The top left panel shows normal ventricular activation (blue arrow).
Note left to right septal activation, then superiorly to septal border
of the crista supraventricularis (CSV) and meets the RV free wall
wavefront exiting from right bundle branch
The left lower panels show a possible pathway of the of the parallel
wavefront (yellow arrow) which, after it reaches the septum moves
superiorly to CSV towards the RV free wall. This early rightward
activation may result in counterclockwise rotation of the QRS complex.
The right upper panel shows that in RBBB, the parallel wavefront after
reaching the CSV and finding an unexcited RV free wall it continues
rightward and decreases the duration of S wave. At higher voltage the
parallel wavefront may pre-excite larger portion of RV free wall than at
lower voltage with slower conduction. The degree of fusion would
determine the duration of S wave while the block remains unresolved.
Right lower panel shows an alternative mechanism where the parallel
pathway connects to the His Purkinje system distal to site of block. At
higher voltage the parallel wavefront would arrive at this site earlier
and no RBBB is seen, and at lower voltage the slower conduction in
parallel wavefront allows conduction to occur via His bundle with
manifest RBBB.
.
Limitations
There are many difficulties in trying to explain phenomenon observed
following active fixation of pacing lead with electrophysiologic
principles obtained using atraumatic diagnostic catheters. The mechanism
will remain a hypothesis until further studies increase our
understanding of the complex area surrounding the His bundle.
No high-density mapping data was obtained to determine the exact pathway
of the pre-excitation wavefront and we relied mainly on analysis of
surface ECG.
Clinical Significance
Non-selective His bundle pacing may, in essence, be activating an
additional pathway with behavior suggestive of a ‘parallel His bundle’
(25). In patients with His bundle disease, NS-HBP may deserve
consideration as preferred mode of His bundle pacing.
Our study also suggests that the paradigm of lowering pacing voltage to
prolong battery life may not apply to His bundle pacing as correction of
conduction block often occurs at higher voltage pacing.
References
- Narula OS. Longitudinal dissociation in the His bundle. Bundle branch
block due to asynchronous conduction within the His bundle in man.Circulation. 1977;56(6):996-1006.
- El-Sherif N, Amay YLF, 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(3):473- 483.
- Vijayaraman P, Dandamudi G, Zanon F, et al. Permanent His bundle
pacing: Recommendations from a Multicenter His Bundle Pacing
Collaborative Working Group for standardization of definitions,
implant measurements, and follow-up. Heart Rhythm. 2018;15(3):460-468.
- Sharma PS, Naperkowski A, Bauch TD, et al. Permanent His Bundle Pacing
for Cardiac Resynchronization Therapy in Patients with Heart Failure
and Right Bundle Branch Block. Circ Arrhythm Electrophysiol.
2018;11(9).
- Mahmud R, Jamal S, Musheinesh M. Voltage dependent conduction
abnormalities in His bundle pacing in patients without His Purkinje
system disease. J Electrocardiol. 2019;59:1-6
- Kupersmith J, Krongrad E, Waldo AL, Conduction Intervals and
Conduction Velocity in the Human Cardiac Conduction System. 1973
Circulation;47(4):776- 785
- Joyner RW. Mechanisms of unidirectional block in cardiac tissues.
Biophysical Journal.
- Boineau JP, Spach MS. The relationship between the electrocardiogram
and the electrical activity of the heart. Journal of
Electrocardiology. 1968;1(1):117- 124.
- Dodge FA, Cranefield PF Normal and abnormal conduction in the heart.
Nonuniform conduction in cardiac Purkinje fibers. Futura Publishing
Company Inc, Mount Kisco New York 1998. 379p.
- Myerburg RJ. Nilsson K, Befelev B, Castellanos A, Gelband H.
Transverse spread and longitudinal dissociation in distal A-V
conducting system. J Clin Invest 1977;52: 885-895
- Roth B.J., ”A mathematical model of make and break electrical
stimulation of cardiac tissue by a unipolar anode or cathode,”
in IEEE Transactions on Biomedical Engineering , vol. 42, no.
12, pp. 1174-1184, Dec. 1995, doi: 10.1109/10.476124.
- Sambelashvili AT, Nikolski VP, and Efimov IR Am J Physiol Heart
Circ Physiol 286: H2183–H2194, 2004.
- Hucker WJ, McCain ML, Laughner JI, Iaizzo PA, Efimov IR. Connexin 43
expression delineates two discrete pathways in the human
atrioventricular junction. Anat Rec (Hoboken). 2008;291(2):204-215.
- George SA, Faye NR, Murillo-Berlioz A, Lee KB, Trachiotis GD, Efimov
IR. At the Atrioventricular Crossroads: Dual Pathway Electrophysiology
in the Atrioventricular Node and its Underlying Heterogeneities.
Arrhythm Electrophysiol Rev. 2017;6(4):179-185.
- Jamal S, Bailey B, Mahmud R. Comparison of Ventricular Activation Time
in Sinus and His Bundle Paced Beats. Circulation Nov 2020 Abstr.
- Durrer D, van Dam RT, Freud GE, Janse MJ, Meijler FL, Arzbaecher RC.
Total excitation of the isolated human heart. Circulation.
1970;41(6):899-912.
- De Almeida MC, Araujo M, Duque M, Vilhena V. Crista Supraventricularis
Purkinje Network and its Relation to Intraseptal Purkinje Network.
Anat Rec (Hoboken). 2017;300(10):1793-1801.
- De Almeida MC, Stephenson RS, Anderson RH, Benvenuti LA, Loukas M,
Aiello VD. Human subpulmonary infundibulum has an endocardial network
of specialized conducting cardiomyocytes. Heart Rhythm.
2020;17(1):123-130
- Amer NS, Stuckey JH, Hoffman BF, Cappelletti RR, Domingo RT.
Activation of the interventricular septal myocardium studied during
cardiopulmonary bypass. Am Heart J. 1960;59:224-237.
- James TN. Anatomy of the crista supraventricularis: its importance for
understanding right ventricular function, right ventricular infarction
and related conditions. J Am Coll Cardiol. 1985;6(5):1083-1095.
- Kaufman R, Rothberger CJ: Beitrage zur entstehungsweise extra-
sysolischer allorhythmien (Zweite Mitteilung). Z Gesamte Exp Med 7:
199, 1919
- Sciacca A, Sangiorgi M: Trouble de la conduction intraventriculaire
droite duala lesion dutronc commun dufaiseaude His. ActaCardiol 2:
486, 1957
- Lazzara R, Yeh BK, Samet P: Functional transverse interconnections
within the His bundle and the bundle branches. Circ Res 32: 509, 1973
9.
- Bailey JC, Spear JF, Moore EN: Functional significance of transverse
conducting pathways within the canine bundle of His. Am J Cardiol 34:
790, 1974
- Personal communication with Dr. Igor Effimov
- Vassallo, J. A., Cassidy, D. M., Miller, J. M., Buxton, A.
E., Marchlinski, F. E., & Josephson, M. E. (1986). Left ventricular
endocardial activation during right ventricular pacing: Effect of
underlying heart disease. Journal of the American College of
Cardiology,7 (6), 1228-1233. doi:10.1016/s0735-1097(86)80140-1
- Williams DO, Scherlag BJ, Hope RR, El-Sherif N, Lazzara R, Samet P.
Selective versus non-selective His bundle pacing. Cardiovascular
Research1976;10(1):91-100. doi:10.1093/cvr/10.1.91