Pneumatischer extrakorporaler Antrieb für eine doppelkammerige Blutpumpe

Zusammenfassung Es wird ein pneumatischer Antrieb für zwei intrakorporale Blutpumpen zum Ersatz des Herzens vorgestellt. Das Gesamtsystem ermöglicht die Einstellung folgender Parameter: Frequenz, Systolendauer, systolischer und diastolischer Antriebsdruck in beiden Blutpumpen. Auch die Druckanstiegsgeschwindigkeiten in beiden Ventrikeln lassen sich einstellen. Das Gerät ist so ausgelegt, daß es an einen Analogrechner angeschlossen werden kann, denn die oben angegebenen Parameter können auch elektrisch gesteuert werden.

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Pneumatic extracorporeal driving system for a double chamber blood pump

Summary A pneumatic driving system for two intracorporeal blood pumps for total heart replacement is presented. The entire system enables manual and electronic control of the following parameters: frequency, duration of systole, systolic and diastolic driving pressures in both blood pumps. The rate of pressure increase in both ventricles can also be controlled. The whole system can be connected to a computer. An automatic control and regulation is planned.

     

Automatic Control Systems for the Artificial Heart and Ventricular Assist Device

Automatic control systems for the artificial heart (AH) and ventricular assist device were developed using selected criteria of effectiveness, a mathematical model of regulation, and noninvasive measures of the hemodynamic parameters. The Sinus IS2 system was developed for control of the AH; its main component is a high-speed servomechanism that provides for the generation of pneumatic pulses. The servomechanism is controlled by automatic regulation with pressure feedback. Mean aortic pressure was used as the primary regulated hemodynamic parameter. The systems were tested using both a physical model and a physiologic experiment. Contractile insufficiency of the left ventricle was simulated in testing the control system for circulatory assistance. The studies demonstrate that automatic control systems function effectively by providing normal blood circulation in both the resting state and in certain transient processes occurring in a real, dynamic circulatory system.     

Soviet-American Collaboration on the Development of an Artificial Heart and Mechanical Circulatory Assistance

Summary: Soviet-American collaboration has resulted in more in-depth studies on the artificial heart and assisted circulation during the period of 1974–1980. The American investigators received assemblies for the Kedr (with atria and volume capacity gauges) and the Poisk and Module (without atria) artificial heart, and the pneumatic drive and automatic control system for the three artificial heart models. The Soviet investigators received from the Baylor College of Medicine the artificial heart assembly including the Vitamek pneumatic drive for the artificial heart, the biomaterials Avcothane and biomer for preparation of the artificial heart parts, and a vacuum molder for fabricating the housings of the artificial ventricles. The artificial hearts were tested on hydrodynamic benches and in animal experiments (the American artificial hearts were tested in the U.S.S.R., and the Soviet artificial hearts in the U.S.A.). Comparative study on the hydrodynamic bench, conducted according to a jointly developed, standardized method, showed that the Module artificial heart had the best flow characteristics. Valuable information was obtained concerning the Vitamek pneumatic drive and the automatic control systems, as well as the balloon pumps and drives manufactured in the U.S.S.R. and the U.S.A.     

Entwicklung implantierbarer Blutpumpen

Zusammenfassung Nach einem kurzen Überblick über die Entwicklung der Blutpumpen in den letzten 15 Jahren werden die in der Berliner Arbeitsgruppe angewendeten Entwicklungsmethoden beschrieben. Sie betreffen die Schaffung einer für die Implantation günstigen Ventrikelform, die Strömung in der Blutpumpe und durch die Ventile, die Herstellung der Ventrikel und schließlich ihre Testung auf dem Prüfstand. In einem weiteren Abschnitt werden gelöste Probleme und neue Entwicklungsziele behandelt.

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Development of implantable blood pumps

Summary After a short outline of the development of the artificial heart in the last 15 years the work of the Berlin-group is described. The methods used here concern the development of a ventricular shape suitable for implantation, the investigation of the bloodflow within the ventricle and through the valves, the fabrication of the blood pumps and finally their testing in a mock-circulation. In a further chapter the problems already solved are described and an outline of future goals is given.

     

Fatigue and Hemocompatibility of Polymer Materials

Hemocompatibility and sufficient fatigue life of biomaterials are critical in the development of artificial hearts and circulatory assist devices. In this study, three segmented polyurethanes (PUs) were compared with a fourth PU (Czech PU) and the organosilicone rubber RKM to determine the interrelationships between type of synthetic polymer, degree of structural change in cyclic loading, and hemocompatibility. Uniaxial and biaxial static strain tests were conducted. Accelerated fatigue tests were used to predict the behavior of the materials in vivo. Damage from fatigue was assessed by light transmission and light scattering methods, and the number of adhering platelets and degree of morphological change in the platelets were compared between initial and fatigued materials. The relative index of platelet adhesion and the relative form factor were also obtained. The elasticity characteristics of the PUs were shown to be substantially greater than those of RKM. RKM required reinforcement. Czech PU was shown to have good mechanical characteristics (with high elasticity and low creep). The morphology of the cells after cyclic load changed insignificantly, whereas the number of adherent platelets increased in all cases.     

Skeletal Muscle Ventricles: Frontiers in 1995

Abstract: Skeletal muscle ventricles (SMVs) constructed from electrically conditioned latissimus dorsi muscle (LDM) may become an alternative for assisting the failing heart. Left and right heart circulatory assist using SMVs has been performed successfully in both acute and chronic animal models. The configurations used to connect SMVs to the circulation have included a left atrium to aorta bypass, a left ventricle apex to aorta bypass, aortic counterpulsators, a cavopulmonary bypass, and a right ventricle to pulmonary artery bypass. One SMV used as an aortic counterpulsator functioned effectively in the circulation for more than 27 months. Recent application of the pericardium to the SMV as an inner layer and design changes in the connection of the SMV to the circulation have reduced the risk of thrombus formation and SMV rupture. Although several problems have yet to be solved, the goal of the SMV as a permanent circulatory assist device without the limitation of an external power source seems within reach.     

Outline of the International Organization for Standardization Standard for Circulatory Support Devices (ISO 14708-5)

The rapid progress of artificial heart and circulatory support devices enables us to apply them to severe heart failure patients. Many types of circulatory support devices have been developed in the United States, Europe, and Japan. This situation urged the establishment of an International Organization for Standardization (ISO) Standard for the circulatory support devices. A new work, "Cardiac Ventricular Assist Devices," was proposed to the ISO/TC150/SC6 (TC150: Technical Committee of Implants for Surgery, SC6: Sub-committee of Active Implants) in 2000, and the work was finalized for publication at a 2009 meeting of the ISO/TC150 in Kyoto. In this article, the authors would like to introduce the ISO system and the outline of the ISO Standard for Circulatory Support Devices.     

Development of Autonomous Paracorporeal and Implanted Artificial Heart and Circulatory Assist Systems

The development of autonomous systems for the artificial heart (AH) and for circulatory assistance (CA) has taken several directions. Studies relating to one direction--the development of paracorporeal and implanted systems based on thermal or electric motors--have been conducted at our institute in two stages, moving from stationary systems to totally implanted systems for long-term use. The development of these systems is described. Improvements in the linear solenoid motor, used in some of the first paracorporeal systems, enabled progress toward the development of implanted CA systems based on a reversing electrohydraulic actuator. Modifications were also made in the control system. Early animal testing of these systems indicated that they could be effective in unburdening the heart cavities during left and right bypasses. Full implantation, however, demanded that the devices have improved forms and dimensions and less weight. Smaller electromechanical systems are being developed, and we are experimenting with ways to increase the overall autonomy of the system. An orthotopic model of an implanted AH is promising. Experiments continue on the use of the body's own skeletal muscles to create a blood pump.     

Destiny of candidates for heart transplantation in the Eurotransplant heart allocation system

OBJECTIVE: We analyzed the prognosis of candidates for heart transplantation (HTx) after being listed with 'urgent status' for donor heart allocation or after ventricular assist device (VAD) implantation without application for urgent status. METHODS: Urgent status as used in this study refers to both the high urgency (HU) status awarded by Eurotransplant until August 31, 2005 and the urgent (U) status that replaced it from then on. Patients who underwent primary VAD implantation between January 2001 and December 2006 and who were listed as transplantable (T) (group VAD-prim, n=159), and patients listed primarily in urgent status before VAD implantation and/or HTx during the same period (group U-prim, n=168) were enrolled in the study. Group U-prim consists of subgroups: group U-HTx (n=123), who underwent primarily HTx in urgent status; group U-VAD (n=25), who underwent primarily VAD implantation in urgent status; patients who died in urgent status before HTx or VAD implantation (n=6); and patients in urgent status without HTx or VAD implantation (n=14). The survival rate in each group was studied. RESULTS: Survival rates after VAD implantation in group VAD-prim were comparable to those after urgent status listing in group U-prim (67.0% vs 68.5% for 1-year survival, 56.6% vs 65.8% for 2-year survival, respectively). Actuarial survival after listing for urgent status in group U-HTx was significantly better than that in group U-VAD (73.7% vs 46.0% for 1-year survival, p<0.05, log-rank test). Actuarial survival during mechanical circulatory support after the VAD implantation (censored at HTx or weaning from the device) in group VAD-prim was significantly better than that in group U-VAD (80.7% vs 56.2% for 3-month survival, p<0.001, log-rank test). CONCLUSIONS: In order to receive urgent HTx, HTx candidates may choose urgency listing without primary VAD implantation at the risk of failed donor heart allocation in urgent status. However, the prognosis of the patients in the latter situation is poor.     

Postoperative Cardiac Support with a Pulsatile Assist Pump: Techniques and Results

Since 1980 this group has employed a pulsatile assist pump(s) in 23 patients. Postoperative survival was 39% (9/23). In this group, 16 patients have required left ventricular support; 9 have been weaned from the pump, and 7 have survived (44%). Three patients required right ventricular support, and two have survived (66%). Four patients required biventricular assistance, but none survived. There have been four late deaths in this group. Of the five patients alive and well, all are New York Heart Association Class I or II. Important conclusions include the following: The pulsatile pump can adequately support the pulmonary or systemic circulation for a period of days; dramatic improvement in ventricular function is frequently observed in patients with univentricular failure; adequate right ventricular function is a major determinant of survival in a patient with pulsatile left ventricular support; preoperative cardiogenic shock and/or a prolonged time on cardiopulmonary bypass (CPB) predispose the patient to diffuse intravascular coagulation and a poor result; considerable information remains to be learned regarding the selection of assist pump candidates, optimal CPB techniques, and intraoperative identification of biventricular failure, which will further improve these results.     

In Vivo Evaluation of Zirconia Ceramic in the DexAide Right Ventricular Assist Device Journal Bearing

Zirconia is a ceramic with material properties ideal for journal bearing applications. The purpose of this study was to evaluate the use of zirconium oxide (zirconia) as a blood journal bearing material in the DexAide right ventricular assist device. Zirconia ceramic was used instead of titanium to manufacture the DexAide stator housing without changing the stator geometry or the remaining pump hardware components. Pump hydraulic performance, journal bearing reliability, biocompatibility, and motor efficiency data of the zirconia stator were evaluated in six chronic bovine experiments for 14–91 days and compared with data from chronic experiments using the titanium stator. Pump performance data including average in vivo pump flows and speeds using a zirconia stator showed no statistically significant difference to the average values for 16 prior titanium stator in vivo studies, with the exception of a 19% reduction in power consumption. Indices of hemolysis were comparable for both stator types. Results of coagulation assays and platelet aggregation tests for the zirconia stator implants showed no device‐induced increase in platelet activation. Postexplant evaluation of the zirconia journal bearing surfaces showed no biologic deposition in any of the implants. In conclusion, zirconia ceramic can be used as a hemocompatible material to improve motor efficiency while maintaining hydraulic performance in a blood journal bearing application.     

经主动脉瓣插管左心室辅助的研究

目的 探讨经主动脉瓣插管的左心室辅助方式应用于急性心力衰竭动物模型的可行性.方法 在6头猪的急性心力衰竭模型中,尝试经主动脉瓣插管的左心室辅助.并进行血流动力学及心脏超声指标的观察.结果 6头猪中有5头完成了实验.它们在血流动力学方面都显示急性心力衰竭状态的建立(P<0.05).心超指标未提示经主动脉瓣插管对主动脉瓣、二尖瓣及左心室功能的显著影响(P>0.05).在循环辅助下的血流动力学指标及部分生化指标也都较心衰状态有显著改善(P<0.05).心脏超声所示的左心室射血分数(LVEF)也有显著改善(P<0.05).结论 在急性心力衰竭模型建立后,经主动脉瓣的插管对瓣膜及左心室的功能未造成不良影响.这种循环辅助方式可以在短时间内改善急性心力衰竭的状态.     

Some Achievements from the Soviet-American Cooperation in Circulatory Assistance and the Artificial Heart: 1981–1984

The U.S.S.R. and United States have cooperated on artificial heart research and development since 1974. The exchange of information and developmental models of the artificial heart continued in the years 1981-1984. Soviet and American scientists also continued to meet regularly on specific projects relating to a variety of activities, including the testing of different heart models and biomaterials and experiments with implantation. Three symposia have been held to share research results and identify additional research problems. Joint collaboration has been both expedient and effective and has accelerated research in this area.     

Entwicklung eines standardisierten Instruments zur quantitativen und reproduzierbaren Rehabilitationserfassung nach Polytrauma (HASPOC)

Zusammenfassung. Einleitung: Im Rahmen der Versorgung schwerstverletzter Patienten rückt zunehmend die Frage des Qualit?tsmanagements, der Behandlungsergebnisse und somit die Notwendigkeit der Erfassung der Rehabilitationsgüte vor die Frage nach dem überleben des Patienten in den Mittelpunkt des Interesses. Bisherige Me?instrumente basieren auf der Erfassung von Verletzungen einzelner K?rperregionen. Scores, welche mehrere Organregionen beschreiben, wurden z. B. an Arthritispatienten entwickelt und erscheinen für Traumapatienten wenig aussagekr?ftig. Deshalb wurde an unserer Klinik in Zusammenarbeit mit der AG Polytrauma der DGU ein neues Rehabilitationserfassungsinstrument entwickelt. Methodik: Eine Gliederung in 2 Teile erm?glicht sowohl die Erfassung des subjektiven als auch des objektiven Befundes des Patienten. über einen Auswertungsscore sind anschlie?end Auswertungsberechnungen m?glich. Ergebnisse: Diese Arbeit beschreibt die Entwicklung, den Aufbau sowie die quantitative Erfassung der Ergebnisse. Hierzu z?hlt insbesondere die M?glichkeit einer regionenspezifischen Auswertung des Rehabilitationsergebnisses. Dieses standardisierte Rehabilitationserfassungsinstrument befa?t sich erstmals ausschlie?lich mit dem sehr heterogenen Patientengut der Schwerstverletzten. Es erm?glicht mittels genauestens auf diese Patienten zugeschnittener Instrumente, diese nachzuuntersuchen und Rehabilitationsdefizite aufzudecken. Implementiert sind anerkannte Instrumente zur Beantwortung spezieller Fragen, um einen Vergleich der eigenen Ergebnisse mit denen anderer Scoresysteme zu erm?glichen. Schlu?folgerung: Unter Bezug auf die Datenbank des Deutschen Traumaregisters der DGU ist nun eine prospektive Erfassung und somit genaue Qualit?tskontrolle des polytraumatisierten Patienten m?glich.      

Entwicklung eines obstruktiven Ikterus nach Einblutung in eine benigne, nicht-parasitäre Lebercyste

Benign, non-parasitic liver cysts are usually asymptomatic and found incidentally by abdominal ultrasound or CT scan. We present the case of a 68-year-old patient who showed obstructive jaundice due to a hemorrhagic liver cyst compressing the choledochal duct. Due to the location of the cyst in the porta hepatis with partial compression of central liver vessels and the meanwhile organized hematoma, operative therapy was preferred in order to prevent secondary complications such as portal vein thrombosis and to exclude a malignant neoplasm.     

Pneumatic pulsatile ventricular assist device as a bridge to heart transplantation in pediatric patients

Despite the remarkable advances with the use of ventricular assist devices (VAD) in adults, pneumatic pulsatile support in children is still limited. We report on our experience in the pediatric population. A retrospective review of 17 consecutive children offered mechanical support with Berlin Heart as a bridge to heart transplant from February 2002 to April 2010 was conducted. The median patient age was 3.9 years (75 days to 13.3 years). The median patient weight was 14.1 kg (2.9–43 kg). Before VAD implantation, all children were managed by multiple intravenous inotropes and mechanical ventilation (14) or extracorporeal membrane oxygenation (3). All patients had right ventricular dysfunction. Nine patients required biventricular mechanical support (BVAD), but in all other cases a single left ventricular assist device proved sufficient (47%). The median duration of VAD support was 47 days (1–168 days). The median pre‐VAD pulmonary vascular resistance index (Rpi) was 5.7 WU/m² (3.5 to 14.4 WU/m²). Eleven patients (65%) were successfully bridged to heart transplantation after a median duration of mechanical support of 68 days (6–168 days). Six deaths occurred (35%), three for neurological complications, one for sepsis, and two others for device malfunctioning. Since 2007, the survival rate of our patients has increased from 43% to 80%, and the need for BVAD has decreased from 86% to 30%. In two patients with Rpi >10 WU/m², unresponsive to pulmonary vasodilatator therapy, Rpi dropped to 2.2 and 2 WU/m² after 40 and 23 days of BVAD support, respectively. Seven patients (41%) required at least one pump change. Of 11 patients undergoing heart transplant, four developed an extremely elevated (>60%) panel reactive antibody by enzyme‐linked immunosorbent assay, confirmed by Luminex. All of them experienced at least one acute episode of rejection in the first month after heart transplant, needing plasmapheresis. The survival rate after heart transplantation was 100% with a median follow‐up of 25.4 months (6 days to 7.7 years). Mechanical support in children with end‐stage heart failure is an effective strategy as a bridge to heart transplantation with a reasonable morbidity and mortality. BVAD support may offer an additional means to reverse extremely elevated pulmonary vascular resistance.     

Implantation of left ventricular support under extracorporeal membrane oxygenation

Continuous-flow left ventricular assist devices (LVADs) are used to manage patients with end-stage heart failure. Protection of right ventricular (RV) function is important during LVAD implantation, but sometimes patients require temporary RV support. We describe the technique of LVAD implantation under extracorporeal membrane oxygenation (ECMO) we use in our center. This technique allows soft loading of the right ventricle once LVAD is started and even short-term RV support if required.     

Experimental videothoracoscopic cannulation of the left atrial appendix

Summary Rapid implementation of left ventricular assistance without thoracotomy for temporary support of patients with severe, life-threatening, acute cardiac power failure potentially expands applications of such support devices. A thoracoscopic technique for direct cannulation of the left atrium is described. In healthy closed-chest pigs, it proved a feasible method for effective volume unloading of the left ventricle.