title: Simultaneous His Bundle and Left Ventricular Pacing for Optimal Cardiac Resynchronization Therapy Delivery: Acute Hemodynamic Assessment by Pressure-Volume Loops.
abstract: BACKGROUND
  Previous studies have investigated the role of intrinsic conduction in optimizing cardiac resynchronization therapy. We investigated the role of fusing pacing-induced activation and intrinsic conduction in cardiac resynchronization therapy by evaluating the acute hemodynamic effects of simultaneous His-bundle (HIS) and left ventricular (LV) pacing.
  
  
  RESULTS
  We studied 11 patients with systolic heart failure and left bundle-branch block scheduled for cardiac resynchronization therapy implantation. On implantation, LV pressure-volume data were determined via conductance catheter. Standard leads were placed in the right atrium, at the right ventricular apex, and in a coronary vein. An additional electrode was temporarily positioned in the HIS. The following pacing configurations were systematically assessed: standard biventricular (right ventricular apex+LV), LV-only, HIS, simultaneous HIS and LV (HIS+LV). Each configuration was compared with the AAI mode at multiple atrioventricular delays (AVD). In comparison with the AAI, right ventricular apex+LV and LV-only pacing resulted in improved stroke volume (85±32 mL and 86±33 mL versus 58±23 mL; P<0.001), stroke work, maximum pressure derivative, and systolic dyssynchrony at individually optimized AVD. The optimal AVD was close to the P-H interval in the majority of patients. By contrast, HIS-LV pacing improved hemodynamic indexes at all AVD (stroke volume >76 mL at all fixed intervals and 88±31 mL at optimal interval; all P<0.001).
  
  
  CONCLUSIONS
  Standard right ventricular apex+LV and LV-only pacing enhanced systolic function and LV synchrony at individually optimized AVD close to the measured intrinsic P-H interval. By contrast, HIS+LV pacing yielded improvements, regardless of AVD setting. These findings support the hypothesis of the crucial role of intrinsic right ventricular conduction in optimal cardiac resynchronization therapy delivery.
authors.affiliation: From the Heart and Vessels Department, University of Florence, Florence (L.P., P.P., G.R., L.I., L.C., A.M.); Cardiovascular Department, IRCCS MultiMedica, Sesto San Giovanni (Milan) (L.P.); Department of Cardiovascular Diseases, University of Siena, Siena (M.P.); and CRM Department, Boston Scientific Italia, Milan, Italy (F.P., S.V.). lpadeletti@interfree.it.
authors.forename: Luigi
authors.initials: L
authors.lastname: Padeletti
authors.affiliation: From the Heart and Vessels Department, University of Florence, Florence (L.P., P.P., G.R., L.I., L.C., A.M.); Cardiovascular Department, IRCCS MultiMedica, Sesto San Giovanni (Milan) (L.P.); Department of Cardiovascular Diseases, University of Siena, Siena (M.P.); and CRM Department, Boston Scientific Italia, Milan, Italy (F.P., S.V.).
authors.forename: Paolo
authors.initials: P
authors.lastname: Pieragnoli
authors.affiliation: From the Heart and Vessels Department, University of Florence, Florence (L.P., P.P., G.R., L.I., L.C., A.M.); Cardiovascular Department, IRCCS MultiMedica, Sesto San Giovanni (Milan) (L.P.); Department of Cardiovascular Diseases, University of Siena, Siena (M.P.); and CRM Department, Boston Scientific Italia, Milan, Italy (F.P., S.V.).
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ricciardi
authors.affiliation: From the Heart and Vessels Department, University of Florence, Florence (L.P., P.P., G.R., L.I., L.C., A.M.); Cardiovascular Department, IRCCS MultiMedica, Sesto San Giovanni (Milan) (L.P.); Department of Cardiovascular Diseases, University of Siena, Siena (M.P.); and CRM Department, Boston Scientific Italia, Milan, Italy (F.P., S.V.).
authors.forename: Lisa
authors.initials: L
authors.lastname: Innocenti
authors.affiliation: From the Heart and Vessels Department, University of Florence, Florence (L.P., P.P., G.R., L.I., L.C., A.M.); Cardiovascular Department, IRCCS MultiMedica, Sesto San Giovanni (Milan) (L.P.); Department of Cardiovascular Diseases, University of Siena, Siena (M.P.); and CRM Department, Boston Scientific Italia, Milan, Italy (F.P., S.V.).
authors.forename: Luca
authors.initials: L
authors.lastname: Checchi
authors.affiliation: From the Heart and Vessels Department, University of Florence, Florence (L.P., P.P., G.R., L.I., L.C., A.M.); Cardiovascular Department, IRCCS MultiMedica, Sesto San Giovanni (Milan) (L.P.); Department of Cardiovascular Diseases, University of Siena, Siena (M.P.); and CRM Department, Boston Scientific Italia, Milan, Italy (F.P., S.V.).
authors.forename: Margherita
authors.initials: M
authors.lastname: Padeletti
authors.affiliation: From the Heart and Vessels Department, University of Florence, Florence (L.P., P.P., G.R., L.I., L.C., A.M.); Cardiovascular Department, IRCCS MultiMedica, Sesto San Giovanni (Milan) (L.P.); Department of Cardiovascular Diseases, University of Siena, Siena (M.P.); and CRM Department, Boston Scientific Italia, Milan, Italy (F.P., S.V.).
authors.forename: Antonio
authors.initials: A
authors.lastname: Michelucci
authors.affiliation: From the Heart and Vessels Department, University of Florence, Florence (L.P., P.P., G.R., L.I., L.C., A.M.); Cardiovascular Department, IRCCS MultiMedica, Sesto San Giovanni (Milan) (L.P.); Department of Cardiovascular Diseases, University of Siena, Siena (M.P.); and CRM Department, Boston Scientific Italia, Milan, Italy (F.P., S.V.).
authors.forename: Francesco
authors.initials: F
authors.lastname: Picariello
authors.affiliation: From the Heart and Vessels Department, University of Florence, Florence (L.P., P.P., G.R., L.I., L.C., A.M.); Cardiovascular Department, IRCCS MultiMedica, Sesto San Giovanni (Milan) (L.P.); Department of Cardiovascular Diseases, University of Siena, Siena (M.P.); and CRM Department, Boston Scientific Italia, Milan, Italy (F.P., S.V.).
authors.forename: Sergio
authors.initials: S
authors.lastname: Valsecchi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002036:Bundle of His / Q000503:physiopathology*; D002037:Bundle-Branch Block / Q000503:physiopathology / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D016896:Treatment Outcome; D017725:Ventricular Pressure
keywords: CRT; His bundle; fusion; heart failure; pressure volume loop; resynchronization