ECG: Trifascicular Block

1. ECG OF THE WEEK Prof.Dr . G.ELANGOVAN’S unit Dr.M.Amudhan

2. 73 year old male presented with c/o giddiness on & off for past 1yr. chest pain past 2 days Past history; not a k/c/o T2DM/SHT/IHD No other significant history O/E pt concious ,oriented, afebrile . no pallor/ icterus /cyanosis/clubbing/LN/pedal edema Vitals; PR 84/min BP 150/90 Cvs : s1 s2 heard. No murmurs. RS: nvbs heard, no added sounds, Other systems also normal.

3. In this ECG Rate – 80/min Rhythm – sinus rhythm P wave morphology – normal PR interval – 0.24 s QRS duration – 0.16 s, QRS axis: - 40 degrees QRS morph. – RR’(M pattern) in V5,V6,aVL & L1 with secondary ST-T Changes Deep S waves in V1-V3 & L2 & L3 ST eievation in V1 – V3

4. ECG LBBB + First degree AV block POSSIBLE TRIFASCICULAR BLOCK WHICH HAS TO BE CONFIRMED ONLY BY HIS BUNDLE ELECTROGRAM

5. INTRA – VENTRICULAR CONDUCTION DEFECTS Abnormality in conduction thru one or more divisions of intra ventricular conduction system distal to Bundle of His Various conduction defects include:- RBBB LBBB LAFB LPFB Parietal Block Peri Infarction Block

6. Causes Of IVCD :- Congenital ( RBBB in normal individuals ) IHD ( AMI / PMI / Coronary atherosclerosis ) Cardiomyopathy ( DCM / HCM ) Infiltrative Lesions ( Tumors / Chagas / Hypothyroidism / Amyloidosis ) Aortic stenosis ( LBBB ) Infective Endocarditis Hyperkalemia Cardiac Injury Massive Pulmonary Embolism Ventricular Hypertrophy Myocarditis

7. FASCICLE BLOCK - TYPES Unifascicular Block LAFB LPFB RBBB Bifascicular Block LBBB RBBB + LAFB RBBB + LPFB Definite Trifascicular Block Alternating BBB RBBB + alternating fascicular block RBBB + Mobitz type 2 second Deg AV Block LBBB + Mobitz type 2 second Deg AV Block Possible Trifascicular Block Complete AV Block with ventricular escape rhythm Any Bifascicular Block + 1 ST or 2 nd deg AV Block

8. FASCICULAR BLOCKS LAFB LAD (-30 to -80 ) rS in L2,3,aVf R in aVL ,L1 Absent q in V5 V6 RS in V5 V6 LPFB RAD ( +120 to + 180 ) rS in aVL , L1, V1 V2 R in L2 L3 aVF Rs in V5 V6 QRS duration Normal Increased QRS voltage Increased VAT Sec ST / T wave changes

9. LBBB 1 st degree:- q in V5 V6 disappears r in V1 V2 disappears 2 nd degree:- initial slurring of R wave in V5 V6 QRS 0.10 – 0.12 sec VAT 0.06 – 0.09 sec Sec ST / T wave changes 3 rd degree :- wide slurred R wave in V5 V6 RR’ / rSR ’ / RSR’ pattern QRS >0.12 sec VAT > 0.09 sec Sec ST / T wave changes

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