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Clinical assessment of left ventricular systolic function by force-length and stress-shortening relationships
1Department of Internal Medicine, Osaka Medical College, Takatsuki, Japan.
Insights
This study shows that stress-shortening is a better measure than force-length for assessing left ventricular (LV) systolic function in heart disease patients. It helps distinguish between different heart conditions, even with heart failure.
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Biomedical Engineering
Background:
- Left ventricular (LV) systolic function is crucial for cardiovascular health.
- Hypertensive heart disease (HHD), hypertrophic cardiomyopathy (HCM), and dilated cardiomyopathy (DCM) represent distinct cardiac pathologies.
- Understanding LV adaptation to pressure and volume overload is key to managing heart failure.
Purpose of the Study:
- To compare the efficacy of force-length and stress-shortening parameters in assessing LV systolic function across various cardiac conditions.
- To differentiate between HHD, HCM, DCM, and volume overload heart (VOH) patients using these functional parameters.
- To evaluate the utility of these parameters in identifying early signs of heart failure.
Main Methods:
- Assessed LV systolic function in 5 patient groups (HHD, HCM, DCM, VOH, normal subjects) and controls.
- Utilized a two-dimensional framework analyzing force-length (end-systolic stress-end-systolic volume index) and stress-shortening (mid-systolic stress-ejection fraction).
- Employed quadratic discriminant analysis for group discrimination.
Main Results:
- Force-length and stress-shortening analyses showed HHD and normal subjects were indistinguishable.
- All other groups (HCM, DCM, VOH) were well-discriminated by both methods.
- Subgroups of DCM and VOH with heart failure were distinguishable by stress-shortening but not force-length.
Conclusions:
- LV systolic function and afterload remain normal under pressure/volume overload until heart failure symptoms manifest, mediated by compensatory hypertrophy.
- Stress-shortening is a more clinically applicable parameter than force-length for analyzing LV systolic function in practice.
- This highlights the value of stress-shortening in differentiating cardiac conditions and assessing functional status.
Abstract:
Left ventricular (LV) systolic function was assessed in patients with hypertensive heart disease (HHD, n = 30), hypertrophic cardiomyopathy (HCM, n = 27), dilated cardiomyopathy (DCM, n = 25), volume overload heart (VOH, n = 31) and normal subjects (NS, n = 32) in the two-dimensional framework of force-length (end-systolic stress-end-systolic volume index) and stress-shortening (mid-systolic stress-ejection fraction). Quadratic discriminant analysis revealed that the ellipses of confidence of HHD and normal subjects were in the same place with regard to both force-length and stress-shortening, while all other groups were well-discriminated. Three subgroups of patients, those with DCM with mild heart failure and those with VOH (with and without heart failure), were easily distinguishable on the basis of stress-shortening, but not on the basis of force-length measurements. It is concluded that LV systolic function and afterload are maintained within the normal range under pressure and volume overload until symptoms of heart failure appear via the mechanism of compensatory hypertrophy. Stress-shortening appears to be a more useful parameter than force-length for the analysis of LV systolic function in clinical practice.