Incidence and effect of early postoperative ventricular arrhythmias after congenital heart surgery

Postoperative Cardiac Arrhythmias in Pediatric and Neonatal Patients with Congenital Heart Disease-A Narrative Review

Cardiac arrhythmias are a frequent complication in the evolution of patients with congenital heart disease. Corrective surgery for these malformations is an additional predisposition to the appearance of arrhythmias. Several factors related to the patient, as well as to the therapeutic management, are involved in the etiopathogenesis of cardiac arrhythmias occurring post-operatively. The risk of arrhythmias in the immediate postoperative period is correlated with the patient's young age and low weight at surgery. The change in heart geometry, hemodynamic stress, and post-surgical scars represent the main etiopathogenic factors that can contribute to the occurrence of cardiac arrhythmias in the population of patients with operated-on congenital heart malformations. Clinical manifestations differ depending on the duration of the arrhythmia, underlying structural defects, hemodynamic conditions, and comorbidities. The accurate diagnosis and the establishment of specific management options strongly influence the morbidity and mortality associated with arrhythmias. As such, identifying the risk factors for the occurrence of cardiac arrhythmias in the case of each patient is essential to establish a specific follow-up and management plan to improve the life expectancy and quality of life of children.

Special Considerations in Critical Care of the Congenital Heart Disease Patient

Outcomes of congenital heart disease have improved markedly over the past 20 years, with survival to adulthood now close to 90%. The mean age of admission to an intensive care unit (ICU) is 40 years. The incidence of hospital and critical care admissions have increased significantly as a consequence of this improved survival. Intensivists are now confronted with the management not only of complex adult congenital heart disease (ACHD) lesions from a cardiac perspective, but also of extracardiac organ consequences of years of abnormal circulation after surgical or palliative correction. Kidney and liver dysfunction and respiratory and hematologic abnormalities are very common in this population. ACHD patients can present to the ICU for a vast number of reasons, classified in this review as medical noncardiac, medical cardiac, and surgical. Community/hospital-acquired infections, cerebrovascular accidents, and respiratory failure, alongside arrhythmias and heart failure, are responsible for medical admissions. Surgical admissions include postoperative management after correction or palliation, but also medical optimisation and work-up for advanced therapies. ICU management of this large heterogeneous group requires a thorough understanding of the pathophysiology in order to apply conventional adult critical care modalities; left ventricular or right ventricular dysfunction, pulmonary hypertension, intracardiac, extracardiac, and palliative surgical shunts can be present and require additional consideration. This review focuses on the pathophysiology, long-term sequelae, and different treatment modalities to supply a framework for the ICU physician caring for these patients. Successful outcome, especially in complex lesions, depends on early involvement of specialised ACHD centres.

Impact of obesity on post-operative arrhythmias after congenital heart surgery in children and young adults

BACKGROUND

Obesity increases the risk of post-operative arrhythmias in adults undergoing cardiac surgery, but little is known regarding the impact of obesity on post-operative arrhythmias after CHD surgery.

METHODS

Patients undergoing CHD surgery from 2007 to 2019 were prospectively enrolled in the parent study. Telemetry was assessed daily, with documentation of all arrhythmias. Patients aged 2-20 years were categorised by body mass index percentile for age and sex (underweight <5, normal 5-85, overweight 85-95, and obese >95). Patients aged >20 years were categorised using absolute body mass index. We investigated the impact of body mass index category on arrhythmias using univariate and multivariate analysis.

RESULTS

There were 1250 operative cases: 12% underweight, 65% normal weight, 12% overweight, and 11% obese. Post-operative arrhythmias were observed in 38%. Body mass index was significantly higher in those with arrhythmias (18.8 versus 17.8, p = 0.003). There was a linear relationship between body mass index category and incidence of arrhythmias: underweight 33%, normal 38%, overweight 42%, and obese 45% (p = 0.017 for trend). In multivariate analysis, body mass index category was independently associated with post-operative arrhythmias (p = 0.021), with odds ratio 1.64 in obese patients as compared to normal-weight patients (p = 0.036). In addition, aortic cross-clamp time (OR 1.007, p = 0.002) and maximal vasoactive-inotropic score in the first 48 hours (OR 1.03, p = 0.04) were associated with post-operative arrhythmias.

CONCLUSION

Body mass index is independently associated with incidence of post-operative arrhythmias in children after CHD surgery.

Electrical storm after correction of an uncomplicated congenital atrial septal defect in an adult: a case report

BACKGROUND

There is a paucity of published literature describing electrical storm after the correction of uncomplicated atrial septal defect (ASD) in an adult.

CASE PRESENTATION

We present a 49-year-old woman with a congenital ASD combined with mild tricuspid regurgitation who denied any history of arrhythmia or other medical history. She suffered from electrical storm (≥ 3 episodes of ventricular tachycardias or ventricular fibrillations) in the early stage after ASD repair with combined tricuspid valvuloplasty. During electrical storm, her electrolytes were within normal ranges and no ischemic electrocardiographic changes were detected, which suggested that retained air embolism or acute coronary thrombosis were unlikely. Additionally, echocardiographic findings and her central venous pressure (5-8 mmHg during the interval between attacks) failed to support the diagnosis of pericardial tamponade. After a thorough discussion, the surgeons conducted an emergent re-exploration and repeated closure of the ASD with combined DeVega's annuloplasty. Eventually, the patient recovered uneventfully, without reoccurring arrhythmias during follow-up. Although we fail to determine the definite cause, we speculate that the causes probably are iatrogenic injury of the conduction system due to a rare anatomic variation, poor intraoperative protection, latent coronary distortion during tricuspid valvuloplasty, or idiopathic or secondary abnormalities of the conduction system.

CONCLUSIONS

For most surgeons, performing re-exploration without a known etiology is a difficult decision to make. This case illustrates that re-exploration could be an option when electrical storm occurs in the early stage postoperatively. Nevertheless, surgeons should assess the benefit-risk ratio when taking this unconventional measure.

SOX17 loss-of-function variation underlying familial congenital heart disease

As the most prevalent form of human birth defect, congenital heart disease (CHD) contributes to substantial morbidity, mortality and socioeconomic burden worldwide. Aggregating evidence has convincingly demonstrated that genetic defects exert a pivotal role in the pathogenesis of CHD, and causative mutations in multiple genes have been causally linked to CHD. Nevertheless, CHD is of pronounced genetic heterogeneity, and the genetic components underpinning CHD in the overwhelming majority of patients remain obscure. In this research, a four-generation consanguineous family suffering from CHD transmitted in an autosomal dominant mode was recruited. By whole-exome sequencing and bioinformatics analyses as well as Sanger sequencing analyses of the family members, a new heterozygous SOX17 variation, NM_022454.4: c.553G > T; p.(Glu185*), was identified to co-segregate with CHD in the family, with complete penetrance. The nonsense variation was neither detected in 310 unrelated healthy volunteers used as controls nor retrieved in such population genetics databases as the Exome Aggregation Consortium database, Genome Aggregation Database, and the Single Nucleotide Polymorphism database. Functional assays by utilizing a dual-luciferase reporter assay system unveiled that the Glu185*-mutant SOX17 protein had no transcriptional activity on its two target genes NOTCH1 and GATA4, which have been reported to cause CHD. Furthermore, the mutation abrogated the synergistic transactivation between SOX17 and NKX2.5, another established CHD-causing transcription factor. These findings firstly indicate SOX17 loss-of-function mutation predisposes to familial CHD, which adds novel insight to the molecular mechanism of CHD, implying potential implications for genetic risk appraisal and individualized prophylaxis of the family members affected with CHD.

A novel TBX5 mutation predisposes to familial cardiac septal defects and atrial fibrillation as well as bicuspid aortic valve

TBX5 has been linked to Holt-Oram syndrome, with congenital heart defect (CHD) and atrial fibrillation (AF) being two major cardiac phenotypes. However, the prevalence of a TBX5 variation in patients with CHD and AF remains obscure. In this research, by sequencing analysis of TBX5 in 178 index patients with both CHD and AF, a novel heterozygous variation, NM_000192.3: c.577G>T; p.(Gly193*), was identified in one index patient with CHD and AF as well as bicuspid aortic valve (BAV), with an allele frequency of approximately 0.28%. Genetic analysis of the proband's pedigree showed that the variation co-segregated with the diseases. The pathogenic variation was not detected in 292 unrelated healthy subjects. Functional analysis by using a dual-luciferase reporter assay system showed that the Gly193*-mutant TBX5 protein failed to transcriptionally activate its target genes MYH6 and NPPA. Moreover, the mutation nullified the synergistic transactivation between TBX5 and GATA4 as well as NKX2-5. Additionally, whole-exome sequencing analysis showed no other genes contributing to the diseases. This investigation firstly links a pathogenic variant in the TBX5 gene to familial CHD and AF as well as BAV, suggesting that CHD and AF as well as BAV share a common developmental basis in a subset of patients.