A 73-year-old male presented with dizziness for 1 year and chest pain for 2 days. His ECG showed left bundle branch block (LBBB) and first-degree atrioventricular block, consistent with possible trifascicular block. Trifascicular block must be confirmed with bundle of His electrogram. The patient has abnormal conduction through one or more divisions of the intraventricular conduction system distal to the bundle of His, presenting as LBBB and first-degree AV block. This suggests involvement of the left and right bundles as well as the AV node, consistent with trifascicular block.

1. ECG OF THE WEEKProf.Dr . G.ELANGOVAN’S unitDr.M.Amudhan

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

6. In this ECGRate – 80/minRhythm – sinus rhythm P wave morphology – normal PR interval – 0.24 sQRS 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 & L3ST eievation in V1 – V3

7. ECGLBBB + First degree AV block POSSIBLE TRIFASCICULAR BLOCK WHICH HAS TO BE CONFIRMED ONLY BYHIS BUNDLE ELECTROGRAM

8. INTRA – VENTRICULAR CONDUCTION DEFECTS Abnormality in conduction thru one or more divisions of intra ventricular conduction system distal to Bundle of His

9. Various conduction defects include:- RBBB LBBB LAFB LPFB Parietal BlockPeri Infarction Block

10. 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 EndocarditisHyperkalemiaCardiac InjuryMassive Pulmonary EmbolismVentricular HypertrophyMyocarditis

11. FASCICLE BLOCK - TYPESUnifascicular Block LAFB LPFB RBBBBifascicular 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 + 1ST or 2nd deg AV Block

12. FASCICULAR BLOCKSLAFBLAD (-30 to -80 )

13. rS in L2,3,aVf