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Detection of regional left ventricular asynchrony in obstructive hypertrophic cardiomyopathy by magnetic resonance
E Schwammenthal1, T Wichter, K Joachimsen
1Department of Cardiology, Hospital of the Westfälische Wilhelms, University of Münster, Germany.
Insights
Cine magnetic resonance imaging revealed significant left ventricular asynchrony in patients with hypertrophic cardiomyopathy (HC). This regional dysfunction, particularly in wall thickening, contributes to impaired diastolic function despite normal global systolic function.
Area of Science:
- Cardiology
- Medical Imaging
- Biomedical Engineering
Background:
- Obstructive hypertrophic cardiomyopathy (HC) is characterized by abnormal thickening of the left ventricle.
- Assessing regional left ventricular function is crucial for understanding diastolic dysfunction in HC.
Purpose of the Study:
- To analyze global and regional left ventricular function in patients with obstructive HC using cine magnetic resonance imaging (MRI).
- To identify potential correlations between cardiac structure, systolic function, and diastolic dysfunction in HC.
Main Methods:
- Cine magnetic resonance imaging (MRI) was employed to evaluate left ventricular function in seven HC patients and ten healthy controls.
- Key parameters analyzed included left ventricular mass index, end-diastolic volume index, mass-to-volume ratio, ejection fraction, and time to maximal wall thickening.
Main Results:
- Patients with HC exhibited higher left ventricular mass index and mass-to-volume ratio, with lower end-diastolic volume index compared to controls.
- Despite normal global systolic function and higher ejection fraction, HC patients showed significant regional left ventricular asynchrony in wall thickening.
- Asynchrony was observed both between different regions (basal vs. apical) and within regions (basal) of the left ventricle in HC patients.
Conclusions:
- Cine MRI effectively detects regional left ventricular asynchrony in patients with obstructive HC.
- This asynchrony is a significant contributor to impaired diastolic function, even when global systolic function remains normal.
- Findings highlight the utility of advanced MRI techniques in characterizing complex cardiac mechanics in HC.
Abstract:
Cine magnetic resonance imaging was used to analyze global and regional left ventricular function in seven patients with obstructive hypertrophic cardiomyopathy (HC) and 10 normal subjects. In patients with HC a 38% higher left ventricular mass index (106.4 +/- 20.2 gm/m2 vs 77.0 +/- 16.1 gm/m2, p < 0.005) associated with a lower end-diastolic volume index (44.9 +/- 8.9 ml/m2 vs 58.3 +/- 9.0 ml/m2, p < 0.005) resulted in an 85% higher mass-to-volume ratio (2.4 +/- 0.52 vs 1.3 +/- 0.57, p < 0.0005). Stroke volume did not differ significantly, whereas ejection fraction was higher (80.4% +/- 6.5% vs 65.4% +/- 7.2%, p < 0.0005) in patients with HC. Although early diastolic filling fraction was smaller in patients with HC (61.0% +/- 22.8% vs 68.4% +/- 14.6%), the difference did not reach significance because of substantial variability. In patients with HC (in contrast to normal subjects) the time to maximal wall thickening was shorter (p < 0.025) in the hypertrophied basal region of the ventricle (223 +/- 42 msec) than in the apical region (267 +/- 35 msec), reflecting asynchrony between these regions. Additionally, in patients with HC the standard deviation of the time to maximal wall thickening in the basal region was significantly higher when compared with that of normal subjects (40.0 +/- 24 msec vs 16.9 +/- 17 msec, p < 0.0005), reflecting asynchrony even within one region. Thus magnetic resonance imaging can detect regional left ventricular asynchrony, an important cause of impaired diastolic function, in patients with HC and normal global systolic function.(ABSTRACT TRUNCATED AT 250 WORDS)