Thromboangiitis obliterans and endothelial function

Endothelial dysfunction may be involved in the pathophysiology of thromboangiitis obliterans (TAO). This study compares endothelial function and large artery stiffness between 10 TAO patients assessed during an exacerbation phase and 10 age- and sex-matched control subjects.

Flow-mediated vasodilation after gradual hand skin heating (from 28 degrees C to 44 degrees C) and endothelium-independent vasodilation after sublingual administration of 150 microg glyceryl trinitrate (GTN) were studied using a high-resolution echotracking system to simultaneously measure the brachial artery (BA) diameter and changes in wall shear stress. Aortic stiffness was assessed by carotid-to-femoral pulse wave velocity.

The baseline BA diameter was significantly smaller in TAO patients (3599 +/- 668 microm) than in control subjects (4114 +/- 671, P = 0.04). Hand warming caused a linear increase in shear stress accompanied by a linear increase in BA diameter as a function of increasing temperature for TAO patients and control subjects. There was no significant difference between the two groups [relative increase in BA diameter: + 9.3% (-0.1 to 11.5) vs. + 4.8% (3.0 to 8.1), respectively; P = 0.63]. The slope of the BA diameter vs. shear stress relationship did not significantly differ between the two groups. The relative increase in the BA diameter after GTN was significantly greater in TAO patients than in controls [+ 30.8% (28.6 to 33.6) vs. + 16.2% (12.6 to 21.9) respectively; P = 0.02]. Finally, TAO patients had greater aortic stiffness than control subjects (9.81 +/- 1.72 m s(-1) vs. 7.82 +/- 0.84 m s(-1) respectively; P = 0.0052).

Acute TAO is characterised by vasoconstriction and increased aortic stiffness in the absence of changes in flow-mediated dilation.