EMERGENCY MEDICAL SERVICES-ECG November Issue

header-title-decorationEMERGENCY MEDICAL SERVICES-ECG November Issue

Case:

Paramedics respond to a 57-year-old male with unknown medical history who is unresponsive at home. They first encounter his neighbor, who states that she was visiting to bring him some food that she had prepared for him. She said he had eaten only a few bites before he reported dizziness and diculty breathing, clutching his chest. She suspected that he was having a heart attack and called 9-1-1; he became unresponsive while she was on the phone. The patient has warm, flushed skin.

Vital Signs: BP 65/38, HR 155, RR 32, SpO2: 91% on room air

1. What is your interpretation of this ECG?

ECG courtesy of: Dr. Matthew Hysell

Explanation:

Rate: 155 bpm
Rhythm: Sinus tachycardia
STE Segment Elevation >1mm in 2 or more contiguous leads? No

Ischemic Changes? None

2. Learn more about this ECG pattern

This ECG demonstrates sinus rhythm with extreme tachycardia greater than 150 bpm. Although this rhythm does not have any specific treatment, it is important to recognize that not all narrow complex tachycardia with a rate > 150 bpm is supraventricular tachycardia (SVT). The challenge with a narrow complex, regular tachycardia is distinguishing between a fast sinus tachycardia and SVT. The main distinguishing factor is going to be presence or absence of P-waves. A close look at the ECG shows that there are p waves before every QRS complex. If this were SVT the p waves would not be present prior to the QRS complex. When the rate is very fast it may be dicult to interpret the ECG.

QUESTION: Upon physical exam of the patient, you notice flushed skin, stridor, and wheezing. What is the most likely diagnosis?

  1. Anaphylaxis
  2. Atrial fibrillation with RVR
  3. Panic attack
  4. SVT

Answer: 1. The skin flushing, wheezing, and throat-closing sensation indicate that this is a severe allergic reaction, or anaphylaxis. Although SVT is possible, SVT would not cause skin flushing, wheezing, and a throat closing sensation. It would also be inappropriate to attribute these symptoms to a panic attack — wheezing and skin flushing are not associated with anxiety disorders. Atrial fibrillation with RVR is a tachydysrhythmia that presents with an irregular tachycardia that is usually narrow complex.

3. More about this rhythm

The clinical scenario can also be used to help differentiate the two rhythms. Besides anaphylaxis, severe sepsis is a condition that can cause tachycardia. If the patient appears to have obvious symptoms of another diagnosis, consider that it is sinus

A sudden onset of symptoms without any obvious precipitating factor may clue you in that the diagnosis is SVT, a common presentation would be sudden onset of palpitations, lightheadedness, dyspnea, or anxiety while at rest without an obvious precipitating cause.

 

QUESTION: What is the treatment for an unstable patient with sinus tachycardia?

  1. Amiodarone
  2. Cardioversion
  3. Diphenhydramine
  4. Treat the underlying cause

Explanation: 4. Sinus tachycardia is the body’s attempt to compensate for an underlying problem. There is no specific treatment for sinus tachycardia. Rather we must identify and treat the cause of the tachycardia. Amiodarone is an antiarrhythmic used to treat dysrhythmias; in Los Angeles County EMS protocols it is used to treat refractory pulseless ventricular tachycardia (VT) or ventricular fibrillation (VF). Cardioversion is also used to treat unstable patients with tachydysrhythmias. Diphenhydramine is used to treat hives or itching in the setting of allergic reaction. It does not reverse anaphylaxis and is unlikely to treat sinus tachycardia.

3. ECG Case Follow-up

The patient is correctly assessed as suffering anaphylaxis due to the food exposure in combination with skin flushing and severe hypotension. After two doses of IM epinephrine his vital signs improve to normal levels and his mental status improves to a GCS of 15. He is observed in the ED and admitted to the ICU overnight for airway and blood pressure monitoring. He is discharged the next day with an epinephrine pen prescription and referral for allergy testing.

4. Take Away Points

  • If evaluating for SVT vs. sinus tachycardia, consider the entire clinical picture. Not all narrow rhythms above 150 bpm are SVT. Patient history can help differentiate.
  • The presence of P-waves are the main distinguishing feature between sinus tachycardia and SVT. As the rate increases, it can be harder to see these, even in SVT.
  • Common causes of extreme tachycardia include anaphylaxis and sepsis.

Author: Bijan Arab, DO