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Regional left ventricular contractile dynamics in hypertrophic cardiomyopathy evaluated by magnetic resonance imaging
1Department of Cardiovascular Medicine, Okayama University, Japan.
Insights
Hypertrophic cardiomyopathy (HCM) affects regional myocardial function, with decreased function associated with increased hypertrophy. Compensatory mechanisms may increase function in unaffected segments.
Area of Science:
- Cardiology
- Medical Imaging
- Biomedical Engineering
Background:
- Hypertrophic cardiomyopathy (HCM) is a complex cardiac condition characterized by left ventricular hypertrophy.
- Assessing regional myocardial function is crucial for understanding HCM pathophysiology and progression.
Purpose of the Study:
- To evaluate regional myocardial function in patients with hypertrophic cardiomyopathy (HCM) using cine magnetic resonance imaging.
- To correlate changes in systolic wall thickening (%WT) and segmental wall area (%AR) with the degree of hypertrophy in HCM.
Main Methods:
- Cine magnetic resonance imaging (MRI) was used to assess systolic wall thickening (%WT) and percent change of segmental wall area (%AR).
- Short-axis left ventricular images were analyzed in five segments from base to apex.
- Participants included 23 healthy volunteers and 40 patients with HCM, stratified by end-diastolic wall thickness.
Main Results:
- In healthy volunteers, myocardial shortening was greater at the apex than the base.
- In HCM patients, %WT and %AR at the base were higher in milder hypertrophy (group 2a) but significantly lower in severe hypertrophy (group 2c).
- Apical %WT and %AR were significantly reduced in group 2c compared to other groups and controls.
Conclusions:
- Regional myocardial function in HCM is impaired and inversely related to the degree of hypertrophy.
- Severe hypertrophy in HCM is associated with reduced function at both base and apex.
- Increased function in non-hypertrophied segments may represent a compensatory response.
Abstract:
To assess regional myocardial function in hypertrophic cardiomyopathy (HCM), we examined systolic wall thickening (%WT) and percent change of segmental wall area (%AR) by cine magnetic resonance imaging. We studied 23 normal volunteers without evidence of heart disease (group 1) and 40 patients with HCM (group 2). Short-axis images of the left ventricle were recorded at the base and the apex, and were divided into five segments. There were no significant differences in %WT and %AR among the segments in group 1, while %WT and %AR at the apex were higher than values for corresponding segments at the base. The patients with HCM (group 2) were classified into three groups according to end-diastolic wall thickness: group 2a, less than 12 mm; group 2b, 12-15 mm and group 2c, greater than 15 mm. Both the %WT and %AR at the base were significantly higher in group 2a than in the other groups, but were significantly lower in group 2c than in group 1 or group 2a (%WT and %AR in groups 1, 2a, 2b, and 2c respectively: 51 +/- 29 and 19 +/- 17; 83 +/- 40 and 34 +/- 18; 47 +/- 38 and 16 +/- 14; and 32 +/- 21 and 9 +/- 8). Both %WT (40 +/- 24) and %AR (14 +/- 12) at the apex were significantly lower in group 2c than in the other groups (87 +/- 45 and 38 +/- 31 in group 1; 89 +/- 41 and 39 +/- 31 in group 2a; and 61 +/- 27 and 24 +/- 15 in group 2b). Myocardial shortening in the normal volunteers was greater at the apex than at the base. In patients with HCM, regional myocardial function was decreased in association with the degree of hypertrophy, with the wall function of the normal segments appearing to be increased in a possible compensatory mechanism.