From the Guidelines
The Brugada criteria for differentiating Ventricular Tachycardia (VT) from Supraventricular Tachycardia (SVT) are based on the examination of the QRS morphology in the precordial leads.
Key Criteria
- Lack of any R-S complexes in the precordial leads (V1-V6) implies VT 1
- R-S interval (onset of R wave to nadir of S wave) >100 ms in any precordial lead implies VT 1
- AV dissociation (with ventricular rate faster than atrial rate) or fusion complexes also implies VT 1
Application
These criteria are essential in the diagnosis and differentiation of wide-complex tachycardias, which can be life-threatening if misdiagnosed.
- The Brugada criteria, along with other ECG algorithms like the Vereckei algorithm, help in distinguishing VT from SVT with aberrant conduction or pre-excitation 1.
- A thorough understanding of these criteria is crucial for accurate diagnosis and appropriate management of patients presenting with wide-complex tachycardias.
Clinical Context
In clinical practice, the application of the Brugada criteria requires careful analysis of the ECG, considering the morphology of the QRS complexes in the precordial leads and the presence of AV dissociation or fusion complexes.
- This approach, combined with clinical judgment and consideration of the patient's symptoms and medical history, is essential for making an accurate diagnosis and providing appropriate treatment.
From the Research
Brugada Criteria for Supraventricular Tachycardia (SVT)
The Brugada criteria are used to distinguish between regular, monomorphic wide QRS complex tachycardias (WCT) caused by supraventricular tachycardia (SVT) and ventricular tachycardia (VT) 2. The criteria include:
- Presence of AV dissociation
- Presence of an initial R wave in lead aVR, which suggests VT
- Morphology of the WCT corresponding to bundle branch or fascicular block
- Estimation of initial (v(i)) and terminal (v(t)) ventricular activation velocity ratio (v(i)/v(t)) by measuring the voltage change on the ECG tracing during the initial 40 ms (v(i)) and the terminal 40 ms (v(t)) of the same bi- or multiphasic QRS complex, where a v(i)/v(t) >1 is suggestive of SVT and a v(i)/v(t) <or=1 is suggestive of VT
Comparison with Other Algorithms
The Brugada criteria have been compared with other algorithms, such as the Vereckei algorithm and the R-wave peak time criterion, and have been found to have a similar diagnostic accuracy 3. However, the Brugada criteria have been found to be less accurate than some newer algorithms, such as the RS/QRS ratio in lead V6, which has been found to be a simple and reliable index for distinguishing VT from SVT in RBBB pattern wide QRS complex tachycardia with a reversed R/S complex in lead V6 4.
Limitations and Variations
The Brugada criteria have been found to have limitations, such as a lower sensitivity and specificity compared to some other algorithms 5, 6. Additionally, the criteria have been modified and simplified, such as the use of only lead aVR for differential diagnosis of wide QRS complex tachycardia 5. The choice of algorithm may depend on the specific clinical situation and the availability of ECG leads.
Key Points
- The Brugada criteria are used to distinguish between SVT and VT
- The criteria include presence of AV dissociation, initial R wave in lead aVR, morphology of the WCT, and estimation of ventricular activation velocity ratio
- The Brugada criteria have been compared with other algorithms and have been found to have similar diagnostic accuracy
- The criteria have limitations and variations, and the choice of algorithm may depend on the specific clinical situation 2, 4, 3, 5, 6