In aortic stenosis M-mode imaging, what happens to the left ventricular ejection-fraction slope?

In aortic stenosis M-mode imaging, what happens to the left ventricular ejection-fraction slope?

• A. Slope increases due to greater LV compliance
• B. Slope reduces due to change in LV compliance
• C. Slope remains unchanged
• D. Slope becomes negative

Answer: (B)

In aortic stenosis, the left ventricle adapts with concentric hypertrophy, which makes the ventricle stiffer and less compliant. This change affects how quickly the ventricle can shorten during systole, a measurement you glimpse on M-mode known as the ejection-fraction slope—the rate at which the LV dimension decreases as it ejects blood. With reduced compliance and higher afterload, the ventricle cannot shorten as rapidly, so the systolic dimension change is slower. That produces a reduced ejection-fraction slope on M-mode. Even if the overall ejection fraction might still appear normal early on, the slope itself drops because the heart is working against stiffer walls and greater resistance. An increasing slope would imply more compliant or faster shortening, which isn’t the situation in stenosis; remaining unchanged doesn’t reflect the impact of the stiff, high-afterload ventricle; becoming negative would suggest abnormal lengthening during systole, which isn’t physiologically correct.

In aortic stenosis, the left ventricle adapts with concentric hypertrophy, which makes the ventricle stiffer and less compliant. This change affects how quickly the ventricle can shorten during systole, a measurement you glimpse on M-mode known as the ejection-fraction slope—the rate at which the LV dimension decreases as it ejects blood. With reduced compliance and higher afterload, the ventricle cannot shorten as rapidly, so the systolic dimension change is slower. That produces a reduced ejection-fraction slope on M-mode. Even if the overall ejection fraction might still appear normal early on, the slope itself drops because the heart is working against stiffer walls and greater resistance. An increasing slope would imply more compliant or faster shortening, which isn’t the situation in stenosis; remaining unchanged doesn’t reflect the impact of the stiff, high-afterload ventricle; becoming negative would suggest abnormal lengthening during systole, which isn’t physiologically correct.