An EKG of a 57-year-old male with diabetes showed a first-degree AV block, right bundle branch block, and left anterior fascicular block consistent with a trifascicular block. Trifascicular block indicates advanced heart disease but the risk of sudden progression to complete heart block is not great. The patient is scheduled for a low risk surgery given he is asymptomatic for the trifascicular block and has intermediate to high clinical predictors due to his diabetes.

1. Trifascicular Block
Candice Reyes
Cardiology
July 17, 2009

2. Subjective
• 57 y/o male transferred to RLAH for eval
and treatment of R 3rd met plantar ulcer
and gangrene of R 3rd toe
• Pt has no h/o cardiac dz, he has no
cardiac sx
• PMHx: DM x2yrs w/o tx

3. Objective
• Vitals: BP 128/75 P 86 T99 O2Sat 99% Wt
95.6 F.S. 286
• CV: decr heart tones w/RRR S1S2 w/o
murmur
• Resp: LCTA B/L
• Extremities: RLE has erythema and 2+
pitting edema

5. EKG Discussion
• Prolongation of PR interval – 1st Degree
AV Block
• RBBB
• LAFB
• Findings suggest trifascicular block

6. Trifascicular Block
• Conduction blocks in all 3 fascicles
– Can be permanent or transient
• Criteria:
– 1) RBB and LASF w/1st degree AV block
– 2) RBB and LPIF w/1st degree AV block
– 3) LBB w/1st degree AV block or
– 4) Alternating RBBB and LBBB

7. Trifascicular Block
• Trifascicular, along w/bifascicular, blocks
indicate advanced heart dz
• BUT long-term follow-up studies of
ambulatory patients indicate that risk of
sudden progression to complete heart
block and sudden death d/t ventricular
asystole is not great
Bolton Edmund, "Chapter 28. Disturbances of Cardiac Rhythm and Conduction" (Chapter). Tintinalli
JE, Kelen GD, Stapczynski JS, Ma OJ, Cline DM: Tintinalli's Emergency Medicine: A
Comprehensive Study Guide, 6e: http://www.accessmedicine.com/content.aspx?aID=587596.

8. Assessment and Plan
• Dr. Quesada’s Assessment and Plan: These
findings suggest a trifascicular block.
Progression of chronic bifasicular or trifascicular
block to complete heart block is infrequent. This
pt is asx and was very active prior to
hospitalization
• Per guidelines, the pt has intermediate to high
clinical predictors (DM asx trifascicular block)
and is scheduled for a low risk surgical
procedure