![]() ![]() The responsiveness of veins to adrenergic stimulation is influenced by genetic factors. However, the research on the genetics of all these conditions has largely neglected the possibility that venous function may be an important intermediate phenotype. 5 A positive family history substantially increases the likelihood to suffer from varicose veins, 6 vasovagal syncope, 7 or essential hypertension. Indeed, ≈60% of the variation in the susceptibility to venous thrombosis is related to genetic factors. Thus, genes that influence venous function might play an important role in a variety of common cardiovascular ailments. 4 Venous function may also contribute to the pathogenesis of varicose veins, thrombophlebitis, and venous thrombosis. 3 Variability in the amount of blood that is pooled during standing influences the propensity to experience orthostatic symptoms. 1,2 Venous function becomes particularly important during assumption of upright posture as 500 to 1000 mL are pooled below the diaphragm. This mechanism may contribute to increased cardiac output in the earlier stages of essential hypertension. For example, an increase in venous tone may cause a shift of blood volume from the periphery toward the heart and increase cardiac output. Therefore, relatively small changes in venous function may have a substantial effect on the cardiovascular system. The genes involved may influence venous disease states.Īpproximately 75% of the circulating blood volume is contained in veins. The heritability estimate for venous compliance remained essentially unchanged after adjustment for sex and age.Ĭonclusions- We conclude that venous function is strongly influenced by genetic factors. The heritability estimate for venous capacity decreased to 0.3 after adjustment for age, body mass index, and body fat. ![]() Unadjusted heritability was 0.6 ( P<0.05) for venous capacity and 0.9 ( P<0.05) for venous compliance. Heritability was estimated using a path modeling approach. Venous compliance was determined as the steepest part of the venous pressure volume curve. In addition, we obtained venous pressure volume curves by slowly deflating a thigh cuff from 60 to 0 mm Hg. Venous capacity was determined by a standardized protocol. After a resting phase in the supine position, we determined venous function in both legs by impedance plethysmography. Methods and Results- We determined the heritability of venous function in 46 twin pairs (24 monozygotic, age 35☑1 years, 14 men, 34 women 22 dizygotic, age 30☘ years, 19 men, 25 women). Venous disease is presumably heritable however, the genetic variance of venous function is unknown. Objectives- Venous function contributes to the pathogenesis of thrombophlebitis, venous thrombosis, and possibly to arterial hypertension. Customer Service and Ordering Information.Stroke: Vascular and Interventional Neurology.Journal of the American Heart Association (JAHA).Circ: Cardiovascular Quality & Outcomes.Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB). ![]()
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