RBBB, LAHB, Junctional rhythm

RBBB, LAHB, Junctional rhythm


RBBB with LAHB & Junctional rhythmRBBB with LAHB & Junctional rhythm: ECG shows a slow regular rhythm with a ventricular rate of around 43/min. Though there are some baseline artefacts, no definite P waves or fibrillary waves are seen. If the baseline artefacts are considered as fibrillary waves, then it has to be considered as atrial fibrillation with complete heart block and a junctional escape rhythm. If the baseline artefacts are ignored, it becomes a pure junctional rhythm.

Alternate possibility in view of the tall peaked T waves (pink arrows) is an atrial paralysis with sinoventricular conduction in hyperkalemia [1].

Other findings in the ECG are left axis deviation with rS pattern in inferior leads suggesting left anterior hemiblock (LAHB) and qR pattern in V1 and a slurred S in V6 indicating right bundle branch block (RBBB). Delay in septal activation can produce q waves in V1 and V2 in LAHB even without anterior wall myocardial infarction [2]. RBBB and LAHB together constitute a bifascicular block. T wave is inverted in aVL. qR pattern in I and aVL also go with left anterior hemiblock. The difference in pattern between two QRS complexes in V1 is difficult to explain. Minor difference between two QRS complexes in V2 and V3 are also seen.

T wave inversion in V1 and V2 can be secondary repolarization abnormality due to change in depolarization sequence due to right bundle branch block (secondary T wave abnormality). Arrow head T inversion in aVL seems to be a primary repolarization abnormality (primary T wave abnormality), indicating myocardial disease like ischemia or injury [3].

The concept of trifascicular intraventricular conduction was introduced by Rosenbaum MB et al in 1968 [4,5]. Hemiblocks may simulate or conceal the ECG findings of myocardial infarction or ischemia and mask or simulate ventricular hypertrophy [5]. This ECG also looks like right ventricular hypertrophy at one look of V1 and V2. Tall R in aVL may appear like left ventricular hypertrophy.

References

  1. Maradey J, Bhave P. Sinoventricular Conduction in the Setting of Severe Hyperkalemia. JACC Clin Electrophysiol. 2018 May;4(5):701-703.
  2. Horwitz S, Medrano GA. Left anterior hemiblock or inadvertent lead misplacement? Chest. 1976 Mar;69(3):449-50.
  3. Said SA, Bloo R, de Nooijer R, Slootweg A. Cardiac and non-cardiac causes of T-wave inversion in the precordial leads in adult subjects: A Dutch case series and review of the literature. World J Cardiol. 2015 Feb 26;7(2):86-100.
  4. Rosenbaum MB, Elizari MV, Lázzari JO. Los Hemibloqueos. Buenos Aires, Argentina: Paidós; 1968.
  5. Elizari MV, Acunzo RS, Ferreiro M. Hemiblocks revisited. Circulation. 2007 Mar 6;115(9):1154-63.