Simple TGA Research Articles

Urgent neonatal balloon atrial septostomy in simple transposition of the great arteries: predictive value of fetal cardiac parameters

To investigate the impact of abnormal perinatal loading conditions on cardiac geometry and function in term fetuses and neonates with transposition of the great arteries with intact interventricular septum (simple TGA), and to explore the predictive value of fetal cardiac parameters for an urgent balloon atrial septostomy (BAS) after birth. This was a prospective longitudinal follow-up study of women delivering at term, including both uncomplicated pregnancies with normal outcome and pregnancies affected by fetal simple TGA. Conventional, spectral-tissue Doppler and speckle-tracking echocardiographic parameters were obtained within 1 week before delivery and within the first few hours after delivery. Neonates with simple TGA that required urgent BAS were assessed after the procedure and before corrective arterial switch surgery. Cardiac parameters were normalized by cardiac cycle length, ventricular end-diastolic length or end-diastolic dimension, as appropriate. Fetal and neonatal cardiac parameters were compared between simple-TGA cases and controls, and perinatal changes in the simple-TGA group were assessed. Receiver-operating-characteristics (ROC)-curve analysis was used to assess the predictive value of fetal cardiac parameters for urgent BAS after birth in the simple-TGA group. A total of 67 pregnant women delivering at term were included in the study (54 normal pregnancies and 13 with a diagnosis of fetal simple TGA). Compared with normal term fetuses, term fetuses with simple TGA exhibited more globular hypertrophied ventricles, increased biventricular systolic function and diastolic dysfunction (right ventricular (RV) sphericity index (SI), 0.58 vs 0.54; left ventricular (LV)-SI, 0.55 vs 0.49; combined cardiac output (CCO), 483 vs 406 mL/min/kg; LV torsion, 4.3 vs 3.0 deg/cm; RV isovolumetric relaxation time (IVRT'), 127 vs 102 ms; P < 0.01 for all). Compared with normal neonates, neonates with simple TGA demonstrated biventricular hypertrophy, a more spherical right ventricle and altered systolic and diastolic functional parameters (RV-SI, 0.61 vs 0.43; RV myocardial performance index, 0.47 vs 0.34; CCO, 697 vs 486 mL/min/kg; LV-IVRT', 100 vs 79 ms; RV-IVRT', 106 vs 71 ms; P < 0.001 for all). Paired comparison of neonatal and fetal cardiac indices in the simple-TGA group showed persistence of the fetal phenotype, increased biventricular systolic myocardial contractility and CCO, and diastolic dysfunction (RV systolic myocardial velocity (S'), 0.31 vs 0.24 cm/s; LV-S', 0.23 vs 0.18 cm/s; CCO, 697 vs 483 mL/min/kg; LV torsion, 1.1 vs 4.3 deg/cm; P < 0.001 for all). Several fetal cardiac parameters in term fetuses with simple TGA demonstrated high predictive value for an urgent BAS procedure after birth. Our proposed novel fetal cardiac index, LV rotation-to-shortening ratio, as a potential marker of subendocardial dysfunction, for a cut-off value of ≥ 0.23, had an area under the ROC curve (AUC) of 0.94, sensitivity of 100% and specificity of 83%. For RV/LV end-diastolic area ratio ≥ 1.33, pulmonary-valve-to-aortic-valve-dimension ratio ≤ 0.89, RV/LV cardiac output ratio ≥ 1.38 and foramen-ovale-dimension-to-total-interatrial-septal-length ratio ≤ 0.27, AUC was 0.93-0.98, sensitivity was 86% and specificity was 83-100% for all. Simple-TGA fetuses exhibited cardiac remodeling at term with more profound alterations in these cardiac parameters after birth, suggestive of adaptation to abnormal loading conditions and possible adaptive responses to hypoxemia. Perinatal adaptation in simple TGA might reflect persistence of the abnormal parallel arrangement of cardiovascular circulation and the presence of widely patent fetal shunts imposing volume load on the neonatal heart. The fetal cardiac parameters that showed high predictive value for urgent BAS after birth might reflect the impact of late-gestation pathophysiology and progressive hypoxemia on fetal cardiac geometry and function in simple TGA. If these findings are validated in larger prospective studies, detailed cardiac assessment of fetuses with simple TGA near term could facilitate improvements in perinatal management and refinement of the timing of postnatal intervention strategies to prevent adverse pregnancy outcomes. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

A 3-Year Single Surgeon Experience of the Arterial Switch Operation

Background: The arterial switch operation [ASO] is the surgical procedure of choice for correction of the TGA. This is one of the most complex cardiac surgeries, with coronary artery transfer being the most important factor determining the success of the surgery. Objectives: This study aims to investigate the outcomes of ASO operated by a single surgeon and assess the accuracy of echocardiography in identifying the coronary artery pattern before the ASO, this may lead to a better familiarization with the ASO. Methods: A retrospective study was conducted by operative and postoperative case note review of 125 patients from March 2015 to 2018. We assessed the outcomes of the arterial switch operation. Concomitant defects as atrial septal defects, patent ductus arteriosus and small ventricular septal defects were defined as the simple TGA and other defects were defined as the complex TGA. Coronary artery pattern determination by echocardiography prior to the surgery and during the operation was investigated, as well. 30-day mortality, post-operative neurologic complications, cardiac anatomic complications, arrhythmia, plasma lactate level and cardiopulmonary bypass time [CPB time] during the surgery were recorded. Results: The mean age and weight of the patients were 29.09 (1 - 180) days and 3506.48 (2400 - 9700) grams. Most of the patients (64%) were male. 105 (84%) of the patients had simple and 20 (16%) had complex TGA. Unusual coronary pattern during echocardiography was observed in 17 (13.6%) subjects and unusual coronary pattern during the operation was observed in 7 (5.6%) patients. The incidence of the major anatomical lesions was not significant. 20 (16%) had neurologic complications, including seizure in 14 (11.2%) patients, brain hemorrhage was found in 5 (4%) patients, as well as chorea and wrist drop in the remaining patients. Post-operative arrhythmia was observed in 16 (12.8%) patients. The mortality rate was 4% (5 patients). The CPB time was 202.73 ± 36.99 minutes. Conclusions: Our post-operative results of the ASO indicate excellent results. This signifies high experience and knowledge regarding this surgery.

Amending the thermo-mechanical response and mechanical properties of epoxy composites with silanized chopped carbon fibers

This study demonstrates the ability of functionalized chopped carbon fibers (CCFs) chosen from industrial waste to improve the thermo-mechanical properties of CCFs/epoxy composites. The defect sites onto the CCFs were created by their oxidation and the oxidized CCFs were covalently linked with siloxane functional groups to conceal their defects. The surface functionalization of CCFs was characterized by a simple chemical route, FTIR and TGA analysis, respectively. The surface morphology of functionalized CCFs showed the generation of highly dense networked globules. Epoxy composites filled with 0.5wt% of siloxane attached CCFs (S-CCFs) showed a tremendous enhancement in storage modulus (∼376%) without sacrificing their thermal stability. Furthermore, the S-CCFs reinforced epoxy composites demonstrate a significant improvement in the tensile and fracture properties. Such enhancement in the mechanical properties can open up the scope for the utilization of CCFs as a potential cost-effective candidate for high-performance next generation structural composites.

292: Pulmonary arterial hypertension complicating arterial switch surgery for simple transposition of the great arteries-prevalence and outcomes

Pulmonary arterial hypertension after successful arterial switch operation (ASO) for simple transposition of the great arteries is a rare but important cause of late morbidity and mortality. However this complication is poorly characterised in the literature. In Here, we report the prevalence of this condition and its outcomes from the largest series of ASO procedures yet reported. Between January 1985 and June 2011, 1137 arterial switch procedures were performed for simple TGA at the Hôpital Necker Enfants Malades in Paris. All patients underwent ASO within the early neonatal period. In all cases, pulmonary pressure was evaluated at routine echocardiography and pulmonary hypertension was confirmed by right heart catheterisation. Of 1137 consecutive ASO cases, 8 patients (0.7%, 95% confidence interval 0.29-1.36%) developed severe PAH in the peri-operative period that persisted beyond 1 month post-operatively requiring PAH targeted therapy. Three of those resolved with treatment after 3, 4 and 5 months respectively. The prevalence of PAH in a general French paediatric population was estimated to be 3.7 per million. These data suggest that long-term survivors of the ASO have a relative risk for the development of PAH around 2000-fold (point estimate 1757-fold, 95% confidence interval 785-3932) compared to children without congenital heart disease. Pulmonary hypertension is a severe complication of TGA which must be rapidly detected in order to initiate targeted therapy. Reversibility is indeed not excluded since last cases of our series have normalized their pulmonary pressure.

Senning operation for correction of the transposition of the great arteries, results, long-term outcome and quality of life

Objective: Long-term results after the Senning operation for transposition of the great arteries are little known. Sinus node dysfunction and systemic ventricular dysfunction are crucial in patient survival. We evaluated the results, long term outcome and quality of life in a group of 39 patients. Methods: The study was a retrospective analysis, of 39 (39/40 = 97.5%) surgical surviving patients, submitted to Senning operation, with a mean follow-up time of 14.7 +/– 3.1 years. Electrocardiogram, echocardiogram, and chest radiograph series were performed every 6 months. Thirty six patients of this series underwent Holter study and ergometric test, to evaluate the physical capacity. Three patients living overseas were excluded. Results: There was only one late death (1/39) (late mortality = 2.5%): a 16 year-old patient had a no cardiac death. The actuarial survival was 95.0% (38/40) (simple or with little VSD, TGA). The probability of staying in sinus rhythm, in 39 surviving patients was 77.1% (30) or normal right ventricular function was 76.5% (29), 10 to 20 years after operation. The incidence of sinus node and right ventricular dysfunction increased gradually over time. No re-operations and pacemaker implantation, was performed. Functional class: I = 30 (85.7%) cases and functional class II = 5 (14.3%) cases. Conclusions: Patients with simple TGA submitted to Senning procedure in our experience, presented during late follow-up: 1—Low incidence of right ventricular dysfunction and active arrhythmias; 2—Low mortality and no sudden death recorded; 3—Good quality of life and 4—Satisfactory surgical results (free of re-operation or definitive pacemaker implantation).

Elucidating the LiFePO4 air aging mechanism to predict its electrochemical performance

Although LiFePO4-based chemistry has been extensively studied and developed in the last decade due to its promise for the next generation of Li-ion battery applications, the impact of ambient air exposure and the concomitant aging mechanism is still a controversial matter. In the present study, we describe quantitatively the aging process in terms of the successive phase formation, distribution and iron local environments. Formation and growth of a disordered ferric phosphate phase are directly observed for the first time from the surface of particles toward the core, preceding the crystallization of tavorite LiFePO4(OH) as observed through the combination of amorphous phase quantification by XRD, and by Mossbauer and Electron Energy Loss spectroscopies. Structural and electrochemical characterization prove that the amorphous ferric phosphate formed in the early aging stage exhibits already tavorite composition and structure at the local scale and shed light on a crucial step of the aging mechanism. Based on the correlation we establish here between the amounts of Fe(III) and hydroxyls groups present in aged samples and specific capacity of the corresponding electrodes, we show that the degradation of active material upon storage and the electrochemical performance can be predicted easily through simple TGA measurements.

Invited commentary

The current report from the Cleveland Clinic Group on 117 arterial switch operations, including patients with simple and complex TGA or DORV, describes a mortality of less than 1%. This level of excellence may remain unchallenged for a long time.

Outcomes of 829 neonates with complete transposition of the great arteries 12-17 years after repair.

Between 1985 and 1989, the surgical management of neonates with complete transposition (TGA) underwent a transition from atrial to arterial repair. We sought to examine the intermediate outcomes and their associated risk factors in neonates repaired during the era of transition. Twenty-four institutions entered 829 neonates age less than 15 days in a prospective study. Diagnosis was simple TGA (n=631), TGA with ventricular septal defect (VSD) (n=167), TGA with VSD and pulmonary stenosis (TGA/VSD/PS) (n=30), or TGA with PS (n=1). Repair was by arterial switch (n=516), atrial repair (Senning=175, Mustard=110) or Rastelli (n=28). Time-related events were analysed by parametric hazard function modeling and incremental risk factors for mortality, re-intervention, and late functional assessment were sought. Survival estimates at 6 months, 5, 10, and 15 years are 85, 83, 83, and 81%, respectively. The hazard function for death after repair has two phases: an early rapidly declining phase and an ongoing constant one. Constant phase mortality is less likely after the arterial switch operation and in children with simple TGA. During follow up, at least one re-intervention was required in 167 children (pacemaker, n=35; percutaneous intervention, n=32; baffle re-intervention, n=27; re-operation, n=125). Freedom from re-intervention at 6 months, 5, 10 and 15 years is 93, 82, 77, and 76%, respectively. Of survivors, 87% have been followed up to the last 3 years, including an assessment of functional ability of 562 children (83%). Functional class 15 years after repair is class I in 76%, II in 22%, III in 2%. The proportion in functional class I decreased over time. Psychosocial deficits, especially learning disorders are prevalent. Survival 15 years after TGA repair is good with most children functioning well, and results are best after an arterial switch operation. There is an ongoing risk of death that is less after the arterial switch operation. With the exception of Rastelli patients, the likelihood of survivors needing re-intervention after 5 years is low. There is need for improved neurodevelopmental outcomes.

Complete transposition of the great arteries: surgical concepts for patients with systemic right ventricular failure following intraatrial repair.

One of the most serious late complications of the intraatrial baffle procedure (Mustard or Senning correction) in patients suffering from transposition of the great arteries, (TGA) is the late systemic right ventricular failure. Nearly all patients presenting with right ventricular dysfunction have severe associated tricuspid regurgitation. The surgical options for these patients include tricuspid valve reconstruction or replacement, staged conversion to the arterial switch operation and orthotopic heart transplantation. Review of 189 operative survivors who underwent the Mustard or Senning operation for TGA between 1970 and 1993 in our institution revealed 12 patients (6.3%) who died from severe systemic right ventricular dysfunction (mean follow-up 16+/-3.5 years), which was the most common cause of late death. All of them had concomitant severe tricuspid regurgitation. 7 patients (3.7%) died from sudden cardiac death. The actuarial survival at 10 years is 93% for simple TGA and 85% for TGA associated with ventricular septum defect or coarctation. At our institution, 4 adolescent or adult patients underwent tricuspid valve surgery; tricuspid valve replacement was performed in 2 patients and valve repair in 2 patients. In the mid-term follow-up, 2 of these patients died. Two additional patients underwent orthotopic heart transplantation, and one died on the waiting list. Staged conversion from the Senning/Mustard atrial repair to the arterial switch operation was initially reported by Mee. The procedure for pulmonary artery banding starts with inducing left ventricular reconditioning with subsequent arterial switch. The mortality of this two-staged procedure was as high as 20% to 30% in our early experience, and some of the candidates underwent heart transplantation. Tricuspid valve repair or replacement do not improve right ventricular function in patients with a failing right ventricle following the Mustard/Senning operation. Staged conversion to arterial switch may improve right ventricular function by decreasing the work load of the right ventricle and provides anatomic repair with left ventricle-to-aorta continuity. Orthotopic heart transplantation is the only alternative if the left ventricle does not respond to pulmonary artery banding.

The Arterial Switch-Operation: Early and Midterm (6 years) Results with Particular Reference to Technical Problems

Since February 1985 the arterial switch operation (ASO) has become the surgical treatment of choice for newborns with simple TGA, appropriate forms of complex TGA and double outlet right ventricle (DORV) as well at our institution. Between 1985 and 1990 a total of 87 patients underwent surgery. In 60 patients with simple TGA and 8 patients with complex TGA or DORV, respectively, an arterial switch-operation was performed. Because of coronary artery anomalies (n = 13), dysplastic pulmonary valves (n = 3) or pressure drop in the left ventricle (n = 1), the initially planned arterial switch operation was discarded and a Mustard type procedure was in 17 patient. Finally there were two primarily performed Mustard operations. The hospital mortality after arterial switch for simple TGA was 15% (9/60), 0/8 in patients with complex TGA. Late mortality was calculated to be 12% (1/8) in patients with complex TGA and 3/60 in patients with simple TGA. Within the Mustard group there were 2/19 hospital deaths and one late death. Causes of early death after arterial switch were: intraoperative myocardial infarct (n = 3) low cardiac output syndrome (n = 2), intractable bleeding (n = 2), metabolic acidosis (n = 1), and septicemia (n = 1). Late after surgery there was one death due to chylothorax after thrombotic obstruction of the SVC, and 3 more deaths secondary to intraoperative infarct, progressive LV dysfunction and meningitis, respectively. Among the long-term survivors 2 patients developed a severe supravalvulary pulmonary stenosis. There were no significant arrhythmias, supravalvulary pulmonary aortic stenoses, aortic insufficiency or myocardial perfusion disturbances.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of TGA to estimate the loading of organics on activated carbon

Activated carbon is used in the mining industry for the recovery of precious metals, and is used in the treatment of waste-waters for the removal of pollutants. During such applications the carbon becomes poisoned by a wide spectrum of organics of which the concentrations and identities are not usually known. A simple mass balance and TGA data can be used to calculate the loading of organics on activated carbon if the residual mass of pyrolysed organics is known; however, this information is not usually known for industrial carbons. In such cases the slope of the TGA curve for the loaded carbon heated above 850 °C in an inert atmosphere may be used to estimate the loading of organics on the carbon. Different carbons loaded with phenol, benzoic acid and methylene blue, as well as carbons loaded from plant solutions, were used to verify the use of this new procedure.

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Mustard procedure for simple transposition of the great arteries.

From May 1980 through April 1982, 9 patients underwent the Mustard operation for simple transposition of the great arteries (simple TGA) at the Tohoku University Hospital, Sendai. There was no early postoperative death, although one patient was lost with pulmonary venous obstruction in the late postoperative period. No pulmonary venous obstruction occurred since the introduction of expanded polytetrafluoroethylene (EPTFE) intraatrial baffle. Normal sinus rhythm has been preserved in all patients since direct, high superior vena cava cannulation was adopted. Postoperative hemodynamic study at an average 12 months after surgery revealed normal right ventricular function at rest. Work-function curve which is related to the right ventricular end-diastolic pressure and minute work index revealed good response of the right ventricle in two of three patients after methoxamine infusion test. All late survivors are acyanotic and clinically well. The Mustard procedure has dramatically improved the survival rate and quality of life for those with simple TGA. Presently, we continue to utilize the Mustard procedure for simple TGA until the superiority of other operations are demonstrated.

Further experience with the two-stage anatomic correction of simple transposition of the great arteries.

Between May 1976 and January 1981 a two-stage anatomic correction was performed in 25 patients with simple transposition of the great arteries, ranging in age from 41/2 to 46 1/2 months (mean 14.8). A first-stage operation, consisting of banding of the pulmonary artery to redevelop the left ventricle, including a Blalock-Taussig-anastomosis in 4 patients was performed prior to anatomic correction. Of 33 patients, who underwent first-stage correction there were 3 early deaths (9%). The interval between the first and second stages was 5 weeks to 9 months (mean 4.3 months). After the first-stage operation, the peak systolic left ventricular pressure rose from 34 +/- 11 mmHg to 80 +/- 16 mmHg with no significant change in enddiastolic pressure. After anatomic correction there were 5 early deaths (20%) of whom 4 were due to left heart failure. There was no correlation between death and the age of the patients at the time of anatomic correction. By our current criteria the ventricles were not adequately prepared for correction in these four patients. The coronary arteries, with different types of origin, could be reimplanted to the posterior vessels without kinking, tension or torsion in all cases. After correction, the ECG and vectorcardiogram rapidly changed toward normal. The arterial oxygen saturation was higher than 95% in all patients. Recatheterization performed in 11 patients, 3 weeks to 27 months after correction, showed normal left ventricular pressure at rest in all children, except in 2 recatheterized early after correction, who had moderately elevated left ventricular enddiastolic pressure. Right ventricular peak systolic pressure decreased to normal limits. The aortic and coronary anastomoses showed normal growth in cineangiography. Although the two-stage corrections of simple TGA may have its own problems, investigation suggests that results are encouraging.

Natural history and postoperative evaluation of complete transposition of the great arteries.

In a total of 107 cases with transposition of the great arteries (TGA-s), 20 died preoperatively and 76 underwent surgical treatment: 11 palliative and 65 primary corrective surgeries, with hospital mortality 36.4% and 46.2% respectively. Of 31 survivors after Mustard operation, tricuspid regurgitant murmur and ECG abnormalities were recognized at 26.7% and 33.3% respectively in simple TGA, and 62.5% and 37.5% respectively in complicated TGA during an average follow-up of 4 years. Angiocardiogram, performed more than 2 years postoperatively, revealed decreased ejection fraction (EF) with compensatory increase of right ventricular end-diastolic volume (RVEDV): EF 0.43 +/- 0.04, RVEDV 168 +/- 41% of normal in simple TGA and 0.36 +/- 0.12, 173 +/- 55% in complicated TGA. In 3 long-term survivors of arterial switch operation (Stansel, Kaye), no serious complications were observed, and ejection fraction and echocardiographic findings of systemic ventricle showed an earlier normalizing than in Mustard operation: EF 0.65 or more when no VSD leakage and pre-ejection period (PEP/ejection time (ET) 0.35 +/- 0.05 after switch operation, 0.45 +/- 0.05 in simple TGA and 0.47 +/- 0.07 in complicated TGA after Mustard operation. From these long-term postoperative evaluations, our policy at present is to prefer arterial switch operation to Mustard operation in corrective surgery for TGA.

Surgical treatment of transposition of the great arteries.

Between 1974 and 1979 171 patients with d-TGA were treated surgically, 109 had correcting operations. 77 patients with simple TGA had hemodynamic correction by atrial inversion techniques. 30 day survival rate was 96%. There were 3 late deaths. One patient had reoperation for superior vena cava obstruction. The methods of diagnosis, indication of surgery and the surgical procedure are described. Results of the Mustard technique (33 patients) technique in infants less than 2 years of age with simple TGA. Mortality was one patient in each group. The incidence of arrhythmia was greater with the senning technique. Better growth potential of the atria with the Senning technique warrants further use of this method.