Contrasting Effects of Varicose Vein Surgery on Endothelial-dependent and -independent Cutaneous Vasodilation in the Perimalleolar Region

Venous stent placement ameliorates cutaneous microvascular function in iliocaval venous obstruction

BACKGROUND

The role of cutaneous microvascular dysfunction is well known in the development of chronic venous disease. However, the effects of venous obstruction on microcirculation have not been well investigated. The aim of this study was to assess cutaneous microvascular function in patients with iliocaval venous obstruction (ICVO) before and after venous stent placement.

METHODS

Endothelium-dependent and endothelium-independent vasodilator responses to iontophoretic administration of incremental doses of acetylcholine (ACh) and sodium nitroprusside (SNP) were evaluated using a laser Doppler scanner in the perimalleolar region in the supine and sitting positions in patients with ICVO (n = 11) and in healthy control subjects (n = 15). Cutaneous microvascular function, the Venous Clinical Severity Score (VCSS), and the Clinical, Etiology, Anatomy, and Pathophysiology (CEAP) clinical class were re-evaluated 3 months after stent placement in patients with ICVO.

RESULTS

The vasodilatory responses to ACh and SNP in the cutaneous microcirculation were lower in patients with ICVO than in healthy subjects in the sitting position (P < .05). Recanalization and stent placement were successful in all patients in the evaluation of VCSS and clinical class, and a significant decrease was determined in the signs and symptoms of the venous disease (P < .01). Stent placement resulted in a significant increase in vasodilation response to both ACh and SNP in the supine position and no improvement in the sitting position in patients with ICVO.

CONCLUSIONS

ICVO impairs endothelium-dependent and endothelium-independent vasodilation in the perimalleolar region. Iliocaval venous stent placement may recover microvascular dysfunction at different levels.

Effects of surgery on microvascular function in venous insufficiency

BACKGROUND

The aim of our study was to assess the effects of venous stripping on microvascular functions in isolated great saphenous vein insufficiency.

METHODS

Two groups of participants were prospectively evaluated. The first group included 15 healthy participants without any evidence of venous insufficiency. The second group included 20 patients with varicose veins because of great saphenous vein insufficiency. The demographics, venous clinical severity scores, and CEAP classifications of the patients were recorded. Next, all individuals underwent evaluations for microvascular vasoreactivity using an iontophoretic laser Doppler imager, and the outcomes were recorded. Patients with varicose veins underwent stripping surgeries, and microvascular vasoreactivity evaluations were repeated 6 weeks postoperatively.

RESULTS

There was a statistically significant decrease in the patients with varicose veins compared with the control group in response to nitroprusside (SNP) applied at 4 mC in the supine position. Furthermore, there was also a significant difference in the response to acetylcholine (ACh) in patient group in the sitting position (P < 0.05). We also observed a statistically significant decrease in the responses to SNP applied for 1, 2, and 4 mC (P < 0.05) in the patients in the sitting position. The relief of pain and edema after surgery was found to be significant (P < 0,001). In the subgroup in which ACh was applied for 1 and 4 mC in the supine position, postoperative microvascular flow was significantly increased (P < 0.005). Moreover, based on the measurements taken in the supine position, the patients in the subgroup in which SNP was applied for 1, 2, or 4 mC exhibited significantly increased postoperative microvascular dilatation (P < 0.005).

CONCLUSIONS

Saphenous vein insufficiency impairs the endothelium-dependent vasodilatation response in the perimalleolar region, and partial recoveries in microvascular function were observed after surgical treatment.

Seasonal variation in plasma free normetanephrine concentrations: implications for biochemical diagnosis of pheochromocytoma

BACKGROUND

Higher plasma concentrations of catecholamines in winter than in summer have been established, but whether this impacts the plasma concentrations of metanephrines used for the diagnosis of pheochromocytoma is unknown.

OBJECTIVE

In this study, we examined seasonal variations in the plasma concentrations of metanephrines, the impact of this on diagnostic test performance and the influences of forearm warming ('arterialization' of venous blood) on blood flow and measured concentrations.

METHODS

The measurements of the plasma concentrations of metanephrines were recorded from 4052 patients tested for pheochromocytoma at two clinical centers. Among these patients, 107 had tumors. An additional 26 volunteers were enrolled for the measurements of plasma metanephrines and forearm blood flow before and after forearm warming.

RESULTS

There was no seasonal variation in the plasma concentrations of metanephrines among patients with pheochromocytoma, whereas among those without tumors, the plasma concentrations of normetanephrine were higher (P<0.0001) in winter than in summer. Lowest concentrations of normetanephrine were measured in July, with those recorded from December to April being more than 21% higher (P<0.0001). These differences resulted in a twofold higher (P=0.0012) prevalence of false-positive elevations of normetanephrine concentrations in winter than in summer, associated with a drop in overall diagnostic specificity from 96% in summer to 92% in winter (P=0.0010). Forearm warming increased blood flow and lowered (P=0.0020) plasma normetanephrine concentrations.

CONCLUSIONS

The plasma concentrations of normetanephrine are subject to seasonal variation with a resulting higher prevalence of false-positive results in winter than in summer. Lowered plasma concentrations of normetanephrine with forearm warming suggest an effect of temperature. These results have implications for considerations of temperature to minimize false-positive results.

Impaired microvascular endothelial function is restored by acute lower-limb exercise in post-surgical varicose vein patients

Evidence exists that cutaneous microvascular endothelial dysfunction persists in patients following varicose vein surgery. This study compared cutaneous microvascular function between post-surgical varicose vein patients and healthy controls and investigated whether any impairment of function can be attenuated by acute lower-limb exercise. Cutaneous flux responses of the gaiter area were measured in supine and standing positions before and after a 25-min walk using laser Doppler fluximetry and incremental-dose administration of acetylcholine (ACh) and sodium nitroprusside (SNP). The pre-exercise peak responses to ACh (standing) were lower in patients than controls (48+/-11 vs. 96+/-28 PU; P=0.032), whereas treadmill exercise abolished this difference (P=0.819). In contrast, the pre-exercise responses to SNP (standing) appeared higher in patients than controls (3 mC responses: 24+/-4 vs. 10+/-2 PU, respectively; P=0.023), with no effect of acute exercise (P>0.05). These findings suggest that acute treadmill exercise augments microvascular endothelial function in post-surgical varicose vein patients to levels observed in age-matched controls.