Accurate diagnosis of syncope is essential because it ranges from cardiac syncope with a very poor prognosis to neurally-mediated syncope (NMS) with a relatively favorable prognosis. Diagnosis of syncope, however, is difficult in many patients even by HUT, so a new loading method for HUT or implanted Holter ECG monitoring will be required in the future. The prognosis of NMS itself may be favorable, but it may cause the aggravation of complications.

View full abstract

To verify the susceptibility of ventricle to arrhythmia after bone marrow mononuclear cell transplantation (BMMNCT), we measured ventricular fibrillation threshold (VFT) and monophasic action potential duration (MAPD₉₀). Lewis rats with doxorubicin-induced cardiomyopathy were divided into 2 groups: transplantation group (D–TX: BMMNC (1×10⁶) given transplants into the apex at 4 weeks after doxorubicin administration) and non-transplantation group (D–N). Age-matched normal group (N–N) was prepared. At 4 weeks after BMMNCT, the following electrophysiologic tests were performed. Experiment 1 (VFT): Two stainless wires were placed at the apex and a single train of 10 square wave stimuli was delivered across T wave. The lowest current developing ventricular fibrillation was determined as VFT. Experiment 2 (MAPD₉₀): The catheter was inserted into the left ventricle and pressed against the endocardium near the apex under regular cycle lengths. Experiment 1: VFT of D–TX and D–N were significantly lower than that of N–N (p<0.01). There was no difference between D–TX and D–N. Experiment 2: MAPD₉₀ of each group was lined up in length D–N > D–TX > N–N at every cycle lengths. There was a significant difference between D–N and N–N (p<0.01), and D–TX and N–N (p<0.05). In this model, BMMNCT did not increase susceptibility to arrthythmia.

View full abstract

Introduction: Although the atrial fibrillation cycle length (FCL) is considered to shorten in persistent atrial fibrillation (AF) as a result of electrical remodeling, whether a long-term change remains in FCL in patients with left ventricular (LV) dysfunction is uncertain. Morphological properties of AF waves were analyzed in patients with dilated cardiomyopathy (DCM). Methods and Results: The study population consisted of 43 patients with persistent AF, and they were divided into a DCM group (n=14) and a control group (n=29). Fibrillation waves from surface ECG lead V1 were purified by subtracting the QRS-T complex template. Power spectral analysis was performed by Fast Fourier Transformation, and the mean FCL was determined by the peak power frequency in 20 epochs at each recording. The LV ejection fraction was lower in the DCM group (50±18%) than the control (63±8%, p=0.001). The mean FCL was shorter in the DCM group (132±14 ms) than the control (151±23 ms, p=0.007) and there was a significant correlation between the FCL and LV dimensions (p=0.03). Conclusion: In patients with persistent AF and LV dysfunction, FCL was shorter in comparison with the control, and seemed to be influenced by LV dimensions.

View full abstract

Background: It is sometimes difficult to differentiate the transient appearance of atrial fibrillation (AF) after pulmonary vein (PV) isolation from a true recurrence of AF. We attempted to differentiate them by analyzing the time course after the procedure.
Methods and Results: 79 patients who underwent PV isolation were divided into two groups (successful: N=60 and unsuccessful: N=19) according to the final outcome. Antiarrhythmic drugs were used either temporarily or continuously to treat re-appearance of AF after the procedure. The transient appearance of AF in the successful group gradually faded, while true AF recurrence in the unsuccessful group consistently increased in line with the follow-up (F/U) period. The appearance of AF after 3 months predicted a subsequent failure of the procedure with a positive/negative predictive value of 87/90%, respectively.
Conclusion: Since the transient appearance of AF decreased and the true recurrence of AF increased in line with the F/U period, we should therefore wait at least 3 months before judging the outcome of PV isolation.

View full abstract

This study evaluated the efficacy of the left atrial Maze procedure (Lt-maze) and unipolar radiofrequency (RF) ablation as an additional procedure for the surgical treatment of atrial fibrillation (AF) in patient with other cardiac disease.
Methods and Results: The Maze procedure was performed in 100 consecutive patients with AF: Lt-maze, 71 patients; bi-atrial Maze (Bi-maze), 29 patients. Cryoablation and RF ablation were used in 82 and 18 patients, respectively. There were no in-hospital or early deaths. Fourteen patients (14%) experienced postoperative complications. Seventy-five patients (75%) were in sinus rhythm (SR) at discharge, 4 patients were in junctional rhythm, and 21 patients had AF. Two patients (2%) required permanent pacemaker implantation. The AF-free rate at discharge was 79%, and the AF-free rate at hospital discharge did not differ significantly between cryoablation and unipolar RF ablation (78% and 82%, respectively). There were no significant differences between these two groups in operative results, in terms of the aortic cross-clamp time, cardiopulmonary bypass time, and AF-free rate, with the AF-free rate not differing significantly in those who received single valve surgery (73% and 75% in the cryoablation and unipolar RF ablation groups, respectively). The equipment cost of the two procedures differed greatly: 14,000 yen/patient for cryoablation and 250,000 yen/patient for RF ablation. The AF-free rate did not differ significantly between Lt-maze (76%) and Bi-maze (86%), including in those who received single valve surgery (72% and 79%, respectively). The significant predictors of AF recurrence in a univariate analysis were left atrial diameter (p=0.03), duration of AF (p<0.01), fibrillation amplitude on ECG (p=0.02), and cardiothoracic ratio (p<0.01), with the duration of preoperative AF being the only significant predictor of AF in a multivariate analysis.
Conclusion: In this series, unipolar RF ablation for the Maze procedure was as effective as cryoablation at eliminating AF, and Lt-maze and Bi-maze were equipotent at restoring SR at discharge.

View full abstract

The extrathoracic subclavian venous approach is a new approach with the aim to exclude the disadvantages of the conventional subclavian venous approach that carries a risk of pneumothorax and may result in lead damage. We investigated long-term survival of the leads implanted by this new approach between May 1995 and June 2005. A total of 482 leads implanted in 309 patients were analyzed. In cases of patient death, meeting criteria for lead failure or difficulty of continuing follow-up for other reasons, the follow-up was terminated at that time. Therefore, the follow-up was complete for 358 leads (74.3%) and the mean follow-up time was 55.0±32.1 months (range 1–122 months). The overall lead survival rate was 100% at 5 years and 98.3% at 7 years. This finding suggested that this approach might reduce the incidence of lead failure.

View full abstract

Herein we report a case of a patient presenting with paroxysmal atrial fibrillation (PAF) in whom the pulmonary veins (PVs) had a common inferior trunk and PV isolation at the common inferior trunk was successfully performed to prevent recurrence of PAF. A 58-year-old man with drug-resistant PAF was referred to undergo curative treatment at our institution. A three-dimensional image of the PVs re-constructed by contrast-enhanced multi-detector computed tomography before the operation revealed a common inferior trunk of the PVs (24-mm diameter). Segmental ostial PV isolation with the guidance of a circular mapping catheter was performed for both superior PVs and the common inferior PV trunk. All three PV ostia were successfully isolated from the LA, and the patient has been free from PAF thereafter for 18 months. Preprocedural multi-detector computed tomography or magnetic resonance imaging to evaluate the anatomy of PVs (the number, size, and shape) is thus considered to be useful for performing safe and smooth catheter ablation in patients with PAF.

View full abstract

Myocardial perforation by a pacing lead occurred 12 days after implantation. The lead was propelled into the myocardium of the anterior wall of ventricles without passing through the left ventricular cavity, and finally protruded into the pericardial cavity. Computed tomography of the chest was helpful for confirming the perforation by the pacing lead.

View full abstract