As one progresses into the field internship portion of their Paramedic education, it's vital to remember BLS over ALS. This means, DO NOT forget the fundamentals of ALS care. Anyone can start an IV, but not everyone can stay calm and walk through an assessment. The same goes for 12 lead's. The parameters taught in class should be utilized throughout a career in EMS. By skipping a parameter, the possibility of missing a 1st degree block, STEMI with non-obvious elevation, ST depression and a multitude of other things, may arise.



Both are the same. EKG is the German translation

  1. Is the rhythm regular? (March out P-Waves and R-Waves)

  2. What is the rate? (Utilize the 300,150,100,75 and so on rule)

  3. Are QRS segments narrow? Wide? (.10-.11 is a "partial block" and .12+ is complete)

  4. Is a P-Wave present before each QRS? (Is it prolonged? Upright/Inverted?)

  5. Is the ST-segment elevated? (locate the J point and work off of it)

*be cautious of STEMI mimics  

Normal P-Wave length = .12-.2

Normal QRS length = .08-.12

SA node=Primary pacemaker (60-100 HR) 

AV node=Secondary pacemaker (40-60 HR)

Purkinje/Ventricular=Final pacemaker (20-40 HR)

Junctional rhythms correlate with the AV node

Inverted/buried P-Waves

R-wave's should march out

There's possibility for a wide QRS

Everyone has their own parameters to follow, but by following this method, many mistakes will be avoided.


Indications of a 12 lead

Chest pain

Epigastric pain

Shortness of breath

Syncope or Near-syncope

Pulmonary edema/Cardiogenic shock





Anything you feel may warrant one (GLF?)

As long as a justification is in place, a 12 lead can (and should) be done. Do not worry what your partner thinks (within reason). If one can justify why a 12 lead needs done, then do it.


Lead locations 

V1-4th intercostal space R side midclavicular

V2-4th intercostal space L side midclavicular

v3-Split between V2 and V4

V4-5th intercostal space under the nipple

V5-Split between V4 and V6

V6-5th intercostal space midaxillary (under armpit)

limb leads are called "limb leads" for a reason! Place on limbs for an accurate picture, not on shoulders and abdomen because "it's easier"

Stories may have been told of what a Paramedic should never give/do when dealing with possible cardiac issues. Two of those things I want to touch base on are Zofran and Nitro.


With Zofran (antiemetic), a preceptor may contradict it's administration if a pt. has chest pain. The reason why?  because of the potential to put that pt. into the heart rhythm "Torsades de pointes", or polymorphic VTAC. Even though there's is a chance for this (unknown of the odds), just be aware of any prolonged QT interval. Prolonged QT intervals are normally considered anything longer than .45-.5. The easiest way to describe what may happen is the R-on-T phenomenon. Zofran can cause an issue when repolorization and depolarization happens. If the QT interval is to short, repolarization can occur to quickly. This can result in VTAC. Remember the absolute and relative refractory period? This is when these terms come into play.

With nitro administration, and the presence of an Inferior MI, there is a possibility that the pre-load of the heart can be lost. The pre-load, is essentially the systolic portion of a blood pressure. If this is encountered in the field, no need to panic. Most of the time removing any Nitro Paste, and some fluid will help restore the pressure. Just remember to reassess lung sounds.

​Be cautious of STEMI mimics! 

  • LBBB

  • Left Ventricular Hypertrophy

  • Benign early repolarization

  • Sever hyperkalemia

  • Sever hypothermia

  • Paced rhythms 

  • WPWS (occasionally)

  • Pericarditis

  • Ventricular aneurysm (from prior MI)

  • Prinzmetal agina (coronary spasm)


Always treat anything you're unsure of per protocol. DO NOT risk a license over arrogance

A more advanced way to read each 12 lead.

(Axis deviation, QT interval and so on)