Pacemaker and ICD Troubleshooting

Continuous advancements in technology and software algorithms for pacemakers and implantable cardioverter‐defibrillators (ICDs) have improved functional reliability and broadened their diagnostic capabilities. At the same time, understanding management and troubleshooting of modern devices has become increasingly complex for the device implanter. This chapter provides an overview of the underlying physics and basic principles important to pacemaker and ICD function. The second part of this chapter outlines common device problems encountered in patients with pacemakers and ICDs and provides solutions and tips for troubleshooting

Time-to-effect guided pulmonary vein isolation utilizing the third-generation versus second generation cryoballoon: One year clinical success

Background: The second-generation cryoballoon (CB2) provides effective and durable pulmonary vein isolation (PVI) associated with encouraging and reproducible clinical outcome data. The latest- -generation cryoballoon (CB3) incorporates a 40% shorter distal tip, thus allowing for an increased rate of PVI real-time signal recording and facilitating individualized ablation strategies taking the time-to- -effect (TTE) into account. However, whether this characteristic translates into favorable clinical success has not been evaluated yet. Herein was investigated 1-year clinical success after CB3 in comparison to CB2 based-PVI. Methods: One hundred and ten consecutive patients with paroxysmal or short-standing persistent atrial fibrillation (AF) underwent CB2 (n = 55 patients) -or CB3 (n = 55 patients) -based PVI. The freeze-cycle duration was set to TTE + 120 s if TTE could be recorded, otherwise a fixed freeze-cycle duration of 180 s was applied. Results: A total of 217/218 (99%, CB3) and 217/217 (100%, CB2) pulmonary veins (PV) were successfully isolated. The real-time PVI visualization rate was 69.2% (CB3) and 54.8% (CB2; p = 0.0392). The mean freeze-cycle duration was 194 ± 77 s (CB3) and 206 ± 85 s (CB2; p = 0.132), respectively. During a median follow-up of 409 days (interquartile range [IQR] 378–421, CB3) and 432 days (IQR 394–455, CB2) 73.6% (CB3) and 73.1% of patients (CB2) remained in stable sinus rhythm after a single procedure (p = 0.806). Conclusions: A higher rate of real-time electrical PV recordings was seen using the CB3 as compared to CB2. There was no difference in 1-year clinical follow-up

Association of atrial tissue fibrosis identified by delayed enhancement MRI and atrial fibrillation catheter ablation: the DECAAF study

IMPORTANCE: Left atrial fibrosis is prominent in patients with atrial fibrillation (AF). Extensive atrial tissue fibrosis identified by delayed enhancement magnetic resonance imaging (MRI) has been associated with poor outcomes of AF catheter ablation. OBJECTIVE: To characterize the feasibility of atrial tissue fibrosis estimation by delayed enhancement MRI and its association with subsequent AF ablation outcome. DESIGN, SETTING, AND PARTICIPANTS: Multicenter, prospective, observational cohort study of patients diagnosed with paroxysmal and persistent AF (undergoing their first catheter ablation) conducted between August 2010 and August 2011 at 15 centers in the United States, Europe, and Australia. Delayed enhancement MRI images were obtained up to 30 days before ablation. MAIN OUTCOMES AND MEASURES: Fibrosis quantification was performed at a core laboratory blinded to the participating center, ablation approach, and procedure outcome. Fibrosis blinded to the treating physicians was categorized as stage 1 (<10% of the atrial wall), 2 (≥10%-<20%), 3 (≥20%-<30%), and 4 (≥30%). Patients were followed up for recurrent arrhythmia per current guidelines using electrocardiography or ambulatory monitor recording and results were analyzed at a core laboratory. Cumulative incidence of recurrence was estimated by stage at days 325 and 475 after a 90-day blanking period (standard time allowed for arrhythmias related to ablation-induced inflammation to subside) and the risk of recurrence was estimated (adjusting for 10 demographic and clinical covariates). RESULTS: Atrial tissue fibrosis estimation by delayed enhancement MRI was successfully quantified in 272 of 329 enrolled patients (57 patients [17%] were excluded due to poor MRI quality). There were 260 patients who were followed up after the blanking period (mean [SD] age of 59.1 [10.7] years, 31.5% female, 64.6% with paroxysmal AF). For recurrent arrhythmia, the unadjusted overall hazard ratio per 1% increase in left atrial fibrosis was 1.06 (95% CI, 1.03-1.08; P < .001). Estimated unadjusted cumulative incidence of recurrent arrhythmia by day 325 for stage 1 fibrosis was 15.3% (95% CI, 7.6%-29.6%); stage 2, 32.6% (95% CI, 24.3%-42.9%); stage 3, 45.9% (95% CI, 35.5%-57.5%); and stage 4, 51.1% (95% CI, 32.8%-72.2%) and by day 475 was 15.3% (95% CI, 7.6%-29.6%), 35.8% (95% CI, 26.2%-47.6%), 45.9% (95% CI, 35.6%-57.5%), and 69.4% (95% CI, 48.6%-87.7%), respectively. Similar results were obtained after covariate adjustment. The addition of fibrosis to a recurrence prediction model that includes traditional clinical covariates resulted in an improved predictive accuracy with the C statistic increasing from 0.65 to 0.69 (risk difference of 0.05; 95% CI, 0.01-0.09). CONCLUSIONS AND RELEVANCE: Among patients with AF undergoing catheter ablation, atrial tissue fibrosis estimated by delayed enhancement MRI was independently associated with likelihood of recurrent arrhythmia. The clinical implications of this association warrant further investigation

Phrenic Nerve Injury During Cryoballoon-Based Pulmonary Vein Isolation: Results of the Worldwide YETI Registry.

BackgroundCryoballoon-based pulmonary vein isolation (PVI) has emerged as an effective treatment for atrial fibrillation. The most frequent complication during cryoballoon-based PVI is phrenic nerve injury (PNI). However, data on PNI are scarce.MethodsThe YETI registry is a retrospective, multicenter, and multinational registry evaluating the incidence, characteristics, prognostic factors for PNI recovery and follow-up data of patients with PNI during cryoballoon-based PVI. Experienced electrophysiological centers were invited to participate. All patients with PNI during CB2 or third (CB3) and fourth-generation cryoballoon (CB4)-based PVI were eligible.ResultsA total of 17 356 patients underwent cryoballoon-based PVI in 33 centers from 10 countries. A total of 731 (4.2%) patients experienced PNI. The mean time to PNI was 127.7±50.4 seconds, and the mean temperature at the time of PNI was -49±8°C. At the end of the procedure, PNI recovered in 394/731 patients (53.9%). Recovery of PNI at 12 months of follow-up was found in 97.0% of patients (682/703, with 28 patients lost to follow-up). A total of 16/703 (2.3%) reported symptomatic PNI. Only 0.06% of the overall population showed symptomatic and permanent PNI. Prognostic factors improving PNI recovery are immediate stop at PNI by double-stop technique and utilization of a bonus-freeze protocol. Age, cryoballoon temperature at PNI, and compound motor action potential amplitude loss >30% were identified as factors decreasing PNI recovery. Based on these parameters, a score was calculated. The YETI score has a numerical value that will directly represent the probability of a specific patient of recovering from PNI within 12 months.ConclusionsThe incidence of PNI during cryoballoon-based PVI was 4.2%. Overall 97% of PNI recovered within 12 months. Symptomatic and permanent PNI is exceedingly rare in patients after cryoballoon-based PVI. The YETI score estimates the prognosis after iatrogenic cryoballoon-derived PNI. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03645577. Graphic Abstract: A graphic abstract is available for this article