Document Detail

Myocardial structural, perfusion, and metabolic correlates of left bundle branch block mechanical derangement in patients with dilated cardiomyopathy: a tagged cardiac magnetic resonance and positron emission tomography study.
MedLine Citation:
PMID:  20463209     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Left bundle branch block (LBBB) influences on regional left ventricular (LV) structure, perfusion, and metabolism have not yet been thoroughly investigated in dilated cardiomyopathy patients.
METHODS AND RESULTS: Eleven dilated cardiomyopathy patients with LBBB (mean+/-SD age, 62+/-11 years; LV ejection fraction, 35+/-8%) and 7 dilated cardiomyopathy patients without LBBB (mean+/-SD age, 58+/-9 years; LV ejection fraction, 37+/-10%) were studied by cardiac magnetic resonance and positron emission tomography. The left ventricle was divided in 3 regions: septum, adjacent (anterior-inferior walls), and lateral. Regional midwall circumferential strain, maximum shortening, and strain rate were obtained from tagged cardiac magnetic resonance. The systolic stretch index was calculated as positive strain rate (stretching) divided by total strain rate. Myocardial metabolic rate of glucose and resting and hyperemic myocardial blood flow were quantified by 2-[(18)F]fluoro-2-deoxyglucose and [(13)N]ammonia positron emission tomography, respectively. Compared with non-LBBB patients, LBBB patients showed a highly inhomogeneous systolic deformation pattern that changed gradually, moving from a discoordinate [(systolic stretch index, 0.485 (0.284)] and poorly contracting (maximum shortening, -1.14+/-0.96%) septum to a coordinate [systolic stretch index, 0.002 (0.168)] and strongly contracting (maximum shortening, -13.63+/-2.58%) lateral region (both P<0.0001). This pattern was closely matched to the myocardial metabolic rate of glucose, disclosing lowest, intermediate, and highest values in the septum, adjacent, and lateral regions, respectively (P<0.0001). Septal-to-lateral thickness ratio was lower in LBBB than in non-LBBB patients (P=0.03). In both groups, the LV distribution of resting and hyperemic myocardial blood flow and myocardial blood flow reserve did not differ significantly.
CONCLUSIONS: In dilated cardiomyopathy patients, the extensive LV contraction abnormalities induced by LBBB cause regional myocardial metabolic and structural remodeling, without consistent changes in blood flow.
Pier Giorgio Masci; Martina Marinelli; Marcello Piacenti; Valentina Lorenzoni; Vincenzo Positano; Massimo Lombardi; Antonio L'Abbate; Danilo Neglia
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Publication Detail:
Type:  Journal Article     Date:  2010-05-12
Journal Detail:
Title:  Circulation. Cardiovascular imaging     Volume:  3     ISSN:  1942-0080     ISO Abbreviation:  Circ Cardiovasc Imaging     Publication Date:  2010 Jul 
Date Detail:
Created Date:  2010-07-21     Completed Date:  2010-08-12     Revised Date:  2011-09-06    
Medline Journal Info:
Nlm Unique ID:  101479935     Medline TA:  Circ Cardiovasc Imaging     Country:  United States    
Other Details:
Languages:  eng     Pagination:  482-90     Citation Subset:  IM    
Fondazione G. Monasterio-Regione Toscana/CNR, Scuola Superiore Sant'Anna, and Institute of Clinical Physiology/CNR, Pisa, Italy.
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MeSH Terms
Analysis of Variance
Blood Flow Velocity
Bundle-Branch Block / metabolism,  physiopathology*,  radionuclide imaging
Cardiomyopathy, Dilated / metabolism,  physiopathology*,  radionuclide imaging
Chi-Square Distribution
Coronary Circulation
Fluorodeoxyglucose F18 / diagnostic use
Magnetic Resonance Imaging / methods*
Middle Aged
Nitrogen Radioisotopes / diagnostic use
Positron-Emission Tomography*
Prospective Studies
Radiopharmaceuticals / diagnostic use
Statistics, Nonparametric
Stroke Volume
Reg. No./Substance:
0/Nitrogen Radioisotopes; 0/Radiopharmaceuticals; 63503-12-8/Fluorodeoxyglucose F18

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