Transoesophageal and transthoracic recordings of mitral annulus motion

Abstract

Maximal systolic and diastolic velocities recorded from four sites of the mitral annulus motion (MAM) reflect left ventricular (LV) performance. This thesis focus on factors influencing M-mode derived velocities in healthy children and adults and reference values are proposed. The usefulness of M-mode and pulsed tissue Doppler in detecting diastolic disturbances in patients with symptoms of heart failure are investigated as well. Also the reproducibility of transoesofageal (TE) recordings of long-axis movements and the difference to transthoracic (TT) recordings in anaesthetized patients are described as is the influence of respiration.

By applying tangents to M-mode echocardiography recordings from apical 2- and 4-chamber views the maximal systolic long axis velocity (MLACV) and maximal diastolic relaxation velocities (RVm) were measured. Based on stepwise multiple regression analysis concerning age, weight, height, body surface area and heart rate the following equations are suggested for calculation of reference values:

In children and adolescents under 18: MLACV (mm⁻¹) = 2.5 x Age (years) + 49.0, (±20.2) (±2 SEE); RVm (mm⁻¹) = 171 - 0.54 x Heart rate, (±37.4) (±2 SEE).

In adults: MLACV (mm⁻¹) = 0.75 x Height (cm) -50.5, (±19.6) (±2 SEE); RVm (mm⁻¹) = 163 - 1.29 x Age, (±16.8) (±2 SEE).

Intra- and inter-individual reproducibility expressed as the coefficient of variation for MLACV was 4.7% and 4.9% respectively.

In 64 patients with symptoms of heart failure the LV inflow and lung vein flow profiles were obtained by pulsed Doppler recordings and patients were classified as true cases of abnormal diastolic function by age corrected reference values. M-mode (M-RVm) and pulsed Doppler tissue imaging (TD-RVm) were used for recordings of RVm and according to Fisher's exact test both methods can be used to detect diastolic dysfunction but velocities obtained by TD-RVm was 29.7% (p<0.0001) higher than M-RVm. Sensitivity and specificity for M-RVm to correctly detect diastolic dysfunction were 89% and 81% respectively and for TD-RVm 81% and 78%. TD-RVm and M-RVm were highly correlated (r = 0.87).

Differences in TT and TE recordings of MAM were investigated in 24 healthy anaesthetized patients by using tissue velocity imaging. Another 10 patients were enrolled for the reproducibility study. The anterior site has low reproducibility and should be omitted when comparing TE and TT values. A TE mean value from three sites is about 15% lower than a TT mean value from four sites. Only systolic and early diastolic velocities have acceptable reproducibility values. Respiration does not influence MLACV or RVm during anaesthesia but RVm is about 5% higher during expiration in awake individuals.