Aaron Bell

Detection of coronary artery anomalies in infants and young children with congenital heart disease by using MR imaging.

PURPOSEnTo evaluate the feasibility and accuracy of magnetic resonance (MR) coronary angiography for the detection of coronary artery anomalies in infants and children by using surgical findings as a reference.nnnMATERIALS AND METHODSnThe data analysis was approved by the institutional review board. One hundred children with congenital heart disease underwent MR coronary angiography while under general anesthesia (mean age ± standard deviation, 3.9 years ± 3; age range, 0.2-11 years). A navigator-gated, T2-prepared, three-dimensional steady-state free precession whole-heart protocol (isotropic voxel size, 1.0-1.3 mm(3); mean imaging time, 4.6 minutes ± 1.2; mean navigator efficiency, 70%; 3-mm gating window) was used after injection of gadopentetate dimeglumine. The cardiac rest period (end systole or middiastole) and acquisition window were prospectively assessed for each patient. Coronary artery image quality (score of 0 [nondiagnostic] to 4 [excellent]), vessel sharpness, and coronary artery anomalies were assessed by two observers. Surgery was performed in 58 patients, and those findings were used to define accuracy. Variables were assessed between age groups by using either analysis of variance or Kruskal-Wallis tests.nnnRESULTSnDiagnostic image quality (score, ≥1 for all coronary artery segments) was obtained in 46 of the 58 patients (79%) who underwent surgery. The origin and course of the coronary artery anatomy depicted with MR imaging was confirmed at surgery in all 46 patients-including the four (9%) with substantial coronary artery anomalies. Diagnostic-quality images were obtained in 84 of the 100 patients. The rate of success improved significantly when patients were older than 4 months (88% for patients >4 months vs 17% for patients ≤4 months, P < .001).nnnCONCLUSIONnImproved whole-heart MR coronary angiography enables accurate detection of abnormal origin and course of the coronary artery system even in very young patients with congenital heart disease.

Serial Magnetic Resonance Imaging in Hypoplastic Left Heart Syndrome Gives Valuable Insight Into Ventricular and Vascular Adaptation

Objectives This study sought to investigate changes in magnetic resonance imaging (MRI) ventricular volumes and vascular dimensions before hemi-Fontan (HF) and before total cavopulmonary connection (TCPC) in children with hypoplastic left heart syndrome (HLHS). Background The systemic right ventricle (RV) in HLHS is subject to significant changes in volume loading throughout the surgical stages of palliation, particularly after the HF. Methods Fifty-eight patients had paired pre-HF and pre-TCPC MRI for assessment of changes of RV volumes, neoaortic flow, and vascular dimensions. Results Comparison of pre-HF and pre-TCPC MRI results showed a decrease of indexed RV end-diastolic volume and end-systolic volume (98 ml/m2 to 87 ml/m2 and 50 ml/m2 to 36 ml/m2, respectively) with stroke volume remaining constant (49 ml/m2 vs. 51 ml/m2), leading to an increased RV ejection fraction (51% vs. 59%). These findings persisted after excluding the 3 patients who underwent tricuspid valve repair as part of their HF procedure. Indexed RV end-diastolic volume plotted against neoaortic stroke volume demonstrated a Frank-Starling–like curve that shifted upward after HF. The indexed distal left and right cross-sectional pulmonary artery areas were reduced after HF. Conclusions In HLHS, serial MRI shows the adaptation of the systemic RV after HF with volume reduction in the context of a preserved stroke volume and an increased ejection fraction. The staged palliation in HLHS may be a risk factor particularly for reduced left pulmonary artery growth in itself as no factors investigated in this study were found to significantly impact on this.

Subjective Evaluation of Right Ventricular Systolic Function in Hypoplastic Left Heart Syndrome: How Accurate Is It?

Background The geometry and heterogeneity of the right ventricle in hypoplastic left heart syndrome makes objective echocardiographic assessment of systolic function challenging. Consequently, subjective echocardiographic assessment of right ventricular (RV) function is still routinely undertaken. The aims of this study were to compare this with magnetic resonance imaging (MRI), investigate the impact of experience and training on the accuracy of subjective assessment, and critically analyze the role of echocardiography to detect impaired systolic function. Methods A retrospective analysis of prospectively acquired data was performed. Children with hypoplastic left heart syndrome underwent routine preoperative cardiac MRI and echocardiography under the same general anesthetic. Echocardiograms were reviewed, and members of the congenital heart disease team with differing echocardiography experience subjectively graded RV systolic function (good, moderate, or poor). This was compared with MRI-derived ejection fraction. Results Twenty-eight patients at different palliative stages were included. Twenty-eight observers were divided into five experience categories (congenital heart disease junior trainees to attending cardiologists). Median agreement was 47.6% (range, 31.4%–58.2%), with the lowest agreement among junior trainees and the highest among attending cardiologists. When used as a screening test for poor RV systolic function, the median sensitivity of echocardiography was 0.89 (range, 0.86–0.96), and median specificity was 0.45 (range, 0.26–0.55). The highest sensitivity was observed among junior trainees but with the lowest specificity. The highest specificity was observed among attending cardiologists (0.55). Conclusions Agreement between echocardiographic and MRI RV ejection fraction improves with experience but remains suboptimal. When used as a screening test for poor RV function, echocardiography is sensitive, but specificity is heavily influenced by operator experience.

Congenital Heart Disease: Cardiovascular MR Imaging by Using an Intravascular Blood Pool Contrast Agent

PURPOSEnTo compare the image quality and diagnostic performance of a contrast agent-specific inversion-recovery (IR) steady-state free precession (SSFP) magnetic resonance (MR) imaging sequence performed by using an intravascular contrast agent (gadofosveset trisodium) with those of a commonly used T2-prepared SSFP sequence performed by using an extravascular (gadopentetate dimeglumine) and an intravascular (gadofosveset trisodium) contrast agent in patients with congenital heart disease (CHD).nnnMATERIALS AND METHODSnThe local ethics committee and the United Kingdom Medicines and Healthcare products Regulatory Agency approved this study. Patient informed consent was obtained. Twenty-three patients with CHD were examined by using a 1.5-T MR imaging unit and a 32-channel coil. Gadopentetate dimeglumine and gadofosveset trisodium were used in the same patient on consecutive days. Vessel wall sharpness, contrast-to-noise ratios (CNRs), image quality, and diagnostic performance achieved by using the IR SSFP sequence with gadofosveset trisodium were compared with those achieved by using the T2-prepared SSFP sequence with gadopentetate dimeglumine and gadofosveset trisodium and with those achieved at respective contrast material-enhanced MR angiographic examinations. The Wilcoxon rank sum test was used to compare categoric variables; t tests were used to compare continuous variables.nnnRESULTSnUse of the IR SSFP sequence with gadofosveset trisodium significantly improved vessel wall sharpness, CNRs, and image quality (P < .05 for all) for all investigated intra- and extracardiac structures compared with the T2-prepared SSFP sequence with gadopentetate dimeglumine and gadofosveset trisodium and the respective contrast-enhanced MR angiographic examinations. With use of the IR SSFP sequence with gadofosveset trisodium, new, unsuspected diseases (five [22%] of 23) were diagnosed, while other diseases could be excluded (15 [65%] of 23). Information available from echocardiography (n = 23), conventional angiography (n = 4), and/or surgery (n = 1) confirmed all diagnoses.nnnCONCLUSIONnIR SSFP with gadofosveset trisodium improved image quality and diagnostic performance, allowing a more accurate and complete assessment of cardiovascular anatomy in patients with CHD compared with T2-prepared SSFP with gadopentetate dimeglumine and gadofosveset trisodium and respective contrast-enhanced MR angiographic examinations.

Cardiovascular MR imaging of conotruncal anomalies.

Conotruncal anomalies are congenital heart defects that result from abnormal formation and septation of the outflow tracts of the heart and great vessels. The major conotruncal anomalies include tetralogy of Fallot, transposition of the great arteries, double-outlet right ventricle, truncus arteriosus, and interrupted aortic arch. Cardiovascular magnetic resonance (MR) imaging is an important modality for the evaluation of patients with these defects. Major advances in cardiovascular MR imaging equipment and techniques allow precise delineation of the cardiovascular anatomy and accurate quantitative assessment of ventricular function and blood flow. The data provided by cardiovascular MR imaging are useful for treatment planning and posttreatment monitoring, supplement information obtained with echocardiography, and in many cases obviate cardiac catheterization.

Optimal imaging after coarctation stenting

The management of coarctation of the aorta (COA) has evolved considerably since the initial surgical repair was described in 1945.1 Surgery is now invariably by an end-to-end anastomosis after excision of the coarctation segment and in neonates and infants is often extended to address coexistent aortic arch hypoplasia.2 While surgery was evolving, catheter intervention also developed and beyond the first 6–12u2005months of age became routine treatment in many (though not all) centres.3 Catheter intervention, in addition to being used for primary treatment, is also used to correct residual defects (both stenotic and aneurysmal) from earlier surgery or catheter procedures.4 5 Many patients considered to be “repaired” according to criteria established in the early surgical era are now found to have residual defects with modern tomographic imaging or have residual hypertension that requires treatment.6 7nnCatheter intervention with balloon dilatation for re-coarctation in the 1980s evolved to balloon dilatation for native coarctation in a limited number of centres, but with the advent of endovascular stenting in the 1990s and covered stent implantation in the 2000s is increasingly becoming the approach of choice.8 9 As with many other developments in congenital heart disease, this changing approach was never compared to surgery (which was also constantly evolving) in randomised trials. Thus the true value of coarctation stenting can only be judged by publication of large series with extended clinical follow-up.nnChakrabarti et al present a large single centre study of coarctation stenting in 88 patients over a 6-year period in this issue of Heart ( see page 1212 ).10 As with many smaller series, the results are excellent. Gradients across the coarctation segment were reduced and blood pressure control improved with a low rate of acute complications (one patient required emergency surgery for aortic rupture). While follow-up …

Image orientation for three-dimensional echocardiography of congenital heart disease

To date there has been little discussion about image orientation for three-dimensional (3D) echocardiography when applied to congenital heart lesions. Anatomic relations cannot be assumed in congenital heart disease and image cropping during post processing may by necessity remove external or even internal anatomic references. We present an approach to consistent anatomic orientation which is both intuitive and consistent with regard to superior–inferior, anterior–posterior and left–right axes. Such anatomic orientation is also concordant with other common 3D imaging modes such as cardiac magnetic resonance imaging and computed tomography. Views derived from standard cross sectional echocardiography have such universal familiarity that analogous 3D projections of these views may be retained but novel hitherto unavailable views such as en face views of the cardiac septums or atrioventricular valves may be projected using anatomic orientation.

Noninvasive assessment of pulmonary artery flow and resistance by cardiac magnetic resonance in congenital heart diseases with unrestricted left-to-right shunt

OBJECTIVESnTo determine whether noninvasive assessment of pulmonary artery flow (Qp) by cardiac magnetic resonance (CMR) would predict pulmonary vascular resistance (PVR) in patients with congenital heart disease characterized by an unrestricted left-to-right shunt.nnnBACKGROUNDnPatients with an unrestricted left-to-right shunt who are at risk of obstructive pulmonary vascular disease require PVR evaluation preoperatively. CMR cardiac catheter (XMR) combines noninvasive measurement of Qp by phase contrast imaging with invasive pressure measurement to accurately determine the PVR.nnnMETHODSnPatients referred for clinical assessment of the PVR were included. The XMR was used to determine the PVR. The noninvasive parameters, Qp and left-to-right shunt (Qp/Qs), were compared with the PVR using univariate regression models.nnnRESULTSnThe XMR was undertaken in 26 patients (median age 0.87 years)-ventricular septal defect 46.2%, atrioventricular septal defect 42.3%. Mean aortic flow was 2.24 +/- 0.59 l/min/m(2), and mean Qp was 6.25 +/- 2.78 l/min/m(2). Mean Qp/Qs was 2.77 +/- 1.02. Mean pulmonary artery pressure was 34.8 +/- 10.9 mm Hg. Mean/median PVR was 5.5/3.0 Woods Units (WU)/m(2) (range 1.7 to 31.4 WU/m(2)). The PVR was related to both Qp and Qp/Qs in an inverse exponential fashion by the univariate regression equations PVR = exp(2.53 - 0.20[Qp]) and PVR = exp(2.75 - 0.52[Qp/Qs]). Receiver-operator characteristic (ROC) analysis was used to determine cutoff values for Qp and Qp/Qs above which the PVR could be regarded as clinically acceptable. A Qp of > or =6.05 l/min/m(2) predicted a PVR of < or =3.5 WU/m(2) with sensitivity 72%, specificity 100%, and area under the ROC curve 0.90 (p = 0.002). A Qp/Qs of > or =2.5/1 predicted a PVR of < or =3.5 WU/m(2) with sensitivity 83%, specificity 100%, and area under the curve ROC 0.94 (p < 0.001).nnnCONCLUSIONSnMeasurement of Qp or left-to-right shunt noninvasively by CMR has potential to predict the PVR in patients with an unrestricted left-to-right shunt and could potentially determine operability without having to undertake invasive testing.

Atypical atrial septal defects in children: noninvasive evaluation by cardiac MRI

BackgroundAtypical left-to-right shunts at the level of the atrium in children such as sinus venosus atrial septal defects (ASDs) and partial anomalous pulmonary venous return (PAPVR) may be difficult to assess by transthoracic or transoesophageal echocardiography. Free-breathing cardiac MRI may be a powerful alternative.ObjectiveTo assess the value of free-breathing cardiac MRI in the delineation of atypical ASDs in children.Materials and methodsA total of 82 children (mean age 5.9xa0years, range 1.1–15.7xa0years) with suspected ASD and inconclusive transthoracic echocardiography underwent cardiac MRI under free-breathing, mostly sedated conditions. Phase-contrast MRI was used for defect visualization and shunt quantification, and multiphase inflow MR angiography for delineation of pulmonary/systemic venous connections.ResultsOf the 82 patients, 34 (41%) were diagnosed with atypical shunt lesions at the level of the atrium and 48 (59%) with simple secundum ASDs. No false-negative or false-positive findings were reported by MRI compared to cardiac catheterization and intraoperative findings. Superior sinus venosus ASD with partial anomalous PAPVR was present in 10 of the 82 children (12.2%), whereas 2 (2.4%) had a large posterior-inferior defect, 5 (6.1%) had isolated PAPVR, and 17 (20.7%) had multiple ASDs and/or associated vascular anomalies. Qp/Qs by phase-contrast MRI agreed well with oximetry values (mean difference 3%, limits of agreement ±21–25%; Bland/Altman analysis).ConclusionFree-breathing cardiac MRI under sedation allows reliable identification of atypical left-to-right shunt defects at the level of the atrium in children in whom transcatheter ASD closure is unsuitable, including delineation of pulmonary or systemic venous anomalies and shunt quantification.

Assessment of right ventricular volumes in hypoplastic left heart syndrome by real-time three-dimensional echocardiography: comparison with cardiac magnetic resonance imaging

BACKGROUNDnAccurate assessment of right ventricular (RV) volumes and function is important in patients with hypoplastic left heart syndrome (HLHS). We prospectively sought to determine the reproducibility of three-dimensional (3D) echocardiography and its agreement with cardiac magnetic resonance imaging (CMR) in HLHS.nnnMETHODS AND RESULTSnTwenty-eight patients underwent CMR followed immediately by transthoracic 3D echocardiography under general anaesthesia. Semi-automated border detection software was used to determine echocardiographic RV volumes. Inter- and intra-observer variability, correlation and levels of agreement between techniques were determined. The median age was 0.37 years (0.18-9.28 years) and weight 6.24 kg (3.42-32.50 kg). Intra- and inter-observer variability was excellent for both techniques. Median (range) measurements for 3D echocardiography and CMR were; end-diastolic volume (EDV) 23.6 mL (6.5-63.2) and 30.6 mL (11.8-87.9), end-systolic volume (ESV) 12.6 mL (3.7-37.0) and 14.9 mL (5.8-33.9), stroke volume (SV) 11.2 mL (2.8-33.0) and 17.1 mL (6.0-54.1), ejection fraction (EF) 48.2% (31.2-64.9), and 56.5% (42.7-72.2). Correlation coefficients were r = 0.85, 0.84, 0.83, and 0.74, respectively (P < 0.01 for all). Volumetric data were expressed as a percentage of the echocardiographic volume to CMR volume. When compared with CMR, 3D echocardiography underestimated EDV, ESV and SV by 26.7% (SD ± 20.2), 10.6% (±28.1), and 37.5% (±20.1), respectively. The difference in volume appeared largest at low ventricular volumes. EF was 8.3% (±7.3) lower by 3D echocardiography compared with CMR.nnnCONCLUSIONnBoth 3D echocardiography and CMR volumes appear highly reproducible. Measurements obtained by 3D echocardiography are significantly lower than those obtained by CMR, with wide limits of agreement such that these two methods cannot be used interchangeably.