HEART DISEASES IN PREGNANCY
MODERATOR: PROF SUNIL AGARWAL
STUDENT: ANKIT KUMAR SAHU
Heart disease is the second most common cause of maternal death in Western countries, suicide being first1. According to CDC, heart disease is the leading cause of death in women who are 25 to 44 yrs old2. Maternal cardiac disease in a pregnant woman can present challenges in cardiovascular and maternal-fetal management thereby leading to significant non-obstetric maternal morbidity and mortality3. Approximately 1% of pregnancies are complicated by cardiac disease and the management of these cases can challenge the entire team providing care to the mother and fetus4. Women with congenital heart disease currently accounting for approximately 30-50% of all cardiac diseases in pregnancy5, now far outnumber those with rheumatic heart disease in pregnancy except in developing countries where 90% of all heart disorders in women of child-bearing age are of rheumatic origin. Advances in the treatment of congenital heart disease have made it possible for more affected children to reach adulthood and attempt pregnancy. Many women are postponing childbearing until the fourth and fifth decades of life6 and with advancing maternal age, underlying medical conditions such as hypertension, diabetes, and hypercholesterolemia the incidence of acquired heart disease complicating pregnancy is increasing7. The purpose of this article is to review the clinical features of incipient maternal cardiac disease and address recent advances in the management of these patients, and to consider the management of pregnant women known to have cardiac disease before delivery.
PHYSIOLOGICAL CARDIOVASCULAR ADAPTATION IN PREGNANCY
Pregnancy is associated with several cardiocirculatory changes that can significantly impact underlying cardiac disease. Knowledge of these cardiovascular adaptations is required to correctly interpret hemodynamic and cardiovascular tests in the gravida, to predict the effects of pregnancy on the woman with underlying cardiac disease, and to understand how the fetus will be affected by maternal cardiac disorders.
Hormonal changes, which relax smooth muscle, followed by formation of the placenta and foetal circulation, determine an increase in blood volume which starts to rise as early as the fifth week. Cardiac output is increased by as much as 30-50% during pregnancy. Capeless and Clapp8 have shown that almost half of this total increase takes place by 8 weeks and is maximized by mid-pregnancy. The early increase stems from augmented stroke volume that results from decreased systemic vascular resistance9. Later in pregnancy, resting pulse and stroke volume increase even more because of diastolic filling from pregnancy hypervolemia more so pronounced in multifetal pregnancy10. The heart rate rises by 10-30 beats per minute and cardiac output increases by 30% to 50% by the 32nd week of pregnancy11. Systolic blood pressure falls during the first half of pregnancy and returns to previous levels towards the end of pregnancy. The fall in blood pressure is usually 10 mmHg below baseline in the second trimester12, declining to a mean of 105/60 mmHg induced by a reduction in systemic vascular resistance, creation of a low-resistance circuit in the uteroplacental circulation13 and decreased vascular responsiveness to the pressor effects of angiotensin II and norepinephrine14. The possible role of humoral agents, such as vasodilator prostaglandins, estrogens, progesterone, and prolactin, in mediating the vasodilation remains to be established15. A rise in cardiac output is associated with an increased blood flow to the organs crucial in pregnancy, especially to the uterus. By the 10th week of gestation, uterine blood flow is 50 mL/minute; by term, it increases to 1200 mL/minute16,17. Blood flow to the kidneys is also increased by 30%, resulting in an increase in...
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