Arrhythmia Classification Four methods: 1: Site of impulse formation–sinus rhythm, atrial rhythms, junctional rhythms. 2: Mechanism–tachy, brady, premature contractions. 3: Conduction disorder–LBBB, RBBB, complete AV block. 4: Seriousness or prognosis–minor, major, fatal. (1) Minor–S tachy, S brady, PAC’s, PNC’s, PAC (<6 / min.) (2) Major–A fib, 1°, 2 °,3° block, PAC, PNC, PVC (>6/min.) (3) […]