Manfred Deutsch

Endothelial cell seeding of polytetrafluoroethylene vascular grafts in humans: A preliminary report

The importance of initial human trials with autologous endothelial seeding lies not only in the implementation of a promising idea but also in the fact that canine data are only partially applicable to humans. The surface area of jugular veins in humans is much smaller than in dogs and considerably longer grafts are needed. Moreover, the reproductive capacity of adult human endothelial cells under in vivo conditions, which probably determines the success of seeding more than the seeding density, is also uncertain. Therefore the efficiency of autologous endothelial seeding in humans was investigated in 18 patients undergoing distal femoropopliteal bypass surgery. The average surface area of the jugular veins was 4.9 +/- 1.7 cm2 with an average cell yield of 32.6 +/- 18.0 x 10(4). The mean number of seeded cells per square centimeter of graft surface was 3.1 x 10(3). In a follow-up extending for 14 weeks, plasma levels of platelet factor 4 and beta-thromboglobulin as well as the platelet function in the whole blood aggregometer showed significantly better results in the seeded group. Plasma thromboxane B2, uptake and survival of indium 111-labeled platelets, and Doppler ultrasound investigations also favored the seeded group, but the results were statistically insignificant. No difference at all was found for the platelet dense granule compounds, releasable adenosine triphosphate and platelet serotonin. Thus our findings did not indicate the development of a closed endothelialized surface after 14 weeks, which is a period three times as long as the one required for confluent endothelial cell coverage in dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

The Endothelium: A Key to the Future

The vascular endothelium is a complex modulator of a variety of biological systems and may well be the key to definitive success in the treatment of cardiovascular disorders. Surgically‐induced endothelial injury may occur preoperatively during cardiac catheterization and intraoperatively from mechanical manipulation, ischemia, hypothermia, and exposure to cardio‐plegic solutions. The normal endothelium is antithrombogenic and yet promotes platelet aggregation and coagulation if injured. Vasospasm, occlusive intimal hyperplasia, and accelerated arteriosclerosis can also all occur as a result of endothelial injury. Furthermore, endothelial injury is harmful even in the absence of disruption of its monolayer integrity. Thus, preservation of the endothelium should be an additional objective for all cardiovascular surgeons. Synthetic vascular grafts, cardiac valves, and artificial ventricles do not spontaneously endothelialize and thus usually require some form of anticoagulation to maintain patency. Hence, endothelialization of prosthetic implants became an attractive concept. A number of different methods of obtaining an endothelial lining of prosthetic material has since been developed; these include facilitated endothelial cell migration, and endothelial cell seeding by using either venous or microvascular endothelial cells. Manipulating the endothelium might well provide the next major advancement for therapeutic and preventative measures for cardiovascular disease.

In vitro endothelialization of expanded polytetrafluoroethylene grafts: A clinical case report after 41 months of implantation

PURPOSE Forty-one months after we performed bilateral implantation of in vitro endothelialized femoropopliteal bypass grafts in a 69-year-old patient, we obtained a central graft segment for histologic and ultrastructural investigation. METHODS Before implantation the grafts were confluently lined with autologous first passage mass cultures of pure cephalic vein endothelial cells. The precoating of the expanded polytetrafluoroethylene prosthesis was done with fibrinolytically inhibited fibrin glue. Reoperation became necessary because of symptomatic unilateral atherosclerotic lesions located in the center of one of the two in vitro lined grafts. A 21 cm long graft segment was removed and replaced by a new in vitro endothelialized expanded polytetrafluoroethylene graft. RESULTS On scanning electron microscopy a confluently covering mature endothelium was found throughout the whole length of the removed prosthesis. The endothelial identity was confirmed by a positive immunohistochemical CD 34, von Willebrand factor-staining, and the ultrastructural demonstration of Weibel Pallade bodies. The endothelium rested on a collagen IV positive basement membrane. Histologic cross sections revealed uniformly developed subintimal tissue of 1.21 +/- 0.19 mm thickness, which was separated from the intima by a distinct internal elastic membrane. The cells of this cell-rich matrix stained strongly positive for actin. Ultrastructurally, this matrix was dominated by highly contractile myofibroblasts loaded with peripherally located well-developed actin fillaments. A number of these cells also showed signs of secretory cells with a distinct endoplasmic reticulum and a Golgi complex. In areas of atherosclerotic lesions the subendothelial matrix was partially exposed, and the internal elastic membrane had to a certain extent disintegrated. Only in these areas KP-1 and MG-M1 positive foamy macrophages and CD 34 positive capillaries were found. The myofibroblasts of this diseased part of the subintimal tissue contained large lipid vacuoles. CONCLUSIONS We conclude that the confluent in vitro lining of synthetic vascular grafts with pure autologous endothelial cells facilitates graft healing, which may result in a hybrid structure with features of a native vessel.

In vitro endothelialization of a mesosystemic shunt: A clinical case report

The existence of a confluently covering endothelium that is free of any thrombotic appositions can be proved 30 days after clinical implantation of an in vitro endothelialized expanded polytetrafluoroethylene graft. The recipient of the mesosystemic H-graft was a 69-year-old man who had a thrombosed portal vein following pancreatitis. Autologous endothelial cells were obtained from the external jugular vein under local anesthesia, applying the in situ cannulation technique. After low-density plating, first-passage mass cultures of 1.22 x 10(6) endothelial cells were obtained 14 days after vein excision. After precoating was accomplished with fibrinolytically inhibited fibrin glue, a 10 mm expanded polytetrafluoroethylene graft was confluently lined with the autologous endothelial cells at a seeding density of 1.2 x 10(5) cells/cm2. After a maturation period of an additional 9 days and the microbiologic exclusion of a possible infection, an 11 cm graft segment was implanted between the superior mesenteric vein and the inferior vena cava. In spite of a patent shunt the patient had a repeat bleeding episode, needed parenteral nutrition, and died of sepsis on day 30. Immediately after the graft had been taken out, specimens were processed by scanning electron microscopy and light microscopy for the immunohistochemical proof of the endothelial nature of the surface-covering cell layer. The entire graft surface displayed a confluent cell lining that was free of any thrombotic appositions. A strongly positive stain result for both factor VIII-related antigen and the fixation-resistant CD34 molecule identified these cells as endothelial. No alpha-actin-positive cells could be detected. The underlying protein matrix was well preserved and unaltered in thickness and appearance, compared with preimplantation samples. None of the specimens showed any evidence of infection. This human demonstration of an intact endothelium on a patent venous prosthesis further establishes in vitro lining as a method that actually creates a persistent and functioning endothelium on a synthetic graft surface.

Mechanische Kreislaufunterstützung beim Herzinfarkt

Im Rahmen der vorjahrigen Tagung der Gesellschaft haben wir uber unsere ersten experimentellen Untersuchungen mit der intraaortalen Ballonpumpe zum Zwecke der mechanischen Unterstutzung des Herzens berichtet (10). Im Folgenden wird uber Ergebnisse bei der experimentellen Koronarligatur berichtet und auf erste klinische Erfahrungen mit 4 Patienten eingegangen.

Assistierte Zirkulation mit Hilfe einer intraaortalen Ballonpumpe

SummaryThis report concerns experimental investigation with intraaortic balloon pumping as a method to assist the left ventricle. This pump increases the coronary circulation and supports the left ventricle. The efficiency of the pump is demonstrated by restoration of the circulation depressed by barbiturate poisoning.ZusammenfassungEs wird über experimentelle Untersuchungen mit der intraaortalen Ballonpumpe zum Zwecke der Unterstützung des linken Herzens berichtet. Durch diese Pumpe kommt es zu einer Steigerung der Coronardurchblutung und zu einer Entlastung des linken Ventrikels. Um die Wirksamkeit dieser mechanischen Herzunterstützung zu demonstrieren, wurde eine schwere Kreislaufdepression durch Barbituratvergiftung erzeugt. Durch die Pumpe gelang es, den Kreislauf wieder zu restituieren

129. Experimentelle und klinische Erfahrungen mit der intraaortalen Ballonpumpe

SummaryAll our investigations were carried out with a technical device specially designed and built by us. We could demonstrate in over 100 animal experiments on dogs that the intra-aortal balloon pump (IABP) has a definite protective effect in cardiogenic shock. For instance, the survival rate after ligature of the ramus circumflexus of the left coronary artery rises from nil to 70%. The area of infarction is smaller when compared with controls, if the IABP is used, as a retrograde bloodflow develops via anastomoses and collaterals into the infarct area. The IABP also causes disorders of the blood coagulation in dogs and special attention has therefore to be given to blood clotting in clinical application.The IABP was used by us in 17 patients up to the present time (12 with cardiogenic shock after infarction, 4 postoperative heart-failures, 1 cardiogenic shock after recurring pulmonary embolus). Of the 12 patients with infarction 6 obtained improvement and the shock overcome. 2 of these 6 patients are still alive. Of the 4 patients with postoperative heart failure, 2 responded positively to the pump and both regained compensation. However, the patients died 10 days later as a result of a valvular thrombosis and during a technical breakdown of the pumping equipment. According to our results the heart can only be partially helped by the IABP. To achieve the ultimate rehabilitation of such moribund patients, further measures like infarctectomy, acute reconstruction of the coronary circulation or, in selected cases, a heart transplantation, would be necessary.ZusammenfassungSämtliche Untersuchungen wurden mit einer selbst konstruierten und gebauten technischen Einrichtung vorgenommen. In mehr als 100 Tierexperimenten (Hunde) konnte gezeigt werden, daß die intraaortale Ballon pumpe (IABP) beim kardiogenen Schock eine deutlich protektive Wirkung besitzt. So steigt die Überlebensrate nach Ligatur des Ramus circum flexus der linken Kranzarterie von 0 auf 70%. Das Infarktareal ist bei Einsatz der IABP im Vergleich zu Kontrollen deutlich kleiner, da es zu einem retrograden Bluteinstrom über Anastomosen und Collateralen in das Infarktgebiet kommt. Die IABP führt auch zu Störungen der Blutgerinnung bei Hunden, weswegen in der Klinik auf die Gerinnungsverhältnisse besonderes Augenmerk gerichtet werden muß.Die IABP wurde von uns bei bisher 17 Patienten eingesetzt (12 cardiogener Schock nach Herzinfarkt, 4 postop. Herzversagen, 1 cardiogener Schock nach rezidivierendem Lungeninfarkt). Von den 12 Patienten mit Herzinfarkt konnten 6 gebessert werden und der Schock behoben werden. Von diesen 6 Patienten leben derzeit noch 2. Von den 4 Patienten mit postop. Herzversagen zeigte die Pumpe bei 2 Patienten stark positive Effekte, es kam bei beiden Patienten zu einer Rekompensation. Die Patienten verstarben jedoch 10 Tage später an einer Klappenthrombose bzw. während einer Unterbrechung der Bepumpung aus technischen Gründen. Auf Grund unserer Ergebnisse kann durch die IABP das Herz nur partiell unterstützt werden. Zur endgültigen Rehabilitierung dieser todkranken Patienten sind jedoch zusätzliche Maßnahmen wie eine Infarktektomie, eine akute Rekonstruktion der coronaren Strombahn oder in ausgewählten Fällen eine Herztransplantation notwendig.

Mechanische Unterstützung des Kreislaufes

ZusammenfassungDie technischen und biologischen Fortschritte haben die Entwicklung verschiedener Systeme zur mechanischen Unterstützung des Kreislaufes ermöglicht. Die Übertragung dieser meist experimentell erprobten Methoden in die Klinik eröffnet neue Aspekte bei der Behandlung von Herz- und Kreislauferkrankungen.Neben der einfach auszuführenden intra- oder extrathorakalen Herzmassage hat die Anwendung der Herz-Lungen-Maschine zur temporären Unterstützung oder zum Ersatz des Herzens größte klinische Verbreitung gefunden. Außer diesen beiden Arten der Unterstützung gibt es noch solche, deren Erprobung noch kaum über das Versuchsstadium hinaus ist. Nach ihrer Funktion lassen sie sich in 3 Gruppen teilen, die zum Herzen parallel geschalteten Entlastungspumpen, die arterielle Gegenpulsation und das Kunstherz.Beim Linksherz-By-pass wird das Blut über eine extraoder intrakorporale Pumpe unter Umgehung des linken Ventrikels in das arterielle System gepumpt. Dadurch wird das linke Herz teilweise entlastet.Bei der arteriellen Gegenpulsation wird in der Diastole eine künstliche arterielle Druckwelle erzeugt und in der Systole das Herz mechanisch entlastet. Dies geschieht entweder durch Absaugen des arteriellen Blutes in einen Hilfsventrikel oder aber durch Kollabieren eines in der Aorta liegenden Kunststoffballons. Der artifiziell, gesteigerte diastolische Druck führt zu einer Verbesserung der Koronardurchblutung. Die intakte Funktion der arteriellen Gegenpulsation ist nur bei suffizienten Aortenklappen gegeben. Ebenso ist es schwierig, bei Herzrhythmusstörungen die Druckwelle exakt in die Diastole zu legen. Dadurch ist die klinische Anwendung dieser Systeme beschränkt.Die radikalste Form der Kreislaufunterstützung stellt wohl der totale mechanische Herzersatz durch ein Kunstherz dar. Die Fragen des Kunststoffes, der Klappenmechanismen und der physiologischen Steuerung des Herzens harren noch einer Lösung.Trotz vieler ungelöster Probleme ergeben sich aus der Verschiedenartigkeit der Prinzipien der mechanischen Unterstützung des Herzens vielfältige klinische Anwendungsmöglichkeiten für die Zukunft.SummaryProgress which has been made in various technical and biological fields, has made possible the development of various systems of mechanical assistance of the circulatory system. The introduction of these laboratory-tested methods into the clinic opens new horizons in the treatment of heart and circulatory diseases. Besides simple intra-and extrathoracic heart massage, the application of the heart-lung maschine for temporary relief or heart replacement found wide-spread use in the clinic. In addition to these methodes of heart assistance there are still others which are at present hardly beyond the experimental stage. They can be devided into three groups, according to their function: By-pass pumps, which are connected to the circulatory system in parallel to the heart, the arterial counterpulsation and the artificial heart.In left heart by-pass blood is pumped through an intra- or extracorporeal pump into the arterial system, bypassing the left ventricle, and thus partially unburdening the left side of the heart.In arterial counterpulsation, an artificial arterial pressure wave is produced during the diastole, and the heart is mechanically unburdened and assisted during the systole. This is brough about by withdrawing the arterial blood into an auxiliary ventricle or by the collapsing of a plastic balloon previously placed in the aorta. The artificially-raised diastolic pressure leads to an improvement of the coronary perfusion. The intact function of arterial counterpulsation occurs only with sufficient aortic valves. It is also difficult in disturbances of cardial rhythm to coordinate exactly this counter-pressure-wave. For this reason, this method has been employed quite infrequently in the clinic.The total, mechanical replacement by an artificial heart represents probably the most radical form of circulatory assistance. The problems of the adequate plastic, of valve mechanism, and of physiological triggering awaits even today an answer. But inspite of the many unsolved problems, there results a variety of possible clinical applications for the future from the multiplicity of the principles of mechanical support for the heart.