Differential Diagnosis for a 72-year-old man with palpitations and a regular, wide complex tachycardia
- Single most likely diagnosis
- Ventricular Tachycardia (VT): This is the most likely diagnosis given the presentation of a regular, wide complex tachycardia. The presence of fusion beats, which occur when a ventricular ectopic beat coincides with a sinus beat, is highly suggestive of VT.
- Other Likely diagnoses
- Supraventricular Tachycardia (SVT) with Aberrancy: This condition can also present with a wide complex tachycardia if there is aberrant conduction. However, the presence of discordance of the QRS axis in the precordial leads and fusion beats would make VT more likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Torsades de Pointes: A form of polymorphic VT that can be life-threatening. It is characterized by a twisting of the QRS complex on the ECG and can be precipitated by QT interval prolongation.
- Wolff-Parkinson-White (WPW) Syndrome with Atrial Fibrillation: Although less likely given the regularity of the tachycardia, WPW with atrial fibrillation can present with a wide complex tachycardia due to anterograde conduction down the accessory pathway.
- Rare diagnoses
- Bundle Branch Re-entrant Tachycardia: A rare form of VT that involves re-entry within the bundle branches. It typically presents with a wide complex tachycardia and can be associated with structural heart disease.
- Hyperkalemia-induced Tachycardia: Severe hyperkalemia can cause wide complex tachycardia due to its effects on cardiac conduction. However, this would typically be associated with other ECG changes such as peaked T waves and PR segment prolongation.
The options provided in the question support a diagnosis of ventricular tachycardia as follows:
- Fusion beats are a hallmark of VT, indicating that the tachycardia is originating from the ventricles.
- Discordance of the QRS axis in the precordial leads can be seen in VT due to the abnormal ventricular activation pattern.
- Leftward axis can be present in VT, depending on the location of the ventricular focus.
- ST elevation > 5 mm is not typically used to diagnose VT but can be seen in acute myocardial infarction, which can also present with VT. However, this finding is more suggestive of an acute coronary syndrome rather than directly supporting a diagnosis of VT.