Purpose: Congestive heart failure (CHF) is identified in the second and third trimesters of pregnancy as fetal hydrops and hydramnios. The occurrence of CHF has not been established in the first trimester. Endovaginally acquired pulsed (and tissue) Doppler are applied to evaluation of myocardial mechanics in early pregnancy.
Methods and Materials: Seven and/or 11 MHz endovaginal ultrasound imaging is performed in 1530 consecutive cases of intrauterine pregnancy 0.5 to 60 mm CRL with survival past 16 weeks GA, in 142 live cases with subsequent first trimester loss, and 476 cases in whom first trimester demise had occurred (missed abortion). Free amniotic fluid volume is calculated as the difference between gestational sac and fetal volumes. Heart rate is determined from 2 sec. intrathoracic pulsed Doppler. Doppler waveforms are classified as normal with regular occurrence of distinct ventricular filling and ejection phases (CRL>2.5 mm) and subclassified,independent of rate, as feeble, incomplete, or irregular.
Results: Heart rate increases by about 5 beats/min for each 1 mm growth in embryonic length, 0.5 to 20mm CRL. 109/142 subsequent loss cases had Doppler abnormalities, including all of the examples of relative bradycardia. The positive predictive value of normal pattern in 98% and the negative outcome predictive value of an abnormal Doppler is 99%. Free fluid volume in cases of missed abortion is larger than in cases with pregnancy continuation (p<.001).
Conclusion: Congestive heart failure is inferred during the embryonic period from increased free amniotic fluid volume and Doppler evidence of depressed myocardial contractility. CHF is a lethal occurrence in the first trimester, implicated in at least 40% of cases of missed abortion. It is to be hoped that identification of this mechanism of embryonic loss may elucidate etiology of this complication and enable new therapeutic possibilities.
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