Bilateral remote ischemic conditioning in children: A two-center, double-blind, randomized controlled trial in young children undergoing cardiac surgery.

Objective: The study objective was to determine whether adequately delivered bilateral remote ischemic preconditioning is cardioprotective in young children undergoing surgery for 2 common congenital heart defects with or without cyanosis. Methods: We performed a prospective, double-blind, randomized controlled trial at 2 centers in the United Kingdom. Children aged 3 to 36 months undergoing tetralogy of Fallot repair or ventricular septal defect closure were randomized 1:1 to receive bilateral preconditioning or sham intervention. Participants were followed up until hospital discharge or 30 days. The primary outcome was area under the curve for high-sensitivity troponin-T in the first 24 hours after surgery, analyzed by intention-to-treat. Right atrial biopsies were obtained in selected participants. Results: Between October 2016 and December 2020, 120 eligible children were randomized to receive bilateral preconditioning (n = 60) or sham intervention (n = 60). The primary outcome, area under the curve for high-sensitivity troponin-T, was higher in the preconditioning group (mean: 70.0 ± 50.9 µg/L/h, n = 56) than in controls (mean: 55.6 ± 30.1 µg/L/h, n = 58) (mean difference, 13.2 µg/L/h; 95% CI, 0.5-25.8; P = .04). Subgroup analyses did not show a differential treatment effect by oxygen saturations (pinteraction = .25), but there was evidence of a differential effect by underlying defect (pinteraction = .04). Secondary outcomes and myocardial metabolism, quantified in atrial biopsies, were not different between randomized groups. Conclusions: Bilateral remote ischemic preconditioning does not attenuate myocardial injury in children undergoing surgical repair for congenital heart defects, and there was evidence of potential harm in unstented tetralogy of Fallot. The routine use of remote ischemic preconditioning cannot be recommended for myocardial protection during pediatric cardiac surgery.

Performance of a single-ventricle home-monitoring programme: survival and predictors of adverse outcome.

INTRODUCTION AND BACKGROUND: Mortality between stages 1 and 2 single-ventricle palliation is significant. Home-monitoring programmes are suggested to reduce mortality. Outcomes and risk factors for adverse outcomes for European programmes have not been published. AIMS: To evaluate the performance of a home-monitoring programme at a medium-sized United Kingdom centre with regards survival and compare performance with other home-monitoring programmes in the literature. METHODS: All fetal and postnatal diagnosis of a single ventricle were investigated with in-depth analysis of those undergoing stage 1 palliation and entered the home-monitoring programme between 2016 and 2020. The primary outcome was survival. Secondary outcomes included multiple parameters as potential predictors of death or adverse outcome. RESULTS: Of 217 fetal single-ventricle diagnoses during the period 2016-2020, 50.2% progressed to live birth, 35.4% to stage 1 and 29.5% to stage 2. Seventy-four patients (including 10 with postnatal diagnosis) entered the home-monitoring programme with six deaths making home-monitoring programme mortality 8.1%. Risk factors for death were the hybrid procedure as the only primary procedure (OR 33.0, p < 0.01), impaired cardiac function (OR 10.3, p < 0.025), Asian ethnicity (OR 9.3, p < 0.025), lower mean birth-weight (2.69 kg versus 3.31 kg, p < 0.01), and lower mean weight centiles during interstage follow-up (mean centiles of 3.1 versus 10.8, p < 0.01). CONCLUSION: Survival in the home-monitoring programme is comparable with other home-monitoring programmes in the literature. Hybrid procedure, cardiac dysfunction, sub-optimal weight gain, and Asian ethnicity were significant risk factors for death. Home-monitoring programmes should continue to raise awareness of these factors and seek solutions to mitigate adverse events. Future work to generalise home-monitoring programme and single-ventricle fetus to stage 2 outcomes in the United Kingdom will require multi-centre collaboration.

Surgical Techniques and Outcomes in Patients With Intra-Cardiac Abscesses Complicating Infective Endocarditis.

Background: An intra-cardiac abscess is a serious complication of both native (NV-IE) and prosthetic valve infective endocarditis (PV-IE). Despite being an accepted indication for surgery, controversies remain regarding the optimal timing and type of operation. We aimed to report the outcomes of patients managed for intra-cardiac abscesses over more than a decade. Methods: Patients aged ≥18 years managed for intra-cardiac abscess between 1 January 2005 and 31 December 2017 were identified from a prospectively collected IE database. The primary outcome was 30-day mortality in operated patients and secondary outcomes were freedom from re-infection, re-operation and long-term mortality comparing those patients with aortic root abscess who underwent aortic valve replacement (AVR) and those who received aortic root replacement (ARR). Results: Fifty-nine patients developed an intra-cardiac abscess, and their median age was 55 (43-71) years; among them, 44 (75%) were men, and 10 (17%) were persons who injected drugs. Infection with beta-haemolytic streptococci was associated with NV-IE (p = 0.009) and coagulase-negative staphylococci with PV-IE (p = 0.005). Forty-four (75%) underwent an operation, and among those with aortic root abscess, 27 underwent AVR and 12 ARR. Thirty-day mortality was associated with infection with S. aureus (p = 0.006) but not the type or timing of the operation. Survival in operated patients was 66% at 1 year and 59% at 5 years. In operated patients, none had a relapse, although six developed late recurrence. Freedom from infection, re-operation and long-term mortality were similar in patients undergoing AVR compared to ARR. Conclusion: Patients diagnosed with intra-cardiac abscess who were not operated on had very poor survival. In those who underwent an operation, either by AVR or ARR based upon patient factors, imaging and intra-operative findings outcomes were similar.

Comparative analysis of surgical and percutaneous pulmonary valve implants over a 20-year period.

OBJECTIVES: Since percutaneous pulmonary valve implantation (PPVI) was introduced to prolong the lifetime of surgically placed right ventricular to pulmonary artery conduits, valve technology has evolved and the indications for PPVI expanded to native and larger right ventricular outflow tracts. We explore how indications, patient populations and outcomes compare to surgical pulmonary valve replacement (PVR). METHODS: This is a retrospective cohort study of PPVI and PVR procedures between 1998 and 2020 at a single UK centre. One hundred and twenty-eight patients underwent PPVI and 365 patients PVR. Primary outcome measures were survival, infective endocarditis and reintervention. RESULTS: The most common indication for PVR was replacement of the native pulmonary valve for pulmonary regurgitation whereas PPVI was more commonly used to treat pulmonary stenosis in a previously placed bioprosthetic conduit or valve. Treatment indications for PPVI expanded over the study to include the native right ventricular outflow tract. Survival was similar for PPVI and PVR (92% PPVI and 96.8% PVR at 5 years; 85.8% PPVI and 95.1% PVR at 10 years). Preprocedural New York Heart Association class 3 and 4 was the most important predictor of poor outcome. Annualized infective endocarditis rate was significantly higher for the Melody PPVI (0.024 vs 0.0024/person/year for PVR, P < 0.05). Both groups showed significant symptomatic improvement postprocedure with remodelling of ventricular volumes and improvement in cardiac output. Long-term follow-up for PVR showed half of patients will need replacement at 10-15 years post-index procedure. CONCLUSIONS: An increasing number of patients requiring PVR can now be treated percutaneously. A lifetime strategy for re-valving should be considered at the first valve implant.

The Ross-Konno operation for neonates and infants with severe aortic incompetence following treatment for critical aortic stenosis.

OBJECTIVES: Aortic valve stenosis in neonates and infants is associated with congestive cardiac failure, and balloon or surgical valvuloplasty provides relief of stenosis. Occasionally severe aortic insufficiency necessitates urgent aortic valve replacement. We reviewed our experience with the Ross-Konno procedure in patients <1 year. METHODS: Between October 2013 and May 2020, 36 patients underwent balloon (34) or surgical (2) aortic valvuloplasty for aortic stenosis. Six patients subsequently underwent a Ross-Konno procedure. The median age at operation was 55 (27-116) days and weight was 4.25 (2.5-12) kg. All patients were in severe cardiac failure and had a small aortic annulus with Z-score -3.1 (-1 to -4.4). RESULTS: There were no early or late deaths. At the latest follow-up at 39 (13-60) months, ventricular function had improved in all patients and no patient was on anti-failure medication. On echocardiography, there wasno more than trivial aortic regurgitation and no left ventricular outflow tract obstruction. One patient required right ventricle to pulmonary artery conduit replacement and one patient had homograft stenting. CONCLUSIONS: Despite the severe preoperative haemodynamic compromise, the urgent Ross-Konno procedure was associated with excellent operative survival and recovery of ventricular function. The need for reintervention to the pulmonary conduit remains a cause for concern.

Bilateral Remote Ischaemic Conditioning in Children (BRICC) trial: protocol for a two-centre, double-blind, randomised controlled trial in young children undergoing cardiac surgery.

INTRODUCTION: Myocardial protection against ischaemic-reperfusion injury is a key determinant of heart function and outcome following cardiac surgery in children. However, with current strategies, myocardial injury occurs routinely following aortic cross-clamping, as demonstrated by the ubiquitous rise in circulating troponin. Remote ischaemic preconditioning, the application of brief, non-lethal cycles of ischaemia and reperfusion to a distant organ or tissue, is a simple, low-risk and readily available technique which may improve myocardial protection. The Bilateral Remote Ischaemic Conditioning in Children (BRICC) trial will assess whether remote ischaemic preconditioning, applied to both lower limbs immediately prior to surgery, reduces myocardial injury in cyanotic and acyanotic young children. METHODS AND ANALYSIS: The BRICC trial is a two-centre, double-blind, randomised controlled trial recruiting up to 120 young children (age 3 months to 3 years) undergoing primary repair of tetralogy of Fallot or surgical closure of an isolated ventricular septal defect. Participants will be randomised in a 1:1 ratio to either bilateral remote ischaemic preconditioning (3×5 min cycles) or sham immediately prior to surgery, with follow-up until discharge from hospital or 30 days, whichever is sooner. The primary outcome is reduction in area under the time-concentration curve for high-sensitivity (hs) troponin-T release in the first 24 hours after aortic cross-clamp release. Secondary outcome measures include peak hs-troponin-T, vasoactive inotrope score, arterial lactate and central venous oxygen saturations in the first 12 hours, and lengths of stay in the paediatric intensive care unit and the hospital. ETHICS AND DISSEMINATION: The trial was approved by the West Midlands-Solihull National Health Service Research Ethics Committee (16/WM/0309) on 5 August 2016. Findings will be disseminated to the academic community through peer-reviewed publications and presentation at national and international meetings. Parents will be informed of the results through a newsletter in conjunction with a local charity. TRIAL REGISTRATION NUMBER: ISRCTN12923441.

Age over 35 years is associated with increased mortality after pulmonary valve replacement in repaired tetralogy of Fallot: results from the UK National Congenital Heart Disease Audit database.

OBJECTIVES: Many adults with repaired tetralogy of Fallot will require a pulmonary valve replacement (PVR), but there is no consensus on the best timing. In this study, we aim to evaluate the impact of age at PVR on outcomes. METHODS: This is a national multicentre retrospective study including all patients >15 years of age with repaired tetralogy of Fallot who underwent their first PVR between 2000 and 2013. The optimal age cut-off was identified using Cox regression and classification and regression tree analysis. RESULTS: A total of 707 patients were included, median age 26 (15-72) years. The mortality rate at 10 years after PVR was 4.2%, and the second PVR rate of 6.8%. Age at PVR of 35 years was identified as the optimal cut-off in relation to late mortality. Patients above 35 years of age had a 5.6 fold risk of death at 10 years compared with those with PVR under 35 years (10.4% vs 1.3%, P < 0.001), more concomitant tricuspid valve repair/replacement (15.1% vs 5.7%, P < 0.001) and surgical arrhythmia treatment (18.4% vs 5.9%, P < 0.001). In those under 50 years, there was an 8.7 fold risk of late death compared with the general population, higher for those with PVR after 35 than those with PVR below 35 years (hazard ratio 9.9 vs 7.4). CONCLUSIONS: Patients above 35 years of age with repaired tetralogy of Fallot have significantly worse mortality after PVR, compared with younger patients and a higher burden of mortality relative to the general population. This suggests that there are still cases where the timing of initial PVR is not optimal, warranting a re-evaluation of criteria for intervention.

Grown-up Congenital Heart Surgery in 1093 Consecutive Cases: A "Hidden" Burden of Early Outcome.

BACKGROUND: Surgery in grown-ups with congenital heart disease (GUCH) is characterized by complex anatomy, comorbidities, reoperations, and technical challenges. Although 30-day postoperative mortality is low, this measure might be insufficient to reflect adverse outcome monitoring. Our study aimed to establish whether prolonged intensive care unit (ICU) stay (≥7 days) and 6-month mortality were more clinically meaningful measures than 30-day mortality and to identify predictors of adverse outcome. METHODS: All consecutive GUCH patients from 1998 to 2015 were identified. Perioperative characteristics, diagnoses, and postoperative data were collected retrospectively. Predictors of 30-day and 6-month mortality and prolonged ICU stay were determined with logistic regression. Era effect was tested for quality assurances by dividing the cohort into 4 time intervals. RESULTS: Within 17 years, 1093 consecutive cardiac surgical procedures were identified in 1026 GUCH patients. During the study period, 30-day mortality improved significantly, with an overall 30-day mortality of 1.5%; 6-month mortality and prolonged ICU stay were 2.4% and 6.7%, respectively. Despite a decreased number of preoperative patients in New York Heart Association Functional Classification III or higher, prolonged ICU stay increased over the eras. Predictors of adverse outcome were New York Heart Association class III or higher, preoperative renal failure, disease of great complexity, preoperative ventilator support, cardiopulmonary bypass time, and concomitant procedures. CONCLUSIONS: In the current era of low 30-day mortality, extended 6-month mortality and prolonged ICU stay reporting may be more realistic measures of adverse outcomes for counseling GUCH patients at risk.

Factors associated with perioperative mortality in children and adolescents operated for tetralogy of Fallot: A sub-Saharan experience.

BACKGROUND: Patients with tetralogy of Fallot are now surviving to adulthood with timely surgical intervention. However, many patients in low-income countries have no access to surgical intervention. This paper reports the surgical access and perioperative mortality in a sub-Saharan center that was mainly dependent on visiting teams. METHODS: We reviewed records of patients operated from January 2009 to December 2014. We examined perioperative outcomes, primarily focusing on factors associated with perioperative mortality. RESULTS: During this period, 62 patients underwent surgery. Fifty-seven (91.9%) underwent primary repair, while 5 (6.5%) underwent palliative shunt surgery. Of the five patients with shunt surgery, four ultimately underwent total repair. Eight (12.9%) patients died during the perioperative period. Factors associated with perioperative mortality include repeated preoperative phlebotomy procedures (P < .001), repeated runs and long cardiopulmonary bypass time (P < .001), and aortic cross-clamp time (P < .001), narrow pulmonary artery (PA) valve annulus diameter (P = .022), narrow distal main PA diameter (P = .039), narrow left branch PA diameter (P = .049), and narrow right PA diameter (P = .039). Of these factors, cardiopulmonary bypass time/aortic cross-clamp time and pulmonary valve annulus diameter less than three SD were independently associated with perioperative mortality. CONCLUSION: In this series of consecutive patients operated by a variety of humanitarian surgical teams, cardiopulmonary bypass time/aortic cross-clamp time, and pulmonary valve annulus diameter less than three SD were independently associated with perioperative mortality risk. As some of these factors are modifiable, we suggest that they should be considered during patient selection and at the time of surgical intervention.

Reoperation for left atrioventricular valve failure in repaired atrioventricular septal defect: Can more valves be preserved in the current era?

OBJECTIVE: Left atrio-ventricular valve (LAVV) regurgitation after repair of an atrio-ventricular septal defect (AVSD) may necessitate further surgery. However, redo-LAVV repair remains challenging. We sought to determine if more LAVV valves are preserved in the current era, and analyze early and longer-term results. PATIENTS: All consecutive patients with repaired AVSD who underwent redo-LAVV surgery from January 2004 to April 2017 were included. Patients with single ventricles, atrial isomerism, and complex associated anomalies were excluded. METHODS: This was a single-center study using retrospective chart review and an institutional database for follow-up information. Data analyzed included number and year of primary AVSD and redo-LAVV operation, presence of trisomy 21, morphology of AVSD, mortality, and reoperation. Univariate analysis included repair and replacement rates and early and long-term survival. RESULTS: During the study period 36 redo-LAVV operations were performed, with repair in 28 and replacement in eight. The number of redo-operations increased from 13 in the first part to 23 in the second part of the study. The rate of LAVV preservation significantly increased over time (54% vs 91%, P < 0.01), and was not affected by morphology of AVSD or trisomy 21. There was one in-hospital death at Day 42 and overall estimated survival was 94.5% at 5 years. Freedom from reoperation after redo-LAVV repair was 87% at 5 years with no significant difference between repair and replacement groups. CONCLUSION: In the current era, more LAVVs can be preserved at the time of redo-operation with excellent early and long-term survival and acceptable reoperation rates. LAVV morphology and presence of trisomy 21 did not affect outcome.

Inadvertent ligation of the left pulmonary artery during intended ductal ligation.

BACKGROUND: Inadvertent ligation of the left pulmonary artery during attempted surgical closure of a Patent Ductus Arteriosus has long been recognized as one of the less common complications of this procedure. Surgical reconstruction of the left pulmonary artery was then often attempted but was difficult or impossible in some of the patients with hypoplasia of the left pulmonary artery and the left lung. CASE PRESENTATION: A 10-year-old girl presented with marked exercise intolerance and palpitations and was diagnosed to have large PDA. She had feeding difficulty, diaphoresis, failure to gain weight, recurrent chest infections during infancy and early childhood. Physical examination revealed an underweight child with wide pulse pressure and bounding peripheral pulses. She had active precordium with accentuated P2 and machinery murmur in the left 2nd intercostal space and mid diastolic rumble at the mitral area. Echocardiography showed a 12 mm patent arterial duct. She was taken for an intended surgical ligation of the duct but a control echocardiogram on the 3rd postoperative day revealed that the left pulmonary artery, instead of the duct, was ligated. Surgical reconstruction of the left pulmonary artery was undertaken 3 years later, however, this was complicated by post reconstruction left pulmonary artery stenosis. Successful percutaneous stenting of the left pulmonary artery was performed 18 months after the surgical reconstruction. CONCLUSION: The incidence of inadvertent LPA ligation may be underestimated where PDA ligation is done by less experienced surgeons and postoperative echocardiography is not routinely performed. Late correction of inadvertent LPA ligation is an important surgical challenge, especially if the duct is still patent. Percutaneous stenting as a primary option may carry significant risk, as the ligated pulmonary artery is fragile. In our case, a good result was achieved with surgical repair followed by percutaneous stenting.

Outcome in Children Operated for Membranous Subaortic Stenosis: Membrane Resection Plus Aggressive Septal Myectomy Versus Membrane Resection Alone.

BACKGROUND: The optimal surgical procedure for treatment of fibromembranous subaortic stenosis has been a subject of debate. We report our experience with patients treated for membranous subaortic stenosis using membrane resection alone and membrane resection plus aggressive septal myectomy. METHODS: Patients followed in the pediatric cardiology clinic of a university hospital, who had undergone surgery for subaortic stenosis between 2002 and 2013 were reviewed. Recurrence of subaortic membrane, residual left ventricular outflow gradient, and aortic valve function were analyzed. RESULTS: Forty-six patients underwent surgery for subaortic membrane. Of these, 19 had membrane resection plus aggressive septal myectomy, while 27 had membrane resection alone. Mean age at surgery for the membrane resection group was 7.7 ± 3.9 years and 10.9 ± 3.6 years for the membrane resection plus aggressive myectomy group. Preoperative subaortic gradient for the membrane resection group was 75.5 ± 26.7 mm Hg and 103.2 ± 39.7 mm Hg for the membrane resection plus aggressive myectomy group. The mean follow-up left ventricular outflow tract gradient was 42.3 ± 31.3 mm Hg in the membrane resection group, while it was 11.6 ± 6.3 mm Hg in the aggressive septal myectomy group. Nine patients from the membrane resection group had significant regrowth of the subaortic membrane during the follow-up period, while none of the aggressive septal myectomy group had detectable membrane on echocardiography. Seven of the nine patients with recurrence of the subaortic membrane underwent subsequent membrane resection plus aggressive septal myectomy. Intraoperative finding in all these redo cases was recurrence (growth) of a subaortic membrane. CONCLUSION: Aggressive septal myectomy offers less chance of recurrence, freedom from reoperation, and an improved aortic valve function. This is especially important in sub-Saharan settings where a chance of getting a second surgery is unpredictable.

Impact of combined clenbuterol and metoprolol therapy on reverse remodelling during mechanical unloading.

BACKGROUND: Clenbuterol (Cl), a ß2 agonist, is associated with enhanced myocardial recovery during left ventricular assist device (LVAD) support, and exerts beneficial remodelling effects during mechanical unloading (MU) in rodent heart failure (HF). However, the specific effects of combined Cl+ß1 blockade during MU are unknown. METHODS AND RESULTS: We studied the chronic effects (4 weeks) of ß2-adrenoceptor (AR) stimulation via Cl (2 mg/kg/day) alone, and in combination with ß1-AR blockade using metoprolol ((Met), 250 mg/kg/day), on whole heart/cell structure, function and excitation-contraction (EC) coupling in failing (induced by left coronary artery (LCA) ligation), and unloaded (induced by heterotopic abdominal heart transplantation (HATx)) failing rat hearts. Combined Cl+Met therapy displayed favourable effects in HF: Met enhanced Cl's improvement in ejection fraction (EF) whilst preventing Cl-induced hypertrophy and tachycardia. During MU combined therapy was less beneficial than either mono-therapy. Met, not Cl, prevented MU-induced myocardial atrophy, with increased atrophy occurring during combined therapy. MU-induced recovery of Ca2+ transient amplitude, speed of Ca2+ release and sarcoplasmic reticulum Ca2+ content was enhanced equally by Cl or Met mono-therapy, but these benefits, together with Cl's enhancement of sarcomeric contraction speed, and MU-induced recovery of Ca2+ spark frequency, disappeared during combined therapy. CONCLUSIONS: Combined Cl+Met therapy shows superior functional effects to mono-therapy in rodent HF, but appears inferior to either mono-therapy in enhancing MU-induced recovery of EC coupling. These results suggest that combined ß2-AR simulation +ß1-AR blockade therapy is likely to be a safe and beneficial therapeutic HF strategy, but is not as effective as mono-therapy in enhancing myocardial recovery during LVAD support.

A longer waiting game: bridging children to heart transplant with the Berlin Heart EXCOR device--the United Kingdom experience.

BACKGROUND: Mechanical circulatory support (MCS) is used to support children with end-stage heart failure to heart transplant. METHODS: This was a retrospective cohort study of 7 years' experience with the Berlin Heart (BH) EXCOR (Berlin Heart AG, Berlin Germany) paracorporeal ventricular assist device (VAD) in 2 United Kingdom (UK) pediatric heart transplant centers and the effect of this program on the UK pediatric heart transplant service. RESULTS: Of 102 children who received BH support, 84% survived to transplant or BH explant and 81% survived to discharge. Neither age nor duration of support influenced outcome. Stroke, ongoing requirement for ventilation while on BH, and diagnosis other than dilated cardiomyopathy were the only independent mortality risk factors. Children who weighed < 20 kg had significantly (p = 0.03) longer support times than bigger children. The number of children treated with a BH increased over time (p = 0.01). Currently > 50% of pediatric heart transplants are bridged with a BH; however, pediatric transplants per year have not increased significantly (p = 0.07) CONCLUSIONS: BH use in the UK has allowed significant increases in the number of children with end-stage heart failure who can be successfully bridged to transplant and the length of time they can be supported. The total number of transplants has not increased.

ECLS for children with late (post-discharge) rejection after heart transplantation.

Rejection with acute hemodynamic compromise after OHT is rare in children, and is associated with poor survival. We retrospectively reviewed the management, course and outcome of recipients with late (following initial hospital discharge) rejection with acute hemodynamic compromise who were supported on ECLS. Of 197 consecutive children undergoing OHT (84 male; mean [SD] age 8.3 [5.7] [range 0.1-18.8 yr]) between 2/2002 and 10/2012, 187 children survived and were discharged from hospital. Mean (SD) follow-up was 5.0 (3.1) (range 0.1-10.6) yr. During follow-up, seven presented with severe hemodynamic compromise after transplantation (of whom one patient had been transplanted elsewhere). All seven children, who presented in hemodynamic collapse with poor cardiac function refractory to inotropic support, were placed on ECLS-two following in-hospital cardiac arrest. The median duration of ECLS was 6 (range 5-15) days. All survived to decannulation, with one death from overwhelming sepsis 20 days after presentation. The median (range) duration (in days) of inotropic requirement post ECLS was 11 (5-27), the median ventilation time was 8 (7-30), median ICU length of stay was 14 (10-54), and median hospitalization was 24 (19-118). In all, ventricular function normalized (FS >28%) within 10 (7-22) days. There was significant short-term morbidity; however, over a median follow-up of 5.9 (range 0.7-9.2) yr, all survivors have good functional status with no significant apparent neurological sequelae. ECLS thus appears to be a good rescue therapy for children with severe acute rejection post OHT, refractory to conventional treatment, leading to good medium-term outcome.

Heterotopic abdominal heart transplantation in rats for functional studies of ventricular unloading.

INTRODUCTION: Chronic changes in mechanical load regulate long-term cardiac function. Chronic overload of the ventricle results in myocardial failure. Clinical use of ventricular assist devices shows that chronic reduction in load has a number of different consequences on the myocardium, including beneficial reverse remodeling as well as undesired remodeling (e.g., myocardial atrophy and fibrosis, both of which could have negative functional implications). The complex response to mechanical unloading necessitates reproducible animal models of mechanical unloading for use in the laboratory. This article aims to describe the operative technique of two animal models of mechanical unloading in detail, to enable the reproducible use of these animal models. METHODS: In 1964, Abbott et al first described the heterotopic abdominal heart transplantation technique as a means to study the biology of transplanted cardiac grafts. This involves an aorto-aortic anastomosis and a pulmonary artery to inferior vena cava anastomosis. In this model, the left ventricle is virtually completely volume unloaded, receiving only thebesian venous return, and substantially but not entirely pressure unloaded. In this report we describe two refined techniques for mechanical unloading of healthy or failing hearts based on experience with over 500 operations. RESULTS: We describe an operative technique, including cardioprotective strategies, that provides a model of mechanical unloading with no immunological rejection and allows measurements of parameters of myocardial structure and function for many months. We describe a refined technique that achieves a lesser degree of left ventricular volume unloading, involving transplantation of both heart and lungs via a single aorto-aortic anastomosis. CONCLUSIONS: This article is the first to describe these two techniques in sufficient detail to enable novices to attempt and understand these operations and the differences between them. The technique we describe provides an effective and reproducible model of complete and partial mechanical unloading.

Influence of ivabradine on reverse remodelling during mechanical unloading.

AIMS: Ivabradine (Iva) has shown beneficial structural and functional effects in clinical and experimental heart failure (HF), but its action in combination with mechanical unloading (MU), such as during treatment with left ventricular assist devices (LVAD), is unknown. The aim of this study was to investigate the effects of Iva during MU, in a rodent model of HF. METHODS AND RESULTS: We studied the chronic effects (4 weeks) of Iva (10 mg/kg/day) alone and in combination with MU [induced by heterotopic abdominal heart transplantation (HATx)] on whole-heart and cellular structure, function, and excitation-contraction (E-C) coupling in a rodent (rat) model of HF, 12 weeks post-left coronary artery (LCA) ligation. Effects of Iva were compared with those of ß-blockade using metoprolol [(Met), 250 mg/kg/day]. Iva, but not Met, reversed myocardial fibrosis, alone and in combination with MU. MU-induced restoration of deranged E-C coupling was enhanced by Iva to a greater extent than Met: both Iva and Met enhanced the recovery of the Ca(2+) transient amplitude and the sarcoplasmic reticulum (SR) Ca(2+) content, but Iva alone maintained MU-induced normalization of L-type Ca(2+) current and t-tubule abnormalities. Met prevented MU-induced reduction in the myocardial size (myocardial atrophy); Iva had no effect on this parameter. CONCLUSION: Iva shows beneficial structural and E-C coupling effects during MU: Iva reverses myocardial fibrosis and enhances the restoration of deranged E-C coupling, displaying more beneficial effects than that of Met. These results suggest that Iva may prove effective in enhancing functional recovery in heart failure patients receiving LVAD therapy.

Cardiomyocyte Ca2+ handling and structure is regulated by degree and duration of mechanical load variation.

Cardiac transverse (t)-tubules are altered during disease and may be regulated by stretch-sensitive molecules. The relationship between variations in the degree and duration of load and t-tubule structure remains unknown, as well as its implications for local Ca(2+)-induced Ca(2+) release (CICR). Rat hearts were studied after 4 or 8 weeks of moderate mechanical unloading [using heterotopic abdominal heart-lung transplantation (HAHLT)] and 6 or 10 weeks of pressure overloading using thoracic aortic constriction. CICR, cell and t-tubule structure were assessed using confocal-microscopy, patch-clamping and scanning ion conductance microscopy. Moderate unloading was compared with severe unloading [using heart-only transplantation (HAHT)]. Mechanical unloading reduced cardiomyocyte volume in a time-dependent manner. Ca(2+) release synchronicity was reduced at 8 weeks moderate unloading only. Ca(2+) sparks increased in frequency and duration at 8 weeks of moderate unloading, which also induced t-tubule disorganization. Overloading increased cardiomyocyte volume and disrupted t-tubule morphology at 10 weeks but not 6 weeks. Moderate mechanical unloading for 4 weeks had milder effects compared with severe mechanical unloading (37% reduction in cell volume at 4 weeks compared to 56% reduction after severe mechanical unloading) and did not cause depression and delay of the Ca(2+) transient, increased Ca(2+) spark frequency or impaired t-tubule and cell surface structure. These data suggest that variations in chronic mechanical load influence local CICR and t-tubule structure in a time- and degree-dependent manner, and that physiological states of increased and reduced cell size, without pathological changes are possible.