A multi-lead diagnostic electrocardiogram (ECG) rhythm strip illustrating complex cardiac arrhythmias. The baseline rhythm shows atrial fibrillation, characterized by an irregularly irregular ventricular rate and the absence of discernible, consistent P waves. Superimposed on this baseline is a run of nonsustained ventricular tachycardia (NSVT). The wide-complex tachycardia morphology demonstrates a left bundle branch block (LBBB) pattern, evident by the predominantly negative QRS deflection in leads V1 through V3 and a late QRS transition occurring around lead V4. The inferior leads (II, III, and aVF) show a positive QRS axis, indicating an inferior axis. These visual findings—LBBB morphology with an inferior axis and late transition—are clinically suggestive of an arrhythmia originating from the right ventricular outflow tract (RVOT). The T waves exhibit secondary repolarization changes, including inversions in leads with positive QRS complexes. This ECG serves as an educational example of identifying ventricular tachycardia origin sites based on QRS morphology and axis transition in the precordial leads.

A 12-lead baseline electrocardiogram (ECG) recorded at 25 mm/s and 10 mm/mV, demonstrating complex cardiac conduction abnormalities. The tracing shows a rapid, irregular atrial arrhythmia, likely atrial fibrillation or high-frequency atrial tachycardia, with an atrial rate of approximately 180 beats per minute. Distinct P waves are absent, replaced by fibrillatory waves visible in the baseline, particularly in lead V1. Concurrent with this is a complete (third-degree) atrioventricular (AV) block, evidenced by the total dissociation between atrial activity and ventricular response. The ventricles are driven by a junctional escape rhythm, resulting in a slow, regular ventricular rate of approximately 43 beats per minute. The QRS complexes are relatively narrow (approximately 90 ms), consistent with a supra-Hisian escape focus. The tracing includes limb leads (I, II, III, aVR, aVL, aVF) and precordial leads (V1-V6), with a continuous lead II rhythm strip at the bottom. This visual record is characteristic of advanced conduction system disease, often associated with LMNA-related cardiomyopathies or other structural heart diseases.

This composite educational image illustrates the management of refractory tachycardia-induced cardiomyopathy. Panel A presents a 12-lead electrocardiogram (ECG) showing atrial fibrillation with a rapid ventricular response (tachyarrhythmia). The tracing is characterized by absent P waves, irregular R-R intervals, and narrow QRS complexes at a rate of approximately 175 bpm. Panel B displays a follow-up ECG after an 'ablate and pace' intervention, specifically showing a more controlled rhythm resulting from atrioventricular (AV) node ablation and subsequent His bundle pacing (HBP). Panel C is a fluoroscopic angiogram in a post-procedural state, depicting the anatomical placement of cardiac pacing leads. Key landmarks include the atrial lead positioned superiorly, the HBP lead situated in the region of the His bundle, and a backup right ventricular (RV) lead. A large, radiopaque extracorporeal membrane oxygenation (ECMO) cannula is visible in the background, crossing the cardiac silhouette. This content demonstrates advanced electrophysiological strategies and mechanical circulatory support in the context of cardiogenic shock and refractory arrhythmia.