title: Effects of Epicardial and Endocardial Cardiac Resynchronization Therapy on Coronary Flow: Insights From Wave Intensity Analysis.
abstract: BACKGROUND
  The increase in global coronary flow seen with conventional biventricular pacing is mediated by an increase in the dominant backward expansion wave (BEW). Little is known about the determinants of flow in the left-sided epicardial coronary arteries beyond this or the effect of endocardial pacing stimulation on coronary physiology.
  
  
  RESULTS
  Eleven patients with a chronically implanted biventricular pacemaker underwent an acute hemodynamic and electrophysiological study. Five of 11 patients also took part in a left ventricular endocardial pacing protocol at the same time. Conventional biventricular pacing, delivered epicardially from the coronary sinus, resulted in a 9% increase in flow (average peak velocity) in the left anterior descending artery (LAD), mediated by a 13% increase in the area under the BEW (P=0.004). Endocardial pacing resulted in a 27% increase in LAD flow, mediated by a 112% increase in the area under the forward compression wave (FCW) and a 43% increase in the area under the BEW (P=0.048 and P=0.036, respectively). There were no significant changes in circumflex parameters. Conventional biventricular pacing resulted in homogenization of timing of coronary flow compared with baseline (mean difference in time to peak in the LAD versus circumflex artery: FCW 39 ms [baseline] versus 3 ms [conventional biventricular pacing], P=0.008; BEW 47 ms [baseline] versus 8 ms [conventional biventricular pacing], P=0.004).
  
  
  CONCLUSIONS
  Epicardial and endocardial pacing result in increased coronary flow in the left anterior descending artery and homogenization of the timing of waves that determine flow in the LAD and the circumflex artery. The increase in both the FCW and the BEW with endocardial pacing may be the result of a more physiological activation pattern than that of epicardial pacing, which resulted in an increase of only the BEW.
authors.affiliation: King's College, London, UK (S.C., Z.C., T.J., K.D.S., J.B., M.S., J.W., E.H., M.L., K.A., R.W., S.N.).
authors.forename: Simon
authors.initials: S
authors.lastname: Claridge
authors.affiliation: King's College, London, UK (S.C., Z.C., T.J., K.D.S., J.B., M.S., J.W., E.H., M.L., K.A., R.W., S.N.).
authors.forename: Zhong
authors.initials: Z
authors.lastname: Chen
authors.affiliation: King's College, London, UK (S.C., Z.C., T.J., K.D.S., J.B., M.S., J.W., E.H., M.L., K.A., R.W., S.N.).
authors.forename: Tom
authors.initials: T
authors.lastname: Jackson
authors.affiliation: King's College, London, UK (S.C., Z.C., T.J., K.D.S., J.B., M.S., J.W., E.H., M.L., K.A., R.W., S.N.).
authors.forename: Kalpa
authors.initials: K
authors.lastname: De Silva
authors.affiliation: King's College, London, UK (S.C., Z.C., T.J., K.D.S., J.B., M.S., J.W., E.H., M.L., K.A., R.W., S.N.).
authors.forename: Jonathan
authors.initials: J
authors.lastname: Behar
authors.affiliation: King's College, London, UK (S.C., Z.C., T.J., K.D.S., J.B., M.S., J.W., E.H., M.L., K.A., R.W., S.N.).
authors.forename: Manav
authors.initials: M
authors.lastname: Sohal
authors.affiliation: King's College, London, UK (S.C., Z.C., T.J., K.D.S., J.B., M.S., J.W., E.H., M.L., K.A., R.W., S.N.).
authors.forename: Jessica
authors.initials: J
authors.lastname: Webb
authors.affiliation: King's College, London, UK (S.C., Z.C., T.J., K.D.S., J.B., M.S., J.W., E.H., M.L., K.A., R.W., S.N.).
authors.forename: Eoin
authors.initials: E
authors.lastname: Hyde
authors.affiliation: King's College, London, UK (S.C., Z.C., T.J., K.D.S., J.B., M.S., J.W., E.H., M.L., K.A., R.W., S.N.).
authors.forename: Matthew
authors.initials: M
authors.lastname: Lumley
authors.affiliation: King's College, London, UK (S.C., Z.C., T.J., K.D.S., J.B., M.S., J.W., E.H., M.L., K.A., R.W., S.N.).
authors.forename: Kal
authors.initials: K
authors.lastname: Asrress
authors.affiliation: King's College, London, UK (S.C., Z.C., T.J., K.D.S., J.B., M.S., J.W., E.H., M.L., K.A., R.W., S.N.).
authors.forename: Rupert
authors.initials: R
authors.lastname: Williams
authors.affiliation: Guy's and St Thomas' Hospital Trust, London, UK (J.B., M.A.).
authors.forename: Julian
authors.initials: J
authors.lastname: Bostock
authors.affiliation: Guy's and St Thomas' Hospital Trust, London, UK (J.B., M.A.).
authors.forename: Motin
authors.initials: M
authors.lastname: Ali
authors.affiliation: Guy's and St Thomas' Hospital Trust and King's College, London, UK (J.G., M.N., R.R., D.P., C.A.R.).
authors.forename: Jaswinder
authors.initials: J
authors.lastname: Gill
authors.affiliation: Guy's and St Thomas' Hospital Trust and King's College, London, UK (J.G., M.N., R.R., D.P., C.A.R.).
authors.forename: Mark
authors.initials: M
authors.lastname: O'Neill
authors.affiliation: Guy's and St Thomas' Hospital Trust and King's College, London, UK (J.G., M.N., R.R., D.P., C.A.R.).
authors.forename: Reza
authors.initials: R
authors.lastname: Razavi
authors.affiliation: King's College, London, UK (S.C., Z.C., T.J., K.D.S., J.B., M.S., J.W., E.H., M.L., K.A., R.W., S.N.).
authors.forename: Steve
authors.initials: S
authors.lastname: Niederer
authors.affiliation: Guy's and St Thomas' Hospital Trust and King's College, London, UK (J.G., M.N., R.R., D.P., C.A.R.).
authors.forename: Divaka
authors.initials: D
authors.lastname: Perera
authors.affiliation: Guy's and St Thomas' Hospital Trust and King's College, London, UK (J.G., M.N., R.R., D.P., C.A.R.).
authors.forename: Christopher Aldo
authors.initials: CA
authors.lastname: Rinaldi
mesh_terms: D001783:Blood Flow Velocity; D058406:Cardiac Resynchronization Therapy / Q000379:methods; D003326:Coronary Circulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction
keywords: cardiac resynchronization therapy; coronary flow; endocardial pacing; wave intensity