Differential Diagnosis for Broad Complex Tachycardia
Single Most Likely Diagnosis
- Ventricular Tachycardia (VT): This is the most common cause of broad complex tachycardia, especially in patients with structural heart disease. The broad QRS complex is due to abnormal ventricular activation, often originating from a focus within the ventricle.
Other Likely Diagnoses
- Supraventricular Tachycardia (SVT) with Aberrancy: This occurs when a supraventricular rhythm (like atrial fibrillation or flutter) conducts to the ventricles through an accessory pathway or with bundle branch block, resulting in a broad complex tachycardia.
- Atrial Fibrillation with Wolff-Parkinson-White (WPW) Syndrome: In WPW, an accessory electrical pathway between the atria and ventricles can cause the heart to beat too quickly. Atrial fibrillation in the context of WPW can lead to a broad complex tachycardia due to rapid conduction down the accessory pathway.
Do Not Miss Diagnoses
- Torsades de Pointes: A specific type of VT characterized by a twisting of the QRS complex on the ECG. It can be life-threatening and is often associated with QT interval prolongation.
- Ventricular Fibrillation (VF): Although typically more disorganized than a broad complex tachycardia, VF can sometimes present with a coarse, broad complex rhythm and is immediately life-threatening.
Rare Diagnoses
- Hyperkalemia-induced Arrhythmia: Severe hyperkalemia can cause various arrhythmias, including broad complex tachycardias, due to its effects on cardiac membrane potentials.
- Drug-induced Tachycardia: Certain medications, such as class I anti-arrhythmic drugs, can induce broad complex tachycardias, either by their pro-arrhythmic effects or by inducing abnormal cardiac conduction.
- Cardiac Sarcoidosis or Other Infiltrative Diseases: These conditions can disrupt normal cardiac conduction and lead to various arrhythmias, including broad complex tachycardias, though they are less common causes.