In situ hemodynamics of perforating veins in chronic venous insufficiency

Purpose: The prevalence of incompetent perforators increases linearly with the clinical severity of chronic venous insufficiency (CVI) and the presenc e of deep vein incompetence. Putative transmission of deep vein pressure to skin may cause dermal hypoxia and ulceration. Despite extensive prospectiv e interest in the contribution of perforators toward CVI, their hemodynamic role remains controversial. The aim of this prospective study was to deter mine the in situ hemodynamic performance of incompetent perforating veins a cross the clinical spectrum of CVI, by means of duplex ultrasonography. Methods: A total of 265 perforating veins of 90 legs that had clinical sign s and symptoms consistent with CVI in 67 patients referred consecutively to the blood flow laboratory were studied. The clinical distribution of the e xamined limbs was CEAP(0), 10 limbs; CEAP(1-2), 39 limbs; CEAP(3-4), 21 lim bs; and CEAP(5-6), 20 limbs. With the use of gated-Doppler ultrasonography on real-time B-mode imaging, the flow velocity waveforms were obtained from the lumen of perforators on release of manual distal leg compression in th e sitting position and analyzed for peak and mean velocities, time to peak velocity, volume flow, venous volume displaced outward, and flow pulsatilit y. The diameter and duration of outward flow (abnormal reflux > 0.5 seconds ) were also measured. Results: Incompetent perforators had bigger diameters, higher peak and mean velocities and volume flow, longer time to peak velocity, and bigger venou s Volume displaced outward (VVoutward) than competent perforators (all, P < .0001). The diameter of incompetent perforators did not change significant ly with CEAP class (all, P > .1). Incompetent thigh and lower-third calf pe rforators had a significantly bigger diameter than perforators in the upper and middle calf combined (both, P < .05), in incompetent perforators: refl ux duration was unaffected by CEAP class or site (P > .3); peak velocity wa s higher in those in CEAP(3-4) than those in CEAP(1-2) (P = .024); mean vel ocity in those in CEAP(3-6) during the first second of reflux was twice tha t of those in CEAP(1-2) (P < .0001); both higher volume flow and VVoutward were found in the thigh perforators than those in the upper and middle calf thirds (P < .03); CEAP(3-6) volume flow and VVoutward, both in the first s econd, were twice that in those in CEAP(1-2) (P < .002); flow pulsatility i n those in CEAP(5-6) was lower than in those in CEAP(1.2) (P = .014); in de ep vein incompetence, higher peak velocity, volume flow, VVoutward, and dia meter occurred than in its absence (P < .01). CEAP designation correlated s ignificantly with mean velocity and flow pulsatility, both in the first sec ond (r = 0.3, P < .01). The flow direction pattern in perforator incompeten ce was uniform across the CVI spectrum: inward on distal manual limb compre ssion, and outward on its release; competent perforators had a smaller perc entage of outward flow on limb compression (P <.01). Conclusion: In additio n to an increase in diameter, perforator incompetence is characterized by s ignificantly higher mean and peak flow velocities, volume flow, and venous volume displaced outward, and a lower flow pulsatility. Differences in earl y reflux enable a better hemodynamic stratification of incompetent perforat ors in CVI classes. In the presence of deep reflux, incompetent perforators sustain further hemodynamic impairment. In situ hemodynamics enable quanti fication of the function of perforators and can be used in the identificati on of the clinically relevant perforators and the impact of surgery.