[...]... of cyanotic heart disease, a decrease in afterload facilitates an increase in right-to-left intracardiac shunting, leading to increased cyanosis and hypoxemia As another example, changes in renal blood flow impacting on drug excretion and changes in the volume of distribution of drugs together explain in large part the need for modified drug dosing during pregnancy Anatomical changes during pregnancy The... of which increase during pregnancy (Figure 2.3) Cardiac output increases by about 30–50% ,10 ,11 ,16 ,17 ,22 with the first increase noted as early as week 5 of gestation and reaching a peak at approximately the end of the second trimester Physiological changes in pregnancy (b) 90 8 Stroke volume (mL) Cardiac output (L /min) (a) 11 7 6 5 80 70 60 4 P-P 5 8 12 16 20 24 28 32 36 38 PN P-P 5 8 12 16 20 24 28... al Longitudinal study of the renin–angiotensin– aldosterone system in hypertensive pregnant women: deviations related to the development of superimposed preeclampsia Am J Obstet Gynecol 19 90 ;16 3 :16 12– 21 31 Natrajan PG, McGarrigle HH, Lawrence DM, Lachelin GC Plasma noradrenaline and adrenaline levels in normal pregnancy and in pregnancy- induced hypertension Br J Obstet Gynaecol 19 82;89 :10 41 5 32 Davey... echocardiography during pregnancy: physiological and abnormal findings Echocardiography 19 96 ;13 :13 5–46 10 Clark SL, Cotton DB, Lee W, et al Central hemodynamic assessment of normal term pregnancy Am J Obstet Gynecol 19 89 ;16 1 :14 39–42 11 Robson SC, Hunter S, Boys RJ, Dunlop W Serial study of factors in uencing changes in cardiac output during human pregnancy Am J Physiol 19 89;256:H1060–5 12 Duvekot JJ, Cheriex... circulation, reaching up to 500 mL/min at term, measured in the supine position, and even higher in the left lateral decubitus position .13 Placental flow increases until week 25 of gestation and then remains unchanged In addition there is a fall in resistance caused by increased levels of peripheral vasodilators, in particular prostacyclin (PGI2) Renal blood flow increases during pregnancy, peaking in the third... (c) Heart rate (beats/min) 90 85 80 75 70 P-P 5 8 12 16 20 24 28 32 36 38 PN Gestation (week) Figure 2.2 Changes in cardiac output, stroke volume and heart rate during pregnancy P-P, prior to pregnancy; PN, postnatal – 6 months after delivery (Adapted from Robson et al .11 ) according to some (see Figure 2.2 )11 and later in the third trimester, according to others.23 Thereafter, cardiac output remains... Davey DA, Macnab MF Plasma adrenaline, noradrenaline and dopamine in pregnancy hypertension Br J Obstet Gynaecol 19 81; 88: 611 18 33 Yoshimura T, Yoshimura M, Yasue H, et al Plasma concentration of atrial natriuretic peptide and brain natriuretic peptide during normal human pregnancy and the postpartum period J Endocrinol 19 94 ;14 0:393–7 34 Borghi C, Esposti DD, Immordino V, et al Relationship of systemic... labour Br Med J (Clin Res Ed) 19 87;295 :11 69–72 38 Campos O Doppler echocardiography during pregnancy Echocardiography 19 96 ;13 : 13 5 14 6 Heart Disease in Pregnancy, Second Edition Edited by Celia Oakley, Carole A Warnes Copyright © 2007 by Blackwell Publishing CHAPTER 3 Cardiovascular examination in pregnancy and the approach to diagnosis of cardiac disorder Petros Nihoyannopoulos Pregnancy is a physiological... cardiac output increases progressively This increase is around 40–50% above the pre -pregnancy level and is maintained throughout pregnancy There is an accompanying decrease in vascular resistance, and diastolic and mean blood pressure In cyanotic or potentially cyanotic congenital heart disease, the drop in peripheral vascular resistance encourages right-to-left shunting, leading to increasing cyanosis,... 3000 2750 2500 2250 N-P 4 12 20 28 Gestation (week) 36 38 Red cell mass (mL) Plasma volume (mL) (a) 17 50 Treatment 15 00 12 50 10 00 No treatment N-P 4 12 20 28 Gestation (week) 36 38 Figure 2 .1 Changes in plasma volume and red cell mass during pregnancy N-P, not pregnant (Plasma volume data reproduced from Lind1 and Pirani et al.2 Red cell mass reproduced from Lind1 and Taylor and Lind.5) (b) The treatment . Cataloging -in- Publication Data Heart disease in pregnancy / edited by Celia Oakley, Carole A. Warnes. – 2nd ed. p. ; cm. Includes bibliographical references and index. ISBN -1 3 : 97 8 -1 -4 05 1- 3 48 8-0 . index. ISBN -1 3 : 97 8 -1 -4 05 1- 3 48 8-0 (hardcover) ISBN -1 0 : 1- 4 05 1- 3 48 8-7 (hardcover) 1. Heart diseases in pregnancy. I. Oakley, Celia. II. Warnes, Carole A. [DNLM: 1. Pregnancy Complications, Cardiovascular Mulder 11 Heart disease, pregnancy and systemic autoimmune diseases, 13 6 Guillermo Ruiz-Irastorza, Munther A Khamashta, Graham RV Hughes 12 Pulmonary disease and cor pulmonale, 15 1 Claire L Shovlin,