Biomedical subjects
James C Moon
Publications and source records attributed to James C Moon.
Ventricular fibrosis suggested by cardiovascular magnetic resonance in adults with repaired tetralogy of fallot and its relationship to adverse markers of clinical outcome.
BACKGROUND: Late morbidity and mortality remain problematic after repair of tetralogy of Fallot (TOF). We hypothesized that fibrosis detected by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) would be present in adults with repaired TOF and would be related to adverse markers of outcome. METHOD AND RESULTS: LGE was scored in the right and left ventricles (RV and LV) of 92 adult patients who had undergone TOF repair. RV LGE was seen in all patients at surgical sites located in the outflow tract (99%) or the site of ventricular septal defect patching (98%) and in the inferior RV insertion point (79%) and trabeculated myocardium (24%). LV LGE (53%) was located at the apex consistent with apical vent insertion (49%), in the inferior or lateral wall consistent with infarction (5%), or in other areas (8%). Patients with supramedian RV LGE score were older (38 versus 27 years, P<0.001) and more symptomatic (38% versus 8% in New York Heart Association class II or greater, P=0.001), had increased levels of atrial natriuretic peptide (7.3 versus 4.9 pmol/L, P=0.041), and had a trend to higher brain natriuretic peptide (12.3 versus 7.2 pmol/L, P=0.086), exercise intolerance (maximum VO2 24 versus 28 mL.min(-1).kg(-1), P=0.021), RV dysfunction (RV end-systolic volume 61 versus 55 mL/m2, P=0.018; RV ejection fraction 50% versus 56%, P=0.007), and clinical arrhythmia (26% versus 10%, P=0.039). Non-apical vent LV LGE also correlated with markers of adverse outcome. In a multivariate model, RV LGE remained a predictor of arrhythmia. CONCLUSIONS: RV and LV LGE were common after TOF repair and were related to adverse clinical markers, including ventricular dysfunction, exercise intolerance, and neurohormonal activation. Furthermore, RV LGE was significantly associated with clinical arrhythmia.
The histological basis of late gadolinium enhancement cardiovascular magnetic resonance in a patient with Anderson-Fabry disease.
Anderson-Fabry Disease (AFD) is a storage disease that mimics hypertrophic cardiomyopathy. Late gadolinium enhancement (LGE) by cardiovascular magnetic resonance occurs in approximately 50% of patients in the basal inferolateral LV wall, but how an intracellular storage disease causes focal LGE is unknown. We present a whole-heart histological validation that LGE is caused by focal myocardial collagen scarring. This scarring may be the substrate for electrical re-entry and sudden arrhythmic death. The reasons for this distribution of fibrosis are unclear, but may reflect inhomogeneous left ventricular wall stress.
Stress, emotion and the heart: tako-tsubo cardiomyopathy.
Tako-tsubo cardiomyopathy is a cardiac syndrome precipitated by profound emotional stress and anxiety, particularly in middle-aged women. It presents as a mimic of acute myocardial infarction, but coronary angiography shows normal coronary arteries and a characteristic left ventriculogram resembling an "octopus pot". The condition seems to have a favourable prognosis. Initially described in Japan, and with many names in the literature, it is being increasingly recognised in the West owing to early coronary angiography and primary coronary intervention, accounting for up to 1 in 30 primary cases of angioplasty in some institutions. A typical case is described, and the clinical features, pathophysiology and management reviewed.
Late gadolinium enhancement cardiovascular magnetic resonance of the systemic right ventricle in adults with previous atrial redirection surgery for transposition of the great arteries.
BACKGROUND: Patients treated for transposition of the great arteries by atrial redirection surgery have a right ventricle (RV) that sustains systemic pressures long term. Late RV dysfunction occurs in these patients; the reasons for this are unclear, but myocardial fibrosis may be important. Myocardial fibrosis can be visualized by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR). We hypothesized that LGE would be present in the systemic RV and relate to adverse clinical features. METHODS AND RESULTS: We performed CMR on 36 consecutive adult patients (mean age, 27 years) after atrial redirection surgery for transposition of the great arteries. Late gadolinium RV enhancement was seen in 22 patients (61%) with various patterns. Patients with RV LGE were older (30 versus 22 years; P<0.001) and had increased RV end-systolic volume index (43 versus 35 mL/m2; P=0.03), decreased RV ejection fraction (57% versus 62%; P=0.02), increased QRS duration (108 versus 97 ms; P=0.01), and increased QT dispersion (93 versus 71 ms; P=0.002). The extent of LGE correlated with age (r=0.59, P<0.001) and QRS duration (r=0.67, P<0.001) and inversely with RV ejection fraction (r=-0.76, P<0.001). The incidence of documented arrhythmia and/or syncope (10 of 36) was significantly higher in the late gadolinium-positive group (9/22 versus 1/14; P=0.03). CONCLUSIONS: LGE CMR suggestive of myocardial fibrosis occurs in the systemic RV of patients after atrial redirection surgery. The extent of LGE correlates with age, ventricular dysfunction, electrophysiological parameters, and clinical events, suggesting prognostic importance that merits further investigation.
Late recurrence of outflow tract obstruction seven years after septal ablation in hypertrophic cardiomyopathy.
We present a case of late recurrence of outflow tract obstruction 7 years after successful septal ablation in hypertrophic cardiomyopathy. In addition the debate over maximal versus minimal treatment is discussed.
Comparison of hybrid echo-planar imaging and FLASH myocardial perfusion cardiovascular MR imaging.
The purpose of this study was to compare fast single-shot gradient-echo (FLASH) and hybrid echo-planar imaging (EPI) magnetic resonance (MR) technologies regarding the relative contrast-to-noise ratio (CNR), spatiotemporal resolution, size of inducible perfusion defects, and presence of artifacts in patients with coronary artery disease (CAD). Fifteen patients with CAD underwent rest and adenosine stress gadolinium first-pass perfusion cardiovascular MR examinations with EPI and FLASH. The study was approved by the local ethics committee, and each subject gave written informed consent. The spatial resolution of the two sequences was made similar in nine patients, and the temporal resolution was made similar in six. The images were assessed for CNR, artifact, and size of inducible perfusion defects. The CNR was significantly higher with the EPI sequence, whether matched for spatial (32 vs 22 [46%], P < .001) or temporal (35 vs 23 [51%], P < .001) resolution. There was no significant difference in scoring for artifact or area and transmural extent of inducible perfusion defects with EPI and FLASH, whether matched for temporal or spatial resolution. Further work is warranted to determine the relative diagnostic accuracy of the two techniques.
Frequency and clinical expression of cardiac troponin I mutations in 748 consecutive families with hypertrophic cardiomyopathy.
OBJECTIVES: The aim of this study was to evaluate the potential utility of genetic diagnosis in clinical management of families with hypertrophic cardiomyopathy (HCM) caused by mutations in the gene for cardiac troponin I (TNNI3). BACKGROUND: Knowledge about the clinical disease expression of sarcomeric gene mutations in HCM has predominantly been obtained by investigations of single individuals (probands) or selected families. To establish the role of genetic diagnosis in HCM families, systematic investigations of probands and their relatives are needed. METHODS: Cardiac troponin I was investigated by direct sequencing and fluorescent (F)-SSCP analysis in 748 consecutive HCM families. Relatives of HCM probands with TNNI3 mutations were invited for cardiovascular and genetic assessment. RESULTS: The prevalence of TNNI3 mutations was 3.1%. Mutations appeared to cluster in exons 7 and 8. A total of 100 mutation carriers were identified in 23 families with 13 different mutations (6 novel). Disease penetrance was 48%. Patients were diagnosed from the second to eighth decade of life. The morphologic spectrum observed represented a wide range of HCM. Two offspring of clinically unaffected mutation carriers were resuscitated from cardiac arrest, and an additional four individuals died suddenly as their initial presentation. Six individuals experienced other disease-related deaths. CONCLUSIONS: The clinical expression of TNNI3 mutations was very heterogeneous and varied both within and between families with no apparent mutation- or gene-specific disease pattern. The data suggest that disease development may be monitored by regular assessment of cardiac symptoms and electrocardiographic abnormalities. Genetic diagnosis of TNNI3 is valuable in identifying clinically unaffected mutation carriers at risk of disease development and facilitates accurate management and counseling.
Interstudy reproducibility of right ventricular volumes, function, and mass with cardiovascular magnetic resonance.
BACKGROUND: Cardiovascular magnetic resonance (CMR) has shown excellent results for interstudy reproducibility in the assessment of left ventricular (LV) parameters. However, interstudy reproducibility data for the more complex-shaped right ventricle in a large study group have not yet been reported. We sought to determine the interstudy reproducibility of measurements of right ventricular (RV) volumes, function, and mass with CMR and compare it with correspondent LV values. METHODS: Sixty subjects (47 men; 20 healthy volunteers, 20 patients with heart failure, 20 patients with ventricular hypertrophy) underwent 2 CMR studies for assessment of RV measurements with a minimum time interval between each study. RESULTS: The overall interstudy reproducibility (range between groups) for the RV was 6.2% (4.2%-7.8%) for end-diastolic volume, 14.1% (8.1%-18.1%) for end-systolic volume, 8.3% (4.3%-10.4%) for ejection fraction (EF), and 8.7% (7.8%-9.4%) for RV mass. RV reproducibility was not as good as for the LV for all measures in all 3 groups, but this was only statistically significant for EF (P <.01). CONCLUSIONS: CMR showed good interstudy reproducibility for RV function parameters in healthy subjects, patients with heart failure, and patients with hypertrophy, which suggests that CMR is reliable for serial RV assessment. These data can be used to power sample sizes for longitudinal research studies of RV volume and function. The reproducibility values were similar to, but generally lower than, the reproducibility values for the LV in the same study population, which indicates that sample sizes for RV studies are in general larger than those for LV studies.
Cardiovascular magnetic resonance of asymptomatic myocardial infarction.
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Combined long- and short-axis myocardial perfusion cardiovascular magnetic resonance.
PURPOSE: To date, myocardial perfusion cardiovascular magnetic resonance (CMR) has been reported in single and multiple short-axis slices. Three short-axis planes can assess 16 segments of the standard 17-segment myocardial model, but this approach fails to assess the ventricular apex that requires at least one long-axis plane. We therefore evaluated the feasibility and benefit of combined long- and short-axis perfusion CMR to enable complete 17 segments coverage for comprehensive myocardial perfusion assessment. METHODS AND MATERIALS: Using a hybrid echo planar imaging (EPI) sequence, we performed rest and adenosine stress first-pass perfusion CMR studies with 3 short-axis (basal, mid, apical) planes, and additional long-axis planes in the same cardiac cycle in a broad range of cardiology patients. RESULTS: Perfusion CMR was performed in 53 consecutive patients using the combined short-long-axis imaging protocol. Twenty-nine of those studied had known or suspected coronary artery disease (CAD), 18 hypertrophic cardiomyopathy, and 6 suspected microvascular perfusion abnormalities. In 39 patients (70%), it was possible to acquire 5 slices at rest and stress including both the horizontal and vertical long axes. In 15 patients (27%), only one long-axis could be acquired, and in 2 patients (5%) only 3 slices (short axis) could be obtained. However, in none of the patients with known or suspected CAD was apical ischemia demonstrated by the long-axis views, despite apical ischemia having been demonstrated with recent SPECT studies in 8 of these patients. CONCLUSION: Rest-stress myocardial perfusion CMR is able to achieve complete segmental coverage of the myocardium using the combined short-long axis approach using an EPI sequence in 97% of a long series of consecutive cardiology patients, while maintaining excellent spatial resolution. However, the long-axis views were not found to be able to demonstrate inducible perfusion defects in the apex.
Cardiovascular magnetic resonance of imminent cardiac tamponade due to postpericardiotomy syndrome.
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Cardiac pseudotumor: tissue characterization by cardiovascular magnetic resonance.
We present serial cardiovascular magnetic resonance (CMR) in a case of cardiac pseudotumor (inflammatory myofibroblastic tumor). The diagnosis proved difficult and was helped by myocardial tissue characterization using CMR. Intrinsic contrast and extrinsic contrast (using gadolinium-DTPA perfusion, early and late imaging) differentiated between normal and pathological tissues and demonstrated the changes in properties of cardiac pseudotumor over time. The case illustrates the versatility of CMR in tissue characterization, which is unavailable by other cardiac imaging modalities.