Submitted on October 8, 2007
Revised on December 22, 2008
Accepted on January 9, 2009
Stress phase-angle depicts differences in coronary artery hemodynamics due to changes in flow and geometry after percutaneous coronary intervention
Ryo Torii1*, Nigel B Wood1, Nearchos Hadjiloizou1, Andrew W Dowsey1, Andrew Wright2, Alun D Hughes1, Justin Davies3, Darrel P Francis4, Jamil Mayet5, Guang-Zhong Yang1, Simon AMcG Thom, and Xiao Yun Xu1
1 Imperial College London
2 St. Mary's Hospital and Imperial College London
3 St. Mary's Hosp., London, UK
4 Imperial College
5 International Centre for Circulatory Health
* To whom correspondence should be addressed. E-mail: r.torii{at}imperial.ac.uk.
The effects of changes in flow velocity waveform and arterial geometry before and after percutaneous coronary intervention (PCI) in a right coronary artery (RCA) were investigated using computational fluid dynamics. An RCA from a patient with a stenosis was reconstructed based on multislice CT images. A non-stenosed model, simulating the same RCA after PCI, was also constructed. Blood flows in the RCA models were simulated using pulsatile flow waveforms acquired with an intravascular ultrasound Doppler probe in the RCA of a patient undergoing PCI. It was found that differences in the waveforms before and after PCI did not affect time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI), but the phase-angle between pressure and wall shear stress on the endothelium (stress phase-angle: SPA), differed markedly. The median SPA was -63.9 deg (range -204 to -10.0 deg) for pre-PCI state whereas it was 10.4 deg (range -71.1 to 25.4 deg) in the post-PCI state; i.e. more asynchronous in the pre-PCI state. SPA has been reported to influence secretion of vasoactive molecules (e.g. NO, PGI2 and ET-1) and asynchronous SPA (
-180 deg) is proposed to be pro-atherogenic. Our results suggest that differences in pulsatile flow waveform may have an important influence on atherogenesis, although associated with only minor changes in TAWSS and OSI. SPA may be a useful indicator in predicting sites prone to atherosclerosis.
