Detection of coronary microembolisation by Doppler ultrasound during percutaneous coronary interventions

Abstract

Objective: To validate an intracoronary Doppler ultrasound device for high intensity transient signals (HITS) detection and to assess the incidence of HITS during percutaneous coronary intervention (PCI). Methods and Results:In an in vitro model, particle count and number of HITS detected by an intracoronary 0.014 inch Doppler wire were closely correlated (r = 0.97, p , 0.001). In the clinical study, 32 patients (mean (SD) age 61 (11) years; 23 men, nine women) with coronary artery disease were treated with balloon dilatation and stent implantation for a single vessel stenosis. In these patients HITS were detected during PCI in 84% (27 of 32). Reproducibility (r = 0.99, p , 0.001) and interobserver agreement (r = 0.84, p , 0.001) of HITS counts were significant. The number of HITS after stent implantation was significantly higher than after balloon dilatation (11 (7) v 2 (4), p , 0.001). Postprocedural coronary flow velocity reserve (CFVR) was , 2.0 in 55% (16 of 29) of all patients after balloon dilatation and , 2.0 in 23% (six of 26) after stent implantation. The number of HITS after stent implantation did not differ significantly between patients with CFVR , 2.0 and patients with CFVR > 2.0 (12 (8) v 10 (7), not significant). Conclusions: Embolic particles can be detected as HITS by an intracoronary Doppler ultrasound device. Coronary microembolism is often observed during PCI, especially after stent implantation. However, the incidence of HITS alone does not explain a reduced CFVR after PCI.

Detection of Coronary Microembolization by Doppler Ultrasound in Patients With Stable Angina Pectoris Undergoing Elective Percutaneous Coronary Interventions

“…9 In the present study, the frequency of coronary microemboli was higher because we included 2 more procedural phases. We also counted microemboli during balloon or stent advancement over the guidewire and after dilation.…”

“…In the present experimental setting for simulation of PCI, we did not find air microbubbles after repeated balloon deflations that might be generated by excavations. 9 However, contrast injections generate air microbubbles. Therefore, we excluded the phase of contrast injections in the present analysis, which may occlude the coronary microcirculation only for a short time.…”

“…In a previous study, 9 we reported that an intracoronary Doppler guidewire is a feasible device for real-time detection and quantification of microembolism during PCI. Coronary microembolism often occurred immediately after balloon deflation, especially after stent deployment.…”

“…The observed intraobserver (Rϭ0.99, PϽ0.001) and interobserver (Rϭ0.84, PϽ0.001) agreement in a prior study suggested a good reproducibility for intracoronary Doppler-derived quantification of microemboli. 9 By convention, 1 second of microembolic shower signals was considered 10 microemboli. 16 All microemboli recorded during contrast injections were excluded from the analysis because they may indicate microbubbles, which may be less hazardous than solid particles in the coronary circulation.…”

“…The principles of detection of microemboli with multifrequency Doppler have been described previously. 9 A 0.014-inch Doppler guidewire with a 12-MHz pulsed Doppler transducer was connected to a console (FloMap System, Volcano Therapeutics). The system insonated at a depth of 5.2 mm and used a 128-point fast Fourier transform for signal-intensity measurement.…”