ECG Diagnosis: Ventricular Tachycardia (VT)

Step 1 - What Do the ECGs Show?

ECGs 1 & 2 (WA0006 / WA0005): Active Wide-Complex Tachycardia

• Rate: ~150-180 bpm
• Rhythm: Regular, monomorphic
• QRS: Markedly widened (>160 ms), bizarre morphology
• P waves: Not identifiable - absent or dissociated from QRS
• Axis: Extreme left/northwest axis (positive in I, negative in II and III)
• Precordial leads: Predominantly negative concordance in V1-V6 (no normal RS progression)
• aVR: Tall monophasic R wave

ECGs 3, 4 & 5 (WA0004 / WA0002 / WA0000): Baseline/Sinus Rhythm (Comparator)

• Rate: ~75-80 bpm
• Rhythm: Regular sinus rhythm
• QRS: Normal to mildly widened with normal morphology
• P waves: Visible, preceding each QRS
• ST changes: Possible ST-T abnormalities suggesting underlying structural disease

Step 2 - Systematic Diagnosis Using Standard Criteria

A. Wide-Complex Tachycardia Confirmed

1. Ventricular tachycardia (VT) - most common (~80%)
2. SVT with aberrant conduction (e.g., bundle branch block)
3. SVT with pre-excitation (antidromic AVRT in WPW)

B. Applying the Brugada Criteria (1991) - Step-by-Step Algorithm

YES - In the tachycardia ECGs, V1 through V6 show predominantly monomorphic negative (concordant negative) deflections with no clear RS pattern across all leads. → DIAGNOSIS: VT (Algorithm stops here - highest specificity criterion met)

YES - The QRS duration is >160 ms with a very slow initial deflection. → DIAGNOSIS: VT

YES - No visible P waves preceding QRS; P waves (if present) are dissociated from ventricular activity. → DIAGNOSIS: VT

In V1: dominant R (or monomorphic deflection) inconsistent with typical RBBB/LBBB aberrancy. In V6: deep QS or rS with ratio < 1 rather than typical BBB pattern. → DIAGNOSIS: VT

C. Applying the Braunwald/Wellens Algorithm (Modified)

D. Additional Supportive Criteria (Wellens Criteria, 1978)

• QRS width > 140 ms with RBBB morphology or QRS > 160 ms with LBBB morphology = VT
• Left axis deviation with RBBB pattern = VT
• AV dissociation, fusion beats, capture beats = pathognomonic for VT (though fusion/capture beats may not be clearly visible due to image quality)

E. Classification: Monomorphic VT

• Exit near the right ventricle/septum, OR
• Scar-related reentry (prior inferior/lateral MI most likely in a 90-year-old)

Step 3 - Etiology & Clinical Context

Final Diagnosis

Sustained Monomorphic Ventricular Tachycardia (SMVT)

• Rate: ~150-180 bpm
• Mechanism: Most likely scar-related reentry (prior MI)
• All 4 Brugada steps = positive for VT
• All Wellens/Braunwald morphology criteria = positive for VT
• AV dissociation confirmed (no P waves preceding QRS)
• Machine interpretation disabled by artifact/data quality - clinical override mandatory

Step 4 - How to Confirm & Manage

1. Immediate: Is the patient hemodynamically stable or unstable?
   • Unstable (hypotension, altered consciousness, pulmonary edema) → Synchronized DC cardioversion (100-200 J biphasic)
   • Stable → IV amiodarone (150 mg over 10 min, then 1 mg/min infusion) or IV lidocaine (1-1.5 mg/kg)
2. Do NOT give adenosine - adenosine is for narrow-complex SVT; it is dangerous and ineffective in VT
3. Workup after stabilization:
   • Troponin (acute MI trigger?)
   • Echocardiogram (LV function, wall motion abnormalities)
   • Electrolytes (K+, Mg2+ - hypokalemia and hypomagnesemia lower VT threshold)
   • Coronary angiography if ischemia suspected
4. Long-term:
   • ICD implantation (implantable cardioverter-defibrillator) is guideline-directed if survival is expected >1 year
   • Consider amiodarone for VT suppression
   • Electrophysiology study (EPS) + catheter ablation if recurrent VT

Important note: This analysis is based on ECG interpretation per standard textbook criteria. Clinical decisions must incorporate the full patient presentation (hemodynamics, symptoms, clinical history) and should be made by the treating physician.