title: [Mechanical function is normal in remanent myocardium during the healing period of myocardial infarction--despite congestive heart failure].
abstract: OBJECTIVE
  The temporal relation between ventricular dysfunction (VD) after myocardial infarction (MI) and remanent myocardium mechanics is not yet clear. The present work investigated--through Doppler echocardiography (ECHO)--ventricular function in rats with extensive MI, as well as the mechanical function of papillary muscles (PM) at the end of the healing period.
  
  
  METHODS
  ECHO and PM of 9 Wistar rats (MI) were studied against 9 controls (C) three weeks after LV myocardial infarction. The following were determined: developed tension (DT) and its first negative and positive derivative, time-to-peak tension (TPT), resting tension (RT), and relaxation time at 50% of DT at 0.5, 1.0, 1.5, 2.0 and 2.5 calcium concentrations (mM). Tetanic contractions were carried out after ryanodine administration at 1.5, 2.5 and 5.0 calcium concentrations.
  
  
  RESULTS
  VD was characterized by ECHO, with marked abnormality of diastolic volume and LV and ejection fraction in addition to clear restrictive pattern of blood flow through the mitral valve. No significant difference was found in myocardial mechanics data either for MI or for C rats.
  
  
  CONCLUSIONS
  The heart failure (HF) reported by MI rats with > 40% MI at the end of the healing period is not myocardial function dependent. Chamber structural changes and lower population of myocites should base VD and HF.
authors.affiliation: Universidade Federal de São Paulo, São Paulo, SP.
authors.forename: Alessandra P O N
authors.initials: AP
authors.lastname: Peron
authors.forename: Roberto M
authors.initials: RM
authors.lastname: Saraiva
authors.forename: Ednei L
authors.initials: EL
authors.lastname: Antonio
authors.forename: Paulo José Ferreira
authors.initials: PJ
authors.lastname: Tucci
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003971:Diastole; D015150:Echocardiography, Doppler; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology*; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D013599:Systole; D016277:Ventricular Function, Left / Q000502:physiology*; D020257:Ventricular Remodeling