Flow analysis in the pulmonary trunc in fetuses with tetralogy of Fallot by colour Doppler flow mapping; two case reports

Subpulmonary stenosis assessed in midtrimester fetuses with tetralogy of Fallot: a novel method for predicting postnatal clinical outcome

This study aimed to determine whether quantification of subpulmonary stenosis (SPS) in tetralogy of Fallot (TOF) in the second-trimester fetus can predict postnatal clinical outcome measured by pulmonary valve size and/or timing or type of intervention. The study retrospectively identified fetuses with TOF from 1998 to 2010 diagnosed at 26 weeks gestation or earlier. The data evaluated included pre- and postnatal pulmonary valve z-scores (PVZ). To quantify fetal SPS, the authors created a novel index, the SPS/DAO ratio, a ratio of the minimum infundibular diameter to the descending aorta diameter (DAO). Multiple linear regression was used to predict postnatal PVZ from prenatally determined parameters, including SPS/DAO. Fetal parameters were analyzed by logistic regression for association with postnatal outcomes, namely, timing of surgery (<1 month), used as a surrogate for severity, and type of surgery [transannular patch (TAP) vs valve sparing surgery]. A total of 23 fetuses met the inclusion criteria. The mean gestational age was 21.8 ± 1.9 weeks (range, 16.6-25.4 weeks). There was excellent correlation between predicted and measured PVZ (r = 0.82; p < 0.0001) using the following derived equation: -3.68 + (0.91 × prenatal PVZ) - (4.44 × SPS/DAO) - 3.19 (prenatal PVZ × SPS/DAO). An SPS/DAO value lower than 0.5 had 100 % sensitivity and 56 % specificity for repair before the age of 1 month, and a value lower than 0.47 had 100 % sensitivity and 75 % specificity for TAP repair. Prenatal PVZ and the SPS/DAO ratio at 26 weeks gestation or earlier can reliably predict postnatal PVZ in fetuses with TOF. Quantification of SPS with the SPS/DAO ratio identifies patients who may require early intervention secondary to disease severity and may predict the type of repair, thereby influencing prenatal counseling.

Blood flow velocity waveforms of the fetal pulmonary artery and the ductus arteriosus: reference ranges from 13 weeks to term

OBJECTIVE

To establish reference ranges for blood flow velocity waveforms of the fetal main pulmonary artery and the ductus arteriosus during the second and third trimesters of pregnancy.

METHODS

A prospective cross-sectional echocardiographic study was performed in 222 normal fetuses from 13 to 41 weeks of gestation using high resolution/color Doppler ultrasound equipment.

RESULTS

Gestational age-specific reference ranges are given for peak velocity across the pulmonary valve, velocities in the ductus arteriosus, peak systolic velocity in the ductus arteriosus-to-peak velocity across the pulmonary valve ratio, ductal systolic velocity-to-diastolic velocity ratio, ductal resistance index and ductal pulsatility index. In the ductus arteriosus, increasing fetal heart rate was significantly associated with increasing end-diastolic velocity and decreasing systolic-to-diastolic ratio, decreasing resistance index, and decreasing pulsatility index.

CONCLUSIONS

Based on a prospective study in more than 200 normal fetuses, the data provide gestational age specific reference ranges for blood flow velocity waveforms of the fetal pulmonary artery and the ductus arteriosus. The reference ranges may be helpful in prenatal diagnosis of cardiac malformations and ductal obstruction from 13 to 41 weeks of gestation.

Prenatal diagnosis of tetralogy of Fallot with absent pulmonary valve and aortic stenosis

The association of tetralogy of Fallot with absent pulmonary valve and aortic stenosis is extremely rare. In this report the prenatal diagnosis of this anomaly was made in a 28-year-old woman at 31 weeks' gestation.

Reversed shunting across the ductus arteriosus or atrial septum in utero heralds severe congenital heart disease

OBJECTIVES

This study was performed to define the significance of Doppler color flow mapping in demonstrating reversal of the direction of the normal physiologic flow across the atrial septum and ductus arteriosus in the human fetus.

BACKGROUND

Reversal of the physiologic shunting across the ductus arteriosus or atrial septum in utero (i.e., left to right) can be readily identified by Doppler color flow mapping, complemented by pulsed and continuous wave Doppler information.

METHODS

We reviewed echocardiograms recorded at our three institutions from 1988 to 1993, which displayed reversal of flow by Doppler color flow in 53 fetuses of gestational age 18 weeks to term. The diagnoses were confirmed by postnatal echocardiography, operation or autopsy. Reversal of shunting was consistently associated with severe heart disease.

RESULTS

Reversed atrial shunting was found with severe left heart obstructive lesions, including 19 with hypoplastic left heart syndrome, 3 with critical aortic stenosis, 2 with double-outlet right ventricle and 1 each with an interrupted aortic arch, atrioventricular septal defect and severe left ventricular dysfunction due to dilated cardiomyopathy. Reversed ductus arteriosus shunting was found with severe right heart obstructive lesions, including nine fetuses with pulmonary atresia, six with severe obstructive tricuspid valve abnormalities, five with severe tetralogy of Fallot, four with Ebstein's anomaly and two with single ventricle and pulmonary stenosis. Associated cardiac lesions were common in both groups. Only 3 of the 15 infants who were delivered alive from the reverse ductus arteriosus shunt group and 4 of 12 from the reverse atrial shunt group still survive.

CONCLUSIONS

The finding of reversed flow by Doppler color flow mapping during fetal life provides a key to subsequent accurate diagnosis and denotes a spectrum of diseases with a very poor prognosis.

In utero pulmonary artery and aortic growth and potential for progression of pulmonary outflow tract obstruction in tetralogy of Fallot

OBJECTIVES

This study was designed to define patterns of pulmonary artery and aortic growth in fetuses with tetralogy of Fallot and to determine the potential for in utero progression of right ventricular outflow tract obstruction.

BACKGROUND

Despite an abundance of reports documenting the prenatal diagnosis of tetralogy of Fallot, there is little information about its course in utero.

METHODS

Pulmonary artery and ascending aortic diameters were measured from prenatal and postnatal echocardiograms of 16 fetuses with tetralogy of Fallot, initially studied at 23.6 +/- 6.0 (mean +/- SD) weeks of gestation. Fetuses were classified retrospectively as having mild and severe tetralogy of Fallot according to whether the pulmonary artery circulation was (severe, n = 5) or was not (mild, n = 11) ductus arteriosus dependent at birth.

RESULTS

Initial main pulmonary artery diameter was small for gestational age in 9 fetuses, large in 2 and normal in 5 compared with data from 57 gestational age-adjusted normal fetal studies; it was significantly smaller in the group with severe tetralogy of Fallot (p = 0.05). The initial main pulmonary artery/aortic diameter ratio was also smaller for the group with severe tetralogy of Fallot (0.50 +/- 0.15 vs. 0.73 +/- 0.14 in the group with mild tetralogy of Fallot, p = 0.01). Initial aortic and branch pulmonary artery diameters tended to be normal or near normal for age. In eight fetuses serially studied, main and branch pulmonary artery growth was normal or reduced during prenatal follow-up. Pulmonary artery growth was most reduced in two fetuses in the group with severe tetralogy of Fallot, resulting in pulmonary artery hypoplasia at birth. Two fetuses with valvular pulmonary atresia at birth had previously shown anterograde pulmonary outflow in midgestation, suggesting progression of pulmonary outflow obstruction.

CONCLUSIONS

The postnatal spectrum of pulmonary artery size in tetralogy of Fallot can be attributed to variable patterns of growth in utero. Main pulmonary artery size, main pulmonary artery/aortic diameter ratio and pattern of pulmonary artery growth may be predictive of the severity of postnatal pulmonary outflow obstruction. Pulmonary atresia can develop in utero in some fetuses with tetralogy of Fallot.