Diastolic-systolic velocity ratio to detect coronary stenoses under physiological resting conditions: a mechanistic study

Figures

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  Figure 1. Examples of two patients included in the study. Shown are the Doppler flow velocity measurements during resting conditions (Panel A), the coronary angiogram (Panel B) and the pressure tracing during hyperaemic conditions after injection of 150 μg of adenosine (Panel C). DSVR, diastolic-systolic velocity ratio; FFR, fractional flow reserve; LAD, left anterior descending artery.

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  Figure 2. Invasive diastolic-systolic velocity ratio according to fractional flow reserve classification in cohort 1. Bars represent mean and error bars represent SEM.

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  Figure 3. Diagnostic performance of invasive DSVR in cohort 1. Receiver operating characteristic curves for DSVR in the left anterior descending artery branches to predict FFR at its ischaemic threshold of 0.75. DSVR, diastolic-systolic velocity ratio; FFR, fractional flow reserve.

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  Figure 4. Relationship between invasive phasic flow and resistance in cohort 1. Panel A shows a strong inverse relationship between diastolic flow velocity and diastolic vascular resistance. Panel B shows similar results for systole. Panel C demonstrates a strong inverse relationship between DSVR and the ratio between diastolic and systolic vascular resistance. DSVR, diastolic-systolic velocity ratio.

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  Figure 5. Invasive resistance distribution according to functional stenosis severity in cohort 1. Panel A shows the distribution of microvascular resistance stratified according to diastole (open bars) and systole (marked bars) classified by FFR. Panel B shows the distribution of stenosis resistance stratified according to diastole (open bars) and systole (marked bars) classified by FFR. Panel C shows the total resistance per FFR group stratified according to systole and diastole by integrating microvascular (red bars) and stenosis resistance (blue bars). Panel D shows the stenosis resistance as a percentage of the total vascular resistance composed of both stenosis and microvascular resistance for both diastole (open bars) and systole (marked bars). Panel E shows the difference between the diastolic and systolic percentage stenosis resistance of total resistance. As FFR group worsens, the stenosis resistance constitutes a comparatively greater portion of total resistance for diastole than for systole. Finally, panel F shows that the ratio between diastolic and systolic vascular resistance increases as FFR worsens. Bars represent mean and error bars represent SEM. *Indicates p is…

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  Figure 6. Summary of the DSVR rationale. This figure illustrates the shift in resting resistance distributions during diastole and systole averaged for the group of unobstructed LAD branches with FFR >0.95 and DSVR of 2.1 (A) and averaged for the group with obstructed LAD branches with FFR <0.65 and DSVR of 1.5 (B). Because stenosis resistance (blue area in the pie charts) is negligible in unobstructed LAD branches, its contribution to total vascular resistance is low during both diastole and systole (both 1%). In LAD branches with stenosis, the stenosis resistance represents 47% of total vascular resistance during diastole when the microvasculature is open and microvascular resistance is low (red area in the pie charts). During systole, however, the microvasculature is compressed by the contracting myocardium resulting in high microvascular resistance. Because stenosis resistance does not appreciably differ during diastole and systole, the stenosis resistance has a much smaller impact during systole and only represents 23% of total vascular resistance. As such, in stenosis the diastolic-systolic resistance ratio is increased compared with unobstructed vessels. DSVR, diastolic-systolic…

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  Figure 7. Correlation between invasive and non-invasively measured DSVR in cohort 2. This figure shows DSVR measured both invasively and non-invasively by transthoracic echocardiography within the same patient from the separate cohort. DSVR, diastolic-systolic velocity ratio.