[Electrocardiography, stress and the third pregnancy trimester]

Twelve patients whose ages ranged between 19 and 36 years, were studied. The gestational ages were between the 35th and the 39th week of pregnancy. The exercise performed was the one proposed by Kemp and Ellested. The analysis of the records comprised the electrocardiographic changes described by Dr. Chavez in his so called "syndrome of circulatory changes during pregnancy". Not all the characteristics were found in our cases, although this could be explained by the differences in the gestational age. The most common findings were the ST changes. In nine of our cases, they were more marked and appeared immediately after exercise and this makes us think that it could be due to the double load on the cardiac overload, that the exercise effects upon the cardiac muscle due to pregnancy. We could also advocate sympathetic and parasympathethic mechanisms, since in the final tracing this changes not only disappeared but were in some cases smoller than in the control. Regarding the cardiac rate it was found that it did not increase as shown in Robinson's Table. Nevertheless in eight cases, final tracings did not return to control levels and we could imply an "excess of heart rate" which is thought by Sheffield as a warning sign of coronary insufficiency. We will learn more about this after these same patients have had their-follow up studies when they are not pregnant. A larger series of cases is needed in the different trimesters of pregnancy as well as their reevaluation after the hormonal effects of pregnancy are over to ases the significance of this changes as well as their prognostic meaning during labor or as a warning sign of future coronary pathology.