Abstract
Background: Wave speed is needed to separate net wave intensity into forward and backward traveling components. However, wave speed in diseased coronary arteries cannot be assessed from hemodynamic measurements obtained distal to a stenosis. Wave speed inherently depends on arterial wall properties which should be similar proximal and distal to a stenosis. Our hypothesis is that proximal wave speed can be used to separate net wave intensity obtained distal to a stenosis.Methods: We assessed coronary wave speed using the sum-of-squares single-point technique (SPc) based on simultaneous intracoronary pressure and flow velocity measurements in human coronary arteries. SPc at resting flow was determined in diseased coronary vessels of 12 patients both proximal and distal to the stenosis. In seven of these vessels, distal measurements were additionally obtained after revascularization by stent placement. SPc was also assessed at two axial locations in 14 reference vessels without a stenosis.Results: (1) No difference in SPc was present between proximal and distal locations in the reference vessels. (2) In diseased vessels with a focal stenosis, SPc at the distal location was paradoxically larger than SPc proximal to the stenosis (28.4 ± 3.7 m/s vs. 18.3 ± 1.8 m/s, p < 0.02), despite the lower distending pressure downstream of the stenosis. The corresponding separated wave energy tended to be underestimated when derived from SPc at the distal compared with the proximal location. (3) After successful revascularization, SPc at the distal location no longer differed from SPc at the proximal location prior to revascularization (21.9 ± 2.0 m/s vs. 20.8 ± 1.9 m/s, p = 0.48). Accordingly, no significant difference in separated wave energy was observed for forward or backward waves.Conclusion: In diseased coronary vessels, SPc assessed from distal hemodynamic signals is erroneously elevated. Our findings suggest that proximal wave speed can be used to separate wave intensity profiles obtained downstream of a stenosis. This approach may extend the application of wave intensity analysis to diseased coronary vessels.
Highlights
Wave intensity analysis has emerged as a powerful timedomain method to investigate the dynamic interactions between the contracting myocardium and coronary blood flow
The dataset for this study was extracted from existing hemodynamic recordings obtained in patients with stable angina pectoris and a single stenosis in a coronary artery, who were scheduled for elective percutaneous coronary intervention (PCI)
Simultaneous pressure and flow velocity signals of sufficient quality at rest conditions were collected in 12 patients both upstream and downstream of the stenosis
Summary
Wave intensity analysis has emerged as a powerful timedomain method to investigate the dynamic interactions between the contracting myocardium and coronary blood flow. Wave speed is fundamental to split net wave intensity into separate forward and backward traveling components [4]. Local coronary wave speed in normal coronary vessels can be assessed from simultaneously acquired pressure and flow velocity signals [5]. The validity of this approach, turned out to be compromised under conditions that frequently occur in the clinical setting, such as hyperemia by microvascular dilation or downstream of a stenosis in diseased coronary vessels [6,7,8]. Wave speed in diseased coronary arteries cannot be assessed from hemodynamic measurements obtained distal to a stenosis. Our hypothesis is that proximal wave speed can be used to separate net wave intensity obtained distal to a stenosis
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