Right Ventricular Functional Abnormalities in ARVC | 49 SUPPLEMENTARY MATERIAL Supplement: deformation imaging methods RV deformation patterns Details on image acquisition and post-processing in echocardiographic deformation imaging were previously described extensively.1,2 Deformation graphs were derived by speckle tracking of the endocardial border of the RV lateral free wall in a focused apical 4-chamber view.1 After manual tracing, the wall was divided automatically into the basal, mid and apical segment. Multiple parameters were calculated and combined into a 3 type model. (Figure 1, panel A) The first parameter is the time to onset of shortening, also called the electro-mechanical interval (EMI). The EMI is defined as the time interval between the first deflection on the surface ECG and the onset of local myocardial shortening, as measured by 2D-speckle tracking.3 Second parameter is the systolic peak strain value, the maximum negative strain value between pulmonary valve opening and closure.4 Timing of the pulmonary valve closure was assessed in the parasternal short-axis view by Doppler tracing of the RVOT. The last parameter included in this combined model is the post-systolic index, defined as the percentage of shortening occurring after closure of the pulmonary valve. This index is calculated by taking the postsystolic shortening as a percentage of the global peak longitudinal strain.4 By using cut-offs of the previously mentioned parameters, the three types are distinguished. Type I is a normal deformation pattern, as seen in healthy controls, characterized by an EMI ≤90 ms, systolic peak strain ≥|-20%| and ≤10% post-systolic shortening. Type II is characterized by delayed onset of shortening (>90ms), reduced systolic peak strain (<|-20%| and ≥|-10%|) and minor post-systolic shortening (>10%). Type III strain patterns are characterized by little or no systolic peak strain (<|-10%|), predominantly systolic stretching and major post-systolic shortening.4 Mechanical dispersion The method for obtaining the mechanical dispersion from echocardiographic deformation imaging has been elaborated previously.5,6 Speckle tracking of the endocardium was performed in the 3 apical views for the LV and in the apical 4-chamber view for the RV.5,7 The LV was divided in a 16-segment model and the RV in a 6-segment model. The operator manually adjusted incorrectly tracked segments, and excluded them in the case of subsequently failed tracking. As a derivative of the contraction duration, time to peak negative strain was defined as the time from first deflection in the QRS complex on surface ECG to maximum LV and RV shortening by strain. Mechanical dispersion was calculated as the standard deviation (SD) of the segmental time intervals from onset Q/R on the surface ECG to peak negative strain, and expressed in milliseconds. The LV mechanical dispersion (LVMD) was calculated over all 16 segments and the RV mechanical dispersion (RVMD) over 6 segments, retaining the septal segments.6 3
RkJQdWJsaXNoZXIy MTk4NDMw