Clinical Notes : Cardiology

114. ECG - Pericarditis

ECG - Pericarditis

Definitions

  • Inflammation of the pericardium (e.g. following viral infection)

    • produces

      • characteristic chest pain (retrosternal, pleuritic, worse on lying flat, relieved by sitting forward),

      • tachycardia and

      • dyspnoea.

    • ​Widespread ST segment changes occur due to involvement of the underlying epicardium (i.e. myopericarditis)

    • There may be an associated pericardial friction rub or evidence of a pericardial effusion.

Features

  • Widespread concave ST elevation and PR depression throughout most of the limb leads (I, II, III, aVL, aVF) and precordial leads (V2-6).

  • Reciprocal ST depression and PR elevation in lead aVR (± V1).

  • Sinus tachycardia is also common in acute pericarditis due to pain and/or pericardial effusion.

 

Stages of pericarditis

Pericarditis is classically associated with ECG changes that evolve through four stages.

  • Stage 1 – widespread STE and PR depression with reciprocal changes in aVR (occurs during the first two weeks)

  • Stage 2 – normalization of ST changes; generalized T wave flattening (1 to 3 weeks)

  • Stage 3 – flattened T waves become inverted (3 to several weeks)

  • Stage 4 – ECG returns to normal (several weeks onwards)

NB. Less than 50% of patients progress through all four classical stages and evolution of changes may not follow this typical pattern.

 
 
 

ST elevation and PR depression

Widespread concave ST elevation and PR depression throughout most of the limb leads (I, II, III, aVL, aVF) and precordial leads (V2-6)

NB. ST- and PR-segment changes are relative to the baseline formed by the T-P segment. 

The degree of ST elevation is typically modest (0.5 – 1mm).

 

PR depression and ST elevation in V5

 

Reciprocal ST depression and PR elevation

 

Reciprocal ST depression and PR elevation in lead aVR (± V1).

Reciprocal PR elevation and ST depression in aVR

 

12 lead ECG : example 1

  • Widespread concave ST elevation and PR depression is present throughout the precordial (V2-6) and limb leads (I, II, aVL, aVF).

  • There is reciprocal ST depression and PR elevation in aVR.

Pericarditis

 

12 lead ECG : example 2

 

  • Sinus tachycardia

  • Widespread concave STE and PR depression (I, II, III, aVF, V4-6).

  • Reciprocal ST depression and PR elevation in V1 and aVR

Pericarditis

 

Pericarditis vs Benign Early Repolarisation

 

Pericarditis can be difficult to differentiate from Benign Early Repolarisation (BER) as both conditions are associated with concave ST elevation.

One useful trick to distinguish between these two entities is to look at the ST segment / T wave ratio and the Fish Hook Pattern

Features suggesting BER

  • ST elevation limited to the precordial leads

  • Absence of PR depression

  • Prominent T waves

  • ST segment / T wave ratio < 0.25

  • Characteristic “fish-hook” appearance in V4

  • ECG changes usually stable over time (i.e non-progressive)

 

Features suggesting pericarditis

  • Generalised ST elevation

  • Presence of PR depression

  • Normal T wave amplitude

  • ST segment / T wave ratio > 0.25

  • Absence of “fish hook” appearance in V4

  • ECG changes evolve slowly over time

NB. These features have limited specificity, therefore it may not always be possible to tell the difference between these two conditions

ST segment / T wave ratio:

  • The vertical height of the ST segment elevation (from the end of the PR segment to the J point) is measured and compared to the amplitude of the T wave in V6.

  • A ratio of > 0.25 suggests pericarditis

  • A ratio of < 0.25 suggests BER

Benign Early Repolarisation

  • ST segment height = 1 mm

  • T wave height = 6 mm

  • ST / T wave ratio = 0.16

  • The ST / T wave ratio < 0.25 is consistent with BER

Pericarditis

  • ST segment height = 2 mm

  • T wave height = 4 mm

  • ST / T wave ratio = 0.5

  • The ST / T wave ratio > 0.25 is consistent with pericarditis.

Fish Hook Pattern :

  • Another clue that suggests BER is the presence of a notched or irregular J point: the so-called “fish hook” pattern.

  • This is often best seen in lead V4.

Fish Hook pattern in BER

  • Notched J-point elevation in V4 with a “fish hook” morphology, characteristic of BER

 

Pericarditis vs STEMI :

Steps to distinguish pericarditis from STEMI:

  1. Is there ST depression in a lead other than AVR or V1? This is a STEMI

  2. Is there convex up or horizontal ST elevation? This is a STEMI

  3. Is there ST elevation greater in III than II? This is a STEMI

  4. Now look for PR depression in multiple leads… this suggests pericarditis (especially if there is a friction rub!)

 
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