ULTRASONOGRAPHIC ASSESSMENT OF METALLIC CLIP CAROTID ANASTOMOSIS IN SHEEP

The aim of this study was to use ultrasonography to assess an experimental carotid arteriotomy followed by end-to-end anastomosis in the lamb. Animals were subjected to an experimental surgical procedure consisting of a right carotid artery arteriotomy and subsequent end-to-end anastomosis with nonpenetrating metallic clips. Left side arteries were used as control. Duplex ultrasonography was performed postoperatively to assess the evolution of the experimental anastomosis. Measurements were made on the right carotid to assess blood flow, peak systolic velocity, and end diastolic velocity, as well as arterial diameter. Animals were periodically checked during the six-month postoperative period. Operated vessels appeared normal during follow up, with pulsatile movements and size similar to non operated carotid arteries. A hyperechoic band, perpendicular to the vessel main axis, was seen on the longitudinal image in operated arteries, but not in the control group. This band corresponded to the anastomosis area, where the clips were positioned. No image suggestive of thrombosis was observed in any operated artery, and blood flow was maintained through the experiment. Finally, a decrease of vessel lumen diameter was evidenced at the level of the anastomosis during the first 30 postoperative days, but it was not present after the 90th postsurgical day. Duplex ultrasonography is a useful imaging technique for the assessment of anatomical details, acoustical properties of the vascular lumen, and study of the intimal surface and vessel wall in growing arteries subjected to surgery. Metallic clips as suturing technique in arterial anastomosis allow for normal vascular growth, as shown by the evolution of flow velocity and vessel diameter.     

太岳山油松基因保护林的研究(Ⅰ)——林分组成与结构的研究

该文依据山西太岳林区油松基因保护林的外业调查材料 ,对该林分的组成和结构做了初步分析 .调查地的植物种类丰富 ,其中木本植物种类约占太岳林区的 1 5 .5 % ;枯死木以小径级木为主 .油松保护林是在 6 0～ 70a前 ,受某种干扰后形成的相对同龄次生林 .大约在 40～ 5 0年生时 ,出现过一次小的干扰 .由于密度过大 ,油松的形状比 (H/D)值偏高 .更新层中 ,油松幼苗集中在林隙中 ;而辽东栎幼苗均匀分布在调查地中 ,但不能成为更替层 .说明两树种在幼苗阶段对光的要求不同 ,油松幼苗喜光 ;辽东栎幼苗较耐荫 ,但在一定年龄之后必须有足够的光照 .这也是调查地内没有成年辽东栎的原因之一     

Submaximal Exercise Testing Using Lactate Threshold and Venous Oxygen Tension as Endpoints in Normal Dogs and in Dogs With Heart Failure

Twelve normal dogs and 7 dogs with experimentally induced heart failure were chronically instrumented to measure hemodynamic variables and blood gas tensions at rest and during graded treadmill exercise. Three groups of 4 normal dogs each (group 1, 15 to 20 kg; group 2, 21 to 30 kg; group 3, 31 to 40 kg) were exercised on a treadmill at a 16% grade at 1, 2, and 3 miles per hour, and at a 22% and a 26% grade at 3 miles per hour (5 total exercise levels) until blood lactate concentration increased to a value greater than 1 mmol/L. Blood lactate concentration and blood gas tensions were measured 5 and 15 minutes after starting exercise, and cardiac output was measured between 8 and 10 minutes of exercise. Results indicated that the same exercise protocol could be used for dogs ranging in size from 15 to 40 kg. Blood lactate concentration increased in normal dogs at varying workloads, but always at or above a workload of 3 miles per hour at a 16% grade. Dogs with class IV heart failure always experienced an increase in blood lactate concentration when walked at 1 mile per hour at a 16% grade for 5 minutes. A femoral vein Po₂ between 21 and 24 mm Hg in normal dogs, and between 16 and 22 mm Hg in dogs with heart failure was always associated with an increase in blood lactate concentration. The primary problem with this exercise protocol was the unwillingness of some dogs to walk on the treadmill during the preselection phase. We conclude that we have devised a submaximal exercise test that can be used to evaluate exercise capability in dogs ranging in size from 15 to 40 kg, that the described exercise protocol can be used to identify decreased flow reserve in dogs with class IV heart failure induced by rapid ventricular pacing, and that either femoral vein oxygen tension or blood lactate concentration can be used as the endpoint for submaximal exercise testing in dogs. J Vet Intern Med 1996;10:21–27. Copyright©1996 by the American College of Veterinary Internal Medicine.     

Spontaneous Occurrence of Hepatic Lipidosis in a Group of Laboratory Cats

Clinical signs consistent with hepatic lipidosis occurred in six obese adult laboratory cats, housed in a group cage, 6 to 7 weeks after changing their diet from a commercial to a purified diet. The affected cats lost 30 to 40% of their body weight in this time period. This rate of weight loss is compatible with little or no food intake. For treatment, 5 cats were tube-fed three or four times daily with a high-fat liquid diet supplemented with L-citrulline and choline. All cats tolerated the diet, which contained 35% protein on an energy basis. Substantial voluntary food intake resumed 12 to 16 days after initiating treatment. The sixth cat was euthanatized. These observations suggest that 6 to 7 weeks of anorexia, associated with 30 to 40% weight loss, can induce hepatic lipidosis in obese but otherwise healthy cats, and confirm that with appropriate management the prognosis for cats with hepatic lipidosis is favorable.     

Balloon Dilation of Congenital Subaortic Stenosis in the Dog

Balloon dilation during cardiac catheterization was evaluated for the treatment of congenital subaortic stenosis (SAS) in nine dogs. Under general anesthesia, bilateral cardiac catheterization was performed through the right jugular vein and carotid artery. Thermodilution cardiac output, and left ventricular and aortic root pressures and angiograms were obtained before and after balloon dilation. Balloons measuring 18–20 mm in diameter and 30–40 mm in length were positioned across the stenosis and three inflations 4–5 minutes apart were performed. There was no significant change in cardiac output, aortic pressure, or degree of aortic regurgitation after balloon dilation. For the entire group balloon dilation resulted in significant decreases in left ventricular systolic pressure (-61.2 ± 37.2 mm Hg [mean change ± SD], range -14 to -123), mean systolic pressure gradient (-39.6 ± 24.4 mm Hg, range –8.4 to -72.2), and peak systolic pressure gradient (-64.3 ± 46.5 mm Hg, range –17 to –143). Calculated left ventricular outflow cross-sectional area increased significantly (+.4 ± .5 cm², range –.06 to + 1.30). Clinical signs improved in the five symptomatic dogs. Individual hemodynamic responses varied widely, but the magnitude of improvement correlated with the severity of obstruction. Three dogs showed a decrease of 60% or greater (≥100 mm Hg), and six dogs showed a decrease of 25–50% (17–71 mm Hg) in peak systolic gradient after balloon dilation. Complications were frequent but most were transient and manageable. These preliminary results suggest that balloon dilation can acutely decrease outflow resistance in dogs with SAS and may be effective therapy for some affected dogs.