RT Book, Section A1 Kiefer, Todd A1 Granger, Christopher B. A1 Jackson, Kevin P. A2 Papadakis, Maxine A. A2 McPhee, Stephen J. A2 Rabow, Michael W. A2 McQuaid, Kenneth R. SR Print(0) ID 1193148457 T1 Cardiovascular Changes During Pregnancy T2 Current Medical Diagnosis & Treatment 2023 YR 2023 FD 2023 PB McGraw-Hill Education PP New York, NY SN 9781264687343 LK accessmedicine.mhmedical.com/content.aspx?aid=1193148457 RD 2024/03/29 AB Normal physiologic changes during pregnancy can exacerbate symptoms of underlying cardiac disease even in previously asymptomatic individuals. Maternal blood volume rises progressively until the end of the sixth or seventh month. Stroke volume increases over the same time course as a result of the volume change and an increase in LVEF. The latter reflects predominantly a decline in peripheral resistance due to vasodilation and the low-resistance shunting through the placenta. The heart rate then rises in the third trimester to further increase the cardiac output as the stroke volume maximizes out. Overall, cardiac output increases by 30–50%, peaking (and remaining constant) at about the 14th week; systolic BP tends to rise slightly or remain unchanged, but diastolic pressure falls significantly as afterload on the ventricle declines. Venocaval compression of the inferior vena cava from the gravid uterus can lead to reduced venous return and a lower cardiac output in the supine position.