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Force-frequency relation in patients with left ventricular hypertrophy and failure
1Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, Maryland 21287, USA.
Basic Research in Cardiology
|December 2, 1998
Summary
Patients with ventricular hypertrophy and heart failure experience reduced systolic function as heart rate increases. This dysfunction, linked to excitation-contraction coupling, limits cardiovascular reserve and causes exertional intolerance.
Area of Science:
- Cardiology
- Physiology
Background:
- Ventricular hypertrophy (LVH) is associated with impaired cardiac function and congestive heart failure symptoms.
- Patients with LVH often experience limited cardiovascular reserve and exertional intolerance.
Purpose of the Study:
- To investigate the impact of increasing heart rate on systolic function in patients with LVH and heart failure.
- To explore the underlying mechanisms of impaired cardiac force-frequency response in LVH.
Main Methods:
- Assessed systolic contractile enhancement with increasing heart rate.
- Evaluated diastolic function, post-rest potentiation, recirculation fraction, and mechanical restitution.
- Examined ventriculo-vascular coupling efficiency in LVH hearts.
Main Results:
- Demonstrated a loss of systolic contractile enhancement with increased heart rate in LVH patients.
- Observed no worsening of diastolic function, suggesting mechanisms beyond ischemia.
- Identified abnormalities in excitation-contraction coupling and impaired ventriculo-vascular coupling.
Conclusions:
- Dysfunctional cardiac force-frequency behavior contributes to limited cardiovascular reserve in LVH.
- Abnormalities in excitation-contraction coupling, not SR Ca2+ release, are implicated.
- Enhancing the force-frequency response may improve exercise capacity in LVH patients.