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Mastering ECG Interpretation
· 01.12.2022 · 22:45:51 ··· Donnerstag ⭐ 0 🎬 0
📺 Vithal Panday, M.D.
Heart rate
Normal - 60 to 100
Tachycardic more than 100
Bradycardia less than 60
An ECG can either have a regular or an irregular heart rhythm.
Let's first look at this ECG with a regular heart rhythm. We can calculate the heart rate either by :
1. counting the number of large squares present within one R-R interval
2. divide 300 by the number of large squares
In the second ECG, our patient has an irregular heart rhythm. We can calculate our heart rate by
1.counting the number of complexes on the rhythm strip
2.multiply the number of complexes by 6
When we escribe irregular heart rhythms, they can either be regularly irregular or irregularly irregular
Cardiac Axis
1. describes overall direction of the electrical spread within the heart
In pic 1 , lead 2 has the most positive deflection compared to leads 1 and 3
In pic 2, lead 3 has the most positive deflection and lead 1 should also be negative. Right axis deviation is associated wi h right ventricular hypertrophy.
In pic 3, lead 1 has the most positive deflection and leads 2 and 3 are negative. Left axis deviation is associated with heart conduction abnormalities.
P waves
1. is it present?
2. is the p wave followed by a qrs complex?
3. check duration, direction and shape
4. if absent, is there any atrial activity.
Quick tip, absent p waves and an irregular rhythm may suggest atrial fibrillation.
PR interval
PR interval should be between 3 to 5 small squares. A prolonged or interval suggests the presence of an AV block.
1. first degree heart block - fixed prolonged pr interval
2. second degree heart block - aka mobitz type 1 AV block - typical findings include progressive prolongation of pr interval until the atrial impulse is not conducted and the qrs complex is dropped. AV conduction continues with the next beat and the sequence eventually repeats itself
3. type 2- aka mobitz type 2 AV block - typical findings include a consistent PR interval duration with intermittently dropped QRS complexes due to failure of conduction. The intermittent dropping of the qrs complexes typically follows a repeating cycle of every 3rd or 4th P wave.
4. third degree heart block. No electrical communication between the atria and ventricles due to complete failure of conduction. Findings include the presence of p waves and qrs complexes that have NO association with each other due to the atria and ventricles functioning independently.
Cardiac function is maintained by a junction Al or ventricular pacemaker.
Shortened PR interval
Could mean 1 of two things
1. p wave is originating from somewhere closer to the AV node so the conduction takes less time.
2. the atrial impulse is getting to the ventricle by a faster shortcut instead of conducting slowly across the atrial wall. This is an accessory pathway and can be associated with a delta wave.
QRS complex
- Width - narrow or broad
- Height - small or tall
- Morphology - look at the individual waves of the QRS complex
Delta wave - sign that ventricles are activated earlier tha normal from a point distant to the AV node. Slurred up stroke of the QRS complex. Remember the presence of a delta wave does NOT diagnose WPWS. This requires evidence of tachuarrythmias AND a delta wave.
Q wave - isolated Q can be normal. Pathological Q wave is more than 25 % the size of the R wave which follows Or more than 2 mm in height AND more than 40 ms in width
R AND S waves - look at leads V1-6. Assess progression. Poor progression can be a sign of a previous MI but can also occur in very large people due to poor lead position.
St segment
In healthy individuals, the line should neither be elevated nor depressed.
T wave
-Tall - hyperkalemia and hyperacute STEMI
-Inverted - ischaemia, bundle branch blocks,PE, LVH, hypertrophic cardiomyopathy
- Biphasic - 2 peaks, indicative of ischaemia and hypokalemia
-Flattened - ischaemia or electrolyte imbalance
U wave
Not common finding, can indicate electrolyte imbalance, hypothermia and secondary to antiarrhythmic therapy
· 01.12.2022 · 22:45:51 ··· Donnerstag
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X 0
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B 5
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* · 23.07.2022 · 00:00:00 ···
2 · 25.07.2023 · 22:54:24 ···
L · 01.01.1970 · 01:00:00 ···
C · 16.07.2024 · 22:12:54 ···
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