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The venoarterial reflex
Suman Rathbun, P Jay Heath, Thomas Whitsett
To cite this version:
Suman Rathbun, P Jay Heath, Thomas Whitsett. The venoarterial reflex. Vascular Medicine, SAGE
Publications, 2008, 13 (4), pp.315-316. �10.1177/1358863X08092101�. �hal-00571383�
Images in vascular medicine
The venoarterial reflex
Suman Rathbun, P Jay Heath and Thomas Whitsett
The venoarterial reflex, or postural vasoconstriction reflex, is the decline in limb blood flow in the dependent position due to an increase in pre-capillary vascular resistance.1 Impairment of the venoarterial reflex may be a cause of unexplained leg swelling.
The venoarterial reflex prevents loss of fluid to the extravascular space when the legs are dependent. Test- ing of this reflex evaluates the ability of the cutaneous pre-capillary sphincters to constrict in response to depen- dency or elevated venous pressure and modulate the hydrostatic pressure.1The mechanism of this autoregu- lation is threefold: a local sympathetic axonal reflex, an
arteriolar-mediated myogenic response, and a minor central sympathetic efferent nerve component.1
The impaired venoarterial reflex may explain swelling in patients receiving calcium channel blockers.2 It is a cause of swelling in diabetics or patients with spinal degeneration that have neuropathy.3 It may explain edema in women during the luteal phase of their men- strual cycle.4 Attenuation of the reflex with higher skin temperatures may contribute to swelling experienced in hot climates.5
With the patient in a supine position, photoplethysmo- graphy (PPG) probes are applied to the great toe (Panel A) to monitor capillary flow at baseline showing normal amplitude pulsatile flow. One leg is then lowered 50 cm off the side of the exam table (Panel B). If the reflex is intact, there is an immediate reduction in the amplitude of the PPG pulsations (Panel C). If the reflex is absent or impaired, there will be no appreciable reduction in the pulsations (Panel D) compared to the supine leg position.
Treatment of leg swelling caused by an impaired venoarterial reflex is application of prescription knee length compression hose (20–30 mmHg) daily. Use of diuretics is minimally helpful. Evaluation of the venoar- terial reflex is an inexpensive, simple test for excluding this abnormality as a cause of otherwise unexplained leg swelling.
Panel A Panel B
University of Oklahoma Health Sciences Center, OU Vascular Center, Oklahoma City, Oklahoma, USA
Correspondence to: Suman Rathbun, Cardiovascular section, University of Oklahoma Health Sciences Center, 920 Stanton L. Young Blvd. WP 3120, Oklahoma City, OK 73104, USA.
Email: [email protected]
Panels A and B are available to view in color online at http://vmj.sagepub.com
Vascular Medicine2008;13:315–316
© 2008 SAGE Publications, Los Angeles, London, New Delhi and Singapore 10.1177/1358863X08092101
References
1 Hassan, A, Tooke, JE. Mechanism of the postural vasocon- strictor response in the human foot.Clin Sci1988;75: 379– 387.
2 Pedrinelli, R, Dell’Omo, G, Mariani, M. Calcium channel blockers, postural vasoconstriction and dependent oedema in essential hypertension. J Hum Hypertens2001;15: 455– 461.
3 Rayman, G, Hassan, A, Tooke, J. Blood flow in the skin of the foot related to posture in diabetes mellitus. Br Med J 1986;292: 87–90.
4 Hassan, A, Carter, G, Tooke, J. Postural vasoconstriction in women during the normal menstrual cycle.Clin Sci1990;78: 39–47.
5 Hassan, A, Tooke, J. Effect of changes in local skin temper- ature on postural vasoconstriction in man.Clin Sci1988;74: 201–206.
‘
Images in vascular medicine
’is a regular feature of
Vascular Medicine. Readers may submit original, unpublished images related to clinical vascular medicine to: Mark A Creager, Editor in Chief,
Vascular Medicine, Brigham and Women
’s Hospital, 75 Francis Street, Boston, MA 02115, USA.
Panel C
Panel D
316 S Rathbun et al.
Vascular Medicine2008;13:315–316
