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1 AV block
International Journal of Cardiology 132 (2009) e111 – e114 www.elsevier.com/locate/ijcard
Letter to the Editor
Clinical examination should not be forgotten when assessing the level of 2/1 AV block Eloi Marijon ⁎, Nicolas Combes, Serge Boveda, Agustin Bortone, Jamal Najjar, Jean Pierre Donzeau, Jean Paul Albenque Clinique Pasteur, Département de Rythmologie, Toulouse, France Received 10 July 2007; accepted 4 August 2007 Available online 26 November 2007
Abstract The authors underline the importance of carrying out a simple clinical examination to assess the level of two-to-one auriculoventricular block before any invasive electrophysiological procedures are performed. Clinical examination can indeed easily distinguish between the two different prognostic entities, represented by nodal and infra-nodal atrioventricular block. This initial evaluation of the severity of conduction disorders, as soon as the patient arrives at the emergency department or attends a consultation, may be greatly helpful in selecting the most appropriate management of those patients. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Atrioventricular node; Atrioventricular block; Exercise; Carotid sinus
Two-to-one atrioventricular (2/1 AV) block can be nodal or infra-nodal (Hisian or infra-Hisian) in origin. The prognosis of infra-nodal AV block is more severe due to possible progression to unexpected high-degree AV block with haemodynamic instability. This largely depends on whether the type of escape rhythm is low junctional, fascicular, or idioventricular. Electrophysiological investigation of AV conduction, demonstrating atrial (A), Hisian (H) and ventricular (V) potentials, remains the most common diagnostic tool to demonstrate whether AV block is nodal (block between A and H) or related to infra-nodal disease (block between H and V). However, this procedure is invasive, whereas much of the information can be obtained from simple clinical examination and basic electrocardiogram (ECG) interpretation on presentation of the patient. We present the case of a 68-year-old male patient, admitted to our emergency department with a complaint of ⁎ Corresponding author. Clinique Pasteur, Département de Rythmologie, 45 avenue de Lombez, 31076 BP 27617 Toulouse Cedex 3, France. Tel.: +33 5 62 21 16 45; fax: +33 5 62 21 16 41. E-mail address: [email protected] (E. Marijon). 0167-5273/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2007.08.033
episodes of dizziness. He had no prior history of cardiovascular disease and had not taken any medication before admission. Physical examination, chest X-ray and laboratory findings were within normal ranges. An ECG showed 2/1 AV block with no other conduction disturbances (Fig. 1). During left carotid sinus massage of our patient, the AV conduction disorder disappeared, resulting in 1/1 AV conduction (Figs. 2 and 3). However, moderate exercise (just moving in bed) caused dramatic worsening of AV conduction, with 3/1 and 4/ 1 periods. The patient also described his symptoms as being associated with physical activity. After making a diagnosis of 2/1 AV block from the differential diagnosis (premature atrial extrasystole, long QT interval), the site of the conduction disorder (nodal or infranodal) remained the main question. Simple tests have been proposed in order to assess the level of AV block including vagal manoeuvres, exercise, or medication (β blockers, atropine); all of these are reported to have an effect on AV conduction and sinus rhythm [1,2]. Carotid sinus massage or other vagal manoeuvres are expected to worsen AV conduction if the block is nodal, while the AV conduction ratio improves considerably when the pathological changes
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Fig. 1. 12-leads ECG. Sinus rhythm, with only one P from two P waves conducted to the ventricle. QRS complexes remains narrow (100 ms), with normal axis (QRS axis 40°). Normal and constant PR duration (160 ms).
occur at the infra-nodal level. Vagal activation decreases cardiac sinus rate, but has no effect on infra-nodal conduction structures. This results in an apparent improvement in conduction in the case of infra-nodal injury because of the longer PP interval which may then be conducted to the ventricle at a ratio of 1/1. In contrast, exercise or atropine improves AV conduction in cases of nodal conduction disorder.
Rigorous questioning of the patient regarding the conditions leading to occurrence of symptoms and physical examination gave important clues leading to a diagnosis of serious AV conduction disorder immediately after his arrival at the emergency department. Electrophysiological examination confirmed the infra-nodal origin of this conduction disorder, showing that the AV block occurred after a His (H) potential (Fig. 4), and that sinus massage resulted in “pseudo
Fig. 2. Left carotid sinus massage decreased sinus rate and resulted in a “pseudo improvement” of AV conduction, with a 1/1 AV ratio.
E. Marijon et al. / International Journal of Cardiology 132 (2009) e111–e114
e113
Fig. 3. After stopping vagal manoeuvres, sinus frequency and nodal conduction both decrease, with return to a 2/1 ratio AV conduction. Note that PP interval becomes shorter at the end of vagal manoeuvres.
improvement” of AV conduction [3]. A DDD pacemaker was implanted and the patient was discharged free of symptoms. This case demonstrates the value of clinical examination for determining the level of 2/1 AV block. Although infranodal AV blocks, and in particular infra-Hisian blocks, occur frequently in patients with enlarged QRS (partial or total branch block) and/or axial deviation in relation to anterior/ posterior left branch block, narrow QRS complexes in 2/1 AV block may be related to infra-nodal block, particularly Hisian
AV block. In contrast, since the function of the AV node is impaired, the PR interval of the conducted beats is usually prolonged and may increase before blocking, representing a Luciani–Wenckebach period. On the other hand, 2/1 block with PR ≤ 180 ms and no PR variation also suggests an infranodal site of block. As far as a nodal conduction disorders are concerned, it is important to distinguish between functional (secondary to the increase in vagal activity) and organic lesions; in cases of organic disease of the AV node (Lyme's
Fig. 4. Electrophysiological investigations revealed the infra-nodal origin of the AV block: no QRS complex (corresponding to V endocavitary potential — star) after depolarisation of His, confirming the infra-Hisian origin of the AV block.
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disease, myocardial infarction, cardiac surgery, or drug toxicity), improvement of AV node conduction with atropine or exercise may be less apparent. Organic nodal lesions most often have a progressive evolution and have to be treated as infra-nodal lesions. In conclusion, 2/1 AV block may be related to two different prognostic entities. The site of the AV conduction disorder can be assessed immediately by simple physical examination before electrophysiological studies are performed. This initial evaluation of the severity of conduction disorders, as soon as the patient arrives at the emergency department or attends a consultation, may be helpful in selecting the most appropriate management; for example, intensive care unit for patients with evidence of infra-nodal conduction disturbances.
References [1] Leffler CT, Saul JP, Cohen RJ. Rate-related and autonomic effects on atrioventricular conduction assessed through beat-to-beat PR interval and cycle length variability. J Cardiovasc Electrophysiol 1994;5:2–15. [2] Schuchert A, Wagner SM, Frost G, Meinertz T. Moderate exercise induces different autonomic modulations of sinus and AV node. Pacing Clin Electrophysiol 2005;28:196–9. [3] American College of Cardiology/American Heart Association Task Force on Clinical Data Standards (ACC/AHA/HRS Writing Committee to Develop Data Standards on Electrophysiology), Buxton AE, Calkins H, Callans DJ, et al. ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards (ACC/AHA/HRS Writing Committee to Develop Data Standards on Electrophysiology). Circulation 2006;114:2534–70.
Letter to the Editor
Clinical examination should not be forgotten when assessing the level of 2/1 AV block Eloi Marijon ⁎, Nicolas Combes, Serge Boveda, Agustin Bortone, Jamal Najjar, Jean Pierre Donzeau, Jean Paul Albenque Clinique Pasteur, Département de Rythmologie, Toulouse, France Received 10 July 2007; accepted 4 August 2007 Available online 26 November 2007
Abstract The authors underline the importance of carrying out a simple clinical examination to assess the level of two-to-one auriculoventricular block before any invasive electrophysiological procedures are performed. Clinical examination can indeed easily distinguish between the two different prognostic entities, represented by nodal and infra-nodal atrioventricular block. This initial evaluation of the severity of conduction disorders, as soon as the patient arrives at the emergency department or attends a consultation, may be greatly helpful in selecting the most appropriate management of those patients. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Atrioventricular node; Atrioventricular block; Exercise; Carotid sinus
Two-to-one atrioventricular (2/1 AV) block can be nodal or infra-nodal (Hisian or infra-Hisian) in origin. The prognosis of infra-nodal AV block is more severe due to possible progression to unexpected high-degree AV block with haemodynamic instability. This largely depends on whether the type of escape rhythm is low junctional, fascicular, or idioventricular. Electrophysiological investigation of AV conduction, demonstrating atrial (A), Hisian (H) and ventricular (V) potentials, remains the most common diagnostic tool to demonstrate whether AV block is nodal (block between A and H) or related to infra-nodal disease (block between H and V). However, this procedure is invasive, whereas much of the information can be obtained from simple clinical examination and basic electrocardiogram (ECG) interpretation on presentation of the patient. We present the case of a 68-year-old male patient, admitted to our emergency department with a complaint of ⁎ Corresponding author. Clinique Pasteur, Département de Rythmologie, 45 avenue de Lombez, 31076 BP 27617 Toulouse Cedex 3, France. Tel.: +33 5 62 21 16 45; fax: +33 5 62 21 16 41. E-mail address: [email protected] (E. Marijon). 0167-5273/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2007.08.033
episodes of dizziness. He had no prior history of cardiovascular disease and had not taken any medication before admission. Physical examination, chest X-ray and laboratory findings were within normal ranges. An ECG showed 2/1 AV block with no other conduction disturbances (Fig. 1). During left carotid sinus massage of our patient, the AV conduction disorder disappeared, resulting in 1/1 AV conduction (Figs. 2 and 3). However, moderate exercise (just moving in bed) caused dramatic worsening of AV conduction, with 3/1 and 4/ 1 periods. The patient also described his symptoms as being associated with physical activity. After making a diagnosis of 2/1 AV block from the differential diagnosis (premature atrial extrasystole, long QT interval), the site of the conduction disorder (nodal or infranodal) remained the main question. Simple tests have been proposed in order to assess the level of AV block including vagal manoeuvres, exercise, or medication (β blockers, atropine); all of these are reported to have an effect on AV conduction and sinus rhythm [1,2]. Carotid sinus massage or other vagal manoeuvres are expected to worsen AV conduction if the block is nodal, while the AV conduction ratio improves considerably when the pathological changes
e112
E. Marijon et al. / International Journal of Cardiology 132 (2009) e111–e114
Fig. 1. 12-leads ECG. Sinus rhythm, with only one P from two P waves conducted to the ventricle. QRS complexes remains narrow (100 ms), with normal axis (QRS axis 40°). Normal and constant PR duration (160 ms).
occur at the infra-nodal level. Vagal activation decreases cardiac sinus rate, but has no effect on infra-nodal conduction structures. This results in an apparent improvement in conduction in the case of infra-nodal injury because of the longer PP interval which may then be conducted to the ventricle at a ratio of 1/1. In contrast, exercise or atropine improves AV conduction in cases of nodal conduction disorder.
Rigorous questioning of the patient regarding the conditions leading to occurrence of symptoms and physical examination gave important clues leading to a diagnosis of serious AV conduction disorder immediately after his arrival at the emergency department. Electrophysiological examination confirmed the infra-nodal origin of this conduction disorder, showing that the AV block occurred after a His (H) potential (Fig. 4), and that sinus massage resulted in “pseudo
Fig. 2. Left carotid sinus massage decreased sinus rate and resulted in a “pseudo improvement” of AV conduction, with a 1/1 AV ratio.
E. Marijon et al. / International Journal of Cardiology 132 (2009) e111–e114
e113
Fig. 3. After stopping vagal manoeuvres, sinus frequency and nodal conduction both decrease, with return to a 2/1 ratio AV conduction. Note that PP interval becomes shorter at the end of vagal manoeuvres.
improvement” of AV conduction [3]. A DDD pacemaker was implanted and the patient was discharged free of symptoms. This case demonstrates the value of clinical examination for determining the level of 2/1 AV block. Although infranodal AV blocks, and in particular infra-Hisian blocks, occur frequently in patients with enlarged QRS (partial or total branch block) and/or axial deviation in relation to anterior/ posterior left branch block, narrow QRS complexes in 2/1 AV block may be related to infra-nodal block, particularly Hisian
AV block. In contrast, since the function of the AV node is impaired, the PR interval of the conducted beats is usually prolonged and may increase before blocking, representing a Luciani–Wenckebach period. On the other hand, 2/1 block with PR ≤ 180 ms and no PR variation also suggests an infranodal site of block. As far as a nodal conduction disorders are concerned, it is important to distinguish between functional (secondary to the increase in vagal activity) and organic lesions; in cases of organic disease of the AV node (Lyme's
Fig. 4. Electrophysiological investigations revealed the infra-nodal origin of the AV block: no QRS complex (corresponding to V endocavitary potential — star) after depolarisation of His, confirming the infra-Hisian origin of the AV block.
e114
E. Marijon et al. / International Journal of Cardiology 132 (2009) e111–e114
disease, myocardial infarction, cardiac surgery, or drug toxicity), improvement of AV node conduction with atropine or exercise may be less apparent. Organic nodal lesions most often have a progressive evolution and have to be treated as infra-nodal lesions. In conclusion, 2/1 AV block may be related to two different prognostic entities. The site of the AV conduction disorder can be assessed immediately by simple physical examination before electrophysiological studies are performed. This initial evaluation of the severity of conduction disorders, as soon as the patient arrives at the emergency department or attends a consultation, may be helpful in selecting the most appropriate management; for example, intensive care unit for patients with evidence of infra-nodal conduction disturbances.
References [1] Leffler CT, Saul JP, Cohen RJ. Rate-related and autonomic effects on atrioventricular conduction assessed through beat-to-beat PR interval and cycle length variability. J Cardiovasc Electrophysiol 1994;5:2–15. [2] Schuchert A, Wagner SM, Frost G, Meinertz T. Moderate exercise induces different autonomic modulations of sinus and AV node. Pacing Clin Electrophysiol 2005;28:196–9. [3] American College of Cardiology/American Heart Association Task Force on Clinical Data Standards (ACC/AHA/HRS Writing Committee to Develop Data Standards on Electrophysiology), Buxton AE, Calkins H, Callans DJ, et al. ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards (ACC/AHA/HRS Writing Committee to Develop Data Standards on Electrophysiology). Circulation 2006;114:2534–70.