Prolonged QRS complex

An intraventricular conduction delay on ECG, defined by QRS duration exceeding 100-120 ms, indicating impaired or slowed ventricular depolarization. Commonly due to bundle branch block, ventricular tachycardia, hyperkalemia, ventricular hypertrophy, medications (tricyclic antidepressants, sodium-channel blockers), cardiac amyloidosis, cardiac fibrosis, and pacemaker rhythm.