P4.12 a Comparison of Different Methods to Determine Aortic Pulse Wave Velocity in Aneurysmatic and Control Mice

Accurate determination of aortic pulse wave velocity (PWV) in mice is not straightforward, due to the high resolution needed in both time and space. We compared different techniques in control and aneurysmatic mice. NZ30 male, 18 weeks-old C57Bl/6 mice were included. NZ20 animals got implanted an osmotic pump delivering Angiotensin II, and were injected anti-TGF-beta antibodies to provoke aneurysm formation. PWV was determined using 4 different methods: (i) global foot-to-foot transit time based on ultrasound pulsed Doppler velocities (VisualSonics Vevo 2100) at the ascending aorta and 4 cm distal to it (tape-measured); (ii) abdominal foot-to-foot transit time based on 2 invasive pressure sensors placed exactly 2 cm apart (Sciscense catheter), considered the gold standard; (iii) abdominal, in vivo, invasive pressure-diameter (P-D) waveforms obtained via RF wall tracking; (iv) abdominal, ex-vivo P-D curves measured at in vivo stretch using an in-house myograph. The latter were restricted to the in vivo measured pressure range. P-D data were converted to PWV using the Bramwell-Hill equation and groups were statistically compared via a paired student-test. 13 complete datasets were available for analysis. In the control animals all in vivo methods yielded significantly different PWVs compared to the gold standard (p<0.05), and none of the investigated methods were found to correlate to each other. Moreover aneurysm presence was not picked up by transit-time methods, while it resulted in a significant increase in PWV (p<0.0001) in both P-D methods. PWV measurement in mice is not straightforward and results should be interpreted carefully.