Hideki Okui

Control of catecholamine release and blood pressure with octreotide in a patient with pheochromocytoma: a case report with in vitro studies.

A 65-year-old male patient with pheochromocytoma, whose hypertensive episodes were uncontrolled using conventional therapy, was successfully treated with octreotide (SMS 201-995). The serum catecholamine level and the urinary excretion of catecholamines decreased after 300 μg/day of octreotide was administered. To clarify the mechanisms of octreotide that lower catecholamine released from a tumor, we studied the in vitro effects of octreotide on membrane potentials and voltage-dependent Ca2+ channel (VDCC) current using the whole-cell patch-clamp technique in single pheochromocytoma cells dispersed after tumor resection. The action potentials were reversibly inhibited with 10 μM octreotide. In addition, the VDCC current evoked by depolarized pulses from the holding potential of –60 mV was inhibited with 10 μM octreotide. Octreotide is useful for controlling blood pressure before surgery in some patients with uncontrolled hypertension caused by a pheochromocytoma.

Effect of Right Ventricular Apex Pacing on the Tei Index and Brain Natriuretic Peptide in Patients with a Dual‐Chamber Pacemaker

Background: Asynchronous electrical activation induced by right ventricular apex (RVA) pacing can cause various abnormalities in left ventricular (LV) function, particularly in the context of severe LV dysfunction or structural heart disease. However, the effect of RVA pacing in patients with normal LV and right ventricular (RV) function has not been fully elucidated. The aim of this study was to characterize the effects of RVA pacing on LV and RV function by assessing isovolumic contraction time and isovolumic relaxation time divided by ejection time (Tei index) and by assessing changes in plasma brain natriuretic peptide (BNP).

Relationship between clinical outcomes and unintentional pulmonary vein isolation during substrate ablation of atrial fibrillation guided solely by complex fractionated atrial electrogram mapping

BACKGROUND Controversy exists as to whether atrial fibrillation (AF) ablation guided solely by complex fractionated atrial electrogram (CFAE) has a good outcome despite not requiring pulmonary vein isolation (PVI). OBJECTIVES The purpose of this study was to evaluate the effectiveness of AF ablation guided solely by targeting CFAE areas, and to determine whether its clinical efficacy has any relationship with unintentionally isolating the PV. METHODS We studied 100 consecutive patients (ages 59 ± 11 years; 54 with paroxysmal, 35 persistent, and 11 long-standing persistent AF), who underwent CFAE-ablation. PV potential (PVP) was recorded before and after ablation. After excluding 39 patients in whom sinus rhythm could not be maintained before ablation by internal cardioversion and/or who had a history of PVI(s), PVPs were analyzed. RESULTS AF was terminated during ablation in 98% of paroxysmal, 80% of persistent, and 55% of long-standing persistent AF patients. Nifekalant (0.3-0.6 mg/kg) was administered in 30%, 57%, and 83%, respectively. The common areas of CFAE around the PVs were anterior to the right PVs, posterior to the left PVs, and at the ridge of the left atrial appendage. Among 215 PVs in 61 patients (42 paroxysmal, 19 persistent), only 17 PVs (8%) were unintentionally isolated. The atrial potential to PVP was prolonged (>30 ms) in 13% of PVs. After at least 12 months of follow-up (23 ± 5 months), 65% of paroxysmal (11% with drug), 54% of persistent (37% with drug), and 45% of long-standing (60% with drug) AF patients were free from atrial arrhythmia after one session. CONCLUSIONS CFAE-ablation terminates AF without isolating PVs in a high percentage of patients, and yields excellent clinical outcomes.

Atrial fibrillation-induced endothelial dysfunction improves after restoration of sinus rhythm

BACKGROUND Recent evidence suggests that atrial fibrillation (AF) adversely affects endothelial function. The goal of this study was to assess endothelial function in patients with AF before and after restoration of sinus rhythm by catheter ablation (ABL). METHODS Reactive hyperemia peripheral arterial tonometry (RH-PAT) measurements reflecting endothelial function were conducted with Endo-PAT2000 (Itamar Medical, Caesarea, Israel) in 27 patients with persistent AF before ABL and in 21 control subjects with sinus rhythm (SR). According to cardiac rhythm on the morning after ABL, patients were divided into two groups: day 1-restored SR group (n=19) and day 1-recurred AF group (n=8). Based on the cardiac rhythm at 6 months after ABL, the restored SR group was further subdivided into the month 6-maintained SR group (n=11) and the month 6-recurred AF group (n=6). RESULTS Loge RH-PAT index (RHI) was significantly lower in the persistent AF group than in the control (SR) group (0.52 ± 0.20; 0.69 ± 0.24, p<0.01). Multivariate logistic regression analysis revealed that persistent AF was the only independent predictor of impaired endothelial function defined as loge RHI<0.6 (odds ratio, 4.96; 95% CI, 1.2 to 21.3; p<0.05). Loge RHI was significantly higher after ABL than before ABL (0.53±0.20; 0.73 ± 0.25; p<0.01) in the day 1-restored SR group. Loge RHI of the month 6-maintained SR group was comparable to that of the day 1-restored SR group. CONCLUSIONS These results suggest that AF is associated with impairment of endothelial dysfunction and that this impairment is reversed by restoration of sinus rhythm.

The role of infection in the development of non-valvular atrial fibrillation: Up-regulation of Toll-like receptor 2 expression levels on monocytes

Many studies have suggested that inflammation may participate in the pathogenesis of non-valvular atrial fibrillation (AF). However, it has been unknown by exposure to what the inflammation is caused. Recently, we reported that Toll-like receptor 2 (TLR2) level on monocytes was significantly up-regulated in viral and bacterial infections, but not in non-infectious inflammatory states. Our purpose was to test the hypothesis that expression of TLR2 levels may be up-regulated in patients with non-valvular AF. A total of 48 consecutive patients with non-valvular AF who were hospitalized for catheter ablation were enrolled in this study. TLR2 levels were assayed by using flow-cytometric analysis and compared with volunteers in sinus rhythm (control group, n = 24). Additionally, C-reactive protein (CRP) and interleukin-6 (IL-6) levels were assayed, and the left atrial volume indexes (LAVI) in the non-valvular AF group were measured. The results demonstrated that TLR2 levels in the non-valvular AF group were significantly higher than in the control group (median, 4682 vs. 3866 sites/cell; P < 0.01). Moreover, non-valvular AF patients had significantly higher IL-6 levels than controls. However, there was no significant difference in CRP levels between the two groups. It was observed in 44 AF patients, in whom pulmonary vein isolation was confirmed to be successful, that the LAVI significantly diminished 1 month after ablation (median, 33.6 vs. 29.5 ml/m²; P < 0.001), but not the TLR2 and IL-6 levels. Our results implied that an infectious inflammation may participate in the pathogenesis of non-valvular AF.

Comparison of effect between nitrates and calcium channel antagonist on vascular function in patients with normal or mildly diseased coronary arteries

The comparative long-term antianginal efficacy of long-acting nitrates versus calcium channel antagonists remains unclear. The goal of the present study was to compare the coronary endothelial cell function and coronary artery vasoconstriction between patients with normal or mildly diseased coronary arteries treated with long-acting nitrates or calcium channel antagonists. Forty-two patients suspected to have angina pectoris and with normal or mildly diseased coronary arteries underwent Doppler flow study of the left anterior descending coronary artery. All patients were suspected to have angina pectoris and were receiving either long-acting nitrates (n = 18; Nitrates group) or calcium channel antagonists (n = 24; Ca-antagonists group) for at least 1 year. Vascular reactivity was assessed by intracoronary administration of papaverine, acetylcholine (Ach), and nitroglycerin using a Doppler guidewire. Segments that showed the greatest constrictive response to Ach were used for assessment of vasoconstriction. The percent increase in coronary blood flow (CBF) and coronary artery diameter (CAD) induced by Ach was significantly smaller in the Nitrates group than in the Ca-antagonists group (33% ± 74% vs 83% ± 77%, P < 0.05; −3% ± 16% vs 11% ± 12%, P < 0.01, respectively). The percent diameter reduction in the region of greatest constrictive response to Ach was significantly greater in the Nitrates group than in the Caantagonists group (44% ± 39% vs 15% ± 32%, P < 0.02). Long-term treatment with long-acting nitrates may produce less favorable effects on coronary endothelial function and the constrictive response to Ach when compared with long-acting calcium channel antagonists in patients with normal or mildly diseased coronary arteries.

Evaluation of safety and efficacy of periprocedural use of rivaroxaban and apixaban in catheter ablation for atrial fibrillation

BACKGROUND We previously reported that dabigatran increased the risk of microthromboembolism and hemopericardium compared with warfarin. The safety of non-vitamin-K-antagonist oral anticoagulants (NOACs) in the periprocedural use of atrial fibrillation (AF) ablation is controversial. This study aimed to compare the incidence of asymptomatic cerebral microthromboembolism and hemopericardium in AF ablation among periprocedural use of rivaroxaban, apixaban, and warfarin. METHODS AND RESULTS This study was a prospective, randomized registry. Patients taking NOACs upon visiting our hospital were randomly assigned into 2 groups; rivaroxaban and apixaban. Warfarin was continued in patients taking warfarin. Asymptomatic cerebral microthromboembolism was evaluated by magnetic resonance imaging on the day after the ablation procedure. In 176 consecutive patients (101 paroxysmal, and 75 persistent AF), rivaroxaban was used in 55, apixaban in 51, and warfarin in 70. There were no symptomatic cerebral infarctions in this study. Asymptomatic cerebral microthromboembolism was detected in 32 (18.4%) patients; nine (16.4%) with rivaroxaban, 10 (20%, p=0.80; vs. rivaroxaban) with apixaban, and 13 (18.8%, p=0.81; vs. rivaroxaban) with warfarin. Hemopericardium occurred in 5 (2.8%) patients; 2 with rivaroxaban, 1 with apixaban (p=1.0; vs. rivaroxaban), and 2 with warfarin (p=1.0; vs. rivaroxaban). In multivariate analysis, concomitant coronary angiography (p<0.05, odds ratio 5.73) was a predictor of cerebral thromboembolism. CONCLUSIONS The incidence of asymptomatic cerebral microthromboembolism and hemopericardium in AF ablation is similar among the periprocedural use of rivaroxaban, apixaban, and warfarin.

Association of coronary shear stress with endothelial function and vascular remodeling in patients with normal or mildly diseased coronary arteries

BackgroundThe relationship between coronary remodeling, shear stress and endothelial function remains unclear. ObjectiveThe present study investigated the effects of mechanical factors on structure and function of epicardial coronary arteries. MethodsPatients (group 1: %area stenosis<40%, n=55; or group 2: %area stenosis ≥40%, n=17) with a discrete mildly stenotic lesion (%diameter stenosis<30%) underwent intravascular ultrasound examination of the left anterior descending coronary artery for determination of vessel area, lumen area, plaque area, cross-sectional areas at reference segments, and remodeling index (the ratio of vessel area at the culprit lesion to vessel area at the proximal reference site). Further, vascular reactivity was examined using intracoronary administration of acetylcholine, papaverine, and nitroglycerin. ResultsVessel area significantly correlated with plaque area in both groups (r=0.65, P<0.0001 and r=0.85, P<0.0001). Group 1 showed significantly greater acetylcholine-induced percentage changes in coronary blood flow (67±70 vs. 16±75%, P<0.05) and coronary artery diameter (−7±18 vs.−32±31%, P<0.01) and also significantly smaller coronary wall shear stress (65±27 vs. 81±32 dynes/cm2, P<0.05) than group 2. The percentage increase in coronary blood flow induced by acetylcholine was significantly and positively correlated with remodeling index in group 1 (r=0.64, P<0.0001) but not in group 2 (r=−0.03, P=0.90) and was also significantly and positively correlated with coronary wall shear stress in group 1 (r=0.46, P<0.001) but not in group 2 (r=−0.33, P=0.19). ConclusionsEndothelium-dependent vasodilation in the resistance coronary artery correlates with remodeling via increased wall shear stress when target lesions %area stenosis is <40%.

Effectiveness of esophagus detection by three-dimensional electroanatomical mapping to avoid esophageal injury during ablation of atrial fibrillation

AIMS Esophageal-left atrial (LA) fistula during atrial fibrillation (AF) ablation is a fatal event. We explored the relation of the esophagus-to-ablated point distance and esophageal temperature rise. METHODS Consecutive patients (n=106) underwent complex fractionated atrial electrogram-guided AF ablation using CartoMerge; the pulmonary veins were isolated in 23 patients. Maximum radiofrequency (RF) power near the esophagus was 15 W. Ablated points with esophageal temperature rise (monitored with a probe) to ≥38.0°C were tagged; if ≥39.0°C, RF was discontinued. RESULTS Of 1647 ablated points near the esophagus, 274 were associated with a temperature rise to 38.0-38.9°C and 241 points to ≥39.0°C. Distances (mm) from points to esophagus were 5.1 ± 0.6 (no rise), 4.2±3.1 (38.0-38.9°C), 2.9 ± 2.5 (≥39.0°C). Altogether, 15.5% of points in the upper LA posterior wall, 41.5% in the middle, and 30.2% in the lower caused rises to ≥38.0°C; 8.7%, 24.6%, and 11.0% caused rises to ≥39.0°C. The middle wall was most affected (p<0.01), as shown by multiple logistic regression analysis (both temperatures). Points causing a rise increased significantly as distance decreased (p<0.001). The odds ratio for rise to ≥38.0°C compared with <4.0 to >5.0 mm distance was 2.28 (p=0.004). The longest distance for ≥38.0°C rise was 18.5 mm. CONCLUSION Distance is an important predictor of esophageal temperature rise. The middle LA posterior wall is most vulnerable. A dose of 15 W is too high for ablation, especially <4.0 mm from the esophagus. Points >20.0 mm away are relatively safe.

Catheter ablation of atrial fibrillation guided by complex fractionated atrial electrogram mapping with or without pulmonary vein isolation

Pulmonary vein isolation (PVI) was the main strategy for catheter ablation of atrial fibrillation (AF) until a remarkable report was published by Nademanee et al. in 2004. The ablation targeting complex fractionated atrial electrograms (CFAE) achieved not only a high rate of AF termination but also excellent outcomes in both paroxysmal and persistent AF without isolating pulmonary veins. AF is thought to be caused by random or spiral reentry, as the fixed circuit to maintain AF may not exist, although the CFAE‐guided ablation strategy is based on the theory that AF is not entirely random. CFAEs play an important role in identifying AF substrates, and have temporal and spatial stability, thus representing desirable targets for AF ablation; however, CFAE‐guided ablation has not been fully replicated by others. In reports showing that CFAE ablation did not yield a good outcome either alone or combined with PVI, the AF termination rates were extremely low. Although AF termination is not mandatory in CFAE‐ablation, terminating AF in the majority of patients appears to be necessary to yield good outcomes; therefore, this review will discuss AF ablation guided by CFAE with or without PVI, with particular emphasis given to practical aspects of achieving AF termination.