Permanent pacemaker implantation after valve and arrhythmia surgery in patients with preoperative atrial fibrillation

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Recording of Pacing Stimulus Artifacts by Endovascular Defibrillation Lead Systems: Comparison of True and Integrated Bipolar Circuits

Background: The occurrence ICD undersensing of ventricular fibrillation due to the presence of a pacing stimulus artifact (PSA) is in part related to the amplitude of the artifact recorded on the ICD rate sensing circuit. There is little comparative data regarding PSA amplitude recorded by commercial ICD rate-sensing circuits.Purpose: To compare PSA amplitude recorded by commercial endovascular defibrillation leads utilizing integrated or true bipolar sensing circuits.Methods: Nineteen large (60–120 kg) pigs were utilized. Two different commercial endovascular defibrillation leads were evaluated, each with its distal tip located at the right ventricular apex: (1) Medtronic Transvene; and (2) CPI Endotak. Three different rate-sensing circuits were evaluated: (1) Transvene true bipolar (tip-ring); (2) Transvene integrated bipolar (tip-coil); and (3) Endotak integrated bipolar (tip-coil). Using a separate pacing lead located at the left ventricular apex (n = 19 animals) or right ventricular outflow tract (n = 10 animals), pacing was performed at a pulse width of 0.5 milliseconds at outputs of 1.5, 5 and 10 volts. PSA amplitude was recorded at each output by each circuit.Results: During pacing from the left ventricular apex, at each pacing output voltage the PSA amplitude recorded by the true bipolar circuit (0.6 ± 0.1 mV at 1.5 volts, 2.0 ± 0.5 mV at 5 volts, 3.7 ± 0.8 mV at 10 volts) was significantly smaller than recorded by the Transvene integrated circuit (1.4 ± 0.3 mV at 1.5 volts, 3.8 ± 0.7 mV at 5 volts, 4.1 ± 0.8 mV at 10 volts) or the Endotak integrated circuit (1.8 ± 0.4 mV at 1.5 volts, 4.2 ± 1.0 mV at 5 volts, 6.3 ± 1.8 mV at 10 volts). During pacing from the right ventricular outflow tract, at each pacing output voltage the PSA amplitude recorded by the true bipolar circuit (0.7 ± 0.1 mV at 1.5 volts, 1.7 ± 0.4 mV at 5 volts, 4.0 ± 0.7 mV at 10 volts) was significantly smaller than recorded by the Transvene integrated circuit (1.1 ± 0.4 mV at 1.5 volts, 3.9 ± 1.2 mV at 5 volts, 7.5 ± 1.8 mV at 10 volts) or the Endotak integrated circuit (1.6 ± 0.7 mV at 1.5 volts, 4.3 ± 1.7 mV at 5 volts, 7.5 ± 2.6 mV at 10 volts). For both pacing sites, the PSA amplitude recorded by the two integrated circuits was not significantly different.Conclusions: For a given pacing output voltage, PSA amplitude recorded by commercial endovascular rate sensing/defibrillation leads is greater when the sensing circuit is integrated than when it is true bipolar. These data may be helpful in planning ICD implantation in patients with previously implanted permanent pacemakers.     

Remodeling of sinus node function after catheter ablation of right atrial flutter

INTRODUCTION: The purpose of this study was to investigate the effect of ablation of right atrial flutter upon sinus node function in humans. METHODS AND RESULTS: This study enrolled 35 patients. Twenty-four patients (16 men and 8 women; age 68 +/- 11 years) were referred for ablation of persistent atrial flutter (duration 8 +/- 11 months). After ablation, there was abnormal sinus node function defined as a corrected sinus node recovery time (CSNRT) > or = 550 msec. The control group consisted of 11 patients who were undergoing pacemaker implantation for sinus node disease but did not have a history of atrial dysrhythmias or ablation. Within 24 hours of ablation or pacemaker implantation, baseline maximal CSNRT was measured through a permanent pacemaker by AAI pacing at six cycle lengths: 600, 550, 500, 450, 400, and 350 msec. CSNRT then was measured in the same manner at 48 hours, 14 days, and 3 months after ablation/pacemaker implantation. P wave amplitude and duration, and percent atrial sensing also were assessed at the same intervals. For patients undergoing atrial flutter ablation, there was progressive temporal recovery of CSNRT (1,204 +/- 671 msec at baseline vs 834 +/- 380 msec at 3 months; P < 0.001) and a significant increase in the percent atrial sensing and P wave amplitude at 3 months compared with baseline (P < 0.001). In control subjects, there was no change in the CSNRT, percent atrial pacing, or P wave amplitude. CONCLUSION: After ablation of persistent atrial flutter, there is temporal recovery of CSNRT and increase in spontaneous atrial activity. These findings suggest that atrial flutter induces reversible changes in sinus node function.     

Pacemaker infection due to Aspergillus: report of two cases and literature review

BACKGROUND: Aspergillus infections of pacing systems are extremely uncommon, and most cases reported are characterized by an aggressive behavior that may lead to death of the patient. HYPOTHESIS: The study was undertaken to assess the incidence of pacemaker infection due to Aspergillus in a defined population. METHODS: A retrospective review of the case histories of all patients who underwent pacemaker implantation in the reference center for a defined population over a 13-year period was undertaken. A literature review of pacemaker infections due to Aspergillus was conducted. RESULTS: Of the 1,321 patients who required pacemaker implantation at Hospital Xeral-Calde in the Lugo region of northwestern Spain, 38 suffered a pacemaker infection. A pacemaker pocket infection due to Aspergillus fumigatus was found in two patients. Both patients had a previous history of diabetes mellitus. Cultures from pacemaker pocket inflammatory fluid yielded positive results. Following pacemaker explantation and antifungal therapy, clinical improvement was achieved. A literature review showed another five cases of pacemaker infection due to Aspergillus. However, two peculiarities were found in our patients: In both cases an etiological diagnosis was achieved prior to surgery and, to the best of our knowledge, they also constitute the first cases of pacemaker pocket infection due to Aspergillus. CONCLUSION: Although pacemaker infections due to Aspergillus species are uncommon, they should be considered in immunocompromised patients.     

起搏预防和终止快速性房性心律失常的疗效观察(附3例报告)

观察AT501起搏器起搏预防和终止快速性房性心律失常的疗效。3例病窦综合征(SSS)患者,同时伴有快速性房性心律失常,置入Medtronic公司生产的AT501起搏器,术后1个月打开三种独立的起搏预防治疗功能和3个可程控的起搏终止治疗功能。经8～10个月的随访,患者的临床症状较术前明显改善,通过9790程控仪回顾心律失常发生事件,发现AT501起搏器对快速性房性心律失常的检测准确率为98%,起搏预防治疗功能和起搏终止治疗功能可减少快速性房性心律失常的发作,其中起搏终止治疗的成功率为56%,在270～360ms快速性房性心律失常检测区成功率为78%,在220～270ms快速性房性心律失常检测区成功率为40%。结论:初步临床应用表明,AT501起搏器置入后通过对起搏器的起搏预防和终止治疗功能合理程控,可安全、有效地减少快速性房性心律失常的发作。