The 2020 SVM/SVU Consensus Statement for the Interpretation of Peripheral Arterial and Venous Doppler Waveforms: An interview with SVM members of the Writing Committee

The first multisocietal, consensus-based nomenclature for arterial and venous Doppler waveforms was published online on July 15, 2020 in Vascular Medicine and the Journal for Vascular Ultrasound.^1,2 This publication reflects a multispecialty collaboration in partnership with the Society for Vascular Medicine (SVM) and the Society for Vascular Ultrasound (SVU), with Writing Committee members nominated by both organizations. This document addresses a significant area of confusion in vascular testing. To update SVM members on this consensus statement, Drs Daniella Kadian-Dodov and Ehrin Armstrong, co-chairs of the SVM Publications and Communications Committee, interviewed Drs Esther Kim and Aditya Sharma, co-chairs of the Writing Committee for the consensus.

How does this consensus statement strengthen Doppler waveform nomenclature in arterial and venous disease?

Duplex ultrasound is the principal tool for diagnosis and monitoring of several vascular conditions. However, there is considerable variation in describing, reporting, and interpretation of waveforms between vascular sonographers as well as interpreting physicians. In 2015, Scissons et al. published a survey of 2000 ultrasound professionals, which stated that one-fifth of the respondents reported one or more occurrences of repeat arterial Doppler examinations because of a lack of understanding of the terminology used to describe Doppler waveforms. ³ The discrepancies are very deep rooted as even authoritative publications in the field of vascular disease have published varying and inconsistent characterization of Doppler waveforms, particularly arterial waveforms. ⁴ The 2020 consensus statement provides the first ever multisocietal and multidisciplinary response to develop a standardized, methodical approach to the interpretation of both arterial and venous Doppler waveforms.^1,2 The statement clarifies and standardizes nomenclature by describing all arterial and venous waveforms using key descriptors and modifiers. The Writing Committee recognizes that ‘garbage in’ is ‘garbage out’, meaning that a waveform can only be described if it is of adequate quality. Thus, we made sure to include Doppler transducer optimization techniques to enhance the quality and presentation of Doppler spectral waveform and color Doppler data. It also provides guidance for applying waveform descriptors and modifiers in the sonographer’s report and the physician’s final interpretation. It is vital to note that descriptors and modifiers are terms used to describe a waveform and whether a waveform is ‘normal’ or ‘abnormal’ is an interpretation that requires knowledge of the vascular bed involved and the presence of physiologic or pathologic changes related to the clinical situation. Copious examples of changes seen in the waveform with various pathologic or physiologic changes are described in detail by way of 18 tables and 62 figures.

Historically there has been significant confusion and variability in the use of waveform terms triphasic, biphasic, and monophasic. How does this statement clarify ‘phasicity’?

The term ‘biphasic’, in particular, has sowed confusion amongst ultrasound practitioners. To simplify the nomenclature, the Writing Committee felt it was necessary first to define the reference baseline. Thus, the consensus was to define a zero-flow baseline as the reference baseline for all spectral Doppler waveforms and move away from the terms triphasic and biphasic.^1,2 According to the new nomenclature, any waveform that crosses the zero baseline is termed ‘multiphasic’, and any waveform that does not cross the zero-flow baseline is ‘monophasic’. In reference to the term ‘biphasic’, there are now clarifying terms that can be used. For instance, a waveform previously called ‘biphasic’ is now better described as a multiphasic high resistive (has a sharp peak and goes above and below baseline) or a monophasic waveform of intermediate resistance (sharp upstroke with end systolic notch and continuous flow during diastole). These examples provide a more specific and descriptive hemodynamic analysis, which previously would have been grouped under a non-descript heading.

What are the key definitions and descriptors that are inherent to the analysis of arterial waveforms? How do these differ from the past convention?

The major descriptors are flow direction, phasicity, and resistance. Flow direction is described as antegrade, retrograde, bidirectional, and absent. Resistance is described as high, intermediate, and low resistance. In addition to these major descriptors, several modifier terms can also be used to further describe a waveform if needed. These include upstroke (rapid or prolonged), sharp peak, spectral broadening, staccato, dampened, and flow reversal. The definitions of these terms are provided in great detail with images as examples in the consensus document.^1,2 The goal of the consensus document was not to develop a new nomenclature but to clarify and organize existing descriptors so that we could start to ‘speak the same language’. For example, previous alternate terms such as parvus et tardus, attenuated, and blunted are now consolidated under the modifier term ‘dampened’.

What are the key definitions and descriptors that are inherent to the analysis of venous waveforms? How do these differ from past convention?

The major descriptors are flow direction, flow pattern, and spontaneity. The description of flow direction is similar to the arterial waveform description. The flow pattern is unique for venous waveforms and described as respirophasic, pulsatile, continuous, and regurgitant. The descriptor spontaneity describes a waveform as either spontaneous or nonspontaneous. Modifiers include terms organized under the terms augmentation, reflux, and fistula flow. In the past, there was no convention for describing venous waveforms. Some practitioners would sometimes even use arterial descriptors as biphasic to describe highly pulsatile waveforms, or monophasic for highly continuous waveforms. Our hope is that the proposed nomenclature will improve communication when discussing venous waveforms as well.

What are the key clinical takeaway points from this document for vascular medicine specialists?

• The primary focus of this effort was to improve communication. The development of this consensus document is a major step towards clarifying and standardizing the key definitions of descriptors and modifiers inherent to the analysis of arterial and venous Doppler waveforms.

• The document was a multidisciplinary effort, including sonographers and physicians from various specialties, so we hope that the adoption of the nomenclature will be broad.

• We recognize that widespread adoption of the nomenclature may take some time, but we hope it takes us one step closer to ‘speaking the same language’, so that our communication improves and ultimately improves patient care.