Peripheral Vascular Surgery Society

#23 ALTERATIONS IN LOWER EXTREMITY VENOUS HEMODYNAMICS ASSOCIATED WITH NORMAL PREGNANCY.

Jeffrey L. Ballard, MD, Diane M. Papa, RVT, and Marie T. DeLange, RDMS

Loma Linda University Medical Center, Loma Linda, CA

Purpose: To define physiologic changes in lower extremity venous hemodynamics during healthy pregnancy.

Methods: Lower extremity venous physiology was evaluated using air plethysmography in 24 healthy primigravid females (48 extremities) with no known venous disease. All patients were studied during their first, second and third trimester, and at six weeks, three months and six months post-partum. Values for venous filling index, calf muscle pump function, residual volume fraction and venous outflow fraction were recorded for each limb. Data were evaluated for changes over time and for differences between the right and left lower extremity using repeated measures analysis of variance.

Results: None of the patients developed overt signs of venous reflux during pregnancy although there was an increase in venous filling index in advanced stages of pregnancy. All values remained within the normal range (1.0-1.7 ml./sec, p=0.52). Calf muscle pump function did not change appreciably during the study period (p=0.61). There was a statistically significant decrease in residual volume fraction that reached a nadir during the third trimester and returned to below-baseline values immediately post-partum (p=0.02). An increase in venous outflow fraction was demonstrated as pregnancy progressed (p=0.05). This trend peaked during the third trimester. During the study period, there was no difference between the right and left lower extremities with regard to venous filling index (p=0.25), calf muscle pump function (p=0.33), residual volume fraction (p=0.33) or venous outflow fraction (p=0.17).

Conclusions: Some alterations in venous hemodynamics are associated with pregnancy. Venous outflow fraction overall is increased coincident with a decrease in residual volume fraction. The significant decrease in residual volume fraction and augmentation in venous filling index may be related to an increase in venous capacitance secondary to hormonally influenced smooth muscle relaxation.

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Last updated January 1,2000