Abstract
Wave intensity analysis (WIA) is a technique developed from the field of gas dynamics that is now being applied to assess cardiovascular physiology. It allows quantification of the forces acting to alter flow and pressure within a fluid system, and as such it is highly insightful in ascribing cause to dynamic blood pressure or velocity changes.When co-incident waves arrive at the same spatial location they exert either counteracting or summative effects on flow and pressure. WIA however allows waves of different origins to be measured uninfluenced by other simultaneously arriving waves. It therefore has found particular applicability within the coronary circulation where both proximal (aortic) and distal (myocardial) ends of the coronary artery can markedly influence blood flow. Using these concepts, a repeating pattern of 6 waves has been consistently identified within the coronary arteries, 3 originating proximally and 3 distally. Each has been associated with a particular part of the cardiac cycle.The most clinically relevant wave to date is the backward decompression wave, which causes the marked increase in coronary flow velocity observed at the start of the diastole. It has been proposed that this wave is generated by the elastic re-expansion of the intra-myocardial blood vessels that are compressed during systolic contraction. Particularly by quantifying this wave, WIA has been used to provide mechanistic and prognostic insight into a number of conditions including aortic stenosis, left ventricular hypertrophy, coronary artery disease and heart failure. It has proven itself to be highly sensitive and as such a number of novel research directions are encouraged where further insights would be beneficial.
Highlights
Wave intensity analysis (WIA) is a technique that has emerged from the field of gas dynamics and is proving useful in the assessment of coronary physiology
The two waves which dominate in terms of magnitude are the forward compression wave (FCW) and the backward decompression wave (BDW) - both cause an accelerative force on blood flow but with differing results on actual velocity due to the presence or absence of opposing intra-myocardial pressure
Wave intensity analysis has emerged as a powerful tool to investigate the coronary system
Summary
Wave intensity analysis (WIA) is a technique that has emerged from the field of gas dynamics and is proving useful in the assessment of coronary physiology. Since our decomposition of the measured waveforms into successive incremental wavefronts assumed that the wavefronts are additive and only forward and backward waves are present, at any point at any time in the artery dP = dP+ + dP− dU = dU+ + dU−. These equations and the water hammer equations give us 4 equations for the 4 unknowns, dP+, dP−, dU+ and dU−, in terms of the known changes in pressure and velocity, dP and dU. The wave energy fraction can be useful to differentiate, for example, between changes due to a particular mechanism and changes due to an overall change of heart function
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
