Core
Results:
Hypokalemia
Key Points: Hypokalemia slows ventricular repolarization and alters the T–U complex before it triggers arrhythmias. Progressive pattern: T-wave flattening → prominent U waves → T–U fusion with apparent QT prolongation;…
Hypokalemia Emergencies
Key Points: Severe hypokalemia can produce dramatic ECG changes that may be mistaken for acute coronary syndromes. It can also precipitate life-threatening arrhythmias, including torsades de pointes and ventricular tachyarrhythmias…
Understanding ECG Artifacts
Key Points Artifacts = non-cardiac signals that distort or obscure true ECG. They come from the patient, leads/equipment, or the environment. Clues to artifact: lacks a physiologic pattern, varies beat-to-beat…
Ischemia & Infarction Interpretation
Key Points: The ECG is the fastest bedside tool for detecting acute coronary occlusion and dynamic ischemia, often before troponin changes and sometimes before classic symptoms. Acute coronary syndromes are…
Fascicular Ventricular Tachycardia (Idiopathic Left Fascicular VT)
Key Points Idiopathic reentrant VT arising within the left Purkinje system, most often the left posterior fascicle. Patients are usually young and lack structural heart disease. Signature ECG: RBBB-like morphology…
Opiate Toxicity
Key Point Opioid overdose causes life-threatening respiratory depression leading to hypoxia, altered mental status, bradycardia, hypotension, and potentially death. While most cardiovascular effects are secondary to hypoxia, methadone toxicity uniquely…
Methamphetamine Toxicity
Key Point Methamphetamine is a powerful sympathomimetic that causes a massive catecholamine surge, it can result in life-threatening cardiovascular and neurologic complications. Toxicity can present with MI, arrhythmias, stroke, hypertensive…
Beta-Blocker and Calcium Channel Blocker Toxicity
Key Point BBs and CCBs are widely prescribed but overdoses can cause life-threatening bradycardia, AV block, hypotension, and shock. Differentiating between them is important, but both require early recognition, aggressive…
Cocaine Toxicity
Key Point Cocaine is a powerful sympathomimetic with profound cardiovascular (CV) effects. Even recreational or first-time use can precipitate life-threatening complications, including myocardial infarction (MI), stroke, arrhythmias, and aortic dissection….
Irregularly Irregular Rhythm: Basics
Key Points: Definition: An irregularly irregular rhythm occurs when the R-R intervals or P-P intervals vary with no consistent pattern, making the rhythm unpredictable and abnormal. Clinical Significance: Identifying an…
Regularly Irregular Rhythm: Basics
Key Points: Definition: A regularly irregular rhythm occurs when the distance between R-R intervals or P-P intervals varies in a consistent, repeating pattern throughout the ECG tracing. Significance: Determining the…
Regular Rhythm: Basics
Key Points: Rhythm Regularity: Regular rhythm is characterized by equal distances between consecutive P waves (P-P intervals) and QRS complexes (R-R intervals). Verify rhythms with calipers—don’t trust the machine interpretation…
Heart Rate & Rhythm Interpretation
Key Points: Treat the patient, not just the number or rhythm. Start with a 10-second stability check. If the rhythm explains hypotension, shock, ischemic chest pain, altered mentation, or severe…
Sinus Arrhythmia
Key Points Definition: Phasic variation in sinus rate with respiration. P-P intervals shorten on inspiration and lengthen on expiration, producing a mild, patterned irregularity. Diagnostic threshold: Difference between the shortest…
Slow Ventricular Tachycardia (VT)
Key Points Definition: Slow ventricular tachycardia is defined as a wide complex tachycardia with a ventricular rate between 100–120 bpm. Distinction: Typical sustained VT usually exceeds 120 bpm. When encountering…
Sinus Arrest
Key Points Definition: Sinus pause/arrest is failure of the sinus node to generate an impulse, producing a transient absence of P waves. On ECG the pause does not equal an…
R-on-T Phenomenon
Key Points Definition: The R on T phenomenon occurs when an ectopic impulse (often a PVC or cardioversion shock) falls on the T wave of the preceding beat. Mechanism: Interrupting…
Multifocal Atrial Tachycardia (MAT)
Key Points Definition: Multifocal Atrial Tachycardia (MAT) is a rare type of irregularly irregular supraventricular tachycardia (SVT) characterized by the presence of at least three or more different P wave…
Right Ventricular STEMI: Criteria & Pitfalls
Key Points: RV involvement accompanies up to ~40% of inferior STEMIs; isolated RV infarction is uncommon but high-impact when missed. Think RV MI when inferior STEMI is present and you…
Toxicologic Emergencies
Key Points: ECG as a Critical Diagnostic Tool: In toxicology, the ECG is often the first and most reliable clue. Early recognition of drug-induced conduction disturbances or arrhythmias can guide…
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