Pressure gradient and blood flow in human arm veins. -A proposed explanation of the pumping mechanism-.

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Abstract
In a patient with mitral stenosis a negative peripherocentral pressure gradient (P-C PG) was previously found despite a forward peripheral venous blood flow velocity (PVBFV) during supine leg exercise. The present study was undertaken to confirm this finding and elucidate its mechanism. In 6 patients with congestive heart failure, P-C PG was reversed from -2.4 to -18.7 cm H2O for 1-5 min during exercise. PVBFV, measured simultaneously with peripheral venous pressure (Pv) in 8 subjects, remained positive; 5 of these were patients with a negative P-C PG. The effect of i.v. lidocaine (1-26 mg) was studied in 13 patients: In 4 of 13 patients the change in Pv by saline injection was smaller than that after lidocaine (2-5 mg) injection (-0.5 .+-. 0.5, 3.9 .+-. 0.8 cm H2O, mean .+-. SE, respectively) (P < 0.02). In 13 patients Pv rose after a small dose of lidocaine. After a larger dose the rate of rise of Pv decreased or Pv dropped. No significant change was observed in the central venous pressure. In 6 patients who performed Valsalva''s maneuver, the rate of rise of Pv during the test decreased or unchanged after lidocaine injection. The probability of a pumping mechanism in superficial human arm veins was discussed.