Atrial dominance in the human embryonic heart: a study of cardiac function at 6-10 weeks of gestation.

OBJECTIVE: To investigate the difference in forces developed by atrial and ventricular myocardium during contraction in human embryos using a novel method. METHODS: This was a cross-sectional study of 115 pregnancies examined at 6-10 weeks of gestation. Ventricular inflow and outflow velocities were obtained by Doppler echocardiography and the relative force development was evaluated by calculating the ratio between atrial and ventricular ejection force (EF). RESULTS: Data from 97 embryos with monophasic ventricular filling were analyzed. Both inflow and outflow cardiac velocities increased with advancing gestational age (P < 0.001). The mean peak inflow velocity (31.7 ± 10.2 cm/s) was significantly higher (P < 0.0001) than the outflow velocity (19.6 ± 6.1 cm/s). The EFinflow /EFoutflow ratio was more than 1.0 in all but four (96%) cases. CONCLUSION: Our study indicates the possibility of atrial dominance in the embryonic period of heart development, which may have clinical implications, as deviations from this normal pattern may indicate human embryonic cardiac dysfunction.

Comparison between pulsed-wave Doppler- and tissue Doppler-derived Tei indices in fetuses with and without congenital heart disease.

OBJECTIVES: The aim of this study was to compare the right (RV) and left (LV) ventricular Tei indices obtained by pulsed-wave Doppler (PD) and tissue Doppler (TD) methods in fetuses with structurally normal and abnormal hearts. METHODS: This was a retrospective cross-sectional study of 147 fetuses that had a fetal echocardiogram and Tei index measured during a 2-year period. The RV and LV Tei indices were measured using both PD and TD methods. The difference between the two methods of Tei index measurement was tested using paired sample t-test, Pearson correlation coefficient was used to examine their relationship, and the agreement between the methods was tested using Bland-Altman analysis. RESULTS: A total of 87 fetuses had normal hearts and 60 had a congenital heart defect. Both PD and TD Tei indices were measured successfully from at least one ventricle in 123 cases and from both ventricles in 110 cases. The mean TD Tei index was significantly higher than the mean PD Tei index for both ventricles (P < 0.0001). There was a weak but statistically significant correlation between the PD and TD Tei indices of the right ventricle (r = 0.20, P = 0.029), whereas the PD and TD Tei indices of the left ventricle did not correlate significantly (r = 0.04, P = 0.684). When pairs of Tei indices measured by two different methods (123 pairs for the right ventricle and 111 for the left ventricle) were tested with Bland-Altman analysis, the bias and precision were 0.147 and 0.254, respectively, for the right ventricle, and 0.299 and 0.276, respectively, for the left ventricle. CONCLUSIONS: Correlation between Tei indices measured by PD and TD methods is weak and the agreement between individual measurements is poor. Therefore, they should not be used interchangeably in the assessment of fetal cardiac function.

Doppler study of the embryonic heart in normal pregnant women.

OBJECTIVE: To describe normal fetal cardiac and hemodynamic development in normal early first trimester pregnancies. MATERIALS AND METHODS: Eighty-eight women with singleton, uncomplicated pregnancies were prospectively studied with transvaginal ultrasound, pulsed and color Doppler. Heart diameter, heart rate, and inflow and outflow waveforms with valve signals were documented. The proportion of the cardiac cycle of isovolumetric relaxation time (IRT%) and isovolumetric contraction time (ICT%) as well as Tei index were calculated. RESULTS: Ninety-one percent of studies were successful. Heart diameter and the fetal heart rate showed a positive correlation with increasing gestational age: R = 0.80 (p < 0.000001), R = 0.76 (p < 0.000001), respectively. Mean heart diameter at 6 weeks was 1.28 +/- 0.26 mm and mean fetal heart rate was 117 +/- 6 bpm compared to 3.88 +/- 0.54 mm and 171 +/- 6 bpm at 10 weeks. The inflow waveform was monophasic (atrial contraction) in all cases from 6 to 9 weeks. Eight pregnancies (9%) miscarried between 6 and 12 weeks of gestation and the heart exams were characterized by increased IRT% compared with the survivors. In survivors, IRT% decreased between 7 and 8 weeks, from 32.9 +/- 10.7% to 20.8 +/- 5.7% (p < 0.0001). ICT% decreased from 18.6 +/- 4.4% of the cardiac cycle at 8 weeks to 12.6 +/- 4.4% at 9 weeks (p < 0.0008) (after heart development period). CONCLUSIONS: Doppler examination of the fetal cardiac function is possible after 5 weeks of gestation. After 8 weeks of gestation, the fetal heart is morphologically mature but has not yet achieved effective myocardial compliance. The embryonic human heart is dependent on the atrial contraction for ventricular filling throughout the period of cardiac development. Non-survivors manifest myocardial dysfunction.

First trimester screening for congenital heart disease.

Most obstetrical practices in the United States offer pregnant women at least one ultrasound during pregnancy. This prenatal ultrasound is usually scheduled at around 18 to 20 weeks gestation. Both the American Institute of Ultrasound in Medicine and the American College of Obstetricians and Gynecologists recommend that the four-chamber view be included to screen for congenital heart disease. Recently, many investigators have attempted to screen for congenital heart disease earlier in pregnancy. Fetal nuchal translucency thickness traditionally used to screen for fetal aneuploidy by transvaginal and abdominal ultrasound has also been shown to identify a large proportion of fetuses with congenital heart disease. Recent studies have also reported congenital heart disease in chromosomally normal fetuses with increased nuchal translucency thickness in the first trimester. Advances in ultrasound technology and training over the last 10 years allow greater visualization rates of the four-chamber view and outflow tracks in the late first trimester (up to 90% visualization at 13 weeks). Fetal echocardiography in the first trimester may be indicated for fetuses at risk for congenital heart disease. In this article we present a review of the most recent and ongoing clinical and basic research to support an earlier first trimester approach to diagnosing congenital heart defects.

Cardiac septation in atrioventricular canal defect.

To determine the relative contributions of the atrial and ventricular septa to total cardiac septation in patients with atrioventricular (AV) canal defect, two-dimensional echocardiography was used to measure the length of each portion of the septum in 14 patients with partial AV canal and 13 patients with the complete form of this lesion. Results were compared with similar data from 30 normal children, 10 patients with dilated cardiomyopathy and 11 patients with ostium secundum atrial septal defect. In patients with partial AV canal, the portion of total cardiac length occupied by the atrial septum did not differ from normal (24.8 +/- 9.9% versus 28.7 +/- 7.9%, p greater than 0.05), but there was a deficiency of both AV and ventricular septal tissue, the latter occupying only 48.2 +/- 7.0% of total cardiac length (versus 57.9 +/- 4.1% in normal subjects, p less than 0.05). Similarly, patients with complete AV canal had a normal amount of atrial septal tissue, a deficiency of AV septal tissue and a deficiency of ventricular septal tissue which was even greater than that of patients with a partial defect (39.4 +/- 5.0% versus 48.2 +/- 7.0%, p less than 0.05). Thus, although partial AV canal defect is often called ostium primum atrial septal defect, the amount of atrial tissue is usually normal, the defect being formed by a deficiency of AV and ventricular septal tissue. In the complete form of the lesion, the deficiency of ventricular septal tissue is greater.

Patency of the ductus arteriosus in normal neonates: two-dimensional echocardiography versus Doppler assessment.

Two-dimensional echocardiography using a high resolution, 7.5 ,Jsz transduce was compared with Doppler echocardiography for the assessment of patency of the ductus arteriosus in normal newborn infants. Twenty-eight neonates were studied between 1 and 10 hours (mean 5.5) after birth and both examinations were possible in 27 (96%). Doppler echocardiography under two-dimensional direction indicated ductal patency in all 27 neonates. Doppler sampling in the pulmonary end of the ductus rather than the main pulmonary artery was more sensitive for detecting patency. When two-dimensional echocardiography only was used to predict patency, there was 85% sensitivity. Two-dimensional echocardiography showed no evidence of ductus arteriosus narrowing ion four neonates studied shortly after birth. In 18, the pulmonary portion of the ductus arteriosus appeared narrowed and in 8 of these, the narrowing extended toward the mid-portion of the ductus. In five others, there was only mid-ductus arteriosus narrowing. It is concluded that high resolution two-dimensional echocardiography can be used to assess ductus arteriosus morphology, but is limited in predicting ductal patency near the time of normal physiologic closure. Combined two-dimensional and Doppler echocardiography is a highly sensitive technique for detection of ductal patency when sampling is performed in the pulmonary end of the ductus arteriosus.

Two-dimensional echocardiographic assessment of pulmonary artery and aortic arch anatomy in cyanotic infants.

To determine the feasibility and accuracy of noninvasive assessment of pulmonary artery and aortic arch anatomy, a prospective two-dimensional echocardiographic evaluation was performed in 20 consecutive cyanotic infants before cardiac catheterization and angiography. The echocardiographic assessment was correct with the following frequency: detection of left aortic arch in 13 of 13 infants, detection of right aortic arch in 7 of 7, identification of patent ductus arteriosus in 13 of 13 (one false positive finding), identification of a right pulmonary artery in 20 of 20, identification of a left pulmonary artery in 19 of 20, identification of the confluence of the right and left pulmonary arteries in 19 of 20 and identification of a main pulmonary artery in 14 of 16 (two false positive diagnoses by echocardiography). Echocardiographic estimates of arterial diameters were slightly smaller than those obtained by angiography. Mean vessel size (echocardiographic/angiographic diameter) was as follows: transverse aortic arch 8.6/10.6 mm, main pulmonary artery 5.7/6.3 mm, right pulmonary artery 4.1/4.2 mm and left pulmonary artery 4.2/3.9 mm. It is concluded that although two-dimensional echocardiography tends to underestimate vessel size, the qualitative assessment is adequate for planning a systemic to pulmonary artery anastomosis in selected infants with cyanotic forms of congenital heart disease.

Two-dimensional echocardiographic diagnosis of anomalous origin of the right pulmonary artery from the aorta: differentiation from aortopulmonary window.

Utilizing two-dimensional echocardiography, the diagnosis of anomalous origin of the right pulmonary artery from the aorta was made prospectively in a neonate who presented with signs of congestive heart failure. A complete echocardiographic evaluation, including both right parasternal short-axis and suprasternal long-axis scans, permitted differentiation from other defects in aortopulmonary septation.

Assessment of the ductus arteriosus in preterm infants utilizing suprasternal two-dimensional/Doppler echocardiography.

Evaluation for patent ductus arteriosus by both Doppler examination and direct two-dimensional echocardiographic visualization has been reported in infants and children. However, visualization of a patent ductus arteriosus in preterm infants with lung disease has been difficult. Using a recently developed 7.5 MHz mechanical scanner with interfaced two-dimensional directed pulsed Doppler ultrasonography, 36 examinations were performed from a suprasternal approach in 27 patients (age range 1 day to 3 months, mean 18 days; weight range 490 to 2,500 g, mean 1,260). Complete imaging for evaluation of patency of the ductus arteriosus was successful in 33 (92%) of 36 examinations, and imaging of the pulmonary end of the ductus arteriosus was successful in all. In 18 examinations, the ductus arteriosus was closed by both two-dimensional echocardiography and Doppler examination. In four cases the ductus arteriosus was widely patent by both two-dimensional echocardiography and Doppler examination. Eleven echocardiographic examinations revealed a narrowed ductus arteriosus, and of these, 10 (91%) showed Doppler findings of patent ductus arteriosus. It is concluded that combined two-dimensional/Doppler echocardiographic assessment allows confident detection of both a large unrestrictive and a small, stenotic patent ductus arteriosus in preterm infants with lung disease.

Quantitative morphology of the aortic arch in neonatal coarctation.

It has been speculated that neonatal coarctation results from postnatal constriction of the aortic isthmus and ductus arteriosus. However, aortic arch hypoplasia is present in some neonates with coarctation and is presumed to be due to decreased aortic arch blood flow in utero. To measure the degree of aortic arch hypoplasia and to analyze the distribution of blood flow in neonatal coarctation, quantitative morphometric analysis of the great vessels from two-dimensional echocardiograms was performed in 14 neonates with isolated coarctation and 14 normal control neonates, all less than 1 month old. Measurements of the aortic valve, pulmonary valve, ascending aorta, transverse aortic arch between the carotid and subclavian arteries, aortic isthmus, descending aorta, main pulmonary artery and brachiocephalic vessels were obtained to the nearest 0.5 mm. In coarctation patients the transverse arch and isthmus were significantly smaller than in control subjects (p less than 0.001). In addition, pulmonary valve and main pulmonary artery diameters were significantly greater in neonates with coarctation than in normal neonates. Transverse arch hypoplasia and increased pulmonary valve and pulmonary artery diameters are present in neonates with coarctation. This suggests decreased aortic arch flow and increased pulmonary and ductus arteriosus flow in utero, which produce a characteristic echocardiographic appearance of transverse arch hypoplasia with a large main pulmonary artery.

Hypoplastic left heart syndrome: is echocardiography accurate enough to guide surgical palliation?

Two-dimensional echocardiography can diagnose hypoplastic left heart syndrome. However, with the advent of the possibility of palliative open heart surgery, complete anatomic diagnosis is necessary. The anatomic findings of 15 neonates with hypoplastic left heart syndrome (age 1 to 10 days, mean 4.1) who had two-dimensional Doppler echocardiographic studies were compared with the results obtained by angiography (6 cases), surgery (11 cases) and autopsy (8 cases). Complete two-dimensional echocardiographic examination of the aortic arch, pulmonary and systemic venous return, atrial septum, ductus arteriosus and proximal coronary arteries was possible in all 15 neonates and correctly diagnosed hypoplastic left heart syndrome in each. Anatomic two-dimensional echocardiographic assessment was accurate in 13 (86%) of the 15 neonates and there were no false positive results. Undiagnosed associated abnormalities were hypoplasia of a left pulmonary artery in one patient and left superior vena cava in another. Accurate quantitation of the size of the tricuspid valve anulus, ascending aorta, pulmonary anulus and right and left pulmonary arteries was possible. Doppler examination was performed in seven patients and confirmed retrograde aortic arch flow and right to left systolic shunting in the patent ductus arteriosus. In selected neonates, surgical palliation can be attempted without angiography.

Doppler echocardiography of fetal ductus arteriosus constriction versus increased right ventricular output.

A prospective longitudinal study from 121 examinations of 41 normal pregnant women showed that fetal ductal flow velocities increased with gestational age. These normal data were compared with data in three groups of fetuses with altered ductal flow velocities: 22 fetuses (mean gestational age 31.3 weeks) had ductal constriction due to maternal indomethacin treatment; 10 fetuses (mean gestational age 27.9 weeks) had been exposed to terbutaline, a positive inotropic agent and 14 fetuses (mean gestational age 33.3 weeks) had hypoplastic left heart syndrome. In normal fetuses maximal systolic, mean and end-diastolic ductal flow velocities increased linearly (p less than 0.0001). The pulsatility index did not change (mean +/- 2 SD: 2.46 +/- 0.52). Fetuses with ductal constriction had higher maximal, mean and end-diastolic flow velocities and a significantly lower pulsatility index than did normal fetuses (1.25 +/- 0.76; p less than 0.0005). Six of 10 fetuses of the terbutaline group and 8 of 14 fetuses with hypoplastic left heart syndrome had increased maximal flow velocity, but normal or only mildly elevated mean flow velocity. The pulsatility index in fetuses during terbutaline therapy and with hypoplastic left heart syndrome was significantly higher than in normal fetuses (3.11 +/- 0.46 and 3.09 +/- 0.7, respectively, vs. 2.46 +/- 0.52; p less than 0.0005). Fetal ductal waveform analysis was necessary to distinguish fetal ductal constriction from increased right ventricular output. These measurements may be helpful in the diagnosis of left-sided outflow obstruction and assessment of fetal hemodynamic data.

Doppler echocardiography in the diagnosis and management of persistent fetal arrhythmias.

Thirteen fetuses with persistent arrhythmias underwent combined noninvasive echocardiographic evaluation utilizing M-mode, two-dimensional and pulsed Doppler echocardiography. This group (Group A) was compared with 14 fetuses in which only two-dimensional and M-mode echocardiographic evaluations were performed (Group B). In both groups correct prenatal interpretation of the arrhythmia was confirmed by postnatal electrocardiograms in all surviving fetuses. Although Doppler echocardiography was not more sensitive than M-mode echocardiography in the interpretations of the arrhythmia, Doppler tracings of sufficient quality to analyze rate and rhythm were easier to obtain in all cases and provided additional information about valvular incompetence and the functional state of the fetal heart. Cardiac malformations and hydrops fetalis were commonly associated with persistent arrhythmias. Congenital heart disease occurred frequently (6 of 11) with complete atrioventricular (AV) block. Pulsed Doppler echocardiography defined the AV contraction sequence, atrial and ventricular rates and AV valve insufficiency, allowing rapid interpretation of fetal arrhythmias.

Two-dimensional echocardiographic spectrum of univentricular atrioventricular connection.

The spectrum of anomalies in hearts having a univentricular atrioventricular (AV) connection was examined by two-dimensional echocardiography in 183 patients and the anatomic findings were compared with angiography. The mode of AV connection was found to be of three types: double inlet via two AV valves; single inlet via one AV valve with absence of the other (left or right AV valve atresia); and common inlet via a common AV valve. Identification of an accessory chamber by two-dimensional echocardiography was possible with 90% sensitivity, but it was limited compared with angiography in patients with severely hypoplastic anterior chambers and pulmonary valve atresia. All patients with subaortic outlet foramen obstruction were detected. Great artery position and the presence of obstruction to pulmonary flow were correctly predicted in all but one patient. Two-dimensional echocardiography was superior to angiography for the detection of AV valve abnormalities which were present in 27% and included abnormal chordae, hypoplasia or dysplasia of either valve. Two-dimensional echocardiography should play an essential role in the complete preoperative assessment of patients with univentricular AV connection.

Aortico-left ventricular tunnel with ventricular septal defect: two-dimensional/Doppler echocardiographic diagnosis.

Aortico-left ventricular tunnel is a rare congenital anomaly that presents as aortic regurgitation and congestive heart failure in childhood. Its association with a ventricular septal defect is even more rare. Because of the distortion of the normal anatomy around the aortic valve and the rarity of this combination of defects, the diagnosis of aortico-left ventricular tunnel with ventricular septal defect may be difficult. The two-dimensional and Doppler echocardiographic findings of aortico-left ventricular tunnel are described.

Pulmonary venous and systemic ventricular inflow obstruction in patients with congenital heart disease: detection by combined two-dimensional and Doppler echocardiography.

Obstruction to pulmonary venous return may be associated with a number of congenital cardiovascular abnormalities occurring both before and after surgery. Hemodynamic assessment by cardiac catheterization is often difficult. A noninvasive method for detection and quantitation of obstruction to systemic ventricular inflow would be clinically useful. Two-dimensionally directed pulsed and continuous wave Doppler echocardiography was performed before cardiac catheterization in 31 patients thought clinically to have possible obstruction to left ventricular inflow or pulmonary venous return. Primary diagnoses included transposition of the great arteries after the Mustard or Senning procedure in nine patients, total anomalous pulmonary venous connection in nine (in two after surgical repair), cor triatriatum in eight (in four after surgical repair), congenital mitral stenosis in four (in one after surgical repair) and mitral atresia in one. Severe obstruction was defined as a mean pressure gradient at catheterization of greater than or equal to 16 mm Hg at any level of the pulmonary venous return or of the systemic ventricular inflow. Severe obstruction was predicted if Doppler examination measured a flow velocity of greater than or equal to 2 m/s across any area of inflow obstruction. At catheterization, 12 patients (39%) had severe obstruction to left ventricular inflow or pulmonary venous return and all obstructions were correctly detected by Doppler echocardiography. The site of pulmonary venous obstruction was localized by two-dimensionally directed pulsed Doppler study. Patients with a lesser degree of obstruction had a lower Doppler velocity, but none had a maximal Doppler velocity of greater than or equal to 2 ms/s.(ABSTRACT TRUNCATED AT 250 WORDS)

Surgery without catheterization for congenital heart defects: management of 100 patients.

Little information is available regarding the surgical mortality of children with congenital heart disease who undergo operation on the basis of clinical assessment and echocardiographic diagnosis without cardiac catheterization. If catheterization affects early surgical mortality then perhaps omitting it would improve survival. Early operative mortality of 100 patients managed with echocardiography without preoperative catheterization (Group I) was compared with that of 151 diagnosis-matched control patients who had catheterization (Group II). The catheterization (Group II) and echocardiographic (Group I) groups included patients with the following diagnoses: atrial septal defect (33 and 17 in Group II and Group I, respectively); pulmonary stenosis/pulmonary atresia (33 and 15), aortic stenosis (14 and 3), coarctation of aorta (36 and 29), patent ductus arteriosus (10 and 15) and miscellaneous (25 and 21). Age range was 1 day to 16 years (mean 3.5); 114 (45%) of the 251 patients were less than 1 year of age and 59 (29%) were less than 1 month of age. With one exception, echocardiographic diagnosis was correct when compared with findings at surgery or autopsy, or both. Surgical mortality was 18% in Group I and 9% in Group II; however, multiple logistic regression analysis adjusting for differences in age and preoperative condition showed no significant difference between the two groups with a trend toward lower mortality in Group I (p = 0.075). Echocardiography as the definitive imaging modality in selected patients with congenital heart disease is accurate and is comparable with conventional methods of preoperative diagnosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Results of balloon valvuloplasty in typical and dysplastic pulmonary valve stenosis: Doppler echocardiographic follow-up.

To assess the usefulness of balloon valvuloplasty in patients with a dysplastic pulmonary valve, the files of 36 patients (aged 1 day to 18.5 years) who had two-dimensional echocardiography before and continuous wave Doppler echocardiography late after balloon valvuloplasty (balloon diameter greater than or equal to 20% anulus diameter) were reviewed. Results of relief of pulmonary stenosis were graded by catheter gradient in the catheterization laboratory and compared with Doppler echocardiographic findings at follow-up. There were 32 patients with typical pulmonary stenosis and 4 with a dysplastic valve. In the 32 patients with typical pulmonary stenosis, transvalvular gradient changed from a mean of 67 +/- 32 to 20 +/- 20 mm Hg (p less than 0.0001, mean reduction 72.6%). The gradients at follow-up by Doppler echocardiography averaged 20 mm Hg including 15 that increased, 3 that were unchanged and 14 that decreased. Only 3 (9%) of 32 patients had a gradient greater than 25 mm Hg at follow-up and only one gradient was greater than 35 mm Hg. All four patients with a dysplastic valve had a gradient that decreased with valvuloplasty from a mean of 85 +/- 33 to 33 +/- 20 mm Hg (p less than 0.05); gradient reduction in this group ranged from 40 to 85% (mean 57.5%). The gradient at follow-up increased in three of these four patients and decreased in one (the only late gradient less than 25 mm Hg). Late gradient was less than 35 mm Hg in two of the four patients and was reduced by 43 and 57%, respectively, in the other two.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnosis and management of fetal cardiac tumors: a multicenter experience and review of published reports.

OBJECTIVES: We sought to determine the prevalence and natural history of cardiac tumors in patients referred for fetal echocardiography. BACKGROUND: Cardiac tumors are rare; the prevalence, reported from autopsy studies of patients of all ages, varies from 0.0017% to 0.28%. Despite many case reports, the prevalence and natural history of fetal cardiac tumors are unclear. METHODS: Fourteen thousand fetal echocardiograms recorded over an 8-year period in seven centers were available for retrospective review. Medical records and echocardiograms were studied to determine the reason for referral, family history of tuberous sclerosis, prenatal and postnatal course and tumor description and type. RESULTS: Cardiac tumors were present in 19 pregnancies (0.14%). Gestational age at diagnosis ranged from 21 to 38 weeks. The most common indication for referral was a mass on an obstetric ultrasound study. The tumors were singular in 10 patients and multiple in 9. Tumor size ranged from 0.4 x 0.4 to 3.5 x 4 cm, and the majority of tumors were not hemodynamically significant. There were 17 patients with rhabdomyomas, 1 with a fibroma and 1 with an atrial hemangioma. Tuberous sclerosis complex was diagnosed in 10 patients. Partial or complete tumor regression was seen in eight patients; tumors were unchanged in five; and three required operation. CONCLUSIONS: Fetal cardiac tumors, a rare condition, are often benign. The majority of tumors are rhabdomyomas, but not all fetuses with rhabdomyoma have tuberous sclerosis.

Continuous-wave Doppler in children with ventricular septal defect: noninvasive estimation of interventricular pressure gradient.

Continuous-wave Doppler was used to estimate the pressure gradient between the right and left ventricles in 28 children with ventricular septal defect (VSD). Doppler measurement of maximal velocity was performed during cardiac catheterization and the Doppler-predicted gradient was compared with the peak-to-peak gradient measured simultaneously by catheter. Doppler gradients ranged from 10 to 71 mm Hg and correlated well with measured gradient (r = 0.97, p greater than or equal to 0.001). Fourteen patients had isolated VSD, and in these patients Doppler measurements of gradient allowed accurate estimation of right ventricular pressure (r = 0.93). There was an inverse correlation between the ratio of pulmonary to systemic resistance and maximal velocity (r = -0.77). Thus, continuous-wave Doppler is an accurate means of measuring instantaneous VSD pressure gradient in children with congenital heart disease and can be used to estimate the right ventricular and pulmonary artery pressure in children with isolated VSD. This noninvasive method can be used to distinguish restrictive from nonrestrictive VSD.