Most Accurate Way to Read a Ekg Strip

---

This guide demonstrates how to read an ECG using a systematic arroyo. If y'all desire to put your ECG estimation knowledge to the examination, check out our ECG quiz on the Geeky Medics quiz platform.

You may also be interested in our ECG flashcard deck which can exist purchased as part of our drove of 1000+ OSCE flashcards.

---

Ostend details

Before starting time ECG interpretation, you should check the following details:

• Ostend the proper noun and appointment of birth of the patient matches the details on the ECG.
• Check the date and time that the ECG was performed.
• Check the calibration of the ECG (usually 25mm/south and 10mm/1mV).

You might also be interested in our OSCE Flashcard Collection which contains over 2000 flashcards that encompass clinical examination, procedures, communication skills and information interpretation.

---

Heart rate

What's a normal adult heart rate?

• Normal: lx-100 bpm
• Tachycardia: > 100 bpm
• Bradycardia: < lx bpm

Regular middle rhythm

If a patient has a regular center rhythm their middle rate tin can be calculated using the following method:

• Count the number of big squares present within ane R-R interval.
• Divide 300 by this number to calculate heart charge per unit.

Middle rate adding case

• 4 big squares in an R-R interval
• 300/4 = 75 beats per minute

How to calculate a centre charge per unit on a normal ECG

Irregular heart rhythm

If a patient's eye rhythm is irregular the start method of heart rate calculation doesn't work (every bit the R-R interval differs significantly throughout the ECG). As a issue, you need to use a different method:

• Count the number of complexes on the rhythm strip (each rhythm strip is typically 10 seconds long).
• Multiply the number of complexes past vi (giving y'all the average number of complexes in one infinitesimal).

Heart rate calculation example

• x complexes on a rhythm strip
• 10 x 6 = 60 beats per minute

---

Heart rhythm

A patient'southward heart rhythm tin be regular or irregular.

Irregular rhythms tin can be either:

• Regularly irregular (i.e. a recurrent blueprint of irregularity)
• Irregularly irregular (i.eastward. completely disorganised)

Mark out several consecutive R-R intervals on a slice of paper, and so movement them along the rhythm strip to check if the subsequent intervals are similar.

Hint

If y'all are suspicious that in that location is some atrioventricular block (AV cake), map out the atrial rate and the ventricular rhythm separately (i.eastward. mark the P waves and R waves). Equally you move along the rhythm strip, y'all can then run into if the PR interval changes, if QRS complexes are missing or if in that location is complete dissociation between the 2.

Measure the R-R intervals to assess if the rhythm is regular or irregular¹

---

Cardiac axis

Cardiac centrality describes the overall direction of electric spread within the eye.

In a healthy private, the centrality should spread from xi o'clock to five o'clock.

To determine the cardiac centrality you need to look at leads I, Ii and 3.

Read our cardiac axis guide to learn more than.

Normal cardiac axis

Typical ECG findings for normal cardiac axis:

• Lead II has the most positive deflection compared to leads I and 3.

Normal cardiac centrality

Right axis deviation

Typical ECG findings for correct axis difference:

• Pb III has the near positive deflection and pb I should be negative.
• Correct axis deviation is associated with right ventricular hypertrophy.

Right centrality deviation ⁱⁱ

Left centrality difference

Typical ECG findings for left axis divergence:

• Lead I has the most positive deflection.
• Leads Two and III are negative.
• Left axis deviation is associated with middle conduction abnormalities.

Left centrality departure ²

---

P waves

The next step is to look at the P waves and answer the following questions:

one. Are P waves nowadays?

two. If so, is each P wave followed past a QRS circuitous?

3. Do the P waves look normal? – check duration, direction and shape

4. If  P waves are absent-minded, is there any atrial activeness?

• Sawtooth baseline → flutter waves
• Chaotic baseline → fibrillation waves
• Flat line → no atrial activity at all

Hint

If P waves are absent and at that place is an irregular rhythm it may suggest a diagnosis of atrial fibrillation.

P waves ¹

---

PR interval

The PR interval should be between 120-200 ms(3-v small squares).

Prolonged PR interval (>0.2 seconds)

A prolonged PR interval suggests the presence of atrioventricular delay (AV cake).

Outset-degree heart block (AV cake)

First-degree center block involves a fixed prolonged PR interval (>200 ms).

First-degree center block (AV block)

2d-degree centre block (blazon 1)

Second-caste AV block (blazon 1) is also known asMobitz type 1 AV block orWenckebach phenomenon.

Typical ECG findings in Mobitz type i AV block includeprogressive prolongation of the PR interval until eventually the atrial impulse is not conducted and theQRS complex is dropped.

AV nodal conductionresumes with the side by side trounce and the sequence of progressive PR interval prolongation and the eventual dropping of a QRS complexrepeats itself.

Second-degree AV block (Mobitz Blazon ane – Wenckebach)

Second-degree heart block (blazon 2)

Second-degree AV block (type 2) is also known every bitMobitz blazon 2 AV block.

Typical ECG findings in Mobitz type 2 AV block include a consistent PR interval duration withintermittently dropped QRS complexes due to a failure of conduction.

The intermittent dropping of the QRS complexes typically follows arepeating cycle of every3rd (3:1 block) or4th (4:1 block)P wave.

2d-degree AV block (Mobitz type 2 AV block) ³

3rd-degree heart block (complete heart block)

3rd-caste (complete) AV block occurs when there is no electrical communicationbetween theatria andventricles due to a complete failure of conduction.

Typical ECG findings include thepresence of P waves andQRS complexes that haveno association with each other, due to the atria and ventricles functioning independently.

Cardiac role is maintained past ajunctional orventricularpacemaker.

Narrow-circuitous escape rhythms (QRS complexes of <0.12 seconds duration) originateabove the bifurcation of theparcel of His.

Broad-complex escape rhythms (QRS complexes >0.12 seconds duration) originate frombelow the bifurcation of the bundle of His.

Complete middle block (3rd degree) ^iv

Tips for remembering types of heart cake

To assistance remember the various types of AV block, it is useful to know the anatomical location of the cake within the conducting system.

Showtime-caste AV block:

• Occurs between the SA node and the AV node (i.due east. within the atrium).

2nd-degree AV block:

• Mobitz I AV cake (Wenckebach) occurs IN the AV node (this is the simply piece of conductive tissue in the heart which exhibits the power to conduct at different speeds).
• Mobitz Two AV block occurs AFTER the AV node in the bundle of His or Purkinje fibres.

Third-degree AV block:

• Occurs at or subsequently the AV node resulting in a complete occludent of distal conduction.

Shortened PR interval

If the PR interval is shortened, this can mean one of two things:

• But, the P wave is originating from somewhere closer to the AV node then the conduction takes less time (the SA node is not in a fixed place and some people's atria are smaller than others).
• The atrial impulse is getting to the ventricle by a faster shortcut instead of conducting slowly across the atrial wall. This is an accompaniment pathway and can be associated with a delta moving ridge (see below which demonstrates an ECG of a patient with Wolff Parkinson White syndrome).

Delta wave ⁵

---

QRS circuitous

When assessing a QRS circuitous, you lot need to pay attending to the following characteristics:

• Width
• Meridian
• Morphology

Diverse components of an ECG

Width

Width can be described as NARROW (< 0.12 seconds) or BROAD (> 0.12 seconds):

• A narrow QRS circuitous occurs when the impulse is conducted downwards the parcel of His and the Purkinje fibre to the ventricles. This results in well organised synchronised ventricular depolarisation.
• A broad QRS complex occurs if there is an aberrant depolarisation sequence – for example, a ventricular ectopic where the impulse spreads slowly across the myocardium from the focus in the ventricle. In contrast, an atrial ectopic would effect in a narrow QRS complex considering it would conduct downwardly the normal conduction system of the eye. Similarly, a bundle branch cake results in a broad QRS complex because the impulse gets to 1 ventricle chop-chop downwardly the intrinsic conduction organization then has to spread slowly across the myocardium to the other ventricle.

Height

Elevation tin be described as either Small-scale or TALL:

• Modest complexes are defined as < 5mm in the limb leads or < x mm in the chest leads.
• Alpine complexes imply ventricular hypertrophy (although can be due to body habitus e.g. tall slim people). There are numerous algorithms for measuring LVH, such every bit the Sokolow-Lyon index or the Cornell index.

Morphology

To assess morphology, you need to assess the individual waves of the QRS complex.

Delta moving ridge

The mythical 'delta wave' is a sign that the ventricles are being activated earlier than normal from a betoken distant to the AV node. The early activation and then spreads slowly across the myocardium causing the slurred upstroke of the QRS circuitous.

Note – the presence of a delta moving ridge does NOT diagnose Wolff-Parkinson-White syndrome. This requires evidence of tachyarrhythmias AND a delta wave.

Delta moving ridge ^five

Q-waves

Isolated Q waves can exist normal.

A pathological Q moving ridge is > 25% the size of the R wave that follows it or > 2mm in height and > 40ms in width.

A single Q wave is non a cause for concern – look for Q waves in an entire territory (e.yard. anterior/inferior) for evidence of previous myocardial infarction.

Q waves (V2-V4), with T wave inversion suggestive of previous anterior MI⁶

R and Southward waves

Assess the R wave progression across the chest leads (from small in V1 to large in V6).

The transition from South > R wave to R > Southward moving ridge should occur in V3 or V4.

Poor progression (i.e. S > R through to leads V5 and V6) can exist a sign of previous MI but can as well occur in very large people due to poor lead position.

Poor R wave progression ⁷

J indicate segment

The J point is where the S wave joins the ST segment.

This betoken tin be elevated resulting in the ST segment that follows it also existence raised (this is known every bit "high have-off").

High have-off (or benign early on repolarisation to requite its full championship) is a normal variant that causes a lot of angst and confusion every bit it LOOKS similar ST summit.

Key points for assessing the J bespeak segment:

• Benign early repolarisation occurs mostly under the age of l (over the historic period of l, ischaemia is more common and should exist suspected first).
• Typically, the J point is raised with widespread ST tiptop in multiple territories making ischaemia less likely.
• The T waves are as well raised (in dissimilarity to a STEMI where the T wave remains the same size and the ST segment is raised).
• The ECG abnormalities do non change! During a STEMI, the changes will evolve – in benign early repolarisation, they will remain the aforementioned.

---

ST segment

The ST segment is the part of the ECG between the end of the S moving ridge and the start of the T wave.

In a good for you private, it should be an isoelectric line (neither elevated nor depressed).

Abnormalities of the ST segment should be investigated to dominion out pathology.

Various components of an ECG

ST-elevation

ST-superlative is meaning when it is greater than 1 mm (1 small square)in 2 or more contiguous limb leads or >2mm in ii or more chest leads.

Information technology is virtually normally acquired by astute full-thickness myocardial infarction.

ST top in the anterior leads

ST depression

ST depression ≥ 0.5 mm in ≥ 2 face-to-face leads indicates myocardial ischaemia.

ST depression

---

T waves

T waves represent repolarisation of the ventricles.

Tall T waves

T waves are considered tall if they are:

• > 5mm in the limb leads AND
• > 10mm in the chest leads (the same criteria equally 'minor' QRS complexes)

Alpine T waves tin be associated with:

• Hyperkalaemia ("tall tented T waves")
• Hyperacute STEMI

Alpine tented T waves ^viii

Inverted T waves

T waves are ordinarily inverted in V1 and inversion in lead III is a normal variant.

Inverted T waves in other leads are a nonspecific sign of a broad variety of conditions:

• Ischaemia
• Bundle co-operative blocks (V4-6 in LBBB and V1-V3 in RBBB)
• Pulmonary embolism
• Left ventricular hypertrophy (in the lateral leads)
• Hypertrophic cardiomyopathy (widespread)
• General disease

Around 50% of patients admitted to ITU have some prove of T moving ridge inversion during their stay.

Find the distribution of the T moving ridge inversion (e.g. inductive/lateral/posterior leads).

You must take this ECG finding and utilize information technology in the context of your patient.

Inverted T wave

Biphasic T waves

Biphasic T waves have two peaks and can be indicative of ischaemia and hypokalaemia.

Biphasic T wave ⁹

Flattened T waves

Flattened T waves are a non-specific sign, that may represent ischaemia or electrolyte imbalance.

Flattened T moving ridge ⁹

---

U waves

U waves are non a common finding.

The U moving ridge 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).

U wave ¹⁰

---

Document your interpretation

You should document your interpretation of the ECG in the patient'due south notes (check out our guide to documenting an ECG).

---

References

1. James Heilman, Dr.. Fast atrial fibrillation. Licence: CC Past-SA iii.0.
2. Michael Rosengarten BEng, MD.McGill. Right axis deviation. Licence: CC BY-SA 3.0.
3. James Heilman, MD. Mobitz type 2 AV block. Licence: CC BY-SA iii.0.
4. James Heilman, Doctor. Complete center block. Licence: CC BY-SA 3.0.
5. James Heilman, Dr.. Delta wave. Licence: CC Past-SA 3.0.
6. Michael Rosengarten BEng, MD.McGill. Q-waves. Licence: CC By-SA 3.0.
7. Michael Rosengarten BEng, Doc.McGill. Poor R-wave progression. Licence: CC BY-SA three.0.
8. Michael Rosengarten BEng, MD.McGill. Alpine tented T-waves. Licence: CC BY-SA 3.0.
9. CardioNetworks. T-wave morphology. Licence: CC Past-SA 3.0.
10. James Heilman, MD. U-wave. Licence: CC BY-SA 3.0.
11. Michael Rosengarten BEng, MD.McGill. Left axis deviation. Licence: CC Past-SA 3.0.

---

cherryplicaut.blogspot.com

Source: https://geekymedics.com/how-to-read-an-ecg/

Share this post