Haberer K, Fruitman D, Power A, Hornberger LK, Eckersley L.Ultrasound Obstet Gynecol. 2021 Sep;58(3):405-410. doi: 10.1002/uog.23558.PMID: 33270293
Take Home Points:
- Among 51 fetuses with a “borderline LV”, 7 (13.7%) did not require any intervention at all, 39(76.4%) underwent biventricular repair and 5 (9.8%) underwent single ventricle palliation.
- Right to left flow at the FO predicts biventricular circulation.
- Among those with bidirectional or L to R flow at the FO, LV length z score < -2.4 and mitral valve z score < 4.5 after 27 weeks gestation predicted single ventricle palliation
- z scores may not be representative in SGA fetuses.
Commentary from Dr. Anna Tsirka (Hartford, CT, USA), section editor of Pediatric and Fetal Cardiology Journal Watch
One of the challenges in fetal cardiology is the prediction of postnatal outcome in the borderline left ventricle. A hypoplastic but apex forming LV with mild mitral or aortic valve hypoplasia has been referred to as the hypoplastic left heart complex (HLHC). These findings may be associated with biventricular (BV) circulation with coarctation of the aorta, may be associated with a left ventricle that is unable to support the systemic output, but at times may even represent a benign redistribution of flow that requires no intervention.
The primary aim of this study was to determine which echocardiographic features of HLHC in the fetal period are predictive of BV circulation.
This was a retrospective cohort study evaluating all echocardiograms performed at the University of Alberta Medical center between 2004 and 2017 with HLHC. Excluded were all infants with HLHS, conotruncal abnormalities, AV septal defects or primary abnormalities of the tricuspid valve.
The data from two separate time points in gestation were analyzed separately (18-26 weeks versus 27-36 weeks).
Data analyzed from fetal echocardiography included annulus dimension Z-scores of the MV, tricuspid valve (TV), pulmonary valve and AoV, TV:MV annulus dimension ratio, LV length (LVL) Z-score, LV and RV end-diastolic dimension Z-scores, LV:RV end-diastolic dimension ratio and direction of flow across the foramen ovale (FO) and the distal transverse aortic arch and isthmus.
Of the 76 fetuses that met inclusion criteria, 20 underwent termination of pregnancy, and 5 suffered IUFD. Of the remaining 51 patients, 7 did not require any intervention, 39 underwent biventricular surgical repair, and 5 underwent single ventricle palliation. 2 died after BV repair.
Predictors for BV circulation by univariate analysis at 18-26 weeks gestation were R to L or bidirectional flow across the foramen ovale (p 0.019), MV annulus Z-score (–2.91 vs –5.32 p 0.0003) and ascending aorta z score (-0.61 vs -3.24, p 0.009).
Predictors for BV circulation by univariate analysis at 27-36 weeks gestation were R to L or bidirectional flow across the foramen ovale (p 0.005), MV annulus Z-score (–3.5 vs –5.20 p0.003) while ascending aorta z score was no longer predictive. In those patients with echocardiograms in both time periods, the rate of change in LV length was also predictive of BV versus univentricular circulation.
On multivariate analysis MV annulus Z-score and right-to-left/bidirectional FO flow alone were predictive of BV circulation.
Left-to-right or bidirectional flow demonstrated the highest area under the ROC curve (0.90 (95% CI, 0.84–0.96)), with a sensitivity of 80% and specificity of 100%.
All cases with right-to-left FO flow achieved BV circulation. Among fetuses with bidirectional or left-to-right FO flow, a LVL Z-score of > –2.4 at 27–36 weeks and/or MV annulus Z-score of > –4.5 differentiated candidates for BV repair.
In long term follow up, 12 patients with BV circulation developed at least mild mitral stenosis (mean gradient > 5mmHg) and five patients developed isolated subaortic stenosis.
Fetal HLHC remains a prognostic challenge in fetal life and that makes counselling very difficult. Developing robust predictive criteria of BV versus univentricular repair is essential for effective counseling, especially given the fact that a significant portion of this population chooses to terminate the pregnancy based on our counseling.
In this study, all cases with right-to-left FO flow achieved BV circulation.
Among fetuses with bidirectional or left-to-right FO flow, a LVL Z-score of > –2.4 at 27–36 weeks and/or MV annulus Z-score of > –4.5 differentiated candidates for BV repair.
In seven cases surgery was not required at all. 4 of these were SGA. Regression of cardiac structures against gestational age may yield aberrant results in this context.
This is a retrospective study and evaluating these criteria prospectively would be a very interesting proposition.