Journal of lnternal Medicine 1991; 2 2 9 : 375-376
ADONIS 0954682091000688
Case report Third-degree atrioventricular block in an athlete A. HERNANDEZ-MADRID, C. MORO, E. MARfN HUIZRTA & I. R A Y 0 From the Arrhythmia Unit. Ramon y Cujal Hospital, Madrid. S p i n
Abstract. Hernandez-Madrid A, Moro C, Marin Huerta E, Ray0 I (Arrhythmia Unit, R a m h y Cajal Hospital, Madrid, Spain). Third-degree atrioventricular block in an athlete. Journal of Internal Medicine 1991 : 229: 375-376. There is a wide spectrum of changes in the resting electrocardiograms of athletes. We here present a case of third-degree atrioventricular block in an asymptomatic young
athlete. Keywords: atrioventricular block, exercise, hypervagotonia.
Introduction The athlete's heart shows many adaptations, and these have recently been reviewed [l]. Changes in heart rhythm, atrioventricular (AV) conduction and repolarization are found [2]. Although third-degree atrioventricular (AV) block has been reported previously, this case had a n unusually long follow-up.
Case report The patient was a 17-year-old man. His training consisted exclusively of aerobic exercise, 2 hours a day, for 6 days a week. An electrocardiogram revealed a third-degree AV block with ventricular rates ranging from 30 to 40 beats min-' (Fig. 1). His physical examination, chest X-ray film, M-mode and two-dimensional echocardiogram were considered to be normal. Treadmill exercise testing was performed. The patient's heart rate increased to 190 beats min-', and the electrocardiogram became normal, with 1: 1 conduction. When exercise was stopped, the thirddegree AV block reappeared. A 24-hour ambulatory electrocardiogram recording showed third-degree AV block. Average, maximum and minimum ventricular rates were 41. 100 and 20 beats min-', respectively. The atrial rate varied from 6 0 to 120 beats min-'. An invasive electrophysiological study was performed in the postabsorptive non-sedated state, and revealed an intranodal block. The AV block was
associated with sinoatrial slowing, both being the result of vagal effects on the sinus and atrioventricular nodes. After intravenous injection of atropine, sinus rhythm with 1: 1 AV conduction was restored (Fig. 1). The patient was treated with propantheline, 15 mg, three times daily, and the dose was adjusted to eliminate side-effects. He was advised to decrease the intensity of training. During 4 years of follow-up no disease was identified. Persistent bradycardia was observed, with alternating sinus and nodal rhythms. The patient has remained asymptomatic and continues to play sports, albeit at reduced intensity.
Discussion The prevalence of first- and second-degree AV block in dynamic athletes varied between 6-33% and 2.4-10% respectively, and the frequency of thirddegree AV is not known [l]. The degree of AV block is closely related to the intensity of training. The presentation of AV block in athletes is probably an expression of relative vagal dominance [3]. As the relative effects of the sympathetic and parasympathetic systems on the sinus and AV node may differ, atrioventricular block mediated by increased vagal tone may or may not be associated with decreasing sinus rate. Sometimes there is no change in sinus rate, or even an increase at the time of the appearance of AV block. Possible mechanisms for hypervagotonia isolated to the atrioventricular node 3 75
376
A. HERNANDEZ-MADRID et al. I
rA
- , - - I
Pig. 1. The effects of atropine administration : (a) the basal electrocardiogram reveals third-degree atrioventricular block: (b) after atropine. the electrocardiogram shows sinus rhythm with 1 : 1 atrioventricular conduction.
may be the presence of separate parallel vagal branches in man, which could become selectively affected [4],an increased sensitivity to acetylcholine, or a decrease in the activity of acetylcholinesterase at the nerve terminal. The physiological nature of the block in this patient was demonstrated by sympathetic-induced manoeuvres and simple methods such as exercise tests or pharmacological tests, so we could confirm that the vagotonia had an important role. These methods help us to rule out a congenital complete AV block [ 51. The electrophysiological testing would not be necessary in cases with a normal response to the atropine test, but should be performed when the atropine test has little effect on the AV conduction [ 61. Electrophysiological testing can be performed in selected cases when clues to a diagnosis cannot be obtained by non-invasive means. The implantation of a pacemaker in symptomatic vagotonia is controversial ; some authors recommend that a pacemaker should be implanted. First we advise the patient to decrease the intensity of training and, if symptoms persist, we treat the patient with oral propantheline [ 51 or theophylline [7]. Pacemaker therapy is necessary if symptoms interfere with the patient's quality of life. Our patient had an asymptomatic complete heart block of a
theoretically reversible nature. We consider that a pacemaker is not indicated in such cases.
References 1 Huston TP. Puffer JC, Roney WH. The athletic heart syndrome.
N E n g l I M e d 1 9 8 5 : 313: 24-32. 2 Dinardo D. Abedin 2. High degree atrioventricular block in a marathoner with 5-year follow-up. Arn Heart ] 1 9 8 7 : 1 1 4-3 : 834-7. 3 Talan DA. Bauernfeind RA. Ashley W el a/.. Twenty-four-hour continuous ECG recordings in long-distance runners. Chest 1982: 82-1 : 19-24. 4 Rubin DA, Niemiski KE. Woolf P et al. Selective hypervagotonia isolated to the atrioventricular node. PACE 1 9 8 8 : 11-1: 1529-32. 5 McLaran CJ. Gersn BJ.Osborn MJ e t a / . Increased vagal tone as an isolated finding in patients undergoing electrophysiological testing for recurrent syncope; response to long-term anticholinergic agents. Br Heart ] 1 9 8 6 : 55: 53-7. 6 G v y S. Danis C. Broustet JPet al. Blocs auriculo-ventriculaires idiopathiques du sujet jeune. Arch Ma1 Coeur 1982; 75: 11-20. 7 Benditt X. Benson DW. Kreitt J et al. Electrophysiologic effects of theophylline in young patients with recurrent symptomatic bradyarrhythmias. Am I Cardiol 1983: 52: 1223-9. Received 22 March 1990, accepted 22 May 1990. Correspondence: Antonio Hernindez-Madrid. MD. Arrhythmia
Unit, Ramon y Cajal Hospital, Carretera de Colmenar Krn.9. 100 Madrid 28034, Spain.
ADONIS 0954682091000688
Case report Third-degree atrioventricular block in an athlete A. HERNANDEZ-MADRID, C. MORO, E. MARfN HUIZRTA & I. R A Y 0 From the Arrhythmia Unit. Ramon y Cujal Hospital, Madrid. S p i n
Abstract. Hernandez-Madrid A, Moro C, Marin Huerta E, Ray0 I (Arrhythmia Unit, R a m h y Cajal Hospital, Madrid, Spain). Third-degree atrioventricular block in an athlete. Journal of Internal Medicine 1991 : 229: 375-376. There is a wide spectrum of changes in the resting electrocardiograms of athletes. We here present a case of third-degree atrioventricular block in an asymptomatic young
athlete. Keywords: atrioventricular block, exercise, hypervagotonia.
Introduction The athlete's heart shows many adaptations, and these have recently been reviewed [l]. Changes in heart rhythm, atrioventricular (AV) conduction and repolarization are found [2]. Although third-degree atrioventricular (AV) block has been reported previously, this case had a n unusually long follow-up.
Case report The patient was a 17-year-old man. His training consisted exclusively of aerobic exercise, 2 hours a day, for 6 days a week. An electrocardiogram revealed a third-degree AV block with ventricular rates ranging from 30 to 40 beats min-' (Fig. 1). His physical examination, chest X-ray film, M-mode and two-dimensional echocardiogram were considered to be normal. Treadmill exercise testing was performed. The patient's heart rate increased to 190 beats min-', and the electrocardiogram became normal, with 1: 1 conduction. When exercise was stopped, the thirddegree AV block reappeared. A 24-hour ambulatory electrocardiogram recording showed third-degree AV block. Average, maximum and minimum ventricular rates were 41. 100 and 20 beats min-', respectively. The atrial rate varied from 6 0 to 120 beats min-'. An invasive electrophysiological study was performed in the postabsorptive non-sedated state, and revealed an intranodal block. The AV block was
associated with sinoatrial slowing, both being the result of vagal effects on the sinus and atrioventricular nodes. After intravenous injection of atropine, sinus rhythm with 1: 1 AV conduction was restored (Fig. 1). The patient was treated with propantheline, 15 mg, three times daily, and the dose was adjusted to eliminate side-effects. He was advised to decrease the intensity of training. During 4 years of follow-up no disease was identified. Persistent bradycardia was observed, with alternating sinus and nodal rhythms. The patient has remained asymptomatic and continues to play sports, albeit at reduced intensity.
Discussion The prevalence of first- and second-degree AV block in dynamic athletes varied between 6-33% and 2.4-10% respectively, and the frequency of thirddegree AV is not known [l]. The degree of AV block is closely related to the intensity of training. The presentation of AV block in athletes is probably an expression of relative vagal dominance [3]. As the relative effects of the sympathetic and parasympathetic systems on the sinus and AV node may differ, atrioventricular block mediated by increased vagal tone may or may not be associated with decreasing sinus rate. Sometimes there is no change in sinus rate, or even an increase at the time of the appearance of AV block. Possible mechanisms for hypervagotonia isolated to the atrioventricular node 3 75
376
A. HERNANDEZ-MADRID et al. I
rA
- , - - I
Pig. 1. The effects of atropine administration : (a) the basal electrocardiogram reveals third-degree atrioventricular block: (b) after atropine. the electrocardiogram shows sinus rhythm with 1 : 1 atrioventricular conduction.
may be the presence of separate parallel vagal branches in man, which could become selectively affected [4],an increased sensitivity to acetylcholine, or a decrease in the activity of acetylcholinesterase at the nerve terminal. The physiological nature of the block in this patient was demonstrated by sympathetic-induced manoeuvres and simple methods such as exercise tests or pharmacological tests, so we could confirm that the vagotonia had an important role. These methods help us to rule out a congenital complete AV block [ 51. The electrophysiological testing would not be necessary in cases with a normal response to the atropine test, but should be performed when the atropine test has little effect on the AV conduction [ 61. Electrophysiological testing can be performed in selected cases when clues to a diagnosis cannot be obtained by non-invasive means. The implantation of a pacemaker in symptomatic vagotonia is controversial ; some authors recommend that a pacemaker should be implanted. First we advise the patient to decrease the intensity of training and, if symptoms persist, we treat the patient with oral propantheline [ 51 or theophylline [7]. Pacemaker therapy is necessary if symptoms interfere with the patient's quality of life. Our patient had an asymptomatic complete heart block of a
theoretically reversible nature. We consider that a pacemaker is not indicated in such cases.
References 1 Huston TP. Puffer JC, Roney WH. The athletic heart syndrome.
N E n g l I M e d 1 9 8 5 : 313: 24-32. 2 Dinardo D. Abedin 2. High degree atrioventricular block in a marathoner with 5-year follow-up. Arn Heart ] 1 9 8 7 : 1 1 4-3 : 834-7. 3 Talan DA. Bauernfeind RA. Ashley W el a/.. Twenty-four-hour continuous ECG recordings in long-distance runners. Chest 1982: 82-1 : 19-24. 4 Rubin DA, Niemiski KE. Woolf P et al. Selective hypervagotonia isolated to the atrioventricular node. PACE 1 9 8 8 : 11-1: 1529-32. 5 McLaran CJ. Gersn BJ.Osborn MJ e t a / . Increased vagal tone as an isolated finding in patients undergoing electrophysiological testing for recurrent syncope; response to long-term anticholinergic agents. Br Heart ] 1 9 8 6 : 55: 53-7. 6 G v y S. Danis C. Broustet JPet al. Blocs auriculo-ventriculaires idiopathiques du sujet jeune. Arch Ma1 Coeur 1982; 75: 11-20. 7 Benditt X. Benson DW. Kreitt J et al. Electrophysiologic effects of theophylline in young patients with recurrent symptomatic bradyarrhythmias. Am I Cardiol 1983: 52: 1223-9. Received 22 March 1990, accepted 22 May 1990. Correspondence: Antonio Hernindez-Madrid. MD. Arrhythmia
Unit, Ramon y Cajal Hospital, Carretera de Colmenar Krn.9. 100 Madrid 28034, Spain.
