Here is the link to the show notes and podcast of Ep 112 Tachydysrhythmias with Amal Mattu and Paul Dorion of July, 2018.
The podcast is worth listening to more than once (for me, a lot more than once.)
And here are some excerpt reminders for myself:
Ventricular Tachycardia (VT) vs SVT with aberrancy: Assume VT
Wide & regular = ventricular tachycardia until proven otherwise. Clinical stability does not differentiate between VT and SVT with aberrancy.
As per ACLS guidelines, If any tachydysrhythmia presents as unstable, the treatment of choice is synchronized electrical cardioversion.
For wide and irregular tachycardia consider other diagnoses (especially when standard treatments are not effective at restoring normal sinus rhythm) such as:
- Hyperkalemia (HR usually < 120 bpm)
- Sodium channel blocker toxicity (often very wide QRS > 200 ms)
- Accelerated Idioventricular Rhythm (AIVR). This is a reperfusion rhythm often seen post-lytics for STEMI; Think of “slow VT”. The treatment is observation, not medication. [And one of the speakers states that this rhythm can also occur in patients in whom the infarct related artery has spontaneously reperfused.]
Pitfall: Mistaking AIVR (post-lytics for STEMI) for VT and treating with lidocaine may cause cardiovascular collapse.
VT is not a single entity
There are 4 types of VT that EM providers need to be aware of:
1. Scar mediated monomorphic VT – the classic VT we see in older patients with a cardiac history
->Rx: procainamide, as per the PROCAMIO study.
2. Polymorphic VT – usually related to a cardiac ischemic event
->Rx: amiodarone
3. Exercise induced non-sustained monomorphic VT – in young patients (e.g. 20’s)
->Rx: no ED treatment required; outpatient beta blockers
4. Catecholaminergic Polymorphic VT (CPVT): Heritable VT in young patients (teens/20’s) presenting as polymorphic or bidirectional with a LBBB pattern and inferior axis.
->Rx: IV beta blocker, AVOID amio and procainamide
Management of Stable Ventricular Tachycardia
The 2016 PROCAMIO RCT trial compared IV procainamide and amiodarone for the treatment of acute but stable sustained monomorphic VT. Procainamide was associated with less major cardiac adverse events and a higher proportion of tachycardia termination within 40 minutes. Procainamide is currently considered to be the first line medication for sustained monomorphic VT in stable patients.
Indications for amiodarone in VT
While procainamide is currently considered to be the first line medication for stable sustained VT, there remain three important indications for amiodarone in the setting of VT:
1. Polymorphic VT related to cardiac ischemia
2. ICD patient with VT above detect rate (usually >175 bpm)
3. VT in the cardiac arrest patient
VT in the ICD patient
VT below detect (usually <175 bpm)
VT is too slow for ICD to recognize. Treat as you would any VT.
VT above detect (usually >175 bpm)
Recurrent episodes of VT. Treatment involves prevention, which is usually a combination of IV amiodarone, beta blockade and sedation. Consider causes such as ICD malfunction, electrolyte imbalance and severe CHF.
Magnet? If an ICD patient is not in VT but their ICD is delivering shocks, place a magnet on the ICD to put it into VVI mode (pacing preserved, shocking disabled).
Atrial fibrillation with Wolff Parkinson White (WPW)
- Irregularly irregular tachycardia
- Changing QRS morphologies (as opposed to AF with a bundle branch block, which will be monomorphic)
- Rate 250-300 bpm
WPW with atrial fibrillation – Avoid all AV nodal blockers including amiodarone! From Life in the Fast Lane blog.
Avoid all AV nodal blockers including amiodarone. Blocking the AV node may precipitate a fatal ventricular tachydysrhythmia as conduction will preferentially travel through the accessory pathway. Treat with electrical cardioversion or procainamide.
Resources:
(1) Ep 112 Tachydysrhythmias with Amal Mattu and Paul Dorion [Link is to the show notes and podcast] [Link To PDF Show Notes]
