11. MEASURING ATRIOVENTRICULAR CONDUCTION IN THE FETUS USING TISSUE VELOCITY DOPPLER TECHNIQUE.

Principal investigators:
Rein AJJT, Sahn DJ, Geva T, Nir A.

Abstract:

Assessment of atrioventricular (AV) conduction in the fetus has been limited to detection of complete AV block. Precise measurement of fetal atrioventricular conduction time (AVCT) would be extremely valuable in maternal lupus erythematosus or to assess the effect of therapy for fetal arrhythmia. We have showed in a previous study that tissue velocity imaging (TVI) assesses AVCT accurately in the child and adult with excellent agreement with surface ECG PR interval.

Objectives

  • To study the feasibility of TVI in measuring AVCT in the fetus
  • To establish normal values for right and left AVCT
  • To assess the use of these normal values with a group of fetuses with prolonged AVCT
Subjects & Methods
The normal group comprised 28 normal fetuses (mean gestational age 21 weeks, range 16-32). Eight fetuses with long AVCT (7 fetuses with prolonged AVCT during atrial premature beats, 1 fetus on digoxin therapy) represented the diseased group. TVI was performed in the 4-chamber view using the GE Vingmed system V. TVI was performed at high frame rate (65-120, mean 78 Hz); cineloops of 3-9 cycles were stored as raw data for off-line analysis (Echopac 6.2). Simultaneous tissue velocity (TV) curves were obtained from 4 regions of interest: in the superior RA and LA, and in RV and LV myocardium at AV annulus level. AVCT was digitized from TVI curves from beginning of atrial contraction to onset of ventricular isovolumic contraction.
Results
Adequate TV images were obtained in 36/36 fetuses in 4 (2-5) minutes. AVCT was readily measured in all. In normal, the right AVCT (82±11 msec) was longer than left AVCT (71±12 msec;p>0.001). Stepwise regression analysis showed a correlation between right AVCT and gestational age (r=.65) but not with heart rate. The discrepancy between right and left AVCT was similar to that observed in our previous study in the child. Both right (122±17msec) and left (129±42msec) AVCT in the diseased group were significantly longer than the normal (p<0.001).

Status:
Preparing the manuscript