Key Points: A QRS duration greater than 120 ms reflects delayed or abnormal ventricular depolarization. A wide QRS may be chronic and benign in context, or it may be the…
A 44-year-old man with severe cardiomyopathy, an LVAD, chronic amiodarone therapy, and an AICD presents with palpitations. His ECG shows a regular wide-complex tachycardia, but the rate is only 135….
A 71-year-old man presents with shortness of breath, and his ECG is initially read as a junctional rhythm. On later review, it is even mistaken for atrial fibrillation. But the…
Key Points: Continuous-flow LVADs can mask cardiovascular collapse. Patients may remain awake during sustained VT or even VF because the pump can provide temporary flow. Treat the rhythm and the…
Key Points: Severe hypothermia causes predictable ECG slowing and conduction delay. Sinus bradycardia, PR/QRS/QT prolongation, and atrial fibrillation with a slow ventricular response are common as core temperature falls. Osborn…
An 81-year-old woman presents with lightheadedness and marked bradycardia. Her ECG shows more P waves than QRS complexes, but the mechanism is not immediately clear. The key question is whether…
Key Points: Do not trust a computer read of “normal” without your own review. Computer interpretation is especially unreliable for subtle or early ischemia, including hyperacute T waves, minimal ST…
A 72-year-old man presents with chest pain and shortness of breath. His ECG shows sinus rhythm with LVH, mild inferior ST elevation, and lateral ST-T abnormalities that some interpret as…
Key Points: Pattern: The South African Flag sign is the combination of ST elevation in I, aVL, and V2 with reciprocal ST depression in III. It is a subtle but…
A 60-year-old woman presents with palpitations and an irregular wide-complex tachycardia. The computer calls atrial fibrillation with a left bundle branch block, but a subtle clue in the precordial leads…
Key Points: Ventricular paced rhythms can mask acute coronary occlusion. Pacing alters depolarization and produces expected secondary ST-T abnormalities, so standard STEMI criteria are unreliable. Appropriate discordance is expected in…
Key Points: Life Savers are the can’t-miss ECGs. These patterns may reflect immediately life-threatening ischemic, electrical, mechanical, obstructive, toxicologic, or metabolic emergencies. This hub is built for rapid action. Use…
Key Points: LBBB does not exclude acute coronary occlusion. LBBB produces abnormal depolarization and expected secondary ST-T changes, which can mask or mimic ischemia. Acute OMI can still be recognized…
A 68-year-old man has syncope, then has a second syncopal episode while lying still on a stretcher during evaluation at an outpatient clinic. He is sent emergently to the ED….
Key Points: Electrical alternans is a beat-to-beat alternation in QRS amplitude, axis, or both. It is classically associated with a large pericardial effusion and may support concern for tamponade, but…
Key Points: Pericardial effusion is the accumulation of fluid in the pericardial sac. ECG may provide clues, but it is not sensitive enough to exclude effusion. Important ECG clues include…
Key Points: Left ventricular hypertrophy (LVH) with strain is one of the most common and dangerous STEMI mimics, particularly in the anterior leads, and is a frequent cause of false-positive…
Key Points: Pericardial tamponade is a hemodynamic diagnosis, not just an ECG diagnosis. ECG may show sinus tachycardia, low-voltage QRS, and sometimes electrical alternans, but none are sensitive enough to…
Key Points: LBBB and ventricular-paced rhythms can hide acute coronary occlusion because abnormal depolarization creates expected secondary ST-T changes. Occlusion MI can still be recognized when those ST changes are…
A 49-year-old man arrives with palpitations and chest discomfort. The monitor shows an irregular, wide-complex tachycardia with varying morphology and rates nearing 250 to 300 bpm. The team debates polymorphic…