ABSTRACT
Cardiovascular disease, preceded by vascular endothelial dysfunction, is a prominent cause of death in dogs. L-carnitine and taurine, well known for their antioxidative capacity, beneficially affect cardiovascular disease as well as certain dog cardiomyopathies. It is well established that vascular endothelial dysfunction precedes cardiovascular disease and that "vasoprotective factors" (NO and antioxidants) prevent apoptosis, whereas "risk factors" such as oxidized LDL, hyperglycemia, and free fatty acids trigger it in cultured human vascular endothelial cells. Whereas human vascular cell in vitro models are widely established and used for the characterisation of potential vasoprotective substances, such models are not available for canine endothelial cells. In the present study we therefore developed an in vitro model, which allows the testing of the effects of different substances on proliferation and apoptosis in canine aortic endothelial cells. This model was used to test L-carnitine, taurine, pomegranate extract, and Soy Isoflavones in comparison to reference substances (glutathione and pioglitazone) previously shown to modulate human endothelial cell function. L-carnitine and taurine neither exhibited antiproliferative nor antiapoptotic activities in the context of this study. However extracts from pomegranate and soy isoflavones dramatically reduced proliferation and apoptosis in a dose dependent fashion, being in line with a vasoprotective activity in dogs.
ABSTRACT
OBJECTIVE: Near-infrared spectroscopy (NIRS) complements online monitoring of cerebral oxygenation during aortic arch surgery. Its addition targets at an increase of safety of a complex procedure employing bilateral antegrade cerebral perfusion (BACP) and circulatory arrest under tepid blood temperatures. We report the outcome of NIRS-guided aortic arch surgery using BACP with moderate hypothermic circulatory arrest (MHCA). METHODS: Between December 2006 and December 2008, NIRS was used in 13 patients (mean age: 67.5 ± 11.3 years) undergoing aortic arch repair using BACP combined with MHCA. The diagnosis was atherosclerotic thoracic aneurysms in eight and acute aortic dissection in five patients. Seven patients had a hemi-arch replacement, six underwent frozen stent-graft arch replacement and four patients had concomitant procedures such as coronary artery bypass grafting (CABG) or aortic valve surgery. Our regimen of employing an algorithm for adaptation of perfusion modalities included the threshold of the drop in regional cerebral oxygen saturation <55% and/or a drop in the total oxygen index (TOI) of 15-20% assessed by the means of NIRS. RESULTS: The mean MHCA was 35 ± 16min and lowest bladder temperature was 26 ± 1.2°C. The mean TOI pre-MHCA was 66 ± 6.5%. Twelve out of 13 patients underwent bilateral perfusion because of unilateral drops below the threshold level of TOI (mean: 44±7.9%). In three patients, an organic psychosyndrome was observed. No patient developed permanent neurological dysfunction. CONCLUSION: NIRS-guided BACP during MHCA allows a safe approach to complex aortic arch surgery. The drop of brain oxygenation values in the contralateral hemisphere during unilateral ACP strongly suggests the routine use of BACP, when circulatory arrest under tepid temperatures is used.
