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A Randomized Double‐Blind, Cross‐Over Study of the Linear and Nonlinear Algorithms for the QT Sensing Rate Adaptive Pacemaker
Author(s) -
BAIG M.W.,
GREEN A.,
WADE G.,
KOVANCI E.,
CONSTABLE P.D.L.,
PERRINS E.J.
Publication year - 1990
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1990.tb06894.x
Subject(s) - medicine , heart rate , anaerobic exercise , algorithm , cardiology , linear acceleration , nonlinear system , acceleration , blood pressure , mathematics , physical therapy , physics , classical mechanics , quantum mechanics
BAIG, M.W., ET AL.: A Randomized Double‐Blind, Cross‐Over Study of the Linear and Nonlinear Algorithms for the QT Sensing Rate Adaptive Pacemaker. We have compared the pacing rate responses during cardiopulmonary exercise testing in 11 patients (mean 59 years, six female) with implanted QT sensing rate adaptive pacemakers who were randomly programmed to 1‐month periods in the linear and nonlinear algorithms using a double‐blind, cross‐over design. Exercise testing was performed at the end of each month block and symptoms were scored with the MacMaster questionnaire. With exercise, the time to a 10 beats/min increment in rate was significantly less with the nonlinear compared to the linear algorithm (126 sec vs 255 sec, P = 0.02) but there were no significant differences in exercise duration, the peak pacing rate, the peak VO 2 , the VO 2 at the anaerobic threshold or the mean correlation coefficients of the pacing rate VO 2 relationship. Rate oscillation occurred in seven patients in the linear algorithm and in two patients in the nonlinear setting. Initial deceleration of the pacing rate at the onset of exercise occurred in seven patients in the linear algorithm and in four patients in the nonlinear setting. The nonlinear algorithm is associated with a faster response time during exercise and fewer instances of rate instability. However, it has not overcome the problem of a dip in the pacing rate at the beginning of exercise. The major difference in the function of the two algorithms is faster initial acceleration with the nonlinear algorithm. This is explained by the significantly higher values of the slope setting at the lower rate limit for the nonlinear versus the linear algorithm (6.3 ms/ms vs 5.1 ms/ms).