Vaughan-Williams Classification

ERP: Effective Refractory Potential

APD: Action Potential Duration

Anti-arrhythmic medications have a variety of different actions and mechanisms, and the Vaughan-Williams classification groups them accordingly.

When this table was initially devised, there were far less anti-arrhythmic medications in comparison to the number available now and our understanding of pharmaceutical mechanisms is, although still incomplete, far greater currently.

The class system is shaky when considering class I and III drugs, given that lots of the drugs in these classifications have similar mechanisms, ergo, could easily fit in the other class category. Even so, whilst the Vaughan-Williams system has limitations, it is still the one through which most physicians base their treatment strategies.

The medications, and their grouping denote the differing efficacies for particular arrhythmias.

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The below table shows the usage of the pharmaceuticals in the Vaughan-Williams classifications, as well as some that it does not feature.

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