myocardial viability
The presence of living, potentially functional myocardial tissue in regions with reduced contractile function.
Full Definition
Myocardial viability refers to the identification of hibernating or stunned myocardium that retains metabolic activity and potential for functional recovery despite current contractile dysfunction. Viable myocardium can be detected through various imaging modalities including dobutamine stress echocardiography, nuclear perfusion imaging with thallium or technetium, positron emission tomography, or delayed-enhancement cardiac MRI. Assessment of viability is crucial in determining whether revascularization will improve left ventricular function and clinical outcomes in patients with ischemic cardiomyopathy. The presence of significant viable myocardium (typically >50% of wall thickness) in dysfunctional segments predicts functional improvement following successful revascularization.
Usage
Usage note: Distinguish from myocardial perfusion; viability refers to tissue metabolic activity, not blood flow.
In Context
- "PET imaging demonstrated myocardial viability in the anterior wall despite severe hypokinesis." — Nuclear cardiology report
- "The decision to proceed with revascularization was based on evidence of significant myocardial viability on delayed-enhancement MRI." — Heart team discussion note