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Transmural heterogeneity of myocardial contraction and ischemia. Diagnosis and clinical implications
P Colonna1, C Cadeddu, R Montisci
1Department of Cardiovascular and Neurological Sciences, University of Cagliari, Italy. pcolcard@pacs.unica.it
Insights
New ultrasound techniques can now differentiate subendocardial from transmural myocardial infarction. This improves diagnosis and treatment of cardiac patients by assessing transmural extension of myocardial necrosis.
Area of Science:
- Cardiology
- Medical Imaging
Background:
- Myocardial contraction is heterogeneous, with greater force in subendocardial than subepicardial layers.
- The subendocardium is the most vulnerable myocardial layer during acute ischemia or infarction.
Purpose of the Study:
- To evaluate novel ultrasonographic techniques for distinguishing subendocardial from transmural myocardial ischemia or infarction.
- To highlight the importance of assessing transmural extension in acute myocardial infarction diagnosis and treatment.
Main Methods:
- Utilized novel ultrasonographic techniques, including tissue characterization with integrated backscatter and Doppler tissue imaging.
- Employed nuclear magnetic resonance tagging for investigating myocardial contraction in different transmural layers.
Main Results:
- Conventional echocardiography cannot determine the transmural extent of ischemia or infarction.
- Novel techniques can differentiate subendocardial from transmural ischemia/infarction, providing crucial diagnostic information.
- Assessing transmural wavefront development is critical for accurate diagnosis in acute myocardial infarction.
Conclusions:
- New ultrasonographic methods offer improved diagnostic capabilities for myocardial ischemia and infarction.
- These advancements provide better opportunities for appropriate diagnosis and future treatment strategies in cardiac patients.
- Understanding transmural extension is vital for managing left ventricular dysfunction and size post-infarction.
Abstract:
Myocardial contraction behaves heterogeneously, being greater in subendocardial than in subepicardial layers. Similarly, during acute myocardial ischemia or infarction, the subendocardium is the first myocardial layer to suffer. Conventional two-dimensional echocardiography cannot distinguish the transmural extension of myocardial ischemia or infarction, showing akinesia also when only the subendocardium is affected. Novel ultrasonographic techniques (like tissue characterization with integrated backscatter or Doppler tissue imaging) and nuclear magnetic resonance tagging can investigate myocardial contraction in different transmural layers and distinguish subendocardial from transmural ischemia or infarction. With the advent of thrombolysis and primary angioplasty in the acute phase of myocardial infarction a correct diagnosis of the extension of myocardial necrosis cannot ignore its transmural wavefront development. The salvage of the subepicardial layer does not give direct information on overall myocardial thickening but is one of the major determinants of overall left ventricular dysfunction and size. Although it is still necessary to investigate this phenomenon, new ultrasonographic techniques give us important information and more opportunities to appropriate diagnosis and future treatment of cardiac patients.