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Interatrial Block (IAB)

ITERATRIAL BLOCK

anwerghanijaber
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Interatrial Block (IAB)

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  1. ANWER GHANI FIBMS IRAQ Interatrial Block (IAB)

  2. . It has been considered that an interatrial block exists when there is a delay of conduction in some part of the Bachmann’s bundle zone.

  3. . • The interatrial blocks are the most frequent and well-known blocks at atrial level.

  4. . • Partial IAB (P-IAB) : P wave duration that equals or exceeds 120 milliseconds and a bimodal morphology, especially in leads I, II, VL or inferior leads.

  5. . • advanced interatrial block (A-IAB): P wave morphology ± in II, III, and VF with duration ≥120 ms.

  6. . • The prolonged P wave duration (P-wave duration ≥120 milliseconds) may be present in the elderly but can also be a consequence of acute illness, such as pericarditis or acute myocardial infarction.

  7. . The combination of LAE with advanced interatrial block (A-IAB) is very common but isolated cases of A-IAB may be seen.

  8. . • Cutting the Bachmann’s bundle at either the right or left atrial side results in a typical ECG pattern with wide P wave with biphasic morphology in inferior leads.

  9. . • The interatrial blocks may be of first (partial), second (transient interatrial block is part of atrial aberrancy), or third degree (advanced).

  10. .First-degree (Partial) Interatrial Block • -The electrical impulse is conducted from the right to the LA through the normal propagation route but with a delay. • -The ECG shows that a P wave of 120 milliseconds or more, usually bimodal, is especially visible in leads I, II, or III.

  11. Second-degree Interatrial Block Interatrial block occurs transiently on a beatby- beat basis or may be recorded momentarily. The morphology of the P wave may change in the same recording from interatrial block pattern (first or third degree) to normal pattern, usually transiently in relation to the preceding premature beats. These changes may be considered as atrial aberrancy. Atrial aberrancy may also present a transient bizarre P wave without the morphology of interatrial block. In these cases, the location of the block is usually the right atrium.

  12. Third-degree (advanced) Interatrial Block • The electrical impulse is blocked especially in the upper and middle part of the interatrial septum, in the Bachmann’s bundle zone, and/or in the upper part of LA. • Retrograde left atrial activation occurs mainly via muscular connections in the vicinity of coronary sinus. • In rare occasions, the right atrium and LA can demonstrate dissociated electrical activity.

  13. Third-degree (advanced) Interatrial Block • The ECG shows that • (a) P wave duration of 120 milliseconds or more. • (b) the morphology of P wave is usually biphasic [±] in leads II, III, and VF ( and also often in V1 to V3) • The electrophysiological mechanism underlying this ECG pattern has been explained using deductive ECG-VCG data.

  14. Third-degree (advanced) Interatrial Block • In dogs, the same biphasic morphology appears after cutting the Bachmann’s bundle at the right and left sides of the septum. • Atrial fibrosis is considered the anatomic substrate of A-IAB, which does not necessarily mean that the LA is enlarged. • P wave (biphasic in inferior leads) that pinpoints that there is a retrograde activation of the LA. • This type of block is very frequently accompanied by paroxysmal atrial arrhythmia.

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  16. Inter-Atrial Block degrees • 1st d: pIAB: prolonged P-wave duration>120 ms. • 2nd d: tIAB: transient IAB, ( a, p) • 3rd d: aIAB : prolonged P-wave duration>120ms + biphasic P-wave morphology. • - Bayés syndrome: The association of A-IAB and AF.

  17. . The prevalence of partial (P) and advanced A–IAB is rare before the age of 50. The prevalence is much higher with advancing age. In patients with heart failure a prevalence of A-IAB of 10 %.

  18. . • The advanced IAB group presented a higher incidence of atrial flutter/fibrillation during a 30-month follow-up compared with partial IAB. • At one year of follow-up, the incidence of arrhythmias was 80 % and 20 % of AIAB and PIAB respectively. • The prevalence of frequent premature atrial contractions (more than 60/h by Holter) was much more frequent in advanced (75 %) than in partial (25 %) IAB.

  19. Bayés syndrome • The association of A-IAB and AF has been called Bayés syndrome.

  20. . • The strong relationship between advanced IAB and atrial flutter/ fibrillation suggests the possible role of preventing atrial arrhythmias using antiarrhythmic drugs. • A small comparative trial of patients with advanced IAB received either an antiarrhythmic drug or a placebo. • A significant reduction of AF recurrences was observed at follow-up in the group receiving prophylactic antiarrhythmic medication.

  21. BAYÉS SYNDROME Bayés syndrome is a new clinical entity, characterized by the association of advanced interatrial block (IAB) on surface electrocardiogram with atrial fibrillation (AF) and other atrial arrhythmias. This syndrome is associated with an increased risk of stroke, dementia, and mortality. Advanced IAB is diagnosed by the presence of a P-wave ≥ 120ms with biphasic morphology (±) in inferior leads. The cause of IAB is complete Bachmann bundle blockade, leading to retrograde depolarization of the left atrium from areas near the atrioventricular junction. The anatomic substrate of advanced IAB is fibrotic atrial cardiomyopathy. Dyssynchrony induced by advanced IAB is a trigger and maintenance mechanism of AF. This alteration of the atrial architecture produces atrial remodeling, blood stasis and hypercoagulability, triggering the thrombogenic cascade. The presence of advanced IAB, even in patients without documented atrial arrhythmias, has also been associated with AF, stroke, dementia, and mortality. However, in these patients, there is no evidence to support the use of anticoagulation. What every clinician should know about Bayés syndrome Síndrome de Bayés. Lo que todo clínico debe conocer Antoni Bayés de Lunaa, Manuel Martínez-Sellésb, , Antoni Bayés-Genísc, Roberto Elosuad, Adrián Baranchuke Revista Española de Cardiología .2020.04.026

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  23. BAYÉS SYNDROME In 1988, Bayés de Luna et al.1 reported that patients with advanced interatrial block (IAB) presented with supraventricular arrhythmia more often than patients with partial IAB. However, until a consensus article was published on IAB in 2012,2 only a few authors had shown interest in the subject, mainly the groups led by Spodick,3 García-Cosío,4 and Platonov,5 as well as our own group.6,7 Since this consensus article was published, there has been growing interest, and Conde and Baranchuk8 named this combination “Bayés syndrome,” a term quickly accepted by the scientific community. What every clinician should know about Bayés syndrome Antoni Bayés de Lunaa, Manuel Martínez-Sellésb, Antoni Bayés-Genísc, Roberto Elosuad, Adrián Baranchuke Revista Española de Cardiología .2020.04.026

  24. THANKS The reference: Antoni Bayés de Luna,Albert Massó-van Roessel,Luis Alberto Escobar Robledo; The Diagnosis and Clinical Implications of Interatrial Block.European Cardiology Review 2015;10(1):54–9

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