Electrocardiograms Do Not Detect Myocardial Ischemia in Patients With Williams Syndrome and Nonsyndromic Elastin Arteriopathy With Coronary Artery Stenosis.

Coronary artery stenosis (CAS) may affect up to 27% of patients with Williams syndrome (WS), which may lead to myocardial ischemia. Patients with WS face a 25- to 100-fold greater risk of sudden cardiac death, frequently linked to anesthesia. Assessing CAS requires either imaging while under general anesthesia or intraoperative assessment, with the latter considered the gold standard. Our study aimed to identify electrocardiogram (ECG) markers of myocardial ischemia in patients with WS or nonsyndromic elastin arteriopathy and documented CAS. We retrospectively reviewed patients with WS/elastin arteriopathy who underwent supravalvar aortic stenosis surgery and CAS assessment from January 1, 2006 to April 30, 2021. A pediatric electrophysiologist, not aware of the patients' CAS status, reviewed their preoperative ECGs for markers of ischemia. We assessed associations of study parameters using Wilcoxon rank-sum and Fisher's exact tests. Of 34 patients, 62% were male, with a median age of 20 months (interquartile range: 8 to 34). CAS was present in 62% (21 of 34), 76% of whom (16 of 21) were male. There were no ECG indicators of myocardial ischemia in patients with CAS. In conclusion, CAS was present in >1/2 the children with WS/elastin arteriopathy who underwent repair of supravalvar aortic stenosis. CAS in WS/nonsyndromic elastin arteriopathy does not appear to exhibit typical ECG-detectable myocardial ischemia. ECGs are not a useful screening tool for CAS in WS/elastin arteriopathy. Given the high anesthesia-related cardiac arrest risk, other noninvasive indicators of CAS are needed.

Outcomes After Development of Ventricular Arrhythmias in Single Ventricular Heart Disease Patients With Fontan Palliation.

BACKGROUND: With the advent of more intensive rhythm monitoring strategies, ventricular arrhythmias (VAs) are increasingly detected in Fontan patients. However, the prognostic implications of VA are poorly understood. We assessed the incidence of VA in Fontan patients and the implications on transplant-free survival. METHODS: Medical records of Fontan patients seen at a single center between 2002 and 2019 were reviewed to identify post-Fontan VA (nonsustained ventricular tachycardia >4 beats or sustained >30 seconds). Patients with preFontan VA were excluded. Hemodynamically unstable VA was defined as malignant VA. The primary outcome was death and heart transplantation. Death with censoring at transplant was a secondary outcome. RESULTS: Of 431 Fontan patients, transplant-free survival was 82% at 15 years post-Fontan with 64 (15%) meeting primary outcome of either death (n=16, 3.7%), at a median 4.6 (0.4-10.2) years post-Fontan, or transplant (n=48, 11%), at a median of 11.1 (5.9-16.2) years post-Fontan. Forty-eight (11%) patients were diagnosed with VA (90% nonsustained ventricular tachycardia, 10% sustained ventricular tachycardia). Malignant VA (n=9, 2.0%) was associated with younger age, worse systolic function, and valvular regurgitation. Risk for VA increased with time from Fontan, 2.4% at 10 years to 19% at 20 years. History of Stage 1 surgery with right ventricular to pulmonary artery conduit and older age at Fontan were significant risk factors for VA. VA was strongly associated with an increased risk of transplant or death (HR, 9.2 [95% CI, 4.5-18.7]; P<0.001), with a transplant-free survival of 48% at 5-year post-VA diagnosis. CONCLUSIONS: Ventricular arrhythmias occurred in 11% of Fontan patients and was highly associated with transplant or death, with a transplant-free survival of <50% at 5-year post-VA diagnosis. Risk factors for VA included older age at Fontan and history of right ventricular to pulmonary artery conduit. A diagnosis of VA in Fontan patients should prompt increased clinical surveillance.

Identifying an appropriate endpoint for cryoablation in children with atrioventricular nodal reentrant tachycardia: Is residual slow pathway conduction associated with recurrence?

BACKGROUND: Cryoablation is increasingly used to treat atrioventricular nodal reentrant tachycardia (AVNRT) due to its safety profile. However, cryoablation may have higher recurrence than radiofrequency ablation (RFA), and the optimal procedural endpoint remains undefined. OBJECTIVE: The purpose of this study was to identify the association of cryoablation procedural endpoints with postprocedural AVNRT recurrence. METHODS: We performed a single-center, retrospective analysis of pediatric patients following successful first-time cryoablation for AVNRT between January 1, 2011, and December 31, 2019. Preablation inducibility of AVNRT was recorded. Procedural endpoints, including slow pathway (SP) conduction (presence of jump or echo beats) with and without isoproterenol, were identified. Recurrence was established from clinical notes and/or direct patient contact. RESULTS: Of 256 patients, 147 (57%) were assessed on isoproterenol precryoablation, and 171 (47%) were assessed on isoproterenol postcryoablation. Mean cryolesion time was 2586 ± 1434 seconds. Following ablation, 104 (41%) had some evidence of residual SP conduction. With median follow-up time of 1.9 [0.7-3.7] years, recurrence occurred in 14 patients (5%). Complete elimination of SP conduction (with and without isoproterenol) had a hazard ratio for recurrence of 1.26 (95% confidence interval [CI] 0.42-3.8; P = .68) on univariate analysis and 1.39 (95% CI 0.36-5.4; P = .63) on multivariate analysis (including demographics, ablation time, 8-mm cryocatheter, and baseline inducibility). CONCLUSION: The observed AVNRT recurrence rate after cryoablation was comparable to that of RFA. The presence of residual SP conduction was not associated with recurrence. This suggests that jump or single echo beat may be an acceptable endpoint in AVNRT cryoablation.

A low threshold for neonatal intervention yields a high rate of biventricular outcomes in pulmonary atresia with intact ventricular septum.

AIMS: Management strategies for pulmonary atresia with intact ventricular septum are variable and are based on right ventricular morphology and associated abnormalities. Catheter perforation of the pulmonary valve provides an alternative strategy to surgery in the neonatal period. We sought to assess the long-term outcome in terms of survival, re-intervention, and functional ventricular outcome in the setting of a 26-year single-centre experience of low threshold inclusion criteria for percutaneous valvotomy. METHODS AND RESULTS: Retrospective analysis of patients diagnosed with pulmonary atresia with intact ventricular septum from 1990 to 2016 at a tertiary referral centre, was performed. Of 71 patients, 48 were brought to the catheterisation laboratory for intervention. Catheter valvotomy was successful in 45 patients (94%). Twenty-three patients (51%) also underwent ductus arteriosus stenting. The length of intensive care and hospital stay was significantly shorter, and early re-interventions were significantly reduced in the catheterisation group. There were eight deaths (17%); all within 35 days of the procedure. Of the survivors, only one has required a Fontan circulation. Twenty-eight patients (74%) have undergone biventricular repair and nine patients (24%) have one-and-a-half ventricle circulation. Following successful valvotomy, 80% of patients required further catheter-based or surgical interventions. CONCLUSIONS: A low threshold for initial interventional management yielded a high rate of successful biventricular circulations. Although mortality was low in patients who survived the peri-procedural period, the rate of re-intervention remained high in all groups.

Pectoral nerve blocks decrease postoperative pain and opioid use after pacemaker or implantable cardioverter-defibrillator placement in children.

BACKGROUND: Pectoral nerve blocks (PECs) can reduce intraprocedural anesthetic requirements and postoperative pain. Little is known about the utility of PECs in reducing pain and narcotic use after pacemaker (PM) or implantable cardioverter-defibrillator (ICD) placement in children. OBJECTIVE: The purpose of this study was to determine whether PECs can decrease postoperative pain and opioid use after PM or ICD placement in children. METHODS: A single-center retrospective review of pediatric patients undergoing transvenous PM or ICD placement between 2015 and 2020 was performed. Patients with recent cardiothoracic surgery or neurologic/developmental deficits were excluded. Demographics, procedural variables, postoperative pain, and postoperative opioid usage were compared between patients who had undergone PECs and those who had undergone conventional local anesthetic (Control). RESULTS: A total of 74 patients underwent PM or ICD placement; 20 patients (27%) underwent PECs. There were no differences between PECs and Control with regard to age, weight, gender, type of device placed, presence of congenital heart disease, type of anesthesia, procedural time, or complication rates. Patients who underwent PECs had lower pain scores at 1, 2, 6, 18, and 24 hours compared to Control. PECs patients had a lower mean cumulative pain score [PECs 1.5 (95% confidence interval [CI] 0.8-2.2) vs Control 3.1 (95% CI 2.7-3.5); P <.001] and lower total opioid use [PECs 6.0 morphine milligram equivalent (MME)/m2 (95% CI 3.4-8.6) vs Control 15.0 MME/m2 (95% CI 11.8-18.2); P = .001] over the 24 hours postimplant. CONCLUSION: PECs reduce postoperative pain scores and lower total opioid usage after ICD or PM placement. PECs should be considered at the time of transvenous device placement in children.

Evaluation of a real-time magnetic resonance imaging-guided electrophysiology system for structural and electrophysiological ventricular tachycardia substrate assessment.

AIMS: Potential advantages of real-time magnetic resonance imaging (MRI)-guided electrophysiology (MR-EP) include contemporaneous three-dimensional substrate assessment at the time of intervention, improved procedural guidance, and ablation lesion assessment. We evaluated a novel real-time MR-EP system to perform endocardial voltage mapping and assessment of delayed conduction in a porcine ischaemia-reperfusion model. METHODS AND RESULTS: Sites of low voltage and slow conduction identified using the system were registered and compared to regions of late gadolinium enhancement (LGE) on MRI. The Sorensen-Dice similarity coefficient (DSC) between LGE scar maps and voltage maps was computed on a nodal basis. A total of 445 electrograms were recorded in sinus rhythm (range: 30-186) using the MR-EP system including 138 electrograms from LGE regions. Pacing captured at 103 sites; 47 (45.6%) sites had a stimulus-to-QRS (S-QRS) delay of ≥40 ms. Using conventional (0.5-1.5 mV) bipolar voltage thresholds, the sensitivity and specificity of voltage mapping using the MR-EP system to identify MR-derived LGE was 57% and 96%, respectively. Voltage mapping had a better predictive ability in detecting LGE compared to S-QRS measurements using this system (area under curve: 0.907 vs. 0.840). Using an electrical threshold of 1.5 mV to define abnormal myocardium, the total DSC, scar DSC, and normal myocardium DSC between voltage maps and LGE scar maps was 79.0 ± 6.0%, 35.0 ± 10.1%, and 90.4 ± 8.6%, respectively. CONCLUSION: Low-voltage zones and regions of delayed conduction determined using a real-time MR-EP system are moderately associated with LGE areas identified on MRI.

Real-time MRI guidance of cardiac interventions.

Cardiac magnetic resonance imaging (MRI) is appealing to guide complex cardiac procedures because it is ionizing radiation-free and offers flexible soft-tissue contrast. Interventional cardiac MR promises to improve existing procedures and enable new ones for complex arrhythmias, as well as congenital and structural heart disease. Guiding invasive procedures demands faster image acquisition, reconstruction and analysis, as well as intuitive intraprocedural display of imaging data. Standard cardiac MR techniques such as 3D anatomical imaging, cardiac function and flow, parameter mapping, and late-gadolinium enhancement can be used to gather valuable clinical data at various procedural stages. Rapid intraprocedural image analysis can extract and highlight critical information about interventional targets and outcomes. In some cases, real-time interactive imaging is used to provide a continuous stream of images displayed to interventionalists for dynamic device navigation. Alternatively, devices are navigated relative to a roadmap of major cardiac structures generated through fast segmentation and registration. Interventional devices can be visualized and tracked throughout a procedure with specialized imaging methods. In a clinical setting, advanced imaging must be integrated with other clinical tools and patient data. In order to perform these complex procedures, interventional cardiac MR relies on customized equipment, such as interactive imaging environments, in-room image display, audio communication, hemodynamic monitoring and recording systems, and electroanatomical mapping and ablation systems. Operating in this sophisticated environment requires coordination and planning. This review provides an overview of the imaging technology used in MRI-guided cardiac interventions. Specifically, this review outlines clinical targets, standard image acquisition and analysis tools, and the integration of these tools into clinical workflow. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2017;46:935-950.

Development, Preclinical Validation, and Clinical Translation of a Cardiac Magnetic Resonance - Electrophysiology System With Active Catheter Tracking for Ablation of Cardiac Arrhythmia.

OBJECTIVES: This study sought to develop an actively tracked cardiac magnetic resonance-guided electrophysiology (CMR-EP) system and perform first-in-human clinical ablation procedures. BACKGROUND: CMR-EP offers high-resolution anatomy, arrhythmia substrate, and ablation lesion visualization in the absence of ionizing radiation. Implementation of active tracking, where catheter position is continuously transmitted in a manner analogous to electroanatomic mapping (EAM), is crucial for CMR-EP to take the step from theoretical technology to practical clinical tool. METHODS: The setup integrated a clinical 1.5-T scanner, an EP recording and ablation system, and a real-time image guidance platform with components undergoing ex vivo validation. The full system was assessed using a preclinical study (5 pigs), including mapping and ablation with histological validation. For the clinical study, 10 human subjects with typical atrial flutter (age 62 ± 15 years) underwent MR-guided cavotricuspid isthmus (CTI) ablation. RESULTS: The components of the CMR-EP system were safe (magnetically induced torque, radiofrequency heating) and effective in the CMR environment (location precision). Targeted radiofrequency ablation was performed in all animals and 9 (90%) humans. Seven patients had CTI ablation completed using CMR guidance alone; 2 patients required completion under fluoroscopy, with 2 late flutter recurrences. Acute and chronic CMR imaging demonstrated efficacious lesion formation, verified with histology in animals. Anatomic shape of the CTI was an independent predictor of procedural success. CONCLUSIONS: CMR-EP using active catheter tracking is safe and feasible. The CMR-EP setup provides an effective workflow and has the potential to change the way in which ablation procedures may be performed.

Highlights of the 6th World Congress in Paediatric Cardiology and Cardiac Surgery.

The 6th World Congress in Paediatric Cardiology and Cardiac Surgery took place in Cape Town, South Africa, in February 2013. The congress is the largest meeting in the field of congenital and paediatric heart disease and attracts a global audience of specialists with the aim of sharing the latest multidisciplinary developments in research and clinical practice. The congress was commended as a huge success and this article aims to give a general flavor of the diverse meeting through detailing a few specific highlights from the various tracks.