Aiming at the nonlinear system identification problem, a parallel recursive affine projection (AP) adaptive algorithm for the nonlinear system based on Volterra series is presented in this paper. The algorithm identifies in parallel the Volterra kernel of each order, recursively estimate the inverse of the autocorrelation matrix for the Volterra input of each order, and remarkably improve the convergence speed of the identification process compared with the NLMS and conventional AP adaptive algorithm based on Volterra series. Simulation results indicate that the proposed method in this paper is efficient.

Objective To explore the baseline echocardiographic characteristics and the time course and recovery of left ventricular systolic function in patients with tachycardia-induced cardiomyopathy. Methods Fif-teen patients received radiofrequency cather ablation for tachycardiarrhymias from November 2012 to April 2017 were screened in this study.All 15 patients were examined by intracardiac electrophysiology and treated by RFCA under the guidance of three dimensional mapping system.All Patients received transthoracic echocardiography for 3-month follow-up.Levels of NT-proBNP before and after the ablation were compared. Results Successful abla-tion was performed in 14 of 15 patients. There was significant improvement in left ventricular ejection fraction (35.33 ± 6.11 vs. 57.93 ± 9.38%;P < 0.001). The LVEDD after treatment had significant differences(55.47 ± 8.06 vs.49.87 ± 8.99 P<0.001)after 3-month follow-up;the LAD after treatment decreased significantly(38.87 ± 3.27 mm vs. 35.20 ± 2.46;P < 0.001)and the levels of NT-proBNP decreased after ablation from 3 474.07 ± 3 400.59 pg/mL to 497.33 ± 437.84 pg/mL(P = 0.005). Conclusions Restoration of left ventricular systolic func-tion and reversal of LV remodeling can be achieved with successful elimination of tachycardia in the majority of pa-tients.NT-proBNP level elevates in subjects with TCM and decreases sharply after ablation.