Re: 'Post-LA space index' as a potential novel marker for the prenatal diagnosis of isolated total anomalous pulmonary venous connection

Fetal left-atrial posterior-space-to-diagonal ratio at 17-37 weeks' gestation for prediction of total anomalous pulmonary venous connection

OBJECTIVES

To develop normative data for the left-atrial posterior-space-to-diagonal (LAPSD) ratio and post-left atrium space (PLAS) index in fetuses from 17 to 37 weeks' gestation, and determine the optimal cut-offs of the LAPSD ratio and PLAS index to discriminate between normal fetuses and those with total anomalous pulmonary venous connection (TAPVC).

METHODS

This was a prospective cross-sectional assessment of 428 structurally normal fetuses between 17 and 37 weeks' gestation and a retrospective study of 27 TAPVC fetuses. The fetal LAPSD ratio was calculated by dividing the left atrium-descending aorta distance (LDD) by the left atrial diagonal diameter (LA). The PLAS index was calculated as the ratio of the LDD to the descending aorta diameter (DA). Pearson's correlation analysis was used to examine the correlation of cardiac parameters with gestational age (GA) and fetal somatic growth. The PLAS index and LAPSD ratio were compared between the normal and TAPVC groups to assess their usefulness in the prenatal diagnosis of TAPVC.

RESULTS

LDD, LA and DA measures showed moderate to strong positive correlation, whereas both the LAPSD ratio and PLAS index showed a slight decrease with increasing GA and biometric variables. The fetal LAPSD ratio and PLAS index in TAPVC cases were significantly greater compared with those of fetuses with a normal heart (both P < 0.001). There were no significant differences in the PLAS index and LAPSD ratio between the isolated and complex TAPVC groups (both P = 1). No significant associations of the PLAS index and LAPSD ratio with fetal gender, four-chamber view type (apical, basal or lateral) or TAPVC type were found. Using values of ≥ 0.35 for the LAPSD ratio and of ≥ 1 for the PLAS index exhibited similar excellent diagnostic performance, with a sensitivity of 100% and specificity of 97.0% or 95.1% for detecting TAPVC.

CONCLUSIONS

Our study demonstrates that the LAPSD ratio is a practical and effective screening tool for diagnosing fetal TAPVC, similar to the PLAS index. Incorporating these parameters into routine cardiac scanning may enhance the prenatal detection of TAPVC. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Post-Left Atrium Space Index in Fetuses With Total Anomalous Pulmonary Venous Connection and Other Congenital Heart Diseases

OBJECTIVES

We aimed to explore the value of the post-left atrium space (PLAS) index in the diagnosis of total anomalous pulmonary venous connection (TAPVC) and the effect of other congenital heart diseases on the PLAS index in the fetus.

METHODS

The PLAS index of 69 fetuses with TAPVC was analyzed retrospectively. Approximately 252 healthy fetuses were randomly selected as controls, and 110 cases of intracardiac malformations were randomly selected for comparison. The PLAS index was defined as the ratio of the left atrium-descending aorta distance divided by the descending aorta diameter from the 4-chamber view in the end-systolic phase.

RESULTS

There were no significant differences in the PLAS index among the 3 groups of isolated TAPVC subtypes (P > .05), or among the isolated TAPVC group and the simple and complex cardiac anomaly groups (P > .05). Compared with the control group, the PLAS index of the TAPVC group was significantly increased (P < .001). The PLAS index was significantly higher in the TAPVC group than in hypoplastic left heart syndrome, endocardial cushion defect, conotruncal defect, and ventricular septal defect groups (P < .05). The PLAS indices of the hypoplastic left heart syndrome, endocardial cushion defect, and conotruncal defect groups were all higher than that of the control group (P < .05). There was no significant difference in the PLAS index between the ventricular septal defect and control groups (P > .05).

CONCLUSIONS

The PLAS index is a sensitive parameter for the diagnosis of fetal TAPVC. There were no significant differences in the PLAS index among different TAPVC types. Complex intracardiac anomalies have an influence on the PLAS index.

Evaluation of the post-LA space index in the normal fetus

OBJECTIVE

We previously reported the post-LA space index (PLAS index), which is calculated as left atrial-descending aorta distance (LD) divided by the diameter of descending aorta (DA), could be useful for prenatal diagnosis of total anomalous pulmonary venous connection (TAPVC). In this study, we evaluated PLAS index in normal fetuses to assess its usefulness.

METHODS

In 304 normal fetuses, LD and DA were retrospectively measured, and the PLAS index was calculated. In 206 fetuses with data on the biparietal diameter (BPD) and femoral length (FL), the relationship between the PLAS index and them was investigated. We also calculated the PLAS index in 13 TAPVC fetuses.

RESULTS

Mean LD was 3.0+/-0.94 mm, mean DA was 4.8+/-0.87 mm, and the mean PLAS index was 0.62+/-0.19. DA and LD were correlated with gestational age (R = 0.52, 0.25), while the PLAS index showed little variation with gestational age (R < 0.2). BPD and FL were correlated with DA (R = 0.4, 0.42) but not with LD or the PLAS index (both R < 0.2). In the TAPVC fetuses, both LD and the PLAS index were significantly higher than in normal fetuses.

CONCLUSION

In normal fetuses, the PLAS index was independent of gestational age and fetal physique and may be useful for raising the suspicion of congenital heart disease, including TAPVC.