title: Integrated wall stress: a new methodological approach to assess ventricular workload and myocardial contractile reserve.
abstract: BACKGROUND
  Wall stress is a useful concept to understand the progression of ventricular remodeling. We measured cumulative LV wall stress throughout the cardiac cycle over unit time and tested whether this "integrated wall stress (IWS)" would provide a reliable marker of total ventricular workload.
  
  
  RESULTS
  We applied IWS to mice after experimental myocardial infarction (MI) and sham-operated mice, both at rest and under dobutamine stimulation. Small infarcts were created so as not to cause subsequent overt hemodynamic decompensation. IWS was calculated over one minute through simultaneous measurement of LV internal diameter and wall thickness by echocardiography and LV pressure by LV catheterization. At rest, the MI group showed concentric LV hypertrophy pattern with preserved LV cavity size, LV systolic function, and IWS comparable with the sham group. Dobutamine stimulation induced a dose-dependent increase in IWS in MI mice, but not in sham mice; MI mice mainly increased heart rate, whereas sham mice increased LV systolic and diastolic function. IWS showed good correlation with a product of peak-systolic wall stress and heart rate. We postulate that this increase in IWS in post-MI mice represents limited myocardial contractile reserve.
  
  
  CONCLUSIONS
  We hereby propose that IWS provides a useful estimate of total ventricular workload in the mouse model and that increased IWS indicates limited LV myocardial contractile reserve.
authors.affiliation: Nemours Cardiac Center and Nemours Biomedical Research, Alfred I, duPont Hospital for Children, 1600 Rockland Rd, Wilmington, DE 19103, USA.
authors.forename: Hailong
authors.initials: H
authors.lastname: Dong
authors.forename: Heather
authors.initials: H
authors.lastname: Mosca
authors.forename: Erhe
authors.initials: E
authors.lastname: Gao
authors.forename: Robert E
authors.initials: RE
authors.lastname: Akins
authors.forename: Samuel S
authors.initials: SS
authors.lastname: Gidding
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tsuda
mesh_terms: D000818:Animals; D003331:Coronary Vessels / Q000473:pathology; D004280:Dobutamine / Q000494:pharmacology; D004452:Echocardiography; D006339:Heart Rate; D006352:Heart Ventricles / Q000473:pathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009200:Myocardial Contraction / Q000502:physiology*; D009203:Myocardial Infarction / Q000378:metabolism; D009206:Myocardium / Q000473:pathology; D010100:Oxygen / Q000378:metabolism; D013314:Stress, Mechanical; D020257:Ventricular Remodeling / Q000502:physiology*
chemical_list: D004280:Dobutamine; D010100:Oxygen
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