Hello, I'm an expert in cardiology with a focus on electrophysiology. I'd be happy to explain what a widened QRS is.

A widened QRS complex on an electrocardiogram (ECG or EKG) is a diagnostic finding that indicates the ventricular depolarization phase is taking longer than normal. Normally, the QRS complex is between 0.06 to 0.10 seconds in duration, and it represents the electrical activity of the ventricles contracting to pump blood out of the heart. When the QRS complex is wider than this normal range, it can suggest several conditions:


1. Bundle branch block: This is a common cause of a widened QRS and occurs when there is a delay in the electrical conduction through the left or right bundle branches of the heart.

2. Ventricular hypertrophy: Enlargement of the ventricles can also lead to a wider QRS as the electrical impulse takes longer to travel through the thicker muscle.

3. Myocardial infarction (heart attack): Damage to the heart muscle can alter the normal conduction pathways, resulting in a wider QRS.

4. Certain medications: Some drugs, like tricyclic antidepressants or class I antiarrhythmics, can affect the duration of the QRS complex.

5. Infective endocarditis: Inflammation of the heart valves can also cause changes in the QRS complex.

6. Ventricular rhythms: Any rhythm that originates in the ventricles, such as ventricular tachycardia or ventricular fibrillation, will have a wide QRS because it's not following the normal conduction system.

It's important to note that a widened QRS is a nonspecific finding and requires further evaluation to determine the underlying cause. A comprehensive medical history, physical examination, and additional diagnostic tests are often necessary to make a definitive diagnosis.

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Definition of QRS widening. QRS duration > 100 ms in the presence of a supraventricular rhythm. Most commonly due to bundle branch block or left ventricular hypertrophy.read more >>