A Large-Diameter Vascular Graft Replacing Animal-Derived Sealants With an Elastomeric Polymer.

INTRODUCTION: To assess the safety and efficacy of an experimental large-diameter vascular graft externally sealed with an elastomeric polymer when used as an interposition graft in the descending aorta of sheep. METHODS: The experimental vascular grafts as well as control gelatin sealed interposition grafts were inserted into the descending aorta of juvenile sheep. The grafts were assessed by time to hemostasis and blood loss during surgery and hematology and biochemistry panels at distinct time points. Magnetic resonance imaging (MRI) was performed at 3 and at 6 mo after surgery, after which the animals were euthanized and necropsies were carried out including macroscopic and microscopic examination of the grafts, anastomoses, and distal organs. RESULTS: All animals survived the study period. There was no perceivable difference in the surgical handling of the grafts. The median intraoperative blood loss was 27.5 mL (range 10.0-125.0 mL) in the experimental group and 50.0 mL (range 10.0-75.0 mL) in the control group. The median time to hemostasis was 5.0 min (range 2.0-16.0 min) minutes in the experimental group versus 6.0 min (range 4.0-6.0 min) in the control group. MRI showed normal flow and graft patency in both groups. Healing and perianastomotic endothelialization was similar in both groups. CONCLUSIONS: The experimental graft has a similar safety and performance profile and largely comparable necropsy results, in comparison to a commonly used prosthetic vascular graft, with the experimental grafts eliciting a nonadherent external fibrous capsule as the major difference compared to the control grafts that were incorporated into the periadventitia. Survival, hemostatic sealing, and hematologic and radiologic results were comparable between the study groups.

Rapid deployment aortic valve replacement in a minimal access setting: intermediate clinical and echocardiographic outcomes.

OBJECTIVES: Transcatheter procedures have overtaken conventional operations in Germany. Considering that this is a highly competitive field, a rate of 25% for minimal access aortic valve replacement seems to be disappointingly low. One way to promote minimal access techniques is through the systematic use of rapid deployment valves. METHODS: A total of 143 patients underwent rapid deployment aortic valve replacement via upper right hemisternotomy between March 2012 and September 2015. All patients were followed up annually. Echocardiographic assessment of the valve was performed after 12 months. The cumulative follow-up time was 275.2 patient-years. The median follow-up time was 1.9 years. RESULTS: The mean age was 76.4 ± 6.2 years, and the mean logistic EuroSCORE was 11.0 ± 4.3%. Early all-cause mortality was 2.8% (n = 4). Actuarial survival after 1 year was 91.6 ± 2.4%, and after 3 years, it was 84.4 ± 3.6%. Mean transprosthetic gradient after 12 months was 10.3 ± 3.8 mmHg. New onset of higher grade paravalvular leakage did not occur during the follow-up period. Perioperatively, higher grade paravalvular leakage (aortic insufficiency >1+) occurred in 2 cases (1.4%) . CONCLUSIONS: Rapid deployment aortic valve replacement can be performed safely in a minimal access setting with low complication rates and good haemodynamic results. Therefore, rapid deployment valves are a relevant option in minimal access surgery.

Low-flow lower body perfusion for spinal protection in a frozen elephant trunk simulation model.

OBJECTIVES: The frozen elephant trunk (FET) procedure using isolated selective cerebral perfusion (SCP) at moderate hypothermia is associated with an increased risk for spinal cord ischaemia. The aim of this study was to evaluate the benefit of a combined selective cerebral and low-flow lower body perfusion (CLBP) in a porcine model. METHODS: Twenty pigs (46 ± 5 kg) were cooled on cardiopulmonary bypass (CPB) to 28°C. After aortic clamping and occlusion of the thoracic segmental arteries (TSAT4-T13), a pressure-controlled SCP (50 mmHg) was established for 90 min. Randomly, in n = 10 animals, an additional lower body perfusion (LBP) was performed with 15 ml/kg/min (CLBP). Regional spinal cord blood flow (SCBF), cerebrospinal fluid pressure (CSFP) and motor-evoked potentials (MEPs) were registered at six time points. The animals were sacrificed after 120 min of weaning from CPB, and the spinal cord was analysed histologically using a schematic scoring system (0 = normal, 8 = total necrosis). RESULTS: Isolated SCP led to an SCBF decrease from 18.5 ± 9.4 to 0.9 ± 1.4 ml/min/100 g in the L1-L5 region (P = 0.005). CLBP preserved an almost physiological lumbar SCBF of 11.3 ± 5.3 ml/min/100 g. CSFP decreased in both groups during cooling and SCP/CLBP to 70-80% and increased during reperfusion to 150%, without showing significant differences between groups. The MEP amplitude decreased in both groups, with certain regional differences: T7-T11. MEP recording revealed a more pronounced amplitude decrease in the CLBP group (52.5 ± 2.0 vs 71.3 ± 0.9%), but MEP amplitudes recovered in both groups (SCP: 73.7 ± 0.5 vs CLBP: 82.6 ± 0.1%). During selective hypothermic perfusion, SCP-treated animals showed significant lower MEP amplitudes, when compared with CLBP-treated animals: 60 ± 9 vs 90 ± 3% (P < 0.001). After weaning, CLBP animals showed a better MEP recovery, especially in the L1-L5 region (99 ± 7 vs 70 ± 13%; P < 0.001). The histological analysis did not show significant differences in the necrosis extension in the thoracic spinal cord. A different situation was seen in the L1-L5 area: all animals with isolated SCP, but only 50% of the CLBP animals presented a score of >5. A higher grade of lumbar ischaemia could be seen after isolated SCP (score: 5.9 ± 0.6 vs 3.6 ± 2.9). CONCLUSION: The prolonged SCP provides an insufficient lumbar spinal cord protection during the FET procedure at 28°C. The use of a low-flow LBP in addition to SCP may reduce functional and structural spinal damage.

24-hour performance of albumin dialysis assessed by a new two-compartment in vitro model.

Extracorporeal albumin dialysis as a measure to remove water soluble and protein bound toxins simultaneously has been shown to improve complications of liver failure. However, recent research suggests that only treatments associated with a measurable improvement of patient's albumin binding function by effective removal of albumin bound toxins leads to better survival. The aim of the present work was to develop a test platform for upcoming devices to evaluate long term effectiveness on toxin removal and improvement of patients' albumin binding capacity. The classical one compartment model consisting of a closed pool of toxin spiked plasma was combined with continuous infusion of water soluble and protein bound toxins mimicking physiological rebound rates reflected in the literature. The model was used to demonstrate the effect of stabilizer contamination of dialysate albumin on toxin clearance and albumin binding function. In comparison to the classical one compartment model, the two compartment model allows for long term effectiveness tests of liver assist devices not only for strongly albumin-bound, but also water-soluble molecules. The limitations of commercial albumin overloaded with caprylate ligands (5:1 molar ratio) were demonstrated by presenting a significant improvement of albumin binding function using 80 g deligandized albumin compared to no significant improvement using the standard 120 g albumin as dialysate. The new two compartment model allows for pre-clinical evaluation of new upcoming devices aiming for improvement of patients' albumin binding function as a measure for clinically meaningful extracorporeal detoxification of albumin-bound toxins.