- Email: [email protected]
The syndrome of normal electrocardiograms, accessory pathways and paroxysmal tachycardias
J. ELECTROCARDIOLOGY, 10 (2) 1977, 157-164
The Syndrome of Normal Electrocardiograms, Accessory Pathways and Paroxysmal Tachycardias BY LAWRENCE GOULD, M.D., C. V. RAMANA REDDY, M.D., W. CHUA, M.D., C. SWAMY, M.D. AND J. C. DORISMOND, M.D.
SUMMARY
the retrograde direction only. Antegrade conduction is via the AV node and therefore the ECG does not reveal any characteristic abnormalities. 4 Recently we described a patient with recurrent tachycardias, no electrocardiographic evidence of pre-excitation and ant e g r a d e conduction t h a t bypassed t h e AV node. ~ Over the past year we have recognized six additional patients with the identical condition. This paper will describe the clinical and conduction studies in this new entity.
Tachycardias may be associated with the pre-excitation syndrome, a short PR interval or a prolonged QT interval. This report describes seven patients whose electrocardiograms (ECGs) did not reveal any of the above-named conditions. All of the patients presented with syncopal episodes, and the history of palpitations was elicited in five of the patients. His bundle electrogram studies in all of the patients showed an essentially unchanged AH interval with atrial pacing rates up to 180 beats/rain. This can only be explained by a total bypass of the AV node. Two of the patients were also paced from the ventricle, and an unchanged pacing stimulus to A wave interval was observed. This signifies in these patients a functioning bypass pathway in the retrograde direction as well. Thus it would appear that pre-excitation cannot be eliminated as a diagnostic possibility even if the ECG is normal.
CASE REPORTS Case 1. This 78 year old female was admitted to the hospital on 11/16/74 after fainting in her physician's office. The patient became aware of palpitations at the age of nine. These episodes occurred once a month and continued throughout the years. On frequent occasions the palpitations were followed by syncopal episodes. Four months prior to admission, she developed an episode of severe chest pain, and an inferior wall myocardial infarction was diagnosed. She subsequently made an uneventful recovery. On the day of examination she had visited her physician for a check-up examination. An examination revealed no detectable blood pressure and a rapid cardiac rate. She t h e n s p o n t a n e o u s l y r e v e r t e d to sinus r h y t h m with recovery of consciousness. She was immediately transferred to the hospital for admission. On examination, her blood pressure was 130/80 m m H g and the pulse rate was 80 beats/min. The neck veins were not prominent and the lungs were clear. There were no m u r m u r s or gallops. The liver was not palpable a n d t h e r e was no peripheral edema. An ECG revealed a PR interval of 0.17 sec and a QRS duration of 0.08 sec (Fig. 1). A delta wave was not present. There was evidence of the old inferior wall myocardial infarction. In order to evaluate the conduction system, a His bundle electrogram was obtained with right atrial pacing. The results are listed in Table I. With atrial pacing rates of 110 to 180 beats/rain, the AH and HV intervals remained essentially unchanged. At the conclusion of the study the patient spontaneously developed atrial fibrillation with a ventricular response of approximately 200 beats/min. She then reverted to
W h e n one e n c o u n t e r s a n a p p a r e n t l y healthy patient with a long history of attacks of paroxysmal tachycardia, t h e electrocardiogram may offer the key to the diagnosis. The clinical syndrome of tachycardia, a short P-Q interval and a wide bizarre QRS complex, as described by Wolff, Parkinson and White 1 (WPW) in 1930, is a frequently recognized entity. The Lown, Ganong, Levine syndrome of tachycardia, a short P-Q interval and no associated QRS abnormalities may also be recognized on the ECG. 2 Recently a prolongation of the Q-T interval has been found to be associated with recurrent arrhythmias. 3 However, m a n y times the ECG does not offer any clue to the diagnosis. With the introduction of the His bundle electrogram technique, more of these patients are being studied. One m a y h a v e bypass pathways of the AV node which function in
From The Department of Medicine, The Methodist Hospital, 506 Sixth Street, Brooklyn, New York. Reprint requests to: Lawrence A. Gould, M.D., The Methodist Hospital, 506 Sixth Street, Brooklyn, NY 11215. 157
158
GOULD ET AL
Fig. 1A. ECGs obtained in Cases 1-3.
sinus rhythm. The patient was subsequently placed on 40 mg of propranolol four times a day with complete control of her symptoms. Case 2. This 61 year old female was admitted to the hospital on 5/30/75 because of a syncopal episode. The patient had been aware of palpitations for a six year period. On six separate occasions the palpitations were followed by syncopal episodes. On examination her blood pressure was 140/80 m m H g and the pulse rate was 75/min. The lungs were clear. There were no m u r m u r s or gallops. The liver was not palpable and there was no peripheral edema. An ECG revealed a n o r m a l sinus r h y t h m with a PR interval of 0.16 sec and a QRS duration of 0.08 sec. A delta wave was not seen (Fig. 1). A His bundle electrogram with right atrial pacing showed unchanged AH intervals from 100 to 150 beats/min (Table I). Ventricular pacing at rates of 100-140 beats/rain showed unchanged pacing spike to A intervals. The patient was placed on 40 mg of propranolol four times a day with complete control of her symptoms. Case 3. This 61 year old female was admitted to t h e hospital on 11/30/75 because of a syn-
copal episode. She was in good health until F e b r u a r y 1974 when she developed severe chest pains. She was hospitalized and told t h a t she had a myocardial infarction. Ventricular premature beats were observed and she was placed on propranolol and procaine a m i d e . In S e p t e m b e r 1975 t h e s y n c o p a l episodes started. They were not preceded by chest pains or by palpitations. On examination her blood pressure was 110/70 m m H g and the pulse rate was 72/min. The lungs were clear. There were no m u r m u r s or gallops. The liver was not palpable and there was no peripheral edema. An ECG revealed a normal sinus r h y t h m with a PR interval of 0.16 sec and a QRS duration of .08 sec (Fig. 1). The T waves were inverted in V1-V6. The serum enzymes were within normal limits. A His bundle electrogram with right atrial pacing showed essentially unchanged AH intervals (Table 1). The patient was subsequently placed on propranolol 20 mg four times a day and procaine amide 250 mg four times a day w i t h c o m p l e t e c o n t r o l of t h e s y n c o p a l episodes. Case 4. This 45 year old female was admitted J. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
NORMAL ECGS, ACCESSORY PATHWAYS AND PTS
159
Fig. lB. ECGs obtained in Cases 4-7.
m to the hospital on 6/9/75 because of dizzy spells of six months' duration. She had been aware of palpitations preceding each dizzy episode. There was no history of chest pain. On e x a m i n a t i o n her blood p r e s s u r e was 130/90 m m H g and the pulse rate was 45/min. The lungs were clear. There were no murmurs or gallops. The liver was not palpable and there was no peripheral edema. An ECG revealed a sinus bradycardia with a PR interval of 0.16 sec and a QRS duration of 0.08 sec (Fig. 1). There were nonspecific T wave abnormalities. A His bundle electrogram with right atrial pacing showed essentially unchanged AH intervals (Table 1). Propranolol could not be used because of the slow rate. Therefore a permanent pacemaker was implanted and she was t h e n placed on propJ. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
ranolol 40 mg four times a day. She remains free of symptoms. Case 5. This 61 year old female was admitted to the hospital on 11/6/75 for evaluation of recurrent syncopal episodes. She had had two syncopal episodes and six dizzy spells over a six-year period. She was aware of occasional episodes of palpitations. On examination her blood pressure was 150/90 m m H g and the pulse rate was 85/min. The lungs were clear. There were no m u r m u r s or gallops. The liver was not enlarged and there was no peripheral edema. An ECG r e v e a l e d a n o r m a l sinus r h y t h m with a PR interval of 0.17 sec and a QRS duration of 0.12 sec (Fig. 1). A complete left bundle branch block was present. A His bundle electrogram with right atrial pacing showed no change in the AH intervals (Table
160
G O U L D ET AL
Patient
H-Q
H-S
1.
105 110 120 130 140 150 160 170 180
40 80 80 80 80 80 80 80 80
60 40 40 40 40 40 40 50 50
35 35 35 35 35 35 35 35 35
115 115 115 115 115 115 115 115 115
2.
98 100 110 120 130 140 150 160 170
40 50 50 50 50 50 50 50 50
55 65 65 65 65 65 65 75 80
40 40 40 40 40 40 40 40 40
120 120 120 120 120 120 120 120 120
3.
98 100 110 120 130 140 150
20 20 20 20 20 20 20
80 80 80 80 80 130 140
30 30 30 30 30 30 30
110 110 110 110 110 110 110
4.
60 80 90 100 110 120 130 140 150
35 35 35 35 35 35 35 35 35
80 60 60 60 60 60 70 70 70
40 40 40 40 40 40 40 40 40
120 120 120 120 120 120 120 120 120
5,
100 130 140 150 160
20 40 40 40 40
70 80 80 80 80
40 40 40 40 40
160 160 160 160 160
120 130 140 150 160
20 40 40 40 40
80 80 80 80 85
65 65 65 65 65
155 155 155 155 155
125 150 160 170 180 190
25 50 50 50 50 60
60 75 80 80 80 80
40 40 40 40 40 40
120 120 120 120 120 120
7.
Cardiac Rate
TABLE I Results of His Bundle Electrogram Studies p.A or p.IA A-H
Conduction valuesat the slowest heart rate in each patient were obtained without pacing. J. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
NORMAL ECGS, ACCESSORY PATHWAYS AND PTS
161
Fig. 2. Admission ECG obtained on patient seven revealing atrial flutter with a 1:1 AV conduction.
1). During the procedure, bouts of supraventricular tachycardia with a ventricular rate of 170/min were documented. The patient was placed on propranalol 40 mg four times a day and procaine amide 250 mg four times a day with complete control of her symptoms. Case 6. This 58 year old female was admitted to the hospital on 8/1/75 because of a syncopal e p i s o d e . She d e n i e d a n y o t h e r c a r d i a c symptoms. On examination her blood pressure was 120/80 m m H g and the pulse rate was 100/min. The lungs were clear. There was an $4 gallop. The liver was not palpable and there was no peripheral edema. An ECG revealed a sinus tachycardia with a PR interval of.16 sec and a QRS duration of.09 sec (Fig. 1). An antero-septal infarction was present. Serial ECGs and elevated serum enzymes were compatible with an acute infarction. In view of the syncopal episode, a His bundle electrocardiogram with right atrial pacing was accomplished on 8/20/75. An essentially unchanged AH interval was observed with pacing (Table 1). The patient had a fatal carJ. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
diac a r r e s t on 8/24/75 due to v e n t r i c u l a r fibrillation. Case 7. This 58 year old male was admitted to the hospital on 3/10/76 with the chief complaint of shortness of breath, palpitations and near syncope. The patient had never been aware of any similar episodes in the past. On examination the blood pressure was 120/80 m m H g and t h e pulse r a t e was e x t r e m e l y rapid. The neck veins were enlarged. There were rhonchi and wheezes in the lung fields. T h e r e were no m u r m u r s . The a b d o m i n a l e x a m i n a t i o n was n o r m a l . T h e r e w a s no peripheral edema. An ECG revealed a probable atrial flutter with 1:1 AV conduction. The ventricular response was 280 beats/min (Fig. 2). Ten mg of tensilon was given intravenously and the patient then reverted to normal sinus rhythm. The PR interval was .16 sec and the QRS duration was .08 sec (Fig. 1). A His bundle electrogram with right atrial pacing showed unchanged AH intervals at all pacing rates (Table 1, Fig. 3). Similarly, ventricular pacing rates of 150, 160, 170 and 180
162
GOULD ET AL
Fig. 3. His bundle electrograms obtained in patient seven with right atrial pacing rate of 150 (left) and 190 beats/min (right). Note the minimal change in the AH interval.
revealed the identical pacing impulse to A intervals of 140 msec (Fig. 4). In addition, the refractory periods of the AV conduction system were determined by the extrastimulus method. The atria were paced by the drive stimulus (S1) at a rate of 400 msec, and a p r e m a t u r e atrial s t i m u l u s ($2) was introduced after every t e n t h drive a t r i a l beat. Programmed atrial stimuli were introduced utilizing a stimulus isolation box to prevent current leakage. Standard ECG leads I, II, III, the high atrial electrogram and a His bundle electrogram were recorded simultaneously on an Electronics For Medicine Recorder. It is of interest t h a t an $2 introduced at 380, 360, 340, 320, 300 and 280 msec, respectively, produced a constant A2-H2 interval of 80 msec. However, with an $2 introduced at 260,240, 220 and 200 msec, the A2-H2 interval was now 140 msec, while at the $2 value of 180 a n d 175 msec, t h e A2-H2 i n t e r v a l now reached 150 msec (Fig. 5). This signifies a conduction delay at the level of the AV node. Only at 170 msec was the effective refractory period of the atrium reached (Fig. 6). The patient was then placed on propranolol 40 mg four times a day and procaine amide 250 mg qid.
DISCUSSION
Fig. 4. Right ventricular pacing at 180 beats/rain produces a pacing stimulus to A interval of 140 msec.
Four basic features typify the usual electrocardiogram of a patient with the WPW syndrome. 1) P-R interval less t h a n 120 msec during sinus rhythm. 2) QRS complex duration greater t h a n 120 msec with a slurred slow rising onset of the R wave upstroke in some leads (delta wave) and usually normal t e r m i n a l QRS portion. 3) Secondary ST-T wave changes which are usually directed opposite to the major delta and QRS vectors. 4) Paroxysmal tachyarrhythmias in 40 to 80% of patients. In addition to patients who demonstrate ECGs with these four characteristics, other patients may possess variants of the pre-excitation syndrome, characterized by normal or prolonged P-R interval, or a short P-R interval and QRS with normal duration but which has a small delta wave. 7 Various theories have been suggested to explain the WPW syndrome. Most workers now believe t h a t there is an accessory pathway, and cond u c t i o n b y p a s s e s t h e n o r m a l A-V nodebundle-of-His route to pre-excite the ventricles ahead of the impulse traveling down the n o r m a l pathway, s It has been shown t h a t stressing of the A-V node by means of atrial p a c i n g r e s u l t s in p r o l o n g e d c o n d u c t i o n through this path. This can u n e a r t h the existence of an accessory bundle and establish the diagnosis of WPW in an otherwise unsusJ. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
NORMAL ECGS, ACCESSORY PATHWAYS AND PTS
163
Fig. 5. Measurement of the effective refractory period of the atrium. Each panel is organized as follows: From top to bottom, standard leads [, II, III, high right atrial electrogram (t-IRA) and His bundle electrogram (HBE). The basic paced atrial cycle is 400 msec. Note that A2 conducts to the His Purkinje system and ventricle at an A1-A2 interval of 175 msec.
Fig. 6. When the A1-A2 interval is decreased to 170 msec, block of A2 above the atria occurs and the effective r e f r a c t o r y period of t h e atrium is reached.
pected or doubtful case. With atrial pacing, delta waves will appear and the A-V interval remains fixed at the expense of H-V interval shortening. E v e n t u a l l y the H activation follows the onset of ventricular activation. 9 In our present series of patients, the P-R intervals have been normal in m a n y ECGs. The QRS interval has also been of normal duration in all but the one patient with a complete left bundle branch block. No delta waves have ever been demonstrated either by serial elect r o c a r d i o g r a m s or by v e c t o r c a r d i o g r a m s . F u r t h e r , the His electrogram studies with atrial pacing did not elicit a WPW response. In the His bundle electrogram studies of patients with the Lown, Ganong, Levine syn-
J. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
drome, varying responses have been reported. Mandel and his co-workers noted a short H-V time in t h e i r t h r e e patients. 1~ Castellanos and his associates 11 found t h a t shortening of the P-R interval was due to shortening of the A-H interval. In one of t h e i r patients, the A-H interval remained constant during atrial pacing, signifying t h a t the area of normal A-V delay was bypassed. Caracta and his group TM studied 18 subjects with a t r i a l pacing and t h r e e responses were observed. T h i r t e e n subjects showed a progressive increase in t h e A-H interval similar to a normal response, but to a lesser degree. Three subjects showed an initial increase in the A-H interval at low paced rates, followed by a p l a t e a u response
164
GOULD ET AL
and a further increase at higher rates. Two subjects showed no significant increase in the A-H interval with atrial pacing. Narula 4 analyzed antegrade and retrograde conduction times in 124 patients without any evidence of antegrade pre-excitation. Nineteen patients in this series had unchanged retrograde conduction times even with rapid ventricular pacing rates. However, atrial pacing elicited a normal response with antegrade conduction via the AV node. These findings signified a bypass pathway functioning only in a retrograde direction. It is of interest that eight of these 19 patients gave a history of p a l p i t a t i o n s and showed ECG evidence of paroxysmal supraventricular tachycardias. The seven subjects in this study had several features in common. They all were presented with syncopal episodes. The history of palpitations was elicited in five of the patients. The e l e c t r o c a r d i o g r a m did not r e v e a l a preexcitation pattern, a short PR interval or a prolonged QT interval. The His bundle elect r o g r a m studies in all of the patients showed an essentially unchanged AH interval with atrial pacing rates up to 180 beats/min. This can only be explained by a total bypass of the AV node. Two of the patients were also paced from the ventricle, and an unchanged pacing stimulus to A wave interval was observed. This signifies in these patients a functioning bypass pathway in the retrograde direction as well. These observations provide a unified concept to the spectrum of accessory pathways. It is well known t h a t in classical WPW syndrome there may be functioning pathways in both the antegrade and retrograde direction or only in the antegrade direction. Narula 4 has recently demonstrated t h a t retrograde conduction can occur via a bypass fiber in a patient with a normal ECG. Based on our present study, antegrade conduction via a bypass tract can also occur even if the ECG is normal. Thus, it would appear t h a t preexcitation cannot be eliminated as a diagnostic possibility even if the ECG is normal. It has long been recognized t h a t precipitation of atrial fibrillation in a patient with the WPW syndrome m a y lead to rapid ventricular rates with hemodynamic decompensation. This results from conduction via the accessory pathway. Similarly, in patient #1 an episode of p a r o x y s m a l a t r i a l f i b r i l l a t i o n w a s documented with ventricular rates greater t h a n 200 beats/min. In patient #7 atrial flutter with 1:1 AV conduction led to a ventricular response of 280 beats/min. These r h y t h m s can adequately explain the syncopal episodes these patients had experienced through the years. Prevention of these life-threatening cardiac a r r h y t h m i a s is therefore the main
therapeutic goal. Propranolol and quinidine or procaine amide have been advocated in the prevention of a r r h y t h m i a s in classic WPW syndromes. Based on this information, most of the patients in this study have been placed on these medications. The results have been most satisfactory in t h a t there have been no recurrences of dizzy spells or fainting spells in any of these patients. Long term follow up will be required, however, to evaluate the efficacy of these anti-arrhythmic agents.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
REFERENCES WOLFF, L, PARKINSON, J AND WHITE, P B: Bundle branch block with short PR interval in healthy young people prone to paroxysmal tachycardia. Am Heart J 5:685, 1930 LOWN,B, GANONG,W F ANDLEVINE, S A: The syndrome of short P-R interval, normal QRS complex and paroxysmal rapid heart action. Circulation 5:693, 1952 KARHANEN, P, LUOMANMAKI,K, HELKKLA, J AND EISALO, A: Syncope and QT prolongation without deafness: Romano-Ward Syndrome. Am Heart J 80:820, 1970 NARULA, O S: Retrograde pre-excitation comparison of antegrade and retrograde conduction intervals in man. Circulation 50:1129, 1974 GOULD,L, REDDY, C V R AND DEL NUNZIO, R: Recurrent tachycardias due to an accessory pathway. J. Electrocardiol 9:259, 1976 WIT, A L, WEISS, M B, BERKOWITZ,W D, ROSEN, K M, STEINER,E AND DAMATO,A N: Patterns of atrioventricular conduction in the human heart. Circ Res 27:345, 1970 BURCH, G E AND KIMBALL,J L: Notes on the similarity of the QRS complex configurations in the Wolff-Parkinson-White Syndrome. Am Heart J 32:450, 1946 WOLFERTH, C C AND WOOD, F C: The mechanism of production of short P-R intervals and prolonged QRS complexes in patients with presumably undamaged hearts: Hypothesis of an accessory pathway of auriculoventricular conduction (bundle of Kent). Am Heart J 8:297, 1933 CASTELLANOS, A, JR, CASTILLO, C A AND AGHA,A S: Contribution of His bundle recordings to the understanding of clinical arrhythmias. Am J Cardiol 28:499, 1971 MANDEL, W J, DANZIG, R AND HAYAKAWA,H: Lown-Ganong-Levine Syndrome -- A study using His bundle electrograms. Circulation 44:696, 1971 CASTELLANOS,A, JR, CASTILLO,C A, AGHA,A S ANDTESSLER,M: His bundle electrograms on patients with short P-R intervals, narrow QRS complexes and paroxysmal tachycardia. Circulation 93:667, 1971 CARACTA,A R, DAMATO,A N, GALLAGHER,J J, JOSEPHSON, M E, VARGHESE, P J, LAU, S H AND WESTURA, E G: Electrophysiological studies in the Lown-Ganong-Levine syndrome. Circulation 46:(Suppl II) 91, 1972
J. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
The Syndrome of Normal Electrocardiograms, Accessory Pathways and Paroxysmal Tachycardias BY LAWRENCE GOULD, M.D., C. V. RAMANA REDDY, M.D., W. CHUA, M.D., C. SWAMY, M.D. AND J. C. DORISMOND, M.D.
SUMMARY
the retrograde direction only. Antegrade conduction is via the AV node and therefore the ECG does not reveal any characteristic abnormalities. 4 Recently we described a patient with recurrent tachycardias, no electrocardiographic evidence of pre-excitation and ant e g r a d e conduction t h a t bypassed t h e AV node. ~ Over the past year we have recognized six additional patients with the identical condition. This paper will describe the clinical and conduction studies in this new entity.
Tachycardias may be associated with the pre-excitation syndrome, a short PR interval or a prolonged QT interval. This report describes seven patients whose electrocardiograms (ECGs) did not reveal any of the above-named conditions. All of the patients presented with syncopal episodes, and the history of palpitations was elicited in five of the patients. His bundle electrogram studies in all of the patients showed an essentially unchanged AH interval with atrial pacing rates up to 180 beats/rain. This can only be explained by a total bypass of the AV node. Two of the patients were also paced from the ventricle, and an unchanged pacing stimulus to A wave interval was observed. This signifies in these patients a functioning bypass pathway in the retrograde direction as well. Thus it would appear that pre-excitation cannot be eliminated as a diagnostic possibility even if the ECG is normal.
CASE REPORTS Case 1. This 78 year old female was admitted to the hospital on 11/16/74 after fainting in her physician's office. The patient became aware of palpitations at the age of nine. These episodes occurred once a month and continued throughout the years. On frequent occasions the palpitations were followed by syncopal episodes. Four months prior to admission, she developed an episode of severe chest pain, and an inferior wall myocardial infarction was diagnosed. She subsequently made an uneventful recovery. On the day of examination she had visited her physician for a check-up examination. An examination revealed no detectable blood pressure and a rapid cardiac rate. She t h e n s p o n t a n e o u s l y r e v e r t e d to sinus r h y t h m with recovery of consciousness. She was immediately transferred to the hospital for admission. On examination, her blood pressure was 130/80 m m H g and the pulse rate was 80 beats/min. The neck veins were not prominent and the lungs were clear. There were no m u r m u r s or gallops. The liver was not palpable a n d t h e r e was no peripheral edema. An ECG revealed a PR interval of 0.17 sec and a QRS duration of 0.08 sec (Fig. 1). A delta wave was not present. There was evidence of the old inferior wall myocardial infarction. In order to evaluate the conduction system, a His bundle electrogram was obtained with right atrial pacing. The results are listed in Table I. With atrial pacing rates of 110 to 180 beats/rain, the AH and HV intervals remained essentially unchanged. At the conclusion of the study the patient spontaneously developed atrial fibrillation with a ventricular response of approximately 200 beats/min. She then reverted to
W h e n one e n c o u n t e r s a n a p p a r e n t l y healthy patient with a long history of attacks of paroxysmal tachycardia, t h e electrocardiogram may offer the key to the diagnosis. The clinical syndrome of tachycardia, a short P-Q interval and a wide bizarre QRS complex, as described by Wolff, Parkinson and White 1 (WPW) in 1930, is a frequently recognized entity. The Lown, Ganong, Levine syndrome of tachycardia, a short P-Q interval and no associated QRS abnormalities may also be recognized on the ECG. 2 Recently a prolongation of the Q-T interval has been found to be associated with recurrent arrhythmias. 3 However, m a n y times the ECG does not offer any clue to the diagnosis. With the introduction of the His bundle electrogram technique, more of these patients are being studied. One m a y h a v e bypass pathways of the AV node which function in
From The Department of Medicine, The Methodist Hospital, 506 Sixth Street, Brooklyn, New York. Reprint requests to: Lawrence A. Gould, M.D., The Methodist Hospital, 506 Sixth Street, Brooklyn, NY 11215. 157
158
GOULD ET AL
Fig. 1A. ECGs obtained in Cases 1-3.
sinus rhythm. The patient was subsequently placed on 40 mg of propranolol four times a day with complete control of her symptoms. Case 2. This 61 year old female was admitted to the hospital on 5/30/75 because of a syncopal episode. The patient had been aware of palpitations for a six year period. On six separate occasions the palpitations were followed by syncopal episodes. On examination her blood pressure was 140/80 m m H g and the pulse rate was 75/min. The lungs were clear. There were no m u r m u r s or gallops. The liver was not palpable and there was no peripheral edema. An ECG revealed a n o r m a l sinus r h y t h m with a PR interval of 0.16 sec and a QRS duration of 0.08 sec. A delta wave was not seen (Fig. 1). A His bundle electrogram with right atrial pacing showed unchanged AH intervals from 100 to 150 beats/min (Table I). Ventricular pacing at rates of 100-140 beats/rain showed unchanged pacing spike to A intervals. The patient was placed on 40 mg of propranolol four times a day with complete control of her symptoms. Case 3. This 61 year old female was admitted to t h e hospital on 11/30/75 because of a syn-
copal episode. She was in good health until F e b r u a r y 1974 when she developed severe chest pains. She was hospitalized and told t h a t she had a myocardial infarction. Ventricular premature beats were observed and she was placed on propranolol and procaine a m i d e . In S e p t e m b e r 1975 t h e s y n c o p a l episodes started. They were not preceded by chest pains or by palpitations. On examination her blood pressure was 110/70 m m H g and the pulse rate was 72/min. The lungs were clear. There were no m u r m u r s or gallops. The liver was not palpable and there was no peripheral edema. An ECG revealed a normal sinus r h y t h m with a PR interval of 0.16 sec and a QRS duration of .08 sec (Fig. 1). The T waves were inverted in V1-V6. The serum enzymes were within normal limits. A His bundle electrogram with right atrial pacing showed essentially unchanged AH intervals (Table 1). The patient was subsequently placed on propranolol 20 mg four times a day and procaine amide 250 mg four times a day w i t h c o m p l e t e c o n t r o l of t h e s y n c o p a l episodes. Case 4. This 45 year old female was admitted J. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
NORMAL ECGS, ACCESSORY PATHWAYS AND PTS
159
Fig. lB. ECGs obtained in Cases 4-7.
m to the hospital on 6/9/75 because of dizzy spells of six months' duration. She had been aware of palpitations preceding each dizzy episode. There was no history of chest pain. On e x a m i n a t i o n her blood p r e s s u r e was 130/90 m m H g and the pulse rate was 45/min. The lungs were clear. There were no murmurs or gallops. The liver was not palpable and there was no peripheral edema. An ECG revealed a sinus bradycardia with a PR interval of 0.16 sec and a QRS duration of 0.08 sec (Fig. 1). There were nonspecific T wave abnormalities. A His bundle electrogram with right atrial pacing showed essentially unchanged AH intervals (Table 1). Propranolol could not be used because of the slow rate. Therefore a permanent pacemaker was implanted and she was t h e n placed on propJ. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
ranolol 40 mg four times a day. She remains free of symptoms. Case 5. This 61 year old female was admitted to the hospital on 11/6/75 for evaluation of recurrent syncopal episodes. She had had two syncopal episodes and six dizzy spells over a six-year period. She was aware of occasional episodes of palpitations. On examination her blood pressure was 150/90 m m H g and the pulse rate was 85/min. The lungs were clear. There were no m u r m u r s or gallops. The liver was not enlarged and there was no peripheral edema. An ECG r e v e a l e d a n o r m a l sinus r h y t h m with a PR interval of 0.17 sec and a QRS duration of 0.12 sec (Fig. 1). A complete left bundle branch block was present. A His bundle electrogram with right atrial pacing showed no change in the AH intervals (Table
160
G O U L D ET AL
Patient
H-Q
H-S
1.
105 110 120 130 140 150 160 170 180
40 80 80 80 80 80 80 80 80
60 40 40 40 40 40 40 50 50
35 35 35 35 35 35 35 35 35
115 115 115 115 115 115 115 115 115
2.
98 100 110 120 130 140 150 160 170
40 50 50 50 50 50 50 50 50
55 65 65 65 65 65 65 75 80
40 40 40 40 40 40 40 40 40
120 120 120 120 120 120 120 120 120
3.
98 100 110 120 130 140 150
20 20 20 20 20 20 20
80 80 80 80 80 130 140
30 30 30 30 30 30 30
110 110 110 110 110 110 110
4.
60 80 90 100 110 120 130 140 150
35 35 35 35 35 35 35 35 35
80 60 60 60 60 60 70 70 70
40 40 40 40 40 40 40 40 40
120 120 120 120 120 120 120 120 120
5,
100 130 140 150 160
20 40 40 40 40
70 80 80 80 80
40 40 40 40 40
160 160 160 160 160
120 130 140 150 160
20 40 40 40 40
80 80 80 80 85
65 65 65 65 65
155 155 155 155 155
125 150 160 170 180 190
25 50 50 50 50 60
60 75 80 80 80 80
40 40 40 40 40 40
120 120 120 120 120 120
7.
Cardiac Rate
TABLE I Results of His Bundle Electrogram Studies p.A or p.IA A-H
Conduction valuesat the slowest heart rate in each patient were obtained without pacing. J. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
NORMAL ECGS, ACCESSORY PATHWAYS AND PTS
161
Fig. 2. Admission ECG obtained on patient seven revealing atrial flutter with a 1:1 AV conduction.
1). During the procedure, bouts of supraventricular tachycardia with a ventricular rate of 170/min were documented. The patient was placed on propranalol 40 mg four times a day and procaine amide 250 mg four times a day with complete control of her symptoms. Case 6. This 58 year old female was admitted to the hospital on 8/1/75 because of a syncopal e p i s o d e . She d e n i e d a n y o t h e r c a r d i a c symptoms. On examination her blood pressure was 120/80 m m H g and the pulse rate was 100/min. The lungs were clear. There was an $4 gallop. The liver was not palpable and there was no peripheral edema. An ECG revealed a sinus tachycardia with a PR interval of.16 sec and a QRS duration of.09 sec (Fig. 1). An antero-septal infarction was present. Serial ECGs and elevated serum enzymes were compatible with an acute infarction. In view of the syncopal episode, a His bundle electrocardiogram with right atrial pacing was accomplished on 8/20/75. An essentially unchanged AH interval was observed with pacing (Table 1). The patient had a fatal carJ. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
diac a r r e s t on 8/24/75 due to v e n t r i c u l a r fibrillation. Case 7. This 58 year old male was admitted to the hospital on 3/10/76 with the chief complaint of shortness of breath, palpitations and near syncope. The patient had never been aware of any similar episodes in the past. On examination the blood pressure was 120/80 m m H g and t h e pulse r a t e was e x t r e m e l y rapid. The neck veins were enlarged. There were rhonchi and wheezes in the lung fields. T h e r e were no m u r m u r s . The a b d o m i n a l e x a m i n a t i o n was n o r m a l . T h e r e w a s no peripheral edema. An ECG revealed a probable atrial flutter with 1:1 AV conduction. The ventricular response was 280 beats/min (Fig. 2). Ten mg of tensilon was given intravenously and the patient then reverted to normal sinus rhythm. The PR interval was .16 sec and the QRS duration was .08 sec (Fig. 1). A His bundle electrogram with right atrial pacing showed unchanged AH intervals at all pacing rates (Table 1, Fig. 3). Similarly, ventricular pacing rates of 150, 160, 170 and 180
162
GOULD ET AL
Fig. 3. His bundle electrograms obtained in patient seven with right atrial pacing rate of 150 (left) and 190 beats/min (right). Note the minimal change in the AH interval.
revealed the identical pacing impulse to A intervals of 140 msec (Fig. 4). In addition, the refractory periods of the AV conduction system were determined by the extrastimulus method. The atria were paced by the drive stimulus (S1) at a rate of 400 msec, and a p r e m a t u r e atrial s t i m u l u s ($2) was introduced after every t e n t h drive a t r i a l beat. Programmed atrial stimuli were introduced utilizing a stimulus isolation box to prevent current leakage. Standard ECG leads I, II, III, the high atrial electrogram and a His bundle electrogram were recorded simultaneously on an Electronics For Medicine Recorder. It is of interest t h a t an $2 introduced at 380, 360, 340, 320, 300 and 280 msec, respectively, produced a constant A2-H2 interval of 80 msec. However, with an $2 introduced at 260,240, 220 and 200 msec, the A2-H2 interval was now 140 msec, while at the $2 value of 180 a n d 175 msec, t h e A2-H2 i n t e r v a l now reached 150 msec (Fig. 5). This signifies a conduction delay at the level of the AV node. Only at 170 msec was the effective refractory period of the atrium reached (Fig. 6). The patient was then placed on propranolol 40 mg four times a day and procaine amide 250 mg qid.
DISCUSSION
Fig. 4. Right ventricular pacing at 180 beats/rain produces a pacing stimulus to A interval of 140 msec.
Four basic features typify the usual electrocardiogram of a patient with the WPW syndrome. 1) P-R interval less t h a n 120 msec during sinus rhythm. 2) QRS complex duration greater t h a n 120 msec with a slurred slow rising onset of the R wave upstroke in some leads (delta wave) and usually normal t e r m i n a l QRS portion. 3) Secondary ST-T wave changes which are usually directed opposite to the major delta and QRS vectors. 4) Paroxysmal tachyarrhythmias in 40 to 80% of patients. In addition to patients who demonstrate ECGs with these four characteristics, other patients may possess variants of the pre-excitation syndrome, characterized by normal or prolonged P-R interval, or a short P-R interval and QRS with normal duration but which has a small delta wave. 7 Various theories have been suggested to explain the WPW syndrome. Most workers now believe t h a t there is an accessory pathway, and cond u c t i o n b y p a s s e s t h e n o r m a l A-V nodebundle-of-His route to pre-excite the ventricles ahead of the impulse traveling down the n o r m a l pathway, s It has been shown t h a t stressing of the A-V node by means of atrial p a c i n g r e s u l t s in p r o l o n g e d c o n d u c t i o n through this path. This can u n e a r t h the existence of an accessory bundle and establish the diagnosis of WPW in an otherwise unsusJ. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
NORMAL ECGS, ACCESSORY PATHWAYS AND PTS
163
Fig. 5. Measurement of the effective refractory period of the atrium. Each panel is organized as follows: From top to bottom, standard leads [, II, III, high right atrial electrogram (t-IRA) and His bundle electrogram (HBE). The basic paced atrial cycle is 400 msec. Note that A2 conducts to the His Purkinje system and ventricle at an A1-A2 interval of 175 msec.
Fig. 6. When the A1-A2 interval is decreased to 170 msec, block of A2 above the atria occurs and the effective r e f r a c t o r y period of t h e atrium is reached.
pected or doubtful case. With atrial pacing, delta waves will appear and the A-V interval remains fixed at the expense of H-V interval shortening. E v e n t u a l l y the H activation follows the onset of ventricular activation. 9 In our present series of patients, the P-R intervals have been normal in m a n y ECGs. The QRS interval has also been of normal duration in all but the one patient with a complete left bundle branch block. No delta waves have ever been demonstrated either by serial elect r o c a r d i o g r a m s or by v e c t o r c a r d i o g r a m s . F u r t h e r , the His electrogram studies with atrial pacing did not elicit a WPW response. In the His bundle electrogram studies of patients with the Lown, Ganong, Levine syn-
J. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977
drome, varying responses have been reported. Mandel and his co-workers noted a short H-V time in t h e i r t h r e e patients. 1~ Castellanos and his associates 11 found t h a t shortening of the P-R interval was due to shortening of the A-H interval. In one of t h e i r patients, the A-H interval remained constant during atrial pacing, signifying t h a t the area of normal A-V delay was bypassed. Caracta and his group TM studied 18 subjects with a t r i a l pacing and t h r e e responses were observed. T h i r t e e n subjects showed a progressive increase in t h e A-H interval similar to a normal response, but to a lesser degree. Three subjects showed an initial increase in the A-H interval at low paced rates, followed by a p l a t e a u response
164
GOULD ET AL
and a further increase at higher rates. Two subjects showed no significant increase in the A-H interval with atrial pacing. Narula 4 analyzed antegrade and retrograde conduction times in 124 patients without any evidence of antegrade pre-excitation. Nineteen patients in this series had unchanged retrograde conduction times even with rapid ventricular pacing rates. However, atrial pacing elicited a normal response with antegrade conduction via the AV node. These findings signified a bypass pathway functioning only in a retrograde direction. It is of interest that eight of these 19 patients gave a history of p a l p i t a t i o n s and showed ECG evidence of paroxysmal supraventricular tachycardias. The seven subjects in this study had several features in common. They all were presented with syncopal episodes. The history of palpitations was elicited in five of the patients. The e l e c t r o c a r d i o g r a m did not r e v e a l a preexcitation pattern, a short PR interval or a prolonged QT interval. The His bundle elect r o g r a m studies in all of the patients showed an essentially unchanged AH interval with atrial pacing rates up to 180 beats/min. This can only be explained by a total bypass of the AV node. Two of the patients were also paced from the ventricle, and an unchanged pacing stimulus to A wave interval was observed. This signifies in these patients a functioning bypass pathway in the retrograde direction as well. These observations provide a unified concept to the spectrum of accessory pathways. It is well known t h a t in classical WPW syndrome there may be functioning pathways in both the antegrade and retrograde direction or only in the antegrade direction. Narula 4 has recently demonstrated t h a t retrograde conduction can occur via a bypass fiber in a patient with a normal ECG. Based on our present study, antegrade conduction via a bypass tract can also occur even if the ECG is normal. Thus, it would appear t h a t preexcitation cannot be eliminated as a diagnostic possibility even if the ECG is normal. It has long been recognized t h a t precipitation of atrial fibrillation in a patient with the WPW syndrome m a y lead to rapid ventricular rates with hemodynamic decompensation. This results from conduction via the accessory pathway. Similarly, in patient #1 an episode of p a r o x y s m a l a t r i a l f i b r i l l a t i o n w a s documented with ventricular rates greater t h a n 200 beats/min. In patient #7 atrial flutter with 1:1 AV conduction led to a ventricular response of 280 beats/min. These r h y t h m s can adequately explain the syncopal episodes these patients had experienced through the years. Prevention of these life-threatening cardiac a r r h y t h m i a s is therefore the main
therapeutic goal. Propranolol and quinidine or procaine amide have been advocated in the prevention of a r r h y t h m i a s in classic WPW syndromes. Based on this information, most of the patients in this study have been placed on these medications. The results have been most satisfactory in t h a t there have been no recurrences of dizzy spells or fainting spells in any of these patients. Long term follow up will be required, however, to evaluate the efficacy of these anti-arrhythmic agents.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
REFERENCES WOLFF, L, PARKINSON, J AND WHITE, P B: Bundle branch block with short PR interval in healthy young people prone to paroxysmal tachycardia. Am Heart J 5:685, 1930 LOWN,B, GANONG,W F ANDLEVINE, S A: The syndrome of short P-R interval, normal QRS complex and paroxysmal rapid heart action. Circulation 5:693, 1952 KARHANEN, P, LUOMANMAKI,K, HELKKLA, J AND EISALO, A: Syncope and QT prolongation without deafness: Romano-Ward Syndrome. Am Heart J 80:820, 1970 NARULA, O S: Retrograde pre-excitation comparison of antegrade and retrograde conduction intervals in man. Circulation 50:1129, 1974 GOULD,L, REDDY, C V R AND DEL NUNZIO, R: Recurrent tachycardias due to an accessory pathway. J. Electrocardiol 9:259, 1976 WIT, A L, WEISS, M B, BERKOWITZ,W D, ROSEN, K M, STEINER,E AND DAMATO,A N: Patterns of atrioventricular conduction in the human heart. Circ Res 27:345, 1970 BURCH, G E AND KIMBALL,J L: Notes on the similarity of the QRS complex configurations in the Wolff-Parkinson-White Syndrome. Am Heart J 32:450, 1946 WOLFERTH, C C AND WOOD, F C: The mechanism of production of short P-R intervals and prolonged QRS complexes in patients with presumably undamaged hearts: Hypothesis of an accessory pathway of auriculoventricular conduction (bundle of Kent). Am Heart J 8:297, 1933 CASTELLANOS, A, JR, CASTILLO, C A AND AGHA,A S: Contribution of His bundle recordings to the understanding of clinical arrhythmias. Am J Cardiol 28:499, 1971 MANDEL, W J, DANZIG, R AND HAYAKAWA,H: Lown-Ganong-Levine Syndrome -- A study using His bundle electrograms. Circulation 44:696, 1971 CASTELLANOS,A, JR, CASTILLO,C A, AGHA,A S ANDTESSLER,M: His bundle electrograms on patients with short P-R intervals, narrow QRS complexes and paroxysmal tachycardia. Circulation 93:667, 1971 CARACTA,A R, DAMATO,A N, GALLAGHER,J J, JOSEPHSON, M E, VARGHESE, P J, LAU, S H AND WESTURA, E G: Electrophysiological studies in the Lown-Ganong-Levine syndrome. Circulation 46:(Suppl II) 91, 1972
J. ELECTROCARDIOLOGY, VOL. 10, NO. 2, 1977