Arterial Blood-Flow Acceleration Time on Doppler Ultrasound Waveforms: What Are We Talking About?

Abstract

In recent years, the assessment of systolic acceleration in lower-extremity peripheral artery disease (PAD) has been brought back into the spotlight, whatever measure is used: time (in s) or acceleration (in cm.s−2). Acceleration time (also called systolic rise time) and maximal acceleration are two different but very useful measurements of growing interest in PAD. A background of the historical development, physics rationale, semantics, and methods of measurement, as well as their strengths and weaknesses, are discussed herein. Acceleration time is a powerful tool for predicting significant arterial stenosis or for estimating the overall impact of PAD as it is highly correlated to the ankle or toe pressure indexes. It could even become a new diagnostic criterion for critical limb ischemia. Similarly, maximal systolic acceleration ratios are highly predictive of carotid or renal stenosis. However, the literature lacks reference standards or guidelines for the assessment of such variables, and their measurement techniques seem to differ between authors. We propose herein a semantic and measurement statement order to clarify and help standardize future research.

Accuracy of maximal acceleration time of pedal arteries to diagnose critical limb-threatening ischemia

“…In this respect, it is essential that any practitioner adheres to measurement standards or guidelines of either AT or maximal acceleration. 18 Our results show that AT max has an excellent intra-observer reproducibility. In Figure 4, we can see that the agreement between two AT max measurements is very high, especially when AT is below 215 ms. On the other hand, AT max shows greater variability when the value exceeds 215 ms emphasizing the need for a mean value between at least two measurements.…”

“…AT (in ms) was measured after determining manually the start of the systolic uprise (when the acceleration, in cm/s −2 , becomes positive) to the top of the systolic peak (when the acceleration returns to zero) (Figure 1). 18 Every study physician measured AT on two distinct systolic peaks belonging to the same DW recording. For each artery (DPA and LPA), the value of AT retained was as the mean of the two measurements.…”

The Role of Ultrasound Examination in the Assessment of Suitability of Calcified Arteries for Vascular Access Creation—Mini Review

“…The advantage of RI over absolute velocities is that it is less susceptible to measurement error as it is less dependent on the Doppler angle [ 34 ]. The acceleration during early systole is described by acceleration time (AT), i.e., the time difference between the onset of systolic upstroke and the top of the first systolic peak [ 35 , 36 ]. To avoid problems with different curve shapes, the maximal systolic acceleration (Acc max ) can be measured as the steepest part of the systolic upslope, i.e., from the beginning of systole to the point of break in systolic upstroke (i.e., the point at which a change in slope is clearly evident) [ 35 , 36 ].…”

“…The acceleration during early systole is described by acceleration time (AT), i.e., the time difference between the onset of systolic upstroke and the top of the first systolic peak [ 35 , 36 ]. To avoid problems with different curve shapes, the maximal systolic acceleration (Acc max ) can be measured as the steepest part of the systolic upslope, i.e., from the beginning of systole to the point of break in systolic upstroke (i.e., the point at which a change in slope is clearly evident) [ 35 , 36 ]. Some of these parameters, which are routinely used to assess renal artery stenosis, may also be useful in assessing the inflow provided by the feeding artery for future AVF.…”

“…AT is dependent on the PSV, therefore different cut-off values can be expected in different vascular beds (e.g., a 70 ms cut-off is used for intrarenal Doppler, while 120 and 215 ms cut-offs were suggested for the femoral artery [ 43 , 44 ]). Acc max may be more comparable between different vascular beds, although its measurement requires an optimal insonation angle, while AT measurements are not dependent on the insonation angle [ 36 ]. There are no data in the literature on AT in the context of vascular access, but AT, Acc max and AI should definitely be explored in this context in the future, although significant proximal stenosis in the upper extremity is quite rare.…”