Main ECG features of diffuse changes
Electrocardiography is a primary screening method when myocardial damage is suspected. Diffuse myocardial changes manifest primarily as ventricular repolarization abnormalities.
Key changes include:
- ST-segment displacement from the isoelectric line;
- T-wave changes: flattening or the appearance of a negative (inverted) T wave.
Depending on the cause of the diffuse lesion (e.g., in infectious processes), sinus tachycardia, signs of myocardial hypoxia, and non-specific ST-T complex changes may also be recorded on the ECG.
Features in specific lesions
In certain forms of myocardial inflammation, the ECG picture may have specific features. For instance, in toxic myocarditis, conduction and rhythm disturbances are often added to non-specific repolarization changes.
Toxic injury is characterized by:
- PR interval prolongation;
- Pronounced ST-T complex changes;
- Development of blocks of varying severity.
In diffuse myocarditis as part of acute rheumatic fever (rheumatic carditis), ST-segment and T-wave changes also dominate the ECG, while rhythm and conduction disturbances are less common. The development of such diffuse myocarditis, especially when accompanied by heart failure decompensation, is a prognostically unfavorable factor.
Differential diagnosis and age norms
When evaluating an electrocardiogram, it is essential to consider the patient's age-related characteristics, particularly in pediatric practice.
In children, a standard ECG may often reveal:
- Sinus arrhythmia.
- Isolated incomplete right bundle branch block.
These findings by themselves are variants of age-related norm. They should not be misconstrued as a sign of myocarditis or diffuse myocardial injury. The diagnosis of diffuse changes must always be based on a comprehensive analysis of clinical, laboratory (troponins, CK-MB, AST) and instrumental data (primarily echocardiography, where diffuse injury reveals ventricular dilatation and reduced contractility).
Class and exam questions
What ST-T complex changes are characteristic of diffuse myocardial injury?
The most typical findings are ST-segment displacement, as well as T-wave flattening or inversion (negative T wave).
Does incomplete right bundle branch block always indicate myocardial damage in children?
No, in children, isolated incomplete RBBB is often an age-related variant of normal and, in the absence of other signs, does not indicate myocarditis.
What ECG changes are typical for toxic myocarditis?
In addition to ST-T changes, toxic myocarditis is characterized by PR interval prolongation and the development of heart blocks of varying severity.
What else to study on this topic
- Echocardiographic signs of dilated cardiomyopathy in diffuse myocarditis
- The role of cardiospecific markers (troponins, CK-MB, AST) in the diagnosis of myonecrosis
- Application of contrast-enhanced cardiac MRI to detect active inflammation
- Morphological types and outcomes of rheumatic endocarditis
- Instrumental diagnostics of rheumatic carditis and the development of heart valve diseases
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