These highly selected data support the potential value of chimney and periscope graft techniques for patients with challenging aortic aneurysm morphology. There is a lack of medium- and long-term follow-up data.

Arterial stiffness is an independent predictor of cardiovascular events in a hypertensive population. Serum levels of matrix metalloproteinase (MMP)-9 are associated with arterial stiffness and predict cardiovascular risk. We investigated the role of MMP-9 polymorphism À1562C4T on blood pressure (BP) and arterial stiffness in a newly diagnosed hypertensive population. Untreated hypertensive patients (n ¼ 215, mean age 46713 years) were studied. Supine BP, carotid-femoral pulse wave velocity (PWV) and augmentation index were assessed. Serum biochemistry and plasma MMP-9 concentrations were measured and genotyping performed following extraction of genomic DNA. BP, aortic PWV and serum MMP-9 levels were significantly higher in T-allele carriers of the À1562C4T polymorphism with a significant gene-dose effect (Po0.0001). In a stepwise regression model adjusting for known or likely determinants, the 1562C4T polymorphism emerged as an independent predictor of systolic BP (R 2 ¼ 0.25, Po0.0001), diastolic BP (R 2 ¼ 0.16, Po0.0001) and PWV (R 2 ¼ 0.47,Po0.0001). This is the first study to show the effect of MMP-9 polymorphism on BP and aortic stiffness in a hypertensive population. These results suggest that hypertensive patients carrying the T allele may be at increased risk of cardiovascular events.

The longitudinal haemodynamic force (LF) acting on a bifurcated stent graft for abdominal aortic aneurysm repair has been estimated previously using a simple one-dimensional analytical model based on the momentum equation which assumes steady flow of an inviscid fluid. Using an instrumented stent-graft model an experimental technique was developed to measure the LF under pulsatile flow conditions. The physical stent-graft model, with main trunk diameter of 30mm and limb diameters of 12 mm, was fabricated from aluminium. Strain gauges were bonded on to the main trunk to determine the longitudinal strain which is related to the LF. After calibration, the model was placed in a pulsatile flow system with 40 per cent aqueous glycerol solution as the circulating fluid. The LF was determined using a Wheatstone bridge signal-conditioning circuit. The signals were averaged over 590 cardiac cycles and saved to a personal computer for subsequent processing. The LF was strongly dependent on the pressure but less so on the flowrate. The measured forces were higher than those predicted by the simplified mathematical model by about 6-18 per cent during the cardiac cycle. The excess measured forces are due to the viscous drag and the effect of pulsatile flow. The peak measured LF in this model of 30 mm diameter may exceed the fixation force of some current clinical endovascular stent grafts.

Improvement in fixation strength was noted with increasing stent-graft oversizing of up to 20%. Fenestrated stent-grafts offer higher ultimate fixation compared to standard devices. However, the ultimate fixation strength was not recruited until an initial phase of short migration occurred as the barbs engaged. While this movement is inconsequential with standard stent-grafts, it has the potential to crush the stents placed into aortic side branches with fenestrated endografts.

Improvement in fixation strength was noted with increasing stent-graft oversizing of up to 20%. Fenestrated stent-grafts offer higher ultimate fixation compared to standard devices. However, the ultimate fixation strength was not recruited until an initial phase of short migration occurred as the barbs engaged. While this movement is inconsequential with standard stent-grafts, it has the potential to crush the stents placed into aortic side branches with fenestrated endografts.