Increased arterial inflow in extremities with chronic venous insufficiency: an important and unappreciated hemodynamic parameter

Time taken to the maximum increase in the oxygenated hemoglobin level in calf muscle as a predictor of mild and moderate post-thrombotic syndrome

BACKGROUND

Near-infrared spectroscopy (NIRS) allows continuous noninvasive monitoring of changes in the tissue levels of oxygenated hemoglobin (O2Hb) and deoxygenated hemoglobin (HHb) and can identify the severity of chronic venous diseases. Here we investigated the predictors of post-thrombotic syndrome (PTS) using NIRS in patients with a first episode of deep venous thrombosis (DVT).

METHODS

The study enrolled 129 patients with DVT. Risk factors in each patient were assessed at presentation. Venous abnormalities confirmed by ultrasound and parameters derived from NIRS were evaluated at 6 months after DVT. On standing, increases in O2Hb and HHb (ΔO2Hbst and ΔHHbst) and the times taken for each concentration to become maximal (TO2Hbst, and THHbst) were measured. During 10 tiptoe movements, O2Hb showed a continuous decrease (ΔO2Hbex), whereas venous expulsion (ΔHHbEex) and subsequent retention (ΔHHbRex) were observed. The oxygenation index (HbD; HbD = O2Hb - HHb) was also calculated at the end of standing and at the end of 10 tiptoe movements (ΔHbDst and ΔHbDex). Final clinical manifestations were evaluated at 6 years, and PTS was considered to be present if the Villalta score was ≥5.

RESULTS

Thirteen patients were excluded and 116 patients were finally included. Of these, 19 (16%) developed PTS. Among various NIRS-derived parameters, TO2Hbst had the highest area under the curve (0.88; 95% confidence interval [CI], 0.80-0.93; P < .01) with the best cutoff value (TO2Hbst ≤48 seconds). On univariate analysis, variables associated with greater risk for development of PTS were stroke (odds ratio [OR], 5.59; 95% CI, 0.74-42.41; P = .06), idiopathic DVT (OR, 4.13; 95% CI, 1.36-12.55; P < .01) and iliofemoral DVT (OR, 4.31; 95% CI, 1.48-12.60; P < .01) at initial presentation, venous occlusion combined with reflux (OR, 4.24; 95% CI, 1.50-12.00; P < .01), and NIRS-derived TO2Hbst ≤48 seconds (OR, 43.03; 95% CI, 9.04-204.81; P < .01) at 6 months. Multivariate logistic regression analysis finally revealed venous occlusion combined with reflux (OR, 4.80; 95% CI, 1.03-22.36; P < .05) and NIRS-derived TO2Hbst ≤48 seconds (OR, 53.73; 95% CI, 8.43-342.41; P < .01) to be independently associated with PTS progression.

CONCLUSIONS

NIRS-derived TO2Hbst ≤48 seconds is a promising time-course predictor of PTS progression.

Measurement of calf muscle oxygenation during light-intensity exercise in patients with post-thrombotic syndrome

BACKGROUND

Near-infrared spectroscopy (NIRS) provides continuous noninvasive monitoring of changes in the levels of oxygenated hemoglobin (O2Hb) and deoxygenated hemoglobin (HHb) in tissues. The purpose of this study was to investigate changes in calf muscle O2Hb and HHb levels during standing and exercise in the follow-up of deep venous thrombosis (DVT).

METHODS

Forty-three patients with a first episode of unilateral proximal DVT were included. Final clinical manifestations were evaluated at a mean follow-up point of 53 months after diagnosis of DVT, and post-thrombotic syndrome (PTS) was considered to be present if the Villalta score was >5. Moreover, to assess the severity of PTS, the revised Venous Clinical Severity Score (VCSS) was employed. NIRS was used to measure changes in the levels of O2Hb and HHb in calf muscle. On standing, increases in O2Hb and HHb were calculated by subtracting the baseline value from the maximum value (ΔO2Hbst and ΔHHbst). The times taken for the O2Hb and HHb concentrations to become maximal (TO2Hbst, and THHbst) were also measured. During 10 tiptoe movements, the relative change in O2Hb was calculated by subtracting the value measured at the end of exercise from the value measured at the beginning of exercise (ΔO2Hbex). On the other hand, 10 tiptoe movements produced venous expulsion (ΔHHbEex) and a subsequent retention (ΔHHbRex). The oxygenation index (HbD; HbD = O2Hb - HHb) was also calculated at the end of standing and at the end of 10 tiptoe movements (ΔHbDst and ΔHbDex).

RESULTS

Among the 43 limbs evaluated, 21 had PTS. On standing, the ΔHbDst was significantly decreased in patients with PTS relative to the patients without PTS (12 ± 8, 22 ± 11 μmol/L; P = .001). The TO2Hbst was also significantly reduced in patients with PTS relative to those without (43 ± 41, 107 ± 58 seconds; P = .001). During 10 tiptoe movements, the ΔHHbEex was significantly reduced in patients with PTS relative to those without (-2 ± 1, -3 ± 3 μmol/L; P = .016). Similarly, the ΔHHbRex was significantly increased in patients with PTS relative to those without (8 ± 7, 3 ± 2 μmol/L; P = .001). Furthermore, falls in ΔHbDex were more pronounced in patients with PTS (-10 ± 16, 10 ± 10 μmol/L; P < .001). NIRS-derived TO2Hbst (r = -0.568; P < .001) and ΔHbDex (r = -0.645; P < .001) showed strong inverse correlations with VCSS. Similarly, NIRS-derived ΔHHbEex (r = 0.409; P < .01) and ΔHHbRex (r = 0.476; P < .01) showed moderate positive correlations and ΔHbDst (r = -0.422; P < .01) had a moderate inverse correlation with VCSS.

CONCLUSIONS

Changes in O2Hb and HHb concentrations differ between patients with and without PTS. The reduced TO2Hbst may indicate impairment of the venoarteriolar reflex in patients who have PTS. Furthermore, severe falls in HbD in patients with PTS might reflect the pain of venous claudication. These findings may have implications for investigations of the microcirculation in the context of post-thrombotic sequelae.

Measurements of calf muscle oxygenation during standing and exercise in patients with primary valvular insufficiency

OBJECTIVE

Despite the established role of the calf muscle pump for preventing chronic venous disorders, hemoglobin flow in the calf muscle is poorly understood. Near-infrared spectroscopy (NIRS) provides continuous noninvasive monitoring of changes in tissue-oxygenated hemoglobin (O2Hb) and deoxygenated hemoglobin (HHb) levels. The purpose of this study was to investigate the changes in calf muscle O2Hb and HHb levels during standing and exercise in patients with primary valvular insufficiency (PVI).

METHODS

Eighty-three limbs in 81 patients with PVI were enrolled. The clinical manifestations of these patients were categorized according to the CEAP (Clinical, Etiologic, Anatomical, and Pathophysiologic) classification, and patients were divided into group I (C1-3S,Ep,As,d,p,Pr) and group II (C4-6S,Ep,As,d,p,Pr). Moreover, to assess the severity of PVI, the revised Venous Clinical Severity Score (VCSS) was employed. NIRS was used to measure changes in the calf muscle O2Hb and HHb levels. On standing, increases in O2Hb and HHb were calculated by subtracting the baseline value from the maximum value (ΔO2Hbst and ΔHHbst). The time elapsed until the maximum increases in O2Hb and HHb concentrations (TO2Hbst, and THHbst) were also measured. During 10 tiptoe movements, the relative change in O2Hb was calculated by subtracting the value measured at the end of exercise from the value measured at the beginning of exercise (ΔO2Hbex). On the other hand, 10 tiptoe movements produced venous expulsion (ΔHHbEex) and a subsequent retention (ΔHHbRex). The oxygenation index (HbD; HbD = O2Hb - HHb) was also calculated at the end of standing and 10 tiptoe movements (ΔHbDst and ΔHbDex).

RESULTS

Among the 83 limbs evaluated, 48 were classified as group I and 35 as group II. Standing caused increases in the levels of both ΔO2Hbst and ΔHHbst. However, there were no significant differences in these increases between the two groups. In contrast, the TO2Hbst was significantly reduced in group II in comparison with group I (55 ± 29 vs 36 ± 30 seconds; P = .007). During 10 tiptoe movements, a decrease in O2Hb concentration was observed, and there was no significant difference in ΔO2Hbex between group I and group II. In contrast, the ΔHHbRex was significantly increased in group II compared with group I (6 ± 7 vs 9 ± 6 μmol/L; P = .013). Furthermore, falls in ΔHbDex were more pronounced in group II (7 ± 16 vs -7 ± 16 μmol/L; P = .001). A statistically significant correlation was found between C of CEAP and the VCSS (r = 0.778; P < .001). Moreover, NIRS-derived TO2Hbst (r = -0.312; P < .01) and ΔHbDex (r = -0.332; P < .01) showed moderate inverse correlations with C of CEAP. Similarly, NIRS-derived ΔHbDex (r = -0.501; P < .001) had a strong inverse correlation, and ΔHbDst (r = -0.383; P < .001) and TO2Hbst (r = -0.378; P < .001) had moderate inverse correlations with VCSS.

CONCLUSIONS

Changes in O2Hb and HHb concentrations differ according to CEAP manifestation and VCSS. These data offer new insights into calf muscle hemodynamics at the microcirculation level in patients with PVI.

Ultrasound findings after radiofrequency ablation of the great saphenous vein: Descriptive analysis

OBJECTIVE

As an emerging endovascular alternative to ligation and stripping of the incompetent greater saphenous vein (GSV), radiofrequency ablation was monitored with ultrasound scanning to evaluate anatomic results. Neovascularization and inflammation are potential consequences that lead to the appearance of small vessels. The natural history of the below-knee untreated GSV segment may be important in our understanding of ongoing chronic venous disease. An ultrasound follow-up study was conducted to determine the prevalence of small vessel networks, defined as veins and arteries less than 2 mm in diameter, adjacent to the saphenofemoral junction (SFJ); prevalence of small vessel networks adjacent to the treated GSV in the thigh; and fate of the below-knee untreated GSV distal to the ablated segment.

METHODS

One hundred six extremities with radiofrequency ablation of the GSV for treatment of superficial venous insufficiency were followed up with high-resolution ultrasound imaging 4 to 25 months (median, 9 months) after the procedure. Ninety-three limbs had concomitant ligation and division of the SFJ and its tributaries, and 13 limbs underwent radiofrequency ablation without SFJ ligation. Ultrasound was used to evaluate patients for small vessel networks, and concomitant findings of small vessel networks and recanalization at the SFJ and adjacent to the treated GSV. The status of the below-knee segment of untreated GSV was evaluated for patency and reflux. Data analysis compared the findings in the ligation group with those in the no-ligation group, with the chi 2 test and Fisher exact test.

RESULTS

We found small vessel networks in 65% (n = 69) of extremities: 15% (n = 16) at the SFJ only, 26% (n = 28) in the thigh only, and 24% (n = 25) at both the SFJ and thigh, resulting in a small vessel network prevalence of 39% (n = 41) at the SJF and 50% (n = 53) in the thigh. The prevalence of small vessel networks at the SFJ was significantly less after radiofrequency ablation with SFJ ligation (34%, 32 of 93) than after radiofrequency ablation without ligation (69%, 9 of 13; P = .035). Small vessel networks and GSV recanalization at the SFJ was more common in patients undergoing radiofrequency ablation without ligation (46%, 6 of 13) than after radiofrequency ablation with ligation (14%, 13 of 93; P = .014). The prevalence of small vessel networks in the thigh was not affected by SFJ ligation. The below-knee GSV was patent in 79% (84 of 106), and 58% (61 of 106) demonstrated reflux, a decrease from the pre-radiofrequency ablation rate of 71% (75 of 106), possibly because thrombosis extended distally beyond the ablated segment in 16% (17 of 106) of the legs.

CONCLUSIONS

Small vessel networks were detected adjacent to or in connection with most of the radiofrequency ablation-treated GSVs. SFJ ligation was associated with fewer small vessel networks and proximal GSV recanalization. Most below-knee untreated GSV segments remained patent, and most exhibited reflux.

Pathophysiology of venous ulcers: surgical implications, review, and update

BACKGROUND

Ambulatory venous hypertension has long been accepted as the principal and sole factor underlying the development of venous ulcers of the leg. This concept is now being seriously challenged as other factors emerge as important in the pathophysiology of venous ulcers.

OBJECTIVE

This study was undertaken in order to review and update the current thinking concerning the pathophysiology of venous ulcers of the leg.

METHOD

A review of the current medical literature.

RESULTS

The prevailing current thinking about the pathophysiology of venous ulcers of the leg reveals that ambulatory venous pressure is the initiating factor. Over time this causes endothelial damage by the activation of leukocytes with subsequent release of proteolytic enzymes along with free oxygen radicals, leading to tissue damage which over time may cause ulceration.

CONCLUSIONS

The production of venous ulcers of the leg is more complex than what was first thought. Although it is most likely that inflammatory factors are involved in its production, the cascade of inflammatory events postulated to occur need further investigation and clarification.

Air plethysmography in chronic venous insufficiency: clinical diagnosis and quantitative assessment

To define the role of air plethysmography (APG) in the clinical diagnosis and quantitative assessment of chronic venous insufficiency (CVI), APG studies were performed on 582 limbs in 291 patients with signs and symptoms of CVI. One hundred and thirty-one limbs were classified into group I (no evidence of CVI), 291 into group II (mild CVI), and 160 into group III (advanced CVI). On APG, the mean venous filling index (VFI) was 1.45 mL/s, 3.90 mL/s, and 5.25 mL/s in groups I, II, and III respectively (p<0.05). The mean ejection fraction (EF) and mean residual volume fraction (RVF) also showed significant differences between the limbs with CVI and the contralateral normal limbs, but the values were similar for the different severities of CVI limbs. The amount of overlap in VFI, EF, and RVF values among the clinical groups was considerable. Discrimination analysis derived a VFI value of 2.67 mL/s as a cutoff point between normal limbs and limbs with CVI, with a positive predictive value of 96%. In conclusion, APG is a simple and noninvasive test for quantitative assessment of the different components of CVI, valvular reflux, and calf muscle pump function. However, only VFI correlated significantly with the severity of CVI. VFI, with its high positive predictive value, may be useful in diagnosis of CVI, and it may serve as an objective quantitative measurement for monitoring the effect of treatment.

Venous morbidity after superficial femoral-popliteal vein harvest

PURPOSE

The superficial femoral-popliteal vein (SFPV) is a reliable conduit for aortoiliac, infrainguinal, and venous reconstructions. In this prospective study, we characterized the anatomic and physiologic changes in SFPV harvest limbs and their relationship to the development of late venous complications.

METHODS

Since 1990, we have studied 61 patients after harvest of 86 SFPVs at 6-month intervals with clinical examinations, lower-extremity venous duplex, and venous function tests. The CEAP system was used as a means of categorizing clinical changes.

RESULTS

Mean (+/- SEM) follow-up was 37 +/- 3 months. Less than one third of harvest limbs had edema without skin changes (C3). No patient had major chronic venous changes (C4 to C6) or venous claudication. There were no significant differences in limb measurements between harvest and non-harvest limbs, except in a subgroup of patients with unilateral harvest in which there was a small but significant (P =.046) increase in harvest limb thigh and calf circumference, compared with the opposite non-harvest limb. These clinical results were not affected by the presence or absence of an intact greater saphenous vein (GSV). Large, direct collaterals (4 to 6 mm in diameter) between the popliteal vein stump and profunda femoris vein (PFV) were seen by means of duplex ultrasonography in 29 harvest limbs (34%). The remainder appeared to have smaller, less direct collaterals to the PFV. Mild venous reflux with rapid cuff deflation was present at the popliteal or posterior tibial vein in nine of 79 harvest limbs (11%). Six of these nine limbs (67%) with reflux were clinical class C3, compared with only 19 of the 70 limbs without reflux (27%; P =.02). Ambulatory venous pressure (AVP) with exercise was significantly increased in harvest limbs (60 +/- 4.7 mm Hg), compared with non-harvest limbs (47.8 +/- 5.2 mm Hg; P =.049). The AVP recovery time of harvest limbs (14.0 +/- 1.0 seconds) was reduced, compared with non-harvest limbs (23.5 +/- 4.5 seconds; P =.02). AVPs (exercise) remained stable or decreased in six of 10 harvest limbs measured serially. Venous refill time in harvest limbs (15.1 +/- 1.1 seconds) was shortened, compared with non-harvest limbs (22.3 +/- 2. 1 seconds)(P =.002). Venous outflow obstruction measured by means of plethysmography was present in 93% of harvest limbs, compared with 36% of non-harvest limbs (P =.001).

CONCLUSION

SFPV harvest results in minimal mid-term to late-term lower-extremity venous morbidity despite outflow obstruction. The most likely mechanisms preserving clinical status include the low incidence of mild reflux, the presence of collateral venous channels, and the lack of progression in abnormal harvest limb physiology. The absence of the ipsilateral GSV does not adversely affect clinical outcome.

Where does venous reflux start?

PURPOSE

This study was designed to identify the origin of lower limb primary venous reflux in asymptomatic young individuals and to compare patterns of reflux with age-matched subjects with prominent or clinically apparent varicose veins.

METHODS

Forty age- and sex-matched subjects with no symptoms (age, 15 to 35 years; 80 limbs; group A), 20 subjects (age, 19 to 32 years; 40 limbs) with prominent but nonvaricose veins (n = 26 limbs; group B), and 50 patients (age, 17 to 34 years; 100 limbs) with varicose veins (n = 64; group C) were examined with color flow duplex imaging. All proximal veins (above popliteal skin crease), superficial, perforator, and deep, in the lower limb were examined in the standing position, and all the distal veins in the sitting position. Patients who had a documented episode of superficial or deep vein thrombosis, previous venous surgery, or injection sclerotherapy were excluded from the study.

RESULTS

The prevalence of reflux in group A was 14% (11 of 80), in group B 77% (31 of 40), and in group C 87% (87 of 100). In more than 80% of limbs in the three groups, reflux was confined to the superficial veins alone. Deep venous reflux or combined patterns of reflux were uncommon even in group C. Reflux was detected in all segments of the saphenous veins and their tributaries. In the 125 limbs that had superficial venous incompetence, the below-knee segment of the greater saphenous vein was the most common site of reflux (85, 68%), followed by the above-knee segment of greater saphenous vein (69, 55%) and the saphenofemoral junction (41, 32%). Nonsaphenous reflux was rare (3, 2.4%). Reflux in the lesser saphenous vein (21, 17%) was seen in all groups, whereas involvement of both greater and lesser saphenous veins (8, 6.4%) was seen in group C alone. The incidence of multisegmental reflux was significantly higher in group C (61 of 64, 95%) than in group A (two of 11, 18%) or group B (14 of 26, 54%). The prevalence of distal reflux was comparable in all groups.

CONCLUSIONS

Primary venous reflux can occur in any superficial or deep vein of the lower limbs. The below-knee veins are often involved in asymptomatic individuals and in those who have prominent or varicose veins. These data suggest that reflux appears to be a local or multifocal process in addition to or separate from a retrograde process.