Applications - Peripheral Vascular Diseases

Many believe that the growing problem of obesity will significantly expand the incidence of Type II diabetes, with an ensuing increase in peripheral vascular disease. Even in well-controlled diabetics, long-term damage to the peripheral microvascular bed is evident. We believe that the availability of compact, robust devices that can be worn comfortably for extended periods of time could prove key in gaining basic insight into early microvascular changes. Such measures could also provide objective feedback of the influence of lifestyle changes and the long-term effects of drugs aimed at stabilizing carbohydrate disorders.

Investigating PVD with DYNOT

Optical imaging of PVD

Protocols for forearm provocation involving long-term diabetics have produced results revealing a statistically significant inverse relationship between the rates of recovery following venous occlusion and plasma hemoglobin A1c levels, an established marker of long-term control of glucose metabolism. In addition, reduced recovery rates often are accompanied by a marked decrease in vascular contrast features seen in cross section suggestion the presence of occlusive disease (see figure to the right, left panel: healthy; right panel: PVD patient).

Studies have furthermore demonstrated clear relationships between recovery rates and factors that influence peripheral vascular resistance (PVR). The assessment of this parameter holds high significance in acute care medicine. Currently PVR measures require placement of a Swan-Ganz catheter in the pulmonary artery, which is a highly invasive procedure not without risk.

Other areas where DYNOT measures could prove particularly useful are in the assessment of compartment syndrome and for detecting focal occlusive events associated with sickle cell crises. The latter is a disease that mainly effects children and presents clinicians with few options for determining when emergency transfusions are warranted. With DYNOT, assessment of perfusion disorders can be performed without the risk of anesthesia that is inherent to MR studies of young children.

Value/Advantages

• Excellent sensitivity to perfusion state of microvascular bed.
• Feasibility of employing sensor arrays suitable for long-term monitoring.
• Economical, compact systems.

Competing Technologies

Vascular ultrasound, x-ray angiography, and MR-angiography are the main technologies employed to assess blood flow disorders. All are costly, and none is well suited to explore that functional state of the microvasculature.