title: Effects of cardiac resynchronization therapy on coronary blood flow: evaluation by transthoracic Doppler echocardiography.
abstract: BACKGROUND
  Relatively limited and conflicting data are available on the effects of cardiac resynchronization therapy (CRT) on coronary blood flow (CBF).
  
  
  OBJECTIVE
  To investigate changes in the left anterior descending coronary artery (LAD) flow under different CRT pacing modes by means of transthoracic Doppler echocardiography (TTE).
  
  
  METHODS
  Twenty-two responders to CRT (67+/-11 years) with idiopathic dilated cardiomyopathy underwent TTE assessment of LAD flow and Tissue Velocity Imaging during 4 programming modes: intrinsic conduction (IC), right ventricular pacing (RV), simultaneous biventricular pacing (BVP), BVP with left ventricular (LV) pre-activation.
  
  
  RESULTS
  Mean coronary flow velocity (CFV) was increased by simultaneous BVP (p=0.0063 vs. IC) and BVP with LV pre-activation (p<0.0001 vs. IC; p=0.027 vs. simultaneous BVP). Peak CFV and LAD flow velocity/time integral were highest during BVP with LV pre-activation. A reduction in septal-to-lateral delay and an increase in peak systolic velocity in the basal septum were observed during simultaneous BVP and BVP with LV pre-activation.
  
  
  CONCLUSIONS
  In CRT responders with idiopathic dilated cardiomyopathy, an increase in LAD flow, assessed by TTE, was observed during simultaneous BVP and BVP with LV pre-activation. This was associated with an improvement in regional myocardial contraction and a decrease in intraventricular dyssynchrony.
authors.affiliation: Department of Medicine, Division of Cardiology, Karolinska Institutet, Stockholm, Sweden. 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: Reidar
authors.initials: R
authors.lastname: Winter
authors.forename: Frieder
authors.initials: F
authors.lastname: Braunschweig
authors.forename: Lars-Ake
authors.initials: LA
authors.lastname: Brodin
authors.forename: Petri
authors.initials: P
authors.lastname: Gudmundsson
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Boriani
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Eriksson
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D002304:Cardiac Pacing, Artificial; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000628:therapy*; D003326:Coronary Circulation; D004452:Echocardiography; D015150:Echocardiography, Doppler; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D018487:Ventricular Dysfunction, Left / Q000209:etiology / Q000628:therapy*