Congenital and childhood atrioventricular blocks: pathophysiology and contemporary management.

UNLABELLED: Atrioventricular block is classified as congenital if diagnosed in utero, at birth, or within the first month of life. The pathophysiological process is believed to be due to immune-mediated injury of the conduction system, which occurs as a result of transplacental passage of maternal anti-SSA/Ro-SSB/La antibodies. Childhood atrioventricular block is therefore diagnosed between the first month and the 18th year of life. Genetic variants in multiple genes have been described to date in the pathogenesis of inherited progressive cardiac conduction disorders. Indications and techniques of cardiac pacing have also evolved to allow safe permanent cardiac pacing in almost all patients, including those with structural heart abnormalities. CONCLUSION: Early diagnosis and appropriate management are critical in many cases in order to prevent sudden death, and this review critically assesses our current understanding of the pathogenetic mechanisms, clinical course, and optimal management of congenital and childhood AV block. WHAT IS KNOWN: • Prevalence of congenital heart block of 1 per 15,000 to 20,000 live births. AV block is defined as congenital if diagnosed in utero, at birth, or within the first month of life, whereas childhood AV block is diagnosed between the first month and the 18th year of life. As a result of several different etiologies, congenital and childhood atrioventricular block may occur in an entirely structurally normal heart or in association with concomitant congenital heart disease. Cardiac pacing is indicated in symptomatic patients and has several prophylactic indications in asymptomatic patients to prevent sudden death. • Autoimmune, congenital AV block is associated with a high neonatal mortality rate and development of dilated cardiomyopathy in 5 to 30 % cases. What is New: • Several genes including SCN5A have been implicated in autosomal dominant forms of familial progressive cardiac conduction disorders. • Leadless pacemaker technology and gene therapy for biological pacing are promising research fields. In utero percutaneous pacing appears to be at high risk and needs further development before it can be adopted into routine clinical practice. Cardiac resynchronization therapy is of proven value in case of pacing-induced cardiomyopathy.

Spontaneous bacterial coronary sinus septic thrombophlebitis treated successfully medically.

A 38-year-old farmer was hospitalized for fever, chills, cough, and chest pain lasting for 7 days. Due to persistent symptoms, patient was referred to hospital. Blood cultures identified oxacillin-sensitive Staphylococcus aureus (OSSA). Transthoracic echocardiography (TTE) showed large pericardial effusion, a mobile heterogeneous mass originating from the coronary sinus ostium, no sign of valvular endocarditis. Pericardiocentesis was done carrying out purulent fluid, microbiological culture isolating an OSSA. Parenteral penicillin M was administered for 6 weeks. At the end of this antibiotherapy regimen, TTE showed no coronary sinus mass with complete vacuity of the coronary sinus vein and no pericardial effusion.

[Future of implantable electrical cardiac devices]. / L'avenir des dispositifs électriques implantables à visée cardiaque.

Major improvements in implantable electrical cardiac devices have been made during the last two decades, notably with the advent of automatic internal defibrillation (ICD) to prevent sudden arrhythmic death, and cardiac resynchronisation (CRT) to treat the discoordinated failing heart. They now constitute a major therapeutic option and may eventually supersede drug therapy. The coming era will be marked by a technological revolution, with improvements in treatment delivery, safety and efficacy, and an expansion of clinical indications. Leadless technologyfor cardiac pacemakers and defibrillators is already in the pipeline, endovascular leads currently being responsible for most long-term complications (lead failure, infection, vein thrombosis, etc.). Miniaturized pacemakers based on nanotechnology can now be totally implanted inside the right ventricle through the transvenous route, thus eliminating leads, pockets and scarring In the same way, totally subcutaneous ICD systems are now available, although they are currently only capable of delivering shocks, without pacing (including antitachycardia pacing). In CRT optimised delivery is important to improve clinical responses and to reduce the non-response rate (around 30 % with current technology). Endocardial left ventricular pacing could be a solution if it can be achieved at an acceptable risk. Multisite ventricular pacing is an alternative. Besides CRT neuromodulation, especially by vagal stimulation, is another important field of device researchfor heart failure. Preliminary clinical results are encouraging.

Parental electrocardiographic screening identifies a high degree of inheritance for congenital and childhood nonimmune isolated atrioventricular block.

BACKGROUND: The origin of congenital or childhood nonimmune isolated atrioventricular (AV) block remains unknown. We hypothesized that this conduction abnormality in the young may be a heritable disease. METHODS AND RESULTS: A multicenter retrospective study (13 French referral centers, from 1980-2009) included 141 children with AV block diagnosed in utero, at birth, or before 15 years of age without structural heart abnormalities and without maternal antibodies. Parents and matched control subjects were investigated for family history and for ECG screening. In parents, a family history of sudden death or progressive cardiac conduction defect was found in 1.4% and 11.1%, respectively. Screening ECGs from 130 parents (mean age 42.0 ± 6.8 years, 57 couples) were compared with those of 130 matched healthy control subjects. All parents were asymptomatic and in sinus rhythm, except for 1 with undetected complete AV block. Conduction abnormalities were more frequent in parents than in control subjects, found in 50.8% versus 4.6%, respectively (P<0.001). A long PR interval was found in 18.5% of the parents but never in control subjects (P<0.0001). Complete or incomplete right bundle-branch block was observed in 39.2% of the parents and 1.5% of the control subjects (P<0.0001). Complete or incomplete left bundle-branch block was found in 15.4% of the parents and 3.1% of the control subjects (P<0.0006). Estimated heritability for isolated conduction disturbances was 91% (95% confidence interval, 80%-100%). SCN5A mutation screening identified 2 mutations in 2 patients among 97 children. CONCLUSIONS: ECG screening in parents of children affected by idiopathic AV block revealed a high prevalence of conduction abnormalities. These results support the hypothesis of an inheritable trait in congenital and childhood nonimmune isolated AV block.

Characteristics and long-term outcome of non-immune isolated atrioventricular block diagnosed in utero or early childhood: a multicentre study.

AIMS: The natural history of congenital or childhood non-immune, isolated atrioventricular (AV) block is poorly defined. METHODS AND RESULTS: We retrospectively studied 141 children with isolated, non-immune AV block diagnosed in utero, or up to 15 years of age, at 13 French medical centres, between 1980 and 2009. Patients with structural heart disease or maternal antibodies were excluded. Atrioventricular block was asymptomatic in 119 (84.4%) and complete in 100 (70.9%) patients. There was progression to complete AV block in 29/41 (70.7%) patients with incomplete AV block over 2.8 ± 3.4 years (1-155 months), but all patients with incomplete AV block may not have been included in the study. Narrow QRS complex was present in 18 of 26 patients (69.2%) with congenital, and 106 of 115 (92.2%) with childhood AV block. Pacemakers were implanted in 112 children (79.4%), during the first year of life in 18 (16.1%) and before 10 years of age in 90 (80.4%). The mean interval between diagnosis of AV block and pacemaker implants was 2.6 ± 3.9 years (0-300 months). The pacing indication was prophylactic in 70 children (62.5%). During a mean follow-up of 11.6 ± 6.7 years (1-32 years), no patient died or developed dilated cardiomyopathy (DCM). The long-term follow-up was uncomplicated in 127 children (90.1%). CONCLUSION: In this large multicentre study, the long-term outcome of congenital or childhood non-immune, isolated AV block was favourable, regardless of the patient's age at the time of diagnosis. No patient died or developed DCM, and pacemaker-related complications were few.

Recurrences of Atrial Fibrillation Despite Durable Pulmonary Vein Isolation: The PARTY-PVI Study.

BACKGROUND: Recurrences of atrial fibrillation (AF) after pulmonary vein isolation (PVI) are mainly due to pulmonary vein reconnection. However, a growing number of patients have AF recurrences despite durable PVI. The optimal ablative strategy for these patients is unknown. We analyzed the impact of current ablation strategies in a large multicenter study. METHODS: Patients undergoing a redo ablation for AF and presenting durable PVI were included. The freedom from atrial arrhythmia after pulmonary vein-based, linear-based, electrogram-based, and trigger-based ablation strategies were compared. RESULTS: Between 2010 and 2020, 367 patients (67% men, 63±10 years, 44% paroxysmal) underwent a redo ablation for AF recurrences despite durable PVI at 39 centers. After durable PVI was confirmed, linear-based ablation was performed in 219 (60%) patients, electrogram-based ablation in 168 (45%) patients, trigger-based ablation in 101 (27%) patients, and pulmonary vein-based ablation in 56 (15%) patients. Seven patients (2%) did not undergo any additional ablation during the redo procedure. After 22±19 months of follow-up, 122 (33%) and 159 (43%) patients had a recurrence of atrial arrhythmia at 12 and 24 months, respectively. No significant difference in arrhythmia-free survival was observed between the different ablation strategies. Left atrial dilatation was the only independent factor associated with arrhythmia-free survival (HR, 1.59 [95% CI, 1.13-2.23]; P=0.006). CONCLUSIONS: In patients with recurrent AF despite durable PVI, no ablation strategy used alone or in combination during the redo procedure appears to be superior in improving arrhythmia-free survival. Left atrial size is a significant predictor of ablation outcome in this population.

Hypocalcaemia-induced transient dilated cardiomyopathy in elderly: a case report.

Hypocalcaemia is a rare cause of reversible heart failure. We reported a 76-year-old woman who had a severe systolic heart failure. She had severe hypocalcaemia due to hypoparathyroidism after thyroidectomy. Echocardiography showed a dilated left ventricle with a depressed left ventricular ejection fraction. Serum calcium level was low without other biological abnormalities. After calcium supplementation, heart failure improved rapidly. At 2 months, the calcium level was in a normal range and biventricular systolic and diastolic functions returned to normal.

Clinical predictors of challenging atrioventricular node ablation procedure for rate control in patients with atrial fibrillation.

INTRODUCTION: Atrioventricular node (AVN) ablation is usually a simple procedure but may sometimes be challenging. We aimed at identifying pre-procedural clinical predictors of challenging AVN ablation. METHODS: Patients referred for AVN ablation from 2009 to 2015 were retrospectively included. Baseline clinical data, procedural variables and outcomes of AVN ablation were collected. A "challenging procedure" was defined 1) total radiofrequency delivery to get persistent AVN block≥400s, 2) need for left-sided arterial approach or 3) failure to obtain AVN ablation. RESULTS: 200 patients were included (71±10years). A total of 37 (18.5%) patients had "challenging" procedures (including 9 failures, 4.5%), while 163 (81.5%) had "non-challenging" ablations. In multivariable analysis, male sex (Odds ratio (OR)=4.66, 95% confidence interval (CI): 1.74-12.46), body mass index (BMI, OR=1.08 per 1kg/m2, 95%CI 1.01-1.16), operator experience (OR=0.40, 95%CI 0.17-0.94), and moderate-to-severe tricuspid regurgitation (TR, OR=3.65, 95%CI 1.63-8.15) were significant predictors of "challenging" ablations. The proportion as a function of number of predictors was analyzed (from 0 to 4, including male sex, operator inexperience, a BMI>23.5kg/m2 and moderate-to-severe TR). There was a gradual increase in the risk of "challenging" procedure with the number of predictors by patient (No predictor: 0%; 1 predictor: 6.3%; 2 predictors: 16.5%; 3 predictors: 32.5%; 4 predictors: 77.8%). CONCLUSIONS: Operator experience, male sex, higher BMI and the degree of TR were independent predictors of "challenging" AVN ablation procedure. The risk increases with the number of predictors by patient.

Localization of gaps during redo ablations of paroxysmal atrial fibrillation: Preferential patterns depending on the choice of cryoballoon ablation or radiofrequency ablation for the initial procedure.

BACKGROUND: Pulmonary vein (PV) isolation, using cryoballoon or radiofrequency ablation, is the cornerstone therapy for symptomatic paroxysmal atrial fibrillation (AF) refractory to antiarrhythmic drugs. One-third of the patients have recurrences, mainly due to PV reconnections. AIMS: To describe the different locations of reconnection sites in patients who had previously undergone radiofrequency or cryoballoon ablation, and to compare the characteristics of the redo procedures in both instances. METHODS: Demographic data and characteristics of the initial ablation (cryoballoon or radiofrequency) were collected. Number and localization of reconduction gaps, and redo characteristics were reviewed. RESULTS: Seventy-four patients scheduled for a redo ablation of paroxysmal AF were included; 38 had been treated by radiofrequency ablation and 36 by cryoballoon ablation during the first procedure. For the initial ablation, procedural and fluoroscopy times were significantly shorter for cryoballoon ablation (147.8±52.6min vs. 226.6±64.3min [P<0.001] and 37.0±17.7min vs. 50.8±22.7min [P=0.005], respectively). Overall, an identical number of gaps was found during redo procedures of cryoballoon and radiofrequency ablations. However, a significantly higher number of gaps were located in the right superior PV for patients first ablated with radiofrequency (0.9±1.0 vs. 0.5±0.9; P=0.009). Gap localization displayed different patterns. Although not significant, redo procedures of cryoballoon ablation were slightly shorter and needed shorter durations of radiofrequency to achieve PV isolation. CONCLUSIONS: During redo procedures, gap localization pattern is different for patients first ablated with cryoballoon or radiofrequency ablation, and right superior PV reconnections occur more frequently after radiofrequency ablation. Redo ablation of a previous cryoballoon ablation appears to be easier.

Electrocardiographic correlates of mechanical dyssynchrony in recipients of cardiac resynchronization therapy devices.

BACKGROUND: The relationship between electrical and mechanical indices of cardiac dyssynchronization in systolic heart failure (HF) remains poorly understood. OBJECTIVES: We examined retrospectively this relationship by using the daily practice tools in cardiology in recipients of cardiac resynchronization therapy (CRT) systems. METHODS: We studied 119 consecutive patients in sinus rhythm and QRS ≥ 120 ms (mean: 160 ± 17 ms) undergoing CRT device implantation. P wave duration, PR, ePR (end of P wave to QRS onset), QT, RR-QT, JT and QRS axis and morphology were putative predictors of atrioventricular (diastolic filling time [DFT]/RR), interventricular mechanical dyssynchrony (IVMD) and left intraventricular mechanical dyssynchrony (left ventricular pre-ejection interval [PEI] and other measures) assessed by transthoracic echocardiography (TTE). Correlations between TTE and electrocardiographic measurements were examined by linear regression. RESULTS: Statistically significant but relatively weak correlations were found between heart rate (r=-0.5), JT (r=0.3), QT (r=0.3), RR-QT intervals (r=0.5) and DFT/RR, though not with PR and QRS intervals. Weak correlations were found between: (a) QRS (r=0.3) and QT interval (r=0.3) and (b) IVMD > 40 ms; and between (a) ePR (r=-0.2), QRS (r=0.4), QT interval (r=0.3) and (b) LVPEI, though not with other indices of intraventricular dyssynchrony. CONCLUSIONS: The correlations between electrical and the evaluated mechanical indices of cardiac dyssynchrony were generally weak in heart failure candidates for CRT. These data may help to explain the discordance between electrocardiographic and echocardiographic criteria of ventricular dyssynchrony in predicting the effect of CRT.

Left atrial function, a new predictor of response to cardiac resynchronization therapy?

BACKGROUND: Cardiac resynchronization therapy (CRT) improves left ventricular (LV) function and induces LV remodeling, and it is an established therapy for advanced heart failure with prolonged QRS duration. One third of patients will not benefit from this invasive therapy. OBJECTIVE: The purpose of this study was to evaluate whether left atrial (LA) strain imaging (ε) parameters could help in predicting the response in terms of LV reverse remodeling after CRT. METHODS: A total of 79 patients who underwent CRT were evaluated with echography before implantation. LA function and LV function were assessed with M-mode, 2-dimensional echocardiography, Doppler, tissue Doppler velocity, and ε. LV reverse remodeling was defined as a >15% reduction in LV end-systolic volume. RESULTS: At 6 months, 54 patients (68%) were responders to CRT. In multivariable logistic regression, LA systolic peak of strain rate (SRA) (odds ratio [OR} 10.5, 95% confidence interval [CI] 1.76-62.1, P = .01), left bundle branch block (OR 6.8, 95% CI 1.06-43.9, P = .04), ischemic cardiomyopathy (OR 3.93, 95% CI 1.07-14.4, P = .04), and LV preejection index (OR 1.03, 95% CI 1.01-1.05, P = .01) were associated with CRT response. With an SRA cutoff of -0.75%, the negative predictive value for predicting CRT response was 0.62. CONCLUSION: This study demonstrated the possible relevance of assessing LA function before CRT. SRA appeared to be a good predictor of CRT response. Integrating this LA function analysis into the multivariable assessment of patient candidates for CRT should be considered.

Pacemaker replacement in nonagenarians: Procedural safety and long-term follow-up.

BACKGROUND: The rate of pacemaker implantation is rising. Given that the life expectancy of the population is projected to increase, a large number of elderly patients are likely to be implanted in the future. As pacemaker batteries can last for 8-10years, an increasing number of pacemaker recipients will require replacement of their devices when they become nonagenarians. AIMS: To analyse the short- and long-term outcomes after device replacement in nonagenarians. METHODS: Patients aged≥90years referred to a tertiary centre for pacemaker replacement from January 2004 to July 2014 were included retrospectively. Clinical follow-up data were obtained from clinical visits or telephone interviews with patients or their families. The primary clinical endpoint was total mortality. Secondary endpoints included early and delayed procedure-related complications and predictive risk factors for total mortality. RESULTS: Sixty-two patients were included (mean age 93.3±2.9years at time of pacemaker replacement). Mean procedure duration was 35.7±17.2minutes. Mean hospital stay was 2.2±1.1days. One patient died from a perioperative complication. Thirty-seven patients (59.7%) died during a median follow-up of 22.1months (interquartile range, 11.8-39.8months). Survival rates were 84.2% (95% confidence interval [CI] 71.8-91.5%) at 1year, 66.9% (95% CI 51.8-78.2%) at 2years and 22.7% (95% CI 10.6-37.7%) at 5years. Atrial fibrillation (hazard ratio 2.47, 95% CI 1.1-5.6) and non-physiological pacing (i.e. VVI pacing in patients in sinus rhythm) (hazard ratio 2.20, 95% CI 1.0-4.9) were predictors of mortality. CONCLUSIONS: Pacemaker replacement in nonagenarians is a safe and straightforward procedure. These data suggest that procedures can be performed securely in this old and frail population, with patients living for a median of 30months afterwards.

Safety and efficacy of a second-generation cryoballoon in the ablation of paroxysmal atrial fibrillation.

BACKGROUND: Compared with the first-generation Arctic Front cryoballoon (ARC-CB), the new Arctic Front Advance cryoballoon (ARC-Adv-CB) increases the efficient CB-tissue contact surface during freezing, which may increase the incidence of phrenic nerve (PN) palsy (PNP). OBJECTIVE: To evaluate the safety and efficacy of paroxysmal atrial fibrillation (AF) ablation with the ARC-Adv-CB as well as the merits of a predictor of PNP. METHODS: AF ablation was performed by using a "single 28-mm big CB" approach. The rate of pulmonary vein (PV) isolation with a first cryoapplication was measured. The distance between the CB and a PN pacing catheter in the superior vena cava was measured to predict PNP during freezing. RESULTS: In 147 patients, PV were isolated with a single cryoapplication in 205 (81.3%) of 252 PV treated with the ARC-CB and in 280 (90.3%) of 310 PV treated with the ARC-Adv-CB (P = .003). The mean time to PV isolation was 52 ± 34 seconds and 40 ± 25 seconds (P < .001) and the temperature at the time of isolation was -36.1 ± 10.3°C and -32.3 ± 10.2°C (P = .001) in the ARC-CB and ARC-Adv-CB groups, respectively. Mean procedure and fluoroscopy durations were significantly shorter in the ARC-Adv-CB group. Transient PNP was observed in 7(10.6%) and 20(24.4%) of the patients treated with the ARC-CB and ARC-Adv-CB, respectively (P = .048). The distance between the lateral edge of the CB and a vertical line through the tip of the pacing catheter accurately predicted PNP (P < .001). CONCLUSIONS: The 28-mm ARC-Adv-CB enabled more efficient ablation of paroxysmal AF and shorter procedures than did the ARC-CB. This higher performance was associated with a higher incidence of PNP, which was predicted by the distance between the CB and the PN.