Measurement of ambulatory venous pressure and column interruption duration in normal volunteers.

BACKGROUND: Ambulatory venous pressure (AMVP) measurement is considered the gold standard in evaluating calf pump function in chronic venous disease. The AMVP protocol was standardized in the 1970s with pressure monitoring through the dorsal foot vein. This technique was based on the belief that it represents calf venous pressure dynamics owing to rapid equilibration in the superficial and deep systems. This notion is subject to some doubt not only on theoretical grounds, but also owing to a lack of clinical correlation in a segment of the population with chronic venous disease. Our aims were to (1) examine if AMVP measured simultaneously through the dorsal foot vein (DFV) and the great saphenous vein (GSV) would be similar and (2) attempt to devise a noninvasive substitute via duplex measurement for the AMVP test. METHODS: The study was conducted in 76 limbs in 38 normal volunteers. Simultaneous AMVP measurements in DFV and GSV were made in 28 of these normal limbs. Column interruption duration (CID) after calf pump ejection was measured by monitoring duplex resumption of flow in the tibial veins and GSV after calf ejection. The return of AMVP back to baseline implies column restoration. The venous refill time therefore represents the CID via the pressure method. The pressure and duplex methods of CID were compared in the GSV. RESULTS: Key AMVP parameters (percent drop and venous refill time) significantly differed in DFV and GSV, showing a lack of pressure equilibration. CID measured by duplex in GSV was not significantly different from pressure-derived CID in the same vein. CONCLUSIONS: AMVP measured through the DFV does not reflect calf pump generated pressure events in GSV. A duplex method of measuring CID in GSV and posterior tibial vein is described. Duplex-derived CID is not significantly different from pressure-derived CID in the GSV.

The diagnostic unreliability of classic physical signs of lymphedema.

OBJECTIVE: In most communities, the diagnosis of lymphedema in the lower extremity currently rests on clinical signs. Lymphoscintigraphy, which is objective, is performed infrequently to confirm the clinical suspicion. Given absence of a curative option for lymphedema, it is essential to obtain an accurate diagnosis before committing the patient to lifelong conservative therapy. The aim of this study was to evaluate the diagnostic accuracy of clinical signs in comparison to lymphoscintigraphy, the current objective standard. METHODS: Retrospective review of contemporaneously collected data of 636 consecutive limbs with swelling (318 left, 318 right) that underwent initial evaluation during a 12-month period between 2016 and 2017 was performed. All limbs were assessed for classic clinical signs of lymphedema including dorsal hump of the foot, square toes, Kaposi-Stemmer sign, and nonpitting edema. Lymphoscintigraphy was routinely performed for objective evaluation. The 436 patients who underwent the study were scored positive for lymphedema on the basis of transit time delay for the radioisotope in minutes, presence of dermal backflow, presence of collateral channels, intensity of uptake in the main channel and lymph nodes, number of nodes in the groin, and presence of popliteal nodes. Analysis was carried out to determine sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the clinical signs in determining whether a patient had lymphedema. In addition, regression analysis was carried out to evaluate the predictive value of different clinical signs in determining lymphedema. Patients with positive clinical signs but with normal findings on lymphoscintigraphy who did not have a medical cause for swelling underwent workup to determine a possible venous cause. RESULTS: Of 636 limbs with swelling, 436 (69%) underwent lymphoscintigraphy, the findings of which were normal in 178 (41%) and abnormal in 258 (59%). Of the 636 swollen limbs, 96 (15%) had clinical signs of lymphedema; 95% had dorsal hump, 37% had square toes, 32% had presence of Kaposi-Stemmer sign, and 12% had nonpitting edema. Of these 96, lymphoscintigraphy was performed on 66 (69%); 45 of 66 (68%) patients with clinical signs were positive for lymphedema; the remaining 32% were normal. Conversely, among 258 swollen limbs with abnormal findings on lymphoscintigraphy, only 45 (17%) had one or more of the clinical signs. Sensitivity and specificity of clinical signs in predicting lymphoscintigraphy-confirmed lymphedema were 17% and 88%, respectively. Overall accuracy was 47%. Of the clinical signs, only the Kaposi-Stemmer sign was a significant predictor of lymphedema (odds ratio, 7.9; P = .02). In patients with positive clinical signs but normal findings on lymphoscintigraphy, venous obstruction was the most common cause of swelling. CONCLUSIONS: Clinical signs of lymphedema appear to be unreliable in making a correct diagnosis of lymphedema in one-third of patients. Conversely, in lymphoscintigraphy-confirmed lymphedema, only 17% had positive clinical signs. Of the clinical signs, only Kaposi-Stemmer sign has some predictability in determining lymphoscintigraphy-confirmed lymphedema. Venous obstruction is the most common cause of clinical signs in patients without lymphedema. Routine use of lymphoscintigraphy is recommended in patients to make an objective diagnosis of lymphedema.

Ambulatory venous pressure, air plethysmography, and the role of calf venous pump in chronic venous disease.

BACKGROUND: Ambulatory venous pressure (AMVP) records pressure dynamics with calf exercise. Air plethysmography (APG) measures related volume detail. APG has been suggested as a noninvasive surrogate for AMVP. We examine the correlations between APG and AMVP parameters and the role of "calf pump failure" in chronic venous disease (CVD). METHODS: A total of 8456 limbs in 4610 patients investigated for CVD during a 20-year period were analyzed. APG and AMVP data were available in 4599 limbs for calculation of Pearson correlation coefficient; 1347 of these limbs had significant iliac vein stenosis, proven by intravascular ultrasound. Venn diagrams are used to explore overlapping incidence of APG and AMVP abnormalities. RESULTS: APG calf volume and reflux (venous volume, venous filling index) showed progressively significant deterioration with advancing Clinical, Etiology, Anatomy, and Pathophysiology (CEAP) clinical class, anatomic extent of reflux (superficial, deep, perforator), and reflux severity (axial reflux, segmental score). Notably, calf ejection volume increased in a nearly linear fashion (R = 0.71) to venous volume such that residual volume fraction (RVF) remained normal even in the worst of these categories. AMVP too progressively deteriorated with clinical disease and reflux severity. Venous filling time was the key parameter as the pressure drop alone was abnormal in only 4% of the limbs analyzed. There was no correlation between RVF and AMVP (R = 0.22) or between AMVP and many other APG parameters. Venn distribution showed only minor overlap (30%) between AMVP and key APG abnormalities overall, but the overlap increases from 40% to 70% in advanced clinical and reflux categories. AMVP was rarely abnormal (7%) when APG was normal. Median AMVP was normal in calf pump failure categories, however defined (subnormal ejection fraction, RVF, or both). Median AMVP is normal in venous obstruction without reflux, while AMVP abnormalities are associated three to seven times more with reflux than with obstruction. CONCLUSIONS: APG (venous filling index) is a useful index of reflux. Calf pump ejection is a powerful and plastic compensatory mechanism, and calf pump failure is rare. Ambulatory venous hypertension is dominantly associated with reflux and less with obstruction. AMVP too worsens with clinical and reflux severity categories. However, there is little correlation between APG and AMVP parameters as APG measures volume and AMVP measures pressure, each in its own domain, and the volume-pressure curve is nonlinear. AMVP may be omitted in routine clinical testing if APG is normal, as the yield (7%) will be very low. AMVP reflects venous hypertension, the end stage in CVD. AMVP should be used to identify such cases when APG is abnormal.

Caliber-targeted reinterventional overdilation of iliac vein Wallstents.

BACKGROUND: Wallstents (Boston Scientific, Marlborough, Mass) are most commonly used in iliac-caval stenting. Approximately 20% of stented limbs require reintervention to correct in-stent restenosis (ISR) or stent compression (SC). Corrective balloon dilation to rated stent caliber (isodilation) is not always successful. We investigated whether modest overdilation of the Wallstent by 2 to 4 mm (10%-20%) beyond the rated diameter would yield better mechanical clearance of ISR/SC, leading to a larger flow channel, improved conductance, reduction of peripheral venous pressure, and better clinical outcome. Outflow lumen caliber exponentially influences peripheral venous pressure, a key mechanism in chronic venous disease. Beyond the mechanical effects, the rationale for overdilation rests on the theory that an improvement in flow channel at the margins may yield an outsized pressure reduction and clinical improvement. METHODS: There were 274 previously stented limbs that underwent reinterventional balloon dilation for clearance of ISR/SC during a recent 3-year period. Isodilation to rated diameter of the stent was judged effective in 71 limbs (isodilated subset); 203 limbs (overdilated subset) for which initial isodilation was ineffective underwent overdilation of the resident Wallstent by 2 to 4 mm (10%-20%) beyond the original rated diameter. IVUS planimetry was used intraoperatively to calculate SC and ISR and their subsequent clearance in the two subsets. The dilated segments were observed by clinical and duplex ultrasound examination afterward. The two subsets were compared in the following outcome measures: intraprocedural efficacy in clearing ISR/SC and achieving target lumen caliber, subsequent clinical outcomes, duplex ultrasound caliber durability, and improvement in supine foot venous pressures. This is a single-center retrospective analysis of data contemporaneously entered into a time stamped electronic medical record system. RESULTS: The median follow-up was 18 months (range, 1-35 months). Overdilation of the stent resulted in significantly better intraoperative flow channel area improvement per intravascular ultrasound. This was reflected in significantly better clinical outcome and improvement in peripheral venous pressure in the overdilated subset. Overdilation appeared to be durable up to 20 months after intervention by duplex ultrasound monitoring. CONCLUSIONS: Overdilation appears to be a useful technique to correct ISR/SC and to restore target lumen caliber during reinterventional correction of a resident iliac vein Wallstent. More durable caliber improvement, superior clinical outcome, and reduction in peripheral venous hypertension were noticed in overdilated stents compared with isodilation.