Iwao Hioki

Silicone-coated polypropylene hollow-fiber oxygenator : Experimental evaluation and preliminary clinical use

BACKGROUND A membrane oxygenator consisting of a microporous polypropylene hollow fiber with a 0.2-microm ultrathin silicone layer (cyclosiloxane) was developed. Animal experimental and preliminary clinical studies evaluated its reliability in bypass procedures. METHODS Five 24-hour venoarterial bypass periods were conducted on dogs using the oxygenator (group A). In 5 controls, bypass periods were conducted using the same oxygenator without silicone coating (group B). As a preliminary clinical study, 14 patients underwent cardiopulmonary bypass with the silicone-coated oxygenator. RESULTS Eight to 16 hours (mean, 12.2 hours) after initiation of bypass, plasma leakage occurred in all group B animals, but none in group A. The O2 and CO2 transfer rates after 24 hours in group A were significantly higher than at termination of bypass in group B (p < 0.005 and p < 0.03, respectively). Scanning electron microscopy of silicone-coated fibers after 24 hours of bypass revealed no damage to the silicone coating of the polypropylene hollow fibers. In the clinical study, the oxygenator showed good gas transfer, acceptable pressure loss, low hemolysis, and good durability. CONCLUSIONS This oxygenator is more durable and offers greater gas transfer capabilities than the previous generation of oxygenators.

Clinical evaluation of a silicone coated hollow fiber oxygenator.

In this article, the clinical experience with a cardiopulmonary bypass (CPB) using a newly developed hollow fiber oxygenator with an ultra-thin layer of silicone is reported. A comparative study of biocompatibility between the new oxygenator and a heparin coated oxygenator is also described. The CPB was performed with a silicone coated oxygenator, Mera Excelung Binding Prim HPO 15 H-C (Group I, n = 6) or Binding Prim HPO 25 H-C (Group II, n = 10) (Senko Medical Instrument Mfg., Tokyo, Japan). Air could be vented through the silicone coated hollow fibers, and it was easy to prime the circuits. The CPB duration was 101 ± 37 min and 170 ± 64 min for Groups I and II, respectively. There were no deaths and no complications from CPB. Partial arterial pressure of O2 levels 60 minutes after the start of CPB were 529 ± 28 mm Hg and 529 ± 28 mmHg for Group I and II, respectively. of Co. levels 60 min after the start

Clinical Experience with the Nikkiso Centrifugal Pump

The Nikkiso HPM-15 is a minimally sized centrifugal pump. Preliminary results regarding clinical use of this pump for cardiopulmonary bypass (CPB) procedures have been reported previously. Recently, we have managed some additional cases using a newly developed controller. This article reports our clinical experiences with the use of this pump. We have managed 23 cases with a Nikkiso centrifugal pump. Twenty-two patients underwent CPB and 1 patient with fulminant viral myocarditis underwent percutaneous cardiopulmonary support (PCPS). With this pump, the circuit was extremely easy to prepare and deaeration was achieved readily. Hemodynamics during CPB and PCPS were stable in all cases. The increase in serum-free hemoglobin levels during CPB with this pump was as low as that seen in preliminary tests. A decrease in the platelet count was observed after the initiation of CPB with this pump; however, platelet counts returned to preoperative values 7 days after surgery. Moreover, urine output during CPB with this pump was as high as that seen in preliminary tests. No abnormalities in renal or liver function occurred during CPB. It appears that this new centrifugal pump is safe and easy to operate, and we conclude that it is useful for CPB and PCPS.

Isolated atrioventricular discordance with solitus viscera, inverted atria, D-loop ventricles, and solitus normally related great arteries: report of a rare case with successful surgical management.

tricular and concordant ventriculoarterial alignments (isolated atrioventricular discordance) is rare.1-3 Only 29 cases of this defect have been reported.4 We report the case of an infant with isolated atrioventricular discordance and complete common atrioventricular canal. To our knowledge, this case is the first successful surgical repair without atrioventricular block for isolated atrioventricular discordance with complete common atrioventricular canal.1 Clinical summary. The patient was an 8-month-old girl, weighing 3.7 kg, with poor physical development. She was a 2798-gm baby of a full-term pregnancy complicated by fetal bradycardia. Immediately after birth, she required pacemaker implantation because of sick sinus syndrome. Four months later she was noted to have congestive heart failure and was readmitted for treatment. Radiographic examination showed a left-sided stomach bubble, indicating visceral situs solitus, dextrocardia with marked cardiac enlargement, and increased vascular markings. Echocardiography showed isolated atrioventricular discordance and complete atrioventricular canal (Rastelli type A), with severe mitral and tricuspid valve regurgitation. Cardiac catheterization and angiography revealed interrupted inferior vena cava. The left-sided right atrium opened into the left-sided left ventricle and to the aorta. The left atrium was connected with a right-sided right ventricle. The pulmonary valve was leftward, anterior, and superior to the aortic valve; however, the left ventricle was anterior and to the left, with the right ventricle posterior and to the right. Systolic pressures were equal in both ventricles and in the aorta. There was a partial anomalous pulmonary The Journal of Thoracic and Cardiovascular Surgery Volume 117, Number 2 Brief communications 393

Comparative Studies of Glycoprotein Ib in Heparin Coated and Nonheparin Coated Extracorporeal Circulation Circuits

Contact between blood and artificial materials has various effects on blood. Impairment of platelet function is an especially important and well known effect, but its precise mechanism is not clearly understood. The authors constructed a circulation model to investigate the effect of extracorporeal circulation on platelet membrane glycoproteins (GPs), especially GP Ib, and to compare the changes in GP Ib in heparin coated (group C) and nonheparin coated (group N) circuits. As determined by flow cytometry, GP Ib in both groups decreased on initiating circulation, but the decrease in group N was significantly larger than that in group C. There was no observed change in GP IIb/IIIa levels in either group. The extent of shear stress induced platelet aggregation significantly decreased during circulation in both groups. Decreases in the extent of shear stress induced platelet aggregation were significantly less with the use of heparin coated circuits. In addition, the amount of GP Ib in the high speed pellet decreased progressively during circulation in both groups. In contrast, the amount of GP Ib in the Triton insoluble (low speed) pellet increased dramatically during circulation. However, expression of GP Ib in the Triton soluble platelet fraction was low in both groups. From the results, it was concluded that the cause of the decrease in platelet function during extracorporeal circulation is attributable to the internalization of GP Ib from the platelet surface inside the platelet. It also can be said that a heparin coated circuit is one effective means of controlling this change.

Early Results of Left Ventricular Reconstruction for Ischemic Cardiomyopathy with Severe Left Ventricular Dysfunction

左室心筋の広範な虚血とそれによる左室拡大および低左心機能を伴う虚血性心筋症は一般に予後不良な疾患である.この虚血性心筋症に対して,Dor手術やSAVE手術などの左室縮小形成術を行った症例の早期成績を検討した.2001年4月から2004年8月までに当施設で左室縮小形成術を施行した9例を対象とした.これらの症例に対し,on-pump beating下で冠血行再建術を行ったのち,軽度低体温で左室縮小形成術(Dor手術8例,SAVE手術1例)を施行している.また,僧帽弁閉鎖不全症(MR)合併例では僧帽弁輪形成術(MAP)を施行している.術後の検査では,LVEFは31.6±7.2%から47.8±9.4%へ改善,LVEDVIは166.7±50.4ml/m2から102.6±23.0ml/m2,LVESVIは114.4±34.7ml/m2から52.4±16.6ml/m2と縮小されていた.MRは術前1.7±1.1度から術後0.2±0.4度とMAP未施行症例においても軽快していた.Coaptation depthは9.3±3.1mmから4.5±1.4mmと減少しており,tetheringの軽減を認めた.在院死亡はなく,7/9例(77.8%)が術後NYHA I度にて良好に経過している.低心機能を伴った虚血性心筋症において,冠血行再建術に加えて左室縮小形成術を行うことにより,左室容積を縮小させ心機能は改善し,良好な予後を期待できる.

Cardiovascular surgery in chronic hemodialysis patients

Abstract Renal failure increases the morbidity and mortality of patients undergoing cardiac surgery. To investigate the adequacy of perioperative management and intraoperative techniques for cardiac operations, we retrospectively analyzed data from 25 patients (4 women and 21 men, with a mean age of 57.4 ± 7.7 years) with chronic renal failure who underwent cardiovascular surgery. The hospital mortality rate was 8.0%. Eleven postoperative complications were observed in 25 patients. The main complications were low cardiac output syndrome (with intraaortic balloon pump insertion in 4 cases), postoperative gastrointestinal tract bleeding (3 cases), and mediastinitis (2 cases). These results demonstrate that preoperative chronic renal failure increases mortality and morbidity; however, good operative outcome can be obtained with careful perioperative management.

Clinical Analysis of Mediastinal Tumors Associated with Lung Tumor.

教室では過去17年間に縦隔腫瘍症例を153例経験しており, うち肺腫瘍との合併症例は5例で, これらについて検討を加えた.男性2例, 女性3例, 年齢は35歳から76歳で, 診断は胸腺腫と肺癌症例2例, 縦隔嚢胞性腫瘍と肺癌症例2例, 胸腺腫と肺過誤腫症例1例であった.全例手術症例で, うち合併切除は3例であり, 70歳以上の高齢者2例は手術侵襲を少なくする目的で縦隔腫瘍は良性と判断し切除せず肺腫瘍のみ切除し, 術後, 縦隔腫瘍に変化はみられなかった.開胸方法は縦隔腫瘍と肺腫瘍のどちらの切除を重視するかで違いがあり, 胸骨正中切開法, 前側方切開第4肋間開胸法, 後側方切開第5肋骨床開胸法を施行した.この5例の検討により, 縦隔腫瘍に肺腫瘍を合併した症例では症例の背景因子, 術前診断, 腫瘍部位を考慮して手術術式を決定すべきであると考えられた.