Clinical Fetal Electrocardiography *

Interest in clinical fetal electrocardiography dates back to 1906 when Cremer4 published two tracings apparently showing fetal deflections of about 0.5 mm. amplitude superimposed on the maternal electrocardiogram of a nine-months gravid woman. The records were obtained with a string galvanometer electrocardiograph with one lead on the abdomen and one in the vagina. During the next 25 years Foa7 and Krumbhaar"4 each reported a similar result in a single case, while Sachs20 and Haynal and Kellner"0 admitted failure in their fairly extensive experiments. No further progress occurred until 1930 when Maekawa and Toyoshima"5 designed a valve amplifier which, when used with a string galvanometer, yielded an instrument with sufficient sensitivity to record the action current in excited nerve, and with this apparatus they obtained a fetal electrocardiogram by leading from the abdomen of a woman in labor. Their illustration is deficient in clarity, but it appears to reveal fetal waves of about 3 mm. amplitude. In 1938 Bell,2 working with an amplified thermionic valve electrocardiograph, obtained definite fetal deflections of several millimeters amplitude with abdominal leads in 10 of 35 women in the last two months of pregnancy. In the same year Johnson12 accidentally recorded tiny deflections, apparently of fetal origin, in the standard electrocardiogram of a woman at term. The amplification technics employed by Maekawa and Toyoshima and by Bell marked a distinct advance, but the character of the apparatus required was disadvantageous for the general application of the procedure. These widely scattered observations served at least to demonstrate that prenatal electrocardiography offered opportunity for further practical development. Until very recently, the chief work of clinical importance, as judged by the incidence of positive results, was that of Strassmann and his associates.24 25 26 27 They used an ordinary string galvan-