- Email: [email protected]
Non-Invasive Assessment of In Vivo Myocardial Calcium Cycling by Mechanical Restitution Using Tissue Doppler Imaging
S34
Abstracts
Heart, Lung and Circulation 2007;16:S1–S201
ABSTRACTS
Conclusion: STE may prove to be a more sensitive and accurate method of assessing subclinical LV dysfunction prior to the decline in LVEF on 2DE or CGBPS. doi:10.1016/j.hlc.2007.06.087 83 Non-Invasive Assessment of In Vivo Myocardial Calcium Cycling by Mechanical Restitution Using Tissue Doppler Imaging M.M.H. Cheung 1,2,∗ , J.P. Mynard 1,2 , A.T. Hattam 1,2 , J.J. Smolich 1,2 , D.J. Penny 1,2 1 Department of Cardiology, Royal Children’s Hospital, Australia; 2 Australia & New Zealand Children’s Heart Research Centre, Murdoch Children’s Research Institute, Melbourne, Victoria, Australia
Background: Disturbances of myocardial calcium cycling occur in many clinical conditions and can be assessed from mechanical restitution profiles. While current in vivo evaluation of mechanical restitution is based on invasive measures (e.g. maximum rate of pressure rise, dP/dtmax ), a non-invasive approach would considerably expand the potential clinical utility of this technique. The aim of this study was to assess the feasibility of non-invasive assessment of mechanical restitution using tissue Doppler imaging (TDI). Methods: Studies were performed in six anaesthetised, open-chest adult sheep instrumented with an LV micromanometer catheter and left atrial pacing wires. Colour TDI data of the basal LV free wall were acquired by epicardial imaging from the cardiac apex (Vivid 7, GE Medical Systems), with parameters optimised to achieve frame rates > 200/s. With basal pacing rate set at 100, 120 or 133 beats/min, an extrastimulus (S2) was interposed with a cardiac stimulator at gradually shortening intervals after a train of nine normal beats (S1). Protocols were performed in triplicate. Peak s wave velocity (TDI) and dP/dtmax (micromanometer) of extrasystolic beats were measured independently by two observers. Results: Peak s velocity and LV dP/dtmax were highly correlated (r2 = 0.95, p < 0.0001). The relationships between the S1–S2 interval and peak s velocity or LV dP/dtmax paralleled one another and demonstrated a characteristic sigmoidal mechanical restitution response. Moreover, both relationships demonstrated a similar leftward shift with increased basal pacing rate. Conclusion: Non-invasive assessment of myocardial calcium cycling properties, as reflected in the mechanical restitution profile, can be accurately evaluated noninvasively with TDI (Figs. 1 and 2).
doi:10.1016/j.hlc.2007.06.088 84 Predictive Value of S Velocity using Doppler Tissue Imaging for Evaluation of Left Ventricular Ejection Fraction E.M. Chia 1,2,∗ , C. Hsieh 1,2 , T. Bui 1,2 , L. Thomas 1,2 1 Westmead
Hospital, Cnr Hawkesbury & Darcy Road, Westmead, NSW, Australia; 2 University of Sydney, Australia Aim: To determine if systolic contraction velocity (Svel) as measured by Doppler Tissue Imaging (DTI) on transoesophageal echocardiography (TOE) could be a surrogate measure of left ventricular ejection fraction (LVEF) in sinus rhythm (SR) and atrial fibrillation (AF). Background: TOE is commonly used intraoperatively for assessment of LVEF. Previous studies have shown that TOE DTI velocities are feasible and comparable to transthoracic velocities. Intraoperative Svel is more efficient and less dependent on acquisition of twodimensional images than LVEF calculation. Method: Thirty-four SR and 27 AF patients undergoing TOE were recruited. Patients with regional wall motion abnormalities or significant valvular disease were excluded. LVEF was estimated by Simpson’s method from the mid-oesophageal 4-chamber view. Svel was estimated as the maximal velocity of the mitral annular descent in systole from the septal annulus with the Doppler beam aligned with the septum. This was averaged over three beats. Results: In both groups, Svel increased with LVEF (SR: r = 0.69, p ≤ 0.001; AF: r = 0.53, p = 0.004). The AF group tended to be older (66.5 ± 13 years vs. 58.2 ± 14 years), and have a higher initial heart rate (87 ± 22 bpm vs.
Abstracts
Heart, Lung and Circulation 2007;16:S1–S201
ABSTRACTS
Conclusion: STE may prove to be a more sensitive and accurate method of assessing subclinical LV dysfunction prior to the decline in LVEF on 2DE or CGBPS. doi:10.1016/j.hlc.2007.06.087 83 Non-Invasive Assessment of In Vivo Myocardial Calcium Cycling by Mechanical Restitution Using Tissue Doppler Imaging M.M.H. Cheung 1,2,∗ , J.P. Mynard 1,2 , A.T. Hattam 1,2 , J.J. Smolich 1,2 , D.J. Penny 1,2 1 Department of Cardiology, Royal Children’s Hospital, Australia; 2 Australia & New Zealand Children’s Heart Research Centre, Murdoch Children’s Research Institute, Melbourne, Victoria, Australia
Background: Disturbances of myocardial calcium cycling occur in many clinical conditions and can be assessed from mechanical restitution profiles. While current in vivo evaluation of mechanical restitution is based on invasive measures (e.g. maximum rate of pressure rise, dP/dtmax ), a non-invasive approach would considerably expand the potential clinical utility of this technique. The aim of this study was to assess the feasibility of non-invasive assessment of mechanical restitution using tissue Doppler imaging (TDI). Methods: Studies were performed in six anaesthetised, open-chest adult sheep instrumented with an LV micromanometer catheter and left atrial pacing wires. Colour TDI data of the basal LV free wall were acquired by epicardial imaging from the cardiac apex (Vivid 7, GE Medical Systems), with parameters optimised to achieve frame rates > 200/s. With basal pacing rate set at 100, 120 or 133 beats/min, an extrastimulus (S2) was interposed with a cardiac stimulator at gradually shortening intervals after a train of nine normal beats (S1). Protocols were performed in triplicate. Peak s wave velocity (TDI) and dP/dtmax (micromanometer) of extrasystolic beats were measured independently by two observers. Results: Peak s velocity and LV dP/dtmax were highly correlated (r2 = 0.95, p < 0.0001). The relationships between the S1–S2 interval and peak s velocity or LV dP/dtmax paralleled one another and demonstrated a characteristic sigmoidal mechanical restitution response. Moreover, both relationships demonstrated a similar leftward shift with increased basal pacing rate. Conclusion: Non-invasive assessment of myocardial calcium cycling properties, as reflected in the mechanical restitution profile, can be accurately evaluated noninvasively with TDI (Figs. 1 and 2).
doi:10.1016/j.hlc.2007.06.088 84 Predictive Value of S Velocity using Doppler Tissue Imaging for Evaluation of Left Ventricular Ejection Fraction E.M. Chia 1,2,∗ , C. Hsieh 1,2 , T. Bui 1,2 , L. Thomas 1,2 1 Westmead
Hospital, Cnr Hawkesbury & Darcy Road, Westmead, NSW, Australia; 2 University of Sydney, Australia Aim: To determine if systolic contraction velocity (Svel) as measured by Doppler Tissue Imaging (DTI) on transoesophageal echocardiography (TOE) could be a surrogate measure of left ventricular ejection fraction (LVEF) in sinus rhythm (SR) and atrial fibrillation (AF). Background: TOE is commonly used intraoperatively for assessment of LVEF. Previous studies have shown that TOE DTI velocities are feasible and comparable to transthoracic velocities. Intraoperative Svel is more efficient and less dependent on acquisition of twodimensional images than LVEF calculation. Method: Thirty-four SR and 27 AF patients undergoing TOE were recruited. Patients with regional wall motion abnormalities or significant valvular disease were excluded. LVEF was estimated by Simpson’s method from the mid-oesophageal 4-chamber view. Svel was estimated as the maximal velocity of the mitral annular descent in systole from the septal annulus with the Doppler beam aligned with the septum. This was averaged over three beats. Results: In both groups, Svel increased with LVEF (SR: r = 0.69, p ≤ 0.001; AF: r = 0.53, p = 0.004). The AF group tended to be older (66.5 ± 13 years vs. 58.2 ± 14 years), and have a higher initial heart rate (87 ± 22 bpm vs.