Ventricular Tachycardia
A 66 year old man is complaining of palpitations and chest pain which radiated to his left arm and neck, which lasted 20 minutes, then went away. Paramedics found him in V Tach. His BP was 120/80 and his pulse 120/min. He converted to a narrow-complex rhythm while being given amiodarone, but became nauseated. He returned to V Tach, and his symptoms disappeared. This patient had an implanted defibrillator, which never went off. How do we know this is V Tach?
First, ALWAYS consider any wide-complex tachycardia to be VT unless you have proof that it is not. When symptoms include chest pain, it can be especially dangerous to miss the diagnosis of VT. Remember, some VT can be asymtomatic, even for prolonged periods of time.
ECG signs that this is VT include: QRS is extremely wide (>.14 sec), no P waves associated with the QRS complexes, negative complexes in V4, V5 and V6. In fact, this patient has negative "precordial concordance" - all the chest leads are negative. This is a strong sign of VT. The wide little r wave in V1, greater than .04 sec (one small block) is a strong indicator of VT, as is the delayed nadir of the S waves in V1 through V3 (the slope of the S wave is not steep, indicating a long time to depolarize the ventricles).
For more about V Tach criteria, browse this site and visit the ECG blogs on the Favorites page. It is a favorite topic among ECG experts.
