Reactive hyperemia: a review of methods, mechanisms, and considerations

Abstract

Reactive hyperemia is a well-established technique for noninvasive assessment of peripheral microvascular function and a predictor of all-cause and cardiovascular morbidity and mortality. In its simplest form, reactive hyperemia represents the magnitude of limb reperfusion following a brief period of ischemia induced by arterial occlusion. Over the past two decades, investigators have employed a variety of methods, including brachial artery velocity by Doppler ultrasound, tissue reperfusion by near-infrared spectroscopy, limb distension by venous occlusion plethysmography, and peripheral artery tonometry, to measure reactive hyperemia. Regardless of the technique used to measure reactive hyperemia, blunted reactive hyperemia is believed to reflect impaired microvascular function. With the advent of several technological advancements, together with an increased interest in the microcirculation, reactive hyperemia is becoming more common as a research tool and is widely used across multiple disciplines. With this in mind, we sought to review the various methodologies commonly used to assess reactive hyperemia and current mechanistic pathways believed to contribute to reactive hyperemia and reflect on several methodological considerations.

Acute reductions in haematocrit increase flow‐mediated dilatation independent of resting nitric oxide bioavailability in humans

“…mL min −1 ) (Limberg et al . 2020; Rosenberry & Nelson, 2020). Antegrade and retrograde shear stress were calculated as shear stress in the forward (positive) and backward (negative) direction, respectively, and mean shear stress as the sum of antegrade and retrograde (time‐averaged mean shear stress).…”

Suitability of the muscle O2 resaturation parameters most used for assessing reactive hyperemia: a near-infrared spectroscopy study

“… 1 , 2 Assessment of reactive hyperemia in microcirculation has been used as a measure of microvascular function. 3 Microvascular dysfunction may lead to rarefaction of downstream vessels and consequent reduction in the number of capillaries, contributing to hypertension and cardiovascular events. 4 Moreover, downstream arterial disease may reduce muscle blood supply, leading to fatigue, cramp, discomfort, or pain in limbs during daily activities.…”

Estimation of skin microcirculatory hemoglobin oxygen saturation and red blood cell tissue fraction using a multispectral snapshot imaging system: a validation study

“…Stimulus-response protocols reveal the microcirculatory system's ability to constrict or dilate vessels and thereby regulate the blood flow to adapt to periods of ischemia or heating provocation. [2][3][4][5] Oxy-and deoxyhemoglobin, found in RBCs, are strong absorbers in the visible wavelength range in human tissue with unique spectral fingerprints. The amount of oxy-and deoxyhemoglobin may be estimated using diffuse reflectance spectroscopy (DRS) to study hemoglobin oxygen saturation and RBC tissue fraction.…”

“…Stimulus–response protocols reveal the microcirculatory system’s ability to constrict or dilate vessels and thereby regulate the blood flow to adapt to periods of ischemia or heating provocation. 2 – 5 …”