Vaughan Williams classification
| Class |
Basic Mechanism |
Comments |
| 1 |
Sodium-channel blockade |
Reduce phase 0 slope and peak of action potential. |
|
1A |
- moderate |
Moderate reduction in phase 0 slope; increase APD; increase ERP. |
|
1B |
- weak |
Small reduction in phase 0 slope; reduce APD; decrease ERP. |
|
1C |
- strong |
Pronounced reduction in phase 0 slope; no effect on APD or ERP. |
| 2 |
|
β-blockers |
Block sympathetic activity; reduce rate and conduction. |
| 3 |
|
K+-channel blockade |
Delay repolarization (phase 3) and thereby increase action potential duration and effective refractory period. |
| 4 |
| Ca++-channel blockade |
Block L-type calcium-channels; most effective at SA and AV nodes; reduce rate and conduction. |
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Content by Dr Íomhar O' Sullivan 08/09/2016. Last review Dr ÍOS 10/06/21.