Organic-Inorganic Rare-Earth Double Perovskite Ferroelectric with Large Piezoelectric Response and Ferroelasticity for Flexible Composite Energy Harvesters.

Hybrid organic-inorganic perovskite (HOIP) ferroelectric materials have great potential for developing self-powered electronic transducers owing to their impressive piezoelectric performance, structural tunability and low processing temperatures. Nevertheless, their inherent brittle and low elastic moduli limit their application in electromechanical conversion. Integration of HOIP ferroelectrics and soft polymers is a promising solution. In this work, a hybrid organic-inorganic rare-earth double perovskite ferroelectric, [RM3HQ]2RbPr(NO3)6 (RM3HQ = (R)-N-methyl-3-hydroxylquinuclidinium) is presented, which possesses multiaxial nature, ferroelasticity and satisfactory piezoelectric properties, including piezoelectric charge coefficient (d33) of 102.3 pC N-1 and piezoelectric voltage coefficient (g33) of 680 × 10-3 V m N-1. The piezoelectric generators (PEG) based on composite films of [RM3HQ]2RbPr(NO3)6@polyurethane (PU) can generate an open-circuit voltage (Voc) of 30 V and short-circuit current (Isc) of 18 µA, representing one of the state-of-the-art PEGs to date. This work has promoted the exploration of new HOIP ferroelectrics and their development of applications in electromechanical conversion devices.

Propensity-matched comparison of balloon-expandable and self-expanding valves for transcatheter aortic valve replacement in a Chinese population.

Background: Balloon-expandable valves (BEV) and self-expanding valves (SEV) for transcatheter aortic valve replacement (TAVR) have shown promising results in Western populations. Herein, we comparatively evaluated their hemodynamics and early clinical outcomes in a Chinese population. Methods: One hundred seventy-eight patients with symptomatic aortic stenosis who had undergone transfemoral TAVR using SEV (n=153; Venus-A, 97; VitaFlow, 56) or BEV (n=25; Sapien3) from September 2020 to April 2021 were retrospectively enrolled, and 25 pairs were propensity-score matched for 10 baseline variables. The primary study outcomes were aortic valve hemodynamics and postoperative complications at discharge and 3-month follow-up. Results: TAVR was successful in all patients. Compared with SEV group, the BEV group had similarly distributed baseline characteristics, procedural time, hospital stay, new pacemaker implantation, and paravalvular regurgitation grade. We also observed that the BEV group had lower rates of balloon pre-dilation (60% vs. 92%, P=0.018), post-dilation (0 vs. 20%, P=0.050) and second valve implantation (0 vs. 24%, P=0.022); higher mean transaortic gradient (14.3±6.1 vs. 10.8±4.9, P=0.030) and proportion of patients with elevated gradients (20% vs. 0, P=0.050) at discharge; and similar rehospitalization, mean transaortic gradient, new pacemaker implantation, and paravalvular regurgitation grade than the SEV group at the 3-month follow-up. There were no deaths in either group. However, the proportion of patients with elevated gradients in SEV group was higher at 3 months than before discharge (24% vs. 0, P=0.022). Conclusions: BEV and SEV for transfemoral TAVR appear comparably safe and effective, with high device success and favorable 3-month clinical outcomes. However, the transaortic gradient and new pacemaker implantation in the SEV group increased during follow-up, warranting larger studies with longer-term follow-up.

A novel double-balloon catheter for percutaneous balloon pulmonary valvuloplasty under echocardiographic guidance only.

BACKGROUND: Percutaneous balloon pulmonary valvuloplasty (PBPV) is the procedure of choice for uncomplicated severe or symptomatic pulmonary stenosis. Echocardiography (echo)-guided PBPV can completely avoid the use of radiation and contrast agents compared to fluoroscopy-guided PBPV. Although we have confirmed that echo-guided PBPV is feasible in humans, the poor visibility of the traditional catheter under echo greatly limits the promotion of this new technology. METHODS: We produced a novel double-balloon catheter to make the catheter easy to be detected by echo through adding a guiding balloon at the distal end of the catheter. Echo-guided PBPV was performed on thirty healthy swine using either a novel catheter or a traditional catheter to evaluate the feasibility and safety of the novel double-balloon catheter. The feasibility was evaluated by the success rate of balloon inflation at the pulmonary valve annulus and the operating time. The safety was evaluated by the frequency of balloon slippage and the incidence of complications. RESULTS: There were no significant between-group differences in terms of weight and the ratio of balloon diameter to pulmonary annulus diameter. The success rate was 93.3% and 60% in the novel and traditional groups, respectively. The novel group had significantly (p<0.05) lower mean procedure time (6.33±6.86min vs 24.8±9.79min) and lower frequency of balloon slippage (0.07±0.26 vs 0.53±0.52), arrhythmia (0.07±0.26 vs 0.47±0.52), and tricuspid regurgitation (6.7% vs 40%) than the traditional group. No myocardial hematoma or pericardial tamponade occurred in the novel catheter group. CONCLUSION: Although further studies and improvements are required, the study results indicate that the novel double-balloon catheter for echo-guided PBPV is feasible and safe.

Personalized Three-Dimensional Printing and Echoguided Procedure Facilitate Single Device Closure for Multiple Atrial Septal Defects.

BACKGROUND: To evaluate the feasibility of using a single device to close multiple atrial septal defects (ASDs) under the guidance of transthoracic echocardiography (TTE) and with the aid of three-dimensional (3D) printing models. METHODS: Sixty-two patients with multiple ASDs were retrospectively analyzed. Thirty of these patients underwent TTE-guided closure (3D printing and TTE group) after a simulation of occlusion in 3D printing models. The remaining 32 patients underwent ASD closure under fluoroscopic guidance (conventional group). Closure status was assessed immediately and at 6 months after device closure. RESULTS: Successful transcatheter closure with a single device was achieved in 26 patients in the 3D printing and TTE group and 27 patients in the conventional group. Gender, age [18.8 ± 15.9 (3-51) years in the 3D printing and TTE group; 14.0 ± 11.6 (3-50) years in the conventional group], mean maximum distance between defects, prevalence of 3 atrial defects and large defect distance (defined as distance ≥7 mm), and occluder size used were similarly distributed between groups. However, the 3D printing and TTE group had lower frequency of occluder replacement (3.8% vs 59.3%, p < 0.0001), prevalence of mild residual shunts (defined as <5 mm) immediately (19.2% vs 44.4%, p < 0.05) and at 6 months (7.7% vs 29.6%, p < 0.05) after the procedure, and cost (32960.8 ± 2018.7 CNY vs 41019.9 ± 13758.2 CNY, p < 0.01). CONCLUSION: The combination of the 3D printing technology and ultrasound-guided interventional procedure provides a reliable new therapeutic approach for multiple ASDs, especially for challenging cases with large defect distance.

Multicenter Comparison of Percutaneous and Surgical Pulmonary Valve Replacement in Large RVOT.

BACKGROUND: A percutaneous approach for pulmonary valve replacement (PVR) is a feasible alternative to surgical PVR in selected patients with severe pulmonary regurgitation after repair of tetralogy of Fallot. However, large right ventricular outflow tract (diameter ≥ 25 mm) remains challenging. METHODS: This retrospective multicenter study enrolled consecutive patients with large right ventricular outflow tract who underwent percutaneous PVR (Venus P-valve, Venus MedTech Inc, Hangzhou, China) (n = 35) or surgical PVR (homograft valve; n = 30) between May 2014 and April 2017. Patients were followed up at 1, 3, 6, and 12 months, and yearly thereafter. Main study outcomes were pulmonary valve function and right ventricular function at discharge and midterm follow-up. RESULTS: PVR was successful in all patients. Percutaneous compared with surgical PVR group had: similarly distributed baseline characteristics; shorter hospitalization, intensive care unit stay, and endotracheal intubation duration; lower cost; lower pulmonary valve gradient before discharge; lower pulmonary valve regurgitant grade (mean difference, -0.63; 95% CI -1.11 to -0.20, P = .022), pulmonary valve gradient (mean difference, -5.7 mm Hg; 95% CI -9.4 to -2.2 mm Hg, P = .005), and right ventricular end-diastolic volume index (mean difference, -9.5 mL/m2; 95% CI -16.9 to -3.1 mL/m2, P = .022); and greater right ventricular ejection fraction (mean difference, 5.4%; 95% CI 2.4%-8.3%, P = .002) at median 36 months follow-up, without deaths in either group. CONCLUSIONS: Percutaneous PVR using Venus P-valve appeared to be a safe, efficacious and minimally invasive alternative to surgical PVR in selected patients with large right ventricular outflow tract yielding better right ventricular and pulmonary valve function at midterm follow-up.

Percutaneous closure of patent foramen ovale under transthoracic echocardiography guidance-midterm results.

BACKGROUND: Conventional percutaneous closure of patent foramen ovale (PFO) is usually performed under the guidance of fluoroscopy. Whether closure of PFO under transthoracic echocardiography (TTE) guidance only is safe and effective is unknown. The present study therefore aimed to assess the safety and efficacy of percutaneous closure of PFO under TTE guidance only. METHODS: This study retrospectively enrolled a total of 52 consecutive patients (55.8% male, mean age 34.0±13.0 years, range, 10-59 years) with PFO treated at our institution from June 2015 to September 2017 by percutaneous closure under echocardiographic guidance only. The patients mean body weight was 58.7±10.8 kg. Patients underwent follow-up by TTE immediately post procedure by electrocardiogram and TTE at 1, 3, 6 and 12 months after discharge and annually thereafter, and by clinical evaluation at all time points. RESULTS: Of the 52 patients, 47 (90.4%) were successfully treated by percutaneous closure under TTE guidance. The mean procedure duration (from puncture to sheath removal) was 21.0±6.2 (range, 11-33) minutes. A trivial residual shunt which disappeared 24 hours later was observed in only 1 (1.9%) patient immediately post procedure. Median hospital stay was 3.0 days without severe complications such as peripheral vascular injury or cardiac perforation at discharge. At median 15.5 (11.3, 18.0) months follow-up, there were no complications such as death, stroke, transient ischemic attack (TIA) and residual shunt. CONCLUSIONS: In this single center study of mostly lean patients, percutaneous closure of PFO under TTE guidance as the only imaging tool appeared effective at midterm follow-up, while avoiding radiation exposure, endotracheal intubation and contrast agent use.

A Novel Wire Is Effective for Echo-Guiding Percutaneous Atrial Septal Defect Closure: A Preclinical Study.

Objective: To assess the effectiveness of a novel ultrasound wire for echo-guiding percutaneous atrial septal defect (ASD) closure in a sheep model. Methods: After right lateral thoracotomy, ASDs were created in 20 sheep by transseptal needle puncture followed by balloon dilatation. Animals were evenly randomized into 2 groups to undergo ASD closure using echography as the only imaging tool with either COOK wire (control group) or new ultrasound wire (study group). The total procedural time, passing time (time needed for the guide wire to enter the left atrium), frequency of delivery sheath dropping into the right atrium, frequency of arrhythmias, and 1-week rate of complications were compared between the two groups. Results: All animals survived defect creation procedures uneventfully. ASD devices were successfully implanted in all sheep. Compared with the control group, the study group had significantly (P < 0.05) lower mean procedure time (15.36 ± 4.86 versus 25.82 ± 7.85 min), lower mean passing time (2.69 ± 0.82 versus 5.58 ± 3.34 min), lower frequency of the guide wire dropping into the right atrium (0% versus 40%), and lower frequency of atrial (4.41 ± 2.61 versus 9.60 ± 3.68) or ventricular premature contractions (0.75 ± 0.36 versus 1.34 ± 0.68), respectively, without serious complications up to one week. Conclusion: The novel ultrasound specialized guide wire was effective in echo-guiding percutaneous ASD closure.

Hybrid Balloon Valvuloplasty for the Treatment of Severe Congenital Aortic Valve Stenosis in Infants.

BACKGROUND: Surgical or percutaneous interventional treatment of severe congenital aortic valve stenosis (CAS) in early infancy remains challenging. This single-center, retrospective study analyzed midterm outcomes of a hybrid balloon valvuloplasty procedure through the ascending aorta by way of median sternotomy, including cases with improved technique. METHODS: Included were 45 consecutive infants (aged <90 days) with CAS and selected for biventricular repair who underwent hybrid balloon valvuloplasty in a hybrid or ordinary operating room from October 2010 to March 2016. Patients were assessed at 1, 3, 6, and 12 months and yearly thereafter. RESULTS: Hybrid balloon valvuloplasty was successful in all patients, with the last 8 treated in an ordinary operating room under only echocardiography guidance with a new sheath. Thirty-two patients were successfully rescued from low heart rate or left ventricular systolic dysfunction, or both, by cardiac massage under direct visualization; none required cardiopulmonary bypass. The degree of new aortic insufficiency was mild in 7 patients and changed from mild to moderate in 1 patient. Aortic valve pressure gradient decreased from 70.6 ± 17.5 mm Hg preoperatively to 15.2 ± 4.2 mm Hg immediately postoperatively (p < 0.001). Fluoroscopy time was 4.8 ± 2.3 minutes. At a median of 32.1 months (range, 1 to 68 months) follow-up, all patients were alive and healthy. Aortic valve pressure gradient remained low (19.1 ± 5.2 mm Hg). Left ventricular ejection fraction increased from 0.515 ± 0.134 (range, 0.21 to 0.70) preoperatively to 0.633 ± 0.035 (range, 0.58 to 0.75; p < 0.001). No aortic insufficiency developed, and no patient required reintervention. CONCLUSIONS: For infants with severe CAS, hybrid balloon valvuloplasty through the ascending aorta by way of a median sternotomy appears efficacious and safe up to midterm follow-up.

Perventricular device closure of perimembranous ventricular septal defect: effectiveness of symmetric and asymmetric occluders.

Objectives: To assess safety and effectiveness of symmetric and asymmetric occluders in perventricular device closure without cardiopulmonary bypass of perimembranous ventricular septal defects (pmVSDs). Methods: The present retrospective study enrolled 581 patients who underwent perventricular device closure of pmVSDs under transoesophageal echocardiography guidance from May 2011 to April 2016, and outpatient electrocardiography and transthoracic echocardiography assessments at 1, 3, 6 and 12 months, and yearly thereafter. Results: The overall success rate of device implantation was 92.6% (43 surgical conversions immediately). Between patients receiving symmetric ( n = 353) and asymmetric ( n = 185) occluders, there were no significant differences in age, weight and defect diameter distributions; however, both before discharge and at mean 28.6 ± 21.2 (range, 1-60)-month follow-up, the symmetric group had lower rates of trivial residual shunt (5.7% vs 11.4%, P = 0.018; and 0.8% vs 5.9%, P = 0.001) and bundle branch block (0.8% vs 5.4%, P = 0.002; and 0.6% vs 3.8%, P = 0.009); and at follow-up, the asymmetric group had lower residual shunt (47.6% vs 85.0%, P = 0.020) and similar branch block (30.0% vs 33.3%, P = 1.000) disappearance rates. There were no severe complications, i.e. aortic regurgitation, malignant arrhythmias, haemolysis or device dislocation. Conclusions: Perventricular device closure of pmVSDs appears safe and effective with symmetric and asymmetric occluders. However, the lower residual shunt disappearance and higher branch block incidence rates for asymmetric occluders would favour more proactive conversion to surgical repair immediately when residual shunt is present intraoperatively.

First-in-Human Percutaneous Balloon Pulmonary Valvuloplasty Under Echocardiographic Guidance Only.

OBJECTIVE: The objective of this study was to assess the feasibility of percutaneous balloon pulmonary valvuloplasty (PBPV) under echocardiographic guidance only. SETTING: PBPV has become the preferred choice for pulmonary valve stenosis (PS). We report the first-in-human successful PBPV under only echocardiography guidance for isolated PS. METHODS: From March 2013 to December 2014, 34 patients with congenital PS underwent PBPV with echocardiography as the only imaging modality in the ordinary operation room or catheter lab. Outpatient follow-up including chest radiography, electrocardiography, and transthoracic echocardiography (TTE) was conducted at 1, 3, 6, and 12 months. RESULTS: All 34 patients successfully underwent PBPV under echocardiography guidance without radiation and contrast agent. The pulmonic transvalvular pressure gradient dropped from 62.8 ± 10.1 mm Hg to 14.7 ± 4.2 mm Hg measured on catheterization (P < .05). The balloon diameter/pulmonary annulus diameter ratio was 1.34 ± 0.07. Slight regurgitation of the pulmonary valve occurred in five patients and mild pulmonary regurgitation occurred in one patients. The pulmonic transvalvular pressure gradient measured on TTE 12 months after the procedure was 14.1 ± 4.6 mm Hg. No pericardial effusion and peripheral vascular complications occurred. CONCLUSION: This study demonstrated that PBPV can be successfully performed under only echocardiography guidance and appears safe and effective while avoiding radiation and contrast agent use.

Transthoracic Echocardiography-Guided Percutaneous Patent Ductus Arteriosus Occlusion: A New Strategy for Interventional Treatment.

INTRODUCTION: Percutaneous patent ductus arteriosus (PDA) occlusion has become the preferred therapeutic option, which uses fluoroscopy as the guidance. To reduce the x-ray exposure, PDA occlusion using the Amplatzer Duct Occluder II (ADO II) under guidance of transthoracic echocardiography only was conducted. This single center study aims to access the safety and efficiency of this new strategy. METHODS AND RESULTS: From June 2013 to May 2015, 63 consecutive PDA patients underwent transthoracic echocardiography-guided PDA occlusion through the femoral artery. Outpatient follow-up was conducted at 1, 3, and 6 months, and yearly. Sixty-two patients successfully underwent echocardiography-guided percutaneous PDA occlusion. One patient was converted to minimally invasive transthoracic occlusion due to failure of delivery sheath passage through tortuous PDA. Mean procedure duration was 24.3 ± 7.0 minutes; ADO II diameter averaged 4.6 ± 0.9 mm; 8 cases showed traces of residual shunt immediately after operation which resolved after 24 hours; and mean hospital stay was 3.4 ± 0.5 days. There was no occluder migration, hemolysis, pericardial effusion, pulmonary branch or aortic stenosis at mean 13.5 ± 4.8 months follow-up. CONCLUSIONS: This study demonstrated that percutaneous PDA occlusion can be successfully performed under guidance of transthoracic echocardiography only and appears safe and effective while avoiding radiation and contrast agent use.

Percutaneous Closure of Atrial Septal Defects Under Transthoracic Echocardiography Guidance Without Fluoroscopy or Intubation in Children.

OBJECTIVE: Demonstrate the benefits of percutaneous atrial septal defect (ASD) closure under guidance of transthoracic echocardiography (TTE) without fluoroscopy. METHODS: From February 2013 to April 2014, 127 consecutive patients with an isolated type II ASD were recruited to undergo percutaneous closure under either TTE (n = 60, TTE group) or TEE (n = 67, TEE group) guidance. The TTE group received local anesthesia or sedation with propofol, and the TEE group received general anesthesia with endotracheal intubation. Follow-up examinations were performed for both groups at 1 month, 3 months, 6 months, and 1 year after discharge and annually thereafter. RESULTS: The TTE group had a significantly shorter procedure time and respirator ventilation duration than the TEE group. The dose of propofol required, the cost, and the pharyngeal complication rate were significantly lower in the TTE group than in the TEE group. The median follow-up of 11.6 months was uneventful in all patients. CONCLUSIONS: Percutaneous ASD closure with TTE guidance as the only imaging tool avoids fluoroscopy, endotracheal intubation, and probe insertion and is associated with a satisfactory procedural success rate and lower costs. This procedure is a safe and reliable treatment for ASD.

Hybrid balloon valvuloplasty through the ascending aorta via median sternotomy in infants with severe congenital valvular aortic stenosis: feasibility of a new method†.

OBJECTIVES: To evaluate a novel hybrid balloon valvuloplasty procedure for severe congenital valvular aortic stenosis in low-weight infants, performed through the ascending aorta via median sternotomy. METHODS: Eighteen infants (<90 days of age) with severe congenital aortic stenosis were included in this study. Hybrid balloon valvuloplasty procedures were performed in a hybrid operating room. Patients were followed up at 3 months, 6 months, 1 year and then annually following the procedure. RESULTS: The hybrid balloon valvuloplasty procedure was successful in all patients. Eight patients were successfully rescued from left ventricular systolic dysfunction by cardiac compression under direct vision. The aortic valve pressure gradient decreased from 80.3 ± 20.8 mmHg preoperatively to 16.0 ± 3.6 mmHg immediately postoperatively (P < 0.001). None of the patients developed significant aortic insufficiency. The fluoroscopy time was 6.2 ± 2.9 min. Intraoperative blood transfusions and pacing were not required. The patients were all alive and healthy at the end of the follow-up period (mean 21.3 months; range 3-41 months), and the aortic valve pressure gradient remained low (21.7 ± 5.3 mmHg). Reintervention was not required in any of the patients. CONCLUSIONS: Hybrid balloon valvuloplasty through the ascending aorta via median sternotomy is an effective and safe procedure for infants with severe congenital aortic stenosis.

[Safety and efficacy of percutaneous transcatheter closure of atrial septal defect under transesophageal echocardiography guidance in children].

OBJECTIVE: To assess the safety and effectiveness of percutaneous transcatheter closure of atrial septal defect (ASD) under transesophageal echocardiography (TEE) guidance in children. METHODS: The study included 20 cases of patients with ASD. The patients were (4.2 ± 1.2) years old and the mean body weights were (18.2 ± 4.2) kg. The diameter of ASD before closure was (13.4 ± 3.3) mm . All procedures were guided under TEE. Procedure success was evaluated by TEE immediately after procedure. RESULTS: Closure devices were successfully implanted in all 20 patients under TEE guidance. The diameter of closure devices was 14-26 mm. There were no procedure related complications. The ventilation time was (2.9 ± 0.8)h and the hospitalization time was (3.2 ± 0.7) days. CONCLUSION: TEE guided percutaneous transcatheter closure is safe and effective for patients with ASD and avoids the radiation damages.

[A modified Calgary syncope syndrome score in the differential diagnosis between cardiac syncope and vasovagal syncope].

OBJECTIVE: This study aimed at analyzing the usefulness of a modified Calgary Syncope Syndrome Score in the differential diagnosis between cardiac syncope (CS) and vasovagal syncope (VVS) in children through a large sample clinical study. METHOD: Totally 189 children [112 males, 77 females, aged 2 - 18 yrs, mean age (12.4 ± 3.1) yrs] with CS and VVS who were at the syncope clinic or admitted to the Department of Pediatrics, Peking University First Hospital from August 2002 to April 2011 were included in the study. The diagnosis was analyzed by a modified Calgary Syncope Syndrome Score and receiver operating characteristic (ROC) curve was used to explore the predictive value of different Calgary Syncope Syndrome Scores in differential diagnosis between CS and VVS. RESULT: There were significant differences in the score between CS [-5.00(-7, 1)] and VVS [1(-4, 6)] (P < 0.01). When the score was ≤ -2.5, the sensitivity and specificity of the differential diagnosis between CS and VVS were 95.4% and 67.7%, respectively. Since the modified Calgary Syncope Syndrome Score was integer number, CS should be considered when the score was less than -3. CONCLUSION: The modified Calgary Syncope Syndrome Score might be used as an initial diagnostic method in differential diagnosis between CS and VVS, based on the history of the patients.

A diagnosis-based health economic analysis of postural orthostatic tachycardia syndrome in Chinese children.

BACKGROUND: Postural orthostatic tachycardia syndrome (POTS) is a common clinical problem in children and adolescents. The previous diagnostic approach to POTS of children and adolescents is based on a series of tests to exclude all other causes, which is time and medical resource consuming. Recently, a new diagnostic approach has been developed. The present study was designed to statistically analyze the results of clinical investigation items and the cost for the diagnosis of POTS in children patients, and evaluate cost changes in the diagnosis of POTS. METHODS: A total of 315 children patients were divided into two groups according to diagnosis period, including group I diagnosed in 2002 - 2006 (100 cases) and group II in 2007 - 2010 (215 cases) and the diagnostic item-based distribution of the cost was analyzed. The diagnostic costs were compared between two groups using SPSS17.0. RESULTS: The per-capita cost of diagnosis in group I was (621.95 ± 21.10) Yuan, costs of diagnostic tests (head-up tilt test, standing test, etc) accounted for 8.68% and the exclusive tests for 91.32%. The per-capita cost of diagnosis in group II was (542.69 ± 23.14) Yuan, diagnostic tests accounted for 10.50% and exclusive tests for 89.50%. Comparison of the total cost of diagnostic tests between the two groups showed significant differences (P < 0.05). CONCLUSION: The cost of POTS diagnosis has been declined in recent years, but the cost of exclusive diagnosis is still its major part.

[Therapies for postural tachycardia syndrome in children].

OBJECTIVE: This study was designed to compare the short-term and long-term effects of oral rehydration salts, oral rehydration salts plus metoprolol or oral rehydration salts plus midodrine hydrochloride on the treatment of postural tachycardia syndrome (POTS) in children. METHOD: A total of 118 children with POTS were divided into oral rehydration salts group (n = 39), metoprolol group (oral rehydration salts plus metoprolol, n = 10) or midodrine hydrochloride group (oral rehydration salts plus midodrine hydrochloride, n = 69). The patients were followed up in clinics or over telephone for 3 - 18 months, with a mean of (11.7 ± 4.1) months. The symptom scores were recorded before treatment, after 3 months and at the end of the follow-up. Reduction of the score by 2 points or more was considered that the treatment was effective. The effective rate in 3 months was applied to evaluate short-term effects of 3 different therapies by chi-square test. Taking futility as events, Kaplan-Meier curves were drawn to compare long-term effects of the 3 different therapies in treating POTS in children. RESULT: No significant differences among the 3 groups were found in sex, age, body height, weight, the symptom scores before treatment or hemodynamic variables. Oral rehydration salts, metoprolol and midodrine hydrochloride improved clinical symptoms after 3 months. The symptom scores of the 3 groups before treatment and after 3 months were 2.4 ± 3.2 vs. 5.5 ± 2.9, 2.2 ± 3.0 vs. 6.1 ± 3.0 and 1.9 ± 1.6 vs. 5.9 ± 2.7, respectively. The difference was significant (P < 0.05). Descending order of the short-term effective rate was 91.3% in midodrine hydrochloride group, 80.0% in metoprolol group and 74.4% in oral rehydration salts group. The difference was significant (χ(2) = 5.85, P < 0.05). All the 3 different therapies improved clinical symptoms at the end of follow-up. The symptom scores were 2.6 ± 3.2 vs. 5.6 ± 2.9, 2.5 ± 3.1 vs. 6.1 ± 3.0 and 2.2 ± 2.1 vs. 6.0 ± 2.7, respectively. (P < 0.05). The result of the Kaplan-Meier curves showed that the long-term effect of midodrine hydrochloride was significantly superior to metoprolol group and oral rehydration salts group (P < 0.05). There was no significant difference between the latter two groups. CONCLUSION: Oral rehydration salts plus midodrine hydrochloride or plus metoprolol improved the efficacy of drugs in children with POTS. And the efficacy of midodrine hydrochloride was superior to that of metoprolol.

[Endogenous formaldehyde and cardiovascular diseases].

Endogenous formaldehyde is produced via semicarbazide-sensitive amine oxidase-catalyzed deamination of methylamine. It widely exists in a variety of tissues and cells in animals. It has been confirmed that endogenous formaldehyde is involved in the neural degeneration, immune disease and tumor process. Adipocytes, vascular endothelial cells and smooth muscle cells are rich in enzyme to generate formaldehyde-semicarbazide-sensitive amine oxidase (SSAO). Formaldehyde may cause cytotoxicity, which induces vascular endothelial injury and mediates multiple factor-induced pathogenic process of vascular injury. It plays important role in atherosclerosis, diabetes mellitus and diabetic complication.

Enhancing Penicillin G Acylase Stability by Site-directed Mutagenesis.

To improve the stability of penicillin G acylase(PGA) from Bacillus megaterium, a three-dimensional model of B.megaterium PGA was constructed based on crystal structure of penicillin G acylase from E.coli using PMODELING program. The mutation of Lys at beta427 and 430 to Ala was predicted to enhance the stability of PGA in acidic or organic solvent environment. The results showed that 2 mutant PGA had similar specific activity and Km as the parent PGA. Their optimum pH dropped 0.5 pH units. The stability of Lys430Ala was enhanced obviously at pH 5.2. The half lives of Lys427Ala and Lys430Ala were improved by 60 % and 166 %, respectively, in comparison with the parent PGA.