Comparison of waitlist and post-transplant outcomes in patients supported with total artificial heart versus continuous biventricular assist devices.

BACKGROUND: Durable biventricular support may be necessary to bridge patients with end-stage biventricular failure to heart transplantation. This study compares waitlist and post-transplant outcomes between patients supported with continuous flow, durable biventricular assist devices (BiVAD), and total artificial heart (TAH). METHODS: Using the UNOS registry, we analyzed adult (≥18 years old), first-time transplant candidates with TAH or BiVAD at the time of listing or transplantation from 10/1/2010-10/31/2020, with follow-up through 3/31/2022. Multivariable proportional subdistribution hazards models and cause-specific Cox proportional hazards models were used to compare death/deterioration or heart transplantation on the waitlist between cohorts. Kaplan-Meier and multivariable Cox proportional hazards model were used to evaluate one-year post-transplant survival and evaluate difference in outcomes based on annual transplant center volume. RESULTS: The waitlist cohort included a total of 228 patients (25% BiVAD). Waitlist outcomes between device types were similar. The transplanted cohort included a total of 352 patients (25% BiVAD). There was a trend towards worse one-year post-transplant survival in patients bridged with TAH versus BiVAD (log-rank p-value = 0.072) that persisted after adjusting for age, gender, policy, and removing dual-organ recipients (HR 1.94 (0.94, 3.98) p-value = 0.07). There was a difference in one-year post-transplant survival amongst TAH-bridged patients when stratified by annual transplant center volume (log-rank p-value = 0.013). One-year post-transplant survival between TAH-supported patients from high annual transplant volume centers and BiVAD-supported patients was similar (p-value = 0.815). CONCLUSIONS: BiVAD and TAH are reasonable support strategies with TAH implantation at high-volume transplant centers (51+ transplants/year) having similar 1-year post-transplant survival to BiVAD-supported patients.

Performance study of dual heart assisted control system based on SL-SMC physiological combination controller.

The main challenges of Biventricular Assist Devices (BiVAD) as a treatment modality for patients with Bicardiac heart failure heart failure are the balance of systemic blood flow during changes in physiological activity and the prevention of ventricular suction. In this study, a model of the Biventricular Circulatory System (BCS) was constructed and a physiological combination controller based on Starling-Like controller and Sliding Mode Controller (SMC) was proposed. The effects of the physiological controller on the hemodynamics of the BCS were investigated by simulating two sets of physiological state change experiments: elevated pulmonary artery resistance and resting-exercise, with constant speed (CS) control and combined Starling-like and PI control (SL-PI) as controllers. Simulation and experimental results showed that the Starling-like and Sliding Mode Control (SL-SMC) physiological combination controller was effective in preventing the occurrence of ventricular suction, providing higher cardiac output, maintain balance of systemic blood flow, and have higher response speed and robustness in the face of physiological state changes.

Biventricular assist device implant using biatrial cannulation for restrictive cardiomyopathy.

Preoperative calculations showed that the 9-mm inlet, 6-mm outlet, 25-cc pump chambers and 65-73 bpm would be optimal for a 5-year-old patient suffering from restrictive cardiomyopathy, with a body surface area of 0.59 m2 (1.5 L/min flow for a cardiac index of 2.5). After re-sternotomy and standard bicaval cannulation for cardiopulmonary bypass, the procedure was performed under normothermic conditions and on the beating heart. Biventricular support was established with the Berlin Heart Excor using biatrial cannulation. For left atrial cannulation, induced ventricular fibrillation was used. The 9-mm inlet cannulas were inserted into the left and right atria, respectively. The 6-mm outlet cannulas were implanted using 8-mm interposition vascular grafts for the aorta and the main pulmonary artery, respectively. Cannulas were tunnelled through the epigastric space, with systems crossing outside of the body. The 25-cc chambers were used for both right ventricular assist device and left ventricular assist device support, which subsequently showed full emptying and filling.

Giant cell myocarditis with prolonged cardiac standstill after drug-induced hypersensitivity syndrome: a case report.

Giant cell myocarditis (GCM) is a rare but fatal disease that can lead to cardiac failure. Survival with a cardiac standstill requires mechanical circulatory support or a biventricular assist device (BiVAD) and prolonged survival is extremely rare. Drug-induced hypersensitivity syndrome (DIHS) is a severe cutaneous adverse reaction. Some cases of DIHS are reportedly associated with the onset of GCM. We present a case of a 28-year-old woman who developed GCM during steroid tapering after DIHS. She went into continuous cardiac standstill but survived for 74 days under BiVAD support. Our case is noteworthy because the histopathologic specimens obtained on three occasions contributed to the diagnosis of this particular condition over time. We also reviewed previous literature on concomitant cases of GCM and DIHS. We found that two are potentially associated and most cases of GCM occur within 3 months of DIHS during steroid tapering.

The ProtekDuo in percutaneous peripheral venopulmonary-arterial ECMO and PROpella configuration for cardiogenic shock with biventricular failure.

This article describes a case study where a patient with ProtekDuo + oxygenator and Impella CP (PROpella) in biventricular failure and cardiogenic shock was reconfigured to venopulmonary-arterial (VP-A) extracorporeal membrane oxygenation (ECMO), secondary to leg ischemia. The ProtekDuo was subsequently used as double-lumen drainage cannula, returning blood into a newly percutaneously placed femoral arterial cannula, mimicking venoarterial (V-A) ECMO in VP-A configuration. The following day, an Impella 5.5 could be placed and the ProtekDuo was reconfigured back to its default venopulmonary (V-P) ECMO configuration, now again as PROpella with minimally invasive biventricular groin-free full mechanical circulatory support. However, while in VP-A, good drainage blood flows of up to 4.5 LPM could be achieved similar to the ProtekDuo forward flow. None of the lumens collapsed secondary to negative pressure in the system. Drainage through the ProtekDuo for VP-A ECMO is feasible and without complications for a 24-hour period. This new method extends the ProtekDuo's spectrum of use.

Cardiac recovery from COVID-19-associated fulminant myocarditis by extracorporeal biventricular assist.

We report a case of cardiac recovery from coronavirus disease 2019 (COVID-19)-associated fulminant myocarditis in a 48-year-old woman diagnosed with COVID-19 infection 4 days before, whose hemodynamic collapse were resuscitated first with venoarterial extracorporeal membranous oxygenation, followed by escalation to extracorporeal biventricular assist devices (ex-BiVAD) using two centrifugal pumps and an oxygenator. She was likely to be multisystem inflammatory syndrome in adults (MIS-A) negative. Cardiac contractility gradually recovered after the 9th day of ex-BiVAD support, and the patient was successfully weaned from ex-BiVAD on the 12th day of support. Due to postresuscitation encephalopathy, she was transferred to the referral hospital for rehabilitation with recovered cardiac function. The histopathology of the myocardial tissue showed smaller amounts of lymphocytes and more infiltration of macrophages. It is important to recognize two phenotypes of MIS-A+ or MIS-A-, with distinct manifestations and outcomes. It is also important to refer urgently such patients with COVID-19-associated fulminant myocarditis, showing different histopathology from usual viral myocarditis, with evolution toward refractory cardiogenic shock to a center with capability for advanced mechanical support to avoid a too-late cannulation. Learning objective: We should recognize the clinical course and histopathology of the multisystem inflammatory syndrome in adults phenotype of coronavirus disease 2019-associated fulminant myocarditis. We should urgently refer such patients with evolution toward refractory cardiogenic shock to a center with capability for advanced mechanical support, such as venoarterial extracorporeal membrane oxygenation, Impella (Abiomed, Danvers, MA, USA), and extracorporeal biventricular assist devices.

Safety issues with an inter-hospital transport of a patient with a Berlin Heart Excor biventircular assist device.

BACKGROUND: Interhospital transfers of pediatric patients on the Berlin Heart Excor have been published on an occasional basis. METHODS: Nowadays medicine evolves away from just feasibility towards quality and safety issues. Management tools like risk analysis have found their way into clinical practice. RESULTS: Exemplary, we present a case of a 20 months old boy on a Berlin Heart BiVAD Excor who underwent a 224 km ground transport. After a systematic review of the published literature, we describe our safety management with the aim was to provide highest quality of care for the transport. CONCLUSION: Besides a risk analysis, we also describe our training and simulation protocol.

Wound Infections in Adult Patients after Berlin Heart® EXCOR Biventricular Assist Device Implantation.

The Berlin Heart® EXCOR is a paracorporeal, pulsatile ventricular assist device used in patients of all age groups. However, adolescent and adult patients on EXCOR support are scarcely explored. Herein, we present a detailed description of infectious complications in this patient cohort. From 2006 to 2020, 58 patients received a biventricular assist device (BiVAD) at our institution and were included in this study. Postoperative infections were assessed after BiVAD implantation and subsequent heart transplantation (HTx). A Berlin Heart® EXCOR BiVAD was implanted as a bridge to transplantation in 58 patients (12-64 years). Most patients were INTERMACS I, and their median age was 49 years. Wound infections (WI) specific to the ventricular assist device (VAD) occurred in 31 (53.4%) patients with a mean time of 113 ± 155 days after BiVAD implantation. HTx was performed in 30 (51.7%) patients and thereof 10 (33.3%) patients developed at least one WI post-HTx. The mean time of WI after HTx was 17 ± 14 days. In four cases, WIs were caused by the same pathogen as before HTx. According to our institutional BiVAD wound classification, the mean wound score was 3. The VAD-specific wound infections were manageable and did not increase mortality nor precluded HTx in Berlin Heart® EXCOR patients. No specific risk factors for VAD-specific wound infections could be identified.

Impact of preoperative versus postoperative dialysis on left ventricular assist device outcomes: An analysis from the Society of Thoracic Surgeons Interagency Registry for Mechanically Assisted Circulatory Support database.

Objective: Chronic kidney disease and renal failure are common in patients being considered for left ventricular assist device support. We sought to evaluate the outcomes of patients undergoing left ventricular assist device implantation with preoperative dialysis and those with new-onset postoperative renal failure requiring dialysis. Methods: All patients (n = 14,090) undergoing primary left ventricular assist device implantation who were listed in the Interagency Registry for Mechanically Assisted Circulatory Support database (2014-2019) were evaluated. Landmark analysis then stratified patients alive at 1 month by preoperative dialysis and at 1 month postoperatively, preoperative dialysis only, postoperative dialysis only, and no dialysis. Results: Of 14,090 patients undergoing left ventricular assist device implantation, patients on dialysis (400%, 3%) preoperatively had significantly higher mortality at 1 month (18% vs 6%, P < .0001). However, of patients on preoperative dialysis, 131 (32.8%) no longer required dialysis at 1 month postoperatively and had long-term survival similar to patients who never required dialysis (no dialysis vs recovered, P = .13). Long-term survival was significantly worse in patients with persistent dialysis and new dialysis at 1 month postoperatively (P < .0001). Time to first stroke, major nondevice infection, any bleeding event, and gastrointestinal bleeding were all worse in patients on preoperative or postoperative dialysis (all P < .0001). Device infection, malfunction, or thrombosis was not associated with dialysis status (P > .05). Negative predictors of recovery include biventricular assist device (odds ratio, 0.20) and inotropes 1 week postimplant (odds ratio, 0.19). Conclusions: Preoperative renal failure is associated with 3 times higher mortality and worse morbidity in patients receiving a left ventricular assist device. However, one-third of patients with preoperative dialysis will recover renal function postimplant with similar long-term survival and quality of life as those without dialysis.

Long-term paracorporeal pulsatile mechanical circulatory support in adolescent and adult patients.

OBJECTIVES: Our goal was to analyse adverse events in adolescent and adult patients with the Berlin Heart EXCOR and to assess the outcome of a subsequent heart transplant (HTX). METHODS: From 2006 to 2020, a total of 58 patients (12-64 years old) received a biventricular assist device (BIVAD) at our institution and were included in this study. RESULTS: The causes of biventricular heart failure were nonischaemic cardiomyopathy (62.1%), ischaemic cardiomyopathy (22.4%) and myocarditis (15.5%). The median INTERMACS score was I (I-III). The median age was 49 years (interquartile range, 34-55 years), and 82.8% were male. Causes of death were multiorgan failure (25.0%), septic shock (17.9%), cerebral haemorrhage (14.3%), bleeding (14.3%) and embolic events (14.3%). Major bleeding was more frequent in the patients who died while on BIVADs (60.7 vs 6.7%, P < 0.001). Wound infections were more prevalent in HTX recipients (n = 21, 70.0%). After BIVAD thrombosis, 104 chamber exchanges were performed in 28 patients (48.3%). HTXs were performed in 52.6% of the patients after a BIVAD support time of 316 ± 240 days. The mean time to follow-up of 30 HTX recipients was 1722 ± 1368 days. One-, 6- and 12-month survival after an HTX were 96.7%, 90.0% and 76.7%, respectively. Long-term survival after 5 and 10 years was 69.7%. CONCLUSIONS: Pump thrombosis, infections and bleeding after receiving a BIVAD did not preclude a successful HTX. Although only 50% of patients with BIVADs were successfully given a transplant, long-term survival after an HTX in patients with BIVAD was noninferior compared to that of other recipients.

The trajectory of renal function following mechanical circulatory support and subsequent heart transplantation.

AIM: Patients with advanced heart failure (HF) frequently suffer from renal insufficiency. The impact of durable mechanical circulatory support (MCS) and subsequent heart transplantation (HTx) on kidney function is not well described. METHODS AND RESULTS: We studied patients with advanced HF who received durable MCS as bridge to transplantation (BTT) and underwent subsequent HTx at our centre between 1996 and 2018. Glomerular filtration rate (GFR) was measured by 51 Cr-EDTA or iohexol clearance during heart failure work-up; 3-6 months after MCS; and 1 year after HTx. Chronic kidney disease (CKD) was classified according to KDIGO criteria based on estimated GFR. A total of 88 patients (46 ± 15 years, 84% male) were included, 63% with non-ischaemic heart disease. The median duration of MCS-treatment was 172 (IQR 116-311) days, and 81 subjects were alive 1 year after HTx. Measured GFR increased from 54 ± 19 during HF work-up to 60 ± 16 mL/min/1.73 m2 after MCS (P < 0.001) and displayed a slight but nonsignificant decrease to 57 ± 22 mL/min/1.73 m2 1 year after HTx (P = 0.38). The trajectory of measured GFR did not differ between pulsatile and continuous flow (CF) pumps. Among patients 35-49 years and those who were treated in the most recent era (2012-2018), measured GFR increased following MCS implantation and subsequent HTx. Estimated GFR displayed a similar course as did measured GFR. CONCLUSIONS: In patients with advanced heart failure, measured GFR improved after MCS with no difference between pulsatile and CF-pumps. The total study group showed no further increase in GFR following HTx, but in certain subgroups, including patients aged 35-54 years and those treated during the latest era (2012-2018), renal function appeared to improve after transplant.

Tricuspid valve repair and mechanical right ventricular support in rescue left ventricular assist device implantations: Still a relevant issue.

Right ventricular failure (RVF) remains the main cause of morbidity and mortality following the implantation of continuous flow (CF) left ventricular assist devices. Apart from the difficulties inherent in assessing right ventricular function, other factors that may confound the prediction of RVF intraoperative events include concomitant surgical procedures, postoperative changes in pulmonary hemodynamics, evolving mechanical circulatory support (MCS) technology, shifts in the target population, and device settings. In this commentary, the role of concomitant tricuspid valve repair, early planned temporary or durable MCS have been discussed. A focus on the current modifications in CF ventricular assist devices designed for the left ventricle to make them suitable for right ventricular support has been set.

Bridging patients in cardiogenic shock with a paracorporeal pulsatile biventricular assist device to heart transplantation-a single-centre experience.

OBJECTIVES: We evaluated the outcome of patients in cardiogenic shock receiving a paracorporeal pulsatile biventricular assist device as a bridge to transplantation. METHODS: We performed a retrospective single-centre analysis of all patients who received a Berlin Heart Excor® at our institution between 2004 and 2019. RESULTS: A total of 97 patients (90 adults, 7 paediatric) were analysed. Eighty-four patients were in Interagency Registry for Mechanically Assisted Circulatory Support level 1 (80 adults, 4 paediatric). Diagnoses were dilated cardiomyopathy (n = 41), ischaemic cardiomyopathy (n = 17) or myocardial infarction (n = 4), myocarditis (n = 15), restrictive cardiomyopathy (n = 2), graft failure after heart transplant (n = 7), postcardiotomy heart failure (n = 5), postpartum cardiomyopathy (n = 3), congenital heart disease (n = 1), valvular cardiomyopathy (n = 1) and toxic cardiomyopathy (n = 1). All patients were in biventricular heart failure and had secondary organ dysfunction. The mean duration of support was 63 days (0-487 days). There was a significant decrease in creatinine values after assist device implantation (from 1.83 ± 0.79 to 1.12 ± 0.67 mg/dl, P = 0.001) as well as a decrease in bilirubin values (from 3.94 ± 4.58 to 2.65 ± 3.61 mg/dl, P = 0.084). Cerebral stroke occurred in 16 patients, bleeding in 15 and infection in 13 patients. Forty-eight patients died on support, while 49 patients could be successfully bridged to transplantation. Thirty-day survival and 1-year survival were 70.1% and 41.2%, respectively. CONCLUSIONS: A pulsatile biventricular assist device is a reasonable therapeutic option in cardiogenic shock, when immediate high cardiac output is necessary to rescue the already impaired kidney and liver function of the patient.

Usefulness of hybrid veno-arterial extracorporeal membrane oxygenation for lung ischemia-reperfusion injury after biventricular assist device implantation.

We experienced a case of fulminant myocarditis complicated by severe lung ischemia-reperfusion injury after switching from veno-arterial extracorporeal membrane oxygenation to biventricular assist device. We controlled lung blood flow by hybrid veno-arterial extracorporeal membrane oxygenation, which was established by modifying the biventricular assist device circuit without resternotomy, blood delivery to the pulmonary artery and blood removal from the left ventricle in addition to central veno-arterial extracorporeal membrane oxygenation, and accelerated lung recovery. The patient's lung damage and cardiac function were restored, and she completely recovered and was discharged without any complications. Regulation of lung blood flow is important and effective for lung ischemia-reperfusion injury after biventricular assist device implantation.

Outcomes of percutaneous temporary biventricular mechanical support: a systematic review.

Percutaneous biventricular assist devices (BiVAD) are a recently developed treatment option for severe cardiogenic shock. This systematic review sought to identify indications and outcomes of patients placed on percutaneous BiVAD support. An electronic search was performed to identify all appropriate studies utilizing a percutaneous BiVAD configuration. Fifteen studies comprising of 20 patients were identified. Individual patient survival and outcomes data were combined for statistical analysis. All 20 patients were supported with a microaxial LVAD, 12/20 (60%) of those patients were supported with a microaxial (RMA) right ventricular assist device (RVAD), and the remaining 8/20 (40%) patients were supported with a centrifugal extracorporeal RVAD (RCF). All patients presented with cardiogenic shock, and of these, 12/20 (60%) presented with a non-ischemic etiology vs 8/20 (40%) with ischemic disease. For the RMA group, RVAD support was significantly longer [RMA 5 (IQR 4-7) days vs RCF 1 (IQR 1-2) days, p = 0.03]. Intravascular hemolysis post-BiVAD occurred in three patients (27.3%) [RMA 3 (33.3%) vs RCF 0 (0%), p = 0.94]. Five patients received a durable left ventricular assist device, one patient received a total artificial heart, and one patient underwent a heart transplantation. Estimated 30-day mortality was 15.0%, and 78.6% were discharged alive. Both strategies for percutaneous BiVAD support appear to be viable options for severe cardiogenic shock.

Contemporary outcomes of continuous-flow biventricular assist devices.

BACKGROUND: Significant right ventricular failure (RVF) complicating left ventricular assist device (LVAD) placement has been reported at 10-30%. Although primarily indicated for left ventricular failure, ventricular assist devices (VADs) have become utilized in a biventricular setup to combat right ventricular failure (RVF) following LVAD implantation. With the advent of continuous-flow LVADs (CF-LVADs) superseding their pulsatile predecessors, the shift towards CF-biventricular assist devices (CF-BiVADs) come with the prospect of improved outcomes over previous pulsatile BiVADs. We aim to review the literature and determine the outcomes of CF-BiVAD recipients. METHODS: A systematic review was performed to determine the outcomes of CF-BiVADs. Pre-operative demographics and device configuration data was collected. Primary outcomes evaluated were short-term survival, long-term survival, duration of support, and survival to transplant. Secondary outcomes evaluated included intensive care unit (ICU) and hospital length of stay (ICU-LOS and HLOS, respectively), pump thrombosis, pump exchange. Median and interquartile range was reported where appropriate. A major limitation was the likely overlap of cohorts across publications, which may have contributed to some selection bias. RESULTS: Of 1,282 screened, 12 publications were evaluated. Sample size ranged from 4 to 93 CF-BiVAD recipients, and follow-up ranged from 6 to 24 months. Mean age ranged from 34 to 52 years old. Forty-five percent of CF-BiVADs had right atrial (RA-) inflow cannulation, with the remaining being right ventricular (RV). Thirty-day survival was a median of 90% (IQR 82-97.8%) and 12-month survival was a median of 58.5% (IQR 47.5-62%). Where reported, rate of pump thrombosis (predominantly the right VAD) was a median of 31% (IQR 14-36%), although pump exchange was only 9% (IQR 1.5-12.5%). CONCLUSIONS: RVF post-LVAD implantation is a high morbidity and mortality complication. There is no on-label continuous-flow RVAD currently available. Thus, the modifications of LVADs for right ventricular support to combat pump thrombosis has resulted in various techniques. BiVAD recipients are predominantly transplant candidates, and complications of pump thrombosis and driveline infection whilst on wait-list are of great consequence. This study demonstrates the need for an on-label CF-BiVAD.

Conventional and alternative sites for left ventricular assist device inflow and outflow cannula placement.

Left ventricular assist device (LVAD) therapy is a well accepted and effective strategy to treat advanced heart failure. The miniaturized third-generation centrifugal pumps HeartWare HVAD (Medtronic, Dublin, Ireland) and HeartMate 3 (Abbott, Illinois, USA) are the two most commonly implanted systems in the contemporary era. Their design has allowed clinicians to pioneer several alternate and less invasive implantation techniques to tackle a broad spectrum of clinical scenarios. A brief review and discussion of alternative surgical techniques for both inflow and outflow cannula insertion, in the contemporary LVAD surgery era, are herein reported.

Total percutaneous biventricular assist device implantation for fulminant myocarditis.

We report an effective therapeutic approach of mechanical circulatory support for a patient with cardiogenic shock and respiratory insufficiency due to fulminant myocarditis. An Impella® 5.0 was utilized as a left ventricular assist device (VAD) and percutaneous veno-pulmonary extracorporeal membrane oxygenation (ECMO) as a right VAD. These devices were implanted without sternotomy or thoracotomy. Although a combination of Impella and veno-arterial ECMO has been reported as percutaneous biventricular support, there are concerns that this combination is not beneficial for myocardial recovery in patients with respiratory insufficiency, because Impella expels insufficiently oxygenated blood from the left ventricle to the coronary arteries. Our approach took advantage of percutaneous implantation of ECMO and temporary VAD, eliminating the drawbacks of both devices, thus providing a more effective and less invasive form of temporary biventricular support.

Durable circulatory support with a paracorporeal device as an option for pediatric and adult heart failure patients.

OBJECTIVES: Not all patients in need of durable mechanical circulatory support are suitable for a continuous-flow left ventricular assist device. We describe patient populations who were treated with the paracorporeal EXCOR, including children with small body sizes, adolescents with complex congenital heart diseases, and adults with biventricular failure. METHODS: Information on clinical data, echocardiography, invasive hemodynamic measurements, and surgical procedures were collected retrospectively. Differences between various groups were compared. RESULTS: Between 2008 and 2018, a total of 50 patients (21 children and 29 adults) received an EXCOR as bridge to heart transplantation or myocardial recovery. The majority of patients had heart failure compatible with Interagency Registry for Mechanically Assisted Circulatory Support profile 1. At year 5, the overall survival probability for children was 90%, and for adults 75% (P = .3). After we pooled data from children and adults, the survival probability between patients supported by a biventricular assist device was similar to those treated with a left ventricular assist device/ right ventricular assist device (94% vs 75%, respectively, P = .2). Patients with dilated cardiomyopathy had a trend toward better survival than those with other heart failure etiologies (92% vs 70%, P = .05) and a greater survival free from stroke (92% vs 64%, P = .01). Pump house exchange was performed in nine patients due to chamber thrombosis (n = 7) and partial membrane rupture (n = 2). There were 14 cases of stroke in eleven patients. CONCLUSIONS: Despite severe illness, patient survival on EXCOR was high, and the long-term overall survival probability following heart transplantation and recovery was advantageous. Treatment safety was satisfactory, although still hampered by thromboembolism, mechanical problems, and infections.