Objective Diastolic-systolic velocity ratio (DSVR) is a resting index to assess stenoses in the left anterior descending artery (LAD). DSVR can be measured by echocardiographic or intracoronary Doppler flow velocity. The objective of this cohort study was to elucidate the fundamental rationale underlying the decreased DSVR in coronary stenoses.
Methods In cohort 1, simultaneous measurements of intracoronary Doppler flow velocity and pressure were acquired in the LAD of 228 stable patients. Phasic stenosis resistance, microvascular resistance and total vascular resistance (defined as stenosis and microvascular resistance combined) were studied during physiological resting conditions. Stenoses were classified according to severity by strata of 0.10 fractional flow reserve (FFR) units.
Results DSVR was decreased in stenoses with lower FFR. Stenosis resistance was equal in systole and diastole for every FFR stratum. Microvascular resistance was consistently higher during systole than diastole. In lower FFR strata, stenosis resistance as a percentage of the total vascular resistance increases both during systole and diastole. The difference between the stenosis resistance as a percentage of total vascular resistance during systole and diastole increases for lower FFR strata, with an accompanying rise in diastolic-systolic resistance ratio. A significant inverse correlation was observed between DSVR and the diastolic-systolic resistance ratio (r=0.91, p<0.001). In cohort 2 (n=23), DSVR was measured both invasively and non-invasively by transthoracic echocardiography, yielding a good correlation (r=0.82, p<0.001).
Conclusions The rationale by which DSVR is decreased distal to coronary stenoses is dependent on a comparatively higher influence of the increased stenosis resistance on total vascular resistance during diastole than systole.
- stable angina
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Contributors GdW, CB, RP, SSN, TPvdH, ME-P, SS, MM, PK, JE, JJP, NvR and JD were involved in data collection. GdW designed the study, performed data and statistical analysis, and drafted the manuscript. NvR and JD supervised the project. All authors made critical revisions to key intellectual content of the manuscript.
Funding A fellowship grant awarded to GdW by the ICIN Netherlands Heart Institute helped fund the present study.
Competing interests JD is codeveloper of intellectual property, which is licensed to Philips Volcano by Imperial College London. He receives consultancy and research funding from Philips Volcano. CC, RP, SSN, JJP, TPvdH, NVR and JE report receiving fees for speaking at educational events organised by Philips Volcano. The other authors report no conflict of interest.
Patient consent for publication Obtained.
Ethics approval The different study protocols were approved by the respective institutional review committees and complied with the principles of the Declaration of Helsinki.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
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