L. Demircan

Fibrin gel – advantages of a new scaffold in cardiovascular tissue engineering

OBJECTIVE The field of tissue engineering deals with the creation of tissue structures based on patient cells. The scaffold plays a central role in the creation of 3-D structures in cardiovascular tissue engineering like small vessels or heart valve prosthesis. An ideal scaffold should have tissue-like mechanical properties and a complete immunologic integrity. As an alternative scaffold the use of fibrin gel was investigated. METHODS Preliminary, the degradation of the fibrin gel was controlled by the supplementation of aprotinin to the culture medium. To prevent tissue from shrinking a mechanical fixation of the gel with 3-D microstructure culture plates and a chemical fixation with poly-L-lysine in different fixation techniques were studied. The thickness of the gel layer was changed from 1 to 3 mm. The tissue development was analysed by light, transmission and scanning electron microscopy. Collagen production was detected by the measurement of hydroxyproline. Injection molding techniques were designed for the formation of complex 3-D tissue structures. RESULTS The best tissue development was observed at an aprotinin concentration of 20 microg per cc culture medium. The chemical border fixation of the gel by poly-L-lysine showed the best tissue development. Up to a thickness of 3 mm no nutrition problems were observed in the light and transmission electron microscopy. The molding of a simplified valve conduit was possible by the newly developed molding technique. CONCLUSION Fibrin gel combines a number of important properties of an ideal scaffold. It can be produced as a complete autologous scaffold. It is moldable and degradation is controllable by the use of aprotinin.

A new right ventricular assist device for right ventricular support

Right ventricular support by mechanical devices for postcardiotomy right heart failure is still associated with a high mortality. We report on the first use of a new paracardiac microaxial blood pump for postcardiotomy right heart failure in two patients undergoing emergency coronary artery bypass grafting (the first patient for a myocardial infarction complicated by a left ventricular wall rupture, the second patient for a dissection of the right coronary artery after an interventional procedure).

Experimental testing of a new left ventricular assist device--the microdiagonal blood pump.

All existing ventricular assist devices are associated with a considerable number of serious complications. This article reports on the first animal tests with a newly developed microdiagonal blood pump (MDP). Six adult female sheep weighing 80 to 90 kg underwent implantation of the microdiagonal blood pump. The inflow and outflow conduits were anastomosed to the left atrium and the descending aorta. Pump flow was adjusted to 2–3 L/minute. Hemodynamic and echocardiographic data, as well as blood samples, were measured over the entire test period of 7 days. All internal organs and the pump were explanted for thorough examination at the end of the trial. Mean arterial (range 88.5 ± 13.1–103.7 ± 10.7 mm Hg) and mean pulmonary arterial (18.3 ± 2.7–21.6 ± 20.5 mm Hg) pressures, as well as the pulmonary capillary wedge pressure (14.2 ± 3.0–16.6 ± 4.0 mm Hg), remained stable during the whole test period. Cardiac output (4.9 ± 0.7 → 3.2 ± 0.5 L/minute) decreased postoperatively caused by partial unloading of the heart. Left ventricular end diastolic (4.1 ± 0.5 → 3.6 ± 0.3 cm) and end systolic (3.2 ± 0.4 → 2.8 ± 0.5 cm) diameters, as well as the ejection fraction (57 ± 9 → 42 ± 5 %), decreased after MDP implantation and did not change during the test period. Mean number of platelets (428 ± 54 → 286 ± 66 × 103/μL) and hemoglobin (9.8 ± 1.3 → 6.3 ± 0.8 g/dL) decreased perioperatively because of surgical reasons and increased continuously in the postoperative course (platelet count and hemoglobin on day 7: 441 ± 74 × 103/μL and 7.2 ± 1.1 g/dL, respectively). Free hemoglobin was not enhanced in the postoperative course (mean value during the test period: 18.8 mmoL/L). Histologic examination of the organs did not demonstrate any infarctions of internal organs other than typical operative sequelae such as chronic pericarditis and some degree of atelectasis of the left lungs.These results demonstrate that the microdiagonal pump may be a promising alternative to the currently used ventricular assist devices, if long-term trials support these results.

Fehlabgang der linken aus der rechten Koronararterie

Zusammenfassung.Koronargefäßanomalien sind seltene, angeborene Herzfehler, die häufig chirurgisch therapiert werden müssen. Wir berichten über einen Patienten mit einem Fehlabgang der linken aus der rechten Koronararterie und diskutieren das chirurgische Vorgehen unter Verwendung einer miniaturisierten Herz-Lungen-Maschine.Abstract.Anomalies of the coronary arteries are rare, congenital heart diseases which often require surgical therapy. We report on a patient with an aberrant left coronary artery originating from the right coronary artery and discuss the operative procedure using a miniaturized heart-lung machine.