Overview
- Pericarditis represents acute or chronic inflammation of the pericardium
- Characteristic exam findings: (1) retrosternal, pleuritic chest pain that is worse when lying flat and relieved by leaning forward; (2) dyspnea; and, (3) tachycardia
- May be associated with a pericardial friction rub or pericardial effusion
- Diffuse ST-segment changes are the result of epicardial involvement (ie, myopericarditis)
ECG Features
- Diffuse concave ST-segment elevation and PR depression throughout most of limb leads (I, II, III, aVL, aVF) and precordial leads (V2-6)
- Reciprocal ST-segment depression and PR elevation in lead aVR (± V1)
- Sinus tachycardia is common in acute pericarditis from pain and/or pericardial effusion
- Note: the above ST- and PR-segment deviations should be measured relative to the baseline formed by the TP segment
ECG Stages
- Stage 1 (1-2 weeks): widespread ST elevation and PR depression with reciprocal changes in aVR
- Stage 2 (1-3 weeks): normalization of ST changes + generalized T wave flattening
- Stage 3 (3+ weeks): flattened T waves become inverted
- Stage 4 (4+ weeks): normalization of ECG
Causes
- Infectious: viral (most common; eg, coxsackie virus), bacterial, fungal, tuberculosis
- Immunologic: rheumatic fever, lupus
- Others: uremia, post-myocardial infarction/Dressler’s syndrome, post-precardiotomy syndrome, paraneoplastic syndromes, trauma, post-radiotherapy
- Drugs: isoniazid, cyclopsporine
Pericarditis versus Benign Early Repolarization (BER)
- Both conditions are associated with concave ST elevation making it difficult to distinguish the two
- Two ways to help differentiate: (1) ST segment/T wave ratio, (2) fish-hook pattern
- (1) ST segment/T wave ratio: measure the vertical height of ST segment elevation (ie, from end of PR segment to J point) and compare it to the T wave amplitude in V6 (ratio >0.25 suggested pericarditis; ratio <0.25 suggests BER)
- (2) Fish-hook pattern: presence of a notched or irregular J point (“fish hook”) suggests BER (best seen in lead V4)
ECG Features Favoring Pericarditis
- ST elevation: diffuse/widespread
- PR depression: present
- T wave amplitude: normal
- ST segment/T wave ratio: >0.25
- Fish-hook pattern (V4): absent
- ECG changes: evolve slowly over time
ECG Features Favoring Benign Early Repolarization (BER)
- ST elevation: limited to precordial leads
- PR depression: absent
- T wave amplitude: increased (prominent)
- ST segment/T wave ratio: <0.25
- Fish-hook pattern (V4): present
- ECG changes: stable over time
Pericarditis versus STEMI
- Pericarditis can have localized ST elevation, but there should be no reciprocal depression (except in leads aVR and V1)
- PR depression only reliably seen in viral pericarditis and often only an early transient phenomenon lasting hours; PR depression (or PR elevation in lead aVR) can also be seen in an atrial infarction
- STEMI can have concave-up ST elevation like pericarditis
- Only STEMI causes convex-up or horizontal ST elevation
- Like pericarditis, STEMI can cause positional/pleuritic chest pain and a pericardial friction rub
- ST elevation greater in lead III than lead II suggests STEMI
Approach to differentiate pericarditis from STEMI
- 1. Is ST depression present in a lead other than aVR or V1? If yes => STEMI
- 2. Is there convex-up or horizontal ST elevation? If yes => STEMI
- 3. Is there ST elevation greater in lead III than lead II? If yes => STEMI
- 4. Is PR depression present in multiple leads? If yes => pericarditis (especially in the presence of a pericardial friction rub)
Example ECG
Patient: 62-year-old with an upper respiratory symptoms for the last 2 weeks presents with pleuritic chest pain that prevents her from sleeping and is relieved by sitting upright; physical exam reveals a regular, tachycardic pulse rate and a pericardial friction rub
ECG interpretation: sinus tachycardia, incomplete right bundle branch block, acute pericarditis
– Ventricular rate 112 BPM
– PR interval 132 ms
– QRS duration 102 ms
– QT/QTc 348/475 ms
– P-R-T axes 57 46 28
Key Points from Example ECG
- Sinus tachycardia – common in pericarditis
- Widespread concave ST elevation and PR depression throughout precordial (V2-V6) and limb (I, II, III, aVL, aVF) leads
- Reciprocal ST depression and PR elevation in lead aVR +/- V1
- ST elevation in lead II greater than lead III
- ST segment/T wave ratio: >0.25
- No fish hook pattern in lead V4
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