Background Short-term improvements in quality of life (QOL) have been reported in adult congenital heart disease patients with systemic right ventricle (sRV) failure after treatment with sacubitril/valsartan. This study aimed to evaluate the medium-term QOL changes in sRV failure patients treated with sacubitril/valsartan.Methods In this single-centre, prospective cohort study, patients with symptomatic sRV failure completed the Netherlands Organisation for Applied Scientific Research/Academic Hospital Leiden Questionnaire for Adult’s Health-Related Quality of Life (TAAQOL) at baseline and after starting treatment with sacubitril/valsartan. The TAAQOL was taken at structured outpatient follow-up moments after 6, 12, 24 and 36 months of treatment. Linear mixed effects models were used to evaluate the medium-term changes in 12 QOL domains.Results Of 40 sRV failure patients initiated on sacubitril/valsartan, 35 completed the titration phase, and 31 filled in a total of 98 TAAQOL questionnaires (response rate 77.5%). Significant improvements in gross motoric functioning (p=0.008), cognitive function (p=0.002), sleep (p=0.041), social functioning (p<0.001) and daily activities (p=0.001) were observed during follow-up. No significant changes were observed in fine motoric functioning, pain, sexuality, vitality, positive, depressive or aggressive emotions. Of interest, periods with restrictions relating to the COVID-19 pandemic did not significantly influence changes over time in any of the 12 QOL domains.Conclusions Sacubitril/valsartan treatment was associated with persistent medium-term QOL improvements in gross motoric functioning, cognitive function, sleep, social functioning and daily activities domains in sRV failure patients. Self-perceived QOL of sRV failure patients may be amenable to improvement with sacubitril/valsartan.

Ablation of sites displaying Purkinje activity is highly effective against idiopathic ventricular fibrillation which often originates in the right ventricular outflow tract. However, during endocardial mapping Purkinje potentials are rarely, if never, detected in the right ventricular outflow tract. In the present study, we aimed to determine whether the Purkinje system extends into the right ventricular outflow tract. Hearts of five female sheep were blood-perfused in a Langendorff setup in which we performed epicardial and endocardial voltage mapping. During atrial pacing, the right ventricular outflow tract epicardium activated later than the epicardium of the left and right ventricular free walls. Endocardial mapping revealed Purkinje spikes at several sites in the free wall of the right ventricular outflow tract. In one heart, Purkinje spikes preceded ventricular premature beats during mapping, but were not visible during sinus rhythm. Subsequent immuno-histological examination showed a network of Connexin 40-positive Purkinje fibers across and within the wall of the right ventricular outflow tract. Quantitative analysis revealed that the transmural Purkinje fiber network was more abundant near the endocardium than epicardium. In conclusion, the Purkinje system extends into the right ventricular outflow tract of the sheep heart. These findings demonstrate that the sheep could be a valuable model for studying Purkinje-related arrhythmias in the right ventricular outflow tract.

AIMS:A striking aspect of epidermolysis bullosa patients with a mutation in KLHL24 (KLHL24mut) is their life-threatening deterioration of heart function. KLHL24 is a component of the ubiquitin-proteasome system and acts as a substrate-specific adaptor protein for E3 ubiquitin ligase. KLHL24mut is thought to represent a gain-of-function mutation, with associated cardiac and skin pathologies arising from the excessive degradation of its target proteins. Although reduced desmin levels in cardiomyocytes (CMs) have already been documented, the potential involvement of additional mechanisms in KLHL24mut -driven heart pathology remains unexplored. METHODS AND RESULTS:We report on two patients with KLHL24mut who recently manifested heart failure. To gain insights into their physiopathology, we integrated clinical data with proteomic analyses of heart tissue as well as human induced pluripotent stem cell (hiPSC) models carrying KLHL24mut. Mass spectrometry analysis of CMs differentiated from patient-derived hiPSCs mirrored the proteomic profile of their corresponding left ventricle tissue samples. KLHL24mut resulted in a reduction of several intermediate filaments (IF), mitochondrial and muscle fibre proteins as well as the emergence of an early fibrotic signature. By utilising various hiPSC-derived cardiac models along with flow cytometry, immunofluorescence, and western blot analyses, we confirmed that the excessive proteasomal activity of endogenous KLHL24mut caused a decrease in levels of desmin, synemin and vimentin, IF proteins of CMs and cardiac fibroblasts. Moreover, KLHL24mut led to mitochondrial mislocalization and increased mitophagy, reduced PKA activity, and sarcomere shortening in CMs. CONCLUSION:The deterioration of heart function in patients with KLHL24mut is driven by excessive proteasome-dependent degradation of multiple IF proteins across various cardiac cell types. Monotypic hiPSC-derived CMs and end-stage patient-derived cardiac explants from patients exhibit similar features, uncovering early pathological mechanisms and identifying a list of potential novel KLHL24mut target proteins. Finally, our findings validate that hiPSC-derived CMs represent a relevant model for future studies.

BACKGROUND:Previous research on congenital aortic stenosis (AS) mainly focused on children, while data on long-term outcomes in adults is scarce. Therefore, this study aims to evaluate outcomes in adult patients with congenital AS and identify prognostic markers for aortic valve replacement (AVR). METHODS:In this multicentre study, patients aged 18-55 years with congenital AS (peak velocity ≥2.5 m/s) registered in the Dutch CONCOR (Congential Cor Vitia) registry from expert centres for congenital heart disease between 2001 and 2019 were included. Exclusion criteria were severe aortic regurgitation (AR) or prior AVR. Associations with the composite endpoint of all-cause mortality and AVR were assessed with multivariable Cox regression. RESULTS:Of the 427 included patients (median age 26 years, 62.5% male) median aortic peak velocity was 3.1 (IQR 2.7-3.6) m/s, 35% had moderate AR and 29% showed signs of left ventricular (LV) remodelling. During a median follow-up period of 7.9 (IQR 4.1-12.6) years, 7 patients died (1.6%) and 177 patients underwent AVR (41.5%). LV systolic dysfunction was the primary indication for AVR in three patients (1.7%). Peak velocity at baseline (HR 3.17, 95% CI 2.29 to 4.39), non-sinus rhythm (HR 3.12, 95% CI 1.62 to 6.02) and concentric LV geometry (HR 1.64, 95% CI 1.04 to 2.58) were associated with the primary endpoint beside age. Significant male-female differences were observed in prognostic factors for the primary endpoint. CONCLUSION:AVR was often indicated in adult patients with congenital AS, even if the stenosis at baseline was mild. Moreover, monitoring LV remodelling alongside severity of AS is more important than focusing on systolic LV dysfunction.

Prenatal development of autonomic innervation of sinus venosus-related structures might be related to atrial arrhythmias later in life. Most of the pioneering studies providing embryological background are conducted in animal models. To date, a detailed comparison with the human cardiac autonomic nervous system (cANS) is lacking. The aim of this study was to compare the morphological and functional development of the cANS between mouse and human, specifically aimed at the venous pole. Wildtype mouse embryos (E9.5–E18.5) and healthy human fetuses (6–38 weeks gestational age (WGA)) were studied at sequential stages to obtain a comparative developmental series. Cardiac autonomic function was assessed through heart rate variability (HRV) analysis using ultrasound. Morphological assessment of the venous pole was performed using immunohistochemical stainings for neural crest cells and autonomic nerve markers. Murine cANS function did not definitively establish in utero as HRV parameters depicted no trend prior to birth. In contrast, human HRV parameters greatly increased from 20 to 30 WGA, indicating that human cANS function is established prenatally around 20 WGA and matures thereafter. Morphologically, cANS development followed a similar sequence with neural crest-derived nerves entering the venous pole in proximity to the developing pulmonary vein in both species. However, the timing of differentiation into sympathetic or parasympathetic phenotype was markedly distinct, as human autonomic markers emerged relatively later when related to major cardiogenesis. Structures related to arrhythmogenicity in humans, such as the ligament/vein of Marshall and the myocardium surrounding the pulmonary veins, become highly innervated during embryonic development in both mice and humans. Although early morphological cANS development at sinus venosus-related structures follows a similar sequence in mice and humans, there are substantial differences in the timing of functional establishment and differentiation in sympathetic and parasympathetic phenotypes, which should be taken into account when extrapolating mouse studies of the cANS to humans. The abundant innervation of sinus venosus-related structures may play a modulatory role in arrhythmogenesis under pathological conditions.

Background Systemic right ventricle (sRV) patients are at an increased risk of developing heart failure. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) could be a valuable treatment option. This study investigated the changes in ventricular function in sRV failure patients in the first year after starting SGLT2i.Methods Adult sRV patients from the international, real-world ACHIEVE-SGLT2i registry were included if they had a clinical diagnosis of sRV failure, a transthoracic echocardiogram before starting SGLT2i, and at least one in the first year after starting available for analysis. The primary outcomes were changes in sRV global longitudinal strain (GLS) and fractional area change (FAC). Longitudinal changes were evaluated using linear mixed models.Results Thirty-nine sRV failure patients (46±9.3 years old, 41% female) were included. Twenty-five (64%) had transposition of the great arteries after an atrial switch procedure and 14 (36%) had congenitally corrected transposition. sRV GLS improved significantly in the first 50 days (−1.4%-point per month, p<0.001) and stabilised afterwards (<0.1%-point per month, p=0.520). Though age had a significant overall negative effect on sRV GLS (0.1%-point per year of age, p=0.049), it did not influence the longitudinal changes after starting SGLT2i. sRV FAC also improved in the first 50 days (3.2%-point per month, p=0.002), after which sRV FAC deteriorated in patients with subpulmonary left ventricular pacing (−0.9%-point per month, p=0.012) while it stabilised in patients without pacing (0.1%-point per month, p=0.573). In the first 50 days, tricuspid annular plane systolic excursion also improved significantly in all patients (1.2 mm per month, p=0.006), and stabilised afterwards (p=0.721).Conclusions SGLT2i therapy is associated with improvements in systolic ventricular function in sRV failure patients. Despite early improvement in sRV FAC, there was a negative longer term correlation with subpulmonary left ventricular pacing, potentially reflecting adverse effects of subpulmonary ventricular pacing on sRV function.

During cardiac development, the heart is innervated by the autonomous nervous system. After development, neurons of the autonomic nervous system have limited capacity for growth and regeneration. However, in recent decades, it has become clear that cardiac nerves can regenerate after cardiac damage. Excessive reinnervation, so-called sympathetic hyperinnervation, may render patients vulnerable to ventricular arrhythmias and heart failure. Several studies have investigated axonal guidance cues as mediators of cardiac innervation. Axonal guidance cues direct neuronal growth of the axon and play a significant role in the regeneration and remodelling of cardiac autonomic innervation after cardiac damage. This review focusses on the current literature regarding the axonal guidance cue group of semaphorins and their function in the healthy and diseased postnatal heart. In view of cardiac innervation, most studies have focussed on semaphorin 3A (SEMA3A), whereas less is known about the function of the other semaphorin classes. SEMA3A is a neuronal repellent and is associated with a decrease in the density of sympathetic neurons in the heart. Its decline in expression after myocardial infarction plays a role in the development of sympathetic hyperinnervation and the subsequent increased risk of ventricular arrhythmias. In congestive heart failure, the opposite occurs: an increase in SEMA3A expression underlies decreased nerve density that may also serve as a substrate for ventricular arrhythmias. Although the literature on their role in cardiac innervation is still relatively scarce, semaphorins, especially SEMA3A, seem worthwhile to consider when exploring options to modulate pathologic innervation patterns in cardiovascular disease.

Background Cardiac arrhythmias are frequently encountered in patients with single ventricle physiology palliated by the Fontan circulation. Autonomic dysfunction, an imbalance between sympathetic and parasympathetic systems, is critical in arrhythmogenesis. The relationship between impaired autonomic function, cardiac morphology, ventricular function, and clinical outcomes in adult patients remains poorly defined. This study aims to evaluate cardiac autonomic function using heart rate variability and exercise testing and investigate autonomic factors associated with the prevalence of atrial arrhythmias in adult Fontan patients. Methods Consecutive adult Fontan patients were included in this single-centre, cross-sectional study. Cardiac autonomic function was assessed using 24-hour ambulatory electrocardiogram recordings and exercise testing. Factors associated with atrial arrhythmias were evaluated. Results Fifty-four patients (median age 22 years, 56% female) were included. Paroxysmal atrial arrhythmias were present in 26% of patients and associated with significantly lower heart rate reserve (60 vs 91 beats per minute [bpm], P = 0.004) and chronotropic index (0.46 vs 0.82, P = 0.006) during exercise testing. Independent of β-blocker use, the autonomic function parameters, standard deviation of normal-to-normal intervals and standard deviation of the average normal-to-normal intervals calculated of all 5-minute intervals, were reduced in patients with atrial arrhythmias. Ventricular arrhythmias were less frequently encountered (7%). Conclusions Atrial arrhythmias, affecting 26% of this cohort, were associated with reduced heart rate reserve and chronotropic index, partly due to β-blocker use, and decreased standard deviation of normal-to-normal intervals and standard deviation of the average normal-to-normal intervals calculated over 5-minute intervals. This suggests impaired autonomic regulation and adaptability in adult Fontan patients, potentially predisposing to late complications. Addressing autonomic dysfunction may help mitigate arrhythmic risks in this population.

BACKGROUND:In patients with nonischemic cardiomyopathy and no late gadolinium enhancement (LGE) on cardiac magnetic resonance, risk prediction for the occurrence of sustained ventricular arrhythmias (VA) is challenging. Global and regional sympathetic denervation has been associated with VA in patients with ischemic cardiomyopathy. Its prognostic relevance in nonischemic cardiomyopathy is unknown. METHODS:Consecutive patients from the Leiden Nonischemic Cardiomyopathy Study who underwent programmed electrical stimulation, LGE-cardiac magnetic resonance, and 123-iodine meta-iodobenzylguanidine imaging between 2011 and 2019 were included. The presence of LGE and global and regional sympathetic denervation on 123-iodine meta-iodobenzylguanidine were evaluated, and patients were followed for the occurrence of VA. Global denervation was assessed using the heart-to-mediastinum ratio. Regional denervation was evaluated by calculating the number of denervated segments (DS), the ratio of DS, the summed defect score, and the weighted denervation size. RESULTS:Of 75 included patients (median age 63 years [25th-75th interquartile range (IQR) 54-68], 79% male, left ventricular ejection fraction 36% [IQR, 27-44], 37% inducible for VA), 35 had no LGE. During 4.5±1.6 years of mean follow-up, VA occurred in 8 of 35 (23%) patients without LGE and in 18 of 40 (45%) patients with LGE. Among patients without LGE, those with VA had greater regional sympathetic denervation (median number of DS 8 [IQR, 7-10] versus 2 [IQR, 1-5], P=0.004; median ratio of DS 0.5 [IQR, 0.5-0.7] versus 0.2 [IQR, 0.1-0.4], P=0.007; median defect score 36 [IQR, 30-41] versus 18 [IQR, 14-24], P=0.01; median weighted denervation size 47 [IQR, 38-54] versus 22 [IQR, 14-30]; P=0.01). In bivariate analysis, the number of DS (hazard ratio, 1.25 [95% CI, 1.06-1.46]; P=0.006) was associated with the occurrence of VA in patients without LGE. Denervation of ≥7 segments identified patients without LGE at risk for VA (area under the curve, 0.83; sensitivity, 88%; specificity, 89%). Among patients with LGE, the innervation state was not associated with VA during follow-up. CONCLUSIONS:In patients with nonischemic cardiomyopathy without LGE the extent of regional denervation may contribute to risk stratification for VA.

OBJECTIVES:In selected patients with transposition of the great arteries (TGA), ventricular septal defect (VSD) and left ventricular outflow tract obstruction (LVOTO), the arterial switch operation (ASO) may be the procedure of choice. This study reviews the clinical outcomes of TGA-VSD-LVOTO patients after ASO and compares mechanisms of LVOTO in this patient group to a historical series of cardiac specimens. METHODS:This retrospective analysis included all cases with TGA-VSD-LVOTO who underwent ASO between January 1977 and December 2023. Additionally, a series of non-operated cardiac specimens with TGA-VSD-LVOTO was selected and examined for morphological comparison. RESULTS:Eleven patients with TGA-VSD-LVOTO underwent ASO. Eight of them had TGA-VSD, and three had Taussig-Bing anomaly. LVOTO mechanisms were multifactorial, including posteriorly deviated infundibular septum and fibrous tissue masses. Median age at ASO was 0.4 (0.07-1.8) years. Ten patients underwent primary LVOTO relief during ASO; no in-hospital mortality occurred. Two patients died >30 days post-ASO at 3.1 months and 6.0 years. Median follow-up was 19.0 (11.1-26.8) years, all survivors in NYHA class I. The patient without initial LVOTO relief did require reoperation during follow-up for progressive LVOTO at 3.5 months post-ASO. Two patients had moderate residual LVOTO at latest follow-up (gradient 30-50 mmHg). No significant neoaortic valve regurgitation was observed. From the anatomical specimen series, 10 of 33 TGA-VSD-LVOTO specimen were deemed eligible for ASO, revealing similar LVOTO mechanisms as the clinical cases. CONCLUSIONS:ASO is feasible in selected patients with TGA-VSD-LVOTO showing good long-term outcomes with preserved neoaortic valve function and no reoperations for LVOTO after initial relief.

Background:Single ventricle patients are at high risk of developing circulatory failure. There is limited evidence for pharmacological treatment. This study assessed the echocardiographic changes in ventricular function during sodium-glucose cotransporter 2 inhibitor (SGLT2i) therapy in patients with single ventricle failure (SVF). Methods:SVF patients with a baseline transthoracic echocardiogram within six months before starting SGLT2i and at least one echocardiographic examination within twelve months follow-up were included from a real-world international registry of adult congenital heart disease patients on SGLT2i. Mixed models were used to evaluate longitudinal changes in ventricular function and differences between patients with SVF with ≥ moderately reduced systolic function (SVFrEF) and with ≤ mildly reduced function (SVFpEF). Results:Thirteen patients were included. The median age was 21 [20-42] years, 8 (61.5 %) were female, 10 (76.9 %) had a Fontan circulation, 8 (61.5 %) had SVFrEF, and 5 (38.5 %) SVFpEF at the start of SGLT2i. The mean follow-up was 7.6 ± 3.3 months. End-systolic area decreased significantly in all patients (-1.6 cm2 per month, p = 0.007) in the first 100 days. Fractional area change improved in the first 100 days in SVFrEF patients (3.5 %-point per month, p < 0.001), while SVFpEF patients remained stable. There was a significant improvement in the free wall strain in all patients (-0.3 %-point per month, p = 0.036) but not in global longitudinal strain (p = 0.087). Isovolumic acceleration also improved in the first 100 days (0.5 m/s2 per month, p = 0.010). Conclusions:Echocardiographic signals of improved ventricular function were observed in the first year of SGLT2i therapy in patients with SVF.

Background In patients with repaired tetralogy of Fallot (rTOF) and spontaneous ventricular tachycardia (VT), transection of slow-conducting anatomical isthmus (SCAI) by ablation results in excellent long-term VT-free survival. In patients without prior VT, proactive electroanatomical mapping and preventive SCAI ablation may impact patient selection for primary prevention implantable cardioverter-defibrillator (ICD) implantation. Objectives The purpose of this study was to evaluate long-term outcomes after proactive electroanatomical mapping and ablation of SCAI and its impact on patient selection for primary prevention ICD implantation, compared with current risk stratification methods in rTOF patients without prior VT. Methods Consecutive rTOF patients without prior VT who underwent electroanatomical mapping for VT substrate identification were included (2005-2020). After successful SCAI ablation, ICD implantation was offered but was subject to shared decision making. The potential eligibility for ICD implantation was retrospectively determined using the following: 1) a clinical risk score; 2) guideline-recommended risk factors (American Heart Association [AHA] 2018 guidelines without late gadolinium enhancement [LGE] on cardiac magnetic resonance [CMR] information, AHA 2018 guidelines with LGE-CMR information, European Society of Cardiology [ESC] 2022 guidelines); and 3) electroanatomical mapping and SCAI ablation results. In the latter, patients with a nontransected SCAI, VT substrates remote from anatomical isthmuses, or severe right-/left ventricular dysfunction qualified for ICDs. Results A total of 97 patients were included (age 35 ± 16 years, 57 men); 33 patients (34%) had SCAI and 19 (20%) had inducible monomorphic VT (17 of 19 SCAI-dependent VT). Successful SCAI transection was achieved in 87% (26 of 30 patients) in whom attempted, without complications. In total, 13 patients received an ICD implantation. During a median follow-up of 58 months (Q1-Q3: 30-99 months), 4 patients (4%) had VT, all after ablation failure. According to clinical risk score, AHA 2018 guidelines without LGE-CMR information, AHA 2018 guidelines with LGE-CMR information, and ESC 2022 guidelines, 49 (51%), 24 (25%), 31 (32%), and 48 patients (49%) would have qualified for ICDs, respectively. After proactive mapping and preventive ablation, 11 patients (11%) remained ICD candidates, including all 4 with a VT event during the follow-up (annual VT risk 7%/y). Conclusions Long-term outcome of rTOF patients without SCAI is excellent. Proactive electroanatomical mapping and preventive SCAI ablation may significantly reduce primary prevention ICD implantation rates compared with current risk prediction methods.

Background:The diagnosis and management of atrioventricular (AV)-conduction disorders in patients with a Fontan circulation can be challenging. Little is known about the effects of various pacing strategies in single-ventricle patients. Here we report 1) the feasibility of transesophageal electrophysiological study (EPS) to assess AV-conduction in a patient with limited venous access and 2) the potential of echocardiography to guide epicardial systemic right ventricular (sRV) lead positioning and to evaluate the hemodynamic consequences of sRV pacing in order to mitigate long-term effects of single site ventricular pacing. Material and methods:A 21-year old male with hypoplastic left heart syndrome, palliated with Norwood and Glenn procedures, and ultimately extracardiac total cavopulmonary connection was seen for a regular check-up. He reported difficulty cycling against the wind. During exercise stress test, a 2:1 AV-block occurred at atrial frequencies >100 bpm with recovery of 1:1 AV-conduction at sinus rates of 80-100 bpm. In order to discriminate between a 2:1 conducted atrial tachycardia and an impaired anterograde AV-conduction during sinus rhythm in the setting of bilateral femoral vein and unilateral subclavian/jugular vein occlusion, EPS by transesophageal pacing was proposed. Results:Bipolar transesophageal pacing of the left atrium confirmed an anterograde AV-Wenckebach point at 103 bpm, confirming the indication for AV-sequential pacing. Epicardial leads were surgically placed on the atrium and sRV apex. During intraoperative sRV pacing, transesophageal echocardiography confirmed the ventricular contraction pattern to remain synchronous with stable estimated cardiac output. Transthoracic echocardiography was performed postoperatively to assess the effects of sRV pacing on ventricular (dys)synchrony, systolic function and estimated cardiac output. These parameters remained unchanged during sRV pacing, compared to intrinsic conduction, an important finding in light of preserving sRV function. Conclusions:EPS to assess AV conduction could safely be performed by transesophageal pacing in this patient with Fontan circulation. Moreover, echocardiographic guidance of epicardial sRV pacemaker lead placement was feasible and may help to define the optimal pacing site in Fontan patients.

Human autonomic neuronal cell models are emerging as tools for modeling diseases such as cardiac arrhythmias. In this systematic review, we compared 33 articles applying 14 different protocols to generate sympathetic neurons and 3 different procedures to produce parasympathetic neurons. All methods involved the differentiation of human pluripotent stem cells, and none employed permanent or reversible cell immortalization. Almost all protocols were reproduced in multiple pluripotent stem cell lines, and over half showed evidence of neural firing capacity. Common limitations in the field are a lack of three-dimensional models and models that include multiple cell types. Sympathetic neuron differentiation protocols largely mirrored embryonic development, with the notable absence of migration, axon extension, and target-specificity cues. Parasympathetic neuron differentiation protocols may be improved by including several embryonic cues promoting cell survival, cell maturation, or ion channel expression. Moreover, additional markers to define parasympathetic neurons in vitro may support the validity of these protocols. Nonetheless, four sympathetic neuron differentiation protocols and one parasympathetic neuron differentiation protocol reported more than two-thirds of cells expressing autonomic neuron markers. Altogether, these protocols promise to open new research avenues of human autonomic neuron development and disease modeling.

The right ventricular outflow tract (RVOT) is the predominant site of origin of idiopathic ventricular tachycardia. Idiopathic ventricular tachycardias are usually adrenergically mediated and typically sensitive to adenosine, consistent with abnormal calcium-based delayed afterdepolarizations. Whether calcium handling in the RVOT is different from the remainder of the heart is unclear.

Abstract Introduction Diagnostic work-up of patients with an anomalous aortic origin of a coronary artery (AAOCA) includes an anatomical and functional assessment. The approach to functional evaluation currently varies widely and mainly includes noninvasive assessment. Intracoronary hemodynamic assessment can potentially enhance risk assessment for myocardial ischemia and sudden cardiac death and guide management of AAOCA patients. Hence, this study aims to evaluate invasive detection of ischemia on top of the standard of care diagnostic work-up for interarterial or intraseptal AAOCA and the impact on patient management. We report the first clinical outcomes. Methods In this multicenter prospective cohort study on AAOCA, all consecutive patients of 16 years and older with AAOCA with a newly diagnosed interarterial or intraseptal course in whom diagnostic work-up according to the protocol of the MuSCAT trial was performed between January 2021 and January 2024, were included for analysis. Exclusion comprised incomplete diagnostic evaluation, hemodynamically significant concomitant congenital heart disease or obstructive coronary artery disease in the AAOCA effluence. The work-up included invasive ischemia testing using fractional flow reserve (FFR) and or instantaneous wave-free ratio (iFR)/resting full-cycle ratio (RFR) at baseline and during pharmacological stress using adenosine, adrenaline and dobutamine. Results Fifty-eight patients (50% female, median age at AAOCA diagnosis 51.5 years (IQR 44.0-59.0)) were included, Table 1. The right coronary artery was anomalous in 88%, 93% patients had an interarterial and 69% an intramural course. Non-invasive ischemia detection was positive in 12%, negative in 84% and inconclusive in 4%. Invasive hemodynamic assessment was positive for ischemia in 22%, negative in 74% and inconclusive in 3%. Class of recommendation for surgery based on ESC guidelines was I or IIa in 28% patients and IIb, III or unclassified in 72%. Invasive hemodynamic assessment changed the treatment decision in 24% of the patients; 50% with initially recommended surgical treatment and 14% with initially a conservative treatment adjudication, Figure 1. Median follow-up after initial diagnosis was 20 [IQR 10-28] months and in 56% of all patients who completed 6 months follow-up the initial symptoms alleviated. One (2%) patient underwent a percutaneous re-intervention of the operated AAOCA. Conclusions This national prospective study of invasive hemodynamic assessment in patients with AAOCA showed clinically significant impact on the adjustment of initial management strategy in 24% of the patients. No cardiac death of myocardial infarction in the AAOCA supply area occurred during follow-up. Analysis of the complete follow-up of the MuSCAT trial can further substantiate the role of additional invasive functional imaging in AAOCA.

The venous pole of the heart where the pulmonary veins will develop encompasses the sinus venosus and the atrium. In the fourth week of development, the sinus venosus consists of a left and a right part receiving blood from the common cardinal vein, the omphalomesenteric and umbilical veins. Asymmetrical expansion of the common atrium corresponds with a rightward shift of the connection of the sinus to the atrium. The right-sided part of the sinus venosus including its tributing cardinal veins enlarges to form the right superior and inferior vena cava that will incorporate into the right atrium. The left-sided part in human development largely obliterates and remodels to form the coronary sinus in adults. In approximately the same time window (4th-fifth weeks), a splanchnic vascular plexus surrounds the developing lung buds (putative lungs) with a twofold connection. Of note, during early developmental stages, the primary route of drainage from the pulmonary plexus is toward the systemic veins and not to the heart. After lumenization of the so-called mid-pharyngeal endothelial strand (MPES), the first anlage of the pulmonary vein, the common pulmonary vein can be observed in the dorsal mesocardium, and the primary route of drainage will gradually change toward a cardiac drainage. The splanchnic pulmonary venous connections with the systemic cardinal veins will gradually disappear during normal development. In case of absence or atresia of the MPES, the pulmonary-to-systemic connections will persist, clinically resulting in total anomalous pulmonary venous return (TAPVR). This chapter describes the developmental processes and molecular pathways underlying anomalous pulmonary venous connections.

BACKGROUND AND OBJECTIVE:The heart is under strict regulation of the autonomic nervous system, during which, in a healthy state, the effects of sympathetic and parasympathetic branches are balanced. In recent years, there has been increasing interest in pathological remodeling and outgrowth of cardiac autonomic nerves in relation to arrhythmogenesis. However, the small size of the cardiac nerves in relatively large tissues renders research using histological quantification of these nerves extremely challenging and usually relies on quantification of the nerve density in selected regions of interest only. Our aim was to develop a method to be able to quantify the histological nerve density in transmural tissue sections.METHODS:Here we describe a novel workflow that enables visualization and quantification of variable innervation types and their heterogeneity within transmural myocardial tissue sections. A custom semiautomatic workflow for the quantification of cardiac nerves involving Python, MATLAB and ImageJ is provided and described in this protocol in a stepwise and detailed manner.REPRESENTATIVE RESULTS:The results of two example tissue sections are represented in this paper. An example tissue section taken from the infarction core with a high heterogeneity value of 0.20, 63.3% normal innervation, 12.2% hyperinnervation, 3.6% hypoinnervation and 21.0% denervation. The second example tissue section taken from an area of the left ventricle remote from the infarction showed a low heterogeneity value of 0.02, 95.3% normal innervation, 3.8% hyperinnervation, 0.5% hypoinnervation and 0.5% denervation.CONCLUSIONS:This approach has the potential to be broadly applied to any research involving high-resolution imaging of nerves in large tissues.

Background Kidney disease is the most important predictor of death in patients with a Fontan circulation, yet its clinical and hemodynamic correlates have not been well established. Methods and Results A total of 53 ambulatory patients with a Fontan circulation (median age, 16.2 years, 52.8% male patients) underwent advanced cardiovascular magnetic resonance assessment, including 4‐dimensional flow imaging and computational fluid dynamics. Estimated glomerular filtration rate (eGFR) <90 mL/min per 1.73 m2 was observed in 20.8% and albumin‐to‐creatinine ratio >3 mg/mmol in 39.6%. The average eGFR decline rate was −1.83 mL/min per 1.73 m2 per year (95% CI, −2.67 to −0.99; P<0.001). Lower eGFR was associated with older age, larger body surface area at examination, longer time since Fontan procedure, and lower systemic ventricular ejection fraction. Higher albumin‐to‐creatinine ratio was associated with absence of fenestration at the Fontan operation, and older age and lower systemic ventricular ejection fraction at the assessment. Lower cross‐sectional area of the Fontan conduit indexed to flow (r=0.32, P=0.038), higher inferior vena cava–conduit velocity mismatch factor (r=−0.35, P=0.022), higher kinetic energy indexed to flow in the total cavopulmonary connection (r=−0.59, P=0.005), and higher total cavopulmonary connection resistance (r=−0.42, P=0.005 at rest; r=−0.43, P=0.004 during exercise) were all associated with lower eGFR but not with albuminuria. Conclusions Kidney dysfunction and albuminuria are common among clinically well adolescents and young adults with a Fontan circulation. Advanced cardiovascular magnetic resonance–derived metrics indicative of declining Fontan hemodynamics are associated with eGFR and might serve as targets to improve kidney health. Albuminuria might be driven by other factors that need further investigation.