Provided is an ECG image of Atrial fibrillation. Identify the wave pattern and describe it.

Choice A rationale This rhythm occurs when multiple ectopic foci in the atria fire rapidly, leading to a loss of coordinated atrial contraction. The absence of a single depolarization origin means P waves are replaced by chaotic fibrillatory waves. Because the atrioventricular node receives these impulses randomly, the ventricular response is irregularly irregular. This hemodynamic inefficiency often leads to blood stasis in the atria, significantly increasing the risk of thromboembolic events such as stroke. Choice B rationale A regular rhythm characterized by sawtooth waves is indicative of atrial flutter rather than fibrillation. In flutter, a macro-reentrant circuit typically in the right atrium creates a consistent, rapid atrial rate, often around 300 beats per minute. The atrioventricular node usually blocks a portion of these impulses, resulting in a 2 to 1 or 3 to 1 conduction ratio. This maintains a regular ventricular rhythm, unlike the chaotic irregularity seen in fibrillation. Choice C rationale A regular rhythm with a rate between 60 to 100 beats per minute defines a normal sinus rhythm. In this state, the sinoatrial node acts as the primary pacemaker, sending organized electrical impulses through the atria and then to the ventricles. This produces a clear P wave before every QRS complex and a consistent PR interval. Since atrial fibrillation is inherently irregular and lacks P waves, it does not meet these criteria for normalcy. Choice D rationale Wide QRS complexes at a rate exceeding 150 beats per minute are characteristic of ventricular tachycardia. This life-threatening arrhythmia originates in the ventricles, bypassing the normal conduction system and leading to widened QRS durations greater than 0.12 seconds. In contrast, atrial fibrillation usually presents with narrow QRS complexes unless a bundle branch block is present. The primary issue in fibrillation is atrial chaos, not the rapid, wide ventricular firing seen here.