{"title":"A simple breath pattern simulator.","authors":"D Gui, R M Tacchino, T Emanuele","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":77869,"journal":{"name":"Life support systems : the journal of the European Society for Artificial Organs","volume":"4 2","pages":"155-8"},"PeriodicalIF":0.0,"publicationDate":"1986-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14867255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A three-beam laser Doppler anemometer system was used to study the flow fields created by various types of mitral heart valve prostheses under conditions of physiological pulsatile flow. The prosthetic valves studied were the Beall caged-disc valve, Björk-Shiley tilting disc valve, Medtronic-Hall tilting disc valve, and St. Jude bileaflet valve. The results indicate that all four prosthetic valve designs studied create very disturbed flow fields, with elevated turbulent shear stresses and regions of flow separation and/or stagnation. The maximum turbulent shear stresses measured were 1900 dynes/cm2 for the Beall valve, 380 dynes/cm2 for the Björk-Shiley valve, 1800 dynes/cm2 for the Medtronic-Hall valve, and 770 dynes/cm2 for the St. Jude valve. These elevated turbulent shear stresses could cause sublethal and/or lethal damage to red cells and platelets. The regions of flow separation and/or stagnation could lead to thrombus formation and/or tissue overgrowth on the valve structure, as observed on clinically recovered prosthetic valves.
采用三束激光多普勒风速仪研究了不同类型二尖瓣假体在生理脉动流动条件下的流场。所研究的人工瓣膜有Beall笼状瓣阀、Björk-Shiley倾斜瓣阀、Medtronic-Hall倾斜瓣阀和St. Jude双管瓣阀。结果表明，所研究的所有四种假体阀设计都产生了非常扰动的流场，具有升高的湍流剪切应力和流动分离和/或停滞区域。Beall阀门测量的最大湍流剪切应力为1900达因/cm2, Björk-Shiley阀门为380达因/cm2, Medtronic-Hall阀门为1800达因/cm2, St. Jude阀门为770达因/cm2。这些升高的湍流剪切应力可能对红细胞和血小板造成亚致死和/或致死损伤。在临床恢复的人工瓣膜上观察到，血流分离和/或停滞的区域可能导致瓣膜结构上的血栓形成和/或组织过度生长。
{"title":"In vitro pulsatile flow measurements in the vicinity of mechanical heart valves in the mitral flow chamber.","authors":"Y R Woo, A P Yoganathan","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>A three-beam laser Doppler anemometer system was used to study the flow fields created by various types of mitral heart valve prostheses under conditions of physiological pulsatile flow. The prosthetic valves studied were the Beall caged-disc valve, Björk-Shiley tilting disc valve, Medtronic-Hall tilting disc valve, and St. Jude bileaflet valve. The results indicate that all four prosthetic valve designs studied create very disturbed flow fields, with elevated turbulent shear stresses and regions of flow separation and/or stagnation. The maximum turbulent shear stresses measured were 1900 dynes/cm2 for the Beall valve, 380 dynes/cm2 for the Björk-Shiley valve, 1800 dynes/cm2 for the Medtronic-Hall valve, and 770 dynes/cm2 for the St. Jude valve. These elevated turbulent shear stresses could cause sublethal and/or lethal damage to red cells and platelets. The regions of flow separation and/or stagnation could lead to thrombus formation and/or tissue overgrowth on the valve structure, as observed on clinically recovered prosthetic valves.</p>","PeriodicalId":77869,"journal":{"name":"Life support systems : the journal of the European Society for Artificial Organs","volume":"4 2","pages":"115-39"},"PeriodicalIF":0.0,"publicationDate":"1986-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14078533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An alternative approach to the study of the follow-up of patients with heart prostheses is the use of the reliability theory (hazard function) and proportional hazard model (Cox's model). In a population of 480 patients who underwent AVR in the period from June 1977 to January 1983, with a mean follow-up time of 2.8 years, 16 preoperative variables were considered. From this pool of variables, six entered the regression model in a time-independent mode. These were age at operation, sex, preoperative NYHA classification, presence of AI, presence of endocarditis and presence of atrial fibrillation on ECG, none of which entered the model in the time-related mode. Another multifactorial approach, using a stepwise regression analysis to examine primary predictive factors that independently correlate with survival, while simultaneously accounting for the other previous variables, showed that the variables with additive prognostic value were age at operation, presence of AI and presence of endocarditis. Based on this model, a forecast five-year survival rate ranging from 88 to 14 per cent was found at the end of the fifth year. For the most favourable and the worst combinations of these prognostic variables, a patient-specific forecast five-year survival rate was drawn up. Our results were compared, using univariate and multivariate methods, with the results found in the literature, and the implications of this comparison were discussed.
{"title":"Prognostic variables in late follow-up of aortic valve replacement using the proportional hazard model: a study on patients using the Medtronic-Hall cardiac prosthesis.","authors":"M Abdelnoor, S N Hauge, K V Hall","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>An alternative approach to the study of the follow-up of patients with heart prostheses is the use of the reliability theory (hazard function) and proportional hazard model (Cox's model). In a population of 480 patients who underwent AVR in the period from June 1977 to January 1983, with a mean follow-up time of 2.8 years, 16 preoperative variables were considered. From this pool of variables, six entered the regression model in a time-independent mode. These were age at operation, sex, preoperative NYHA classification, presence of AI, presence of endocarditis and presence of atrial fibrillation on ECG, none of which entered the model in the time-related mode. Another multifactorial approach, using a stepwise regression analysis to examine primary predictive factors that independently correlate with survival, while simultaneously accounting for the other previous variables, showed that the variables with additive prognostic value were age at operation, presence of AI and presence of endocarditis. Based on this model, a forecast five-year survival rate ranging from 88 to 14 per cent was found at the end of the fifth year. For the most favourable and the worst combinations of these prognostic variables, a patient-specific forecast five-year survival rate was drawn up. Our results were compared, using univariate and multivariate methods, with the results found in the literature, and the implications of this comparison were discussed.</p>","PeriodicalId":77869,"journal":{"name":"Life support systems : the journal of the European Society for Artificial Organs","volume":"4 2","pages":"103-13"},"PeriodicalIF":0.0,"publicationDate":"1986-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14867253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The evaluation of electromedical equipment in the United Kingdom; moving towards improved patient care?","authors":"P J Drury, G A Harston","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":77869,"journal":{"name":"Life support systems : the journal of the European Society for Artificial Organs","volume":"4 2","pages":"99-101"},"PeriodicalIF":0.0,"publicationDate":"1986-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14867258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Alterations in host defense mechanisms associated with cardiopulmonary bypass.","authors":"M D Kazatchkine","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":77869,"journal":{"name":"Life support systems : the journal of the European Society for Artificial Organs","volume":"4 Suppl 1 ","pages":"144-52"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14867251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Gaseous microemboli production of bubble and membrane oxygenators.","authors":"D T Pearson, M P Holden, S J Poslad","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":77869,"journal":{"name":"Life support systems : the journal of the European Society for Artificial Organs","volume":"4 Suppl 1 ","pages":"198-208"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14867257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Dynamic model of gas exchanges during cardiopulmonary bypass.","authors":"P L Commin, O Stucker, M Duvelleroy","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":77869,"journal":{"name":"Life support systems : the journal of the European Society for Artificial Organs","volume":"4 Suppl 1 ","pages":"23-35"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14224548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K Mottaghy, B Oedekoven, R Bey, D Schaich-Lester, H Starmans, H Schmid-Schonbein
{"title":"Physiological aspects of extracorporeal CO2-removal in dogs and sheep with regard to clinical application.","authors":"K Mottaghy, B Oedekoven, R Bey, D Schaich-Lester, H Starmans, H Schmid-Schonbein","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":77869,"journal":{"name":"Life support systems : the journal of the European Society for Artificial Organs","volume":"4 Suppl 1 ","pages":"59-71"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14224551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Abstracts. XIII annual meeting, European Society for Artificial Organs in conjunction with the Société Française d'Hémaphérèse and Société de Chirurgie Vasculaire, Avignon, France, September 1986.","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":77869,"journal":{"name":"Life support systems : the journal of the European Society for Artificial Organs","volume":" ","pages":"1-126"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14651204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G Martinelli, S Faenza, F Petrini, A Zanoni, G Palareti, M Poggi, R Di Bartolomeo
{"title":"Modifications of the hemorrheological parameters with reference to the use of autologous or homologous blood in 25 cases of aorto-coronary by-pass.","authors":"G Martinelli, S Faenza, F Petrini, A Zanoni, G Palareti, M Poggi, R Di Bartolomeo","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":77869,"journal":{"name":"Life support systems : the journal of the European Society for Artificial Organs","volume":"4 Suppl 1 ","pages":"174-80"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14613116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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