Mitral Ring Motion in Assessment of Left Ventricular Function
Abstract: The motion of the mitral ring was studied with M-mode echocardiography using the apical four- and two-chamber views.With the purpose of obtaining adequate reference materials for mitral ring motion, 70 healthy subjects were studied. Stepwise multiple regression analysis with age, gender, height, weight, body i surface area and heart rate as independent variables, showed that ring motion amplitude (mm) is best i described as 2.2 + 0.078 x height (cm) (SD = 1.0 mm) in subjects under age 18, and as 12.7- 0.060 [ x age (years)+ 0.031 x height (cm) (SD = 1.2 mm) in subjects over age 18, or if only age is taken ! into account as 18.4-0.065 x age (SD = 1.2 mm).Both in children and adults the atrial contribution to the total mitral ring motion was best described as 0.15 + 0.0039 x age (SD = 0.027).Comparison between the four sites of measuring showed that the mitral ring "tilts" slightly during the systolic motion towards the apex. The septal point moved significantly less than the lateral point (pIn 20 healthy subjects changes in mitral ring motion and in short axis contractions with respiration was studied. It was shown that the decrease in left ventricular stroke volume on inspiration is a net effect of decrease in diastolic short axis diameter by 4.8% (p<0.001) and an increase in mitral ring motion by 5.5% (p<0.001).In 40 healthy subjects aged 18 - 70 years changes in long axis and short axis contraction with increasing age was studied. It was shown that from age 18 to age 70 the long axis systolic shortening[ decreases by 20% (p<0.001) and minor axis shortening increases by 18% (p=0.012). These findings have important implications for the calculation of ejection fraction (EF) from M-mode measurements.In 16 patients with left ventricular hypertrophy because of hypertension or hypertrophic cardiomyopathy, ejection fraction calculations were made by Teichholz' formula, by the equation EF 1'[ (%)=mitral ring motion (mm) x 5 and by Simpson .. s rule. Radionuclide angiography was used as , gold standard for ejection fraction. The study showed that in patients with hypertrophy Teichholz .. formula overestimates ejection fraction by 10% (6.7 EF%) (p--Q.002). Calculation by using mitral ring motion x 5 underestimates the ejection fraction by 19.3% ( 12.9 EF%) (p=0.002). Compared to healthy controls the hypertrophy group had 28.9% decreased mitral ring motion (pMaximal longitudinal diastolic relaxation velocity was investigated in 22 patients on day 3-21 after first transmural myocardial infarction. The maximal diastolic slope was measured on the M-mode recording from the mitral ring motion. Compared to healthy controls the patients had significantly decreased relaxation velocity (p
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