Non-invasive test may be useful to monitor blood flow complications

Flow-mediated dilation 'helpful tool in the overall assessment of vascular injury' by Lindsey Shapiro, PhD | January 16, 2024

A non-invasive technique called flow-mediated dilation (FMD) could be useful for monitoring blood vessel alterations in people with systemic sclerosis (SSc) and predicting the likelihood of certain blood flow (vascular) complications, a study has found.
The test findings show distinct differences between SSc patients and healthy people, and were more altered in SSc patients who had been living with the disease longer and had certain vascular symptoms, including pulmonary arterial hypertension (PAH).
This correlated well with the degree of damage seen in other tests of vascular damage as well as blood biomarkers of the endothelial cell dysfunction thought to drive blood vessel changes in SSc.
The study, “Flow Mediated Dilation in Systemic Sclerosis: Association with clinical findings, capillaroscopic patterns and endothelial circulating markers,” was published in Vascular Pharmacology.

Endothelial dysfunction drives blood vessel damage, blood flow changes
​Alterations to the endothelial cells that line blood vessels — called endothelial dysfunction — drive blood vessel damage and blood flow changes in SSc. As a result, patients may experience certain vascular complications such as Raynaud’s phenomenon, PAH, or digital ulcers.
Small blood vessels (i.e. capillaries) as well as larger vessels (i.e. veins and arteries) in patients may be affected, known as microvascular and macrovascular damage, respectively.
Microvascular damage is more common and better characterized. These changes can be assessed using a technique called nailfold video-capillaroscopy (NVC), where the capillaries under the skin near the fingernail beds are visualized under a microscope.
A method for detecting macrovascular damage is not as well established. FMD, which looks at an artery’s diameter in response to blood flow restriction, could be one way to do this, but it is not yet widely used in clinical practice.

Study examined 57 SSc patients, including 52 women and five men
In the study, scientists in Italy investigated FMD’s possible utility for monitoring and predicting vascular involvement in FMD. The relationships between clinical characteristics, FMD, NVC, and certain blood biomarkers were examined in 57 SSc patients and 37 healthy people.
The SSc patients, including 52 women and five men, had a mean age of 58.91 and had been living with SSc for a mean of nearly 12 years.
With the FMD technique, a cuff is placed on the arm and tightened to compress an artery of interest and restrict blood flow in that area. The artery’s diameter is measured before (at baseline) and after this process. Normally, once the cuff is released, endothelial cells in the artery will respond, or react, to increase artery diameter and boost blood flow.
While artery diameter did not differ between SSc patients and in healthy people at baseline, the FMD value after the cuff was released was significantly lower in the patients than healthy people, reflecting an altered endothelial response. Moreover, it took significantly longer for the maximum FMD value to be achieved after the cuff was released.
Among SSc patients, this endothelial dysfunction was associated with a longer disease duration and the presence of PAH — high blood pressure in the blood vessels of the lungs — in final statistical analyses. Digital ulcers, or sores on the fingers due to restricted blood flow, were also linked to an altered FMD response but the relationship was not significant in final analyses.

More microvascular damage linked to longer SSc duration, PAH, digital ulcers
More substantial FMD alterations were also associated with patterns of more significant microvascular damage assessed by NVC. More advanced microvascular involvement was similarly linked to longer disease duration, PAH, and digital ulcers.
Biomarkers of endothelial cell dysfunction were elevated in SSc patients relative to healthy people. Higher circulating levels of two biomarkers in particular — VEGF and angiopoietin-2 — were associated with greater FMD alterations, as well as PAH and digital ulcers.
Altogether, “FMD could be a sensitive marker for detecting endothelial dysfunction in SSc patients,” the researchers wrote, adding it may be “a helpful tool in the overall assessment of vascular injury.”
When combined with NVC, FMD may be particularly useful for predicting the risk of vascular problems such as PAH and digital ulcers, the scientists noted.
“Further studies on a larger case series should be performed to validate the use of FMD as a tool in clinical practice,” the team concluded.