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Intramural mechanics in hypertrophic cardiomyopathy: functional mapping with strain-rate MR imaging
G M Beache1, V J Wedeen, R M Weisskoff
1MGH-NMR Center, Department of Radiology, Massachusetts General Hospital, Charlestown 02129, USA.
Insights
A new scalar strain rate (SR) metric reveals abnormal heart mechanics in hypertrophic cardiomyopathy (HCM). This contractile activity measure shows potential for objectively tracking HCM progression and disease severity.
Area of Science:
- Cardiology
- Biomedical Engineering
- Medical Imaging
Background:
- Hypertrophic cardiomyopathy (HCM) is a complex cardiac disease.
- Understanding intramural mechanics is crucial for assessing HCM.
- Existing metrics may not fully capture contractile dysfunction.
Purpose of the Study:
- To introduce and evaluate a novel scalar strain rate (SR) parameter.
- To characterize systolic and diastolic intramural mechanics in HCM.
- To correlate SR with clinical parameters and disease severity.
Main Methods:
- Velocity-encoded echo-planar MR imaging was performed on healthy subjects and HCM patients.
- A scalar strain rate (SR) parameter was calculated.
- SR was compared with regional wall thickness and New York Heart Association (NYHA) functional class.
Main Results:
- Normal SR patterns showed regional uniformity and transmural gradients.
- HCM patients exhibited increased diastolic SR heterogeneity.
- Regional diastolic SR correlated significantly with regional wall thickness (r = .785, P = .0001).
- SR deficit scores showed a trend correlating with NYHA class.
Conclusions:
- Scalar strain rate (SR) characterization offers a new metric for assessing cardiac mechanics.
- SR may serve as an objective measure for monitoring the disease course in HCM.
- This technique has potential for improved diagnosis and management of HCM.
Purpose:
To characterize systolic and diastolic intramural mechanics in hypertrophic cardiomyopathy (HCM) with a new metric of contractile activity.
Materials And Methods:
Eleven healthy subjects and eight patients with HCM underwent velocity-encoded echo-planar magnetic resonance (MR) imaging (6-8-frame gated breath-hold movies, 3 x 3-mm resolution). A scalar strain rate (SR) parameter was compared with wall thickness and symptoms.
Results:
The normal pattern of SR included regional uniformity, a monotonically increasing subepicardial to subendocardial gradient, and minimum transmural shear rate. In HCM, heterogeneity of SRs increased in diastole. Regional diastolic SR correlated with regional wall thickness (r = .785, P = .0001). Interobserver global SR assignment agreed in seven of eight patients. All four patients with New York Heart Association class 1 disease had a low global SR deficit score, whereas three of four patients with class 2 or 3 disease had a high SR deficit score (Spearman r = .775, P = .187).
Conclusion:
SR characterization may provide an objective measure of disease course in HCM.