HPI: A 78-year-old man is brought into the ED by EMS with chest aches, dyspnea, and palpitations. The following prehospital ECG was obtained:
Case ECG

Before watching the video, look closely at this ECG and ask yourself these questions:
- What ECG abnormalities do you notice?
- What is the rhythm?
- Would you activate the cath lab?
ECG findings in Hypothermia
Onset of ECG findings can vary, but resolve with warming
- Early sinus tachycardia
- Shivering artifact
- Bradycardia: sinus, junctional rhythms, slow atrial fibrillation
- J-waves/Osborn waves (positive deflections at the J-point)
- Can cause pseudo-ST segment elevation or depression
- Prolongation of all intervals
- Long QT due to lengthening of the ST segment
- Ventricular fibrillation
- Asystole
Narrow-Complex & Regular Tachycardia Differential
- Sinus Tachycardia
- One P-wave for every QRS
- Upright P-waves in limb leads (I, II, III, aVF) & inverted P-wave in aVR
- Maximum sinus node rate is generally ~ (220 bpm – Age)
- Maximum sinus rate can sometimes exceed this in cases of thyrotoxicosis, sympathomimetic toxicity, well-conditioned athletes, etc.
- Supraventricular Tachycardia (SVT)
- No distinct P-waves. May be hidden or may follow the QRS complex (“retrograde atrial activity”)
- Different types (AVNRT, AVRT, atrial tachycardia, etc.) but generally same treatment and management approach for emergency physicians
- SVT can commonly cause rate dependent ST-segment changes that are benign if it goes away when sinus rhythm is restored
- SVT can also cause electrical alternans that disappears when sinus rhythm is restored
- Atrial flutter with 2:1 Conduction
- 2 atrial beats for every QRS
- Saw tooth pattern, flipping the ECG upside down and paying attention to all 12 leads will help you identify subtle flutter waves
- The most commonly missed atrial tachycardia
- Always consider when rate is 150 ± 20 bpm
To differentiate…always look at what the atrium is doing
(V1 typically best lead to look for atrial activity)
Kudos: Big thanks to Baltimore City Fire/EMS for sharing their cases this week!
Notes: Questions for Amal? Email him at [email protected] or find him on Twitter @amalmattu.