An unmet need: arrhythmia detection by implantable loop recorder in the systemic right ventricle.

AIMS: Patients with systemic right ventricles are at high risk of sudden cardiac death. Arrhythmia is a significant risk factor. Routine Holter monitoring is opportunistic with poor adherence. The aim of this study was to determine if continuous rhythm monitoring with an implantable loop recorder (ILR) could allow early detection of clinically important arrhythmias. METHODS AND RESULTS: Implantable loop recorder implantation was offered to patients with atrial switch repair for transposition of the great arteries. Recordings were made with symptoms or, automatically for pauses, significant bradycardia or tachycardia and reviewed by the multi-disciplinary team. Twenty-four out of 36 eligible patients underwent ILR implantation with no complication. Forty-two per cent had preserved ventricular function, 75% were NYHA functional class I, 88% had low sudden cardiac death risk, 33% had previous intra-atrial re-entrant tachycardia (IART), and none had known conduction disease. Eighteen out of 24 (75%) patients made 52 recordings (52% automated) over 39.5 months (1.6-72.5). Thirty-two out of 52 (62%) recordings in 15/24 (63%) of the cohort were clinically significant and included sinus node disease (two patients), atrioventricular block (two patients), IART (seven patients), and IART with sinus node disease or atrioventricular block (four patients). Implantable loop recorder recordings prompted medication change in 11 patients [beta-blockers (n = 9), anti-coagulation (n = 5), and stopping anti-coagulation (n = 1)] and device therapy recommendation in seven patients [five pacemakers (three: atrioventricular block) and two defibrillators]. Two patients declined intervention; one suffered an arrhythmic death. Intra-atrial re-entrant tachycardia and clinically relevant conduction disease were detected in patients irrespective of sudden cardiac death risk. CONCLUSION: Continuous monitoring with an ILR in patients with systemic right ventricle following atrial switch detects clinically relevant arrhythmias that impact decision-making. In this cohort, clinically relevant arrhythmias did not correlate with sudden cardiac death risk.

Ventricular assist devices in transposition and failing systemic right ventricle: role of tricuspid valve replacement.

OBJECTIVES: Ventricular assist device (VAD) for systemic right ventricular (RV) failure patients post-atrial switch, for transposition of the great arteries (TGA), and those with congenitally corrected TGA has proven useful to reduce transpulmonary gradient and bridge-to-transplantation. The purpose of this study is to describe our experience of VAD in systemic RV failure and our move towards concomitant tricuspid valve replacement (TVR). METHODS: This is a single-centre retrospective study of consecutive adult patients receiving HeartWare VAD for systemic RV failure between 2010 and 2019. From 2017, concomitant TVR was performed routinely. Demographic, clinical variables and echocardiographic and haemodynamic measurements pre- and post-VAD implantation were recorded. Complications on support, heart transplantation and survival rates were described. RESULTS: Eighteen patients underwent VAD implantation. Moderate or severe systemic tricuspid regurgitation was present in 83.3% of patients, and subpulmonic left ventricular impairment in 88.9%. One-year survival was 72.2%. VAD implantation was technically feasible and successful in all but one. Post-VAD, transpulmonary gradient fell from 16 (15-22) to 10 (7-13) mmHg (P = 0.01). Patients with TVR (n = 6) also demonstrated a reduction in mean pulmonary and wedge pressures. Furthermore, subpulmonic left ventricular end-diastolic dimension (44.3 vs 39.6 mm; P = 0.03) and function improved in this group. After 1 year of support, 72.2% of patients were suitable for transplantation. CONCLUSIONS: VAD is an effective strategy as bridge-to-candidacy and bridge-to-transplantation in patients with end-stage systemic RV failure. Concomitant TVR at the time of implant is associated with better early haemodynamic and echocardiographic results post-VAD.

Cardiac stereotactic ablative radiotherapy for control of refractory ventricular tachycardia: initial UK multicentre experience.

BACKGROUND: Options for patients with ventricular tachycardia (VT) refractory to antiarrhythmic drugs and/or catheter ablation remain limited. Stereotactic radiotherapy has been described as a novel treatment option. METHODS: Seven patients with recurrent refractory VT, deemed high risk for either first time or redo invasive catheter ablation, were treated across three UK centres with non-invasive cardiac stereotactic ablative radiotherapy (SABR). Prior catheter ablation data and non-invasive mapping were combined with cross-sectional imaging to generate radiotherapy plans with aim to deliver a single 25 Gy treatment. Shared planning and treatment guidelines and prospective peer review were used. RESULTS: Acute suppression of VT was seen in all seven patients. For five patients with at least 6 months follow-up, overall reduction in VT burden was 85%. No high-grade radiotherapy treatment-related side effects were documented. Three deaths (two early, one late) occurred due to heart failure. CONCLUSIONS: Cardiac SABR showed reasonable VT suppression in a high-risk population where conventional treatment had failed.

Outcomes From Pediatric Ablation: A Review of 20 Years of National Data.

OBJECTIVES: This study set out to examine outcomes from pediatric supraventricular tachycardia ablations over a 20-year period. This study sought to examine success rates and repeat ablations over time and to evaluate whether modalities such as 3-dimensional (3D) mapping, contact force, and cryotherapy have improved outcomes. BACKGROUND: Ablation of supraventricular tachycardia in pediatric patients is commonly performed in most congenital heart centers with excellent long-term results. METHODS: Data were retrieved from the NICOR (National Institute of Clinical Outcomes Research) database in the United Kingdom. Outcomes over time were evaluated, and procedure-related details were compared. RESULTS: There were 7,069 ablations performed from January 1, 1999, to December 31, 2018, at 10 centers. Overall, ablation success rates were 92% for accessory pathways, 97% for atrioventricular node re-entry tachycardia, and 89% for atrial tachycardia. There was an improvement in procedural success rates over time (p < 0.01). The use of 3D mapping did not alter success or need for repeat ablation but was associated with a higher proportion of lower fluoroscopy cases; 55% of 3D mapping cases used <5 min of fluoroscopy (p < 0.01). Patients needing a repeat ablation were 341 (12%) for accessory pathways, 128 (7%) for atrioventricular node re-entry tachycardia, and 35 (7%) for atrial tachycardia. Overall, the risk of complete heart block was low (n = 12, <0.01%). The use of cryotherapy was associated with an increased risk of needing a repeat ablation. CONCLUSIONS: Overall success rates from pediatric ablations are excellent and compare favorably to other registries. Introduction of newer technologies have likely made procedures safer and reduced radiation exposure, but they have not changed success rates or the need for a repeat procedure.

Ultra-High-Density Activation Mapping to Aid Isthmus Identification of Atrial Tachycardias in Congenital Heart Disease.

OBJECTIVES: A new electroanatomic mapping system (Rhythmia, Boston Scientific, Marlborough, Massachusetts) using a 64-electrode mapping basket is now available; we systematically assessed its use in complex congenital heart disease (CHD). BACKGROUND: The incidence of atrial arrhythmias post-surgery for CHD is high. Catheter ablation has emerged as an effective treatment, but is hampered by limitations in the mapping system's ability to accurately define the tachycardia circuit. METHODS: Mapping and ablation data of 61 patients with CHD (35 males, age 45 ± 14 years) from 8 tertiary centers were reviewed. RESULTS: Causes were as follows: Transposition of Great Arteries (atrial switch) (n = 7); univentricular physiology (Fontans) (n = 8); Tetralogy of Fallot (n = 10); atrial septal defect (ASD) repair (n = 15); tricuspid valve (TV) anomalies (n = 10); and other (n = 11). The total number of atrial arrhythmias was 86. Circuits were predominantly around the tricuspid valve (n = 37), atriotomy scar (n = 10), or ASD patch (n = 4). Although the majority of peri-tricuspid circuits were cavo-tricuspid-isthmus dependent (n = 30), they could follow a complex route between the annulus and septal resection, ASD patch, coronary sinus, or atriotomy. Immediate ablation success was achieved in all but 2 cases; with follow-up of 12 ± 8 months, 7 patients had recurrence. CONCLUSIONS: We demonstrate the feasibility of the basket catheter for mapping complex CHD arrhythmias, including with transbaffle and transhepatic access. Although the circuits often involve predictable anatomic landmarks, the precise critical isthmus is often difficult to predict empirically. Ultra-high-density mapping enables elucidation of circuits in this complex anatomy and allows successful treatment at the isthmus with a minimal lesion set.

Outcome for children following admission to hospital with a first episode of heart failure, due to heart muscle disease, in the ventricular assist device (VAD) era.

AIMS: Most reports on the outcome of children who present with heart failure, due to heart muscle disease, are from an era when ventricular assist devices were not available. This study provides outcome data for the current era where prolonged circulatory support can be considered for most children. METHODS & RESULTS: Data was retrieved on 100 consecutive children, who presented between 2010 - 2016, with a first diagnosis of unexplained heart failure. Hospital outcome was classified as either death, transplantation, recovery of function or persistent heart failure. Median age at presentation was 24 months and 58% were < 5 years old. Hospital mortality was 12% and 59% received a heart transplant. Most, 79%, of the transplants were carried out on patients with a device. Recovery of function was observed in 18% and 10% stabilised on oral therapy. Eighty-four percent of the deaths occurred in the <5 year old group. Shorter duration of support was associated with survival (34 days in survivors versus 106 in non-survivors, p = 0.01) and 72% were on an assist device at time of death. CONCLUSION: Heart failure in children who require referral to a transplant unit is a serious illness with a high chance of either transplantation or death. Modifications in assist devices will be required to improve safety, especially for children < 5 years old where the donor wait may be prolonged. The identification of children who may recover function requires further study.

Outcome following heart transplant assessment in adults with congenital heart disease.

OBJECTIVES: Adults with congenital heart disease (ACHD) are a growing group with end-stage heart failure. We aim to describe the outcomes of ACHD patients undergoing assessment for orthotopic heart transplant (OHT). METHODS: Case notes of consecutive ACHD patients (>16 years) assessed for OHT between 2000 and 2016 at our centre were reviewed. Decision and outcome were reported as of 2017. Data were analysed in three groups: systemic left ventricle (LV), systemic right ventricle (RV) and single ventricle (SV). RESULTS: 196 patients were assessed (31.8 years, 27% LV, 29% RV, 44% SV). 89 (45%) patients were listed for OHT and 67 (34%) were transplanted. 41 (21%) were unsuitable or too high risk and 36 (18%) were too well for listing. Conventional surgery was undertaken in 13 (7%) and ventricular assist device in 17 (9%) with 7 (4%) bridged to candidacy. Survival from assessment was 84.2% at 1 year and 69.7% at 5 years, with no difference between groups. Patients who were considered unsuitable for OHT (HR 11.199, p<0.001) and listed (HR 3.792, p=0.030) were more likely to die than those who were considered too well. Assessments increased over the study period. CONCLUSIONS: The number of ACHD patients assessed for OHT is increasing. A third are transplanted with a small number receiving conventional surgery. Those who are unsuitable have a poor prognosis.

How many versus how much: comprehensive haemodynamic evaluation of partial anomalous pulmonary venous connection by cardiac MRI.

OBJECTIVES: The objective of this study was to investigate the effect of location and number of anomalously connected pulmonary veins and any associated atrial septal defect (ASD) on the magnitude of left-to-right shunting in patients with partial anomalous pulmonary venous connection (PAPVC), and how that influences right ventricular volume loading. METHODS AND RESULTS: The cardiac magnetic resonance (CMR) and echocardiography examinations of 26 paediatric patients (mean age, 11.2 ± 5.1 years) with unrepaired PAPVC were analysed. Fourteen patients had right-sided, 11 left-sided and 1 patient bilateral PAPVC. An ASD was present in 11 patients, of which none had a Qp/Qs < 1.5 and 8 had a Qp/Qs≥ 2.0. No patient with isolated left upper PAPVC experienced a Qp/Qs ≥ 2.0 compared to 9/12 patients with right upper PAPVC. Qp/Qs correlated with indexed right ventricle (RV) end-diastolic volume (RVEDVi, r = 0.59, p = 0.002) by CMR and with echocardiographic right ventricular end-diastolic dimension (RVED) z-score (r = 0.68, p = 0.003). A RVEDVi >124 ml/m2 by CMR and a RVED z-score >2.2 by echocardiography identified patients with a Qp/Qs ≥1.5 with good sensitivity and specificity. CONCLUSIONS: An asymptomatic patient with a single anomalously connected left upper pulmonary vein and without an ASD is unlikely to have a significant left-to-right shunt. On the other hand, right-sided PAPVC is frequently associated with a significant left-to-right shunt, especially when an ASD is present. KEY POINTS: • Patients with PAPVC and ASD routinely have a significant left-to-right shunt. • Patients with right PAPVC are likely to have a significant left-to-right shunt. • Patients with left PAPVC are unlikely to have a significant left-to-right shunt. • CMR is helpful in decision-making for patients with PAPVC.

A multicentre study of patients with Timothy syndrome.

Aims: Timothy syndrome (TS) is an extremely rare multisystem disorder characterized by marked QT prolongation, syndactyly, seizures, behavioural abnormalities, immunodeficiency, and hypoglycaemia. The aim of this study was to categorize the phenotypes and examine the outcomes of patients with TS. Methods and results: All patients diagnosed with TS in the United Kingdom over a 24-year period were reviewed. Fifteen centres in the British Congenital Arrhythmia Group network were contacted to partake in the study. Six patients with TS were identified over a 24-year period (4 boys and 2 girls). Five out of the six patients were confirmed to have a CACNA1C mutation (p.Gly406Arg) and the other patient was diagnosed clinically. Early presentation with heart block, due to QT prolongation was frequently seen. Four are still alive, two of these have a pacemaker and two have undergone defibrillator implantation. Five out of six patients have had a documented cardiac arrest with three occurring under general anaesthesia. Two patients suffered a cardiac arrest while in hospital and resuscitation was unsuccessful, despite immediate access to a defibrillator. Surviving patients seem to have mild developmental delay and learning difficulties. Conclusion: Timothy syndrome is a rare disorder with a high attrition rate if undiagnosed. Perioperative cardiac arrests are common and not always amenable to resuscitation. Longer-term survival is possible, however, patients invariably require pacemaker or defibrillator implantation.

Mechanisms of tricuspid valve regurgitation in hypoplastic left heart syndrome: a case-matched echocardiographic-surgical comparison study.

AIMS: The multifactorial mechanisms of tricuspid valve (TV) insufficiency in patients with hypoplastic left heart syndrome (HLHS) include structural anomalies of TV leaflets and ventricular dilatation. We hypothesized that 2-D echocardiography underestimates the importance of TV structural abnormalities, whereas surgical assessment underestimates the importance of motion abnormalities, and compared echocardiographic assessment with surgical description. METHODS AND RESULTS: Two independent experts retrospectively reviewed echocardiograms of all patients who had staged single-ventricular palliation and TV repair during January 1998-December 2008, and compared with case-matched controls who did not require TV repair. Primary and secondary mechanisms of TV insufficiency were categorized, and surgical findings ascertained from operation records. There were 32 patients with a median age of 5.9 months (0.3-140) and 32 matched controls. On echocardiographic review, an abnormality of at least one leaflet was noted in every patient (100%) vs. in only 14 controls 14 (44%) (P < 0.001). Leaflet prolapse was described in 22 (69%), and the restriction of a leaflet in 20 (69%). Agreement between the experts was excellent (κ = 0.64-0.88). On surgical inspection, annular dilatation was found in 17 (53%), and leaflet dysplasia in 14 (44%). Agreement between echocardiographic and surgical assessment was poor (κ < 0.6). CONCLUSION: Important structural abnormalities are common in patients with HLHS and TV insufficiency, some readily identified by 2-D echocardiography. However, there are significant discrepancies between echocardiographic and surgical findings. Echocardiographic assessment is sensitive to detect leaflet motion abnormalities, but not leaflet structural abnormalities. Both echocardiographers and surgeons should be aware of these limitations when planning surgical interventions.

Arrhythmia associated with tetracaine in an extremely low birth weight premature infant.

Infants in NICUs undergo a variety of painful procedures. The management of pain has become an integral part of newborn infant care with the use of both systemic and topical agents to provide analgesia and anesthesia for procedural pain. Tetracaine and prilocaine-lidocaine are the 2 topical anesthetics most frequently used. Tetracaine belongs to an ester group of local anesthetics available as a topical 4% gel (Ametop, Smith and Nephew, Canada). The major side effects reported when using topical anesthetics are cutaneous reactions. There are no definite reports of systemic toxicity in the published literature. We present a recent case of an extremely low birth weight premature infant who developed a clinically significant arrhythmia after topical tetracaine was applied before the insertion of a peripherally inserted central catheter. The infant had no other identifiable cause for the resulting bradycardia that occurred only after Ametop was applied. The cardiac symptoms resolved with treatment. This case highlights a significant potential adverse event when using topical tetracaine.

Influence of RV restrictive physiology on LV diastolic function in children after tetralogy of Fallot repair.

BACKGROUND: Restrictive right ventricular (RV) physiology is a common finding after tetralogy of Fallot repair. Via diastolic ventricular interaction, RV filling characteristics may influence left ventricular (LV) filling. The aim of this study was to analyze the effect of RV diastolic physiology on LV diastolic properties. METHODS: This was a retrospective study including 112 pediatric patients after tetralogy of Fallot repair who underwent full echocardiographic evaluations. Restrictive RV physiology was defined as the presence of end-diastolic forward flow in the main pulmonary artery as detected in at least three consecutive cardiac cycles. RV and LV diastolic function was assessed by analyzing mitral or tricuspid inflow patterns, pulmonary venous flow traces, and pulsed tissue Doppler velocities at the tricuspid and mitral annuli. RESULTS: The mean age at the time of study was 12.9 ± 3.2 years. Restrictive RV physiology was identified in 58 of 112 patients (52%). Patients with RV restriction had larger right atrial and RV dimensions, as well as increased left atrial length and left atrial indexed volume compared with nonrestrictive patients. No differences were found in LV dimensions. Although parameters reflecting early LV diastolic filling (mitral E velocity, lateral annular E' velocity, isovolumetric relaxation time, and E/E' ratio) were not different between the restrictive and nonrestrictive patients, those reflecting late filling were different, with a significantly higher pulmonary venous A-wave reversal velocity and duration in the restrictive group (P < .001). Also, the difference between pulmonary venous A-wave reversal and mitral valve A-wave duration was higher in the restrictive group (P = .0007). CONCLUSIONS: End-diastolic forward flow in the main pulmonary artery is associated with larger RV dimensions in pediatric patients with postoperative tetralogy of Fallot. The presence of end-diastolic forward flow was not associated with other differences in RV diastolic parameters but with more pronounced pulmonary venous reversals and larger left atrial size. This indicates that ventricular diastolic interaction affects LV filling pressures.

Intractable intracranial tuberculous infection responsive to thalidomide: report of four cases.

Paradoxical enlargement and development of new intracranial tuberculomas and tuberculous brain abscesses on adequate antituberculosis treatment are well recognized and supposedly cytokine mediated. These lesions are often unresponsive to conventional antituberculosis treatment, corticosteroids, and surgery. We therefore assessed the effect of adjunctive thalidomide, a tumor necrosis factor alpha-modulating drug, in intractable intracranial tuberculosis that did not respond to standard medical and surgical therapy. Four consecutive children (three children with bacteriologic proof and one child with clinical evidence of intracranial tuberculosis) were studied. Three patients each had a giant tuberculous abscess, and the fourth had chronic basal arachnoiditis with progressive loss of vision. Three of the four patients had relentless neurologic deterioration, and all showed disease progression on neuroimaging despite full medical and appropriate surgical treatment. Marked clinical and neuroradiologic improvement occurred after thalidomide was added to the antituberculosis treatment regimen of these four patients. Adjunctive thalidomide might have a role in the management of intractable intracranial tuberculosis and needs further investigation in this regard.