Noninvasive diagnostics in congenital heart disease: echocardiography and magnetic resonance imaging

Which cardiovascular magnetic resonance planes and sequences provide accurate measurements of branch pulmonary artery size in children with right ventricular outflow tract obstruction?

Children with right ventricular outflow tract obstructive (RVOTO) lesions require precise quantification of pulmonary artery (PA) size for proper management of branch PA stenosis. We aimed to determine which cardiovascular magnetic resonance (CMR) sequences and planes correlated best with cardiac catheterization and surgical measurements of branch PA size. Fifty-five children with RVOTO lesions and biventricular circulation underwent CMR prior to; either cardiac catheterization (n = 30) or surgery (n = 25) within a 6 month time frame. CMR sequences included axial black blood, axial, coronal oblique and sagittal oblique cine balanced steady-state free precession (bSSFP), and contrast-enhanced magnetic resonance angiography (MRA) with multiplanar reformatting in axial, coronal oblique, sagittal oblique, and cross-sectional planes. Maximal branch PA and stenosis (if present) diameter were measured. Comparisons of PA size on CMR were made to reference methods: (1) catheterization measurements performed in the anteroposterior plane at maximal expansion, and (2) surgical measurement obtained from a maximal diameter sound which could pass through the lumen. The mean differences (Δ) and intra class correlation (ICC) were used to determine agreement between different modalities. CMR branch PA measurements were compared to the corresponding cardiac catheterization measurements in 30 children (7.6 ± 5.6 years). Reformatted MRA showed better agreement for branch PA measurement (ICC > 0.8) than black blood (ICC 0.4-0.6) and cine sequences (ICC 0.6-0.8). Coronal oblique MRA and maximal cross sectional MRA provided the best correlation of right PA (RPA) size with ICC of 0.9 (Δ -0.1 ± 2.1 mm and Δ 0.5 ± 2.1 mm). Maximal cross sectional MRA and sagittal oblique MRA provided the best correlate of left PA (LPA) size (Δ 0.1 ± 2.4 and Δ -0.7 ± 2.4 mm). For stenoses, the best correlations were from coronal oblique MRA of right pulmonary artery (RPA) (Δ -0.2 ± 0.8 mm, ICC 0.9) and sagittal oblique MRA of left pulmonary artery (LPA) (Δ 0.2 ± 1.1 mm, ICC 0.9). CMR PA measurements were compared to surgical measurements in 25 children (5.4 ± 4.8 years). All MRI sequences demonstrated good agreement (ICC > 0.8) with the best (ICC 0.9) from axial cine bSSFP for both RPA and LPA. Maximal cross sectional and angulated oblique reformatted MRA provide the best correlation to catheterization for measurement of branch PA's and stenosis diameter. This is likely due to similar angiographic methods based on reformatting techniques that transect the central axis of the arteries. Axial cine bSSFP CMR was the best surgically measured correlate of PA branch size due to this being a measure of stretched diameter. Knowledge of these differences provides more precise PA measurements and may aid catheter or surgical interventions for RVOTO lesions.

Echocardiography and management of sick neonates in the intensive care unit

To evaluate the influence of echocardiographic examination in the clinical management of the sick neonate, 241 patients, admitted to the neonatal intensive care unit of a tertiary referral center that had echocardiograms with data available for review, were enrolled in a retrospective study. Asymptomatic murmurs (45%) followed by extracardiac anomalies/dysmorphic features (24%) were the most common clinical indications for requesting an echocardiogram. Congenital structural abnormalities (33%), hemodynamically significant patent arterial duct (3%), persistent pulmonary hypertension of the newborn (6%), and left ventricular dysfunction (3%) were the echocardiographic findings that subgrouped as structural or functional abnormalities. Patent oval foramen and hemodynamically nonsignificant patent arterial duct (20%) and physiologic pulmonary artery stenosis (1%) were categorized as normal structural group. Thirty-four percent of neonates had normal heart anatomy. This investigation changed the clinical management in at least 66% of newborns scanned, including emergency surgical intervention for 7%, medical treatment for 22%, and routine cardiologic follow-up for 37% of patients. Asymptomatic murmur in our critically ill neonates has been associated with a higher incidence of cardiac disease. Hence, echocardiography is an important tool for diagnosis of cardiac abnormalities that can influence the management and outcome of the sick newborn in the intensive care unit. A preliminary echocardiogram performed by the neonatologist under the supervision of a pediatric cardiologist for interpretation and review is an alternate when there is not a cardiologist "in house."

The Economic Evaluation of a Health Screening Program on Congenital Heart Disease for School Children in Taichung, Taiwan

Objective The objective of this study was the economic evaluation of screening school children for congenital heart disease (CHD). Methods The sample consisted of all the 45 725 students in grades 1 and 7 from Taichung County, Taiwan. STATISTICA, version 7.1, was used to determine descriptive statistics and Student's t tests on students' height, weight, and body mass index (BMI). Results The total cost of CHD screening was NT$4 863 866 (NT$32 = US$1), and the average cost was NT$106.37 per child. The rate of finding new asymptomatic students was 2.9174%, and the cost of finding 1 asymptomatic student was NT$3646. Also, a cost-effective analysis showed NT$165.7 per year of life saved. Conclusions Twelve Student's t tests were conducted, and it found that students' height, weight, and BMI was not associated with asymptomatic students. A goodness-of-fit χ2 found that females have a higher rate of asymptomatic CHD.

Live 3D Echocardiography: A Replacement for Traditional 2D Echocardiography?

OBJECTIVE

We describe the development of real-time 3D imaging and review the previously used versions of 3D echocardiography so that the reader will appreciate why current developments truly do represent a quantum leap in the technology.

CONCLUSION

Three-dimensional echocardiography has now been shown to have several advantages over 2D echocardiography, particularly for volume measurements, visualization of septal defects, and whole-valve evaluation. Given these data, it is clear that 3D echocardiography is here to stay and soon will become part of routine echocardiographic examinations.

Anaesthesia considerations for cardiac MRI in infants and small children

BACKGROUND

General anaesthesia is frequently necessary in infants and small children undergoing cardiac magnetic resonance imaging (MRI), because of the imaging techniques, MRI environment and potential need for breath-holding to facilitate imaging. Anaesthetizing paediatric patients with congenital heart disease (CHD) for cardiac MRI poses many challenges for the anaesthetist and this report reviews our experience.

METHODS

We retrospectively reviewed the anaesthesia and MRI records of all patients who had undergone cardiac MRI between January 2000 and October 2002.

RESULTS

A total of 250 children with cardiac disease underwent general anaesthesia for cardiac MRI. ASA classification included class I, 2%; class II; 26%; class III, 60% and class IV, 12%. A total of 168 patients (67%) had undergone previous cardiac surgery, 182 patients (94%) were discharged the same day and 48 patients (19.2%) had cyanotic cardiac defects (SpO2 between 55 and 85%). No scans were interrupted because of low oxygen saturation during breath-hold or haemodynamic instability. No patient was admitted to the hospital from complications related to general anaesthesia, but one inhouse patient from the cardiology ward was admitted to the cardiac intensive care unit (CICU) after the MRI because of cyanosis and low cardiac output. Seven patients from the CICU were on inotropic infusions when they underwent the MRI procedure and two others needed inotropic support after induction of anaesthesia. Five patients had a brief episode of hypotension during the MRI and responded quickly to interventions.

CONCLUSION

Our experience demonstrates that general anaesthesia for cardiac MRI can be provided safely in infants and small children with CHD, despite the complexity and pathophysiology of many defects, the frequent breath-holding for image acquisitions and the MRI environment.