Sympathetic nerve abnormality in an adolescent patient with cardioinhibitory vasovagal syncope.

A 15 year-old-Japanese girl was admitted to our ward because of syncope. Electrocardiography (ECG) demonstrated sinus bradycardia with heart rate of 52/min. Holter ECG showed no arrhythmia related to syncope. Coronary enhanced computed tomography and cardiac magnetic resonance imaging showed no abnormal findings. Head-up tilt test revealed syncope with sinus arrest. 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy revealed focally decreased uptake on the anterior wall of the left ventricle but generally maintained uptake of MIBG. Finally, she was diagnosed with cardioinhibitory vasovagal syncope (CIVS). Sympathetic nerve abnormalities seemed to be related to CIVS in this patient. .

Successful management of heart failure 45 years after surgical correction of tetralogy of Fallot.

A 59-year-old Japanese woman was admitted with heart failure due to severe pulmonary regurgitation and tricuspid regurgitation, in addition to atrial fibrillation 45 years after surgical correction of tetralogy of Fallot (TOF). She had been under treatment with medication and catheter ablation for arrhythmia including ventricular tachycardia for the past 28 years. She underwent pulmonary valve replacement as well as tricuspid and mitral valvuloplasty, which obviously improved her status even though her right ventricular end-diastolic volume index exceeded the recommended threshold. Patients who have undergone surgical correction of TOF need to be managed over the long term. .

Correlation between Transient Hypotension and Exclusively Exercise-induced Symptoms of Two-to-One Atrioventricular Block.

A 62-year-old woman with activity-dependent two-to-one atrioventricular block (2:1AVB) and a normal left ventricular ejection fraction was referred to our department for the evaluation of exclusively exercise-induced marked symptoms. The treadmill test helped establish a clear correlation between 2:1AVB and symptoms. The test results demonstrated that exercise-induced marked symptoms were attributed to abrupt transient hypotension combined with relative bradycardia, probably due to increased diastolic mitral and tricuspid regurgitation because of 2:1AVB during moderate-to-heavy exercise. After pacemaker implantation for 2:1AVB, the symptoms and transient hypotension disappeared, and her exercise capacity improved.

Randomized, Open-Label, Cross-Over Comparison of the Effects of Benzbromarone and Febuxostat on Endothelial Function in Patients with Hyperuricemia.

Uric acid is generated with reactive oxygen species via xanthine oxidase (XO), and hyperuricemia, which is identified as the excess of uric acid in the blood, has been associated with vascular endothelial dysfunction. However, the effects of urate-lowering medicines on endothelial function have not been fully elucidated. Thus this study determined and compared the effects of benzbromarone (urate transporter 1 inhibitor) and febuxostat (XO inhibitor) on endothelial function.This randomized, cross-over, open-label study initially recruited 30 patients with hyperuricemia. They were divided into two groups, treated initially with benzbromarone or febuxostat for three months and then were switched for the next three months. Endothelial function was defined as reactive hyperemia indexes (RHI) determined using Endo-PAT 2000 before and at three and six months after medication using the two agents. Blood levels of asymmetric dimethylarginine (ADMA) and high-molecular-weight (HMW) adiponectin were also compared. We finally analyzed data from 24 patients whose endothelial function was assessed as described above.Our findings show that levels of uric acid significantly decreased, whereas those of HMW adiponectin and the RHI have significantly increased after treatment with benzbromarone. Meanwhile, in patients administered with febuxostat, uric acid levels tended to decrease and RHI significantly decreased. Neither of the two agents altered ADMA levels. The changes in RHI (P = 0.026) and HMW adiponectin levels (P = 0.001) were found to be significantly greater in patients treated with benzbromarone than febuxostat. Changes in the levels of HMW adiponectin and of uric acid were significantly correlated (r = -0.424, P = 0.039).Benzbromarone has increased adiponectin besides reducing uric acid levels, and thus, this might confer more benefits on endothelial function than febuxostat.

Pulmonary Artery Aneurysm Associated with Bicuspid Pulmonary Valve.

A 73-year-old Japanese man was admitted with an asymptomatic pulmonary artery aneurysm. However, chest X-ray and contrast-enhanced thoracic computed tomography revealed a protrusion at the second left branch that in fact was a pulmonary artery aneurysm with a diameter of 50 mm. Transesophageal echocardiography showed a bicuspid pulmonary valve, and cardiac catheterization revealed pulmonary stenosis with a pressure gradient of 45 mmHg, but no other heart diseases were noted. An extremely rare pulmonary artery aneurysm associated with an isolated bicuspid pulmonary valve was diagnosed.

Postural Orthostatic Tachycardia in a Patient with Type 2 Diabetes with Diabetic Neuropathy.

A 24-year-old Japanese man with type 2 diabetes mellitus and diabetic neuropathy was admitted to our ward to evaluate the cause of orthostatic intolerance. During a head-up tilt test, his heart rate increased from 105 to 155 beats/minute within 3 minutes, and chest discomfort began. He was diagnosed with postural orthostatic tachycardia syndrome (POTS), and orthostatic intolerance disappeared after ß-blocker treatment. Scintigraphy using 123I-metaiodobenzylguanidine showed decreased cardiac uptake. Power spectral analysis of heart rate variability for 24 hours in Holter electrocardiography demonstrated decreases in both sympathetic and parasympathetic nervous system activities, with a greater decrease in parasympathetic activity than sympathetic activity. The relative sympathetic hyperactivity in the present patient with diabetic neuropathy seemed to be related to POTS.

Compact and high-sensitivity 100-Gb/s (4 × 25 Gb/s) APD-ROSA with a LAN-WDM PLC demultiplexer.

We demonstrate an integrated 100 GbE receiver optical sub-assembly (ROSA) that incorporates a monolithic four-channel avalanche photodiode (APD) array and a planer lightwave circuit (PLC) based LAN-WDM demultiplexer. A record minimum receiver sensitivity of -20 dBm and 50-km error-free SMF transmission without an optical amplifier have been achieved.

Ventricular fibrillation in a patient with prominent j wave in the inferior and lateral electrocardiographic leads after gastrostomy.

We describe the case of a 39-year-old man who experienced a ventricular fibrillation storm related to a prominent J wave in the inferior and lateral electrocardiographic leads on the day after gastrostomy. The J wave slowly decreased after amiodarone therapy (400 mg/day) was started, and ventricular fibrillation disappeared.

Efectos del envejecimiento sobre los períodos refractarios y la conducción auricular en pacientes con fibrilación auricular paroxística idiopática obtenidos mediante estimulación auricular programada / The effects of aging on the refractoriness and conduction of the atrium in patients with lone paroxysmal atrial fibrllation revealed with programmed atrial stimulation

El propósito de este estudio es determinar si el envejecimiento influye sobre la vulnerabilidad auricular inducida por la estimulación auricular programada en pacientes con fibrilación auricular paroxística idiopática. La investigación incluyó a 148 pacientes, de los cuales 78 tenían fibrilación auricular paroxística idiopática y 70 eran pacientes control. Para determinar los efectos de la edad sobre la vulnerabilidad auricular, dividimos a los pacientes con fibrilación auricular en dos grupos: el grupo mayor tuvo 38 pacientes ®g60 años de edad y el grupo más joven tuvo 40 pacientes <60 años de edad. Los siguientes parámetros de vulnerabilidad auricular fueron estudiados y medidos cuantitativamente: 1) el período refractario efectivo auricular, 2) la zona del retardo de la conducción auricular, y 3) el máximo retardo en la conducción auricular. El período refractario efectivo auricular promedio del grupo más joven (201±28 msec) fue significativamente más corto que el del grupo mayor de edad (215±27 msec, p<0.05) y que el del grupo control (215± 29 msec. p<0.02). La zona del retardo en la conducción auricular promedio del grupo mayor (50±25 msec) y la del grupo más joven (50±31 msec) fueron significativamente más amplias que la del grupo control (34±22 msec) (p<0.01). El máximo retardo en la conducción auricular del grupo mayor (65±31 msec) y el del grupo más joven (58±27 msec) fueron significativamente más amplios que el del grupo control (43±20 msec) (p<0.01). Por lo tanto, si bien el retardo en la conducción auricular se observa tanto en los pacientes más jóvenes como en los mayores de edad, el período refractario efectivo auricular es más corto en los pacientes más jóvenes con fibrilación auricular paroxística idiopática. Estos resultados sugieren diferencias dependientes de la edad en la fisiopatología de la fibrilación auricular

Relation between history of paroxysmal atrial fibrillation and electrophysiological abnormalities of atrial muscle.

Although electrophysiological abnormalities of atrial muscle have been evaluated in patients with paroxysmal atrial fibrillation (PAF), no prior study has determined the contribution of the patient's history of PAF to electrophysiological abnormalities. The study population consisted of 108 patients (71 men; mean age, 57 +/- 14 years) with symptomatic and idiopathic PAF who underwent electrophysiological study. Before electrophysiological study, histories of frequency, number of PAF episodes per month, and duration, a time interval from the first episode of PAF to electrophysiological study, were examined. At electrophysiological study, endocardial electrograms from 12 right atrial sites were recorded during sinus rhythm, and the right atrial effective refractory period was determined. Longest duration of atrial electrograms, maximal number of fragmented deflections, and number of abnormal atrial electrograms recorded at the right atrial sites were significantly greater in the frequent group (> 1 PAF episode per month, n = 57) than in the infrequent group (< 1 PAF episode per month, n = 51) (98 +/- 18 ms vs 88 +/- 16 ms, P < 0.005; 8.7 +/- 2.6 vs 7.5 +/- 2.6, P < 0.05; and 2.2 +/- 2.2 vs 1.4 +/- 1.6, P < 0.05, respectively). Indices of atrial vulnerability were also greater in the frequent group. Duration of PAF history was significantly correlated with longest duration r = 0.52, P < 0.0001), maximal number of fragmented deflections r = 0.51, P < 0.0001), and number of abnormal atrial electrograms r = 0.58, P < 0.0001). More frequent episodes and longer history of PAF significantly increased the electrophysiological abnormalities of the atrial muscle, suggesting that PAF results in gradual electrical remodeling of the atrial muscle.

Abnormal right atrial electrograms predict the transition to chronic atrial fibrillation in paced patients with sick sinus syndrome.

Although pacing therapy for sick sinus syndrome (SSS) is established, the risk of developing chronic atrial fibrillation (CAF) makes pacing therapy infeasible in some patients. We evaluated whether electrophysiological characteristics of atrial muscle can serve as predictors of the transition to CAF after pacemaker implantation in patients with SSS. Eighty-nine patients with SSS underwent electrophysiological study before pacing therapy. Catheter mapping of 12 right atrial sites was performed during sinus rhythm during electrophysiological. An abnormal atrial electrogram was defined as having a duration of 100 ms or longer, or eight or more fragmented deflections, or both. Right atrial extrastimulation was also performed for atrial vulnerability. After electrophysiological study, all patients underwent pacemaker implantation and were followed up. During the follow-up period of 85 +/- 50 months, development of CAF was observed in 12 patients (group A). The remaining 77 patients remained in sinus rhythm (group B). There were significantly more abnormal atrial electrograms in group A than group B (2.7 +/- 2.3 vs 0.8 +/- 1.2; P < 0.001). The distribution of abnormal atrial electrograms was also greater in group A; patients in group A had more abnormal atrial electrograms than patients in group B in both the high and middle right atrium (P < 0.005 and P < 0.01, respectively). Kaplan-Meier analysis showed that almost 50% of the paced patients with abnormal atrial electrograms (n = 42) developed CAF (P < 0.005). Our data suggest that the existence of abnormal atrial electrograms is predictive of the transition to CAF in paced patients with SSS.

A patient with LQTS in whom verapamil administration and permanent pacemaker implantation were useful for preventing torsade de pointes.

A 21-year-old woman with long QT syndrome and missense mutation in HERG (T613M), suffered from repeated attacks of pause dependent torsade de pointes, even though she was given beta-blockers and underwent stellate ganglion block twice at the age of eight. After she received permanent pacemaker implantation and administration of verapamil, no premature beats or pause dependent torsade de pointes was observed.

Site of action of the general anesthetic propofol in muscarinic M1 receptor-mediated signal transduction.

Although a potential target site of general anesthetics is primarily the GABA A receptor, a chloride ion channel, a previous study suggested that the intravenous general anesthetic propofol attenuates the M1 muscarinic acetylcholine receptor (M1 receptor)-mediated signal transduction. In the present study, we examined the target site of propofol in M1 receptor-mediated signal transduction. Two-electrode voltage-clamp method was used in Xenopus oocytes expressing both M1 receptors and associated G protein alpha subunits (Gqalpha). Propofol inhibited M1 receptor-mediated signal transduction in a dose-dependent manner (IC50 = 50 nM). Injection of guanosine 5'-3-O-(thio)triphosphate (GTPgammaS) into oocytes overexpressing Gqalpha was used to investigate direct effects of propofol on G protein coupled with the M1 receptor. Propofol did not affect activation of Gqalpha-mediated signal transduction with the intracellular injection of GTPgammaS. We also studied effects of propofol on l-[N-methyl-3H]scopolamine methyl chloride ([3H]NMS) binding and M1 receptor-mediated signal transduction in mammalian cells expressing M1 receptor. Propofol inhibited the M1 receptor-mediated signal transduction but did not inhibit binding of [3H]NMS. Effects of propofol on Gs- and Gi/o-coupled signal transduction were investigated, using oocytes expressing the beta2 adrenoceptor (beta2 receptor)/cystic fibrosis transmembrane conductance regulator or oocytes expressing the M2 muscarinic acetylcholine receptor (M2 receptor)/Kir3.1 (a member of G protein-gated inwardly rectifying K(+) channels). Neither beta2 receptor-mediated nor M2 receptor-mediated signal transduction was inhibited by a relatively high concentration of propofol (50 microM). These results indicate that propofol inhibits M1 receptor-mediated signal transduction by selectively disrupting interaction between the receptor and associated G protein.

Identification of human Kir2.2 (KCNJ12) gene encoding functional inward rectifier potassium channel in both mammalian cells and Xenopus oocytes.

Arginine residue at position 285 (R285) in the intracellular C-terminal domain of inward rectifier potassium channel Kir2.2 is conserved in many species, but missing in previously reported human Kir2.2 sequences. We here identified the human Kir2.2 gene in normal individuals, which contained R285 in the deduced amino-acid sequence (hKir2.2/R285). All 30 individuals we examined were homozygous for Kir2.2/R285 gene. The hKir2.2/R285 was electrophysiologically functional in both mammalian cells and Xenopus oocytes. However, the hKir2.2 missing R285 was functional only in Xenopus oocytes, but not in mammalian cells. Thus, R285 in Kir2.2 is important for its functional expression in mammalian cells.