• 2018-07
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  • br Conclusions br Funding sources br


    Funding sources
    Conflict of interest
    Introduction Complex fractionated atrial electrograms (CFAEs) derived from time domain analysis and dominant frequency (DF) identified by fast Fourier transform (FFT) spectral analysis are widely used electrical parameters for understanding the initiation and perpetuation of atrial fibrillation (AF) [1–7]. CFAEs are now considered to reflect simply (1) dyssynchronous activation of separate cell groups at pivot points, (2) wave collision, far-field potentials, (3) critical zones of repetitive activations of AF driver(s), or (4) local reentry circuits [1–5], whereas high DF is reported to be related to the center of a focal-firing rotor or local reentry circuit [6,7]. Clinically, CFAE and/or high-DF sites have been demonstrated as effective targets for AF termination, suggesting their importance in the maintenance of AF [1–7]. Nonetheless, the pathogenesis of CFAE and DF are not fully understood. Adenosine triphosphate (ATP) is known to promote AF by shortening the atrial Phos-tag duration and refractory period [8–10]. In patients with paroxysmal AF (PAF), ATP infusion increases DF, particularly at the pulmonary vein (PV)–left atrial (LA) junction. DF is higher in patients with persistent AF (PerAF) than in patients with PAF at all the LA regions surveyed, but the extent of the DF increase with ATP is less in PerAF patients than that in PAF patients. Our preliminary results suggest that the ability of ATP to highlight sites driving PAF that could be targeted for ablation, whereas non-PV locations are more likely. Jadidi et al. reported [11] that atrial fibrosis as defined by delayed enhanced magnetic resonance imaging is associated with slower and organized electrical activity but lower voltage than healthy atrial sites in patients with long-lasting PerAF. Therefore, PerAF patients in the present study may represent electrical remodeling as demonstrated by higher DF and structural remodeling as shown by lower responses to ATP infusion, possibly due to patchy fibrosis around higher DF sites. In such cases, PV isolation plus LA ablation targeted at rotors in the LA body might be necessary. We therefore hypothesized that ATP may spatially affect the atrial electrogram interval determined by time domain and frequency domain analyses during AF. We investigated the effects of ATP on the atrial electrogram interval and DF characteristics in human AF, and evaluated whether these effects are influenced by the progression of atrial remodeling.
    Material and methods
    Conflict of interest
    Introduction Scoliosis forms a complex curve in all three planes, not only in the coronal plane, leading to deformities caused by the self-rotating movement of the spine [1]. Spinal anomalies may impair cardiorespiratory function.
    Case report A 62-year-old man visited our emergency department complaining of palpitations. His Cobb angle was over 50°, indicating severe scoliosis [Fig. 1(A)]. He was diagnosed with paroxysmal AF, and the heart rhythm was restored to normal by defibrillation. We planned to perform catheter ablation on an outpatient basis. We performed the Brockenbrough method safely under CT guidance, but an ordinary radiofrequency (RF) needle (Japan Lifeline Co.) was unsuitable for the patient. Normally, the Brockenbrough needle is positioned posterior to the septum at approximately 5 o’clock, but CT had shown that the patient’s heart was rotated clockwise from the usual position. The needle was curved and positioned at 4 o’clock in this case [Fig. 1(B)]. After transseptal puncture, we obtained an X-ray image of the left atrium (LA) following injection of a radiopaque dye. CT performed prior to the procedure was integrated into the 3-dimensional (3D) reconstruction electromechanical map of the patient’s atrium (EnSite® NavX®, St. Jude Medical Inc. St. Paul, Minnesota, USA). The 3D map also showed abnormal position and clockwise rotation of the heart: both the LA and RA were rotated clockwise. The anatomical relationship between the esophagus and pulmonary vein is shown in Fig. 1(C). The right pulmonary vein was difficult to isolate because there was insufficient space for manipulating the ablation catheter near the right pulmonary vein [Fig. 2(A)]. The ablation catheter was positioned slightly differently in the RA isthmus [Fig. 2(B)]; however, we successfully performed extensive encircling pulmonary vein isolation and ablation of the RA isthmus without any complications, using enhanced CT and 3D mapping [Fig. 2(C) and (D)].
    Discussion This is the first case report to describe AF ablation in a patient with scoliosis. AF ablation with scoliosis required extra precautions with respect to the anatomical position, based on data obtained by CT. The superimposition of pre-acquired CT/magnetic resonance imaging (MRI) images onto the electroanatomic 3D reconstruction is associated with an improved clinical outcome in AF ablation procedures [2]. 3D-CT fusion images provide an excellent overview of the morphology of the LA and pulmonary vein, thereby enhancing the safety of the AF ablation procedures [3].