title: Enhanced inotropic state of the failing left ventricle by cardiac contractility modulation electrical signals is not associated with increased myocardial oxygen consumption.
abstract: BACKGROUND
  Previous studies in patients and in dogs with experimentally induced heart failure (HF) showed that electrical signals applied to the failing myocardium during the absolute refractory period improved left ventricular (LV) function. We examined the effects these same cardiac contractility modulating (CCM) electrical signals on myocardial oxygen consumption (MVO(2)) in both patients and dogs with chronic HF.
  
  
  RESULTS
  Six dogs with microembolizations-induced HF and 9 HF patients underwent CCM leads and generator (OPTIMIZER II) implantation. After baseline measurements, CCM signals were delivered continuously for 2 hours in dogs and for 30 minutes in patients. MVO(2) was measured before and after CCM therapy. In dogs, CCM therapy increased LV ejection fraction at 2 hours (26 +/- 1 versus 31 +/- 2 %, P = .001) without increasing MVO(2) (257 +/- 41 versus 180 +/- 34 micromol/min). In patients, CCM therapy increased LV peak +dP/dt by 10.1 +/- 1.5 %. As with dogs, the increase in LV function after 30 minutes of CCM therapy was not associated with increased MVO(2) (13.6 +/- 9.7 versus 12.5 +/- 7.2 mL O(2)/min).
  
  
  CONCLUSIONS
  The study results suggest that unlike cAMP-dependent positive inotropic drugs, the increase in LV function during CCM therapy is elicited without increasing MVO(2).
authors: From the German Heart Institute Berlin, Berlin, Germany.
authors: Christian
authors: C
authors: Butter
authors: Ernst
authors: E
authors: Wellnhofer
authors: Michael
authors: M
authors: Schlegl
authors: Georgia
authors: G
authors: Winbeck
authors: Eckart
authors: E
authors: Fleck
authors: Hani N
authors: HN
authors: Sabbah
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D002316:Cardiotonic Agents / Q000627:therapeutic use*; D004195:Disease Models, Animal; D004285:Dogs; D004554:Electric Countershock / Q000379:methods*; D004562:Electrocardiography; D005500:Follow-Up Studies; D006333:Heart Failure / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology*; D013318:Stroke Volume / Q000187:drug effects / Q000502:physiology; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000187:drug effects / Q000502:physiology*
chemical_list: D002316:Cardiotonic Agents