A 45 year old male reports to the fire station complaining of chest pain.
- Onset: 15 minutes ago
- Provoke: Nothing makes the pain better or worse
- Quality: A “heavy pressure” in the center of the chest
- Radiation: The pain does not radiate
- Severity: 6/10
- Time: The patient has been experiencing chest pain on and off for the past few days
The patient is obese, anxious, irritated, rude and difficult. He is evasive about his medical history.
He is placed in the back of the ambulance and undressed from the waist up.
His skin is pale and diaphoretic.
Vital signs are assessed.
- RR: 20
- HR: 96
- NIBP: 128/76
- SpO2: 99% on room air
The cardiac monitor is attached.
A 12 lead ECG is obtained.
Sinus rhythm with a rate of 94. There is subtle ST-segment elevation in lead III with a downsloping ST-segment in lead aVL. The wandering baseline in lead V2 is unfortunate because it looks like ST-segment depression may be present.
The patient reluctantly agrees to be transported to the emergency department.
When the QRS complexes are small (in this case less than 5 mm) any amount of ST-segment elevation is significant. This is known as the rule of proportionality which states that repolarization is proportional to depolarization.
To fully appreciate this point look at lead III “stretched” while preserving the ST/QRS ratio.
The paramedic in this case provided oxygen, IV access, aspirin, and sublingual nitroglycerin. The patient’s chest pain was almost entirely resolved by arrival at the hospital.
Sinus rhythm with a rate of 87. The 12-lead ECG is now non-diagnostic.
The patient continued to be difficult in the emergency department and eventually signed out AMA.
Of note, the original prehospital 12 lead ECG never made it into the patient’s chart.