The mitral annular displacement by two-dimensional speckle tracking: a new tool in evaluating the left atrial function

Assessment of left atrial function using tissue motion annular displacement in healthy dogs

OBJECTIVES

Recently, tissue motion annular displacement by speckle tracking has been shown to be a reliable method for evaluating deformation of the left atrium in healthy dogs. The aim of this study was to investigate whether tissue motion annular displacement is a feasible alternative method for studying left atrial function.

MATERIALS AND METHODS

One hundred healthy dogs were included. Left atrial function was assessed by tissue motion annular displacement, which was correlated to the left atrial strain and biplane area-length method-derived volumes. Left atrial reservoir function was evaluated by left atrial global tissue motion annular displacement, global left atrial strain and left atrial emptying fraction, while left atrial systolic tissue motion annular displacement and left atrial ejection fraction were used to assess left atrial systolic function.

RESULTS

A statistically significant association between body weight and the dependent variables others than age was found. Indexed global and systolic tissue motion annular displacement decreased as body weight increased. Global iTMAD_AIIometric (mm/∛kg) showed a moderate, positive correlation with left atrial emptying fraction and with global left atrial strain. Systolic iTMAD_AIIometric (mm/∛kg) showed a moderate correlation with left atrial ejection fraction. Coefficients of variation for the intraobserver and interobserver analyses were 8.3% and 20.3% for global and 10.5% and 18.9% for systolic tissue motion annular displacement, respectively.

CLINICAL SIGNIFICANCE

Tissue motion annular displacement is a feasible and simple method for the evaluation of left atrial function. Our study documented the effects of body weight on left atrial tissue motion annular displacement, indicating that tissue motion annular displacement must be indexed to body weight. No influence of age or heart rate was observed on tissue motion annular displacement.

Timolol 0.5% ophthalmic solution influences cardiac function in healthy cats

OBJECTIVES

The aim of this study was to ascertain the effect of a drop of timolol 0.5% ophthalmic solution on the systolic function of the left ventricle (LV) and left atrium (LA), and to confirm if timolol helped appraisal of diastolic function by reducing heart rate (HR) and separating the transmitral outflow waves from tissue Doppler imaging (TDI).

METHODS

A total of 41 client-owned healthy cats underwent two echocardiograms 20 mins apart. The timolol group (33 cats) received a drop of timolol solution after the first examination. Standard and speckle-tracking echocardiography evaluated the LV and LA function of both groups at the two time points evaluated.

RESULTS

Timolol reduced HR (19%), and fractional shortening from LV (20.3%) and LA (16.6%). Septal S' decreased by 51% (from 7.7 to 5.2 cm/s) and lateral S' dropped by 43.1% (7.3 to 5.1 cm/s). Most longitudinal techniques did not change after timolol, including the mitral annular plane systolic excursion from the interventricular annulus, tricuspid annular plane systolic excursion, LV longitudinal strain and LV tissue motion annular displacement. The isovolumic relaxation time increased by 15.2% (from 54 to 64.6 ms), with most cats presenting this variable above the reference (>60 ms). Timolol did not support diastolic assessment, enabling evaluation in only 2/11 cats when using lateral TDI and 1/9 cats using septal TDI. Regarding side effects, miosis occurred in 18 cats (54.5%).

CONCLUSIONS AND RELEVANCE

Timolol reduced systolic function, decreasing standard echocardiographic variables. Regarding diastolic evaluation, although timolol decreased HR, it did not separate the mitral diastolic waves, as expected.