A normal axis means that the overall direction of ventricular depolarisation is normal. This direction can be between -30 degrees (up towards the left shoulder) to +90 degrees (vertically down to the feet).
If the axis is normal, Lead I, Lead II and Lead aVF will all be positive.
Groups of Signs
Variations: QRS axis
This ECG is from a young man who presented shortly after a 45 min episode of palpitations, shortness of breath, chest pressure and presyncope. He was an athlete.
This ECG shows marked sinus bradycardia with AV dissociation by default (not AV block) with junctional escape beats.
This ECG is from an elderly woman who presented with altered mental status on a hot summer day.
This ECG shows sinus tachycardia (124), ST elevation in V1-2 and III and upsloping ST depression in I, aVL and V4-6. POCUS did not show a regional wall motion abnormality. The ST changes resolved with active cooling.
This ECG is from a man in his 40s who presented with intermittent left sided pleuritic chest pain for 3 days.
This ECG shows anterior ST elevation, but there was no anterior wall motion abnormality on echo - there was an inferolateral regional wall motion abnormality instead. Initial troponin was very high. He was found to have a 100% obtuse marginal occlusion. The ECG did not evolve over the next few days, suggesting that it was the patient's baseline ECG.
This ECG is from a woman in her 20s who presented with palpitations for an hour.
This ECG shows a regular narrow complex tachycardia (SVT) with secondary ST segment changes due to the extreme rate (205 bpm).
This ECG is from a man in his 50s who presented with less than an hour of chest pain. This was his initial ECG.
This ECG shows subtle ST elevation in V2 and V3 with a very small amount of ST depression in V4-6. He was monitored and the ECG progressed into a clear STEMI. Catheterisation showed 95% proximal LAD stenosis and occluded 1st diagonal.
This ECG is from a middle aged man who presented with intermittent chest tightness and nausea on walking that resolved with rest. This had happened twice over the past two days. He was likely pain free at the time that this ECG was recorded.
This ECG shows terminal T wave inversion in V2-4, resembling Wellens' waves. There was no wall motion abnormality on echo and troponins were negative (so it was not a true Wellens' syndrome), but a stress echo was markedly positive. Angiogram showed a 95% LAD stenosis and 70% first diagonal stenosis. The cause of the T wave changes was likely ischemia without infarction, ie. unstable angina.
This ECG is from a man in his 50s who had an episode of chest pain and shortness of breath. This ECG was recorded when he was pain free.
This ECG shows sinus bradycardia with T wave inversion in the inferior leads, which was caused by reperfusion of a critical stenosis of the RCA.
This ECG is from a man in his 60s who presented with intermittent shortness of breath and chest pressure over the past few days. This was his initial ECG.
This ECG shows a regular narrow complex tachycardia around 200 bpm, without P waves, with marked ST elevation in inferior leads and ST depression in anterior leads and aVL. The cause was thought to be atrial flutter from newly started flecainide. He also underwent angiography and had stents inserted to the left circumflex and right coronary arteries.
This ECG is from a man in his 60s who presented with intermittent shortness of breath and chest pressure over the past few days. This was his repeat ECG after the rhythm changed.
This ECG shows a sinus tachycardia with ST elevation in inferior leads and ST depression in anterior leads and aVL. He underwent angiography and had stents inserted to the left circumflex and right coronary arteries.
This ECG is from a man in his 60s who presented with intermittent shortness of breath and chest pressure over the past few days. This was his baseline ECG for comparison.
This ECG shows a normal ECG.
Where did they come from?
These ECGs were collected from Free Open Access Medical Education (#FOAMed) blogs, with the permission of their authors. You can find out more about each ECG's source by clicking on it.
Why are they here?
This is an experiment in digital curation. The idea is to collect resources to increase awareness and accessibility. Over time, more ECGs in the collection will be tagged to make it easier to find them and reused in new interactive quizzes.
How can I use these ECGs?
You can use these ECGs for your own learning, teaching or research - as long as you abide by the terms of each ECG's copyright licence as stipulated by the original author.