CORP: Ultrasound assessment of vascular function with the passive leg movement technique

Abstract

As dysfunction of the vascular system is an early, modifiable step in the progression of many cardiovascular diseases, there is demand for methods to monitor the health of the vascular system noninvasively in clinical and research settings. Validated by very good agreement with more technical assessments of vascular function, like intra-arterial drug infusions and flow-mediated dilation, the passive leg movement (PLM) technique has emerged as a powerful, yet relatively simple, test of peripheral vascular function. In the PLM technique, the change in leg blood flow elicited by the passive movement of the leg through a 90° range of motion is quantified with Doppler ultrasound. This relatively easy-to-learn test has proven to be ≤80% dependent on nitric oxide bioavailability and is especially adept at determining peripheral vascular function across the spectrum of cardiovascular health. Indeed, multiple reports have documented that individuals with decreased cardiovascular health such as the elderly and those with heart failure tend to exhibit a substantially blunted PLM-induced hyperemic response (~50 and ~85% reduction, respectively) compared with populations with good cardiovascular health such as young individuals. As specific guidelines have not yet been put forth, the purpose of this Cores of Reproducibility in Physiology (CORP) article is to provide a comprehensive reference for the assessment and interpretation of vascular function with PLM with the aim to increase reproducibility and consistency among studies and facilitate the use of PLM as a research tool with clinical relevance.

The passive leg movement technique for assessing vascular function: defining the distribution of blood flow and the impact of occluding the lower leg

“…Vascular function can be defined as the capacity of the vascular system to adjust tone appropriately in response to a given stimulus (Gifford & Richardson, ). With both ageing and disease, there is evidence of vascular dysfunction, typically linked to the endothelium and the attenuated bioavailability of the antiatherogenic, antithrombotic and vasodilatory factor nitric oxide (NO) (Deanfield, Halcox, & Rabelink, ; Gifford & Richardson, ; Groot et al., ; Seals, Jablonski, & Donato, ).…”

“…Vascular function can be defined as the capacity of the vascular system to adjust tone appropriately in response to a given stimulus (Gifford & Richardson, ). With both ageing and disease, there is evidence of vascular dysfunction, typically linked to the endothelium and the attenuated bioavailability of the antiatherogenic, antithrombotic and vasodilatory factor nitric oxide (NO) (Deanfield, Halcox, & Rabelink, ; Gifford & Richardson, ; Groot et al., ; Seals, Jablonski, & Donato, ). As vascular endothelial dysfunction has been documented to be antecedent to cardiovascular disease, it is imperative to have an accurate and reliable tool to assess vascular function, in both the research and the clinical setting (Deanfield et al., ; Gokce et al., ; Heitzer, Schlinzig, Krohn, Meinertz, & Munzel, ; Lind, Berglund, Larsson, & Sundstrom, ; Seals et al., ; Widlansky, Gokce, Keaney, & Vita, ).…”

“…The assessment of passive leg movement (PLM)‐induced hyperaemia and vasodilatation has recently been recognized as a novel, non‐invasive technique to evaluate vascular function. This technique has clinical promise as it is able to distinguish differences in vascular function across the spectrum of cardiovascular health and disease (Gifford & Richardson, ; Iepsen et al., ; Trinity et al., ; Witman et al., ).…”

“…Employing the PLM approach, as described by recent guidelines (Gifford & Richardson, ), the participant sits in a chair while their common femoral artery (CFA) is scanned with Doppler ultrasound and their leg is passively moved through a 90 deg range of motion at the knee at a rate of 1 Hz. It is presumed that, due to the passive movement of the leg and the subsequent stretch of the thigh muscles, there is mechanical deformation of the blood vessels which initiates the local release of vasodilators, such as NO (Cheng et al., ; Jufri, Mohamedali, Avolio, & Baker, ).…”

“…It is presumed that, due to the passive movement of the leg and the subsequent stretch of the thigh muscles, there is mechanical deformation of the blood vessels which initiates the local release of vasodilators, such as NO (Cheng et al., ; Jufri, Mohamedali, Avolio, & Baker, ). As a result of this movement, within the first 30 s there is an initial rapid increase in blood flow (BF) and vascular conductance (VC) that gradually returns to near baseline values (Gifford & Richardson, ; Trinity et al., ). This movement‐induced hyperaemic response, as measured by the area under the curve (AUC), is up to 80% nitric oxide mediated in healthy humans (Mortensen, Askew, Walker, Nyberg, & Hellsten, ; Trinity et al., ).…”