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by Nincy Samuel, Western PA student
When reading an EKG, it is vital to have a systematic approach!
- Determine Cardiac Rhythm
- Is the rhythm regular or irregular?
- Identify atrial activity
- Determine P-QRS relationship
- Measure heart rate
- Is the rate normal? (60-100 bpm) bradycardia (<60bpm)? Or tachycardia (>100 bpm)?
How to determine heart rate: count the number of small squares (0.04 secs) between two QRS complexes
|5 small boxes between the 2 QRS complexes
|10 small boxes
|15 small boxes
|20 small boxes
|25 small boxes
|30 small boxes
|35 small boxes
|40 small boxes
- Evaluate P wave morphology
- Inspect P waves in lead II and VI for right and left atrial enlargement
- What is the amplitude? Duration? Direction?
- Assess PR, QRS, and QT interval
- PR interval- normal is 0.12-0.20 seconds. Is it short or prolonged?
- Short PR intervals (less than 0.12 second) indicate that the impulse originated somewhere other than the SA node. This variation is associated with junctional arrhythmias and preexcitation syndromes.
- Prolonged PR intervals (greater than 0.20 second) may represent a conduction delay through the atria or AV junction due to digitalis toxicity or heart block – slowing related to ischemia or conduction tissue disease.
- QRS interval- normal is (less than or equal to 0.10 seconds.
- Make sure to check for a bundle branch block!
- QT interval- what is the duration? Normal QT is less than or equal to one-half of the R-R interval (if HR is normal
- Determine Mean QRS Axis
- Normal is between +90 degrees and -30 degrees
- Is there left or right axis deviation?
- Check leads I and aVF!
- Evaluate QRS Complex, ST and T wave Morphologies
- Is a Q wave present? If it is, what is the distribution?
- Q waves are normal at a width of <0.04 seconds and height of <1/3 of the QRS complex
- Is the QRS amplitude normal? Increased? Or decreased?
- Check for left or right ventricular hypertrophy!
- Is the ST segment elevated, depressed, or isoelectric?
- Check for ischemia, infarction, pericarditis, metabolic/chemical abnormalities!
- Is the T wave upright or inverted?
- Is the amplitude increased or diminished?
- Identify Abnormal ECG Pattern
- Myocardial ischemia and infarction
- Cardiac chamber enlargement and hypertrophy
- Arrhythmias and conduction disturbances
- Miscellaneous patterns (e.g., pericarditis, WPW syndrome, electrolyte imbalances, drug effects)
Pocket Medicine: The Massachusetts General Hospital Handbook of Internal Medicine
Clinical Cardiology Made Ridiculously Simple (Edition 4)
Rutgers PANCE/PANRE Review Course