LOADING AWESOME
LOADING AWESOME
ANTIARRHYTHMIC DRUGS
www.propofology.com
Dr. David Lyness
@Gas_Craic
THE VAUGHAN-WILLIAMS CLASSIFICATION AND CARDIAC ACTION POTENTIAL
MAGNESIUM
Mg acts as a physiologic Calcium Channel inhibitor by slowing slow
L-Type Calcium channel during PHASE 2. This reduces further Ca release by the Sarcoplasmic Reticulum which leads to reduced automaticity, contractility and conductivity through cardiac tissue, including the AVN.
Classes
I- Sodium Channel Blockers
II- Beta Blockers
III- K channel blockers
IV - Calcium Channel Blockers
Think of Prince William - SOon to Be King of the Castle
I II III IV
LOADING AWESOME
Rapid utilisation of drugs is often necessary to control arrhythmias and prevent
progression of negative sequelae. There are FIVE main classes of drugs that achieve this.
Worth a mention
Whilst amiodarone is a class 3 potassium blocker - this is late at around 8h post dose and primary mechanism of rapid control is Na, K and Ca blockade.
Magnesium prolongs phase two of the cardiac action potential by acting as a Calcium Channel Blocker - so really has Class IV effects - but is class V.
I - Ventricular Arrhythmias, PAF, WPW
II - Prevent occurrence of tachyarrythmias, decrease MI mortality
III - WPW, VT's and AF (amiodarone has a few class actions)
IV - Prevents re-occurance of SVT's, reduces ventricular rate in AF
V - SV arrythymias, good in heart failure with AF. Not for ventricular arrhythmias.
MgSo4 is used in Torsades De Pointes.
