Oxygen Uptake Kinetics during Exercise Reveal Central and Peripheral Limitation in Patients with Ilio-Femoral Venous Obstruction.

Reuveny R; Luboshitz J; Bar-Dayan A; DiMenna FJ; Jones AM; Segel MJ;

Journal of vascular surgery. Venous and lymphatic disorders [J Vasc Surg Venous Lymphat Disord] 2021 Dec 24.
Date of Electronic Publication: 2021 Dec 24.

Objective: Pulmonary oxygen uptake (V̇O 2 ) kinetics measured during initiation of exercise mirror energetic transition during daily activity. The aim of this study was to elucidate the pathophysiological mechanisms of exercise limitation of patients with chronic ilio-femoral vein obstruction after deep vein thrombosis by measuring V̇O 2 kinetics compared to patients with peripheral arterial disease (PAD) and healthy individuals.
Methods: Eleven patients with ilio-femoral vein obstruction (7 man, age 20-65 yrs.), seven patients with PAD (all men, age 44-60 yrs.) and eight healthy participants (5 men, age 28-58 yrs.) were studied. Participants performed upper and lower-limb symptom-limited cardiopulmonary exercise tests on cycle ergometers; and four repeat lower-limb tests at a constant work-rate (WR) corresponding to 90% of the gas exchange threshold for determining V̇O 2 kinetics.
Results: Phase I V̇O 2 amplitude in the constant WR tests (% increase over resting V̇O 2 ), representing the initial surge in cardiac output caused by the emptying of leg veins, was 59±19% in the ilio-femoral vein obstruction group, 73±22% in peripheral arterial disease and 85±26% in healthy participants (p=0.055 for ilio-femoral vein obstruction vs. healthy). Phase II V̇O 2 kinetics, which largely reflect the kinetics of O 2 consumption in the exercising muscles, were slower in ilio-femoral vein obstruction (tau = 42±6 s), and PAD (tau = 49±19 s), compared to healthy participants (23±4 s; p<0.01)
CONCLUSIONS: Slow phase II V̇O 2 kinetics reflect a slow onset of muscular aerobic metabolism in both ilio-femoral vein obstruction and PAD. Low amplitude phase I of V̇O 2 kinetics observed in ilio-femoral vein obstruction suggests a damped cardio-dynamic phase, consistent with reduced venous return from the obstructed veins. These abnormalities of V̇O 2 kinetics may contribute to exercise intolerance in ilio-femoral vein obstruction and PAD.