title: Electromechanical effects of cardiac resynchronization therapy during rest and stress in patients with heart failure.
abstract: BACKGROUND
  Haemodynamic and functional effects of cardiac resynchronization therapy (CRT) have been studied mostly at rest. CRT effects on left ventricular (LV) dyssynchrony and function during stress have not been evaluated in detail.
  
  
  OBJECTIVE
  We studied the electromechanical effects of CRT at rest and during Dobutamine stress echocardiography (DSE), during active and withheld CRT.
  
  
  METHODS
  Twenty-one responders to CRT (62+/-12 yr) were assessed by walking test, quality of life, and BNP with active CRT ("on") and 2 weeks after pacing withdrawal ("off"). DSE (10 microg/kg/min) was performed both at "on" and "off" to evaluate dyssynchrony parameters, systolic and diastolic function.
  
  
  RESULTS
  At rest, CRT withdrawal was associated with an increased interventricular mechanical delay (IVMD, from 21+/-18 ms to 49+/-24 ms, p<0.001) and impaired intraventricular synchrony. There was a significant decrease in LV systolic function and LV filling time. Dobutamine infusion had no impact on inter- and intraventricular synchrony. During stress, there was an improvement in LV performance both at "on" and "off". However, LV dp/dt, aortic VTI, cardiac output, mean systolic peak velocities and LV filling time during dobutamine stress were significantly greater with CRT "on".
  
  
  CONCLUSIONS
  In long-term responders, CRT improves LV performance both at rest and during dobutamine stress. This is attributable to an improvement in LV synchrony, which is maintained during stress.
authors.affiliation: Institute of Cardiology of the University of Bologna, Bologna, Italy. cinzia.valzania2@studio.unibo.it <cinzia.valzania2@studio.unibo.it>
authors.forename: Cinzia
authors.initials: C
authors.lastname: Valzania
authors.forename: Fredrik
authors.initials: F
authors.lastname: Gadler
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Eriksson
authors.forename: Arne
authors.initials: A
authors.lastname: Olsson
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Boriani
authors.forename: Frieder
authors.initials: F
authors.lastname: Braunschweig
mesh_terms: D000368:Aged; D002302:Cardiac Output / Q000502:physiology; D002304:Cardiac Pacing, Artificial; D003971:Diastole / Q000502:physiology; D015150:Echocardiography, Doppler; D018619:Echocardiography, Doppler, Pulsed; D025401:Echocardiography, Stress; D005260:Female; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood; D012146:Rest / Q000502:physiology; D013318:Stroke Volume / Q000502:physiology; D013599:Systole / Q000502:physiology; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology* / Q000628:therapy; D016277:Ventricular Function, Left / Q000502:physiology
chemical_list: D020097:Natriuretic Peptide, Brain