Hello, I'm an expert in cardiology with a focus on electrophysiology. When we talk about a wide QRS complex on an electrocardiogram (ECG), we're referring to the duration of the QRS complex being greater than the normal range, which is typically more than 120 milliseconds in adults. A wide QRS can indicate several different conditions, but it's most commonly associated with:


1. Bundle branch block: This is a delay or block in the electrical conduction system of the heart, which can cause the QRS complex to widen.

2. Ventricular hypertrophy: Enlargement of the ventricles can alter the electrical pathways and result in a wide QRS.

3. Ventricular rhythms: Any rhythm that originates from the ventricles, such as ventricular tachycardia or a ventricular paced rhythm, will have a wide QRS.

4. Certain medications: Some drugs can affect the electrical conduction and prolong the QRS duration.

5. Electrolyte imbalances: Abnormal levels of electrolytes like potassium or calcium can also affect the QRS complex.

It's important to note that a wide QRS is not a diagnosis in itself but rather a sign that prompts further investigation to determine the underlying cause.

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The QRS complex duration is wide (>0.12 seconds or 3 small boxes) in every lead. Causes of a widened QRS complex include right or left BBB, pacemaker, hyperkalemia, ventricular preexcitation as is seen in Wolf-Parkinson-White pattern, and a ventricular rhythm.read more >>