Heart during pregnancy

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Pregnancy is associated with hemodynamic and morphological changes of the cardiovascular system, in order to ensure adequate delivery of oxygenated blood of the fetus. These physiological changes are progressive during pregnancy trimesters and reversible in the post-partum period.

Changes involve circulating blood volume, peripheral vascular resistance, myocardial morphology and function and heart rate.[1]

Echocardiography is an important imaging tool in pregnant women with heart disease or cardiovascular symptoms like dyspnea, therefore knowing the normal changes is clinically important.

Contents

Hemodynamic and morphological changes during pregnancy

  • Progressive increase in blood volume, heart rate and stroke volume is noted during pregnancy, leading to an increased cardiac output
  • Cardiac output increases as early as 5 weeks of gestation [2]and an average 30-50% raise[3] is noted in the third trimester. Both increased heart rate and stroke volume contribute to this change.[2]
  • Systemic vascular resistance is decreased during pregnancy, with a nadir in the second trimester
  • Changes are more pronounced in twin pregnancies[2]
  • Increased preload leads to a mild increase in cavity dimensions and wall thickness, a pattern consistent with the development of eccentric hypertrophy, which is reversible post-partum

Echocardiographic changes during pregnancy

Doppler echocardiography changes

Continuous Wave Doppler

  • aortic and pulmonary peak velocities are increased as the result of the raised cardiac output. Aortic velocities as high as ~ 2m/s can be registered without any obstruction. Care should however be taken to exclude obstructive pathologies
  • mild elevation of tricuspid regurgitation peak velocity may be noted[4]

Pulsed Wave Doppler

  • time velocity integral of the aortic and pulmonary valve are increased
  • mitral inflow changes during pregnancy
  • E wave increases in the first trimester and remains at the superior end of normal range during pregnancy
  • A wave increases maximally in the third trimester
  • E/A is increased in early pregnancy and decreases afterwards due to A wave increase, with mean values of 1.3±0.2 in the third trimester[5]
  • E’ and A’ change in a similar manner
  • E/E’ shows no significant change during pregnancy[6]

Colour Doppler

  • mild mitral and tricuspid regurgitation are common during pregnancy

2D echocardiography

Extensive data regarding left ventricular remodeling during pregnancy is available from echocardiographic longitudinal studies. However, while changes are significant in a study group, their magnitude is relatively low and 2D values are usually within normal range.

  • Mild increase of ~ 5-10% in left-ventricular (LV) end-diastolic diameter and volume is detected.
  • LV wall thickness and mass increase. The relative wall thickness change is ~ 1mm in most studies, with values within normal range
  • Left atrium increases in size by 10-15%
  • Right atrium and right ventricle dimensions increase
  • The slight increase in mitral and tricuspid annulus explains the more frequent atrioventricular regurgitations
  • Mild pericardial effusions can be seen in late pregnancy with no pathological significance. Hemodynamic compromise due to pericardial effusion does not appear in normal pregnancies and in this case alternate etiologies must be considered[4]
  • Most studies report no significant changes of ejection fraction during pregnancy[7][8], although some found higher values during the first two trimesters[2] or lower values in the 38-40 weeks[9]


Peripartum cardiomyopathy is a rare but severe pregnancy complication presenting with heart failure and systolic dysfunction towards the end of pregnancy or in the months after delivery, with no other cause of heart failure. Diagnostic criteria require LV systolic dysfunction with LV ejection fraction<45% among other clinical criteria.[10] The echocardiographic appearance is tipically that of a dilative cardiomyopathy of any etiology, although LV might not be dilated in some cases.

Maternal conditions associated with high risk of cardiac complications during pregnancy[11]
NYHA class III or IV
Severe pulmonary hypertension
Severe mitral stenosis, severe aortic stenosis, severe native coarctation
History of peripartum cardiomyopathy with residual ventricular dysfunction
Marfan syndrome with aortic root or major valvular involvement

References

  1. Silversides C, Colman JM. Physiological changes in pregnancy. In Oakley C, Warnes C. Heart disease in pregnancy. 2nd Ed. Blackwell Publishing. 2007;6-18.
  2. 2.0 2.1 2.2 2.3 Hunter S, Robson S. Adaptation of the maternal heart in pregnancy. Br Heart J. 1992;68:540-543.
  3. Hagendorff A. Heart during Pregnancy. In Galiuto L, Badano L, Fox K, Sicari R, Zamorano JL. The EAE Textbook of Echocardiography. 1st edition. Oxford, Oxford University Press. 2011; 328-329.
  4. 4.0 4.1 Feigenbaum H, Armstrong WF, Ryan T. The heart in pregnancy. In: Feigenbaum H, Armstrong WF, Ryan T. Feigenbaum’s Echocardiography. 6th ed. Lippincott Williams&Wilkins. 2005;768-770.
  5. Mesa A, Jessurun C, Hernandez A, et al. Left ventricular diastolic function in normal human pregnancy. Circulation 1999; 99:511–517.
  6. Bamfo JE, Kametas NA, Nicolaides KH, Chambers JB.Maternal left ventricular diastolic and systolic long-axis function during normal pregnancy.Eur J Echocardiogr. 2007;8:360-368.
  7. Geva T, Mauer MB, Striker L, et al. Effects of physiological load of pregnancy on left ventricular contractility and remodeling. Am Heart J. 1997;133:53-59.
  8. Vlahović-Stipac A, Stankić V, Popović ZB, et al. Left ventricular function in gestational hypertension: serial echocardiographic study. Am J Hypertens. 2010;23:85-91.
  9. Estensen ME, Grindheim G, Remme EW, et al. Systemic arterial response and ventriculo-arterial interaction during normal pregnancy. Am J Hypertens. 2012 ;25:672-677.
  10. Elkayam U. Clinical characteristics of peripartum cardiomyopathy in the United States. J Am Coll Cardiol. 2011;58:659-670.
  11. Siu SC, Colman JM. Heart disease and pregnancy. Heart. 2001;85:710-715.

Further reading

  • Regitz-Zagrosek V, Blomstrom Lundqvist C, Borghi C, et al. ESC Guidelines on the management of cardiovascular diseases during pregnancy: the Task Force on the Management of Cardiovascular Diseases during Pregnancy of the European Society of Cardiology (ESC). Eur Heart J. 2011;32:3147-3197.
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