Magnetic Resonance Imaging in Pediatric Pulmonary Hypertension

The present study aims to determine the efficacy and reliability of cardiovascular magnetic resonance imaging in establishing the diagnosis and prognosis of pulmonary hypertension in children.This is a retrospective comparison of 25 children with pulmonary hypertension and a control group comprising 19 healthy children. The diagnosis of pulmonary hypertension was made when the mean pulmonary artery pressure was ≥25 mmHg by catheter angiography.The children with pulmonary hypertension had significantly lower body mass indices than did the healthy children (P=0.048). In addition, the children with pulmonary hypertension had significantly larger main pulmonary artery diameters and ascending aortic diameters (both P=0.001) but statistically similar ratios of main pulmonary artery diameter-to-ascending aortic diameter. If the main pulmonary artery diameter was ≥25 mm, pediatric pulmonary hypertension was diagnosed with 72% sensitivity and 84% specificity. In the event that the ratio of main pulmonary artery diameter-to-ascending aorta diameter was ≥1, pediatric pulmonary hypertension was diagnosed with 60% sensitivity and 53% specificity. When compared with children who had New York Heart Association functional class II pulmonary hypertension, the children with functional class III pulmonary hypertension had significantly larger main (P=0.046), right (P=0.036), and left (P=0.003) pulmonary arteries.Cardiovascular magnetic resonance imaging is useful in the diagnosis of children with pulmonary hypertension. Pediatric pulmonary hypertension can be diagnosed with high sensitivity and specificity when the main pulmonary artery diameter measures ≥25 mm.     

Pulmonary Arterial Hypertension: Use of Delayed Contrast-Enhanced Cardiovascular Magnetic Resonance in Risk Assessment

Background

Pulmonary arterial hypertension is a severe and progressive disease. Its early diagnosis is the greatest clinical challenge.

Objective

To evaluate the presence and extension of the delayed myocardial contrast-enhanced cardiovascular magnetic resonance, as well as to verify if the percentage of the myocardial fibrosis mass is a severity predictor.

Methods

Cross-sectional study with 30 patients with pulmonary arterial hypertension of groups I and IV, subjected to clinical, functional and hemodynamic evaluation, and to cardiac magnetic resonance.

Results

The mean age of patients was 52 years old, with female predominance (77%). Among the patients, 53% had right ventricular failure at diagnosis, and 90% were in functional class II/III. The mean of the 6-minute walk test was 395m. In hemodynamic study with right catheterism, the mean average pulmonary arterial pressure was 53.3mmHg, of the cardiac index of 2.1L/ min.m², and median right atrial pressure was 13.5 mmHg. Delayed myocardial contrast enhanced cardiovascular magnetic resonance was found in 28 patients. The mean fibrosis mass was 9.9 g and the median percentage of fibrosis mass was 6.17%. The presence of functional class IV, right ventricular failure at diagnosis, 6-minute walk test < 300 meters and right atrial pressure ≥ 15 mmHg, with cardiac index < 2.0 L/ min.m², there was a relevant association with the increased percentage of myocardial fibrosis.

Conclusion

The percentage of the myocardial fibrosis mass indicates a non-invasive marker with promising perspectives in identifying patients with high risk factors for pulmonary hypertension.     

Assessment of Left Ventricular Mass and Hypertrophy by Cardiovascular Magnetic Resonance Imaging in Pediatric Hypertension

Cardiovascular magnetic resonance (CMR) imaging in adults is considered the gold standard for assessment of left ventricular mass (LVM) and left ventricular hypertrophy (LVH). The authors aimed to evaluate agreement of LVM measurements and LVH determination between echocardiography (ECHO) and CMR imaging in children with hypertension (HTN) confirmed by 24‐hour ambulatory blood pressure monitoring (ABPM). The children (n=22) underwent contemporaneous ECHO, CMR imaging, and ABPM. Patients had a mean body mass index of 30.9±7.5 (kg/m²), and 81.8% had severe HTN. LVM measured by ECHO was 189.6±62.1 g and by CMR imaging was 164.6±44.7 g (P<.0001). Bland‐Altman analysis revealed significant variability between ECHO and CMR imaging in the measurement of LVM. Interobserver error was higher with ECHO than with CMR imaging. ECHO had high sensitivity and low specificity in LVH determination. In conclusion, ECHO overestimates LVM and is less accurate in measuring LVM as compared with CMR imaging in children with HTN. Further prospective study using CMR imaging to assess LVM in children is warranted.     

存活心肌的磁共振研究

心肌梗死后存活心肌的诊断可以预测功能受损心肌在血运重建后的功能恢复。存活心肌检测方法很多,磁共振成像提供了不同的方法观察存活心肌。本文综述了磁共振延迟增强成像及舒张末期室壁厚度和小剂量多巴酚丁胺负荷磁共振成像在诊断存活心肌方面的进展。     

Pulmonary Regurgitation: Determining Severity by Echocardiography and Magnetic Resonance Imaging

Objective. Pulmonary regurgitation (PR) is common after repair of congenital heart disease involving the right ventricular outflow tract. Because PR results in chronic right ventricular volume overload and associated morbidity and mortality, accurate assessment of its severity is important. The aim of this study was to compare echocardiography with the gold standard of PR quantitation by magnetic resonance imaging (MRI) in a young population with repaired congenital heart disease. Design/Methods. Patients with congenital heart disease who had undergone right ventricular outflow tract reconstruction and/or pulmonary valve replacement and had an MRI within 3 months of an echocardiogram formed the study group. Echocardiographic indices were compared with MRI‐determined pulmonary regurgitant fraction (PRF) to determine the most accurate measurements to quantitate PR. Results. Of the 69 MRI/echocardiography pairs in 64 patients, 53 data sets were complete and used in the analysis. For the prediction of MRI PRF ≥20%, PR jet width/annulus ratio ≥0.5 demonstrated excellent sensitivity (94%), specificity (100%), positive predictive value (PPV 100%), and negative predictive value (NPV 82%). For the prediction of MRI PRF ≥40%, jet width/annulus ratio ≥0.7 and diastolic flow reversal in the branch pulmonary arteries showed useful sensitivity (92%), specificity (68%), PPV (76%), and NPV (88%). Conclusion. Pulmonary regurgitation jet width/annulus ratio combined with diastolic flow reversal is the most valuable echocardiographic measure for assessing PR severity after right ventricular outflow tract reconstruction or pulmonary valve replacement; however, this surrogate measure does not replace the importance of MRI evaluation.     

Initial Risk Assessment for Pulmonary Hypertension in Patients with COPD

Background  

Pulmonary hypertension (PH) is a comorbidity associated with increased mortality in chronic obstructive pulmonary disease (COPD) patients. It is not known which clinical markers are predictive of PH in COPD. The goal of this study was to develop a clinical tool to identify patients who should be sent for initial screening with echocardiography.     

Cardiac Magnetic Resonance Imaging for the Assessment of Myocardial Angiogenesis

Research in biology and applications of growth factors in coronary artery disease (CAD) has progressed considerably over recent years. Vascular endothelial growth factor and fibroblast growth factor-2 have been more successful in animal models of myocardial ischemia and Phase I studies than in placebo-controlled trials. However, cardiac magnetic resonance (CMR), with its higher sensitivity and specificity indices for identification of CAD, has not been extensively used in trials of angiogenic therapies. Data in animals and in patients suggest that CMR can reliably identify collateral vessels. Therefore, we hypothesize that CMR may depict collateralization induced by angiogenic therapy better than currently used nuclear perfusion imaging modalities. Versatility of the assessment of myocardial function and perfusion in one imaging session, combined with the noninvasive nature of the test, may considerably lower the cost of clinical trials. Use of CMR-derived surrogate end points may provide better risk stratification and assessment of efficacy in patients receiving growth factor therapy.     

Cardiovascular Magnetic Resonance Imaging For Assessment Of Cardiac Thrombus

Cardiac thrombus provides a substrate for embolic events and an indication for anticoagulant therapy. Cardiac magnetic resonance (CMR) imaging enables thrombus to be detected based on intrinsic tissue characteristics related to avascular tissue composition. Delayed enhancement CMR tissue characterization has been well validated for thrombus assessment using references of both pathology and clinical thromboembolic outcomes. Comparative studies have demonstrated CMR to yield improved thrombus detection compared to echocardiography, which typically detects thrombus based on anatomic appearance. Experimental studies have demonstrated the feasibility of targeted CMR contrast agents for assessing thrombus composition and chronicity. This review examines established and emerging literature on use of CMR for assessing cardiac thrombus.