Stimulation and propagation of activation in conduction tissue: Implications for left bundle branch area pacing

Published:January 05, 2021DOI:


      Characterizing wavefront generation and impulse conduction in left bundle (LB) has implications for left bundle branch area pacing (LBBAP).


      The purpose of this study was to describe the pacing characteristics of LB and to study the role of pacing pulse width (PW) in overcoming left bundle branch block.


      Twenty fresh ovine heart slabs containing well-developed and easily identifiable tissues of the conduction system were used for the study. LB stimulation, activation, and propagation were studied under baseline conditions, simulated conduction slowing, conduction block, and fascicular block.


      The maximum radius of the LB early activation increased up to 13.4 ± 2.4 mm from the pacing stimulus, and the time from stimulus to evoked potential shortened when pacing PW was increased from 0.13 to 2 ms at baseline. Conduction slowing and block induced by cooling could be resolved by increasing pacing PW from 0.25 to 1.5 ms over a distance of 10 ± 1.5 mm from the pacing stimulus. The LB strength-duration (SD) curve was shifted to the left of the myocardial SD curve.


      Increasing PW resolved conduction slowing and block and bypassed the experimental model of fascicular block in LB. Precise positioning of the LB lead in left ventricular subendocardium is not mandatory in LBBAP, as the SD curve of LB was shifted to the left of the myocardium SD curve and could be captured from a distance by optimizing PW.

      Graphical abstract


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        • Lustgarten D.L.
        • Calame S.
        • Crespo E.M.
        • Calame J.
        • Lobel R.
        • Spector P.S.
        Electrical resynchronization induced by direct His-bundle pacing.
        Heart Rhythm. 2010; 7: 15-21
        • Abraham W.T.
        • Fisher W.G.
        • Smith A.L.
        • et al.
        Cardiac resynchronization in chronic heart failure.
        N Engl J Med. 2002; 346: 1845-1853
        • Leclercq C.
        • Kass D.A.
        Retiming the failing heart: principles and current clinical status of cardiac resynchronization.
        J Am Coll Cardiol. 2002; 39: 194-201
        • Young J.B.
        • Abraham W.T.
        • Smith A.L.
        • et al.
        Combined cardiac resynchronization and implantable cardioversion defibrillation in advanced chronic heart failure: the MIRACLE ICD Trial.
        J Am Med Assoc. 2003; 289: 2685-2694
        • Abdelrahman M.
        • Subzposh F.A.
        • Beer D.
        • et al.
        Clinical outcomes of His bundle pacing compared to right ventricular pacing.
        J Am Coll Cardiol. 2018; 71: 2319-2330
        • Bhatt A.G.
        • Musat D.L.
        • Milstein N.
        • et al.
        The efficacy of His bundle pacing: lessons learned from implementation for the first time at an experienced electrophysiology center.
        J Am Coll Cardiol. 2018; 4: 1397-1406
        • Zhang S.
        • Zhou X.
        • Gold M.R.
        Left bundle branch pacing: JACC review topic of the week.
        J Am Coll Cardiol. 2019; 74: 3039-3049
        • Huang W.
        • Su L.
        • Wu S.
        • et al.
        A novel pacing strategy with low and stable output: pacing the left bundle branch immediately beyond the conduction block.
        Can J Cardiol. 2017; 33: P1736.E1-P1736.E3
        • Vassallo J.A.
        • Cassidy D.M.
        • Marchlinski F.E.
        • et al.
        Endocardial activation of left bundle branch block.
        Circulation. 1984; 69: 914-923
        • Upadhyay G.A.
        • Cherian T.
        • Shatz D.Y.
        • et al.
        Intracardiac delineation of septal conduction in left bundle-branch block patterns.
        Circulation. 2019; 139: 1876-1888
        • Condorelli L.
        Schenkelblock durch Laesion des Tawaraknotens.
        Sonderabdruck aus den Verhandlungen der Dtsch Gesellschaft fur Kreislauforsch, 1932
        • Sciacca A.
        • Sangiorgi M.
        Trouble de la conduction intraventriculaire droite du a la lesion du tronc common du faiseau de His.
        Acta Cardiol. 1957; 2: 486
        • El-Sherif N.
        • Amay-Y-Leon F.
        • Schonfield C.
        • et al.
        Normalization of bundle branch block patterns by distal His bundle pacing. Clinical and experimental evidence of longitudinal dissociation in the pathologic his bundle.
        Circulation. 1978; 57: 473-483
        • Cheng Y.
        • Mowrey K.A.
        • Wagoner D.R.V.
        • Tchou P.J.
        • Efimov I.R.
        Virtual electrode–induced reexcitation.
        Circ Res. 1999; 85: 1056-1066
        • Sambelashvili A.T.
        • Nikolski V.P.
        • Efimov I.R.
        Virtual electrode theory explains pacing threshold increase caused by cardiac tissue damage.
        Am J Physiol Heart Circ Physiol. 2004; 286: H2183-H2194
        • Teng A.E.
        • Massoud L.
        • Ajijola O.A.
        Physiological mechanisms of QRS narrowing in bundle branch block patients undergoing permanent His bundle pacing.
        J Electrocardiol. 2016; 49: 644-648
        • Jastrzębski M.
        • Moskal P.
        • Bednarek A.
        • Kiełbasa G.
        • Vijayaraman P.
        • Czarnecka D.
        His bundle has a shorter chronaxie than does the adjacent ventricular myocardium: implications for pacemaker programming.
        Heart Rhythm. 2019; 16: 1808-1816
        • Irnich W.
        The chronaxie time and its practical importance.
        Pacing Clin Electrophysiol. 1980; 3: 292-301
        • Geddes L.A.
        Accuracy limitations of chronaxie values.
        IEEE Trans Biomed Eng. 2004; 51: 176-181
        • Huang W.
        • Chen X.
        • Su L.
        • Wu S.
        • Xia X.
        • Vijayaraman P.
        A beginner’s guide to permanent left bundle branch pacing.
        Heart Rhythm. 2019; 16: 1791-1796
        • Beer D.
        • Sharma P.S.
        • Subzposh F.A.
        • et al.
        Clinical outcomes of selective versus nonselective His bundle pacing.
        JACC Clin Electrophysiol. 2019; 5: 766-774
        • Fisher J.D.
        Hemiblocks and the fascicular system: myths and implications.
        J Interv Card Electrophysiol. 2018; 52: 281-285
        • Wald R.W.
        • Waxman M.B.
        • Downar E.
        The effect of antiarrhythmic drugs on depressed conduction and unidirectional block in ovine Purkinje fibers.
        Circ Res. 1980; 46: 612-619
        • Pressler M.L.
        Cable analysis in quiescent and active sheep Purkinje fibres.
        J Physiol. 1984; 353: 739-757
        • Fozzard H.A.
        • Schoenberg M.
        Strength-duration curves in cardiac Purkinje fibres: effects of liminal length and charge distribution.
        J Physiol. 1972; 226: 593-618