Three-dimensional echocardiography for the assessment of atrioventricular valves in congenital heart disease: past, present and future.

Echocardiography has developed as an imaging technology over 60 years to become the mainstay for investigating heart disease, providing invaluable structural and functional information. In the last 20 years, 3-dimensional echocardiography (3DE) has emerged as an adjunct to 2-dimensional echocardiography in adult and congenital heart disease. Early work with 3-dimensional imaging of the mitral valve describing normal annular shape and function significantly changed the understanding of mitral valve dynamics. Further work led to our current understanding of the mitral valve working as a unit, with all components vital to its normal function. With improving technology and ease of use, similar 3DE techniques have been used in congenital heart disease to study the unique anatomy and function of atrioventricular (AV) valves, specifically the tricuspid valve in hypoplastic left heart syndrome, and the left AV valve in atrioventricular septal defects. This paper describes the role of 3DE in assessing AV valve function in normal valves, and in congenital heart disease.

Three-dimensional echocardiography in the assessment of congenital mitral valve disease.

Congenital mitral valve abnormalities are rare and cause mitral stenosis, regurgitation, or a combination of the two. Three-dimensional echocardiography has provided new insight into the structure and function of both normal and abnormal mitral valves. Three-dimensional imaging permits accurate anatomic diagnosis and enhances two-dimensional echocardiographic data. Moreover, it enables echocardiographers to communicate effectively with cardiothoracic surgeons when displaying, analyzing, and describing pathology. The purpose of this report is to review congenital mitral valve disease, focusing on the benefits of three-dimensional echocardiography in its evaluation.

Effectiveness of prenatal screening for congenital heart disease: assessment in a jurisdiction with universal access to health care.

BACKGROUND: Neonates with certain forms of severe congenital heart disease (CHD) diagnosed prenatally might have better outcomes in comparison with those diagnosed after birth. The proportion of prenatally detected neonates with severe CHD and the effect of prenatal diagnosis on clinical outcomes have not been previously investigated in Canada. METHODS: We retrospectively studied infants in Alberta, Canada, who required surgical or catheter intervention for CHD at younger than 1 year of age, between January 2007 and December 2010, and pregnancy terminations affected by CHD. RESULTS: Of the 374 subjects identified (327 infants, 47 pregnancies with termination), 188 (50%) were detected prenatally. Failure of prenatal diagnosis was associated with anomalies not involving the 4-chamber view on ultrasound (odds ratio, 1.86; 95% confidence interval, 1.48-2.35; P < 0.001) and region of residence (P = 0.04). Prenatal detection was associated with fewer days to hospital admission (P < 0.001), fewer days to surgery (P = 0.003), and greater use of prostaglandins (P = 0.001). Infants diagnosed prenatally who underwent surgery within 15 days of age had higher preductal O2 saturations (P = 0.04), fewer days to admission (P = 0.03), and less frequently required preoperative intubation (P = 0.004), and inotropes (P = 0.001). Pregnancy termination occurred among 49% of fetuses detected before 24 weeks' gestation. CONCLUSIONS: Only 50% of fetuses and/or neonates with severe CHD managed in Alberta have a prenatal diagnosis. The likelihood of prenatal detection is influenced by the status of the 4-chamber view on ultrasound and the region of maternal residence indicating heterogeneous access to fetal echocardiography within Alberta. Prenatal detection might improve clinical outcomes for neonates with severe CHD.

The assessment of atrial function in single ventricle hearts from birth to Fontan: a speckle-tracking study by using strain and strain rate.

BACKGROUND: Single ventricle (SV) exercise performance is impaired and limited by reduced ventricular preload reserve. The atrium modulates ventricular filling, and enhancement of atrial compliance can increase cardiac performance. We aimed to study atrial mechanics in SV hearts across staged surgical palliation compared with healthy children by using novel speckle-tracking echocardiography techniques. METHODS: A cross-sectional study of 81 patients with SV (1 day to 6.5 years) at 4 stages of surgical palliation (presurgery, 22; prebidirectional cavopulmonary anastomosis, 23; pre-Fontan, 22; post-Fontan, 14). The dominant atrium was assessed with speckle-tracking echocardiography for active (εact), conduit (εcon), and reservoir (εres) strain; strain rate (SR); and εact/εres ratio before each stage of surgical palliation. Findings were compared with the left atrium of 51 healthy children (1 day to 5.5 years). RESULTS: Single ventricle atrial size was increased (P < .01), and atrial εres was decreased (P < .01) compared with healthy controls. SV atrial εcon (P < .01) and SRcon (P < .0001) was decreased, increased εact persisted (P < .05), and εact/εres was increased (P < .001) between surgical stages. Although the expected maturational trend of increasing εcon, decreasing εact, and εact/εres occurred in SV, they lagged behind healthy maturational changes (P < .0001). CONCLUSION: Single ventricle atrium is dilated, has deceased compliance, decreased early diastolic emptying, and increased reliance on active atrial contraction for ventricular filling. This deviates from normal early childhood maturational changes and appears to parallel those of an atrium facing early ventricular diastolic dysfunction.

Serial assessment of right ventricular volume and function in surgically palliated hypoplastic left heart syndrome using real-time transthoracic three-dimensional echocardiography.

BACKGROUND: Right ventricular (RV) failure is a major cause of morbidity and mortality in patients with hypoplastic left heart syndrome (HLHS), but the longitudinal course of RV volumes through staged palliation (SP) has not been previously investigated. The aim of this study was to evaluate RV volume and function longitudinally through SP of HLHS using real-time three-dimensional echocardiography. METHODS: A total of 18 subjects with HLHS were prospectively studied at four time points from diagnosis through stage 2 (SP2). Real-time three-dimensional echocardiographic full-volume data sets were acquired in high-frame rate mode with electrocardiographic gating. Volumetric and functional analyses were performed using a semiautomatic contour detection algorithm. Eighteen age-matched and sex-matched normal infants (aged 0-6 months) were studied at comparable time points as controls. RESULTS: Presurgical examinations (pre-stage 1 [SP1]; n = 18) were performed at a mean age of 4 days, post-SP1 examinations (n = 17) at a mean age of 20 days, pre-SP2 examinations (n = 14) at a mean age of 4.6 months, and post-SP2 examinations (n = 14) at a mean age of 5.5 months, constituting a total of 63 examinations. The mean values of RV end-diastolic volume indexed to body surface area (EDVi) at the four time points were 87 ± 30, 104 ± 39, 112 ± 34, and 102 ± 35 mL/m(2), respectively. There was an increase in EDVi (P = .024) from pre-SP1 to post-SP1 but no significant change between post-SP1 and pre-SP2. The decrease in EDVi after SP2 did not reach statistical significance. Mean RV ejection fractions (EFs) were 50 ± 5%, 45 ± 5%, 46 ± 5%, and 38 ± 4%, respectively. There was a trend toward decreasing EF throughout SP, with statistically significant decreases from pre-SP1 to post-SP1 (P = .003) and from pre-SP2 to post-SP2 (P < .001). In normal infants, the mean RV EDVi was 50 ± 10 mL/m(2) (approximately half that of patients with HLHS), and the mean EF was 51 ± 3%. There was good interobserver agreement for EDVi, end-systolic volume indexed to body surface area, and EF. CONCLUSIONS: Real-time three-dimensional echocardiography is a reproducible means for evaluating RV volumes and EFs in patients with HLHS. Indexed RV diastolic volume remains stable to slightly increased, and RV EF deteriorates as the first two stages of surgical palliation are accomplished. The findings of this study highlight the adverse physiology of HLHS, which deteriorates even among early survivors despite SP.

Incremental diagnostic yield of pediatric cardiac assessment after fetal echocardiography in the offspring of women with congenital heart disease: a prospective study.

OBJECTIVE: We sought to determine the incremental diagnostic utility of pediatric cardiac assessment in the offspring of women with congenital heart disease who have had previous fetal echocardiography. PATIENTS AND METHODS: We prospectively followed pregnant women with congenital heart disease who were receiving care at 2 obstetric and cardiac centers and identified 276 infants who underwent both fetal echocardiography and pediatric cardiac assessment. All of the infants with abnormal fetal echocardiography findings or abnormal pediatric cardiac assessments underwent subsequent confirmatory pediatric echocardiography. RESULTS: In this cohort, congenital heart disease was detected in 22 (8%) of 276 offspring born to women with congenital heart disease. There was concordance between the results of fetal echocardiography and pediatric cardiac assessment in 235 (85%) of 276 offspring (231, both normal; 4, both abnormal) and discordance between the results of fetal echocardiography and pediatric cardiac assessment in 41 (15%) of 276 infants. In the 41 subjects with discordant results, there were normal fetal echocardiography findings but abnormal pediatric cardiac assessments in 35 of 41 (pediatric echocardiography revealed congenital heart disease in 18 of 35 and normal anatomy in 17 of 35) and abnormal fetal echocardiography findings but normal pediatric cardiac assessments in 6 of 41 (pediatric echocardiography findings normal in all 6 of the infants). Fetal echocardiography detected all of the major forms of congenital heart disease. Lesions missed by fetal echocardiography but detected on pediatric cardiac assessment included shunt lesions and minor valvular abnormalities. CONCLUSIONS: Although fetal echocardiography can reliably exclude major forms of congenital heart disease, minor congenital heart disease lesions can be missed on fetal echocardiography; however, these can be diagnosed with careful pediatric cardiac assessment. Postnatal pediatric cardiac assessment has incremental diagnostic utility for the detection of congenital heart disease in the offspring of women with congenital heart disease and previous fetal echocardiography.

Disruption of the ventricular myocardial force-frequency relationship after cardiac surgery in children: noninvasive assessment by means of tissue Doppler imaging.

OBJECTIVE: Impaired ventricular function after cardiopulmonary bypass and surgical repair remains a commonly encountered clinical problem. We hypothesized that the well-described impairment of calcium cycling after cardiac surgery would significantly affect the ventricular myocardial force-frequency relationship, which can be measured noninvasively by using the tissue Doppler echocardiography-derived index of contractility isovolumic acceleration. METHODS: Children undergoing repair of congenital heart defects were studied. Rate-related changes in contractility were measured by means of simultaneous atrial pacing and tissue Doppler echocardiography preoperatively and postoperatively. RESULTS: Although closure of atrial septal defect did not affect ventricular myocardial systolic performance, closure of ventricular septal defect lead to a marked postoperative decrease of basal contractile force (2.0 +/- 0.7 m/s2 preoperatively vs 1.0 +/- 0.7 m/s2 postoperatively, P < .02). Furthermore, the force-frequency relationship curves were significantly different (P < .001), with a reduced force-rate trajectory, and also peak force was attained. Neonates undergoing the arterial switch procedure showed the most marked postoperative decrease of isovolumic acceleration at basal heart rates and force-frequency relationship with reduced trajectory and peak force development (P < .0001). CONCLUSIONS: This is the first clinical study describing the noninvasive acquisition of ventricular force-frequency relationships in children undergoing operations for congenital heart disease. There is a marked variability in response, ranging from no effect in patients undergoing atrial septal defect closure to a profound reduction in myocardial contractile responses after neonatal arterial switch. This simple noninvasive method allows measurement of a hitherto rarely examined property of the myocardium, an understanding of which might allow refinement of myocardial protection and postoperative myocardial support.

Phase-contrast MR assessment of pulmonary venous blood flow in children with surgically repaired pulmonary veins.

BACKGROUND: Pulmonary venous (PV) obstruction may complicate surgical repair of PV abnormalities. By combining phase-contrast cine (PC) imaging and contrast-enhanced angiography, magnetic resonance (MR) imaging can provide physiological information complementing anatomical diagnosis. OBJECTIVES. To compare the PV flow pattern observed after surgical repair of PV abnormalities with normal PV flow pattern and to investigate the changes occurring in the presence of PV stenosis by using PC MR in children. MATERIALS AND METHODS: By using PC MR, PV flow was evaluated in 14 patients (3 months-14 years) who underwent surgical repair for PV abnormalities. Eleven children (8-18 years) were studied as normal controls. Peak flow velocities and patterns were compared among three groups: normal veins ( n=23), surgically repaired veins without ( n=44) and with stenosis ( n=10). RESULTS: Normal and unobstructed pulmonary veins after surgery showed a biphasic or triphasic flow pattern with one or two systolic peaks and a diastolic peak. Unobstructed surgically repaired veins showed decreased peak systolic velocity ( P =0.001) and an increased peak diastolic velocity ( P=0.005) when compared to normal values. Obstructed veins showed decreased systolic and diastolic velocities when measured upstream from the stenosis. CONCLUSION: PC MR shows different flow patterns among normal, surgically repaired pulmonary veins with and without stenosis.

Assessment of the thymus at echocardiography in fetuses at risk for 22q11.2 deletion.

OBJECTIVES: An absent or hypoplastic thymus is common in patients with 22q11.2 deletion (del22q11.2). We sought to determine whether fetal echocardiography could identify absence of the thymus as a diagnostic tool in pregnancies at risk for fetal del22q11.2. METHODS: We evaluated the fetal thymus in 16 consecutive pregnancies at risk for fetal del22q11. Fourteen of the fetuses had a conotruncal cardiac lesion, one had a twin with a conotruncal lesion, and in one the mother had a diagnosis of del22q11.2. The fetal thymus assessment was performed by an individual who was not aware of the del22q11.2 status of the fetus. RESULTS: By 2D imaging, the thymus was identified in the anterosuperior mediastinum as a subtle hypoechogenic area. In nine cases, the thymus was demonstrated prenatally and none had del22q11.2. However, in one case the thymus was only seen on follow-up fetal echocardiography. In six cases, the thymus could not be identified and all six had del22q11.2. In one additional case, analyzed retrospectively, the thymus could not be assessed. The status of the thymus was confirmed on postnatal echocardiography or autopsy in 11 of the 15 cases assessed prenatally. CONCLUSIONS: Our study suggests that fetal echocardiography can assess the thymus in most cases at risk for del22q11.2. This information may be useful in counseling women/couples who decline amniocentesis or who are awaiting amniocentesis results.

In Vitro Feasibility and Accuracy of Three-Dimensional Echocardiography for Ventricular Volume Assessment in Very Small Hearts.

To evaluate the in vitro accuracy of three-dimensional echocardiography (3-DE) for estimation of ventricular volume in very small hearts, left ventricular (LV) volume was determined by 3-DE in the excised hearts of 10 guinea pigs and 10 rabbits, and right ventricular (RV) volume was determined in 20 rabbits. The effect of edge enhancement, Sigma filter, and slice distance (1 mm versus 0.5 mm) was assessed in each heart. True volumes were obtained from ventricular casts. Mean cast volume was 1.38 +/- 0.83 mL for LVs and 1.63 +/- 1.01 mL for RVs. Correlations between 3-DE and true volumes were r > 0.99 (P < 0.0001) for both ventricles. Accuracy was not affected by ventricular type, slice distance, or Sigma filter. Mean percent difference from true volume was significantly less (P = 0.03) with edge enhancement. Ventricular volume can be assessed reliably by 3-DE in very small hearts. The edge enhancement feature improved the accuracy of the measurements.