Abstract
Purpose :
Though early detection of aortic stenosis (AS) can improve the survival rate, conventional methods such as stethoscope and echocardiography, the gold standard of evaluating condition of AS, are subjective and technique-sensitive.We developed Doppler optical coherence tomography flowmeter (DOCT flowmeter: IOVS 2016, IOVS 2017, PLoS ONE 2018) which can easily, accurately and non-invasively measure retinal blood flow (RBF) within 3 seconds. We also reported that DOCT flowmeter showed the abnormal velocity waveform of retinal blood flow (RBF) in a patient with aortic regurgitation. The purpose of the study was to investigate the relationship between parameters of DOCT flowmeter and echocardiography in patients with AS.
Methods :
Eleven eyes of 11 subjects who visited the cardiovascular surgery clinic in Asahikawa Medical University hospital and was diagnosed with AS, and 20 eyes of 20 age-matched healthy subjects (control) were chosen in this study. The superotemporal artery in randomly selected one eye was used for measuring RBF using DOCT flowmeter. The upstroke time (UT) of the RBF velocity waveforms, an index representing a rising feature value of RBF velocity waveforms, was calculated. The peak velocity (PV) was measured by echocardiography, then the correlation coefficient between UT and PV was calculated. In addition, in 9 out of 11 AS patients, RBF was measured before and after the aortic valve replacement surgery to check if UT was improved after the surgery. Pearson’s correlation coefficient was used to assess the relationships between UT and PV. Paired t test was employed to compare UTs between before and after the surgery for AS. P values less than 0.05 were considered statistically significant.
Results :
UT in AS patients (0.22 ± 0.017 sec) was longer than that in control (0.14 ± 0.022 sec) (P < 0.001). There was a very high correlation between UT and PV (R = 0.91) (P < 0.001). After the surgery for AS, UT was significantly improved (pre-op, 0.22 ± 0.019 sec; post-op, 0.14 ± 0.019 sec) (p < 0.001).
Conclusions :
Current study strongly suggests that DOCT is equivalent to conventional echography in detecting blood flow changes occurring in AS patients. Since DOCT flowmeter can non-invasively acquire the RBF velocity waveforms within 3 seconds, this modality is a useful and convenient screening test that can potentially replace the conventional echography.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.