In ZSFG intern report yesterday, there was a riveting discussion about a patient with extensive coronary history who presented with syncope and developed a mysterious and unstable tachyarrhythmia, ultimately diagnosed as (surprise!) VT.
First, we reviewed how bedside ultrasound can help us and what we can learn with it. From emergency medicine and point-of-care ultrasound literature, here are the…
Five E’s of Ultrasound:
Effusion: assess for a pericardial effusion
Ejection: qualitative LVEF review
Equality: specifically ventricular equality, referring to the relative size of the RV to the LV Exit: from the heart or assessing the aortic root for aneurysm/dissection
Entrance: to the heart aka the IVC review with respiratory variation
In practice, the effusion and entrance assessment tend to be used the most (…and most reliably). More information on these E’s can be found through this extensive review from the Journal of the Society for Academic Emergency Medicine: http://onlinelibrary.wiley.com/doi/10.1111/acem.12652/full
If, after this teaser, you are yearning for more training in ultrasound, ask your friendly critical care residents/fellows/attendings to go through how they use that Sonosite, ask Nima your burning questions during the June simulation intern half day, and sign up for ultrasound elective available on block months 2nd/3rd year for extra formal teaching!
Now, on to Ventricular Tachycardia…
Nora Goldbadger pearl: The patient in report had a somewhat irregular appearing rhythm on EKG. It was ultimately thought to be, and responded to treatment for, VT. When we asked Nora Goldschlager how this irregular character was possible, she said “I’m not making this up…but there are exit blocks that can cause up to 40ms of delay.” This apparently adds an illusion of irregularity to the VT rhythm strip. BOOM.
Also, if you didn’t click the Goldbadger above, will just leave this here for your viewing pleasure: https://www.youtube.com/watch?v=w-tufNeo06Y
To diagnose VT, we like to use the ole Brugada criteria below. Generally, If any of the criteria is satisfied, VT is the Dx. If none are fulfilled, an SVT is the Dx (AVRT in WPW is an exception).
Here is a more attractive Ventricular Tachycardia stepwise approach. This comes to us from Lekshmi, former Moffitt chief, now pulm fellow.
- Stable or unstable? If unstable (hypotension, chest pain, or altered mental status), proceed with ACLS and assume it’s VT!
- In general, if patient is unstable, assume it’s VT, and if patient is stable, you have more time to figure it out & is more likely to be SVT BUT you can be fooled with slow VT!
- Any risk factors for VT? (e.g. Prior MI, prior cardiac surgery, known scars)? If so, assume it’s VT!
- Do they have a prior EKG with an old LBBB or old RBBB? If the patient is stable AND has an old bundle branch block, more likely to be SVT with aberrancy
- Check for capture or fusion beats: If these are present, it’s VT. these beats have the highest positive predictive value for VT.
- Check for A-V dissociation: A-V dissociation is not required for VT, but is strongly suggestive
- Check for concordance: Look for concordant morphology in leads V1-V6 (i.e. all negative or all positive)
- R wave in aVR present aka “Up in aVR”? This is the Vereckei criteria which is a quick tip for seeing if VT as well!
If you’ve made it this far, patient is stable, and still not sure, now you can bust out Brugada criteria (see above)!
Lastly, want to know how to localize that VT focus. Kevin Duan, also a former Moffitt chief, dropped some knowledge on this before:
Localizing VT focus: some rules of thumb
- Look at Lead I: if negative in lead I, the VT focus is coming from the lateral wall
- Look at inferior leads: if negative, the VT focus is coming from the inferior wall
- Look at aVR: if positive (NW axis), the VT focus is coming from the ventricles and heading towards the base (R shoulder)
- Look at bundle branch pattern: if LBBB, then VT focus is in the RV; if RBBB, then VT focus in the LV
- Look at V5,V6: if negative, the VT focus is coming from the apex
Previous Blog posts: https://ucsfmed.wordpress.com/2016/05/17/cardiology-report-517-dapt-and-ventricular-tachycardia/ https://ucsfmed.wordpress.com/2015/01/22/approach-to-vtach-dx-management-pearls/
Hall et al. The “5Es” of Emergency Physician–performed Focused Cardiac Ultrasound: A Protocol for Rapid Identification of Effusion, Ejection, Equality, Exit, and Entrance. Journal of the Society of Academic Em Med. 2015: 22(5), 1553-2712. http://dx.doi.org/10.1111/acem.12652.
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