Pregnancy is associated with dramatic changes in the cardiovascular system that may result in significant he modynamic stress to the patient with underlying heart disease.
During a normal pregnancy, plasma volume increases an average of 50%, beginning in the first trimester and peaking between the 20th and 24th weeks of pregnancy.
This change is accompanied by an increase in stroke volume, heart rate , output. In addition, there is a concomitant fall in systemic vascular resistance and mean arterial pressure cause of the effects of gestational hormones on the vasculature and the creation of a low-resistance circulation in the pregnant uterus and placenta. During labor, uterine contractions result in a transient increase of up to 500 mL of blood into the central circulation, resulting in a further increase in stroke volume and cardiac output. After delivery, intravascular volume and cardiac output increase further as compression of the inferior vena cava by the gravid uterus is relieved and extravascular fluid is mobilized. Symptoms and signs that may mimic cardiac disease often accompany these hemodynamic changes and include fatigue, reduced exercise tolerance, lower extremity edema, distention of the an S3 gallop and new systolic murmurs . Differentiating symptoms from cardiac disease versus those attributable to a normal pregnancy can be difficult. Many pregnant patients with known cardiac disease can complete a and delivery without to the mother or However, certain cardiac conditions, including irreversible pulmonary hypertension, cardiomyopathy associated with severe heart failure, and symdrome with a dilated aortic root, are associated with a high risk for cardiovascular complications and death.
Under these circumstances, patients should be advised against having children. If pregnancy should occur, a first-trimester therapeutic abortion should be strongly recommended.