High-Tc nodeless s±-wave superconductivity in (Y,La)FeAsO(1-y) with Tc=50 K:75As-NMR study.

We report on an (75)As-NMR study on the Fe-pnictide high-T(c) superconductor Y(0.95)La(0.05)FeAsO(1-y) (Y(0.95)La(0.05)1111) with T(c)=50 K that includes no magnetic rare-earth elements. The measurement of the nuclear-spin lattice-relaxation rate (75)(1/T(1)) has revealed that the nodeless bulk superconductivity takes place at T(c)=50 K while antiferromagnetic spin fluctuations develop moderately in the normal state. These features are consistently described by the multiple fully gapped s(±)-wave model based on the Fermi-surface nesting. Incorporating the theory based on band calculations, we propose that the reason that T(c)=50 K in Y(0.95)La(0.05)1111 is larger than T(c)=28 K in La1111 is that the Fermi-surface multiplicity is maximized, and hence the Fermi-surface nesting condition is better than that in La1111.

Possibility of valence-fluctuatsion-mediated superconductivity in Cd-doped CeIrIn(5) probed by In NQR.

We report on a pressure-induced evolution of exotic superconductivity and spin correlations in CeIr(In(1-x)Cd(x))(5) by means of in-nuclear-quadrupole-resonance (NQR) studies. Measurements of an NQR spectrum and nuclear-spin-lattice-relaxation rate 1/T(1) have revealed that antiferromagnetism induced by Cd doping emerges locally around Cd dopants, but superconductivity is suddenly induced at T(c)=0.7 and 0.9 K at 2.34 and 2.75 GPa, respectively. The unique superconducting characteristics with a large fraction of the residual density of state at the Fermi level which increases with T(c) differ from those for anisotropic superconductivity mediated by antiferromagnetic correlations. By incorporating the pressure dependence of the NQR frequency pointing to the valence change of Ce, we suggest that unconventional superconductivity in the CeIr(In(1-x)Cd(x))(5) system may be mediated by valence fluctuations.

Antiferromagnetic spin fluctuations and unconventional nodeless superconductivity in an iron-based new superconductor (Ca4Al2O(6-y))(Fe2As2): 75As nuclear quadrupole resonance study.

We report 75As nuclear quadrupole resonance studies on (Ca4Al2O(6-y))(Fe2As2) with T(c) = 27 K. Measurement of nuclear-spin-relaxation rate 1/T1 has revealed a significant development of two-dimensional antiferromagnetic spin fluctuations down to T(c) in association with the smallest As-Fe-As bond angle. Below T(c), the temperature dependence of 1/T1 without any trace of the coherence peak is well accounted for by a nodeless s(±)-wave multiple-gaps model. From the fact that its T(c) is comparable to T(c) = 28 K in the optimally doped LaFeAsO(1-y) in which antiferromagnetic spin fluctuations are not dominant, we remark that antiferromagnetic spin fluctuations are not a unique factor for enhancing T(c) among Fe-based superconductors, but a condition for optimizing superconductivity should be addressed from the lattice structure point of view.

Life cycle of Cyclestheria hislopi (Baird, 1859) (Crustacea, Branchiopoda).

The Conchostraca (clam shrimps) are a group of microcrustaceans found in freshwater habitats. They inhabit the benthos, yet many can swim actively and are often associated with macrophytes. They are filter-feeders, deriving their food from suspended particles or solids stirred up from the bottom. In Brazil, five species have been recorded and the life cycle of one of these, Cyclestheria hislopi (Baird, 1859) was investigated in this study. Specimens were collected from fish-farming tanks in upstate São Paulo and from the floodplain of the Miranda River, in the Mato Grosso swamplands of center-west, Brazil. We determined the following variables: post-embryonic development, duration of life cycle (longevity), mean period between broods, duration of instars and individual growth. Taxonomic features of the Cyclestheria sp. specimens from Mato Grosso were also assessed to check the possibility that they belonged to another species of the same genus or a separate ecotype of C. hislopi.

Structure and electrical properties of the new pyrochlore-type protonic solid electrolyte K(0.88)Nb2O(7.58)H(4.28).

Single-crystal, synchrotron powder X-ray diffraction and neutron powder diffraction studies of the novel pyrochlore-type compound with the structural formula K(0.88)(OH)(0.54)H(1.66)(H(2)O)(1.04)Nb(2)O(6) suggests that the water molecules are located in 32e sites, and the hydroxide ions and potassium ions are located in 16d sites with a significant amount of 'free' protons in 96g sites. The total weight loss at temperatures up to 773 K is only about 8%, suggesting the oxygen escape from 48f sites can be excluded and 'free' protons must be preserved in the structure. The bulk conductivity in ambient air reaches 10(-2) S cm(-1) at 623 K. Owing to the extended stability range and resistance to water solubility, the compound can be considered as a candidate for intermediate temperature solid-oxide fuel-cell applications.

Spin susceptibility of noncentrosymmetric heavy-fermion superconductor CeIrSi3 under pressure: 29Si Knight-shift study on single crystal.

We report 29Si NMR study on a single crystal of the heavy-fermion superconductor CeIrSi3 without an inversion symmetry along the c axis. The 29Si Knight-shift measurements under pressure have revealed that the spin susceptibility for the ab plane decreases slightly below T(c), whereas along the c axis it does not change at all. The result can be accounted for by the spin susceptibility in the superconducting state being dominated by the strong antisymmetric (Rashba-type) spin-orbit interaction that originates from the absence of an inversion center along the c axis and it being much larger than superconducting condensation energy. This is the first observation which exhibits an anisotropy of the spin susceptibility below T(c) in the noncentrosymmetric superconductor dominated by strong Rashba-type spin-orbit interaction.

[Myers technique and patch enlargement of ascending aorta for diffuse supravalvular aortic stenosis].

A 6-year-old boy was diagnosed with aggravation of diffuse supravalvular aortic stenosis (SVAS). The pressure gradient between the sinus of Valsalva and ascending aorta was 48 mmHg. The diameter of the sino-tubular junction was 7 mm and the ascending aorta was hypoplastic. We performed Myers operation because 3 sinus reconstructions had resulted in superior hemodynamics and reductions in both mortality rate and need for reoperation. We avoided using autologous pericardium because of the possibility of shrinkage and aneurysm. We could easily perform patch enlargement of the ascending aorta by selective cerebral perfusion. The postoperative course was excellent and there was no SVAS or aortic regurgitation (AR). A catheterization showed the pressure gradient was 5 mmHg with trivial AR upon follow-up at 1 year.

Enhancement of superconducting transition temperature due to the strong antiferromagnetic spin fluctuations in the noncentrosymmetric heavy-fermion superconductor CeIrSi3: A 29Si NMR study under pressure.

We report a (29)Si NMR study on the pressure-induced superconductivity (SC) in an antiferromagnetic (AFM) heavy-fermion compound CeIrSi(3) without inversion symmetry. In the SC state at P = 2.7-2.8 GPa, the temperature (T) dependence of the nuclear-spin lattice relaxation rate 1/T(1) below T(c) exhibits a T(3) behavior without any coherence peak just below T(c), revealing the presence of line nodes in the SC gap. In the normal state, 1/T(1) follows a square root T-like behavior, suggesting that the SC emerges under the non-Fermi-liquid state dominated by AFM spin fluctuations enhanced around a quantum critical point. The reason why the maximum T(c) in CeIrSi(3) is relatively high among the Ce-based heavy-fermion superconductors may be the existence of the strong AFM spin fluctuations. We discuss the comparison with the other Ce-based heavy-fermion superconductors.

[Primary biventricular repair for interrupted aortic arch with left ventricular outflow tract obstruction and tricuspid valve regurgitation; report of a case].

An interrupted aortic arch was diagnosed in a 10-day-old girl weighing 3.3 kg, as was perimembranous ventricular septal defect (VSD) and severe tricuspid valve regurgitation (TR). The subaortic diameter was 3.6 mm and the aortic valve (3.7 mm in diameter) was bicuspid. We chose definitive repair, modified Yasui procedure, because of severe TR and no straddling of mitral valve. In primary biventricular repair, we undertook extended aortic arch anastomosis. Left ventricular outflow tract reconstruction consisted of intracardiac rerouting from the VSD to the pulmonary artery by using expanded-polytetrafluoroethylene (ePTFE) and Damus-Kaye-Stansel (DKS) anastomosis. Right ventricular outflow tract reconstruction was performed by the Rastelli procedure with an ePTFE valved conduit. Moreover, we carried out semicircular annuloplasty for severe TR.

[Fontan operation for tricuspid atresia with dysplasia of the right ventricular myocardium and absence of pulmonary valve].

We report a case of successful staged repair of tricuspid atresia with dysplasia of the right ventricular myocardium and absence of the pulmonary valve. The patient underwent the modified Blalock-Taussig shunt operation at 1 month the bidirectional Glenn procedure at 11 months, and the total cavopulmonary connection procedure using extracardiac graft at 2 years. It is important to prevent the left ventricular outflow tract obstruction (LVOTO) caused by the non-functioning right ventricle when the Fontan completion. We were safely able to disconnect the pulmonary trunk from the right ventricle using the transesophageal echocardiography to evaluate the LVOTO during operation.

[Sandwich technique for closing of the large muscular Swiss-cheese type ventricular septal defects].

A 9-year-old girl, who has had a diagnosis as a Taussig-Bing anomary, underwent an original Jatene procedure (o-J) 2 months after birth. This time, she had a diagnosis of the muscular multiple ventricular septal defects (mVSD) and pulmonary stenosis after o-J. The mVSD was Swiss-cheese type and was large from the proximal of the infundibular septum to the apex and posterior of the septum. It was closed by the sandwich technique using a pair of felt patches, which of one was placed at right ventricular side and the other was at left ventricular side, slightly larger than the whole area of the mVSD. The patch fixation was placed with 1 stitch at the center between the patches and a few stitches around the right ventricular side patch to the ventricular septum. Postoperative cardiac function was uneventful regardless of the very large patches placed at the ventricular septum and the cardiac catheterization after 1 year postoperatively showed the pulmonary/systemic blood flow ratio was 1.0. This technique for the closure of the large Swiss-cheese type mVSD can be considered to be very effective.

[Successful staged repair of a symptomatic neonate of tetralogy of Fallot with severe absent pulmonary valve syndrome].

Tetralogy of Fallot with absent pulmonary valve has been classified to a few groups. The most severe one is characterized by symptomatic onset immediately after birth. The others are no or slightly symptomatic at least during their neonatal period. In a severely symptomatic 12-day-old neonate of tetralogy of Fallot with absent pulmonary valve who had required intubation immediately after birth, tight pulmonary banding and left side modified Blalock-Taussig shunt were performed on emergency basis. Consequently, prior massive pulmonary regurgitation was decreased significantly. Forty-five days after this first stage operation, he weaned from respiratory management. At 1-year-old, radical repair based on conotruncal repair, which consisted of patch closure of ventricular septal defect preserving the tricuspid septal leaflet function, resection of anterior wall of enlarged left pulmonary artery, and right ventricular outflow tract reconstruction using autologous tissue and a pericardial patch was performed. Bicuspid pulmonary valve, posterior one of procured autologous pulmonary wall and anterior one of polytetrafluoroethylene (PTFE) respectively, was created to minimize deterioration of the pulmonary insufficiency. Although postoperative cardiac function was kept feasible showing his central venous pressure of 7 mmHg in the main, postoperative general course was eventful especially regarding the respiratory function. The patient was weaned from the prolonged ventilator management 5 months after this radical repair eventually. Generally, to diminish the massive pulmonary regurgitation in early lifetime period could reduce a progressive airway obstruction and minimize pulmonary tissue damage. However, even after the total correction in this case, considerable peripheral segmental pulmonary obstructive lesions were persistent according to the perfusion lung scanning with 99mTc macroaggregated albumin and 99mTechnegas ventilation lung scanning studies. This persistent, supposed to be innate, pulmonary obstructive lesions might prevent ordinal recovery after cardiac radical repair for this most severe subtype of absent pulmonary valve syndrome.

[Valvuloplasty for mitral regurgitation immediately following Kawasaki disease without abnormal coronary arteries lesion; report of a case].

It is not uncommon that valve disease is complicated with Kawasaki disease (KD). However, it is rare to show normal coronary arteries simultaneously. We experienced a case of valvuloplasty towards the mitral regurgitation (MR) followed immediately after KD showing normal coronary arteries. A 3 year-old-female, with a diagnosis of KD at 4 months after birth, was referred to our hospital 5 months after birth. The echocardiography detected a moderate MR. The preoperative catheterization at 2.5 years old showed grade III MR, enlargement of left atrium and left ventricle, pulmonary capillary wedge pressure (PCWP) = 12 mmHg, left ventricular ejection fraction (LVEF) = 675, and normal coronary arteries. Pulmonary hypertention was not revealed. The operative findings showed mitral valve prolapse due to the elongation of the chordae of the anterior leaflet. She underwent artificial chordal reconstruction using expanded polytetrafluoroethylene sutures and mitral annuloplasty by Kay-Reed method. The postoperative course was uneventful, and she was discharged on postoperative day 19.

Progressive action potential duration shortening and the conversion from atrial flutter to atrial fibrillation in the isolated canine right atrium.

OBJECTIVES: We sought to evaluate the effects of progressive shortening of the action potential duration (APD) on atrial wave front stability. BACKGROUND: The mechanisms of conversion from atrial flutter to atrial fibrillation (AF) are unclear. METHODS: Isolated canine right atria were perfused with 1 to 5 micromol/l of acetylcholine (ACh). We mapped the endocardium by using 477 bipolar electrodes and simultaneously recorded transmembrane potentials from the epicardium. The APD(90) was measured during regular pacing (S(1)) with cycle lengths of 300 ms. Atrial arrhythmia was induced by a premature stimulus (S(2)). RESULTS: At baseline, only short runs of repetitive beats (<10 cycles) were induced. After shortening the APD(90) from 124 +/- 15 ms to 72 +/- 9 ms (p < 0.01) with 1 to 2.5 micromol/l of ACh, S(2) pacing induced single, stable and stationary re-entrant wave fronts (307 +/- 277 cycles). They either anchored to pectinate muscles (5 tissues) or used pectinate muscles as part of the re-entry (4 tissues). When ACh was raised to 2.5 to 5 micromol/l, the APD(90) was further shortened to 40 +/- 12 ms (p < 0.01); S(2) pacing induced in vitro AF by two different mechanisms. In most episodes (n = 13), AF was characterized by rapid, nonstationary re-entry and multiple wave breaks. In three episodes with APD(90) <30 ms, AF was characterized by rapid, multiple, asynchronous, but stationary wave fronts. CONCLUSIONS: Progressive APD shortening modulates atrial wave front stability and converts atrial flutter to AF by two mechanisms: 1) detachment of stationary re-entry from the pectinate muscle and the generation of multiple wave breaks; and 2) formation of multiple, isolated, stationary wave fronts with different activation cycle lengths.

Common iliac artery aneurysm due to fibromuscular dysplasia in infants.

A seven-month old female with a huge aneurysm of the right common iliac artery and multiple stenoses of her bilateral renal arteries is described. At surgery, a Gore-Tex graft was interposed between the proximal common iliac artery and the external iliac artery. A histological examination of the aneurysmal wall was compatible with medial fibromuscular dysplasia (FMD). After surgery, her blood pressure was controlled in the normal range on medical treatment. This case would be the first case of a huge common iliac artery aneurysm due to FMD in infants.

Pulmonary veins and ligament of Marshall as sources of rapid activations in a canine model of sustained atrial fibrillation.

BACKGROUND: In dogs, chronic rapid pacing may result in sustained atrial fibrillation (AF). However, activation patterns in pacing-induced sustained AF are unclear. METHODS AND RESULTS: We induced sustained AF (>48 hours) in 6 dogs by rapid pacing for 139+/-84 days. We then performed computerized atrial epicardial mappings and recorded the activations in the ligament of Marshall (LOM) and the pulmonary veins (PVs). During AF, mean activation cycle length in the right atrial free wall (126+/-17 ms) was significantly longer than that in the left atrial free wall (96+/-5 ms, P:=0.006). In addition, mean activation cycle length in the left atrial free wall was significantly longer than that in the LOM (84+/-5 ms, P:<0.001), the left inferior PV (81+/-4 ms, P:=0.001), and the left superior PV (85+/-7 ms, P:=0.003). Similarly, the dominant frequency was highest in the LOM and the PVs (range 11.2 to 13.3 Hz), followed by the left and right atria (P:<0.001). In all dogs studied, rapid and complicated electrograms were consistently observed at the LOM and the PVs. During AF, both wandering wavelets and organized reentry were present. There were more wave fronts in the left atrium than in the right atrium (P:<0.001). CONCLUSIONS: In chronic pacing-induced sustained AF, the LOM and the PVs are the sources of rapid activations. The mechanism by which the left atrium activates faster and has more wave fronts than the right atrium may relate to the fact that the left atrium is closer to the sources of rapid activations.

Obstacle-induced transition from ventricular fibrillation to tachycardia in isolated swine right ventricles: insights into the transition dynamics and implications for the critical mass.

OBJECTIVES: The study was done to test the hypothesis that an artificial anatomical obstacle prevents the maintenance of ventricular fibrillation (VF) by stabilizing reentrant wavefronts (RWF) and increases the critical mass (CM) of myocardium required to sustain VF. BACKGROUND: Artificial obstacles can anchor RWF in simulated models of VF. Whether an artificial obstacle affects multiple-wavelet VF in real tissue is unclear. METHODS: The endocardial surfaces of seven isolated, perfused swine right ventricles were mapped using a plaque of 477 bipolar electrodes with 1.6-mm resolution. An 8-mm hole was punched in the tissue. The CM was reached by tissue mass reductions, at which VF converted to periodic activity (ventricular tachycardia, VT). RESULTS: After the creation of the obstacle, the VF cycle length increased from 71.6+/-18.4 ms to 87.5+/-13.0 ms (p<0.05). The obstacle, together with the papillary muscle, facilitated the transition from VF to VT by serving as attachment sites for the RWF. When one RWF attaches to the obstacle and another attaches to the papillary muscle, it may result in stable VT with figure-eight patterns. The CM for VF in the presence of an 8-mm hole (28.7+/-3.8 g) was higher than in the control group (swine right ventricles without holes, 24.0+/-3.4 g, p<0.05). CONCLUSIONS: An artificial anatomical obstacle induces slowing and regularization of VF, impairs the persistence of VF as judged by an increase of the CM, and can convert VF to VT by serving as an attachment site to reentrant excitation.

Influence of wavefront dynamics on transmembrane potential characteristics during atrial fibrillation.

INTRODUCTION: Although computerized mapping studies have demonstrated the presence of multiple wavelets during atrial fibrillation (AF) and that action potential amplitude and duration in AF vary significantly from beat to beat, no study has correlated the single cell action potential changes with the patterns of activation during AF. METHODS AND RESULTS: We studied wavefront dynamics and single cell transmembrane potential (TMP) characteristics in 12 isolated perfused canine right atria. The endocardial surface was mapped using 477 bipolar electrodes while TMP was recorded with a standard glass microelectrode from an epicardial cell. AF was induced in the presence of acetylcholine. Successful simultaneous TMP recordings and activation maps were made during six episodes of AF and for a total of 141 activations. Large variations of TMP amplitude and duration were observed frequently; 34% of them have a low amplitude (<50% of the amplitude recorded during pacing). Low-amplitude potentials were recorded when the impaled cell was (1) in an area of random reentry (67%, n = 36); (2) within 3.2 mm of the core of organized functional reentry (22%, n = 12); (3) in the middle of two merging wavefronts (9%, n = 5); and (4) at the point of spontaneous wavebreak (2%, n = 1). CONCLUSION: Large variations of TMP are observed frequently during in vitro AF. Low-amplitude TMPs are associated with specific patterns of AF activation wavefronts.

Pharmacokinetics of landiolol hydrochloride, a new ultra-short-acting beta-blocker, in patients with cardiac arrhythmias.

OBJECTIVES: To elucidate pharmacokinetics and pharmacodynamics of landiolol hydrochloride, newer developed ultra-short-acting beta-blocker, in patients with various cardiac tachyarrhythmias. BACKGROUND: The short duration of action and titratability of landiolol hydrochloride make it ideal for use in patients with a clinical need for beta-blockers. METHODS: In a total of 31 examinations we infused the drug in 19 patients (mean age, 55 +/- 14 years). After the persistence of the tachyarrhythmias was confirmed, continuous infusion was started at rates of 0.005, 0.01, 0.02, 0.04, and 0.08 mg/kg/min for 5 minutes (for paroxysmal atrial fibrillation, paroxysmal supraventricular tachycardia, and ventricular tachycardia) or 15 minutes (for ventricular premature complex). We analyzed the pharmacokinetics of 16 examinations. A one-compartment model provided a close fit for each blood concentration-time curve. RESULTS: The maximum blood concentrations obtained clearly showed the dose dependency and revealed very short half-lives (range, 2.3 to 4.0 minutes). Area under the blood concentration-time curves also increased, showing dose dependency. In paroxysmal atrial fibrillation, landiolol hydrochloride reduced the heart rate from 111 +/- 20 to 90 +/- 10/min. Sinus rhythm was restored, without any adverse effects, in three of five patients with paroxysmal supraventricular tachycardia and one patient with ventricular tachycardia. There was no significant change in peripheral blood pressure. CONCLUSIONS: Landiolol hydrochloride has a shorter elimination half-life than any other beta-blocker, and it can be administered safely to patients with various tachyarrhythmias.

Analysis of posterior mitral annular activation during entrainment and catheter ablation of mitral isthmus ventricular tachycardia using a coronary sinus catheter.

A detailed analysis of the ventricular activation along the posterior aspect of the mitral annulus was made using a multipolar catheter positioned in the coronary sinus in a patient with mitral isthmus ventricular tachycardia (VT) associated with a remote inferior myocardial infarction and prior cryosurgical ablation for the elimination of a different preexisting VT. A change in the timing and sequence of the ventricular activation along the isthmus could be observed during induction of the VT and entrainment pacing. A radiofrequency (RF) current application directed at the posterolateral region of the isthmus successfully eliminated this tachycardia. During the RF delivery, complete conduction block was confirmed by a sudden change in the activation sequence during sinus rhythm.