Many abnormalities are known to occur in the microcirculation in essential hypertension, including reduction in capillary density or rarefaction. Peripheral vasodilatation and angiogenesis are critical components of the physiological adaptation in normal pregnancy.
To investigate the hypothesis that defective angiogenesis, reflected in capillary rarefaction, may be implicated in the clinical syndrome of pre-eclampsia.
We used intravital capillary video-microscopy to study functional (baseline) and structural (after maximization with venous congestion) skin capillary density in 22 healthy normotensive pregnant women and compared our findings with those in 22 non-pregnant age-matched healthy controls and 11 women whose pregnancies were complicated by pre-eclampsia.
We found that both functional and structural capillary density increased during normal pregnancy. Capillary density in pre-eclamptic women was significantly lower both at baseline and after maximization. Skin capillary density appeared to be inversely correlated with blood pressure during pregnancy and in pre-eclampsia.
A low capillary density may account, in part, for the failure of blood pressure to decrease in pre-eclamptic pregnancies, and may reflect the maladaptive cardiovascular response that is part of the pre-eclampsia syndrome.
aClinical Pharmacology Unit, bDepartment of Obstetrics and Gynaecology and cBlood Pressure Unit, St George's Hospital Medical School, London, UK.
Sponsorship: These studies were supported by the Cardiovascular Research Trust. K.H., D.S. and T.A. are members of the St George's Cardiovascular Research Group. The Wolfson Foundation provided an Intercalated BSc project studentship to support Fu Siong Ng.
Correspondence and requests for reprints to Dr Isaac T. Manyonda, Department of Obstetrics and Gynaecology, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK. Tel: +44 020 8725 3663; fax: +44 020 8725 0078; e-mail: firstname.lastname@example.org
Received 7 February 2002 Revised 11 June 2002 Accepted 22 September 2002