Janet S. Kirk

Ultrasonographic left cardiac axis deviation: a marker for fetal anomalies.

Objective To determine if a relation exists between left cardiac axis deviation and fetal anomalies. Methods Estimation of cardiac examination in approximately 41,500 second- and third-trimester fetuses scanned between 1987–1993. Those with heart axes greater than 75° to the left were considered to have left axis deviation. Only cases with postnatal follow-up were included. Results Thirty-four fetuses with left cardiac axis deviation had postnatal follow-up; eight were normal and 26 abnormal (positive predictive value 76%). Twenty-one fetuses had cardiac abnormalities (ten of these had additional extracardiac findings), and five had extracardiac findings only. Conclusion Although left cardiac axis deviation can occur as an isolated sonographic finding in an otherwise normal fetus, most cases will demonstrate abnormalities of cardiac and/or extracardiac anatomy. Left cardiac axis deviation is largely associated with cardiac abnormalities, especially conotruncal anomalies, which may not be detectable by a four-chamber view alone. Therefore, the cardiac axis should be examined routinely as part of the four-chamber view of the fetal heart.

Fetal cardiac asymmetry : A marker for congenital heart disease

OBJECTIVE To determine the sensitivity of prenatally detected fetal cardiac asymmetry as a sonographic marker for congenital heart disease. METHODS The normal ratios of pulmonary artery to aorta diameters and of right ventricle to left ventricle diameters were derived from normal fetuses scanned at 17 weeks or more in a 65-month period. Cross-sectional diameters of cardiac ventricles and great arteries were measured at the level of the valves at the time of the scan. Fetuses with confirmed cardiac anomalies detected prenatally during the study were examined to identify how many had cardiac asymmetry, determined by abnormal ratios. RESULTS Linear regression analysis of the group of 881 normal fetuses showed the normal pulmonary artery to aorta diameter ratio remained constant throughout pregnancy and the normal right ventricle to left ventricle ratio increased slightly with progressing gestational age. The 90% confidence intervals were 0.79, 1.24 for the right ventricle to left ventricle ratio and 0.84, 1.41 for the pulmonary artery to aorta ratio. Of the 73 fetuses with abnormal hearts, 66% had either ventricular or great artery asymmetry (at least one of the two ratios was abnormal). However, if no asymmetry was present, the cardiac defect was more likely to be a minor one. CONCLUSION Cardiac asymmetry was present in two-thirds of fetuses with cardiac anomalies diagnosed prenatally. If cardiac asymmetry is found, a more thorough examination of the fetal heart is indicated.

Right Fetal Cardiac Axis: Clinical Significance and Associated Findings

Objective To ascertain the clinical significance of right fetal cardiac axis. Methods Fetal cardiac axis was assessed prospectively in ultrasound examinations of 16,562 fetuses over a 6-year period. Results Twenty-two fetuses had a right cardiac axis. When classified by ventricular and atrial configuration, six fetuses had mirror-image hearts with situs inversus, 12 had rotation of the heart axis alone, and four had inversion of the ventricles. Fourteen of the 22 had underlying structural cardiac defects, most of which were atrioventricular septal defects, double outlet right ventricles, or common atria. The chromosomes and/or phenotypes of all 22 were normal. All four fetuses with polysplenia and asplenia died. Major extracardiac defects were few (two) but lethal. Conclusion Right cardiac axis in the fetus is associated with a high incidence of structural cardiac defects. In the absence of severe extracardiac defects, polysplenia, or asplenia, neonatal outcome was good.

Interactive multimedia for prenatal ultrasound training

This demonstration project examines the utility of interactive multimedia for prenatal ultrasound training. A laser-disc library was linked to a three-dimensional (3-D) heart model and other computer-based training materials through interactive multimedia. A testing module presented ultrasound anomalies and related questions to house-staff physicians through the image library. Users were asked to evaluate these training materials on the basis of perceived instructional value, question content, subjects covered, graphics interface, and ease of use; users were also asked for their comments. House-staff physicians indicated that they consider interactive multimedia to be a helpful adjunct to their core fetal imaging rotation. During a 9-month period, 16 house-staff physicians correctly diagnosed 78 +/- 4% of unknown cases presented through the testing module. The 3-D heart model was also perceived to be a useful teaching aid for spatial orientation skills. Our findings suggest that interactive multimedia and volume visualization models can be used to supplement traditional prenatal ultrasound training. The system provides a broad exposure to ultrasound anomalies, increases opportunities for postnatal correlation, emphasizes motion video for ultrasound training, encourages development of independent diagnostic ability, and helps physicians understand anatomic orientation. We hypothesize that interactive multimedia-based tutorials provide a better overall training experience for house-staff physicians. However, these supplementary methods will require formal evaluation of effectiveness to better understand their potential educational impact.

Routine Measurement of Nuchal Thickness in the Second Trimester

Nuchal thickness was measured prospectively in all fetuses of 15 0/7 to 20 6/7 weeks scanned from January 1, 1988, to October 31, 1990. The most frequent indication for scan was gestational age. Of the 7,106 scans performed, 30 fetuses had an abnormal thickness of 6 mm or more. Twelve of the 30 had an abnormal karyotype: 9 with trisomy 21, 1 with triploidy and tetrasomy 12, 1 with partial trisomy 9, and 1 with trisomy 13 plus a 3,9 translocation. Two fetuses with normal karyotypes had another reason for nuchal thickening—Noonans syndrome in one and achondrogenesis in the other. Seven of the 18 fetuses who had a normal karyotype had an abnormal thickness measured at the upper end of the gestational age range between 20 0/7 and 20 6/7 weeks. Increased nuchal thickness is infrequently (0.4%) detected in the early second trimester and is associated with abnormal karyotypes (40%) and other anatomic findings. A nuchal thickness measurement should be part of every scan performed between 15 0/7 and 19 6/7 weeks,...

The significance of ultrasonographically diagnosed fetal wrist position anomalies.

OBJECTIVE Our purpose was to determine the clinical significance of ultrasonographically diagnosed fetal wrist position anomalies. STUDY DESIGN The relationship of the fetal hand to the forearm was prospectively evaluated in all second- and third-trimester scans over a 5-year period. If an abnormal wrist position was detected, a targeted scan, including echocardiography, was performed. The outcomes of abnormal pregnancies were obtained. RESULTS An abnormal relationship of the hand to the forearm was found in 22 fetuses in 27,467 scans. Nine had a normal karyotype, and 13 had an abnormal karyotype. Among the nine with normal chromosomes, three had evidence of a movement disorder. Three with normal karyotypes are alive; two of these are the only normally functioning survivors. They had no other major anomalies and were shown prenatally to have normal movement of the limbs. CONCLUSIONS An abnormal fetal wrist position is associated with a high incidence of karyotype and movement abnormalities.