Certainly for clinical purposes, ventricular function during pregnancy is normal as estimated by the Braunwald ventricular function graph depicted in Figure 4-9 (p. 61). For given illing pressures, there is appropriate cardiac output so that cardiac function during pregnancy is eudynamic. In nonpregnant subjects with a normal heart who sustain a high-output state, the left ventricle undergoes longitudinal remodeling, and echocardiographic functional indices of its deformation provide normal values. In pregnancy, there instead appears to be spherical remodeling, and these calculated indices that measure longitudinal deformation are depressed. Thus, normal nonpregnant indices are likely inaccurate when used to assess function in studied, respectively. Moreover, a significant proportion of women studied demonstrated a drop in stroke volume index and a tendency toward eccentric remodeling. hese indings suggest cardiovascular maladaptation to the increased volume demands in a substantial proportion of apparently normal pregnancies. Of note, signiicant dyspnea at rest was reported by 7.4 percent of the women at term, most of whom had chamber diastolic dysfunction. Cardiac function and all signs of dyspnea fully recovered at 1 year postpartum.
Cardiac magnetic resonance (MR) imaging increasingly is used to evaluate cardiac structure and function. Stewart and associates (2016) performed cardiac MR imaging studies in 23 women longitudinally across pregnancy and at 12 weeks postpartum. Compared with studies performed at 12 to 16 weeks' gestation, left ventricular mass grew significantly for both normal-weight and overweight women. he calculated geometrical ratio of left ventricular mass to left ventricular end-diastolic volume demonstrated concentric remodeling throughout gestation, which resolved by 12 weeks' postpartum. he right ventricle also remodels (Martin, 2017) . Taken together, these observations likely mean that pregnancy causes a mixture of eccentric and concentric ventricular remodeling.
he physiological adaptations of normal pregnancy can induce symptoms and alter clinical indings that may confound the diagnosis of heart disease. For example, in normal pregnancy, functional systolic heart murmurs are common, respiratory efort is accentuated, edema frequently accrues in lower extremities after midpregnancy, and fatigue and exercise intolerance often develop. Some systolic flow murmurs can be loud, and normal changes in the various heart sounds depicted in
Figure 49-1 may erroneously suggest cardiac disease. In con trast, clinical findings that are more likely to suggest heart disease are listed in Table 49-2.
Noninvasive cardiovascular studies such as electrocardiography, chest radiography, and echocardiography will provide the data necessary for evaluation in most women.
In the electrocardiogram (ECG) , an average 15-degree leftaxis deviation is found as the diaphragm is elevated in advancing pregnancy. Other indings, depicted in Figure 49-2, include a reduced PR interval, inverted or flattened T waves, and a Q wave in lead DIll (Angeli, 2014). Pregnancy does not alter voltage indings. Atrial and ventricular premature contractions are relatively frequent (Carruth, 1981).
FIGURE 49-1 Normal cardiac examination findings in the pregnant woman. Sl = first sound; M1 = mitral first sound; S2 = second sound; P2 = pulmonary second sound. (Data from Gei, 2001; Hytten, 1991o.)
TABLE 49-2. Clinical Indicators of Heart Disease During Pregnancy �� +
Syncope Leftward deviation of the mean QRS axis .' I,,l,
Clubbing of fingers
Q wave in lead 0'1" (Reproduced with permission from Angeli F, Angeli E, Verdecchia P: Electrocardiographic changes in hypertensive disorders of pregnancy, Hypertens Res. 2014 Nov;37(11 ):973-975.) 0001 ...0001 ",'