How do you recognize myocardial infarction or heart valve disease using strain imaging echocardiography? You have to take a good look at the strain graph and the bull’s-eye plot. There’s even a way to assess hypertrophy of the left ventricle with this ultrasound modality.
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The evaluation of myocardial function can be tricky. This course will help you master an easy-to-follow process on how to acquire, optimize, and interpret left ventricular strain images. Using hands-on tips and tricks, you’ll cover global longitudinal strain (GLS) as well as important pearls and pitfalls as we go through several exciting real-life examples. Get ready to become an echo expert!
Left ventricular dysfunction with subsequent heart failure is the final common pathway for several cardiovascular diseases. In this MedMastery lesson, we will review the clinical applications of strain imaging in detecting cardiac disorders, primarily focusing on indications and pathologies that you should be aware of when performing strain imaging. Let's begin with how strain imaging can be used to detect myocardial infarction.
In a normally functioning heart the strain graph that represents all of the wall segments should be in sync with end slope down at the time of aortic valve closure or AVC. On the bulls-eye plot, the strain segments should be all red, indicating that the myocardium is contracting normally, and the GLS value will be less than or equal to minus 18%, which represents normal overall left ventricle function.
In the case of myocardial infarction, or left ventricle dysfunction, the strain graphs are not in sync with or sloped downward together with the AVC, and the wall segments don't move in the same way indicated by the disorganized lines. On the bulls-eye plot, any akinetic or aneurysmal basal walls indicated by blue, suggests myocardial dysfunction, and regional specific patterns of ischemia or infarction. This can be determined by looking at the GLS value, which will be less negative. In addition, strain imaging can detect a mild reduction in systolic shortening in the absence of regional wall motion abnormalities, or left ventricular ejection fraction reduction, indicated by the pink areas on the bulls-eye map.
So, in left ventricle dysfunction cases, strain imaging can produce different qualitative and quantitative data for you to analyze and confirm any abnormalities. Moving on to heart valve disease. Heart valve disease such as valvular stenosis occurs when the heart valve does not open or close properly. Research has shown that strain imaging can detect myocardial damage earlier in patients with an asymptomatic aortic stenosis, and a normal left ventricular ejection fraction.
The GLS values were found to be greater than minus 18%, for example, minus 17, or minus 16, in comparison to those from normal healthy heart with GLS value less than minus 18%, for example, minus 19, or even minus 20%. The strain graph and GLS values will look very similar to the ones we described for myocardial infarction. So even though the left ventricular contraction looks normal, strain imaging can detect myocardial damage earlier. Lastly, strain imaging can be used to assess hypertrophy.
In the case of increased wall thickness, and the left ventricle mass, GLS analysis can detect subtle changes in the myocardium and monitor the progression of these changes in the presence of a normal left ventricular ejection fraction. For example, this patient has a basal septal bulge due to hypertrophy, which indicate early signs of ventricular remodeling and will affect the strain imaging data. Specifically, it can reduce strain near the basal and middle left ventricle wall segments, the values will be less negative and closer to zero, which will also decrease the average GLS value.
In the case of increased left ventricle wall thickness and/or mass from hypertrophy, or cardiomyopathy, systolic function is usually normal because the left ventricle cavity volumes are reduced. But analyzing the pattern of strain can help identify regional segments that may be reduced due to hypertrophy. Hypertrophied regions have reduced myocardial defamation and therefore produce strain values closer to zero. So the bulls-eye plot will display shades of pale pink, suggesting a reduction in their formation and the overall average GLS will be reduced. If performed correctly, strain imaging can help you detect early changes in the left ventricle and diagnosing cardiac pathologies accurately helps cardiologist make better clinical decisions for optimal patient care.