Maternal Cardiovascular Physiology and Assessment

Maternal cardiovascular function changes dramatically in pregnancy with a first-trimester increase in heart rate, followed by a gradual reduction in vascular resistance and blood pressure, and compensatory increase in both intravascular fluid and cardiac output. Many techniques are now available for measuring cardiac output, vascular resistance, and arterial function including those based on bio-impedance, ultrasound, applanation tonometry, inert gas rebreathing, and Doppler, though there is no ‘gold standard’. The techniques are not interchangeable cross-sectionally, but can be used for serial assessments longitudinally in pregnancy. A knowledge of maternal cardiovascular physiology is essential in making sense of the changes that occur in pathological conditions of pregnancy.