The clinician is often consulted to examine a pregnant woman for the presence of cardiovascular disease. Delineation of heart disease during pregnancy may be especially difficult, as the considerable hemodynamic changes that occur during normal pregnancy typically produce signs and symptoms that mimic cardiovascular disorders. Dyspnea, fatigue, palpitations, and chest discomfort are commonly described by normal pregnant women but are rarely of a severity to limit usual daily activities; syncope is a less frequent complaint.
Progressive augmentation of the resting cardiac output begins in the first trimester and increases to 30% to 50% above normal in the second and third trimesters. Although sodium and water retention partly explain these hemodynamic alterations, the effect of steroid hormones is thought to predominate; the placental low-resistance shunt is not considered a major factor. These features explain the frequent occurrence of peripheral edema, jugular venous distention with prominent neck vein pulsations, a prominent third
Wenger NK. The ECG in Normal Pregnancy. Arch Intern Med. 1982;142(6):1088-1089. doi:10.1001/archinte.1982.00340190044006