Final answer:
Wide-QRS complex tachycardias are cardiac arrhythmias with a QRS duration over 0.12 seconds, indicating slow ventricular depolarization. They are commonly associated with ventricular tachycardia but can occur in various heart conditions. The QRS complex is vital as it represents ventricular depolarization and impacts cardiac function and systolic blood pressure.
Step-by-step explanation:
Wide-QRS complex tachycardias are a group of cardiac arrhythmias where the QRS complex on an electrocardiogram (ECG) exceeds 0.12 seconds in duration. This broad QRS duration indicates that the ventricles of the heart are depolarizing more slowly than normal. This can occur in various conditions, but it is most commonly associated with ventricular tachycardia, where the abnormal electrical pattern and increased QRS frequency are due to the depolarization originating within the ventricles, thus bypassing the normal conduction pathway. In the context of other ECG abnormalities such as atrial fibrillation the electrical pattern is abnormal prior to the QRS complex, leading to a more chaotic and irregular rhythm.
Furthermore in conditions like a third-degree block, there is a complete disassociation between the atrial and ventricular activities, showing no relation between the P wave and QRS complex, resulting in a potential loss of atrial kick and reduced cardiac efficiency. Because the QRS complex includes the repolarization of the atria any abnormalities within this component of the ECG can significantly impact the overall cardiac function and hemodynamics. Specifically, the QRS complex's role in the depolarization of the ventricles is crucial, as it is followed by systolic blood pressure the peak pressure in the arteries that occurs near the end of the cardiac cycle when the ventricles are contracting.