Diagnosing Ventricular Tachycardia in 5 easy steps

Here is a simple case of potential ventricular tachycardia(VT) How do you manage this?

A patient has been brought into your resuscitation cubicle with the a complaint of palpitations. His ECG is as follows:
The patient is obviously unstable, so the management decision is easy: ELECTRICITY.

What if the patient is stable with a BP of 138/65 and is sitting up in bed texting on their phone. Many would argue for the same treatment. However, the fact that they are stable does mess with our minds, just a little. We become unsure. We may subconsciously weigh up the risks of sedation and delivering electricity to giving a drug. It sets up a degree of uncertainty.

Here is an example:

A 19 yo woman presents with palpitations and feeling unwell. She has no past history. Her vitals are stable including a BP of 125/60. Her ECG is shown below:

As she is stable, she is treated with IV Amiodarone and proceeds to have a bradycardia arrest and cannot be resuscitated. Why? because this isn’t VT. It’s hyperkalemia. The patient had a K of 9.3 mmol/L

Sometimes we should just sit back and think and watch rather than do.

Caused of Wide Complex Tachycardia(WCT)

• Ventricular Tachycardia (VT)- 80% of cases are VT
• SVT with aberrancy
• Hyperkalaemia
• Na Channel Blockade
• Paced Rhythm

How to Diagnose VT

There are multiple rules that can be used:

1. Brugada Criteria: Rule in VT. Sensitivity 92%, Specificity 65%
2. Vereckei Criteria: Rules in VT: Similar Sensitivity and specificity to Brugada
3. Griffith Criteria: Rules in SVT. Sensitivity 90% Specificity 75%

The problem with these rules is that they are not sensitive enough and they lack consistency across observers. If you sit a group of cardiologists down and ask them to apply them, they will disagree.

My 5 rules for diagnosing VT

1. Is it faster than 120 beats per minute?

   1. For monomorphic VT, the rate must be greater than 120 beats per minute in order for the diagnosis of VT to be made.
   2. The example above of the 19 yo with WCT, who had a bradycardia arrest post amiodarone, demonstrates a rate of 114 beats per minute. It was not VT.

2. Is it wider than 120ms?

   1. This is based on the Brugada algorithm which confirms VT if RS> 100ms. I make it easier by looking at the QRS and asking if it wider than 3 small squares.
   2. Of course beware of the bundle branch block characteristics
   3. Beware also of the very wide complexes. Bizarre wide complexes should make us think of Hyperkalaemia

3. Is there Concordance?

   1. This really asks if all the precordial leads have either a monophonic R or S wave
   2. A simpler way of saying this is, do all the precordial leads predominantly point in one direction?   

4. Is there AV Dissociation?                                                    

5. Is there a characteristic morphology?

   1. Are there Capture Beats or Fusion Beats?
      1. Capture Beats are narrow beats, that represent normal complexes. They confirm VT
      2. Fusion Beats occur when the beat from the AV Node fuses with the beat from the ventricles, resulting in an intermediate-looking beat
   2. Is there a Right Bundle Branch Morphology in V1?
      1. Look for the Rsr pattern ie., the right rabbit’s ear being up.
   3. Is there a Left Bundle Branch Morphology in V1/2?
      1. Look for the notching of the S wave, also known as Josephson’s Sign. It confirms VT
      2. The distance from the QRS onset to the nadir of the S wave being >100ms. It confirms VT.
   4. Is there a QR in V6?
      1. This applies to either RBBB or LBBB patterns    

Below is the Video of my Lecture from this year’s Cardiac Bootcamp.

This video and many others can be viewed by purchasing a subscription to EMCORE Digital.

Peter Kas