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Influence of drug therapy on myocardial hypertrophy in left ventricular failure
1University Department of Cardiovascular Studies, General Infirmary, Leeds, England.
Insights
Terminal heart failure involves eccentric ventricular hypertrophy, where sarcomeres replicate in series, impairing contractility. Adequate coronary blood supply is crucial for this hypertrophy, impacting prognosis and sudden death risk.
Area of Science:
- Cardiology
- Heart Failure Pathophysiology
Background:
- Terminal volume-overload heart failure is characterized by eccentric ventricular hypertrophy.
- Mechanisms driving this hypertrophy are not well understood.
- Hypertrophied myocytes exhibit reduced contractile function, which is reversible.
Purpose of the Study:
- To explore the mechanisms of eccentric ventricular hypertrophy in heart failure.
- To investigate the role of coronary blood supply in hypertrophy development.
- To understand the implications of hypertrophy on prognosis and sudden death.
Main Methods:
- Analysis of sarcomere replication in series due to increased diastolic wall stress.
- Assessment of myocyte contractile function and its reversibility.
- Evaluation of coronary blood supply's role in hypertrophy.
Main Results:
- Increased diastolic wall stress causes sarcomere replication in series, leading to eccentric hypertrophy.
- Myocyte contractility is intrinsically depressed but can be restored.
- Adequate coronary blood supply is essential for appropriate hypertrophy development.
Conclusions:
- Eccentric hypertrophy in heart failure is driven by increased wall stress and requires sufficient coronary perfusion.
- This hypertrophy carries a poor prognosis and is linked to sudden arrhythmic death.
- Urgent reduction of preload and afterload, while maintaining coronary perfusion, is critical.
Abstract:
The terminal phases of volume-overload heart failure are characterised by eccentric ventricular hypertrophy. Relatively little attention has been directed to exploring the mechanisms involved in this development. The increase in diastolic wall stress leads to replication of the sarcomeres in series. The hypertrophied myocytes has a defective contractile ability that is due to an intrinsic depression of contractility; this is restored when failure is reversed. The development of appropriate hypertrophy is dependent upon adequacy of the coronary blood supply to the failing myocytes. Reduction of preload and afterload can be expected to be more effective in reducing systolic wall stress, and hence myocardial oxygen demands, in eccentric hypertrophy than in the nonfailing heart with concentric hypertrophy. However, there is no information available on the influence of anti-heart-failure drugs on the myocardial hypertrophy associated with severe volume-overload failure. The presence of such hypertrophy carries an ominous prognosis and may be associated with the high incidence of arrhythmic sudden deaths. The detection of myocardial hypertrophy in the patient with failure emphasises the urgency of adequate reduction of the elevated preload and afterload without impairment of the coronary perfusion gradient.