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Effect of changes in contractility on the index of myocardial performance in the dysfunctional left ventricle

Steven J Lavine1

  • 1Department of Medicine, Division of Cardiology, Wayne State University and University of Florida/Jacksonville, Detroit, Michigan and Jacksonville, Florida, USA. steven.lvine@jax.ufl.edu

Cardiovascular Ultrasound
|November 18, 2006
PubMed

Insights

Improving contractility with dobutamine and digoxin reduced the index of myocardial performance in dogs with left ventricular dysfunction. These findings offer insights into heart failure treatments.

Area of Science:

  • Cardiology
  • Physiology

Background:

  • The index of myocardial performance (IMP) is a prognostic indicator in heart conditions.
  • IMP is influenced by preload and afterload, but its response to contractility changes in left ventricular dysfunction is not fully understood.

Purpose of the Study:

  • To investigate the effect of enhanced contractility on the index of myocardial performance and its components in a canine model of chronic left ventricular dysfunction.

Main Methods:

  • Chronic left ventricular dysfunction was induced in 10 canines.
  • Echocardiography and Doppler imaging were used to assess cardiac function.
  • Contractility was augmented using dobutamine infusion and oral digoxin administration.

Main Results:

  • Left ventricular dysfunction led to reduced ejection fraction and increased IMP.
  • Dobutamine and digoxin both improved ejection fraction and reduced IMP.
  • Both agents shortened isovolumic contraction time and lengthened the diastolic filling period.

Conclusions:

  • Increased inotropy via dobutamine and digoxin effectively reduced IMP in canine models with left ventricular dysfunction.
  • Digoxin's effects, including shortened isovolumic contraction time and improved diastolic filling, may explain its efficacy in heart failure management.
Abstract

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