Erratum: Linear Optical Quantum Computation with Frequency-Comb Qubits and Passive Devices [Phys. Rev. Lett. 130, 200602 (2023)].

This corrects the article DOI: 10.1103/PhysRevLett.130.200602.

Quantum frequency conversion using 4-port fiber-pigtailed PPLN module.

Quantum frequency conversion (QFC), which involves the exchange of frequency modes of photons, is a prerequisite for quantum interconnects among various quantum systems, primarily those based on telecom photonic network infrastructures. Compact and fiber-closed QFC modules are in high demand for such applications. In this paper, we report such a QFC module based on a fiber-coupled 4-port frequency converter with a periodically poled lithium niobate (PPLN) waveguide. The demonstrated QFC shifted the wavelength of a single photon from 780 to 1541 nm. The single photon was prepared via spontaneous parametric down-conversion (SPDC) with heralding photon detection, for which the cross-correlation function was 40.45 ± 0.09. The observed cross-correlation function of the photon pairs had a nonclassical value of 13.7 ± 0.4 after QFC at the maximum device efficiency of 0.73, which preserved the quantum statistical property. Such an efficient QFC module is useful for interfacing atomic systems and fiber-optic communication.

Linear Optical Quantum Computation with Frequency-Comb Qubits and Passive Devices.

We propose a linear optical quantum computation scheme using time-frequency degrees of freedom. In this scheme, a qubit is encoded in single-photon frequency combs, and manipulation of the qubits is performed using time-resolving detectors, beam splitters, and optical interleavers. This scheme does not require active devices such as high-speed switches and electro-optic modulators and is robust against temporal and spectral errors, which are mainly caused by the detectors' finite resolution. We show that current technologies almost meet the requirements for fault-tolerant quantum computation.

Entanglement distribution using a biphoton frequency comb compatible with DWDM technology.

We demonstrate a distribution of frequency-multiplexed polarization-entangled photon pairs over 16 frequency channels using demultiplexers for the signal and idler photons with a frequency spacing of 25 GHz, which is compatible with dense wavelength division multiplexing (DWDM) technology. Unlike conventional frequency-multiplexed photon-pair distribution by a broadband spontaneous parametric down-conversion (SPDC) process, we use photon pairs produced as a biphoton frequency comb by SPDC inside a cavity where one of the paired photons is confined. Owing to the free spectral range of 12.5 GHz and the finesse of over 10 of the cavity, the generated photons having a narrow linewidth in one channel are separated well from those in the other channels, which minimizes channel cross-talk in advance. The observed fidelities of the photon pairs range from 81 % to 96 % in the 16 channels. The results show the usefulness of the polarization-entangled biphoton frequency comb for frequency-multiplexed entanglement distribution via a DWDM system.

Efficacy of a phosphodiesterase type 5 inhibitor on the pulmonary artery index and postoperative hemodynamics after a Fontan operation.

There have been no reports regarding the influence of a change in the pulmonary artery index before or after a Fontan operation. Moreover, the factors that might affect the change in the pulmonary artery index are unclear. This was a retrospective study, which included 94 patients who underwent a Fontan operation. We divided the patients into two groups according to the change in the pulmonary artery index before and after the Fontan operation: the increased pulmonary artery index group (n = 51) and decreased pulmonary artery index group (n = 43). The pulmonary artery index after the Fontan operation was significantly higher in the increased pulmonary artery index group than decreased pulmonary artery index group (p < 0.0001). The central venous pressure (p < 0.0001) and pulmonary vascular resistance (p = 0.007) were significantly lower in the increased pulmonary artery index group. The mixed venous oxygen saturation was significantly higher in the increased pulmonary artery index group (p < 0.0001). The pulmonary artery index was more increased in the patients who were administered a phosphodiesterase type 5 inhibitor than in those who were not (p = 0.03). The change in the pulmonary artery index reflected the hemodynamics after a Fontan operation during the short term. In that respect, phosphodiesterase type 5 inhibitors might be involved in the process.

Effects of step frequency during running on the magnitude and symmetry of ground reaction forces in individuals with a transfemoral amputation.

BACKGROUND: Individuals with unilateral transfemoral amputation are prone to developing health conditions such as knee osteoarthritis, caused by additional loading on the intact limb. Such individuals who can run again may be at higher risk due to higher ground reaction forces (GRFs) as well as asymmetric gait patterns. The two aims of this study were to investigate manipulating step frequency as a method to reduce GRFs and its effect on asymmetric gait patterns in individuals with unilateral transfemoral amputation while running. METHODS: This is a cross-sectional study. Nine experienced track and field athletes with unilateral transfemoral amputation were recruited for this study. After calculation of each participant's preferred step frequency, each individual ran on an instrumented treadmill for 20 s at nine different metronome frequencies ranging from - 20% to + 20% of the preferred frequency in increments of 5% with the help of a metronome. From the data collected, spatiotemporal parameters, three components of peak GRFs, and the components of GRF impulses were computed. The asymmetry ratio of all parameters was also calculated. Statistical analyses of all data were conducted with appropriate tools based on normality analysis to investigate the main effects of step frequency. For parameters with significant main effects, linear regression analyses were further conducted for each limb. RESULTS: Significant main effects of step frequency were found in multiple parameters (P < 0.01). Both peak GRF and GRF impulse parameters that demonstrated significant main effects tended towards decreasing magnitude with increasing step frequency. Peak vertical GRF in particular demonstrated the most symmetric values between the limbs from - 5% to 0% metronome frequency. All parameters that demonstrated significant effects in asymmetry ratio became more asymmetric with increasing step frequency. CONCLUSIONS: For runners with a unilateral transfemoral amputation, increasing step frequency is a viable method to decrease the magnitude of GRFs. However, with the increase of step frequency, further asymmetry in gait is observed. The relationships between step frequency, GRFs, and the asymmetry ratio in gait may provide insight into the training of runners with unilateral transfemoral amputation for the prevention of injury.

Successful Ablation of a Biatrial Tachycardia from the Superior Vena Cava after a Senning Operation for Complete Transposition of the Great Arteries.

The Senning operation used to be widely performed for an intracardiac repair in a complete transposition of the great arteries. During the long-term follow-up, supraventricular tachycardia (SVT) is often observed because of the complex suture lines. The typical mechanism of a Senning-related SVT is cavo-tricuspid isthmus-dependent atrial flutter. On rare occasions, complex SVTs (e.g., biatrial tachycardia (BiAT)) whose diagnosis and treatment are challenging, may occur. We report a rare case of a BiAT following a Senning operation that was successfully ablated from the superior vena cava, and the local activation time histogram module (CARTO3 V7 module [Biosense Webster, Irvine, CA, USA]) was crucial for analyzing the complex circuit.

Ultrahigh density atrio-ventricular dual-chamber mapping as a next generation tool for ablation of accessory pathways.

INTRODUCTION: Detailed three-dimensional (3D) mapping has been useful for effective radiofrequency catheter ablation. The Rhythmia system can create atrio-ventricular dual-chamber mapping, which reveals the atrial and ventricular potentials all at once in the same map. The aim of this study was to investigate the utility of mapping the atrium and ventricle simultaneously with a high-density 3D mapping system for the ablation of accessory pathways (AP). METHODS: From July 2015 to August 2020, 111 patients underwent ablation of APs. Dual-chamber maps were created in 50 patients (median age 15 [10-54], 32 male [64.0%]), while 61 patients underwent radiofrequency (RF) ablation with conventional single-chamber 3D maps. The background characteristics and procedural details were compared between the dual-chamber mapping group and the conventional single-chamber mapping group. RESULTS: The number of RF applications (median [IQR]; 1.0 [1.0-3.0] vs. 3.0 [1.0-6.0], p = .0023), RF time (median [IQR], s; 9.2 [2.0-95.7] vs. 95.6 [4.1-248.7], p = .0107), and RF energy (median [IQR], J; 248.4 [58.7-3328.2] vs. 2867.6 [134.2-7728.4], p = .0115) were significantly lower in the dual-chamber group. The fluoroscopy time (median [IQR], min; 19.9 [14.2-26.1] vs. 26.5 [17.7-43.4], p = .0025) and fluoroscopy dose (median [IQR], mGy; 52.5 [31.3-146.0] vs. 119.0 [43.7-213.5], p = .0249) were also significantly lower in the dual-chamber than single-chamber mapping group. CONCLUSION: The dual-chamber mapping was useful for ablating accessory pathways and reducing the number of RF applications, total RF energy, and radiation exposure as compared with traditional mapping techniques.

Efficacy and safety of tolvaptan after pediatric congenital heart disease surgery.

It is not clear whether tolvaptan is safe and effective irrespective of various underlying clinical conditions including the functional ventricle morphology, chromosomal abnormalities, and renal function after complex pediatric congenital heart disease surgery. Also, the appropriate dose of tolvaptan in these patients has not been previously identified. We retrospectively assessed the urine volume, body weight, patient clinical characteristics, laboratory data, and vital signs before and on days 1 and 7 of the tolvaptan administration after congenital heart disease surgery. Also, we assessed the relationship between the tolvaptan dose and its effects. A total of 86 patients were included the study. The mean time from the surgery to the tolvaptan administration was 23.5 ± 3.7 days. After administering tolvaptan, the urine volume significantly increased and body weight significantly decreased from baseline by days 1 and 7 (p < 0.0001). The urine volume significantly increased more in the survivors than the deceased. Of the 22 patients who had low serum sodium concentrations at baseline, 20 had an increased serum sodium concentration on day 7. The clinical effect of tolvaptan was not affected by the functional ventricle morphology, chromosomal abnormalities, or renal function. There was a positive correlation between the tolvaptan dose and change in the urine volume until a tolvaptan dose of up to 0.3 mg/kg/day but not at more than 0.3 mg/kg/day. Tolvaptan administration is safe and effective after congenital heart disease surgery irrespective of various underlying clinical conditions. Though the urine volume tends to increase until a tolvaptan dose of up to 0.3 mg/kg/day in pediatric congenital heart disease patients, there was no further benefit with more than 0.3 mg/kg/day.

Clinical trial of the CP stent for pulmonary artery stenosis: the first investigator-initiated clinical trial for pediatric interventional cardiology in Japan.

Stenting is an important treatment option for pulmonary artery stenosis (PS) associated with congenital heart disease (CHD). However, no stent has been approved for this indication in Japan, despite negotiation between academia and the regulatory bodies for longer than 20 years. To evaluate efficacy and safety of the CP stent, we performed the first investigator-initiated clinical trial for pediatric interventional cardiology in Japan. This trial was designed as a single-arm, prospective, clinical trial. Patients who had postoperative PS associated with CHD were included. Stenting was attempted in 24 cases and succeeded in 22 cases. The median age of the patients was 11 years (3-36 years) and weight was 38 kg (12-69 kg), while follow-up for 12 months was completed. In all 22 cases, stenting was successful, with a 50% increase in the minimum lumen diameter (MLD) in 86.4% of patients (90% confidence interval, 68.4-96.2%). The mean percent change in MLD was 119.3 ± 52.5%. In two-ventricle repair, the mean percent change in systolic right ventricular/aortic pressure was - 8.5 ± 16.1%, while that of pressure gradient was - 55.9 ± 41.7%. In single-ventricle repair, the percent change in the mean pressure gradient was - 100.0 ± 0%, while that of SaO2 was 1.4 ± 1.7%. No serious adverse events or significant restenosis was reported. The CP stent is highly effective and safe for PS associated with CHD. This study has significant importance in not only scientific but also social considerations.

Late recovery of the cardiopulmonary exercise capacity after transcatheter amplatzer device closures for atrial septal defects in adults.

Transcatheter atrial septal defect (ASD) closures using an Amplatzer Septal Occluder (ASO) have been widely performed. Compared to children, we sometimes experience late recovery of exercise performance in adult patients. Our study aimed to evaluate the change in the cardiopulmonary exercise capacity in asymptomatic or mildly symptomatic adult patients after a transcatheter ASD closure using an ASO. The subjects consisted of 29 patients (age 39.5 ± 13.6 years) that underwent cardiopulmonary exercise testing (CPX) before, 3, 6, and 12 months after a transcatheter secundum ASD closure using an ASO. The peak oxygen consumption (peak VO2), anaerobic threshold (AT), and slope of the correlation between the ventilation and carbon dioxide production (VE/VCO2 slope) were evaluated. We also evaluated the left-ventricular end-diastolic diameter (LVEDD), right-ventricular end-diastolic dimension (RVEDD) by echocardiography, and hemodynamic values by cardiac catheterization before the ASO procedure. The peak VO2 did not show any improvement 3 months after the ASO procedure; however, a significant improvement was displayed 6 and 12 months (baseline: 23.4 ± 6.3, 3 months: 23.6 ± 6.4, 6 months: 25.1 ± 5.6, 12 months: 26.4 ± 5.3 mL/kg/min; p < 0.001) after the ASO. The LVEDD (before: 38.1 ± 3.6, 3 months: 43.4 ± 3.4 mm; p < 0.001) and RVEDD (before: 33.6 ± 5.3, 3 months: 26.3 ± 2.6 mm; p < 0.001) on echocardiography quickly improved 3 months after the ASO. Although the LVEDD and RVEDD normalized 3 months after the ASO, the peak VO2 still decreased; however, the peak VO2 improved to almost a normal range 6 months after the ASO.

Efficacy of a Subcutaneous Implantable Cardioverter Defibrillator in a Child with Early Repolarization Syndrome.

An early repolarization (ER) pattern or J waves are considered to be a benign finding observed in the healthy population, however, it has been pointed out that the ER pattern seen in the inferolateral leads could be an independent risk factor for fatal arrhythmias. We present a pediatric case in which early repolarization syndrome (ERS) was suspected due to the presence of ER or J waves in the inferior leads, which eventually disappeared after the administration of pilsicainide. During the follow-up period, several fatal ventricular arrhythmias were recorded after implantation of a subcutaneous implantable cardiac defibrillator (S-ICD). This report describes the efficacy of S-ICDs in a child with an ER pattern after aborted sudden cardiac death.

Successful Percutaneous Thrombectomy of the Left Pulmonary Artery in a Neonate After a Patent Ductus Arteriosus Clipping.

We report a neonate with a successful percutaneous thrombectomy of a total thrombotic occlusion of the left pulmonary artery (LPA) after a surgical clipping for a patent ductus arteriosus (PDA). We suspected the compression of the LPA by the clipping and postoperative hemodynamic instability caused the LPA obstruction. After the surgical removal of the PDA clip and division of the PDA, we could safely retrieve the LPA thrombus with a non-hydrodynamic thrombectomy catheter for coronary arteries.

Association between falling direction and age in older patients with hip fractures.

BACKGROUND: The incidence of fall-related hip fractures in old patients aged over 85 years was reported to be higher than that in old patients aged between 65 and 84 years; however, there are no known studies that reported differences of these age groups with respect to the falling situation. OBJECTIVE: This study investigated the association between age and falling direction in patients with hip fractures. MATERIAL AND METHODS: This study analyzed the medical records of older patients with fall-related hip fractures who were hospitalized in 2011-2018. Demographic (sex, age, and body mass index, BMI), medical and clinical (body mineral density, type of fracture, and cognitive function), and lifestyle variables (use of assistive device for locomotion and place of residence) and characteristics of falling (direction and location) were extracted. These were compared between the patients aged between 65 and 84 years (65-84 group) and over 85 years (85+ group). Multivariable logistic regression analysis was conducted to investigate associations with each falling direction (forward, sideways, and backward) with other variables. RESULTS: Compared with the 65-84 group, the proportion of hip fractures due to sideways falls was lower in the 85+ group (P < 0.05) while the proportion of hip fractures due to backward falls was higher in the 85+ group. The multivariable logistic regression analysis showed the sideways and backward falling were only associated with the age group. CONCLUSION: These results suggested that the falling direction was associated with age but not with other variables investigated in this study in older patients with hip fractures.

Early assessment of cardiac troponin I predicts the postoperative cardiac status and clinical course after congenital heart disease surgery.

Cardiac troponin I (cTnI) is a regulatory protein with a high sensitivity and specificity for cardiac injury. Preoperative and postoperative elevations of cTnI are usually considered predictors of the mortality and morbidity. However, little is known about the relationship between the cTnI and postoperative course after the congenital heart disease (CHD) operation. Sixty-five consecutive patients who underwent cardiac surgery for CHD at our institution between March 2016 and January 2017 were included. The cTnI was measured after the operation. Also, the association between the cTnI and duration of the catecholamine use, ICU stay, aortic cross clamp time, and other clinical parameters were assessed. The cTnI level on postoperative day 1 was positively correlated with the duration of the catecholamine use (p < 0.001) and ICU stay (p < 0.001). Also, a higher cTnI level was associated with a lower urine volume and higher lactate level 24 h after the ICU admission. In the multivariable regression analysis, the cTnI was a significant independent predictor of the catecholamine use (p = 0.002) and ICU stay (p = 0.003). The cTnI level on postoperative day 1 was a predictor of the duration of the catecholamine use and ICU stay.

Comparison of transcatheter patent ductus arteriosus closure between children and adults.

The data comparing the characteristics and effect of transcatheter patent ductus arteriosus (PDA) closure between children and adults is scarce. We analyzed 54 consecutive patients who underwent transcatheter PDA closures. We divided the patients into 2 groups of < 18 years and ≥ 18 years and compared the hemodynamic changes before and after the PDA closure. Adults had a higher incidence of heart failure on admission, diagnoses by heart failure and incidental echocardiography, PDA calcifications, and procedural complications than children (all P < 0.05). The left ventricular end-diastolic volume index (LVEDVI), left atrial diameter index (LADI), and LV mass index (LVMI) decreased after the PDA closure in children but not in adults. The LV ejection fraction (LVEF) significantly decreased 1 day after the PDA closure in both groups but remained low at 6 months after the procedure in only adults. The percent change in the LVEDVI, LADI, LVMI, and LVEF from baseline to 6 months after the procedure was significantly lesser in adults than children (LVEDVI: - 5.2 ± 29.1% vs. - 34.9 ± 18.9%, LADI: - 7.0 ± 13.2% vs. - 22.1 ± 18.9%, LVMI: - 11.0 ± 16.5% vs. - 34.1 ± 15.7%, LVEF: - 5.9 ± 7.6% vs. 6.1 ± 9.1%, all P < 0.05). Transcatheter PDA closure was not associated with a reduction in the LV and LA volume as well as an improvement in the LV hypertrophy and LV function in adults as compared to children. We suggested that an early diagnosis and transcatheter PDA closure during childhood might provide clinical benefit before progressive LV remodeling and heart failure.

Successful Ablation of Atrial Tachycardia Originating from Inside the Single Atrium and Conduit After a Fontan Operation.

An 18-year-old male who had a past medical history of an intracardiac total cavopulmonary connection (TCPC) operation was referred to our hospital for radiofrequency catheter ablation (RFCA) of supraventricular tachycardia (SVT). Two types of SVTs were induced, and 3-dimensional (3D) maps were created using an ultra-high-density 3-dimensional mapping system (Rhythmia). The earliest atrial activation site (EAAS) of SVT1 was at the superior part of the conduit, and the EAAS of SVT2 was at the inferior part of the single atrium (SA). The SVTs were terminated by energy deliveries to the EAAS from the conduit in SVT1 and from inside the single atrium in SVT2. Detailed maps of the SVTs were important to understand the mechanisms of the SVTs. The Rhythmia system was useful for the detailed mapping of complex arrhythmias. The use of Rhythmia in patients after a TCPC is difficult, because puncturing the TCPC conduit and proceeding and manipulating the Orion catheter via a narrow puncture hole are difficult. We were the first to succeed in ablating two atrial tachycardias (ATs) originating from the inside and outside of the conduit after a TCPC operation by using an ultra-high-density 3-dimensional mapping system.

Usefulness of Red Blood Cell Distribution Width in the Assessment of Hemodynamics After Tetralogy of Fallot Repair.

BACKGROUND: There are no reports on the effect of red blood cell distribution width (RDW) in surgical repair of tetralogy of Fallot (ToF). Methods and Results: A total of 50 patients who underwent cardiac catheterization after surgical repair of ToF were retrospectively assessed. RDW was positively correlated with the ratio of right ventricular pressure to left ventricular pressure (RVP/LVP; P<0.0001, r2=0.57). Patients with elevated RDW had a higher RVP/LVP than those with a normal RDW (P<0.0001). Also, elevated RDW was related to elevated central venous pressure (P<0.0001), decreased mixed venous oxygen saturation (P<0.0001), greater pulmonary stenosis (P=0.003) and severe pulmonary regurgitation on echocardiography (P<0.0001), a higher rate of residual ventricular septal defect leak (P=0.004) and higher reoperation rate (P=0.009). Of the 7 patients who underwent reoperation, 6 had decrease in RDW after reoperation (P=0.012). On multivariable regression analysis, RDW was the strongest indicator of higher RVP/LVP. CONCLUSIONS: For the first time, RDW has been shown to be a strong indicator for assessing the hemodynamics and risk of later reoperation after surgical repair of ToF.

Predictors of Early Postoperative Supraventricular Tachyarrhythmias in Children After the Fontan Procedure.

Postoperative arrhythmias are a frequent and fatal complication after the Fontan operation. However, clinical evidence demonstrating early postoperative arrhythmias in children undergoing the Fontan operation is limited. This study aimed to evaluate the prevalence of arrhythmias and identify the predictors of early postoperative supraventricular tachyarrhythmias (SVTs) after the Fontan procedure.Data were analyzed from 80 pediatric patients who underwent Fontan procedures between April 2000 and December 2017 in a single-center retrospective study. Early postoperative SVTs were defined as arrhythmias within 30 days after the Fontan procedure. We divided the patients into two groups, with or without early postoperative arrhythmias, and the predictors of early postoperative arrhythmias were analyzed. A multivariate logistic regression analysis was performed to determine independent predictors of early postoperative SVTs after the Fontan procedure.Early postoperative SVTs were observed in 21 patients (26.3%). The most common arrhythmia was junctional ectopic tachycardia. After an adjustment, an atrioventricular valve regurgitation (AVVR) grade of ≥2 (odds ratio 10.54, 95% confidence interval 2.52 to 44.17, P = 0.001) and preoperative arrhythmias (odds ratio 26.49, 95% confidence interval 1.64 to 428.62, P = 0.021) were significant predictors of early postoperative SVTs after the Fontan operation.An AVVR grade ≥2 and preoperative arrhythmia were significant predictors associated with early postoperative SVTs. Intervention for AVVR may provide clinical benefit for preventing early postoperative arrhythmias after the Fontan operation.