M. Heise

Retrograde reperfusion via vena cava lowers the risk of initial nonfunction but increases the risk of ischemic-type biliary lesions in liver transplantation – a randomized clinical trial

Initial nonfunction (INF) and biliary complications such as ischemic‐type biliary lesion (ITBL) remain two major complications in clinical orthotopic liver transplantation (OLT). The influence of ischemia and reperfusion injury (I/R) as a significant risk factor for both complications is widely unquestioned. A new reperfusion technique that reduces I/R injury should lead to a reduction in both INF and ITBL. One hundred and thirty two OLT patients were included in this study and randomized into two groups. Group A underwent standard reperfusion with anterograde simultaneous arterial and portal reperfusion and group B received retrograde reperfusion via the vena cava before sequential anterograde reperfusion of portal vein and hepatic artery. Serum transaminase level as a surrogate parameter for I/R injury and serum bilirubin level as a parameter for graft function were significantly reduced during the first week after OLT in group B. INF rate was 7.7% in group A and 0% in group B (Pu2003=u20030.058). ITBL incidence was 4.55% in group A versus 12.3% in group B (Pu2003=u20030.053). Retrograde reperfusion seemed to be beneficial for hepatocytes, but was detrimental for the biliary epithelium. The unexplained increased incidence of ITBL after retrograde reperfusion will be focus of further investigation.

VARIATIONS OF SURGICAL RECONSTRUCTION IN LIVER TRANSPLANTATION DEPENDING ON VASCULATURE

Abstractu2002 Background: From September 1988 through April 1998, 1000 liver transplantations were performed on 911 patients. The standard technique for liver re-vascularization to guarantee an optimal blood inflow during transplantation was modified in 19% of the cases on the arterial side and in 5.6% of the cases on the portal side as a result of unusual anatomical features and pathological changes in the vasculature of the organ recipient.In 113 transplantations, successful reconstruction of accessory vessels of the graft (12 left and 101 right hepatic arteries) was performed without complications. It is our opinion that preoperative diagnosis of the vasculature (stenoses of the celiac trunk etc.) of the organ recipient by duplexsonography and angiography is necessary. Even with the help of these tests, it is extremely difficult to diagnose a ”steal” syndrome in the splenic artery: for example, 31 of 40 patients with poor liver function received postoperative therapy for newly diagnosed ”steals”. Results and conclusions: There is no increase in complications (stenosis and thrombosis) with modifications of arterial reconstruction (4.9 vs 6.3%); however, with modification of portal reconstruction the increase is from 2.4% to 8.3%.

Correlation of Intimal Hyperplasia Development and Shear Stress Distribution at the Distal End-side-anastomosis, in vitro Study Using Particle Image Velocimetry

Low shear areas at the distal anastomosis of peripheral bypasses are thought to promote neointimal hyperplasia. In this study we evaluated the fluid dynamic environment at the distal anastomosis of peripheral bypasses by means of a new method for in vitro flow visualization and quantitative velocity field measurement. A silastic model of a distal end-side anastomosis was attached to a mock circulation loop driven by an artificial heart. High resolution velocity fields were measured by means of particle image velocimetry (PIV). The velocity vector data were used to calculate vorticity omega, strain rates ex, shear rates h and shear stresses tau. Two separations and a stagnation zone were identified by means of flow visualization. Measured velocities inside the three zones were significantly lower than in the high velocity mainstream. Calculated shear rates and shear stresses inside the zones were significantly lower than human wall shear rates. At the transition between the effective mainstream and the boundary layers high vorticity and compressive strain fields existed, indicating the presence of high shear forces. The locations of these areas corresponded to the well known zones of intimal hyperplasia. The high resolution shear stress analysis supports the low shear theory of intimal hyperplasia development. A wall diversion angle greater than 6 degrees leads to flow separation and presumed IH promotion until high shear transition areas are reached.

Rapid Development of Multiple Pseudoaneurysms After Arterial Homograft Placement

A 52-year-old woman received a preserved aorto-bifemoral homograft to treat an infection of an aorto-bifemoral Dacron graft (Vascutek, Renfrewshire, Scotland) that was implanted 5 years ago. The infected graft was completely removed during the operation. Donor and recipient blood groups were matched. The donor was a 16-year-old boy who died after traumatic brain injury after a car accident. For organ preservation, University-of-Wisconsin solution (Viaspan, Bristol-Myers Squibb, Munich, Germany) …

Primärer maligner intraluminaler Tumor der Aorta

Primary malignant tumors of the aorta are only rarely reported. We describe here our findings in a 55-year-old patient who was referred to us with progressive renal insufficiency. At angiography, right renal artery occlusion and high-grade stenosis of the left renal artery was found in this patient, who had undergone aortobiliacal reconstruction for acute Leriche syndrome 5 months previously. Histological evaluation of thrombotic material revealed an intraluminal malignant tumor to be the underlying cause. This diagnosis was then confirmed in samples harvested during angiography. CT scan showed an extension beginning 2 cm proximal to the celiac trunk. The patient was treated by thoracoabdominal resection of the aorta, including the paraaortal tissue, left side nephrectomy, and adrenalectomy. A thoracoabdominal aortic prosthesis was inserted up to the iliacal bifurcations and the celiac and superior mesenteric arteries reimplanted. Right nephrectomy followed 3 weeks later. The postoperative course was uneventful.ZusammenfassungPrimäre maligne Tumoren der Aorta sind seltene Erkrankungen. Wir beschreiben hier unser therapeutisches Vorgehen bei einem 55jährigen Patienten. Der Patient wurde mit einer progredienten Niereninsuffizienz in unserer Klinik aufgenommen. Bei der Angiographie fanden sich ein Verschluß der rechten und eine hochgradige Stenose der linken Nierenarterie. Die Diagnose des intraluminal wachsenden malignen Aortentumors wurde aus dem bei der Angiographie gewonnenen Thrombenmaterial bestätigt. Fünf Monate zuvor wurde bei der histologischen Aufarbeitung von Thrombenmaterial der Verdacht anläßlich einer aortobiiliakalen Protheseninterposition wegen eines akuten Leriche-Syndroms geäußert. Bei der Computertomographie fanden sich Veränderungen in der Aorta etwa 2 cm oberhalb des Truncus coeliacus beginnend. Es erfolgte der thorakoabdominale Aortenersatz unter Resektion der Aorta und des periaortalen Gewebes und der Nephrektomie und Adrenalektomie links. Die Prothesen-interposition wurde von der mittleren Aorta descendens bis zur Bifurkation beider Beckenarterien unter Resektion der alten aortobiiliakalen Prothese durchgeführt. Truncus coeliacus und A. mesenterica superior wurden über je ein Prothesensegment in die Aortenprothese reimplantiert. Drei Wochen nach der Erstoperation erfolgte die Nephrektomie rechts. Der postoperative Verlauf gestaltete sich unproblematisch.

Lokale Hämodynamik und Energieverluste von cruralen Bypassanastomosen, in-vitro Untersuchung mittels Particle Image Velocimetry

Objective nTo study the local hemodynamics and energy losses of crural anastomoses using Particle Image Velocimetry.