Left Ventricular Physiology and Ventricular-Vascular Interactions in Young Patients After Heart Transplantation.

Background In patients after heart transplantation, systemic arterial hypertension and enhanced central aortic stiffness contribute to increased ventricular afterload, which might lead to graft dysfunction. The aim of our study was to characterize systemic arterial elastance and its impact on left ventricular function and ventriculo-arterial coupling in a cohort of children, adolescents, and young adults after heart transplantation using invasive conductance catheter technique. Methods and Results Thirty patients who had heart transplants (age, 20.0±6.5 years, 7 female) underwent invasive cardiac catheterization including pressure-volume loop analysis. Load-independent parameters of systolic (ventricular elastance [Ees]) and diastolic (ventricular compliance) function as well as systemic arterial elastance (Ea, end-systolic pressure/stroke volume) and ventriculo-arterial coupling (Ea/Ees) were assessed at baseline level and during dobutamine infusion (10 µg/kg/min). Ees showed an appropriate increase under inotropic stimulation from 0.43 (0.11-2.52) to 1.00 (0.20-5.10) mm Hg/mL/m2 (P<0.0001), whereas ventricular compliance remained rather unchanged (0.16±0.10 mm Hg/mL/m2 to 0.12±0.07 mm Hg/mL/m2; P=0.10). Ventriculo-arterial coupling Ea/Ees was abnormal at rest and did not improve significantly under dobutamine (1.7 [0.6-6.7] to 1.3 [0.5-4.9], P=0.70) due to a simultaneous rise in Ea from 0.71 (0.37-2.82) to 1.10 (0.52-4.03) mm Hg/mL/m2 (P<0.0001). Both Ees and ventricular compliance were significantly associated with Ea at baseline and under dobutamine infusion. Conclusions Patients who underwent heart transplantation show impaired ventriculo-arterial coupling at rest and under inotropic stimulation despite preserved left ventricular contractile reserve. An abnormal response in vascular function resulting in increased afterload seems to represent an important factor that may play a role for the development of late graft failure.

Exercise-dependent changes in ventricular-arterial coupling and aortopulmonary collateral flow in Fontan patients: a real-time CMR study.

AIMS: Inefficient ventricular-arterial (V-A) coupling has been described in Fontan patients and may result in adverse haemodynamics. A varying amount of aortopulmonary collateral (APC) flow is also frequently present that increases volume load of the single ventricle. The aim of the study was to assess changes in V-A coupling and APC flow during exercise CMR. METHODS AND RESULTS: Eighteen Fontan patients (age 24 ± 3 years) and 14 controls (age 23 ± 4 years) underwent exercise CMR using a cycle ergometer. Ventricular volumetry and flow measurements in the ascending aorta (AAO), inferior (IVC), and superior (SVC) vena cava were assessed using real-time sequences during stepwise increases in work load. Measures of systemic arterial elastance Ea, ventricular elastance Ees, and V-A coupling (Ea/Ees) were assessed. APC flow was quantified as AAO - (SVC + IVC). Ea remained unchanged during all levels of exercise in both groups (P = 0.39 and P = 0.11). Ees increased in both groups (P = 0.001 and P < 0.001) with exercise but was lower in the Fontan group (P = 0.04). V-A coupling was impaired in Fontan patients at baseline (P = 0.04). Despite improvement during exercise (P = 0.002) V-A coupling remained impaired compared with controls (P = 0.001). Absolute APC flow in Fontan patients did not change during exercise even at maximum work load (P = 0.98). CONCLUSIONS: Inefficient V-A coupling was already present at rest in Fontan patients and aggravated during exercise due to a limited increase in ventricular contractility which demonstrates the importance of a limited functional reserve of the single ventricle. APC flow remained unchanged suggesting no further increase in volume load during exercise.

Prenatal Diagnosis and Postnatal Outcome of Eight Cases with Criss-Cross Heart - A Multicenter Case Series.

OBJECTIVE: Criss-cross heart (CCH) is a rare congenital cardiac defect defined by crossing of ventricular inflow streams contributing to less than 0.1 % of all congenital heart anomalies. Due to its rarity and complexity, prenatal diagnosis in these patients remains challenging. We sought to describe prenatal findings and postnatal course in eight cases of prenatally diagnosed CCH. METHODS: This is a retrospective case series of prenatally diagnosed CCH in three centers between 2010-2017. We reviewed fetal echocardiograms as well as postnatal clinical charts and surgical reports. RESULTS: 8 cases of CCH were included. The median gestational age at diagnosis was 27 weeks. 7 patients were found with situs solitus, one fetus with situs ambiguous. In all patients, the four-chamber view was abnormal. There was atrioventricular discordance in half of the patients, while all patients showed ventriculoarterial discordance. All patients were found with additional cardiac anomalies, including ventricular septal defect, double outlet right ventricle, right aortic arch, atrial septal defect and pulmonary stenosis. Three patients underwent amniocentesis without pathological findings. All patients were born alive at a median gestational age of 38 + 2 weeks and survived our median follow-up of 181 days. CONCLUSION: CCH can be diagnosed prenatally by detailed fetal echocardiography when observing an abnormal four-chamber view with crossing of inflow streams into both ventricles and a lack of parallel orientation of the atrioventricular valve axis due to a clockwise or counterclockwise rotation of the ventricular mass along its axis. With the help of prenatal ultrasound, parental guidance and counselling as well as postnatal pediatric cardiac management can be warranted.

Successful Management of an Infant with Atypical Presentation of Alveolar Capillary Dysplasia with Misalignment of the Pulmonary Veins.

A newborn infant patient presented with persistent pulmonary hypertension. For right ventricular decompression, the ductus arteriosus was kept open by prostaglandin E 1 infusion and was stented at the age of 4 weeks during heart catheterization. The child was weaned from mechanical ventilation, since pulmonary functions were adequate. A small atrial septal defect was identified and closed in cardiac catheterization laboratory to decrease preductal hypoxemia. Diagnostic workup led to the diagnosis of alveolar capillary dysplasia with misalignment of the pulmonary veins. Suprasystemic pulmonary arterial hypertension with persisting nitric oxide dependency remained the leading symptoms. The child underwent bilateral lung transplantation at the age of 28 months. He is well at the age of 44 months.

Cardiovascular Drug Therapy during Interstage After Hybrid Approach: A Single-Center Experience in 51 Newborns with Hypoplastic Left Heart.

BACKGROUND: Newborns with hypoplastic left heart (HLH) are usually palliated with the Norwood procedure or a hybrid stage I procedure. Hybrid is our preferred approach. Given the critical relationship between stage I, interstage, and comprehensive stage II or advanced biventricular repair, we hypothesized that appropriate drug treatment is a significant therapeutic cornerstone, especially for the management of the high-risk interstage. METHODS: We report a single-center observational study addressing the cardiovascular effects of, in particular, oral ß-blockers and the additional use of angiotensin-converting enzyme (ACE) and mineralocorticoid inhibitors. RESULTS: In total, 51 newborns-30 with HLH syndrome (HLHS) and 21 with HLH complex (HLHC)-with a median bodyweight of 3.0 kg (range 1.9-4.4; nine with bodyweight ≤ 2500 g) underwent an uneventful "Giessen hybrid approach" using a newly approved duct stent. All patients were discharged home with a single, double or triple therapy consisting of ß-blockers, ACE and mineralocorticoid inhibitors; 90% of the patients received bisoprolol, 10% received propranolol, 72% received lisinopril, and 78% received spironolactone. Resting heart rate decreased from 138 bpm (range 112-172; n = 51) at admission to 123 bpm (range 99-139; n = 51) at discharge and 110 bpm before stage II/biventricular repair/heart transplantation (range 90-140; n = 37) accompanied by favorable bodyweight gain. No side effects were evident. CONCLUSION: In view of drug risk/benefit profiles, as well as the variable morphology and hemodynamics, the highly selective ß1-adrenoceptor blocker bisoprolol is our preferred drug for treatment of HLHS/HLHC in the interstage. We avoid using ACE inhibitor monotherapy and exclude potential risks for coronary and cerebral perfusion pressure beforehand.

Natural history of pulmonary atresia with intact ventricular septum (PAIVS) and critical pulmonary stenosis (CPS) and prediction of outcome.

OBJECTIVES: To analyse prenatal parameters predicting biventricular (BV) outcome in pulmonary atresia with intact ventricular septum/critical pulmonary stenosis (PAIVS/CPS). METHODS: We evaluated 82 foetuses from 01/08 to 10/18 in 3 centres in intervals 1 (< 24 weeks), 2 (24-30 weeks) and 3 (> 30 weeks). RESULTS: 61/82 (74.4%) were livebirths, 5 (8.2%) lost for follow-up, 3 (4.9%) had compassionate care leaving 53 (64.6% of the whole cohort and 86.9% of livebirths) with intention to treat. 9 died, 44/53 (83.0%) survived. 24/38 (63.2%) with information on postnatal outcome had BV outcome, 14 (36.8%) non-BV outcome (2 × 1.5 circulation). One with BV outcome had prenatal valvuloplasty. Best single parameter for BV outcome was tricuspid/mitral valve (TV/MV) ratio (AUC 0.93) in intervals 2 and 3 (AUC 0.92). Ventriculo-coronary-arterial communications (VCAC) were present in 11 (78.6%) in non-BV outcome group vs. 2 (8.3%) in BV outcome group (p < 0.001). Tricuspid insufficiency (TI)-Vmax > 2.5 m/s was present in BV outcome group in75.0% (18/24) vs. 14.3% (2/14) in non-BV outcome group. Including the most predictive markers (VCAC presence, TI- Vmax < 2.5 m/s, TV/MV ratio < cutoff) to a score, non-BV outcome was correctly predicted when > 1 criterion was fulfilled in all cases. After recently published criteria for foetal intervention, only 4/9 (44.4%) and 5/14 (35.7%) in our interval 2 + 3 with predicted non-BV outcome would have been candidates for intervention. Two (1 × intrauterine intervention) in interval 2, two in interval 3 reached BV outcome and one 1.5 circulation without intervention. CONCLUSION: TV/MV ratio as simple parameter has high predictive value. After our score, non-BV outcome was correctly predicted in all cases. Criteria for foetal intervention must further be evaluated.

Impact of aortopulmonary collateral flow and single ventricle morphology on longitudinal hemodynamics in Fontan patients: A serial CMR study.

BACKGROUND: Single ventricle (SV) patients with a Fontan circulation are at risk for functional deterioration. The aim of this study was to assess longitudinal Fontan hemodynamics using serial cardiovascular magnetic resonance (CMR) data and to study the impact of aortopulmonary collateral (APC) flow and type of SV morphology. METHODS: Forty-one Fontan patients (age at first CMR 13.4 ± 6.0 years) with two CMR examinations within a time interval of at least 4 years (follow-up 5.3 ± 0.9 years) were included. The protocol consisted of short-axis cine volumetry and 2-dimensional blood flow measurements in the inferior vena cava (IVC), superior vena cava (SVC) and ascending aorta (Ao). APC flow was calculated as Ao - (SVC + IVC). Myocardial strain/strain rate was assessed using feature tracking technique. RESULTS: SV end-diastolic volume (p = 0.14) and ejection fraction (p = 0.70) remained constant. No significant changes in CMR derived myocardial strain/strain rate values were observed. Ao flow decreased (p = 0.01), IVC flow remained unchanged (p = 0.52), while SVC flow (p = 0.003) and APC flow (p = 0.006) decreased significantly. Patients with a systemic right ventricle (RV) showed unchanged APC flow and a further increase in SV size over time compared to patients with a systemic left ventricle. CONCLUSIONS: Longitudinal CMR data in a cohort of clinically stable Fontan patients revealed no significant changes in SV dimensions and myocardial performance while APC flow decreased spontaneously. Patients with a systemic RV seem to be at risk for permanent SV volume overload through APCs and might therefore benefit from consequent interventional APC embolization.

Outcome and Associated Findings in Individuals with Pre- and Postnatal Diagnosis of Tetralogy of Fallot (TOF) and Prediction of Early Postnatal Intervention.

PURPOSE: The aim of our retrospective evaluation was to compare the outcome of patients with prenatal and postnatal diagnosis of Tetralogy of Fallot (TOF) and to analyze prenatal echocardiographic parameters predicting intervention within 30 days postnatal. MATERIALS AND METHODS: We evaluated 142 patients in our pediatric heart center and prenatal diagnosis center and prenatal practice Praenatal plus in Cologne between 01/08-06/16. RESULTS: Within the prenatal diagnosis group, 6/74 fetuses (8.1 %) had TOF with pulmonary atresia (TOF-PA), and 6 (8.1 %) had absent pulmonary valve syndrome (TOF-APVS). 14 (18.9 %) had an abnormal karyotype including 9/14 (64.3 %) with microdeletion 22q11.2. 25 (33.8 %) had extracardiac malformation. 4 (5.4 %) had agenesis of ductus arteriosus (DA), 22 (29.7 %) had right aortic arch (RAA) and 9 (12.2 %) had major aortopulmonary collateral arteries (MAPCAs). Within the postnatal diagnosis group, no patient had TOF-PA, 4/68 (5.9 %) had TOF-APVS. 12 (17.6 %) had extracardiac malformations, 9 (13.2 %) had an abnormal karyotype including 2/9 with microdeletion 22q11.2. 10 (14.7 %) had RAA, 9 (13.2 %) had MAPCAs. There were no cases with agenesis of DA. Increasing z-score values of the left/right pulmonary artery (LPA/RPA) prenatally were associated with a lower probability for early postnatal intervention (RPA: p = 0.017; LPA: p = 0.013). Within the prenatal diagnosis group, 12 of 41 (29.3 %) live-born patients with follow-up and intention to treat needed early intervention versus 7 (10.3 %) in the postnatal diagnosis group (p = 0.02). Within the postnatal diagnosis group, there were no deaths, while 2 (4.9 %) post-intervention deaths occurred in the prenatal diagnosis group. CONCLUSION: There are no significant differences concerning post-intervention survival in the prenatal diagnosis group versus the postnatal diagnosis group. Complex cases may be underrepresented in the postnatal diagnosis group. Smaller RPA/LPA values prenatally seem to be associated with early postnatal intervention.

Severe heart failure and the need for mechanical circulatory support and heart transplantation in pediatric patients with myocarditis: Results from the prospective multicenter registry "MYKKE".

Myocarditis represents an important cause for acute heart failure. MYKKE, a prospective multicenter registry of pediatric patients with myocarditis, aims to gain knowledge on courses, diagnostics, and therapy of pediatric myocarditis. The role of mechanical circulatory support (MCS) in children with severe heart failure and myocarditis is unclear. The aim of this study was to determine characteristics and outcome of patients with severe heart failure requiring MCS and/or heart transplantation. The MYKKE cohort between September 2013 and 2016 was analyzed. A total of 195 patients were prospectively enrolled by 17 German hospitals. Twenty-eight patients (14%) received MCS (median 1.5 years), more frequently in the youngest age group (0-2 years) than in the older groups (P < 0.001; 2-12 and 13-18 years). In the MCS group, 50% received a VAD, 36% ECMO, and 14% both, with a survival rate of 79%. The weaning rate was 43% (12/28). Nine (32%) patients were transplanted, one had ongoing support, and six (21%) died. Histology was positive for myocarditis in 63% of the MCS group. Patients within the whole cohort with age <2 years and/or ejection fraction <30% had a significantly worse survival with high risk for MCS, transplantation, and death (P < 0.001). Myocarditis represents a life-threatening disease with an overall mortality of 4.6% in this cohort. The fulminant form more often affected the youngest, leading to significantly higher rate of MCS, transplantation, and mortality. MCS represents an important and life-saving therapeutic option in children with myocarditis with a weaning rate of 43%.

Percutaneous pulmonary valve implantation (PPVI) in non-obstructive right ventricular outflow tract: limitations and mid-term outcomes.

BACKGROUND: Percutaneous pulmonary valve implantation (PPVI) has been established as a safe and effective alternative to surgery treating patients with a failing pulmonary valve conduit. Nevertheless, the majority of patients in need of a valve have a native, non-obstructive right ventricular outflow tract (RVOT). The current approved stent-valves have a balloon-expandable design. Pre-stenting of the RVOT to create a landing zone and also protect the valve stability is usually mandatory; large, non-obstructive RVOTs need pre-stenting to reduce the RVOT-diameter for a balloon-expandable valve implantation. METHODS: A retrospective study design was used to analyze the medium-term outcome after PPVI in a series of 26 patients with native or reconstructed RVOT. RESULTS: PPVI was successfully performed in all, but 1 (96%). Within the follow-up of a minimum of 2 years, the percutaneous implanted valves remained competent; a significant pressure gradient was not detected. Furthermore, no PPVI-related complications such as endocarditis, migration or stent fractures were observed. The electrocardiogram at rest, in particular the QRS duration remained unchanged immediate post-PPVI as well as at medium-term follow-up of 24 months. However, ventricular arrhythmias were documented in 3 patients (11.5%); all patients were successfully treated with antiarrhythmic drugs, utilizing metoprolol. A trial of an invasive catheter based RVOT-ablation in one remained unsuccessful; pre-stented RVOT did not allow a successful intervention. CONCLUSIONS: Medium-term follow-up showed excellent results of the mechanical valve function. PPVI utilizing balloon-expandable stent-valves in a native RVOT remains an off-label use. Despite our encouraging results, advanced manipulations of the patched or native RVOT might be associated with significant ventricular arrhythmias. There is a need for less invasive RVOT reduction devices.

Acute therapy of newborns with critical congenital heart disease.

Critical congenital heart disease (cCHD) is the most common reason for acute cardiac failure in the neonatal period. cCHD, defined by systemic low cardiac output (LCO) and requiring surgery or catheter-based intervention in the first year of life, has an incidence of approximately 15% of CHD and is responsible for up to 25% fatalities of newborn infants. Clinical deterioration develops in most cases due to rapid closure of the ductus arteriosus (DA). Early diagnosis and immediate treatment determinate beneficial outcome. Critical CHD can be classified in duct-dependent systemic flow, duct-dependent pulmonary flow and transposition of the great arteries. The latter two manifest themselves in oxygen resistant cyanosis, whereas CHD with duct-dependent systemic flow may present itself with cardiogenic shock, which can be difficult to differentiate from other causes of shock such as sepsis. Besides prostaglandin therapy for reopening the arterial duct, a balanced parallel pulmonary and systemic circulation should be a therapeutic goal. In CHD with duct-dependent systemic flow a decrease of pulmonary resistance should be avoided; therefore inadequate oxygen therapy, hyperventilation and alkalosis due to excessive treatment of acidosis, should be averted. Volume therapy should be performed carefully. In CHD with duct-dependent pulmonary flow, pulmonary resistance can be decreased, in case of poor pulmonary flow systemic resistance should be increased, mild alkalosis is recommended. Intense volume therapy is in most cases necessary, except if a restrictive atrial communication is present. In addition to intensive care measures, an arsenal of catheter- and surgery-based procedures need to be hold available as back-up for emergency procedures. Transcatheter interventions are nowadays decisive. Atrial-septostomy was the first and still the most utilized high-urgency procedure; DA-stenting is used in prostaglandin-refractory duct stenosis. In the presence of critical aortic valve stenosis, palliation consists of balloon valvuloplasty. In critical aortic coarctation with myocardial failure and no response to prostaglandin, palliative balloon angioplasty may be the method of choice as bridging for corrective surgery.

Regenerative therapies in young hearts with structural or congenital heart disease.

Pediatric heart failure (HF) is rare. The prognosis is generally poor. HF is most frequently related to cardiomyopathy or congenital heart disease (CHD). Associated phenotypes are HF with preserved (HFpEF) or reduced ejection fraction (HFrEF); both in children with biventricular or univentricular circulation. Cardiac growth, differentiation, proliferation and consecutively regenerative and repair mechanisms are inversely related to the patient's age; edaphic and circulating cardiac progenitor cells as well; in sum, there are enormous endogenous potentials repairing a diseased heart in particular in young children. Efforts supporting pediatric cardiac regeneration are clearly justified; cell-based therapies have been addressed in small series of children with end-stage HF of either the left or right ventricle, more recently in randomized clinical trials. Different cell populations like autologous bone marrow mononuclear cells, progenitor cells or cardiac derived cells have been injected into coronaries or directly into the myocardium. Beneficial at least transient improvement of cardiac function was observed in patients with dilative cardiomyopathy and CHD, mainly hypoplastic left heart syndrome (HLHS). Cellular repopulation and possibly more crucial, paracrine effects contributed in slowing down progression of pediatric end-stage HF. Our review summarizes the current knowledge in different scenarios of HF by cell-based cardiac therapies in critically ill children. Based on the actual clinical experience future work to distinguish responders from non-responders among other refinements will lead to individualized precision treatment of HF in children, what means a lot to a child on a long list waiting for heart transplantation (HTX).

A word of caution: diabolic behaviour of AndraStents®: inflation of supporting balloon leads to "diabolo"-misconfiguration of the stent.

AIMS: Transcatheter implantation of pulmonary balloon-expandable stent-valves requires pre-stenting of the right ventricular outflow tract with large calibre stents. To increase awareness of the associated risks of this part of transcatheter pulmonary valve replacement therapy, we report potential fatal complications during the implantation of AndraStents® in the right ventricular outflow tract in six cases from five different European institutions and their management. METHOD AND RESULT: We present a retrospective case series analysis looking at the time period from 2013 to 2018. Of 127 AndraStents® implanted in the right ventricular outflow tract, in six patients, age from 13 to 71 years, a misconfiguration of the AndraStent® occurred forming a "diabolo"-configuration. During inflation of the balloon, the stent showed extreme "dog-boning", an expansion of the stent at both ends with the middle part remaining unexpanded. This led to rupture of the balloon and loss of manoeuvrability in four patients. Out of the total six cases, in four patients the stent was eventually expanded with high-pressure balloons, and in one case the stent was surgically retrieved. In one patient, in whom a percutaneous retrieval of the embolised stent was attempted, a fatal bleeding occurred. CONCLUSIONS: Pre-stenting of the right ventricular outflow tract by AndraStents® can lead to misconfiguration of the stent with potentially fatal complications. Rescue strategies of misconfigured stents include stent inflation and placement with high pressure non-compliant balloons or surgical backup. Interventional retrieval measures of AndraStents® cannot be advised.

Effect and safety of treatment with ACE-inhibitor Enalapril and ß-blocker metoprolol on the onset of left ventricular dysfunction in Duchenne muscular dystrophy - a randomized, double-blind, placebo-controlled trial.

BACKGROUND: X-linked Duchenne muscular dystrophy (DMD), the most frequent human hereditary skeletal muscle myopathy, inevitably leads to progressive dilated cardiomyopathy. We assessed the effect and safety of a combined treatment with the ACE-inhibitor enalapril and the ß-blocker metoprolol in a German cohort of infantile and juvenile DMD patients with preserved left ventricular function. METHODS TRIAL DESIGN: Sixteen weeks single-arm open run-in therapy with enalapril and metoprolol followed by a two-arm 1:1 randomized double-blind placebo-controlled treatment in a multicenter setting. INCLUSION CRITERIA: DMD boys aged 10-14 years with left ventricular fractional shortening [LV-FS] ≥ 30% in echocardiography. Primary endpoint: time from randomization to first occurrence of LV-FS < 28%. Secondary: changes of a) LV-FS from baseline, b) blood pressure, c), heart rate and autonomic function in ECG and Holter-ECG, e) cardiac biomarkers and neurohumeral serum parameters, f) quality of life, and g) adverse events. RESULTS: From 3/2010 to 12/2013, 38 patients from 10 sites were centrally randomized after run-in, with 21 patients continuing enalapril and metoprolol medication and 17 patients receiving placebo. Until end of study 12/2015, LV-FS < 28% was reached in 6/21 versus 7/17 patients. Cox regression adjusted for LV-FS after run-in showed a statistically non-significant benefit for medication over placebo (hazard ratio: 0.38; 95% confidence interval: 0.12 to 1.22; p = 0.10). Analysis of secondary outcome measures revealed a time-dependent deterioration of LV-FS with no statistically significant differences between the two study arms. Blood pressure, maximal heart rate and mean-NN values were significantly lower at the end of open run-in treatment compared to baseline. Outcome analysis 19 months after randomization displayed significantly lower maximum heart rate and higher noradrenalin and renin values in the intervention group. No difference between treatments was seen for quality of life. As a single, yet important adverse event, the reversible deterioration of walking abilities of one DMD patient during the run-in period was observed. CONCLUSIONS: Our analysis of enalapril and metoprolol treatment in DMD patients with preserved left ventricular function is suggestive to delay the progression of the intrinsic cardiomyopathy to left ventricular failure, but did not reach statistical significance, probably due to insufficient sample size. CLINICAL TRIAL REGISTRATION: DRKS-number 00000115, EudraCT-number 2009-009871-36.

In Vitro Grown Micro-Tissues for Cardiac Cell Replacement Therapy in Vivo.

BACKGROUND/AIMS: Different approaches have been considered to improve heart reconstructive medicine and direct delivery of pluripotent stem cell-derived cardiomyocytes (PSC-CMs) appears to be highly promising in this context. However, low cell persistence post-transplantation remains a bottleneck hindering the approach. Here, we present a novel strategy to overcome the low engraftment of PSC-CMs during the early post-transplantation phase into the myocardium of both healthy and cryoinjured syngeneic mice. METHODS: Adult murine bone marrow mesenchymal stem cells (MSCs) and PSC-CMs were co-cultured on thermo-responsive polymers and later detached through temperature reduction, resulting in the protease-free generation of cell clusters (micro-tissues) composed of both cells types. Micro-tissues were transplanted into healthy and cryo-injured murine hearts. Short term cell retention was quantified by real-time-PCR. Longitudinal cell tracking was performed by bioluminescence imaging for four weeks. Transplanted cells were further detected by immunofluorescence staining of tissue sections. RESULTS: We demonstrated that in vitro grown micro-tissues consisting of PSC-CMs and MSCs can increase cardiomyocyte retention by >10fold one day post-transplantation, but could not fully rescue a further cell loss between day 1 and day 2. Neutrophil infiltration into the transplanted area was detected in healthy hearts and could be attributed to the cellular implantation rather than tissue damage exerted by the transplantation cannula. Injected PSC-CMs were tracked and successfully detected for up to four weeks by bioluminescence imaging. CONCLUSION: This approach demonstrated that in vitro grown micro-tissues might contribute to the development of cardiac cell replacement therapies.

Effects of pulmonary artery banding in doxorubicin-induced left ventricular cardiomyopathy.

OBJECTIVE: Central pulmonary banding has been proposed as a novel alternative for the treatment of left ventricular dilated cardiomyopathy in children. We sought to investigate the effects of central pulmonary banding in an experimental model of doxorubicin-induced left ventricular dilated cardiomyopathy. METHODS: Four-month-old sheep (n = 28) were treated with intermittent intracoronary injections of doxorubicin (0.75 mg/kg/dose) into the left main coronary artery. A total dose of up to 2.15 mg/kg of doxorubicin was administered until signs of left ventricular dilation with functional impairment occurred by transthoracic echocardiography evaluation. Animals that survived were treated with surgical central pulmonary banding through a left anterior thoracotomy or sham surgery. Transthoracic echocardiography and pressure-volume loop measurements were used to compare left ventricular function preoperatively and 3 months later. Macroscopic and microscopic histologic examinations followed after hearts were harvested. RESULTS: Nine animals from the central pulmonary banding group and 8 animals from the sham group survived and were included in the final analysis. Both groups showed similar inflammation and fibrosis upon histologic examination consistent with the toxic myocardial effects of doxorubicin. There were no differences in the echocardiographic measurements before central pulmonary banding or sham operation. Baseline measurements before the central pulmonary banding/sham operation were considered as 100%. The central pulmonary banding group had better left ventricular ejection fraction (102.5% ± 21.6% vs 76.7% ± 11.7%, P = .01), with a tendency for smaller left ventricular end-diastolic (101.2% ± 7.4% vs 120.4% ± 10.8%, P = .18) and significantly smaller end-systolic (100.3% ± 12.9% vs 116.5 ± 9.6%, P = .02) diameter of the left ventricle in comparison with the sham animals at 3 months. The end-systolic volume (101.4% ± 31.6% vs 143.4% ± 28.6%, P = .02) was significantly lower in the central pulmonary banding group 3 months postoperatively. Fractional shortening in the long axis (118.5% ± 21.5% vs 85.2% ± 22.8%, P = .016) and short axis (122.5% ± 18% vs 80.9% ± 13.6%, P = .0005) revealed significantly higher values in the central pulmonary banding group. In the conductance catheter measurements, no significant differences were seen between the groups for the parameters of systolic and diastolic function. CONCLUSIONS: Central pulmonary artery banding in the setting of experimental toxic left ventricular dilated cardiomyopathy improved left ventricular echocardiographic function and dimensions.

Evaluation of pulmonary endothelial function in Fontan patients.

OBJECTIVES: Pulmonary endothelial dysfunction due to a loss of pulsatile pulmonary blood flow is thought to be a major contributor in the development of increased pulmonary vascular resistance (PVR) in patients with a Fontan circulation. We sought to evaluate pulmonary endothelial dysfunction by vasodilator response to acetylcholine in children and adolescents with Fontan hemodynamics. METHODS: Twenty-one Fontan patients with a median age of 10.7 years (range, 3.4-30.0 years) underwent invasive cardiac catheterization, including intra-arterial Doppler and pressure measurements in a segmental pulmonary artery. Pulmonary flow reserve (PFR) was quantified as the change of average peak velocity in response to acetylcholine infusion. Local PVR was assessed by the ratio of local pressure and blood flow velocity. RESULTS: Average peak velocity significantly increased from 16.4 ± 6.6 cm/s to 20.1 ± 6.4 cm/s (P = .002) resulting in a mean PFR of 1.28 ± 0.37. Local PVR dropped from 0.72 ± 0.32 mm Hg/cm/s to 0.57 ± 0.20 mm Hg/cm/s (n = 19; P = .01). A significant relationship was found between baseline local PVR and PFR (r = 0.73; P = .0006) as well as between PFR and the percent decrease in local PVR (r = 0.85; P < .0001). In addition, percentage decrease in local PVR correlated with New York Heart Association functional class, whereas neither PFR nor local PVR correlated with global PVR. CONCLUSIONS: The assessment of PFR and local PVR may help to evaluate adverse pulmonary vascular remodeling in Fontan patients as an adjunct to the usual catheterization protocol, particularly given the difficulties in assessing global PVR in these patients. Future research is required to study whether impaired local pulmonary endothelial function may be associated with Fontan failure.

Transcatheter left atrial decompression in patients with dilated cardiomyopathy: bridging to cardiac transplantation or recovery.

BACKGROUND: Left atrial congestion results from backward failure in dilated cardiomyopathy. We aimed to evaluate feasibility and efficacy of percutaneous atrioseptostomy to create a restrictive atrial septum defect in management of dilated cardiomyopathy.Methods and resultsFrom June 2009 to December 2016, 27 interventions comprised left atria decompressions in 22 dilated cardiomyopathy patients; 9 females; age: 24 days to 36.9 years; weight: 3-50 kg; NYHA-/Ross class IV (n=16). Mean left ventricular ejection fraction was 21.5±9.7% and brain natriuretic peptide was 2291±1992 pg/ml. Dilated cardiomyopathy was classified as chronic (n=9); acute (n=1) myocarditis; idiopathic (n=5); left ventricular non-compaction (n=4); mitochondriopathy, pacemaker induced, and arrhythmogenic (n=3). Atrioseptostomy was concomitantly performed with myocardial biopsies 6.5 days (±11.7) after admission (n=11). Trans-septal puncture was used in 18 patients; foramen ovale dilatation was done in four patients. Mean balloon size was 11 mm (range 7-14 mm); total procedure time was 133±38 minutes. No procedural complications were observed. Mean left atrial pressure decreased from 15.8±6.8 to 12.2±4.8 mmHg (p=0.005), left/right atrial pressure gradient from 9.6±5.6 to 5±3.5 mmHg; brain natriuretic peptide (n=18) decreased from 1968±1606 to 830±1083 pg/ml (p=0.01). One patient unsuitable for heart transplantation died at home despite additionally performed pulmonary artery banding and three further left atrial decompressions; five patients were bridged to transplantation, two died afterwards. Functional recovery occurred in the remaining 14 patients and in six after additional pulmonary artery banding. No patient required assist device. CONCLUSIONS: Percutaneous left atrial decompression is an age-independent, effective palliation treating patients with dilated cardiomyopathy.