"J" Day

 

Written By: Brian Smith, DO

 

A patient is brought in by EMS post cardiac arrest:

A 55-year-old man presents to the ED after being found by EMS laying on a park bench in PEA arrest. Chest compressions were initiated and epinephrine was given once, after which ROSC was obtained. He is pale-appearing and cool to touch but does have palpable radial and DP pulses. An ECG is obtained on arrival and shown below.

Question: Which of the following is indicated at this time?

A) TPA

B) Activate code STEMI

C) Calcium Gluconate IV

D) Warm IV Fluids

 
 

Answer: D) Warm IV Fluids

Given our clinical vignette and ECG changes, our patient most likely suffered a cardiac arrest due to hypothermia. Our patient was found to have a core body temperature of 30 C on arrival.

There are many ECG changes that can be seen in hypothermic patients, so let’s review them:


ECG Changes in Hypothermia:

  • Bradyarrythmias

    • Sinus Bradycardia

    • Atrial Fibrillation with Slow Ventricular Response

    • Junctional Bradycardia

    • AV block

  • Prolonged PR, QRS, and/or QT intervals

  • Shivering Artifact

    • Can be seen in mild hypothermia

    • Shivering stops when temperature reaches moderate hypothermia (30-32 C)

  • Osborn (J) Wave

    • Positive deflection at the J point (end of QRS complex) in the precordial and limb leads

    • Reciprocal Negative J point deflection in aVR and V1

Here is an ECG of a hypothermic patient. Can you point out the signs of hypothermia in the ECG?

Source: LITFL https://litfl.com/hypothermia-ecg-library/

Answer: Sinus bradycardia, shivering artifact, Osborn (J) wave



Looking back at our patient’s ECG, there are a few of these changes present:

Here we see Osborn (J) waves - upward deflection of J point in precordial leads - best seen in V4-V6, inferior leads, and lead I (blue asterisks) - with reciprocal negative deflection in aVR (red arrows)

The patient also has QTc prolongation, specifically due to prolonging of the ST segment (similar to hypocalcemia)

Let’s dive a bit deeper into J waves:

The size of the J wave is INVERSELY PROPORTIONAL to temperature.

In the image below we see a decreasing amplitude of the J wave with increasing temperature during the active rewarming process

While J waves are most commonly associated with hypothermia, there are many other causes:

  • Hypercalcemia

  • Acute MI

  • Takotsubo cardiomyopathy

  • Myocarditis

  • Brugada syndrome

  • Left ventricular hypertrophy

  • Benign early repolarization

  • Increased Intracranial pressure

Summary:

  • There are many ECG changes associated with hypothermia

  • The height of the Osborn (J) wave is inversely proportional to temperature

  • While most commonly associated with hypothermia, there are many other causes of Osborn (J) waves

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