title: Impact of programmed sensitivity safety factor on atrial sensing in children.
abstract: The relationship between the pacemaker sensitivity safety factor (PSSF) and atrial under- or oversensing as documented by 24-hour Holter monitoring was examined. Our study comprised 78 transvenous fixed atrial leads implanted between 1983-1995 in 71 children. Overall, 210 Holter reports identified 143 (68%) Holters with normal atrial sensing function, 31 (15%) with undersensing, 32 (15%) with oversensing, and 4 (2%) with both problems. From 161 Holter reports in which the PSSF was available, the incidence of undersensing at a PSSF of 2.0 (range 1.5-2.4) was 25% (14/57). There was a dramatic decline in undersensing when the PSSF was > or = 3 (3%) compared to a PSSF < 3 (21%) (P < 0.001). A PSSF cut-off point of 2.0 best predicted occurrence of undersensing with a sensitivity of 79% and a specificity of 67%. Other variable were also examined by multiple logistic regression analysis, but only PSSF remained highly associated with undersensing (odds ratio [OR] = 0.6, P = 0.03). In contrast, PSSF did not have a significant role in predicting oversensing, but presence of sick sinus syndrome (OR = 10.5) or unipolar lead (OR = 5.6) were significantly associated with oversensing (P = 0.0001). The majority of undersensing problems can be avoided by routinely allowing for at least a threefold or more programmed sensitivity margin. Other factors may increase the risk of oversensing, regardless of the PSSF.
authors.affiliation: Division of Cardiology, Hospital for Sick Children, Toronto, Canada.
authors.forename: C C
authors.initials: CC
authors.lastname: Chiu
authors.forename: R M
authors.initials: RM
authors.lastname: Gow
authors.forename: B W
authors.initials: BW
authors.lastname: McCrindle
authors.forename: R M
authors.initials: RM
authors.lastname: Hamilton
mesh_terms: D002648:Child; D015716:Electrocardiography, Ambulatory; D004867:Equipment Design; D004868:Equipment Failure; D006327:Heart Block / Q000175:diagnosis / Q000628:therapy*; D006801:Humans; D016015:Logistic Models; D010138:Pacemaker, Artificial; D012372:ROC Curve; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012804:Sick Sinus Syndrome / Q000175:diagnosis / Q000628:therapy*