. Methods: Study 1,Male Sprague-Dawley rats (350 to 450 g) underwent temporary occlusion of either left anterior descending artery (LAD; for 3, 5, 7.5, 10, 12.5, 15, or 20 min) or circumflex artery (CX; for 5, 10, or 15 min). Study 2,Rats were divided into two groups, control and cerivastatin groups, which had 0.1 mg/kg cerivastatin intravenously after anesthesia. LAD was occluded for 10, 15, or 20 minutes. In the both studies, hearts were stained to determine the area at risk (AR) and infarcted (IF) area 24 hours after reperfusion. Results: In LAD occlusion, IF/AR increased in a time dependent manner: 4.5 ± 3.2%, 9.7 ± 5.2%, 17.2 ± 3.0%, 16.8 ± 2.7%, 23.9 ± 9.5% (p < 0.01 vs. 3 min), 62.4 ± 2.9% (p < 0.0001), and 63.4 ± 2.9% (p < 0.0001) at 3, 5, 7.5, 10, 12.5, 15, and 20 min, respectively. Also in CX, IF/AR increased with time: 14.3 ± 2.3%, 25.9 ± 2.1%, and 40.9 ± 6.2% (p < 0.001 vs. 5 min) at 5, 10, and 15 min, respectively. Cerivastatin significantly reduced IF/AR at 15 minutes (43.7 ± 6.2%) and at 20 minutes (44.6 ± 5.3%) compared to control (62.4 ± 2.9% and 60.6 ± 2.5%, respectively, p < 0.05). Conclusion: Cerivastatin increased myocardial tolerance after prolonged coronary occlusion over 10 minutes, which was considered to be the upper limit for creating a regional reversible ischemia in rats. [source] Occlusion of the Middle Cerebral Artery: a New Method of Focal Cerebral Ischemia in RatsANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2005E. Cam The study in Wistar rats attempted to improve the occlusion technique of the middle cerebral artery (MCA) as a precise method for initiating stroke. In a first part it was necessary to study the exact anatomy of blood vessels of the brain in seven rats of 170-410 g body weight by corrosion cast. The lengths and diameters of defined locations of the blood vessels were measured. The temporary as well as the permanent methods were refined or replaced. The first one was completed in main training the physiological blood flow after temporary occlusion, while the permanent occlusion was performed by positioning a silicone cap in the MCA. A filament guide was introduced from the common carotid artery (CCA) via internal carotid artery (ICA) to guide the silicon cap at the branch of the MCA. Histological sections of the brain of rats showed 24 h after the permanent occlusion a reproducible infarct in the brain. This area corresponded very well with the supply of the MCA. The new occlusion method with a silicon cap was compared with the occlusion methods of CCA route and external carotid artery (ECA) route. The total infarct volume was significantly larger in the CCA route and ECA route groups than in the silicon cap group (means: CCA route 261 mm3; ECA route 191 mm3 vs. 128 mm3 silicon cap group; P < 0,05). It could be demonstrated that the new silicon cap occlusion technique imitates the pathological situation of a cerebral infarct in man. Moreover it is less invasive for the animals and more precise and reproducible regarding the infarcted area in comparison to the other occlusion methods. Based on anatomical measurements of the blood vessels the described silicon cap method can be recommended for rats of a body weight between 340,370 g. [source] Is It Possible to Create a "Mechanical" Arteriovenous Fistula in Hemodialysis Patients?ARTIFICIAL ORGANS, Issue 3 2010Attilio Ignazio Lo Monte Abstract Manual suturing still remains the best technique for the creation of vascular anastomoses on uremic patients with excellent results, despite being time consuming, difficult to perform with small vessels, and associated with a significant learning curve. We created a full mechanical arteriovenous fistula on a 65-year-old uremic patient with a new device already used in cardiac bypass surgery. The fistula was created automatically and rapidly, without the need for temporary occlusion of the artery, reducing the risk of blood clotting. We believe that mechanical devices may be useful to produce precise and fast anastomoses requiring minimal training for the surgeon. [source] The protective mechanisms of defibrotide on liver ischaemia,reperfusion injuryCELL BIOCHEMISTRY AND FUNCTION, Issue 4 2003E. O. Aydemir Abstract During some surgical interventions, temporary occlusion of the hepatic blood supply may cause ischaemia,reperfusion (I/R) injury and hepatic dysfunction. In this study the protective effect of defibrotide (DEF) was evaluated in a rat model of liver I/R injury. Four groups of rats were subjected to the following protocols: saline infusion without ischaemia, DEF infusion without ischaemia, DEF infusion with hepatic I/R, and saline infusion with hepatic I/R. After a midline laporatomy, liver ischaemia was induced by 45,min of portal occlusion. DEF 175,mg/kg,1 was infused before ischaemia in 10,ml of saline. The same volume of saline was infused into the control animals. At the end of the 45-min reperfusion interval, the animals were sacrified. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) enzyme activities were determined in haemolysates, and malondialdehyde (MDA) level in the liver tissue was measured. Tissue MDA levels were significantly higher in the I/R plus saline group compared to the sham operation control groups (p,<,0.01 and p,<,0.05, respectively). Tissue MDA levels decreased in the DEF plus I/R group compared to the I/R plus saline group (p,<,0.05), but DEF could not reduce tissue lipid peroxidation to the levels of the control sham operation groups. SOD and GSH-Px enzyme activities were significantly higher in DEF-treated animals than in the other groups (p,<,0.05). These results suggest that DEF protects liver against I/R injury by increasing the antioxidant enzyme levels. Copyright © 2003 John Wiley & Sons, Ltd. [source] | |||||||||||||