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Mitochondrial diseases are rare and heterogeneous conditions frequently affecting the heart. They are caused by mutations in nuclear or mitochondrial DNA with maternal inheritance or de novo occurrence. We present a case of 13-year-old girl with malignant mitochondrial cardiomyopathy. First presentation of the disease is with tamponade and atrial fibrillation. Cardiac imaging shows non-specific changes of the left ventricle that cannot be explained by any cardiomyopathy: hypertrophy, dilation, hypertrabeculation. These findings raised the suspicion for mitochondrial cardiomyopathy. The patient is examined by neurologist due to multisystem character of the disease. Electromyography reveals myopathy. Serum lactate and creatine phosphokinase are elevated. Acute inflammation is excluded with endomyocardial biopsy which also discovers complex III deficiency. Genetic testing identified likely pathogenic mutation in mitochondrial DNA with maternal inheritance. Two years after initial presentation patient was referred for cardiac transplantation due to fast progression of the disease. Mitochondrial cardiomyopathies have variable clinical manifestation which impedes the diagnosis and makes impossible the creation of unified criteria. The disease often affects various organs with high oxygen demand. Multiparametric approach and multidisciplinary team are recommended to increase diagnostic accuracy.

Infective endocarditis (IE) is a rare entity in children and predominantly affects patients with congenital heart defects (CHD). Our study assesses the association between the time to diagnosis of IE and the time to surgery and outcome. The mean period from initial symptom presentation to diagnosis confirmation was 38 days (3-180 days). 12 patients (60%) had an early diagnosis (< 30 days), while in 8 cases (40%) the diagnosis was delayed (>30 days). 75% of the patients with a delayed diagnosis had received prior antibiotic therapy vs. 58% of the children with an early diagnosis. All 3 children with lethal outcomes had received prior antibiotic therapy, in two of the cases the diagnosis of IE was early, and in one case it was delayed. In conclusion, empiric antibiotic therapy is associated with a delayed diagnosis of infective endocarditis, and the longer the time to surgery the greater the risk for unfavorable patient outcome.

The fenestration in Fontan operation consists in creation of a communication between venous circulation and the pulmonary venous atrium, allowing direct passage of blood from the venous to the systemic circulation (right-to-left shunt). There is no general agreement concerning the mean pulmonary artery pressure (mPAP) level above which fenestration is indicated. There are no strict guidelines for the indications for fenestration closure as well. Here we present our data about invasive hemodynamic assessment before and after temporary closure of the fenestration in patients after Fontan operation. Our recommendations regarding comprehensive evaluation of patients with fenestrations after Fontan surgery are also presented.

There is no pumping subpulmonary ventricle in patients with univentricular hemodynamics after Fontan type physiological correction of complex congenital heart defects (CHD). Hence the blood fl ow to the lungs is passive and depends on central venous pressure (CVP) and pulmonary vascular resistance (PVR) to provide adequate fi lling of the single ventricle. The increase in PVR leads to a reduction in ventricular fi lling and cardiac output, resulting in failure of the Fontan circulation (the so-called failing Fontan). Purpose. Invasive assessment of the hemodynamic effect of sildenafi l treatment in children with single ventricle Fontan circulation. Material and Methods. Twenty-six children (12 girls, 14 boys) with completed stages of Fontan type surgery in whom a selective pulmonary vasodilator (sildenafi l) has been administered during the follow-up have been investigated. An open-label, non-randomized, prospective invasive study of the hemodynamic effect of sildenafi l treatment in patients with completed Fontan surgery stages was performed. Results. A signifi cant decrease in the cavopulmonary pressure (from 16.58 ± 1.88 mm Hg to 13.80 ± 2.20 mm Hg; p < 0.001) and the pulmonary vascular resistance (from 2.02 ± 0.72 WU to 1.42 ± 0.41 WU; p = 0.001), increase of the pulmonary/systemic blood fl ow ratio (from 0.71 ± 0.21 to 0.83 ± 0.18; p < 0.05), as well as increase in the systemic oxygen saturation (from 85.65 ± 7.48% to 90.72 ± 4.53%; p = 0.005) were found. No signifi cant difference in hemodynamic parameters related to the ventricular morphology and the type of previous palliation was found. The only exception was the pulmonary blood fl ow after sildenafi l treatment, which was signifi cantly higher in children with а previous systemic to pulmonary shunt compared to children with а previous banding (p < 0.05). Conclusion. Our study showed signifi cant benefi cial changes in the main hemodynamic parameters after sildenafi l treatment. The pharmacological modulation of the pulmonary vascular status is an important component of the treatment of patients with Fontan circulation.

Accurate imaging of the morphology in a child with a rare and complex congenital heart disease (CHD) is crucial for the surgical planning and, if possible – the minimization of operative risk. We present a case of a 3-month-old child with a rare variant of Total Anomalous Pulmonary Venous Return (TAPVR) – mixed type – which illustrates the benefi t of additional imaging modalities and techniques for the operative planning. The patient’s anomalous drainage of the pulmonary veins (PV) is as follows: left and right lower PVs drained in the coronary venous sinus, left upper PV drained via a vertical vein into the innominate vein and the right upper PV drained into the superior vena cava (SVC). Clinical fi ndings consist of heart failure (HF), pulmonary venous congestion and mild hypoxemia developing within the fi rst days after birth. Transthoracic echocardiography (TTE) demonstrates the features of TAPVR, but the modality is unable to differentiate all of the described anatomic details. Accurate morphological diagnosis is obtained via contrast Computed Tomography (CT). The. additional techniques of 3D modelling and 3D printing of a patient-specifi c model, based on the acquired CT, contributed to the planning of the surgical strategy. The patient underwent a radical operation at age of 3 months. The unique aspect of the case is the application of all possible operative techniques for correction of TAPVR – coronary sinus deroofi ng, anastomosis of a draining vessel into the left atrial appendage and Warden procedure which involves tunnelling of the right upper PVs from the SVC into the left atrium. Feedback from the surgical team shows that the additional imaging methods and the printed 3D model represent the pathology in detail that completely corresponds to the intra-operative fi ndings

Introduction. Prolonged mechanical ventilation (PMV) is a well-recognized factor as a quality metric for pediatric cardiac surgical programs. Most of the risk factors for PMV are described and analyzed. Some authors had established predictive models to detect proactively patients in risk for PMV. This study aims to develop a new predictive model, based on vasoactive-ventilation-renal (VVR) score, for PMV after congenital heart surgery (CHS) in pediatric patients. Material and Methods. Medical fi les of patients 0-18 y who underwent heart surgery in 2016 and 2017 were reviewed. Patients that met the inclusion criteria were studied. PMV was defi ned as invasive mechanical ventilation ≥ 96 h. The patients were divided in two groups according to duration of mechanical ventilation: group 1-patients with PMV, group 2-patients without PMV. The focus was set on VVR score and fl uid overload in the fi rst 48 hours after the operation. Data were presented as medians with IQR or as means ± standard deviation. A non-parametric Mann-Whitney U test, binary logistic regression test and ROC curve analysis integrated in the statistical software SPSS 24.0 were used. A value of P < 0.05 was considered signifi cant. Results. 438 patients were operated in 2016 and 2017 and 384 of them were included in the study. 80 patients (20.8%) needed PMV (group 1) and 304 (79.2%) did not need PMV (group 2). There was a statistical signifi cance between group 1 and group 2 concerning the peak VVR for the day of operation 58,25(33,48) vs. 25,65(19,8) and cumulative fl uid overload in % for the fi rst 48hours +2,54(13,29) vs. – 1,19(3,4). After combining this two factors in a predictive model, the ROC curve analysis showed AUC 0,903 (95% CI 0,863-0,944) with sensitivity of 86.25% and specifi city of 82,57%. Conclusion. Combining VVR and cumulative fl uid overload, resulted in establishment of a new reliable predictive model for PMV after CHS in pediatric patients in our Center.

Exercise capacity assessment in patients with congenital heart disease (CHD) is essential for cardiovascular adaptation and is a key parameter in quality of life assessment. In daily practice, the majority of tests are performed at rest, and some even require sedation. Cardiopulmonary exercise testing (CPET) allows the assessment of the patient's haemodynamic status during exercise and provides important information about heart rate, rhythm, ST-segment analysis, arterial pressure, and parameters such as oxygen consumption, oxygen pulse and the ratio of minute ventilation to carbon dioxide produced, which helps to describe in detail the physiology of the patient in a dynamic state. This allows for assessment of aerobic capacity and helps to distinguish the causes of its limitation - cardiovascular, pulmonary or deconditioning. Objectification of exercise capacity provides a basis for better decision-making regarding follow-up plans, exercise recommendations and future interventions. This review will discuss in detail CPET and its implementation in children with CHD.

The diagnosis of complete atrioventricular septal defect (CAVSD) relies completely on echocardiography. Different measurements can be used for the differentiation of the balanced from the unbalanced forms of the defect but each of them has limitations and cannot be applied separately. There is no established algorithm ensuring precise classifi cation of the CAVSD as balanced or unbalanced, especially in borderline forms. Based on a protocol, including measurements of a series of echocardiographic parameters used by other investigators, we have managed to identify 4 measurements which when applied in a predictive model allow for correct determination of the form of the CAVSD in 97% of the cases. These parameters are: infl ow angle right ventricle/left ventricle, left atrioventricular valve infl ow, atrioventricular valve index, and ratio between the long axes of the two ventricles.

Cardiac catheterization with direct measurements of pressure and saturation in cardiac chambers and great vessels and calculation of systemic and pulmonary blood fl ow, pulmonary and systemic resistance, and pulmonary vascular reactivity are the gold standard for assessing the hemodynamics of congenital heart malformations with a left to right shunt in both children and adults. They are the basis for determining the indications for surgical or interventional treatment. Assessment of the blood fl ow according to Fick’s principle and the resistance according to Ohm‘s law are the theoretical basis of hemodynamic calculations. The steps in assessing hemodynamics in a patient with a left-to-right shunt are presented consequently: pulmonary to systemic blood fl ow ratio, calculation of pulmonary vascular resistance (PVR) in case of pulmonary hypertension (PHy), and assessment of pulmonary vascular reactivity and their clinical signifi cance as well. Special attention is paid to the assessment of hemodynamics and indications for closure in elderly patients with atrial septal defect (ASD) and left ventricular dysfunction. The limitations and sources of errors in hemodynamic calculations are presented.

Cardiac involvement by COVID-19 in children occurs most often as a part of the multisystem infl ammatory syndrome by children (MIS-C) and rarely as an isolated fi nding; affected children are predominantly older males. We present retrospective analysis data of 10 children with myocardial involvement within COVID-19, who were admitted at the Pediatric Cardiology Department of the National Heart Hospital – Sofi a. The main clinical symptoms were fever, heart failure, and gastrointestinal complaints, and the typical laboratory constellation included pronounced leukocytosis with extreme granulocytosis, signifi cant elevation of infl ammatory markers, increased serum troponin levels, and serologic evidence of contact with SARS-CoV2. Chest X-ray showed cardiomegaly and pulmonary hypervolemia; ECG changes were diverse and included abnormal repolarization and rhythm and conduction disturbances. Echocardiography revealed left ventricular dilation with depressed contractility, and cardiac MRI demonstrated myocardial edema and necrosis. Following immunomodulatory treatment, rapid recovery was observed. However, in most cases, the MRI changes persisted 6 months after the onset of symptoms, which makes the long-term prognosis unclear. We have reviewed our results considering the recent publications in the international databases regarding cardiac involvement by COVID-19 in children.

The birth of a child with congenital heart disease (CHD) completely changes the family situation. CHD is a chronic condition that from birth to life is associated with psychological characteristics and poses many challenges. This review presents the main features of the life cycle of a family with a child with CHD. The stages of a family life cycle are 6: independent living; married couple; family with children up to school age; with children from school age to adulthood; stage of “empty nest”; late stage. Each is characterized by different psychological features. The third stage or the appearance of a child with CHD is manifested by a high level of stress and anxiety, the formation and change of parenting styles, relationships with doctors. School achievements, frequent hospitalizations, and social isolation are leading in the fourth stage. The fi fth stage sometimes does not occur. Sixth is related to health problems. The fi rst stage of independence is also very problematic and often missing. The leading factors in the second stage are heredity, professional realization, and relationships with the partner. The family with CHD follows the usual stages of the life cycle, but the psychological features are related to the presence of chronic disease. Preferred parenting styles, levels of anxiety, and self-esteem differ from those, used in families without a child with CHD. It is necessary to develop training for parents to support the adaptation and integration of the disease in the life of the family.

We present the case of a 23-year-old male diagnosed with a complex congenital heart disease (with single ventricle physiology) which necessitated many surgical interventions including total cavopulmonary connection. The patient presents with recurrent (almost daily) highly symptomatic atrial tachycardia with rapid ventricular rate and poor haemodynamic tolerance. Due to failure of antiarrhythmic drug therapy the patient was referred for catheter ablation. Atrial access was provided following transconduit puncture with a standard transseptal set. Crossing to the atrium with the transseptal introducer was not successful due to resistance from the conduit and the atrial wall. Therefore, balloon dilation of the puncture using a cutting balloon was carried out which resulted in easy crossing to the atrium with a steerable transseptal introducer. Several atrial tachyarrhythmias were induced two of which allowed mapping demonstrating a macroreentrant tachycardia dependent on the cavoannular isthmus as well as a complex fi gure-of-eight circuit involving right pulmonary veins and the right atrial appendage. Linear lesions transecting the critical isthmuses of the two circuits were delivered which rendered the patient noninducible. During a 9-month follow-up period the patient remained arrhythmia free.

Balloon pulmonary valvuloplasty (BPVP) is the procedure of choice for the treatment of isolated pulmonary valve stenosis. Complications and failure of the procedure are more common in newborns and infants. Aim: To establish the effectiveness and safety of BPVP in newborns and infants. Material and methods: Ninety-one infants (11 newborns) with isolated pulmonary valve stenosis and mean age 171 ± 115 days were catheterized for BPVP between October 1986 and December 2016. BPVP was performed in 86 infants with a balloon catheter size 127±16% from the annulus dimension. The effectiveness (gradient right ventricle (RV) – pulmonary artery (PA) ≤ 35 mm Hg) and safety (lack of life–threatening complications, emergency surgery or death) of the procedure were assessed. Results: Transvalvular pressure gradient decreased from 82 ± 29 mm Hg to 29 ± 24 mm Hg (р = 0,0001) and RV pressure - from 101 ± 28 mm Hg to 52 ± 24 mm Hg (p = 0,0001). BPVP was effective in 61 infants (70,9%), mainly in those with lower initial gradient, RV pressure and less signifi cant infundibular obstruction. There were no children with hemodynamically signifi cant postprocedural pulmonary insuffi ciency. Complications were observed in 16 of the infants catheterized for BPVP (17,6%). In 5 of the children (5,5%), minor (transient) complications arose and were overcome by conservative means. Major complications were observed in 11 infants (12,1%): rhythm and conductive disorders (critical bradycardia, supraventricular/ventricular tachycardia, complete atrioventricular block) in 6 children, hemopericardium or severe right ventricular outfl ow tract rupture – in 5. The evolution was favorable after intensive treatment in 6 children with major complications, two children were sent for emergency surgery (2,2%) and death occurred in 3 of the children associated with the procedure (3,3%). The procedure was interrupted and BPVP was not performed in fi ve of the catheterized children (5,5%), all with severely dysplastic valve. Conclusion: BPVP is effective and comparatively safe procedure under the age of 1 year. Newborns, children with severely dysplastic valve and suprasystemic RV pressure are the most at-risk.

Unbalanced atrioventricular septal defect is seen by 10-15% of the patients with this congenital heart disease and poses serious challenges for the treating physicians regarding the choice of the most suitable operative intervention. The forms with moderate degree of unbalance between the two ventricles, especially when the size of the left ventricle is considered borderline, make the choice between two-ventricle correction and single-ventricle palliation quite difficult. The most important factor when judging the degree of unbalance is not the size of the ventricles but rather the redistribution of blood flow. The use of different echocardiographic measurements could contribute to the more precise determination of the indications for one of the two surgical strategies with resulting improvement of patient outcome.

The aim of this study was to determine the informative value and clinical significance of the ratio of low-density lipoprotein cholesterol to apolipoprotein-B (LDL-C/apoB) in the overall evaluation of blood lipid profile atherogenicity. Material and methods. A total of 157 apparently healthy men with normolipidemia were included in the study. The plasma levels of total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), apoA-I, apoB and apoE were measured on the Powerwave 200 automated spectrophotometer (USA) with commercially available kits (Chronolab Systems, Spain). Several clinical ratios and indices of lipid metabolism were calculated. Results. The use of apoB content in low-density lipoproteins (LDL) instead of total apoB level in plasma is preferable in calculating the LDL-C/apoB ratio. Low values of the LDL-C/LDL-apoB ratio, indicating a predominance of small dense LDL particles in plasma, were associated with higher triglycerides levels and lower apoE levels. This finding indicates that apoE, being a metabolically active apolipoprotein and regulating residence of triglycerides-rich lipoproteins in plasma, can affect size of the LDL particles. Conclusion. Thus, presence of small, dense LDL particles in plasma of men with normolipidemia can be a consequence of disturbances in catabolism and metabolic turnover of lipoproteins.

To investigate the levels of uric acid and apoE in patients with normo- and hyperlipidemia. The serum lipids, apolipoproteins and uric acid levels were measured with Chronolab (Switzerland) kits in 78 patients: 53 patients with normolipidemia and 25 patients with hyperlipidemia of type IIa and IIb. Significantly higher levels of apo-E were registered in patients with hyperlipidemia than in patients with normolipidemia, but there were no differences in content of uric acid. A comparative correlation analysis detected a significant correlation between uric acid and apoE levels in both groups but in normolipidemic patients the correlation was positive while in hyperlipidemic patients it was negative. Hyperlipidemia provokes inversion of correlation between the levels of uric acid, apoE and apoC3. A rise of apoC3 may serve an adaptive mechanism of inhibition of apo-E induced hyperlipidemia.

Apolipoprotein E (ApoE) polymorphism influences lipid metabolism, but its association with essential hypertension (EH) is controversial. The objective of this study was to examine the association between ApoE polymorphisms and EH in Bulgarian population. We carried out a case-control association study involving 490 healthy Bulgarian individuals and 211 Bulgarian patients with EH (average of three measurements ≥140 mmHg in systolic and/or ≥90 mmHg in diastolic blood pressure). Genomic DNA was extracted from venous blood using Chemagic Magnetic Separation Module I according to manufacturer’s protocol. DNA samples were then amplified by real time polymerase chain reaction (real-time PCR), followed by High Resolution Melting Analysis (HRMA) on RotorGene 6000. Hardy-Weinberg equilibrium expectation was tested by using a chi-square (χ2) goodness-of-fit test. Non-adjusted analysis of the association between ApoE genotypes and alleles with essential hypertension was based on Fisher Exact Probability Test by using the Vassarstat calculator. As found in most European populations, the ɛ3ɛ3 genotype was the most common (72.04%), followed by ɛ3ɛ4 (14.69%), ɛ2ɛ3 (9.80%), ɛ2ɛ4 (2.24%), ɛ2ɛ2 (0.82%), and ɛ4ɛ4 (0.41%) in control group. The genotype frequencies in hypertensive patients were: ɛ3ɛ3 (72.99%), ɛ3ɛ4 (16.11%), ɛ2ɛ3 (7.11%), ɛ2ɛ4 (2.37%), ɛ4ɛ4 (1.42%), ɛ2ɛ2 (0.00%). Allele frequencies were within the Hardy-Weinberg equilibrium expectations (P > 0.05) in both patients and controls. Neither the ɛ2 nor the ɛ4 carrier status was associated with hypertension (OR = 0.68, 95%CI = 0.41–1.13, p=0.14 and 1.23, 0.84–1.79, p=0.29 respectively). This study provides epidemiologic evidence that the ApoE genotype is not associated with EH in Bulgarian population.