QSART Assessment of Venous Autonomic Modulation
Authors: Arata M., Debarge P.
Diagnostic tests used to assess autonomic nervous system (ANS) function such as heart rate variability (HRV) have been applied in MS and track with physical disability and disease progression. Sympathetic activity in particular correlates with MS disease activity which can be assessed by sudomotor testing. It has recently been shown that venous balloon dilation improves ANS function in multiple sclerosis (MS) patients. This effect is hypothesized to result from balloon stimulation of the venous distension reflex (VDR) leading to increased sympathetic tone. The objective of this study was to evaluate sudomotor for sympathetic assessment following venous balloon dilation.
Seventeen MS patients (12 women and 5 men), aged 34–79 years (mean = 51), with sudomotor confirmed sympathetic autonomic dysfunction underwent venous balloon dilation therapy. All procedures were performed at an outpatient vascular center with light sedation. Bilateral internal jugular, azygous, and left renal vein dilation was performed. Noncompliant balloons were used to result in vessel over-dilation of 10-20%. Jugular and azygos dilation was at the valvular level as depicted by IVUS. The left renal vein was dilated at site of maximal compression or one cm from the confluence of the renal vein and the inferior vena cava in the absence of compression. Inclusion criteria was ability to cannulate and exclusion criteria was the presence of acute thrombus.
All seventeen procedures were completed successfully without acute adverse events in an outpatient center. Sudomotor testing demonstrated improved an increase in sweat volume at the foot from 0.180 to 0.295, Wilcoxon signed rank test (p=0.02) following treatment.
The results demonstrate statistically significant improvement in sympathetic tone in MS patients following venous balloon dilation. This is consistent with previous reports of improvements in BP and the postural component of HRV tests, which also represent alterations of sympathetic tone, following venous balloon treatment. The effect upon the sympathetic system by venous dilation is thought to represent activation of the venous distension reflex. Procedural improvement of autonomic dysfunction may have implications for treating other autonomic conditions. Further investigation is encouraged.