Microvascular Dysfunction in Peripheral Artery Disease: Is Heat Therapy a Viable Treatment?

Abstract

Peripheral artery disease (PAD) is characterized by the development of atherosclerotic plaques in the lower-body conduit arteries. PAD is commonly accompanied by microvascular disease, which may result in poor wound healing, plantar ulcer development, and subsequent limb amputation. Understanding the mechanisms underlying the development of plantar ulcers is a critical step in the development of adequate treatment options for patients with PAD. Skin is classified into two major components: glabrous and non-glabrous. These skin types have unique microcirculation characteristics, making it important to differentiate between the two when investigating mechanisms for plantar ulcer development in PAD. There is evidence for a microcirculation compensatory mechanism in PAD. This is evident by the maintenance of basal microcirculation perfusion and capillary filling pressure despite a reduced pressure differential beyond an occlusion in non-critical limb ischemia PAD. The major mechanism for this compensatory system seems to be progressive vasodilation of the arterial network below an occlusion. Recently, heat therapies have emerged as novel treatment options for attenuating the progression of PAD. Heat therapies are capable of stimulating the cardiovascular system, which may lead to beneficial adaptations that may ultimately reduce fatigue during walking in PAD. Early work in this area has shown that full-body heating is capable of generating an acute cardiovascular response, similar to exercise, which has been suggested as the most efficient treatment modality and may generate adaptations with chronic exposure. Heat therapies may emerge as a conservative treatment option capable of attenuating the progression of PAD and ultimately impeding the development of plantar ulcers.

Transmissive-detected laser speckle contrast imaging for blood flow monitoring in thick tissue: from Monte Carlo simulation to experimental demonstration

“…Laser speckle contrast imaging (LSCI) is a wide-field, noninvasive imaging technique with high temporal and spatial resolution, which is based on the analysis of light signals after scattering and random interference, and therefore obtains the velocity information of scattering particles in biological tissues (e.g., red blood cells) 1 . Conventionally, it works on the reflective-detected mode, and has been widely used in the fundamental research of microcirculation 2 – 7 , whose dysfunction is highly relevant to a series of clinical symptoms, such as diabetes 8 , ischemic stroke 9 , 10 , coronary heart disease 11 and peripheral artery disease 12 . With surgery-based open-skull windows, thinned-skull windows, and surgery-free skull optical clearing windows, cortical blood flow distribution could be clearly observed using conventional reflective-detected LSCI technique 13 .…”

The Impact of Controlled Physical Training with Hydrotherapy on Changes in Swelling and Claudication Distance in Patients with Atherosclerotic Ischemia of the Lower Limbs

“…They assessed the temperature change on the sole of the big toe in response to local heating. The researchers found that in people with PAD, the activity of the endothelium, smooth muscles and the nervous system during heating was significantly lower compared to healthy controls [ 4 ]. Heat therapy, which is the use of an external heat source to raise local or systemic body temperature, has proven to be an effective intervention in patients with PAD [ 29 ].…”

“…In late-stage PAD, when tissue perfusion is no longer able to meet the metabolic demands of the tissues, critical limb ischemia can develop. This often leads to chronic ischemic pain, ulceration and eventually even amputation [ 3 , 4 ]. Patients are recommended to perform physical activity (i.e., walks lasting at least 30–45 min, walks 3 times a week) [ 3 , 5 , 6 ].…”

“…Structural changes related to the thermal stimulus, haemodynamic and vascular changes may lead to favorable adaptive changes in the skin microcirculation and thus play a key role in the prevention of ischemic ulcers. However, the mechanisms underlying the hemodynamic and structural adaptations induced by heat therapy are poorly understood [ 4 ].…”

Microcirculation disorders of the skin

“…Skin necrosis occurs (Figure 26c, d). 16,[51][52][53] There is a discrepancy between the total microcirculation and the purely nutritive microcirculation due to a maldistribution of blood flow between nutritive and nonnutritive vessels in ischemic skin. While nutritive blood flow in PAD patients has been comparable to that of healthy subjects for some time, total blood flow, as measured at the capillary level by LDF, is increased in PAD patients compared to healthy subjects.…”