Myocardial Work: Methodology and Clinical Applications

Figures

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  Figure 1. Pressure–strain loop (PSL) with valvular event timing and cardiac cycle phases. Global work index (GWI) represents the area of the loop from mitral valve closure (MVC) to mitral valve opening (MVO). Global constructive work (GCW) reflects the work that contributes to pump from aortic valve opening (AVO) to MVO. There is shortening during the ejection period and lengthening during isovolumic relaxation (IVRT). Global wasted work (GWW) represents the work that does not contribute to ejection. There is elongation of myocytes during the ejection period and shortening after the aortic valve closure (AVC) during IVRT.

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  Figure 2. Methodology of myocardial work (MW) for a patient with reduced ejection fraction (EF = 30%) due to cardiotoxicity. (A) Acquisition of apical four-, two-, and three-chamber view and evaluation of global longitudinal strain (GLS) with left ventricular (LV) bull’s eye; GLS = −10.8%. The highlighted button (with red circle) moves to the next step for myocardial work evaluation. (B) Introduction of systolic and diastolic blood pressure (red circle) and confirmation of the correct event timing in apical three-chamber view. The blue arrows point to mitral and aortic valves that should be clearly demonstrated. (C) Evaluation of global values of all MW components, including bull’s eye of the work index, global pressure–strain loop (red loop), and segmental pressure–strain loop (green loop), showing a dyssynchronous mid-septum segment and bars showing the relationship between the constructive (green bar) and wasted (blue bar) segmental (left) and global work. (D) Evaluation of the same global values as in image C but with different segment for pressure–strain loop analysis and with constructive/wasted work bars. Basal anterior segment with constructive work similar to the global one. Red…

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  Figure 3. Patient with ischemic cardiomyopathy. Red loop is equal to the global MWI of the patient, while green loops show the PSL of a normal and abnormal segment of LV. GLS = −7%, GWI = 532 mmHg%, GCW = 613 mmHg%, GWW = 146 mmHg%, GWE = 73%. Left green and blue bars of every screen represent the ratio of segmental constructive and wasted work, while bars at the right side represent their global values. You can appreciate the huge difference in the segmental values between the basal posterior segment (left screen) and the basal anterior segment (right screen) in a patient with extensive anterior myocardial infarction. The basal posterior creates a large pressure–strain loop and constructive work and contributes to ejection, while the basal anterior shows equal levels of constructive and wasted work.

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  Figure 4. Bull’s eye of GLS, GWI, and GWE showing global and segmental values in a normal heart. GLS = −20%, GWI = 1969 mmHg%, and GWE = 96%.

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  Figure 5. Bull’s eye of GLS, GWI, and GWE showing global and segmental values in a patient with ischemic cardiomyopathy. GLS= −7%, GWI = 532 mmHg%, GWE = 73%.