There is a trend towards using the axillary artery cannulation (AXC) site for cardiopulmonary bypass surgery in patients requiring acute type A aortic dissection (AAD) repair. However, AXC has not been established as a routine procedure, because there is controversy about its clinical advantage when compared with femoral artery cannulation (FAC). This meta-analysis assesses major short-term outcomes in patients undergoing acute AAD repair with AXC or FAC using non-randomized retrospective studies dating from 1992 to 2011 comparing AXC and FAC for major outcomes. Outcomes of interest were short-term mortality, neurological dysfunction and malperfusion. The fixed-effects model was used. Sensitivity and heterogeneity were analysed. Analysis of nine non-randomized studies comprising 715 patients [AXC, 359 (50.2%) and FAC, 356 (49.8%)] showed a significantly lower incidence of short-term mortality in the AXC group [odds ratio, 0.25, 95% confidence interval (CI) (0.15, 0.42), χ² = 7.23, P < 0.01]. The pattern of incidence of neurological dysfunction among the AXC group [odds ratio, 0.46, 95% CI (0.29, 0.72), χ² = 9.01, P < 0.01] was similar. The incidence of malperfusion did not differ [odds ratio, 0.84, 95% CI (0.37, 1.90), χ² = 2.25, P = 0.67]. Because no study was a randomized trial, our results are more uncertain than indicated by the 95% CI. Nevertheless, AXC seems to give better short-term mortality and neurological dysfunction rates than FAC.

To test the hypothesis that angiotensin II (Ang II) could enhance noradrenaline (NA) release from sympathetic nerve endings of the aorta thus contributing to the up-regulation of matrix metalloproteinase 2 (MMP-2) during the formation of aortic dissection (AD). Ang II, NA, MMP-2, MMP-9 of the aorta sample obtained during operation from aortic dissection patients were detected by High Performance Liquid Chromatography and ELISA and compared with controls. Isotope labelling method was used to test the impact of exogenous Ang II and noradrenaline on the NA release and MMP-2, MMP-9 expression on Sprague Dawley (SD) rat aorta rings in vitro. Two kidneys, one clip, models were replicated for further check of that impact in SD rats in vivo. The concentration of Ang II, MMP-2, 9 was increased and NA concentration was decreased in aorta samples from AD patients. Exogenous Ang II enhanced while exogenous NA restrained NA release from aortic sympathetic endings. The Ang II stimulated NA release and the following MMP-2 up-regulation could be weakened by Losartan and chemical sympathectomy. Beta blocker did not influence NA release but down-regulated MMP-2. Long term in vivo experiments confirmed that Ang II could enhance NA release and up-regulate MMP-2. AD is initiated by MMP-2 overexpression as a result of increased NA release from sympathetic nervous endings in response to Ang II. This indicates an interaction of RAS and SAS during the formation of AD.