Sayuki Kobayashi

The influence of the external structures in atrial fibrillation patients: Relationship to focal low voltage areas in the left atrium.

INTRODUCTION Left atrial (LA) low voltage areas (LVAs) are suggested as an important factor for maintaining atrial fibrillation (AF). The relationship between focal LVAs and anatomical contact is still unclear. METHODS Thirty paroxysmal AF (PAF) and 30 persistent AF (PsAF) patients underwent high density voltage mapping during sinus rhythm before any radiofrequency applications were performed. The relationship between the LVA (<0.5mV) and contact area (CoA) demonstrated by enhanced CT and the distance to near external structures were investigated. RESULTS The anterior region, posterior wall and left pulmonary vein (LPV) antrum were the three most frequent LVA sites that corresponded to CoA sites, and LVAs mostly overlapped with CoAs (PAF 47/61: 77%, PsAF 63/74: 85%). In the PAF group, patients with posterior-LVAs had a shorter distance to the vertebrae than those without (2.8 ± 1.1 vs. 4.4 ± 1.9 mm; P=0.0086). The distance to the vertebrae was the only predictive factor of the existence of a posterior-LVA and the cut-off value was ≤2.9 mm (P<0.0001). Similarly, an LPV-LVA also had the same results (2.0 ± 0.5 vs. 2.7 ± 0.8mm, P=0.0127) and the cut-off value was ≤2.6mm (P=0.0391). In contrast, the PsAF patients had no difference in the distance when compared to the existence of an LVA. CONCLUSIONS Anatomical CoAs demonstrated a spatial relationship to the LVAs in AF patients. In PAF patients, the distance to near external structures in the posterior region was a predictive factor for the existence of an LVA and may have had some influence on maintaining AF, while in PsAF patients no relationship was suggested.

Epicardial adipose tissue-based defragmentation approach to persistent atrial fibrillation: Its impact on complex fractionated electrograms and ablation outcome

BACKGROUND Increased epicardial adipose tissue (EAT) volume is associated with atrial fibrillation (AF). However, the efficacy of EAT-based left atrial (LA) ablation for persistent AF (PsAF) is unclear. OBJECTIVE The purpose of this study was to assess whether EAT-based LA ablation is effective for PsAF. METHODS In 60 PsAF patients (group I), 3-dimensional reconstructed computed tomography images depicting EAT were merged with NavX-based dominant-frequency (DF) and complex fractionated electrogram (CFE) maps obtained during AF. Pulmonary vein antrum isolation (PVAI) was followed by map-guided EAT-based ablation. Results were compared to those in a historical control group (group II, case-matched patients who underwent generalized stepwise ablation including linear plus CFE-targeted ablation). RESULTS In 70% (n = 42) of group I patients, the LA-EAT was located at the pulmonary vein antra; anterior and inferior surfaces, roof, septum, and mitral annulus; and left atrial appendage. EAT was at or near (<3 mm) 71% (390/550) of high-DF (> -8 Hz) sites. In 41 patients with persistent AF despite EAT-targeted ablation, CFE burden decreased significantly (from 96% to 13%, P < .0001), and DF decreased within the coronary sinus (6.9 ± 0.7 Hz vs 5.9 ± 0.7 Hz, P < .0001). Radiofrequency energy duration was significantly less in group I than in group II (25 ± 6 minutes vs 31 ± 12 minutes, P < .05). During 16-month follow-up, freedom from AF on antiarrhythmic drugs was 78% vs 60% (P < .05). CONCLUSION PVAI plus EAT-based ablation efficiently eliminates high-frequency sources and yields relatively high success. EAT-based LA ablation is a simple, clinically feasible PsAF ablation strategy.

Impact of Insulin Resistance on Neointimal Tissue Proliferation after 2nd-Generation Drug-Eluting Stent Implantation

Percutaneous coronary intervention is established as an effective treatment for patients with ischemic heart disease; in particular, drug-eluting stent implantation is known to suppress in-stent restenosis. Diabetes mellitus is an independent risk factor for restenosis, so reducing insulin resistance is being studied as a new treatment approach. In this prospective study, we sought to clarify the factors associated with in-stent restenosis after percutaneous coronary intervention, and we evaluated the homeostasis model assessment of insulin resistance (HOMA-IR) index as a predictor of restenosis. We enrolled 136 consecutive patients who underwent elective percutaneous coronary intervention at our hospital from February 2010 through April 2013. All were implanted with a 2nd-generation drug-eluting stent. We distributed the patients in accordance with their HOMA-IR index values into insulin-resistant Group P (HOMA-IR, ≥2.5; n=77) and noninsulin-resistant Group N (HOMA-IR, <2.5; n=59). Before and immediately after stenting, we measured reference diameter, minimal lumen diameter, and percentage of stenosis, and after 8 months we measured the last 2 factors and late lumen loss, all by means of quantitative coronary angiography. After 8 months, the mean minimal lumen diameter was smaller in Group P than that in Group N (1.85 ± 1.02 vs 2.37 ± 0.66 mm; P=0.037), and the mean late lumen loss was larger (0.4 ± 0.48 vs 0.16 ± 0.21 mm; P=0.025). These results suggest that insulin resistance affects neointimal tissue proliferation after 2nd-generation drug-eluting stent implantation.

Strong modulation of ectopic focus as a mechanism of repetitive interpolated ventricular bigeminy with heart rate doubling

BACKGROUND Repetitive interpolated ventricular bigeminy (RIVB) can introduce a doubling of the ventricular rate. OBJECTIVE To clarify the mechanism of RIVB, we hypothesized that it was introduced by a strong modulation of the ventricular automatic focus. METHODS RIVB, defined as more than 7 bigeminy events, was detected by instantaneous heart rate and bigeminy interval (BI) tachograms in 1450 successive patients with frequent ventricular premature contractions (≥3000 per day). Postextrasystolic interval bigeminy interval curves were plotted to determine the degree of modulation. Mean sinus cycle length bigeminy interval curves were plotted for selection. RIVB was simulated by using a computer-based parasystole model. RESULTS RIVB was observed in 7 patients (age 60 ± 16 years; 2 men and 5 women) with a heart rate of 58.2 ± 6.5 beats/min during a rest period both during the day and at night. The tachograms disclosed the onset of the RIVB with a doubled ventricular rate to 112.3 ± 8.5 beats/min. On the postextrasystolic interval bigeminy interval curves, compensatory bigeminy and interpolated bigeminy constituted overlapping regression lines with slopes close to 1.00 and RIVB was located in the lower left portion. RIVB lasting for up to 3 hours was quickly detected by mean sinus cycle length bigeminy interval curve. The PQ interval immediately after RIVB was prolonged in comparison with baseline (0.18 ± 0.02 to 0.21 ± 0.02 seconds; P < .001). The simulation was able to reproduce RIVB faithfully at a slow heart rate. CONCLUSIONS Our findings support the hypothesis that RIVB was introduced by strongly modulated ventricular pacemaker accelerated by an intervening normal QRS.

Impact of catheter tip-tissue contact on three-dimensional left atrial geometries: Relationship between the external structures and anatomic distortion of 3D fast anatomical mapping and high contact force guided images.

BACKGROUND A high catheter tip-tissue contact force (CF) with the myocardium may cause 3-dimensional (3D) map distortion, however, the influence of external structures surrounding the left atrium (LA) on that distortion remains unknown. This study characterized the impact of high CF mapping on the local LA geometry distortion. METHODS Thirty AF patients underwent 3D-ultrasound merged with CT images (3D-Merge-CT). The LA area in contact with external structures was identified by enhanced CT. Fast-electroanatomical-mapping (FAM) geometries were created by two methods, point-by-point mapping with high (>10g) CFs (high-CF guided-FAM), followed by that with multielectrode-mapping catheters (conventional-FAM). The resulting geometries were compared with the 3D-Merge-CT images. RESULTS Three representative anatomical contact areas (ascending aorta-vs.-anterior wall, descending aorta-vs.-left pulmonary vein [PV], and vertebrae-vs.-posterior wall) were identified. The PV antrum distorted distance on the 3D-Merge-CT was significantly longer for high-CF guided-FAMs than conventional-FAMs (1.7[0-3.6] vs. 0[0-1.8]mm, P<0.0001). In high-CF maps, the distorted distance significantly differed between regions with and without contact areas in both the PV antrum (0[0-0.17] vs. 1.7[0-3.9]mm, P=0.0201) and LA body region (0[0-1.5] vs. 1.7[0.7-2.2]mm, P<0.005). The catheter tip-tissue CF did not correlate with the distorted distance (r=0.08, P=0.46), and a multivariate analysis revealed that the absence of anatomical contact areas was strongly associated with significant local distortion, independent of the CF. CONCLUSIONS High-CF guided mapping yields greater 3D-image anatomical distortion than conventional-FAM methods. That distortion was attenuated by regions with anatomical contact areas, suggesting that regional anatomic distortion is involved in the existence of external structures surrounding the LA.

Thrombosis in an Internal Jugular Vein and an Upper Limb Deep Vein Treated with Edoxaban

A 45-year-old man complained of swelling of the left side of his neck and left upper limb. Ultrasonography and enhanced computed tomography (CT) revealed thrombosis of the left internal jugular, subclavian, and brachiocephalic vein. Based on various examinations, the patient was diagnosed with idiopathic venous thrombosis early in his clinical course. There were no findings to suggest malignancy or abnormal coagulability. However, two months after the start of treatment, the patient was diagnosed with gastric cancer. Despite the presence of Trousseau syndrome, treatment with edoxaban (an oral anticoagulant), reduced the swelling dramatically without any bleeding complications.

Influence of the left atrial contact areas on fixed low-voltage zones during atrial fibrillation and sinus rhythm in persistent atrial fibrillation: NAKAHARA et al .

Atrial low‐voltage zones (LVZ) are suggested as important factors for maintaining persistent atrial fibrillation (PsAF). The relationship between LVZs and left atrial (LA) contact areas (CoAs) is still unclear.

Coved-type ST-elevation during ablation of ischemic ventricular tachycardia

A coved‐type electrocardiogram (ECG) change in Brugada syndrome is suggested to be the result of abnormally delayed depolarization over the right ventricular outflow tract; however, ischemia of the conus branch of the right coronary artery presents the same ECG change. A 63‐year‐old man with a history of myocardial infarction demonstrated a transient coved‐type ECG change during catheter ablation of ventricular tachycardia. The ECG change appeared during left ventricular mapping without any chest symptoms, and recovered spontaneously. A pilsicainide test was negative and a coved‐type ECG did not appear during the perioperative or follow‐up period.

Left-ventricular filling disturbances in cardiac amyloidosis: study of atrial sound and diastolic inflow velocities

Cardiac amyloidosis is characterized by left ventricular filling disturbances in a relatively early stage. To investigate such disturbances more precisely, we studied atrial sound and left ventricular inflow velocity patterns. Twelve cases diagnosed as cardiac amyloidosis according to the clinical criteria including rectal biopsies and serum amyloid proteins or at autopsy were reviewed and analyzed. Their mean age was 60.9 +/- 12.5 years. Twelve age-matched cases with hypertrophic cardiomyopathy (HCM) served as the controls. We measured the amplitude of atrial sound by low-frequency phonocardiograms and the ratio of the heights of the A wave of apexcardiograms (ACG) to the total amplitude of the ACG. The mitral inflow velocity patterns were recorded using pulsed Doppler echocardiography. The rapid filling wave (R), atrial filling wave (A) and the ratio of A to R (A/R) were measured. In the amyloidosis group, atrial sound moderately increased in 2 cases, it was faint in 9 and not manifest in the remaining one. The A wave in the amyloidosis group was significantly smaller than that in the HCM group (p < 0.001) (12.4 +/- 3.9 vs 22.4 +/- 5.6%). In the left ventricular inflow velocity patterns, the R in amyloidosis was smaller than that in HCM (41.7 +/- 16.0 vs 56.4 +/- 12.1 cm/sec) (p < 0.02). The A in amyloidosis was also smaller than that in HCM (40.5 +/- 13.4 vs 58.1 +/- 13.0 cm/sec) (p < 0.006). The A/R was 1.0 +/- 0.34 in amyloidosis and 1.1 +/- 0.32 in HCM (N.S.). Both A and R were significantly less in amyloidosis than those in HCM.(ABSTRACT TRUNCATED AT 250 WORDS)

Severe heart failure (NYHA Class IV) is associated with increased left ventricular mass index and short mitral deceleration time in severe aortic valve stenosis

In aortic valve stenosis (AS), congestive heart failure (CHF) is a well‐established symptom that indicates the need for surgical aortic valve replacement (SAVR). However, it is difficult to judge whether CHF symptoms such as dyspnea are caused by severe AS or other conditions, especially in elderly persons with restricted mobility or other organ complications. It is important to identify objective and noninvasive parameters associated with severe CHF symptoms in severe AS.