Final answer:
A widened QRS complex on an ECG can be caused by conditions like ventricular tachycardia, bundle branch block, electrolyte imbalances such as hypercalcemia, or ventricular fibrillation. It indicates delayed ventricular depolarization and necessitates further medical evaluation.
Step-by-step explanation:
The causes of a widened QRS complex on an electrocardiogram (ECG) can include several cardiac conditions. A wide QRS complex typically indicates that the ventricles of the heart are taking longer to depolarize. This can be due to ventricular tachycardia, where the shape of the QRS complex is abnormal, or bundle branch block, in which there is a delay or block in the electrical pathways that conduct impulses through the heart's ventricles.
Additionally, electrolyte imbalances, such as hypercalcemia, can affect the ECG. High levels of calcium ions can shorten the QT interval and may also result in a widened T wave. More severe conditions such as ventricular fibrillation, where there is no normal electrical activity, can result in a very irregular and wide QRS complex as well. Less commonly, pharmacological agents or structural heart disease may also lead to abnormalities in the QRS complex.
In any case, a widened QRS complex is a significant finding on an ECG and requires further evaluation by a healthcare professional to determine the underlying cause and appropriate treatment.