Absorbable metal stents for vascular use in pediatric cardiology: progress and outlook.

The past five years have yielded impressive advancements in fully absorbable metal stent technology. The desired ultimate ability for such devices to treat a vascular stenosis without long-term device-related complications or impeding future treatment continues to evoke excitement in clinicians and engineers alike. Nowhere is the need for fully absorbable metal stents greater than in patients experiencing vascular anomalies associated with congenital heart disease (CHD). Perhaps not surprisingly, commercially available absorbable metal stents have been implanted in pediatric cardiology patients with conditions ranging from pulmonary artery and vein stenosis to coarctation of the aorta and conduit/shunt reconstructions. Despite frequent short term procedural success, device performance has missed the mark with the commercially available devices not achieving degradation benchmarks for given applications. In this review we first provide a general overview detailing the theory of absorbable metal stents, and then review recent clinical use in CHD patients since the release of current-generation absorbable metal stents around 2019. We also discuss the challenges and our center's experience associated with the use of absorbable metal stents in this pediatric population. Lastly, we present potential directions for future engineering endeavors to mitigate existing challenges.

COVID-19-Related Thrombotic and Bleeding Events in Adults With Congenital Heart Disease.

Background: Altered coagulation is a striking feature of COVID-19. Adult patients with congenital heart disease (ACHD) are prone to thromboembolic (TE) and bleeding complications. Objectives: The purpose of this study was to investigate the prevalence and risk factors for COVID-19 TE/bleeding complications in ACHD patients. Methods: COVID-19-positive ACHD patients were included between May 2020 and November 2021. TE events included ischemic cerebrovascular accident, systemic and pulmonary embolism, deep venous thrombosis, myocardial infarction, and intracardiac thrombosis. Major bleeding included cases with hemoglobin drop >2 g/dl, involvement of critical sites, or fatal bleeding. Severe infection was defined as need for intensive care unit, endotracheal intubation, renal replacement therapy, extracorporeal membrane oxygenation, or death. Patients with TE/bleeding were compared to those without events. Factors associated with TE/bleeding were determined using logistic regression. Results: Of 1,988 patients (age 32 [IQR: 25-42] years, 47% male, 59 ACHD centers), 30 (1.5%) had significant TE/bleeding: 12 TE events, 12 major bleeds, and 6 with both TE and bleeding. Patients with TE/bleeding had higher in-hospital mortality compared to the remainder cohort (33% vs 1.7%; P < 0.0001) and were in more advanced physiological stage (P = 0.032) and NYHA functional class (P = 0.01), had lower baseline oxygen saturation (P = 0.0001), and more frequently had a history of atrial arrhythmia (P < 0.0001), previous hospitalization for heart failure (P < 0.0007), and were more likely hospitalized for COVID-19 (P < 0.0001). By multivariable logistic regression, prior anticoagulation (OR: 4.92; 95% CI: 2-11.76; P = 0.0003), cardiac injury (OR: 5.34; 95% CI: 1.98-14.76; P = 0.0009), and severe COVID-19 (OR: 17.39; 95% CI: 6.67-45.32; P < 0.0001) were independently associated with increased risk of TE/bleeding complications. Conclusions: ACHD patients with TE/bleeding during COVID-19 infection have a higher in-hospital mortality from the illness. Risk of coagulation disorders is related to severe COVID-19, cardiac injury during infection, and use of anticoagulants.

In vitro performance of Lifetech IBS Angel™ (iron-based bioresorbable scaffold) stents during overdilation for use in pediatric patients.

Objectives: The objective of this study was to assess the mechanical performance of the Lifetech IBS Angel stents during overdilation as is often required in pediatric applications; including time of first fracture, foreshortening, and the type of fracturing that occurs. Materials and methods: In vitro testing was performed and repeated for each stent three times under physiologic conditions with continuous audiovisual imaging allowing for post-testing evaluations. Assessment of sheath fit was also completed. Results: A total of 47 stents on monorail system were overdilated to complete fracture after passing through either a 4 or 5 French sheath. First strut fracture occurred in 4 and 6 mm stents when they reached greater than 50% overexpansion. Larger stents could achieve at least 30% increased diameter prior to first strut fracture. No fragmentation of any of the stents was seen throughout testing. Conclusion: The IBS Angel has thin struts allowing for a lower profile with increased maneuverability and use with smaller sheaths. Embolization potential of strut fragments was not seen. Increased diameter well beyond design parameters was seen in all with acceptable foreshortening.

Transcatheter utilisation of lifetech multifunction™ occluder device for closure of perimembranous and muscular ventricular septal defects: first use in North America.

Transcatheter closure of ventricular septal defects is considered first-line therapy when anatomically appropriate but is often challenged by proximity to the conduction system in perimembranous defects, or irregular defect shape, especially residual defects that may remain post-operatively. Advancements in device design, however, have allowed for significant improvements in deployment techniques and overall safety. Here we describe the first use of the Lifetech Konar-multifunction™ occluder device in North America, and our specific use of this device to close complex post-operative muscular and a perimembranous-ventricular septal defects in the same patient.

The Safety and Efficacy of Transcatheter Pulmonary Valve Replacement Combined with Electrophysiology Procedures.

The objective of this study was to evaluate the safety and efficacy of combining transcatheter pulmonary valve replacement (TPVR) and electrophysiology (EP) procedures. A retrospective review was undertaken to identify TPVR and EP procedures that were concomitantly performed in the cardiac catheterization laboratory at University of Iowa Stead Family Children's Hospital from January 2011 to October 2019. Procedural and follow-up data were compared between patients who underwent TPVR and EP procedures in the same setting to those who received TPVR or EP procedure separately and that were similar in age and cardiac anatomy. A total of 8 patients underwent combined TPVR and EP procedures. One patient was excluded due to lack of adequate control, leaving seven study subjects (57% female; median age at time of procedure 16 years). The median follow-up time was 11.5 months (range 2-36 months). Patients who received combined TPVR and EP had shorter recovery times (combined: median 18.9 h; IQR 18.35-19.5 vs separate: median 27.98 h; IQR 21.42-39.25; p-value 0.031), shorter hospital length of stay (combined: median 27.5 h; IQR 26.47-31.4 vs separate: median 38.4 h; IQR 33.42-51.50; p-value 0.016), and a 51% reduction in total hospital charges (combined: median $171,640; IQR 135.43-219.22 vs separate: median $333,560 IQR 263.20-400.98; p-value 0.016). There were no significant differences in radiation dose or procedure time between the combined and control groups. The median radiation time for those who had the combination procedure was 30.5 min [IQR 29.6-47.9], and the median dose area product was 215 mGy [IQR 158-935]. In conclusion, combining TPVR and EP procedures is feasible, safe, and economically advantageous.

Flipping syncope: The case of an adolescent athlete with syncopal episodes ultimately diagnosed with catecholaminergic polymorphic ventricular tachycardia.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a channelopathy which can lead to fatal ventricular arrhythmias. The diagnosis can be challenging due to a wide variety of clinical presentations. In this case, we describe the unusual presentation and subsequent workup of a young patient who was ultimately diagnosed with CPVT.

Cost analysis of combining congenital cardiac catheterization and electrophysiology procedures in an outpatient setting.

BACKGROUND: Patients with congenital heart disease require multiple procedures over their lifetime. These procedures increase cost and time commitment. Previous studies in the field of medicine have shown that combining procedures is an effective method to reduce cost and time. There has been no such study to evaluate the cost and efficiency of combining pediatric cardiac procedures. OBJECTIVE: The objective of this study was to compare the cost and time commitment of combined cardiac catheterization (cath) and electrophysiology (EP) outpatient procedures against separate cath and EP procedure. METHODS: Outpatient combination procedures performed in the pediatric cardiac cath lab from 2013 to 2016 were matched to a control population of two or three similar single outpatient procedures from 2009 to 2016 for patients of similar age and cardiac anatomy. Procedure duration, recovery duration, length of stay, equipment charges, physician charges, all other hospital charges, and total admission charges were analyzed. The two groups were compared using an unpaired t-test. RESULTS: A total of 92 subjects, 32 study subjects and 60 control subjects, were included in this study. Study group procedures had a significantly shorter recovery duration (P = 0.04) and length of stay (P = 0.01). Study group procedure duration trended shorter on average but statistically insignificant (P = 0.20). The total median savings for patients undergoing combined procedures in the study group was $13,181 (interquartile range $423.8-$26710). CONCLUSIONS: Combining cath and EP outpatient procedures reduces the time commitment and provides some economic advantage.

Safety and efficacy of atrial antitachycardia pacing in congenital heart disease.

BACKGROUND: Intra-atrial reentrant tachycardia (IART) is a common sequela in the congenital heart disease (CHD) population, and it significantly increases morbidity and mortality. Atrial antitachycardia devices (ATDs) capable of atrial antitachycardia pacing (ATP) therapy have been used to manage IART in the CHD population, but there are limited data on their safety and efficacy. OBJECTIVES: To determine whether ATD implantation was associated with reduced direct current (DC) cardioversions and to compare ATP success between different CHD diagnoses and ATP programs. METHODS: A single-center retrospective chart review was performed on CHD patients with ATDs. Demographic data were collected in addition to the number of DC cardioversions required before and after ATD implantation; data on ATP efficacy and the specific ATP program utilized; and adverse events related to ATD implantation or subsequent ATP treatments. RESULTS: ATD implantation in 91 CHD patients was associated with a significant reduction in DC cardioversions (P < .01). Overall, 72% of IART episodes were successfully terminated by ATP. Patients with levo-transposition of the great arteries experienced lower rates of ATP success than the remainder of the cohort (P < .01). There was no evidence of degeneration to ventricular arrhythmia or death directly attributed to ATP. CONCLUSION: ATD implantation was associated with reduced DC cardioversion burden. Patients with levo-transposition of the great arteries may experience lower ATP efficacy than patients with other CHDs; however, a larger patient population is required to better determine subgroup efficacy. These results support the safety and efficacy of ATP in the CHD population.

Atrial Antitachycardia Pacing in Complex Congenital Heart Disease: A Case Series.

Among the congenital heart disease (CHD) population, intra-atrial reentrant tachycardia (IART) is a common sequela resulting from anatomical anomalies and surgical scars that significantly increases morbidity and mortality. Atrial antitachycardia pacing (ATP) delivered by atrial antitachycardia devices (ATDs) has been used to treat IART in the CHD population. However, there remains limited data on the safety and efficacy of ATP, as well as on comparisons of its effects amongst different CHD subtypes. The purpose of the current study is to describe the clinical history and ATP efficacy in three patients with unique forms of complex CHD. During this study, a single-center review of three patients with ATDs was performed. One patient with each of the following CHD anomalies was selected for inclusion: systemic left ventricle, systemic right ventricle, and single ventricle. Data collected included ATP success rates, medications in use, direct current (DC) cardioversions, and any complications related to the ATDs. Study findings revealed the patient with a systemic left ventricle had an ATD implanted for approximately 9.5 years, with 695 of 956 (73%) episodes successfully converted. Unsuccessfully treated episodes were generally asymptomatic and self-terminating in this patient. The patient with a systemic right ventricle had an ATD implanted for approximately 16 years, with 333 of 348 (96%) episodes being successfully converted. The patient with a single ventricle had an ATD implanted for approximately 12.5 years, with 404 of 416 (97%) episodes successfully converted. The patients with biventricular physiology were able to forgo DC cardioversion after receiving their ATDs. However, due to medical noncompliance as well as multiple episodes of IART, which presented with 1:1 conduction or low rates, the single-ventricle patient still required DC cardioversions post-ATD implantation. In conclusion, this study's findings demonstrate that, while ATP can be effective in a wide variety of CHDs, experiences can vary based on individual arrhythmia substrates, cardiac anatomy, and medical compliance. Additionally, challenges remain in IART detection in patients with especially complex CHD anatomies.

Propagation Mapping Wave Collision Correlates to the Site of Successful Ablation During Voltage Mapping in Atrioventricular Nodal Reentry Tachycardia.

Voltage mapping has been used previously for slow-pathway localization for atrioventricular nodal reentrant tachycardia (AVNRT) ablation. However, propagation mapping may be a technique to further improve the localization of the slow pathway. This retrospective study aimed to evaluate the relationship of the propagation map to both the voltage mapping and successful site of ablation in patients who underwent ablation for AVNRT. All patients ≤20 years of age who underwent voltage mapping for AVNRT were included in this study. Patients were excluded if they had congenital heart disease or inadequate voltage point density within the triangle of Koch (TK). During the study, a propagation map was evaluated from the prior voltage map, marking a "wave collision" at the site of atrial wave convergence. Patient and procedural information, the location of the wave collision, the site of successful ablation, and the appearance of the voltage map were evaluated. Ultimately, 39 patients aged from four years of age to 20 years of age were evaluated. Success was achieved in 100% of patients, with a recurrence rate of 2.8% and no long-term complications observed. The average procedure time was 127 min. Follow-up length averaged seven months post operation. Low-voltage areas, and a wave collision, were present in all patients. This wave collision was typically located within the TK. The median number of ablations required for successful outcome was two. The successful ablation lesion was typically located over a low-voltage area within 4 mm of the wave collision within the TK. In conclusion, we found in this retrospective evaluation that propagation mapping resulted in a wave collision within the TK, and that the successful ablation site in the majority of patients was near a low-voltage area within 4 mm, typically superiorly, to the wave collision within the TK.