FETAL CARDIOVASCULAR HEMODYNAMICS IN THE PRESENCE OF COMPLETE ATRIOVENTRICULAR-BLOCK

OBJECTIVE: Our purpose was to follow serially the hemodynamic adaptati on to a congenital complete heart block in a human fetus. STUDY DESIGN : Longitudinal and serial M-mode and Doppler echocardiography over a 1 0-week span were performed on a fetus affected by complete heart block . Ventricular fractional shortening, size, and flow across the atriove ntricular valves and outflow tracts were determined starting at 20 wee ks up to the time of delivery. Neonatal Doppler follow-up was performe d at 2 days of life after implantation of a temporary pacemaker. RESUL TS: The right and left ventricles were able to adapt to sustained brad ycardia by increasing their size. This ventricular dilatation was also associated with an increase in fractional shortening, which was assoc iated with ventricular free wall hypertrophy. When ventricular heart r ate decreased to 38 beats/min, fractional shortening decreased, this w as associated with the rapid onset of ascites and pericardial effusion . CONCLUSION: In the presence of sustained bradycardia ventricular out put can increase, because this fetus was able to increase ventricular size and fractional shortening and wall thickness.