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Common findings. Sinus rhythm (which is the normal rhythm) has the following characteristics: (1) heart rate 50–100 beats per minute; (2) P-wave precedes every QRS complex; (3) the P-wave is positive in lead II and (4) the PR interval is constant.
- Rhythm. Assess ventricular (RR intervals) and atrial (PP intervals) rate and rhythm: Is ventricular rhythm regular? What is the ventricular rate (beats/min)?
- P-wave morphology and PR interval. Assess P-wave morphology and PR interval. P-wave is always positive in lead II (actually always positive in leads II, III and aVF).
- QRS complex. Assess QRS duration, amplitudes, Q-waves, R-wave progression and axis. QRS duration must be <0,12 s (normally 0,07-0,10 s). There must be at least one limb lead with R-wave amplitude >5 mm and at least one chest (precordial) lead with R-wave amplitude >10 mm; otherwise, there is low voltage.
- ST segment. Assess the ST segment (morphology, depression, elevation) The ST segment should be flat and isoelectric (at level with the baseline). It may be slightly upsloping at the transition with the T-wave.
- Confirm Details
- Heart Rate
- Heart Rhythm
- Cardiac Axis
- P Waves
- QRS Complex
- St Segment
- U Waves
- Document Your Interpretation
- Want to Learn More About Ecgs?
Before beginning ECG interpretation, you should check the following details: 1. Confirm the name and date of birthof the patient matches the details on the ECG. 2. Check the date and timethat the ECG was performed. 3. Check the calibration of the ECG (usually 25mm/s and 10mm/1mV).
What is a normal adult heart rate?
1. Normal: 60-100 bpm 2. Tachycardia:>100 bpm 3. Bradycardia:<60 bpm
Regular heart rhythm
If a patient has a regular heart rhythm, their heart rate can be calculated using the following method: 1. Count the number of large squares present within one R-R interval. 2. Divide 300 by this number to calculate heart rate.
Irregular heart rhythm
If a patient’s heart rhythm is irregular, the first heart rate calculation method doesn’t work (as the R-R interval differs significantly throughout the ECG). As a result, you need to apply a different method: 1. Count the number of complexes on the rhythm strip (each rhythm strip is typically 10 seconds long). 2. Multiply the number of complexes by 6 (giving you the average number of complexes in 1 minute).
A patient’s heart rhythm can be regular or irregular. Irregular rhythms can be either: 1. Regularly irregular(i.e. a recurrent pattern of irregularity) 2. Irregularly irregular(i.e. completely disorganised) Mark out several consecutive R-R intervals on a piece of paper, then move them along the rhythm strip to check if the subsequent intervals are ...
Cardiac axis describes the overall direction of electrical spreadwithin the heart. In a healthy individual, the axis should spread from 11 o’clock to 5 o’clock. To determine the cardiac axis, you must look at leads I, II and III. Read our cardiac axis guideto learn more.
The next step is to look at the P wavesand answer the following questions: 1. Are P waves present? 2. If so, is each P wave followed by a QRS complex? 3. Do the P waves look normal? – check duration, direction and shape 4. If P waves are absent, is there any atrial activity? 1. Sawtooth baseline → flutter waves 2. Chaotic baseline → fibrillation wa...
When assessing a QRS complex, you need to pay attention to the following characteristics: 1. Width 2. Height 3. Morphology
The ST segment is the part of the ECG between the end of the S wave and the start of the T wave. In a healthy individual, it should be an isoelectric line (neither elevated nor depressed). Abnormalities of the ST segment should be investigated to rule out pathology.
U waves are not a commonfinding. The U wave is a > 0.5mm deflection after the T wave best seen in V2 or V3. These become larger the slower the bradycardia – classically U waves are seen in various electrolyte imbalances, hypothermia and secondary to antiarrhythmic therapy(such as digoxin, procainamide or amiodarone).
You should document your interpretation of the ECG in the patient’s notes (check out our guide to documenting an ECG).
We have several other articles relevant to ECGs: 1. Understanding an ECG: a guide to understanding the underlying concepts of ECGs 2. Cardiac axis explained: a simple guide to the cardiac axis 3. How to record a 12-lead ECG: an OSCE guide to recording a 12-lead ECG 4. How to document an ECG: a guide to documenting your ECG interpretation in the not...
- Dr Matthew Jackson
ECG devices market valuation from diagnostic ECG machines reached USD 4 billion in 2022. The growing demand for diagnostic ECG machines, including stress ECG and resting ECG can be attributed to the increasing number of people suffering from chronic illnesses.
- USD 10.5 Billion
- 2023 to 2032
- 2022
- 2018 to 2022
- Global market for electrocardiogram devices size was worth more than USD 7 billion in 2022 and is projected to record a 4% CAGR from 2023-2032. Rea...
- Non-portable ECG devices is projected to exhibit over 3.5% CAGR between 2023-2032 due to increasing use in the treatment of atrial flutter and atri...
- Asia Pacific electrocardiogram devices market size is anticipated to expand at over 4% CAGR from 2023-2032 owing to the rising prevalence of chroni...
- AliveCor, Inc., Allengers Medical Systems Ltd., Bionet America, Inc., Biotricity, Inc., Cardioline S.P.A., GE Healthcare, and Medtronic Plc are som...
Comprehensive tutorial on ECG interpretation, covering normal waves, durations, intervals, rhythm and abnormal findings. From basic to advanced ECG reading. Includes a complete e-book, video lectures, clinical management, guidelines and much more.
WAVE OR INTERVAL DURATION (msec) P wave duration – <120 msec; PR interval – <200 msec; QRS duration – <110-120 msec; QT interval (corrected) -≤440-450 msec
ECG’s provider valuation services include the following: Analyzing total compensation arrangements for hospital-employed physicians and advanced practice providers (APPs) Developing and assessing call coverage, medical directorship, and recruitment arrangements.
