Fractures of pace-sense electrodes in implantable cardioverter-defibrillator patients are a common cause of inappropriate shocks. To reduce inappropriate shocks, we developed a lead-integrity alert (LIA) triggered by either oversensing or high impedance that can be downloaded into previously implanted implantable cardioverter-defibrillators. This prospective study tested the hypothesis that the LIA would reduce the percentage of patients who receive inappropriate shocks compared with a concurrent control group monitored by impedance only. Each group included a prospectively determined sample size of 213 consecutive patients with fractures confirmed by structural analysis of explanted leads. The LIA group had a 46% relative reduction (95% confidence interval 34% to 55%) in the percentage of patients with ≥1 inappropriate shock (LIA 38% versus control 70%, P <0.001) and a 50% relative reduction (95% confidence interval 33% to 61%) in the percentage with ≥5 shocks (25% versus 50%, P <0.001). These data show that a software download that upgrades previously implanted implantable cardioverter-defibrillators without surgical revision reduces inappropriate shocks caused by lead fractures. See p 1449. Twin-twin transfusion syndrome is an important cause of perinatal mortality in monochorionic twins, often because of cardiovascular compromise associated with increased intravascular volume in the recipient twin. In this autopsy study of 11 sets of twins with the condition, 4 recipient twins had anomalous mitral arcade, a rare fibrotic valve lesion that is associated with regurgitation. Previously unrecognized in twin-twin transfusion syndrome, anomalous mitral arcade may explain many of the progressive hemodynamic abnormalities in this condition. From this retrospective clinicopathological correlation study, ultrasound/echocardiographic evidence of left atrial dilation and significant mitral regurgitation in the recipient should raise suspicion for anomalous mitral arcade, a structural lesion that likely will not reverse after successful laser treatment or delivery of the fetus, as other hemodynamic and functional abnormalities often do. Thus, for perinatologists …
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