Induced Pluripotent Stem Cell-Derived Cardiomyocytes with SCN5A R1623Q Mutation Associated with Severe Long QT Syndrome in Fetuses and Neonates Recapitulates Pathophysiological Phenotypes

Simple Summary

In this study, the induced pluripotent stem cell-derived cardiomyocyte model from a patient with long QT syndrome harboring a heterozygous Nav1.5 R1623Q mutation exhibited prolonged field potential duration corrected by Fridericia’s formula (FPDcF, analogous to QTcF). FPDcF was shortened with mexiletine treatment and increased the frequency of arrhythmia-like EAD events following E4031, an I_kr blocker, administration. These characteristics partly reflect the patient phenotypes. As the R1623Q mutation is related to severe congenital LQT syndrome in fetuses and neonates, the effect of the neonatal variants on the electrophysiological properties of the R1623Q mutant was examined using an automated patch-clamp system. Our results demonstrated that both R1623Q and neonatal R1623Q delayed inactivation of I_Na and increased late Na current. We speculated that neonatal Nav1.5 ameliorates QTc prolongation. Developmental switching of neonatal/adult Nav1.5 isoforms might play a role in the mechanisms underlying severe long QT syndrome in fetuses and neonates.

Abstract

The SCN5A R1623Q mutation is one of the most common genetic variants associated with severe congenital long QT syndrome 3 (LQT3) in fetal and neonatal patients. To investigate the properties of the R1623Q mutation, we established an induced pluripotent stem cell (iPSC) cardiomyocyte (CM) model from a patient with LQTS harboring a heterozygous R1623Q mutation. The properties and pharmacological responses of iPSC-CMs were characterized using a multi-electrode array system. The biophysical characteristic analysis revealed that R1623Q increased open probability and persistent currents of sodium channel, indicating a gain-of-function mutation. In the pharmacological study, mexiletine shortened FPDcF in R1623Q-iPSC-CMs, which exhibited prolonged field potential duration corrected by Fridericia’s formula (FPDcF, analogous to QTcF). Meanwhile, E4031, a specific inhibitor of human ether-a-go-go-related gene (hERG) channel, significantly increased the frequency of arrhythmia-like early after depolarization (EAD) events. These characteristics partly reflect the patient phenotypes. To further analyze the effect of neonatal isoform, which is predominantly expressed in the fetal period, on the R1623Q mutant properties, we transfected adult form and neonatal isoform SCN5A of control and R1623Q mutant SCN5A genes to 293T cells. Whole-cell automated patch-clamp recordings revealed that R1623Q increased persistent Na⁺ currents, indicating a gain-of-function mutation. Our findings demonstrate the utility of LQT3-associated R1623Q mutation-harboring iPSC-CMs for assessing pharmacological responses to therapeutic drugs and improving treatment efficacy. Furthermore, developmental switching of neonatal/adult Nav1.5 isoforms may be involved in the pathological mechanisms underlying severe long QT syndrome in fetuses and neonates.

Statement for electrophysiological procedures under the COVID-19 pandemic from the Japanese heart rhythm society task force

COVID-19 is a global catastrophe with markedly reduced health and economy of human civilization. Heart rhythm disorder has also been impacted by this disease. This statement is the universal criteria for EP procedures in the new era, which we will face during COVID-19 pandemic. We described the methods of triage based on the severity of disease, the regional state of pandemic and supply of medical resources. This guidance will be the universal criteria for EP procedures in the new era, which we will face during and after the COVID-19 pandemic.

Transvenous shock-only implantable cardioverter defibrillator after an atrio-pulmonary Fontan surgery

A 42‐year‐old woman with tricuspid atresia who underwent a Fontan surgery (atrio‐pulmonary connection) was admitted to our hospital due to symptomatic ventricular tachycardia (VT). A defibrillation lead was implanted in a distal site of a coronary vein since there was no usual entry to the ventricle. Ventricular pacing was impossible due to the high threshold, however, good sensing was obtained. Three years later, she felt palpitations and a subsequent shock therapy while climbing stairs. The cardioverter data showed that an appropriate cardioversion therapy successfully converted VT to normal rhythm.

Platelet volume indices correlate to severity of heart failure and have prognostic value for both cardiac and thrombotic events in patients with congenital heart disease

Introduction

Patients with heart failure are reported to have activated platelets leading to thrombotic events. Consequently, immature giant platelets are produced, and platelet distribution width (PDW) and mean platelet volume (MPV) increase. These platelet indices are easily, reasonably, and safely available by routine blood test and recently have been proposed as potential markers of cardiac events. However, little is known about the usefulness of platelet indices in patients with congenital heart disease (CHD).

Purpose

To test whether the hypothesis that PDW and MPV correlate to the severity of heart failure and have prognostic value in both future heart failure-related admission and thrombosis formation in patients with CHD.

Methods

We performed a retrospective, single-centre study that included 400 patients with CHD (median age, 34 years [range: 12–76]; 49% males; 35% single ventricular morphology), who were admitted in our institute between April 2014 and June 2017. We reviewed patients' medical records to assess their clinical information including medical history, blood sample data, and echocardiologic parameters. At first, we assessed the correlation between platelet indices and patients' clinical parameters. Next, we compared platelet indices before and after treatment for heart failure. Finally, using logistic regression and Kaplan-Meier analyses, we assessed prognostic factors of future heart failure-related admission and thrombosis formation.

Results

In multivariate analysis, a significant correlation was found between PDW and logBNP (brain natriuretic peptide) (p<0.001), haemoglobin (p=0.01), D-dimer (p=0.019), Fontan operation (p<0.001) and male sex (p<0.001); as well as between MPV and logBNP (p<0.001), D-dimer (p<0.001) and Fontan operation (p=0.002). Throughout treatment of heart failure, significant reduction was found both in PDW (average value before treatment = 14.2, after treatment = 13.2, p=0.002) and MPV (before = 11.2, after = 10.8, p=0.004). In multivariate logistic regression analysis, predictors of future heart failure-related admissions were PDW (hazard ratio [HR]: 1.365; 95% confidence interval [CI]: 1.005–1.768), MPV (HR: 1.472; 95% CI: 1.055–2.052), age (HR: 1.063; 95% CI: 1.010–1.119), and SpO2 under 85% (HR: 5.089; 95% CI: 1.350–19.18). Using the same analysis, predictors of thrombotic formation were PDW (HR: 1.998; 95% CI: 1.461–2.630), MPV (HR: 1.792; 95% CI: 1.155–2.781), logBNP (HR: 1.196, 95% CI: 1.085–1.320), D-dimer (HR: 1.024; 95% CI: 1.007–1.042) and male sex (HR: 3.071; 95% CI: 1.079–8.737). In addition, during median follow-up of 28 months, the Kaplan-Meier analysis showed an improvement in both heart failure and thrombosis-free survival in the low PDW, as well as the low MPV group.

Conclusion

Platelet volume indices correlate to severity of heart failure and have prognostic value for both cardiac and thrombotic events in patients with congenital heart disease.

Funding Acknowledgement

Type of funding source: None

Impact of preoperative electrophysiological intervention on occurrence of peri/postoperative supraventricular tachycardia following Fontan surgery

BACKGROUND

Little is known about the effects of preoperative electrophysiological study (EPS) and catheter ablation (CA) in Fontan surgery candidates with supraventricular tachycardia (SVT).

OBJECTIVE

The purpose of this study was to investigate the clinical impact of EPS-guided intervention in Fontan surgery candidates with preceding SVT events.

METHODS

A total of 109 consecutive patients with a history of SVT before Fontan surgery were divided into 3 groups: 44 in whom EPS with CA was attempted (CA group); 21 in whom EPS without CA was attempted (EPS group); and 44 in whom EPS was not performed (N group). The incidence and diagnosis of SVT, acute success rate of CA, and risk factors of peri/postoperative SVT were retrospectively investigated.

RESULTS

The total incidence of SVT within 1 year after Fontan surgery was 34% (n = 37), with 91% of cases occurring within 1 month. Among the 71 SVT incidences diagnosed with EPS, 31 were atrioventricular reentrant tachycardias (AVRTs) involving twin atrioventricular nodes, 12 were atrioventricular nodal reentrant tachycardias, 12 were atrial tachycardias, 7 were orthodromic AVRTs via the accessory pathway, 7 were atrial flutters, and 2 were junctional tachycardias. The acute success rate of CA was 91% (48/53). The rate of peri/postoperative atrioventricular reciprocating SVT was significantly lower in the CA group than in the N or EPS group (11% vs 43% or 43%; P <.05). No/unsuccessful CA significantly increased the risk of peri/postoperative SVT in multivariate analysis (odds ratio 4.43; 95% confidence interval 1.69-11.59).

CONCLUSION

Preoperative CA reduces peri/postoperative SVT occurrence in Fontan surgery candidates at high risk for SVT.

Acute and Long-Term Outcomes of Transvenous Cardiac Pacing Device Implantation in Patients With Congenital Heart Disease

Background: Little is known about the acute/long-term outcomes of implantation of cardiac implantable electronic devices (CIED) using a transvenous approach for patients with congenital heart disease (CHD). Methods and Results: We retrospectively investigated the acute/long-term results and complications associated with transvenous CIED implantation in 140 patients with CHD. We implanted 77 pacemakers, 51 implantable cardioverter defibrillators (ICD), and 12 cardiac resynchronization therapy (CRT) devices. Although we successfully implanted pacemakers and ICD in all patients, we could not place a coronary sinus (CS) lead in 25% of the patients requiring CRT devices due to coronary vein anomalies associated with corrected transposition of the great arteries (cTGA). Overall complication rate, lead failure rate, and incidence of device infection were 16%, 9%, and 0.7%, respectively. There was no significant difference in overall complication rates between the simple (n=22) and complex CHD (n=118) groups (14% vs. 16%). The 10-year lead survival for the ICD leads (77%) was significantly lower than for the pacemaker leads (91%, P=0.0065). Conclusions: The outcomes of transvenous CIED in patients with CHD seemed acceptable, although there was a relatively high incidence of complications. CS lead placement for cTGA may be hindered by coronary vein anomalies. Lead survival tended to be lower for ICD than for pacemakers in these patients.

Successful staged tricuspid valve replacement following cardiac resynchronization therapy in a congenitally corrected transposition of the great arteries

Simple tricuspid valve surgery for complex heart disease with systemic right ventricular dysfunction is a high-risk procedure; however, staged tricuspid valve surgery following cardiac resynchronization therapy seems to be a beneficial method to expect reverse systemic ventricular remodeling.

Direct observation of orientation distributions of actin filaments in a solution undergoing shear banding

Shear banding is frequently observed in complex fluids. However, the configuration of macromolecules in solutions undergoing shear banding has not yet been directly observed. In this study, by using the fact that F-actin solutions exhibit shear banding and actin filaments are visualized by fluorescent labels, we directly observed the intrinsic states of an actin solution undergoing shear banding. By combining the 3D imaging of labeled actin filaments and particle image velocimetry (PIV), we obtained orientation distributions of actin filaments in both high and low shear rate regions, whose quantitative differences are indicated. In addition, by using the orientation distributions and applying stress expression for rod-like polymers, we estimated stress tensors in both high and low shear rate regions. This evaluation indicates that different orientation distributions of filamentous macromolecules can exhibit a common shear stress.

Long-Term Efficacy of Implantable Cardioverter Defibrillator in Repaired Tetralogy of Fallot - Role of Anti-tachycardia Pacing

BACKGROUND

Tetralogy of Fallot (TOF) is one of the common congenital heart diseases (CHD) in implantable cardioverter defibrillator (ICD) recipients, but few studies have reported the long-term outcomes of and the anti-tachycardia pacing (ATP) efficacy in repaired TOF.Methods and Results:Twenty-one repaired TOF patients with an ICD implanted between April 2003 and March 2015 were investigated retrospectively. ICD therapy and clinical outcome were analyzed. Mean patient age was 39±11 years; 62% were male; and mean age at repair surgery was 9.4±6.8 years. During a median follow-up of 5.6 years (range, 2.6-8.4 years), no patients died. Appropriate ATP were delivered in 11 patients (52%), with appropriate shocks in 5 patients (24%) and inappropriate shocks in 5 patients (24%). The success rate of ATP was 98% for fast ventricular tachycardia (VT; cycle length ≤320 ms) and 98% for slow VT (cycle length >320 ms). ATP effectiveness increased from 81.5% with the first ATP attempt to 93.7% with the second ATP attempt, to 97.5% with the third ATP attempt, and to 98.6% with the fourth or successive ATP attempt (P<0.0001, Cochran-Armitage trend test).

CONCLUSIONS

ATP was highly effective in repaired TOF regardless of VT cycle length. Multiple ATP attempts could have an important role in VT termination, and the novel subcutaneous ICD without ATP capability should be used carefully.

High prevalence of cardiovascular risk factors in children and adolescents with Williams-Beuren syndrome

Background

A high incidence of cardiovascular (CV) risk factors has been reported in adults with Williams-Beuren syndrome (WS). However, the prevalence of these factors in children and adolescents with WS is unknown. Therefore, the purpose of this study was to evaluate the prevalence of CV risk factors in these patients.

Methods

Thirty-two WS patients aged <18 years were enrolled in the study. Oxidized low-density lipoprotein levels (n = 32), oral glucose tolerance test results (n = 20), plasma renin and aldosterone levels (n = 31), 24-h ambulatory blood pressure (ABP; n = 24), carotid artery intima-media thickness (IMT; n = 15), and brachial artery flow-mediated dilatation (FMD; n = 15) were measured and analyzed.

Results

The lipid profile revealed hypercholesterolemia in 22 % and elevated oxidized low-density lipoprotein levels in 94 % of the patients. Glucose metabolism abnormalities were found in 70 % of the patients. Insulin resistance was observed in 40 % of the patients. High plasma renin and aldosterone levels were detected in 45 and 39 % of the patients, respectively. A mean systolic blood pressure above the 90th percentile was noted in 29 % of patients. High IMT (>0.65 mm) and low FMD (<9 %) were detected in 80 and 73 % of patients, respectively.

Conclusion

In patients with WS, CV risk factors are frequently present from childhood. In children with WS, screening tests for the early detection of CV risk factors and long-term follow-up are required to determine whether long-term exposure to these factors increases the risk for CV events in adulthood.

Incidence, Clinical Course, and Risk Factors of Amiodarone-Induced Thyroid Dysfunction in Japanese Adults With Congenital Heart Disease

BACKGROUND

Although amiodarone (AMD)-induced thyroid dysfunction (AITD) is an important complication of AMD therapy, little is known about AITD in adult Japanese patients with congenital heart disease (CHD).

METHODS AND RESULTS

We retrospectively studied 131 adult patients with CHD who were on low-dose AMD (median, 150 mg/day). The median patient age was 28 years, and the median follow-up was 44 months. The incidence, clinical course, and risk factors of AITD, including AMD-induced thyrotoxicosis (AIT) and AMD-induced hypothyroidism (AIH), were evaluated. The total incidence of AITD was 30% (AIT: 18%, n=24; AIH: 12%, n=16). Approximately 67% of patients with AIT displayed deterioration of tachyarrhythmia, and 38% patients underwent steroid therapy. Although thyroid function and symptoms associated with AIT improved within 6 months after diagnosis in most patients with AIT (92%), 1 patient died suddenly during an acute phase of AIT. No patient with AIH exhibited deterioration of tachyarrhythmia, and 9 patients underwent thyroid hormone replacement therapy. Cox multivariate analysis identified no independent risk factor for AIT, whereas liver dysfunction (hazard ratio 2.573; 95% confidence interval 1.102-5.795) was an independent risk factor for AIH.

CONCLUSIONS

AITD commonly occurred in adult Japanese patients with CHD even though they were on a low-dose AMD regimen. Risk factors for AITD may vary according to ethnicity and diet.

Successful Fontan conversion combined with cardiac resynchronization therapy for a case of failing Fontan circulation with ventricular dysfunction

Although Fontan conversion combined with cardiac resynchronization therapy appears to be an effective surgical solution for the management of failing Fontan circulation with refractory atrial arrhythmia and cardiac dysfunction due to dyssynchronous ventricular wall motion, limited data are available on the mid- to long-term results of this treatment. We report our successful experience with Fontan conversion combined with cardiac resynchronization therapy in a male patient with failing Fontan circulation who showed favourable outcomes 5 years after the operation.

Alcohol consumption promotes the intestinal translocation of Streptococcus suis infections

Streptococcus suis is an emerging zoonotic agent. This study aimed to investigate whether S. suis is likely to translocate across the intestines of human hosts who have liver disease and/or consume alcohol. Both the alcoholism and cirrhosis models exhibited high mRNA expression of TGF and collagen1, but only the cirrhosis model had fibrosis in the liver. After both models were infected with S. suis, significantly different concentrations of S. suis were detected in the blood and brains of the alcoholism model (Blood: 36.4%; Brain: 31.8%) and the cirrhosis model (Blood: 62.5%; Brain: 62.5%) compared to the concentrations in the healthy mice (Blood: 15.4%; Brain: 0%). Trans-epithelial electrical resistance (TER) was used to examine the Caco-2 cells in the in vitro that had an S. suis infection combined with 1% ethanol. Although the ethanol did not influence the Caco-2 cells' barriers, it did rapidly decrease the barriers' TER value and then their E-cadherin compared to the infected Caco-2 cells without the ethanol treatment. Immunofluorescence also indicated that the barriers of the Caco-2 cells treated with ethanol were disrupted and that S. suis translocated from the apical to the basolateral side. This study demonstrated that alcohol consumption helped S. suis to translocate.

Pacing device therapy in infants and children: a review

The number of pediatric pacemakers implanted is still relatively small. Children requiring pacing therapy have characteristics that are distinct from those of adults, including physical size, somatic growth, and cardiac anomalies. Considering these features, long-term follow-up of pediatric pacemaker implantation is necessary. Selection of appropriate generators, pacing modes, pacing sites, and leads is important. Generally, epicardial leads are commonly used in small infants. On the other hand, the use of endocardial leads in children is increasing worldwide because of their benefits over epicardial leads, such as minimal invasiveness, lower pacing threshold, and longer generator longevity. Endocardial leads are not suitable for patients with intracardiac shunts because of the high risk of systemic thrombosis. Venous occlusion is another significant problem with endocardial leads. With the increase in the number of pacing device implantations, the incidence of infection from such devices is also increasing. Complete device removal is sometimes recommended to treat device infection, but experience in the removal of endocardial leads in children is still scarce. This article gives an overview of pacing therapy in the pediatric population, including discussions on new pacing systems, such as remote monitoring systems, magnetic imaging compliant pacemaker systems, and leadless pacing devices.

Congenital giant cardiac tumor with severe left-ventricular inflow and outflow obstruction and arrhythmia treated with pulmonary artery banding and long-term amiodarone infusion

We report a congenital giant cardiac tumor that occupied the majority of left ventricular cavity with severe left ventricular inflow and outflow obstruction. The hemodynamics were similar to univentricular physiology. He was treated with prostaglandins and bilateral pulmonary artery banding. He had frequent supraventricular tachycardia associated with ventricular pre-excitation that was controlled by long-term administration of intravenous amiodarone. The patient died due to sepsis after 3 months.

Range and Damage Distribution in Cluster Ion Implantation

Cluster ion implantation is an attractive alternative to conventional ion implantation, particularly for shallow junction formation. It is easy to obtain high-current ion beams with low equivalent energy using cluster ion beams. The implanted boron distribution in 5keV B10H14 implanted Si is markedly shallower than that in 5keV BF2 ion implanted Si. The implanted depth is less than 0.04 μm, indicating that cluster ion implantation is capable of forming shallow junctions. The sheet resistance of 3keV B10H14 implanted samples falls below 500 Ω/sq after annealing at 1000°C for 10s. Shallow implantation can be realized by a high energy cluster beam without space-charge problems in the incident beam. Defect formation, resulting from local energy deposition and multiple collisions, is unique for cluster ions. The thickness of the damaged layer formed by cluster ion bombardment increases with the size of the cluster, if implant energy and ion dose remain constant. This is one of the nonlinear “cluster effects,” which may allow some control over the implant damage distributions that accompany implanted ions, and which have been shown to have a great effect on dopant redistribution during annealing

The associations between socio-economic status and major depressive disorder among Blacks, Latinos, Asians and non-Hispanic Whites: findings from the Collaborative Psychiatric Epidemiology Studies

BACKGROUND

This study examined whether there were associations between individual measures of socio-economic status (SES) and the 12-month prevalence of major depressive disorder (MDD) in representative samples of Blacks, Latinos, Asians and Whites in the USA.

METHOD

The data used were from the Collaborative Psychiatric Epidemiology Studies (CPES).

RESULTS

There was an association between household income and MDD among Whites. However, the association was not statistically significant. Statistically significant associations were present between educational attainment and MDD among Whites. Among both Whites and Latinos, being out of the labor force was significantly associated with MDD. In analyses by nativity, being out of the labor force was significantly associated with MDD among US-born and foreign-born Latinos.

CONCLUSIONS

Significant associations between various measures of SES and MDD were consistently observed among White and, in some cases, Latino populations. Future studies should continue to examine sociopsychological factors related to SES that increase the risk of MDD among people from racial-ethnic communities.

Significance of repeated resection for recurrent intrahepatic cholangiocarcinoma

BACKGROUND/AIMS

Management of patients with recurrent intrahepatic cholangiocarcinoma (ICC) following surgical resection is difficult, and surgical resection is rarely indicated. We retrospectively reviewed patients with recurrent intrahepatic cholangiocarcinoma.

METHODOLOGY

Between April 1998 and March 2007, 57 consecutive patients with ICC underwent surgical resection. Mode of recurrence and treatment of recurrent tumors, especially surgical resection for these tumors, in patients with cancer recurrence were evaluated.

RESULTS

37 (65%) patients experienced tumor recurrence. Out of these patients, 24 underwent some type of cancer-directed therapy, including 9 patients (24%) for whom surgical resection was attempted: the latter included 4 hepatic resections, 2 pulmonary resections, 2 tumor resections, and 1 gastric resection. For 6 patients with recurrent tumor in the liver or the lung, microscopic complete resection was achieved, while incomplete resection was resulted in the remaining 3 patients. No postoperative mortality was encountered. Among patients with complete resection, 3 are alive without disease 32, 39 and 77 months after the second operation, one has lived with disease for 13 months, and 2 died of disease after 22 and 26 months. No significant difference in overall survival was observed between patients undergoing primary and second surgical resections, calculated from the primary and the second operations, respectively.

CONCLUSIONS

Repeated surgical resection for recurrent ICC can be performed with acceptable morbidity, and affords selected patients a chance for long-term survival.

Abnormal Tissue Doppler Images are Associated With Elevated Plasma Brain Natriuretic Peptide and Increased Oxidative Stress in Acute Kawasaki Disease

BACKGROUND

The aims of this study were to evaluate myocardial mechanics using pulsed tissue Doppler imaging (TDI), and to determine the relationship between abnormal myocardial performance and plasma brain natriuretic peptide (BNP) levels and oxidative stress in acute Kawasaki disease (KD).

METHODS AND RESULTS

Consecutive TDI parameters, including peak systolic velocity (Sw) and early (Ew) and late diastolic excursion of the mitral annuli were obtained in 42 patients with KD (mean age: 2.4+/-0.4 years) in weeks 1, 2, and 3, and during convalescence. Plasma BNP level and urinary 8-isoprostane were also examined during the acute phase. These data were then compared with TDI profiles from 62 healthy children, plasma BNP levels in 38 controls with other febrile illnesses, and urinary 8-isoprostane levels in 13 healthy children. Ew in week 1 was significantly lower than in controls, subsequently normalizing in the convalescent stage. Plasma BNP level in acute KD patients was significantly higher (65+/-9 pg/ml) than in controls (13+/-2 pg/ml). Urinary 8-isoprostane level in acute KD patients was significantly higher as compared with control (596 +/-37 vs 379+/-26 pg/ml Cr, p<0.05). There was a significant negative correlation between week 1 Sw and plasma BNP level (r=-0.55, p=0.0001). Change in Sw velocity in the BNP >/=51 group was significantly greater than in the BNP <51 group. There was a significant negative correlation between week 1 Sw and urinary 8-isoprostane level (r=-0.48, p=0.001).

CONCLUSIONS

Latent abnormal tissue Doppler profiles, possibly reflecting long-axis systolic and diastolic dysfunction have been noted in KD patients. Abnormal myocardial mechanics may contribute to the increased plasma BNP level and enhanced oxidative stress may contribute to cardiac dysfunction in KD.

Alkene/diamond liquid/solid interface characterization using internal photoemission spectroscopy

The photochemical attachment of 10-amino-dec-1-ene molecules protected with a trifluoroacetic acid group (TFAAD) on hydrogen-terminated single-crystalline chemical vapor deposited (CVD) diamond is characterized by total photoyield spectroscopy (TPYS), conductivity, Hall-effect, spectrally resolved photoconductivity (SPC), optical transmission experiments, and, for the first time, by in situ internal photoemission (IPE) spectroscopy applied in the spectral regime from 4 to 6 eV on the alkene/diamond (liquid/solid) heterostructures. These experiments are performed on undoped, (100) oriented, single-crystalline CVD diamond films, which contain no grain boundaries and have negligible bulk and surface defect densities. X-ray photoelectron spectroscopy (XPS) is used to investigate the chemical bonding of alkene molecules to diamond. The spectroscopic set of data shows that the photochemical reaction window of H-terminated diamond is shifted below the optical gap of diamond because of the negative electron affinity. In situ IPE experiments reveal electron emission between 4.5 and 5.2 eV. A model is introduced and discussed in which valence-band electrons are optically excited into empty hydrogen-induced surface states of diamond from where they tunnel into empty pi states of alkene molecules. We theoretically discuss the fastest attachment time to achieve a saturated TFAAD layer of about 2 x 10(14) cm(-)(2) on diamond, which is experimentally detected to be 7 h. In the case of direct optical electron excitations from diamond, the bonding efficiency will be one TFAAD molecule attachment arising from about 1600 emitted electrons.

Evaluation of right ventricular performance long after the atrial switch operation for transposition of the great arteries using the Doppler Tei index

Right ventricular (RV) dysfunction may occur in patients after the atrial switch operation for d-transposition of the great arteries (d-TGA) and can be an important complication. Noninvasive assessment of RV function using echocardiography is necessary for following up these patients. We evaluated RV function using the Doppler Tei index (RV Tei index). The RV Tei index measures the ratio of total time intervals in isovolumetric contraction and relaxation to the ejection time. The subjects consisted of 33 patients who had undergone the atrial switch operation for d-TGA (the atrial switch group) (mean age, 21 +/- 4 years), 10 patients with pulmonary artery stenosis after the arterial switch operation for d-TGA (the arterial switch group) (mean age, 17 +/- 1 years), and 10 patients with a normally structured heart as a control group (mean age, 26 +/- 7 years). The RV Tei index (0.65 +/- 0.16) was significantly higher in the atrial switch group than in the arterial switch group (0.29 +/- 0.07) and the control group (0.29 +/- 0.01) (p < 0.05). The fractional area change of the RV obtained from the four-chamber view in the atrial switch group showed a significant negative correlation with the RV Tei index (r = -0.58, p < 0.01). The RV Tei index increased with increasing severity of the NYHA functional class. In the moderate/severe tricuspid regurgitation group, it was significantly higher than in patients with none/trivial tricuspid regurgitation. We conclude that the RV Tei index is useful for evaluating RV junction long after the atrial switch operation for d-TGA.

In vivo reopening of the neonatal ductus arteriosus by a prostanoid EP4-receptor agonist in the rat

Prostaglandin E1 is used to reopen the constricted ductus arteriosus in neonates with ductus-dependent circulation. To clarify possible prostanoid receptor agonists that can reopen the neonatal ductus with fewer side effects, we studied in vivo reopening of the neonatal ductus arteriosus by AE1-329, a prostanoid EP4-receptor agonist, in the rat. Neonatal rats were incubated at 33 degrees C. The inner diameter of the ductus was measured with a microscope and a micrometer following rapid whole-body freezing. Intraesophageal pressure was measured with a Millar micro-tip transducer. The ductus arteriosus constricted quickly after birth, and the inner diameter was 0.80 and 0.08 mm at 0 and 60 min after birth. PGE1 and AE1-329, injected subcutaneously at 60 min after birth, dilated the ductus dose-dependently. Thirty minutes after injection of 10 ng/g of PGE1 and AE1-329, the ductus diameter was 0.52 and 0.65 mm, respectively. The ductus-dilating effect of PGE1 was maximal at 15-30 min, and disappeared at 2 h. The ductus-dilating effect of AE1-329 was prolonged, the ductus was widely open at 6 h, and closed at 12 h after injection of 10 ng/g AE1-329. AE1-259-01 (EP2 agonist) (100 ng/g) did not dilate the neonatal ductus. Respiration was depressed by PGE1, but not by AE1-329. These results indicate the major role of EP4 in the neonatal ductus and that AE1-329, an EP4 agonist, can be used to dilate the neonatal constricted ductus without the side effects shown by EP3, including apnea.

In vivo constriction of the fetal and neonatal ductus arteriosus by a prostanoid EP4-receptor antagonist in rats

Indomethacin is used to constrict the patent ductus arteriosus in premature infants. To clarify possible prostanoid receptor antagonists that can constrict the ductus, we studied in vivo constriction of the fetal and neonatal ductus arteriosus by AE3-208, a prostanoid EP4-receptor antagonist, in rats. Following quick cesarean section of near-term pregnant rats (21 d), neonates were incubated in room air at 33 degrees C. The inner diameter of the ductus was measured with a microscope and a micrometer following rapid whole-body freezing of the fetus and neonate, and sectioning of the thorax in the frontal plane on a freezing microtome. In the control, the ductus arteriosus constricted quickly after birth, and the inner diameter was 0.80 mm in the fetus and 0.06 mm at 90 min after birth. AE3-208, administered orogastrically to the dam, constricted the fetal ductus dose dependently. Maximal ductal constriction was observed 4 h after administration, and the ductal diameters were 0.06 mm and 0.26 mm after administration of 10 mg/kg and 10 ng/kg of AE3-208, respectively. In neonatal rats, AE3-208 injected subcutaneously at 30 min after birth, inhibited dilatation of the ductus by PGE1 dose dependently. PGE1 (10 microg/kg) was injected subcutaneously to the 1-h-old neonatal rat, and the ductal diameters were 0.53 mm and 0.19 mm without and with pretreatment of AE3-208 (10 microg/kg), respectively. These results indicate the major role of EP4 in the fetal and neonatal ductus and show that an EP4 antagonist can be used to constrict the patent ductus of premature infants.

Effect of decreased umbilical blood flow and hemorrhage, and decreased prostaglandins on the ductus venosus diameter in the rat

BACKGROUND

The closing mechanisms of the ductus venosus (DV) have not yet been revealed.

OBJECTIVES

The aims of this study were to document the perinatal closing process of the DV, to study the suppression of prostaglandins by indomethacin, and to determine the effects of umbilical blood flow to the fetal DV.

METHODS

The proximal and distal DV diameters were studied in near-term fetal and neonatal rats with the rapid whole-body freezing method.

RESULTS

The DV diameter changed sensitively at birth, and decreased by 10% immediately after the cessation of the umbilical circulation. Umbilical hemorrhage caused an additional decrease in the DV diameter compared with neonate without the hemorrhage. The neonates showed a DV diameter decreased by 20% at 30 min and 30% at 60 min after birth. The fetal DV was tubular, and the neonatal DV was horn-shaped with a smaller inlet than outlet. A small dose (0.1 mg/kg) of indomethacin administered to the pregnant rats induced a reduction in prostaglandins and decreased the fetal DV diameter to 80% of the control. Indomethacin at a large dose (10 mg/kg), administered to the dams, induced a reduction in prostaglandins, severe constriction of the ductus arteriosus, and decreased blood flow through the descending aorta umbilicus, and caused a further reduction in the DV diameter to 70-80% of the control. A large dose of nifedipine (10 mg/kg), which causes cardiac suppression and heart failure in the fetus, was administered to near-term rats to study the effect of decreased fetal cardiac output and blood flow passing through the DV. Nifedipine induced a 20% decrease in the DV diameter for 2-8 h. In all 1-hour-old neonates with or without pretreatment, the inlet diameter of the DV was reduced more than the outlet diameter, and the DV showed a horn-shaped morphology.

CONCLUSION

In conclusion, perinatal cessation of the umbilical circulation and umbilical hemorrhage are associated with an immediate decrease in DV diameter. The DV diameter is also reduced in other conditions associated with decreased umbilical blood flow, such as induced by nifedipine which leads to heart failure and constricting of the ductus arteriosus induced by indomethacin. The constricting effect of a small dose of indomethacin suggests that prostaglandins dilate the DV physiologically.

[Left ventricular function in adult patients after the atrial switch operation for transposition of the great arteries]

OBJECTIVES

Right ventricular function may deteriorate after the atrial switch operation in patients with transposition of the great arteries, but the effect on left ventricular function is unknown. Chronic left ventricular function was evaluated in adult patients after the atrial switch operation for transposition of the great arteries.

METHODS

Right and left ventricular functions were evaluated using data from cardiac catheterization performed in nine patients older than 17 years who had undergone the atrial switch operation for transposition of the great arteries. The mean age at operation was 19 +/- 16 months and the age at catheterization ranged from 17 to 32 years (mean age 23 +/- 5 years). Echocardiography was performed in all patients to evaluate tricuspid regurgitation. Myocardial perfusion studies using technetium-99 m-tetrofosmin were assessed in five patients.

RESULTS

Mean right ventricular end-diastolic volume was slightly increased to 122 +/- 27% of the normal value and mean right ventricular ejection fraction was depressed to 44 +/- 5% of the normal value. Left ventricular ejection fraction ranged from 37% to 63% (mean 50 +/- 7%) and was under 50% in four of the nine (44%) patients. Right ventricular ejection fraction was positively correlated with left ventricular ejection fraction(r = 0.72, p < 0.05). All patients had tricuspid regurgitation, mild in four, moderate in four, and severe in one patient. Left ventricular ejection fraction was lower in patients with moderate or severe tricuspid regurgitation(54 +/- 4%) than in patients with mild tricuspid regurgitation(47 +/- 6%, p < 0.05). Mild or moderate perfusion abnormalities were observed in all patients (five of five) who underwent myocardial perfusion studies. Mean right and left ventricular ejection fractions were 43 +/- 3% and 50 +/- 3%, respectively, in patients who underwent myocardial perfusion study, which were under the normal levels.

CONCLUSIONS

Left ventricular dysfunction is common in adult patients after the atrial switch operation for transposition of the great arteries. Some right ventricular abnormalities may correlate with the left ventricular dysfunction.