Establishing a nationwide pediatric heart transplantation program with mid-term results comparable to worldwide data - The Czech experience.

BACKGROUND: Heart transplantation (HTx) is an established therapeutic option for children with end-stage heart failure. Comprehensive pediatric nationwide HTx program was introduced in 2014 in the Czech Republic. The aim of this study was to evaluate its mid-term characteristics and outcomes and to compare them with international data. METHODS: Retrospective observational study, including all patients who underwent HTx from June 2014 till December 2022. Data from the institutional database were used for descriptive statistics and survival analyses. RESULTS: A total of 30 HTx were performed in 29 patients with congenital heart disease (CHD, N = 15, single ventricular physiology in 10 patients) and cardiomyopathy (CMP, N = 14). Ten patients were bridged to HTx by durable left ventricular assist devices (LVADs) for a mean duration of 104 (SD 89) days. There was one early and one late death during median follow-up of 3.3 (IQR 1.3-6.1) years. Survival probability at 5 years after HTx was 93%. Two patients underwent re-transplantation (one of them in an adult center). Significant rejection-free survival at 1, 3, and 6 years after HTx was 76%, 63%, and 63%, respectively. CONCLUSIONS: The introduced pediatric HTx program reflects the complexity of the treated population, with half of the patients having complex CHD and one-third being bridged to HTx by LVADs. Mid-term results are comparable to worldwide data. The data confirm the possibility of establishing a successful nationwide pediatric HTx program in a relatively small population country with well-developed pediatric cardiovascular care and other transplantation programs.

Long-Term Results of Congenital Aortic Stenosis Treatment in the Era of Percutaneous Balloon Valvuloplasty: Up to 33 Years Follow-Up.

Background The goal of this study was to evaluate long-term results of percutaneous balloon valvuloplasty (BVPL) used exclusively for initial management of congenital aortic stenosis in children. Methods and Results A total of 409 consecutive pediatric patients (134 newborns, 275 older patients) who underwent BVPL as initial treatment of aortic stenosis in a single nationwide pediatric center were subjected to a retrospective follow-up study. The resulting follow-up time reached a median of 18.5 (interquartile range, 12.2-25.1) years. Successful BVPL was defined by residual Doppler gradient <70/40 (systolic/mean) mm Hg. The primary end point was death; secondary end points included any valve reintervention, balloon revalvuloplasty, any aortic valve surgery, and aortic valve replacement, respectively. BVPL effectively reduced the peak and mean gradient both immediately and at the latest follow-up (P<0.001). There was significant procedure-related progression of aortic insufficiency (P<0.001). Higher aortic annulus z score was predictive for severe aortic regurgitation (P<0.05) and lower z score for insufficient gradient reduction (P<0.05). The actuarial probability of survival/survival free from any valve reintervention was 89.9%/59.9%, 85.9%/35.2%, and 82.0%/26.7% at 10, 20, and 30 years after first BVPL, respectively. Left ventricular dysfunction or arterial duct dependency as the indication for BVPL was predictive of both worse survival and survival free from any reintervention (P<0.001). Lower aortic annulus z score and lower balloon-to-annulus ratio were predictive of a need for revalvuloplasty (P<0.001). Conclusions Percutaneous BVPL provides good initial palliation. In patients with hypoplastic annuli and left ventricular or mitral valve comorbidity, the results are less favorable.

Does COVID-19 pose a threat for patients after univentricular palliation? Thrombosis of the Fontan tunnel.

A 6-year-old boy, born with hypoplastic left heart syndrome, underwent total cavopulmonary connection and later presented in a significantly deteriorated condition. A CT scan revealed multiple thrombi in the extracardiac conduit, although the patient was maintained on an effective anticoagulant therapy. Further examination revealed anamnestic antibodies suggesting that the patient had gone through a clinically inapparent COVID-19 infection, which we conclude most likely contributed to his hypercoagulable state and led to the formation of significant thrombi impairing the patient's haemodynamics. The patient underwent a surgical thrombectomy; there were no post-operative thrombotic complications.

Influence of fenestration on long-term Fontan survival.

INTRODUCTION: Fenestration in the total cavopulmonary connection system may improve the outcome of patients with significant risk factors for Fontan haemodynamics. Our study aims to analyse the difference in long-term survival between non-fenestrated and fenestrated patients. METHODS: All consecutive patients (n = 351) who underwent total cavopulmonary connection between 1992 and 2016 were identified. Six early deaths were excluded resulting in a group of 345 patients. Median (interquartile range,) length of follow-up was 14.4 (7.1-19.7) years. Freedom from the composite endpoint of death, total cavopulmonary connection take-down or indication for a heart transplant was analysed. RESULTS: Fenestration was absent in 237 patients (68.7%, Group 1), was created and closed later in 79 patients (22.9%, Group 2), and remained open in 29 patients (8.4%, Group 3). Mean survival probability until composite endpoint was 97.1 and 92.9% at 10 and 20 years, respectively. Patients with patent fenestration had worse survival (p < 0.001) as compared to both the non-fenestrated and fenestration closure groups. Despite a similar outcome, exercise capacity was lower in Group 2 than 1 (p = 0.013). In 58 patients with interventional fenestration closure, Nakata index was lower at the time of closure than pre-operatively, and both the pressure in the circuit and oxygen saturation in the aorta increased significantly (p < 0.001). CONCLUSIONS: Patients with persisting risk factors preventing fenestration closure are at higher risk of reaching the composite endpoint. Patients after fenestration closure have the worse functional outcome; their survival is, however, not different from the non-fenestrated group.

Exercise capacity after total cavopulmonary anastomosis: a longitudinal paediatric and adult study.

AIMS: Fontan palliation is a surgical strategy for patients with complex congenital heart disease, in whom biventricular circulation cannot be achieved. Long-term survival is negatively affected by the absence of sub-pulmonary ventricle and increased systemic venous pressure. Exercise capacity is a known predictor of overall survival and quality of life in congenital heart defects. We aim to track individual trends of peak oxygen uptake (V̇O2 peak) after total cavopulmonary connection (TCPC), identify predictors of deterioration, and derive a disease-specific reference V̇O2 peak dataset. METHODS AND RESULTS: A retrospective study of serial cardiopulmonary exercise testing (CPET) data, gathered from all patients who underwent TCPC in the Czech Republic between 1992 and 2016. Of 354 consecutive patients with TCPC, 288 (81.4%) patients underwent one or more CPETs yielding 786 unique V̇O2 peak values used as a reference dataset. Longitudinal data were available in 206 (58.2%) patients, who underwent a median (inter-quartile range) of 3.0 (2.0-5.0) CPETs over a mean (standard deviation) of 8.9 (5.5) years. The decline of exercise capacity with age was linear and not faster than in healthy peers (P = 0.47), but relative values of V̇O2 peak in TCPC patients were 12.6 mL/min/kg lower. Single ventricular morphology and pulmonary artery size had no significant influence on the exercise capacity dynamics. V̇O2 peak decline correlated negatively with the trend of body mass index z-score (P = 0.006) and was faster in women than men (P = 0.008). CONCLUSIONS: Total cavopulmonary connection patients have significantly reduced exercise capacity. The age-related decline paralleled the healthy population and correlated negatively with the body mass index trend. The presented V̇O2 peak reference dataset may help the clinicians to grade the severity of exercise capacity impairment in individual TCPC patients.

Long-Term Survival and Freedom From Coronary Artery Reintervention After Arterial Switch Operation for Transposition of the Great Arteries: A Population-Based Nationwide Study.

Background The aim of this study was to evaluate long-term survival and freedom from coronary artery reintervention after the arterial switch operation (ASO). Methods and Results This single-center nationwide retrospective study included consecutive children who underwent ASO between 1990 and 2016 (n=605). Long-term outcomes were obtained by cross-mapping individual data with the National Death Registry and the National Registry of Cardiovascular Interventions for adults. A control group was randomly retrieved at a 1:10 ratio from the National Birth and Death Registries. Early mortality was 3.3% and late mortality was 1.7% during a median follow-up of 10 (interquartile range, 5-16) years. The probability of overall survival at 20 years after ASO was 94.9% compared with 99.5% in the background population (hazard ratio [HR] 15.6; 95% CI, 8.9-27.5, P<0.001). Independent multivariable predictors of worse survival were an intramural coronary artery (HR, 5.2; 95% CI, 1.8-15.2, P=0.002) and period of ASO 1990 to 1999 (HR, 4.6; 95% CI, 1.5-13.6, P<0.001). Fourteen patients (2.3%) required 16 coronary artery reoperations. Freedom from coronary artery reintervention at 20 years after ASO was 96%. The only independent multivariable predictor associated with a higher hazard for coronary artery reintervention was an intramural coronary artery (HR, 33.9; 95% CI, 11.8-97.5, P<0.001). Conclusions Long-term survival after ASO is excellent. Coronary artery reinterventions are rare. An intramural coronary artery was an independent predictor associated with a higher risk for coronary artery reintervention and death, regardless of the surgical period.

How many types of circulation can a boy have during his life? A case of aortic stenosis with a borderline left ventricle.

Severe aortic stenosis can be accompanied by various degrees of left ventricular underdevelopment. The assessment whether a borderline-sized left ventricle can or cannot support the systemic circulation is crucial. The decision-making still remains challenging. We present a case that illustrates that the development of haemodynamic parameters can be difficult to estimate, even in the long term. The patient went from biventricular to univentricular circulation and back and could finally be palliated by heart transplantation. Modern technology including long-term mechanical cardiac support as a bridge to candidacy and drug therapy for pulmonary hypertension were vital to successfully combat a previously lethal disease.

Prolonged repolarization in atrial septal defect: An example of mechanoelectrical feedback due to right ventricular volume overload.

BACKGROUND: Prolonged corrected QT (QTc) intervals are frequently observed in children before atrial septal defect (ASD) closure in our department. OBJECTIVE: The aim of the study was to assess the effect of long-term right ventricular volume overload on repolarization. METHODS: QRS, QT, and JT intervals were measured manually in leads II and V5 of a standard 12-lead electrocardiogram in 45 children with an isolated ASD a day before and at least 6 months after ASD closure. QT intervals were corrected for heart rate using the Bazett, Fridericia, Framingham, and Hodges formulas. Each QTc interval calculated using the Bazett formula was compared to sex- and age-matched normal values. RESULTS: Individual QTc intervals shortened significantly (P < .001) using all correction formulas, whereas the QRS duration did not change. The prevalence of prolonged QTc interval decreased from 22.2% to 2.2% after shunt closure (P = .007). CONCLUSION: The QTc interval shortens significantly after the closure of a hemodynamically relevant ASD in childhood. This phenomenon is independent of the used QT correction formula and may reflect a mechanoelectrical feedback associated with right ventricular volume overload.

Chronic hypoxia inhibits tetrahydrobiopterin-induced NO production in rat lungs.

Tetrahydrobiopterin (BH4) is an essential cofactor for nitric oxide synthases (NOS). Oxidative stress oxidises BH4 to dihydrobioptein (BH2), resulting in the uncoupling of the two enzymatic domains of NOS and the production of superoxide rather than NO (NOS uncoupling). Oxidative stress is known to be increased in the early stage of chronic hypoxia. This study investigated the participation of NOS uncoupling in the early phase of hypoxia-induced pulmonary hypertension in rats. Rats were exposed to 10% O(2) for 4 days. We investigated the effect of BH4 in vitro on isolated rat lungs and isolated rat peripheral pulmonary blood vessels and in vivo on exhaled NO concentration in exhaled air. BH4 attenuated hypoxic pulmonary vasoconstriction in isolated lungs and its effect was reversed by l-NAME (NOS inhibitor). The main finding of the study is that the effect of BH4 was smaller in rats exposed to 4 days of hypoxia than in normoxic controls. The finding was similar in isolated pulmonary blood vessels. BH4 increased exhaled NO in both normoxic and hypoxic rats. This increase was blunted by l-NIL (specific iNOS inhibitor) and therefore attributable to iNOS. We conclude that BH4 increased NO production in both normoxic and hypoxic rats. The increase was, however, smaller in hypoxic lungs than in controls. We assume that the smaller increase in NO production in hypoxic lungs is due to the decreased BH4/BH2 ratio in chronic hypoxia and NOS uncoupling resulting from this condition.

Tyrosine kinase inhibitors are potent acute pulmonary vasodilators in rats.

Tyrosine kinase inhibitors are promising for the treatment of severe pulmonary hypertension. Their therapeutic effects are postulated to be due to inhibition of cell growth-related kinases and attenuation of vascular remodeling. Their potential vasodilatory activities have not been explored. Vasorelaxant effects of the tyrosine kinase inhibitors imatinib, sorafenib, and nilotinib were examined in isolated pulmonary arterial rings from normal and pulmonary hypertensive rats. Phosphorylation of myosin light chain phosphatase and myosin light chain was assessed by Western blots. Acute hemodynamic effects of imatinib were tested in the pulmonary hypertensive rats. In normal pulmonary arteries, imatinib reversed serotonin- and U46619-induced contractions in a concentration-dependent and endothelium-independent manner. Sorafenib and nilotinib relaxed U46619-induced contraction. Imatinib inhibited activation of myosin phosphatase induced by U46619 in normal pulmonary arteries. All three tyrosine kinase inhibitors concentration-dependently and completely reversed the spontaneous contraction of hypertensive pulmonary arterial rings unmasked by inhibition of nitric oxide synthase. Acute intravenous administration of imatinib reduced high right ventricular systolic pressure in pulmonary hypertensive rats, with little effect on left ventricular systolic pressure and cardiac output. We conclude that tyrosine kinase inhibitors have potent pulmonary vasodilatory activity, which could contribute to their long-term beneficial effect against pulmonary hypertension. Vascular smooth muscle relaxation mediated via activation of myosin light chain phosphatase (Ca(2+) desensitization) appears to play a role in the imatinib-induced pulmonary vasodilation.