P1744 Motion and velocity of the different parts of the AV plane. Relation to site and wall length
Abstract Background Displacement (MAPSE) and peak systolic velocity (S") of the various parts of the mitral annulus differ. Also, both indices are higher in the right ventricular free wall. We aimed to investigate the relations between wall motion, wall lengths and sites in the left ventricle, as well as comparing to the right ventricle to assess the influence on systolic deformation of the AV-plane. Methods The HUNT study examined 1266 subjects without evidence of heart disease from a mixed urban/rural population of North Trøndelag county, S", linear diastolic left ventricular annulus to apex distance (WL) and MAPSE was measured in the septal, anterior, lateral and inferior points of the mitral annulus. Intra individual variance and relative variance (variance / mean) of S" and MAPSE was calculated and compared to the same variance of the values normalised for wall length (S"/WL and MAPSE/WL). Results Wall lengths, velocities and MAPSE are shown in figure 1. Wall lengths were associated with both MAPSE and S". Both wall lengths and motion were greatest in the free walls of the LV, but smallest in the septal parts of the AVplane. Variances are shown in table 1. Even if intra-individual variances are larger for S" than MAPSE, relative variance for both decreased by 80 - 90% when normalised for wall length. Conclusion There is an intra-individual variability of MAPSE and S" of the LV, corresponding to WL, when the values normalised for WL most of the variability disappears. Intra individual variability of strain and strain rate per wall is less than MAPSE and S" as shown earlier. As the apex is located centrally, walls corresponding to the free walls are longer than those closest to the septum, thus motion and wall length are both greatest corresponding to the LV free walls. Motion of the right ventricular free wall was higher than the LV free wall; TAPSE 2.8 cm, and S" 12.6 cm/s as shown previously. The relation of TAPSE and S" of the right ventricle to wall length will be different, as the afterload in the RV is far less. But as both lateral parts of the AV plane move more than the centre, givinga systolic bending of the AV-planealso as the central part of the AV-plane is centrally anchored to the large arteries as shown in fig. 1. Table 1 WL (cm) MAPSE (cm) MAPSE / WL (% points) S" (cm/s) S" / WL (/s) Mean of 4 walls 9.5 1.6 0.16 8.4 0.87 Variance 0.04 0.04 0.0004 1.2 0.01 Relative variance (%) 2.8 2.7 0.25 12.1 1.4 Wall lengths (WL), displacement(MAPSE), Systolic velocity (S") and mAPSE and S" normalised for WL. Means and intra individual variances. Abstract P1744 Figure. Fig. 1