Electrolytes

ECG STAT January 6, 2026

Hypocalcemia

Key Points: Prolonged QTc is the hallmark ECG change in hypocalcemia, driven mainly by ST-segment prolongation with relatively normal T-wave shape. Hypocalcemia can increase arrhythmia risk, including TdP, but TdP…

ECG STAT January 6, 2026

Hypercalcemia

Key Points: Shortened QTc interval is the hallmark ECG clue in hypercalcemia, primarily due to a shortened ST segment duration. Hypercalcemia can mimic acute STEMI on ECG (pseudoinfarction pattern due…

ECG STAT November 11, 2025

Himalayan T Waves

Key Points Tall, broad-based T–U fusion that looks like a mountain peak, usually from severe hypokalemia; think high torsades risk until proven otherwise. Hallmark is prolonged repolarization: QT appears long…

ECG STAT September 1, 2025

Hypermagnesemia

Key Points ECG red flags: Bradycardia, PR/QRS/QT prolongation, flattened P, peaked T, → AV block/asystole at higher levels. Neuromuscular: Hyporeflexia → weakness → respiratory depression → coma. Immediate countermeasure (severe/symptomatic):…

ECG STAT September 1, 2025

U Wave: Basics

Key Points Definition and origin: The U wave is a small deflection following the T wave, best seen in V2–V3. It likely reflects late ventricular repolarization or Purkinje repolarization. Normal…

ECG STAT August 14, 2025

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;…

ECG STAT August 14, 2025

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…

ECG STAT June 28, 2025

STEMI vs Severe Hyperkalemia: DDx

Key Points The ECG Chameleon: Severe hyperkalemia can produce ST segment elevations, wide QRS complexes, and conduction delays that closely resemble STEMI or ventricular tachycardia. Early misinterpretation can lead to…

ECG STAT June 6, 2025

Hyperkalemic Periodic Paralysis (Impressive Syndrome)

Key Points What It Is: A rare autosomal dominant sodium channelopathy that leads to episodic muscle weakness or paralysis in the setting of elevated serum potassium. Named after “Impressive,” the…

ECG STAT January 6, 2025

Hypokalemic Periodic Paralysis

Key Points Definition: A rare ion channelopathy that causes sudden, reversible episodes of symmetric flaccid paralysis triggered by low serum potassium. It may be inherited or secondary to thyrotoxicosis or…

ECG STAT December 14, 2024

Hypomagnesemia

Key Points Prolonged QT & PR Intervals significantly increase the risk of torsades de pointes and other arrhythmias. Atrial & Ventricular Ectopy is common; can progress to life-threatening ventricular tachycardia….

ECG STAT November 28, 2024

Hyperkalemia Emergencies

Key Points Severe Hyperkalemia Mimics Several Life-Threatening Conditions: Hyperkalemia can produce a wide range of ECG abnormalities that resemble unstable brady and tachy arrhythmias, STEMI, and can also cause pacemaker…

Weekly Workout March 4, 2019

ECG Basics & Fundamentals: causes of prolonged ST segment

A 54-year-old woman presents to the emergency department with generalized weakness and nausea. She is tachycardic but otherwise has normal vital signs. The following ECG was obtained:

Weekly Workout December 24, 2018

Reverse Wellens Waves: not all biphasic T waves are indicative of ACS!

A 25-year-old woman presents to the emergency department with lightheadedness and palpitations for 1 week. Her symptoms worsened today with a near-syncopal episode. She is thin/frail and dehydrated in appearance….

Weekly Workout October 14, 2018

Differential Diagnoses: a triad of long QT interval, PVCs, & ST segment depression

A 56-year-old woman presents to a busy ED dehydrated with acute gastroenteritis. She is placed in a hallway bed and treated with IV fluids and ondansetron. On reassessment the patient…

Weekly Workout April 10, 2017

STAT ECG Diagnoses: regular wide complex tachycardia (RWCT) after succinylcholine?

A middle-age man presents to the ED with acute hypoxemic respiratory failure from multilobar pneumonia. He is intubated using etomidate and succinylcholine and noted to have a change in rhythm…

Weekly Workout December 11, 2016

Differential Diagnoses: the most likely causes of a prolonged QT interval

A 70-year-old woman presents to the ED with upper abdominal pain and vague paresthesias. The following ECG is obtained:

Weekly Workout February 9, 2015

Differential Diagnoses: long QTc interval

HPI: 32-year-old female with PMHx of hyperthyroidism (on carbimazole) presents with jaundice and intermittent palpitations. She has mild RUQ abdominal pain, but is otherwise well. Vitals: HR~100, BP-130/70, RR-18, afebrile. Exam:…

Weekly Workout February 2, 2015

ECG basics and fundamentals: Prehospital STEMI activations with a review of the literature

50-year-old woman with a PMHx of DM and obesity presents with dizziness and sub-acute back pain. She also reports myalgias and anorexia. She denies any associated chest pain, and is…

Weekly Workout January 12, 2015

Differential Diagnoses: how to use ECG differentials to clinch the diagnosis in sick patients

HPI: 64-year-old male smoker with a Hx of HTN, DM, COPD presents with lightheadedness and chest tightness. He has had flu like symptoms for the past week, that have been…

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