Anatomy, pathophysiology and localization of accessory pathways in the preexcitation syndrome
- Bradley P Knight, MD, FACC
Bradley P Knight, MD, FACC
- Section Editor — Cardiac Arrhythmias
- Professor of Medicine
- Feinberg School of Medicine, Northwestern University
Conduction from the atria to the ventricles normally occurs via the atrioventricular node (AV)-His-Purkinje system. Patients with a preexcitation syndrome have an additional or alternative pathway, known as an accessory pathway, which directly connects the atria and ventricle and bypasses the AV node. AV conduction through an accessory pathway (most commonly a direct AV connection) results in the earlier activation of the ventricles than if the impulse had traveled through the AV node; hence the term preexcitation.
Accessory pathway is a generic term which may indicate either a "tract" which bypasses the AV node but inserts into the specialized conduction system (eg, the bundle of His, right or left bundles, or one of the fascicles), or a "connection" which bypasses the AV node and terminates directly within the myocardium. Other names that may be used include anomalous AV pathway, connection, or tract; accessory AV bypass pathway, connection, or tract; or simply AV bypass, tract, or pathway. (See "General principles of asynchronous activation and preexcitation".)
At other times, the specific sites of origin and termination are used. Examples include accessory atrioventricular connection, atrio-Hisian pathway or connection, or atriofascicular pathway or connection (table 1).
Preexcitation through an AV bypass tract, the bundle of Kent, produces the electrocardiographic pattern described by Wolff, Parkinson, and White in 1930 . The terms preexcitation and Wolff-Parkinson-White (WPW) syndrome are often used interchangeably even though there are other forms of preexcitation. The electrocardiographic pattern of WPW should be differentiated from the "WPW syndrome," since patients with the latter have both the electrocardiographic pattern of preexcitation and paroxysmal tachyarrhythmias . (See "Epidemiology, clinical manifestations, and diagnosis of the Wolff-Parkinson-White syndrome".)
This topic will review the anatomy and electrophysiologic properties of the accessory pathways. The related issue of asynchronous activation, the arrhythmias associated with WPW, and the pharmacologic and nonpharmacologic treatments of patients with this syndrome are discussed separately. (See appropriate topic reviews). A detailed discussion of electrophysiologic mapping techniques is found elsewhere. (See "Invasive cardiac electrophysiology studies", section on 'Mapping and ablation'.)
- Wolff L, Parkinson J, White PD. Bundle branch block with a short P-R interval in healthy young people prone to paroxysmal tachycardia. Am Heart J 1930; 5:685.
- Definition of terms related to cardiac rhythm. Am Heart J 1978; 95:796.
- Waller BF. Clinicopathological correlations of the human cardiac conduction system. In: Cardiac Electrophysiology, Zipes DP, Jalife J (Eds), WB Saunders, Philadelphia 1990. p.249.
- Anderson RH, Becker AE, Brechenmacher C, et al. Ventricular preexcitation. A proposed nomenclature for its substrates. Eur J Cardiol 1975; 3:27.
- Ferguson TB, Cox JL. Surgical treatment for the Wolff-Parkinson-White syndrome: the endocardial approach. In: Cardiac Electrophysiology, Zipes DP, Jalife J (Eds), WB Saunders, Philadelphia 1990. p.897.
- Cox JL, Gallagher JJ, Cain ME. Experience with 118 consecutive patients undergoing operation for the Wolff-Parkinson-White syndrome. J Thorac Cardiovasc Surg 1985; 90:490.
- Cain ME, Cox JL. Surgical treatment of supraventricular arrhythmias. In: Management of cardiac arrhythmias: the nonpharmacologic approach, Platia E (Ed), JB Lippincott, Philadelphia 1987. p.304.
- Gallagher JJ, Sealy WC, Kasell J. Intraoperative mapping studies in the Wolff-Parkinson-White syndrome. Pacing Clin Electrophysiol 1979; 2:523.
- Gallagher JJ, Pritchett EL, Sealy WC, et al. The preexcitation syndromes. Prog Cardiovasc Dis 1978; 20:285.
- Reddy GV, Schamroth L. The localization of bypass tracts in the Wolff-Parkinson-White syndrome from the surface electrocardiogram. Am Heart J 1987; 113:984.
- Fananapazir L, German LD, Gallagher JJ, et al. Importance of preexcited QRS morphology during induced atrial fibrillation to the diagnosis and localization of multiple accessory pathways. Circulation 1990; 81:578.
- Lindsay BD, Crossen KJ, Cain ME. Concordance of distinguishing electrocardiographic features during sinus rhythm with the location of accessory pathways in the Wolff-Parkinson-White syndrome. Am J Cardiol 1987; 59:1093.
- Milstein S, Sharma AD, Guiraudon GM, Klein GJ. An algorithm for the electrocardiographic localization of accessory pathways in the Wolff-Parkinson-White syndrome. Pacing Clin Electrophysiol 1987; 10:555.
- Cain ME, Luke RA, Lindsay BD. Diagnosis and localization of accessory pathways. Pacing Clin Electrophysiol 1992; 15:801.
- Otomo K, Gonzalez MD, Beckman KJ, et al. Reversing the direction of paced ventricular and atrial wavefronts reveals an oblique course in accessory AV pathways and improves localization for catheter ablation. Circulation 2001; 104:550.
- MacRae CA, Ghaisas N, Kass S, et al. Familial Hypertrophic cardiomyopathy with Wolff-Parkinson-White syndrome maps to a locus on chromosome 7q3. J Clin Invest 1995; 96:1216.
- Chauvin M, Shah DC, Haïssaguerre M, et al. The anatomic basis of connections between the coronary sinus musculature and the left atrium in humans. Circulation 2000; 101:647.
- Sun Y, Arruda M, Otomo K, et al. Coronary sinus-ventricular accessory connections producing posteroseptal and left posterior accessory pathways: incidence and electrophysiological identification. Circulation 2002; 106:1362.
- Prystowsky EN, Page RL. Electrophysiology and autonomic influences of the human atrioventricular node. In: Electrophysiology of the Sinoatrial and Atrioventricular Nodes, Mazgalev T, Dreifus L, Michelson EL (Eds).
- Sternick EB, Timmermans C, Sosa E, et al. The electrocardiogram during sinus rhythm and tachycardia in patients with Mahaim fibers: the importance of an "rS" pattern in lead III. J Am Coll Cardiol 2004; 44:1626.
- Gaita F, Haissaguerre M, Giustetto C, et al. Catheter ablation of permanent junctional reciprocating tachycardia with radiofrequency current. J Am Coll Cardiol 1995; 25:648.
- de Chillou C, Rodriguez LM, Schläpfer J, et al. Clinical characteristics and electrophysiologic properties of atrioventricular accessory pathways: importance of the accessory pathway location. J Am Coll Cardiol 1992; 20:666.
- Bogun F, Kalusche D, Li YG, et al. Septal Q waves in surface electrocardiographic lead V6 exclude minimal ventricular preexcitation. Am J Cardiol 1999; 84:101.
- Yoshida T, Ikeda H, Hiraki T, et al. Detection of concealed left sided accessory atrioventricular pathway by P wave signal averaged electrocardiogram. J Am Coll Cardiol 1999; 33:55.
- Josephson ME. Preexcitation Syndromes. In: Clinical Cardiac Electrophysiology, Lea & Febiger, Philadelphia 1993. p.311.
- German LD, Gallagher JJ. Functional properties of accessory atrioventricular pathways in Wolff-Parkinson-White syndrome. Clinical implications. Am J Med 1984; 76:1079.
- Nalos PC, Deng Z, Gang ES, et al. Intermittent preexcitation: Clinical recognition and management. Pract Cardiol 1985; 11:49.
- Chen SA, Tai CT, Chiang CE, et al. Electrophysiologic characteristics, electropharmacologic responses and radiofrequency ablation in patients with decremental accessory pathway. J Am Coll Cardiol 1996; 28:732.
- Murdock CJ, Leitch JW, Teo WS, et al. Characteristics of accessory pathways exhibiting decremental conduction. Am J Cardiol 1991; 67:506.
- Tchou P, Lehmann MH, Jazayeri M, Akhtar M. Atriofascicular connection or a nodoventricular Mahaim fiber? Electrophysiologic elucidation of the pathway and associated reentrant circuit. Circulation 1988; 77:837.
- Gillette PC, Garson A Jr, Cooley DA, McNamara DG. Prolonged and decremental antegrade conduction properties in right anterior accessory connections: Wide QRS antidromic tachycardia of left bundle branch block pattern without Wolff-Parkinson-White configuration in sinus rhythm. Am Heart J 1982; 103:66.
- Ross DL, Uther JB. Diagnosis of concealed accessory pathways in supraventricular tachycardia. Pacing Clin Electrophysiol 1984; 7:1069.
- Gillette PC. Concealed anomalous cardiac conduction pathways: a frequent cause of supraventricular tachycardia. Am J Cardiol 1977; 40:848.
- Meiltz A, Weber R, Halimi F, et al. Permanent form of junctional reciprocating tachycardia in adults: peculiar features and results of radiofrequency catheter ablation. Europace 2006; 8:21.
- Fitzpatrick AP, Gonzales RP, Lesh MD, et al. New algorithm for the localization of accessory atrioventricular connections using a baseline electrocardiogram. J Am Coll Cardiol 1994; 23:107.
- Gallagher JJ, Sealy WC, Kasell J, Wallace AG. Multiple accessory pathways in patients with the pre-excitation syndrome. Circulation 1976; 54:571.
- Arruda M, Wang X, McClennand J, et al. ECG algorithm for predicting sites of successful radiofrequency ablation of accessory pathways (abstract). Pacing Clin Electrophysiol 1993; 16(Pt 2):865.
- Epstein AE, Kirklin JK, Holman WL, et al. Intermediate septal accessory pathways: electrocardiographic characteristics, electrophysiologic observations and their surgical implications. J Am Coll Cardiol 1991; 17:1570.
- Arruda MS, McClelland JH, Wang X, et al. Development and validation of an ECG algorithm for identifying accessory pathway ablation site in Wolff-Parkinson-White syndrome. J Cardiovasc Electrophysiol 1998; 9:2.
- Moss JD, Gerstenfeld EP, Deo R, et al. ECG criteria for accurate localization of left anterolateral and posterolateral accessory pathways. Pacing Clin Electrophysiol 2012; 35:1444.
- Sternick EB, Sosa EA, Timmermans C, et al. Automaticity in Mahaim fibers. J Cardiovasc Electrophysiol 2004; 15:738.
- Sternick EB, Gerken LM. The 12-lead ECG in patients with Mahaim fibers. Ann Noninvasive Electrocardiol 2006; 11:63.
- ANATOMIC CONSIDERATIONS
- Transverse plane
- Longitudinal plane
- Associated structural cardiac abnormalities
- ELECTROPHYSIOLOGY OF PREEXCITATION
- Ventricular activation
- - Minimal preexcitation in WPW
- PR interval
- Intermittent preexcitation
- Preexcitation alternans
- Concertina effect
- Accessory pathways exhibiting decremental conduction
- Concealed accessory pathways
- RELATIONSHIP BETWEEN ACCESSORY PATHWAY SITE AND THE ELECTROCARDIOGRAPHIC PATTERN
- Localizing the accessory AV connection site based upon the ECG
- Vector of the delta wave