Emergency Medical Services (EMS) Agency

ECG OF THE MONTH – MARCH 2020

Case:

Paramedics respond to a 65-year old male with a chief complaint of weakness, nausea, and vomiting. He has a history of hypertension, diabetes, and hyperlipidemia.

032020

 

Rate:                                                 90 bpm

Rhythm:                                            normal sinus rhythm, p waves are noted, before each QRS complex

ST Segment Elevation >1mm
In 2 or more contiguous Leads? 
     Yes, in II, III, aVF, V1, V2

Reciprocal Changes:                        Yes, there are ST depressions in I, aVL, V6

This ECG shows a specific type of inferior ST elevation MI (STEMI) that is concerning for a right-ventricular STEMI. A right-ventricular STEMI is difficult to diagnose on a traditional 12 lead EKG because the only rightward facing ECG lead is V1. In order to diagnose a right-ventricular STEMI, you need to look for the following:

  • consider a right-ventricular STEMI when you see an inferior STEMI
  • ST elevations in lead III will be higher than the ST elevations in lead II
  • Look for ST elevation in V1

Once you suspect a right-ventricular MI, you can obtain a right-sided EKG to confirm the diagnosis.

To obtain a right-sided ECG, right-sided precordial leads are placed on the right anterior chest in a mirror configuration of the left.  To do this, you take V1-V6 and place them on the chest as shown on the picture below.

heart

When the precordial leads are placed on the right side of the chest, they point directly at the right ventricle. Right-sided leads will show ST elevations in a right ventricular

STEMI.  As a shortcut, clinicians oftentimes place lead V4 on the right to view lead V4R.

fig2

Figure 1:  This is a right sided ECG on the same patient.  Note the ST elevation in V4R indicating that the patient is having a right ventricular STEMI.  https://litfl.com/right-ventricular-infarction-ecg-library/

ProTip: the ECG may not be labeled as a right-sided EKG unless if you change the configuration on the ECG. Make sure to label ECG leads (V1R, V2R, V3R, etc.) to avoid confusion.

Right-ventricular STEMIs are preload dependent, predisposing patients to hypotension due to presumed poor right ventricular function.  These patients may present with hypotension, or become hypotensive, which will be fluid responsive.  EMS providers should anticipate this and be prepared to administer IV fluids to increase preload if the patient has signs of poor perfusion.  This patient would be treated per TP-1211, Cardiac Chest Pain, which includes normal saline infusion for patients with poor perfusion.  For patients with STEMI who are normotensive, nitroglycerin is not contraindicated for any STEMI location.  A recent study looking at data in Los Angeles County found no increased risk of hypotension in patients receiving nitroglycerin with angiography confirmed right ventricular STEMIs, suggesting that nitroglycerin can be safely used in the prehospital setting for all patients with suspected cardiac chest pain who have normal blood pressure on paramedic assessment.1  Another study showed no increased risk of hypotension in patients with any inferior STEMI.2  Nitroglycerin can precipitate hypotension in some patients, thus caution should be taken for patients with preload-dependent right ventricular STEMIs particularly if they have borderline blood pressure or an abnormal heart rate.  Be prepared to initiate normal saline if needed.  In this particular patient, one should treat as per TP-1211, Cardiac Chest Pain.  Observe for signs of poor perfusion and manage with IV fluids and push-dose pressors as needed.

References

1 Bosson, N. et al.  Safety and Effectiveness of Field Nitroglycerin in Patients with Suspected ST Elevation Myocardia Infarction.  Prehosp Emer Care.  2018;23(5): 603-611.

2 Robichaud, L. Prehospital nitroglycerin safety in inferior st elevation myocardial infarction. Prehosp Emer Care.  2015.

ECG Image:  https://litfl.com/right-ventricular-infarction-ecg-library/


Author:  Natalia Alvarez, MD