Recent advances in adult congenital heart disease

A Bibliometric Analysis of High-Intensity Interval Training in Cardiac Rehabilitation

As global quality of life has improved, the risk factors for cardiovascular diseases have gradually increased in prevalence. People have consequently sought to improve their health through physical exercise. High-intensity interval training (HIIT) is a cardiac rehabilitation (CR) tool that has been of great interest for several years. However, its feasibility and safety remain controversial. This study aimed to explore hot research topics and new directions regarding the role of HIIT in CR and to describe the dynamic development of the field. We used the Web of Science Core Collection database to develop visualizations using CiteSpace software (v.6.1.R2). The number of articles published, institutional collaboration networks, author partnerships, and keyword co-occurrence and clustering were used to analyze the impact of HIIT on CR. Our results showed that Norway, Canada, and the United States were the most prominent contributors to this field. Articles by Nigam, A and Juneau, M had the highest number of citations. The Norwegian University of Science and Technology had performed the most in-depth research in this area. The European Journal of Preventive Cardiology had published the most articles. The United States had the highest number of publishing journals. Relevant issues focused on coronary artery disease, exercise capacity, heart failure, cardiorespiratory fitness, and physical activity. HIIT in heart transplantation may be at the forefront of research in this field and future studies should focus on this topic. HIIT-based CR can therefore improve the exercise capacity and quality of life of cardiovascular patients and improve patient compliance in a safe manner.

Pocket-sized echocardiography for screening structural heart disease: diagnostic accuracy and cost-effectiveness for population-based studies

BACKGROUND

The standard transthoracic echocardiography has some limitations in emergent and community-based situations. The emergence of pocket-sized ultrasound has led to influential advancements.

METHODS

In this prospective study, in the hospital-based phase, children with suspected structural heart diseases were enrolled. In the school-based phase, healthy children were randomly selected from six schools. All individuals were examined by experienced operators using both the standard and the pocket-sized echocardiography.

RESULTS

A total of 73 individuals with a mean age of 9.9 ± 3.2 years in the hospital-based cohort and 143 individuals with a mean age of 12.8 ± 2.9 years in the school-based cohort were examined. The agreements between the standard and the pocket-sized echocardiography were good or excellent for major CHDs in both cohorts (κ statistics > 0.61). Among valvular pathologies, agreements for tricuspid and pulmonary valves' regurgitation were moderate among school-based cohorts (0.56 [95% confidence interval 0.12-1] and 0.6 [95% confidence interval 0.28-0.91], respectively). The agreements for tricuspid and pulmonary valves' regurgitation were excellent (>0.9) among hospital-based population. Other values for valvular findings were good or excellent. The overall sensitivity and specificity were 87.5% (95% confidence interval 47.3-99.7) and 93.8% (95% confidence interval 85-98.3) among the hospital-based individuals, respectively, and those were 88% (95% confidence interval 77.8-94.7) and 68.4% (95% confidence interval 56.7-78.6) among the school-based individuals, respectively. The cost of examination was reduced by approximately 70% for an individual using the pocket-sized device.

CONCLUSIONS

When interpreted by experienced operators, the pocket-sized echocardiography can be used as screening tool among school-aged population.

Analysis of Copy Number Variants on Chromosome 21 in Down Syndrome-Associated Congenital Heart Defects

One in five people with Down syndrome (DS) are born with an atrioventricular septal defect (AVSD), an incidence 2000 times higher than in the euploid population. The genetic loci that contribute to this risk are poorly understood. In this study, we tested two hypotheses: (1) individuals with DS carrying chromosome 21 copy number variants (CNVs) that interrupt exons may be protected from AVSD, because these CNVs return AVSD susceptibility loci back to disomy, and (2) individuals with DS carrying chromosome 21 genes spanned by microduplications are at greater risk for AVSD because these microduplications boost the dosage of AVSD susceptibility loci beyond a tolerable threshold. We tested 198 case individuals with DS+AVSD, and 211 control individuals with DS and a normal heart, using a custom microarray with dense probes tiled on chromosome 21 for array CGH (aCGH). We found that neither an individual chromosome 21 CNV nor any individual gene intersected by a CNV was associated with AVSD in DS. Burden analyses revealed that African American controls had more bases covered by rare deletions than did African American cases. Inversely, we found that Caucasian cases had more genes intersected by rare duplications than did Caucasian controls. We also showed that previously DS+AVSD (DS and a complete AVSD)-associated common CNVs on chromosome 21 failed to replicate. This research adds to the swell of evidence indicating that DS-associated AVSD is similarly heterogeneous, as is AVSD in the euploid population.

Pathophysiology of valvular heart disease

Valvular heart disease (VHD) is caused by either damage or defect in one of the four heart valves, aortic, mitral, tricuspid or pulmonary. Defects in these valves can be congenital or acquired. Age, gender, tobacco use, hypercholesterolemia, hypertension, and type II diabetes contribute to the risk of disease. VHD is an escalating health issue with a prevalence of 2.5% in the United States alone. Considering the likely increase of the aging population worldwide, the incidence of acquired VHD is expected to increase. Technological advances are instrumental in identifying congenital heart defects in infants, thereby adding to the growing VHD population. Almost one-third of elderly individuals have echocardiographic or radiological evidence of calcific aortic valve (CAV) sclerosis, an early and subclinical form of CAV disease (CAVD). Of individuals ages >60, ~2% suffer from disease progression to its most severe form, calcific aortic stenosis. Surgical intervention is therefore required in these patients as no effective pharmacotherapies exist. Valvular calcium load and valve biomineralization are orchestrated by the concerted action of diverse cell-dependent mechanisms. Signaling pathways important in skeletal morphogenesis are also involved in the regulation of cardiac valve morphogenesis, CAVD and the pathobiology of cardiovascular calcification. CAVD usually occurs without any obvious symptoms in early stages over a long period of time and symptoms are identified at advanced stages of the disease, leading to a high rate of mortality. Aortic valve replacement is the only primary treatment of choice. Biomarkers such as asymmetric dimethylarginine, fetuin-A, calcium phosphate product, natriuretic peptides and osteopontin have been useful in improving outcomes among various disease states. This review, highlights the current understanding of the biology of VHD, with particular reference to molecular and cellular aspects of its regulation. Current clinical questions and the development of new strategies to treat various forms of VHD medically were addressed.

Etiology of valvular heart disease-genetic and developmental origins

Valvular heart disease occurs as either a congenital or acquired condition and advances in medical care have resulted in valve disease becoming increasingly prevalent. Unfortunately, treatments remain inadequate because of our limited understanding of the genetic and molecular etiology of diseases affecting the heart valves. Therefore, surgical repair or replacement remains the most effective option, which comes with additional complications and no guarantee of life-long success. Over the past decade, there have been significant advances in our understanding of cardiac valve development and, not surprisingly, mutations in these developmental genes have been identified in humans with congenital valve malformations. Concurrently, there has been a greater realization that acquired valve disease is not simply a degenerative process. Molecular investigation of acquired valve disease has identified that numerous signaling pathways critical for normal valve development are re-expressed in diseased valves. This review will discuss recent advances in our understanding of the development of the heart valves, as well as the implications of these findings on the genetics of congenital and acquired valvular heart disease.

Ventricular sympathetic innervation in patients with transposition of the great arteries after arterial switch operation and Rastelli procedure: impact of arterial dissection and coronary reimplantation

BACKGROUND

Coronary flow reserve (CFR) is reduced in patients with transposition of the great arteries (TGA) after the arterial switch operation (ASO). Dissection of the great arteries and coronary reimplantation may result in sympathetic denervation, with a negative effect on myocardial perfusion.

METHODS AND RESULTS

18 patients with TGA participated in the study; 9 had ASO (20.8±5.8 years). Controls were 9 patients after Rastelli procedure (22.1±6.8 years). Sympathetic innervation was measured by positron emission tomography using(11)C epinephrine (EPI). Left ventricular EPI-retention ranged from 6.1% to 15.9%/min. Patients undergoing more than 1 operation had significantly reduced EPI-retention (P<0.001). EPI-retention and time interval after surgery correlated significantly (r=0.81, P<0.001) and was higher in patients undergoing surgery at an earlier age (P<0.001). No significant difference could be found between patients after ASO or Rastelli repair. Aortic cross-clamp time inversely correlated with EPI-retention (r=-0.72; P<0.001).

CONCLUSIONS

The ASO procedure had a negative effect on sympathetic innervation of the myocardium, but because of reinnervation myocardial perfusion is not essentially altered by this mechanism. Heart surgery and prolonged aortic cross-clamp time have a negative effect on the norepinephrine content of cardiac sympathetic nerve terminals. Parameters such as ventricular performance and cardiopulmonary exercise capacity were unaffected by the degree of EPI-retention.

Remote monitoring leads to early recognition and treatment of critical arrhythmias in adults after atrial switch operation for transposition of the great arteries

BACKGROUND

Adults with transposition of the great arteries (TGA) after atrial switch repair have an increased risk for arrhythmia and sudden cardiac death. We analyzed whether a remote monitoring (RM) system as part of an implantable cardiac device contributes to timely recognition and improved treatment of critical arrhythmias in these patients.

METHODS AND RESULTS

All consecutive TGA patients (n=11) requiring a pacemaker or cardiac resynchronization therapy with or without implantable cardioverter defibrillator between 2008 and 2011 were included. RM-detected arrhythmia, abnormality of device integrity and reaction time from event transmission until acknowledgement via email and clinical decision making were analyzed and compared to a control group (n=21). In 10 patients (91%) 17 arrhythmias were detected, 8 patients (80%) indicated no symptoms. In the RM group time interval from transmission to acknowledgement was 2.4 days (range, 0-4.5 days). Clinical decision-making was advanced by a mean of 77.5 days (range, 10-197 days) compared with conventional follow-up and identified adaption of anti-arrhythmic medication in 8, electrical cardioversion in 2, overdrive pacing in 1 and radiofrequency ablation in 2 patients. A coronary sinus lead fracture was identified in 1 patient followed by successful replacement.

CONCLUSIONS

 RM enables early detection of tachyarrhythmia followed by optimization of medical treatment and potentially life-saving anti-tachycardic intervention in adults after atrial repair of TGA.  

Helicase-like transcription factor (Hltf) regulates G2/M transition, Wt1/Gata4/Hif-1a cardiac transcription networks, and collagen biogenesis

HLTF/Hltf regulates transcription, remodels chromatin, and coordinates DNA damage repair. Hltf is expressed in mouse brain and heart during embryonic and postnatal development. Silencing Hltf is semilethal. Seventy-four percent of congenic C57BL/6J Hltf knockout mice died, 75% within 12-24 hours of birth. Previous studies in neonatal (6-8 hour postpartum) brain revealed silencing Hltf disrupted cell cycle progression, and attenuated DNA damage repair. An RNA-Seq snapshot of neonatal heart transcriptome showed 1,536 of 20,000 total transcripts were altered (p < 0.05) - 10 up- and 1,526 downregulated. Pathway enrichment analysis with MetaCore™ showed Hltf’s regulation of the G2/M transition (p=9.726E^-15) of the cell cycle in heart is nearly identical to its role in brain. In addition, Brca1 and 12 members of the Brca1 associated genome surveillance complex are also downregulated. Activation of caspase 3 coincides with transcriptional repression of Bcl-2. Hltf loss caused downregulation of Wt1/Gata4/Hif-1a signaling cascades as well as Myh7b/miR499 transcription. Hltf-specific binding to promoters and/or regulatory regions of these genes was authenticated by ChIP-PCR. Hif-1a targets for prolyl (P4ha1, P4ha2) and lysyl (Plod2) collagen hydroxylation, PPIase enzymes (Ppid, Ppif, Ppil3) for collagen trimerization, and lysyl oxidase (Loxl2) for collagen-elastin crosslinking were downregulated. However, transcription of genes for collagens, fibronectin, Mmps and their inhibitors (Timps) was unaffected. The collective downregulation of genes whose protein products control collagen biogenesis caused disorganization of the interstitial and perivascular myocardial collagen fibrillar network as viewed with picrosirius red-staining, and authenticated with spectral imaging. Wavy collagen bundles in control hearts contrasted with collagen fibers that were thin, short and disorganized in Hltf null hearts. Collagen bundles in Hltf null hearts were tangled and fragmented. Thus, silencing Hltf during heart organogenesis compromised DNA double-strand break repair, and caused aberrant collagen biogenesis altering the structural network that transmits cardiomyocyte force into muscle contraction.

The adult with a fontan: a panacea without a cure? Review of long-term complications

The univentricular heart includes a spectrum of complex cardiac defects that are managed by staged palliative surgical procedures, ultimately resulting in a Fontan procedure. Since 1971, when it was first developed, the procedure has undergone several variations. These patients require lifelong management, including a thorough knowledge of their anatomic substrate, hemodynamic status, management of rhythm and ventricular function, together with multi-organ evaluation. As these patients enter middle age, there is increasing awareness of long-term complications and mortality. This review highlights the concept behind the staged surgical palliations, the unique single ventricle physiology and the long-term complications in this complex cohort of patients.

Survey of reoperation indications in tetralogy of fallot in Japan

BACKGROUND

Although the survival rate for repaired Tetralogy of Fallot (TOF) is dramatically improving, anatomical and functional residua and sequelae followed by arrhythmias and sudden death are still challenging issues to be resolved. Reoperation can reduce the incidence of arrhythmias and sudden death, but there is no consensus on the indications of reoperation for patients with TOF, especially in Japan.

METHODS AND RESULTS

A cross-sectional questionnaire survey of reoperation indications in patients with TOF was performed through a Japanese multicenter study. The questionnaire, which focused on the number of repaired TOF patients aged >15 years old, reoperation indications and management, was sent to the institutions belonging to Japanese Society for Adult Congenital Heart Disease. In total, 41.5% (78/188) of the institutions replied. The total number of repaired TOF patients was 4,010, and sudden cardiac death was observed in 45.236/4,010 (5.9%) experienced reoperation. Pulmonary stenosis (32%) and pulmonary regurgitation (29%) were the most common reasons for reoperation. There were only 2 implantable cardioverter defibrillator or resynchronization therapy defibrillator implantations. The physiological/anatomical indications of reoperation differed among the hospitals.

CONCLUSIONS

Approximately 1.1% of patients suffered sudden death and 6% of repaired TOF patients had reoperation. The indications of reoperation, however, varied among the institutions. Therefore, detailed information for each case of sudden death or reoperation should be collected and analyzed in order to establish guidelines for reoperation.

Echocardiographic evaluation of the single right ventricle in congenital heart disease: results of new techniques

Right ventricular (RV) function is increasingly recognized as having prognostic significance in various disease processes. The current gold standard for noninvasive measurement of RV function is cardiac magnetic resonance imaging; however, because of practical considerations, echocardiography remains the most often used modality for evaluating the RV. In the past, because of its complex morphology, echocardiographic assessment of the RV was usually qualitative in nature. Current advances in echocardiographic techniques have been able to overcome some of the previous limitations and thus quantification of RV function is increasingly being performed. In addition, recent echocardiographic guidelines for evaluating the RV have been published to aid in standardizing practice. The evaluation of RV function almost certainly has no greater importance than in the congenital heart population, especially in those patients that have a single RV acting as the systemic ventricle. As this complex population continues to increase in number, accurate and precise evaluation of RV function will be a major issue in determining clinical care.