Atrial Arrhythmias and AV Block in Congenital Heart Disease

Posted on Apr 5, 2025 in Health and Nursing

Atrial Arrhythmias (Including AV Block) in Congenital Heart Disease

INTRODUCTION — One of the striking successes in caring for patients with congenital heart disease (CHD) over the last few decades is the improved longevity. Almost one million adults with CHD are now living in the United States [1-3]; up to half having undergone at least one open heart surgical procedure resulting in one or more residual atrial scars [4]. For the purposes of this topic, CHD does not include bicuspid valves.

As a consequence of both the added longevity and the atrial scarring from many of the surgical procedures, atrial arrhythmias are increasingly recognized in this group. They are a major cause of hospital admission and morbidity in patients with CHD [5-7]. These rhythm abnormalities, which are often benign in the general population, may be poorly tolerated and are associated with an almost 50 percent increase in mortality compared with those patients without atrial arrhythmias [7].

Although all forms of atrial bradycardia and tachycardia can adversely affect both children and adults with CHD, there are particular considerations in this group because of the anatomy and prior surgical repairs. Although some arrhythmias are intrinsic to the cardiac maldevelopment itself, most are secondary to surgical scars and chronic hemodynamic burden.

This review will focus on the management of these arrhythmias (table 1), which should involve a comprehensive multidisciplinary approach.

PREVALENCE AND INCIDENCE — Excluding bicuspid aortic valvulopathy, around 1 percent of live births have some element of congenital heart disease (CHD) (table 2). Minor racial differences in the incidence appear to be the case in the United States, and international variation is not known [8]. Of these, about 45 percent present with simpler forms of disease, such as atrial septal defects (ASD) and ventricular septal defects (VSD), somewhat less frequency of moderate forms of CHD such as tetralogy of Fallot, and the remainder have more complex CHD [9]. The epidemiology of CHD is discussed in detail elsewhere. (See “Identifying newborns with critical congenital heart disease”, section on ‘Epidemiology’.)

The abnormal hemodynamics associated with many cases of CHD (through atrial stretch and concomitant fibrosis) exaggerate an arrhythmogenic milieu and increase the likelihood of atrial arrhythmias over time. (See “Classification of atrial septal defects (ASDs), and clinical features and diagnosis of isolated ASDs in children” and “Management and outcome of isolated atrial septal defects in children” and “Management and outcome of tetralogy of Fallot” and “Pathophysiology, clinical features, and diagnosis of tetralogy of Fallot”.)

In addition to the tachyarrhythmias, symptomatic bradyarrhythmias can cause considerable morbidity in patients with CHD. Pacemaker implantation is required for bradyarrhythmias in up to 3 to 4 percent of patients after surgical ASD closure, and for patients with Ebstein’s anomaly [10]. Pacemaker placement is also indicated in about 7 percent of Fontan patients [11,12], and over 80 percent of patients who have undergone atrial switch procedures for d-transposition of the great arteries [13]. (See “Ebstein’s anomaly of the tricuspid valve”.)

Longitudinal studies suggest that as a whole, atrial tachyarrhythmias afflict at least 20 percent of individuals with CHD over their lifetime [7]. Approximately half of patients with ASD repair over age 25 years [14] and nearly one-third of patients with tetralogy of Fallot develop atrial tachyarrhythmias [15]. (See “Identification and assessment of atrial septal defects in adults” and “Clinical manifestations and diagnosis of atrial septal defects in adults” and “Atrial septal abnormalities (PFO, ASD, and ASA) and risk of cerebral emboli in adults” and “Treatment of atrial septal abnormalities (PFO, ASD, and ASA) for prevention of stroke in adults”.)

The atrial tachyarrhythmias are associated with a higher morbidity and mortality in patients with CHD, and a worse functional class. Single-ventricle, pulmonary hypertension and valvular heart disease are also all independently associated with a higher risk of death in the patients with atrial tachyarrhythmias [16].

These arrhythmias are seen in up to half of patients with the more complex repairs such as the classical Fontan operation [12,17], and in response to this, novel surgical approaches have lead to the development of extracardiac conduit bypasses to exclude the right atrium and the nidus for atrial arrhythmias [18,19].

The frequency of congenital heart disease as a cause of atrial arrhythmias in the fetal heart is discussed separately. (See “Overview of the general approach to diagnosis and treatment of fetal arrhythmias”.)

PATHOPHYSIOLOGY — Bradycardia can be inherent to the congenital anomaly, such as abnormalities of the sinus node or atrioventricular (AV) node in the heterotaxy (isomerism) syndromes, L-transposition of great arteries, or AV septal defects [20,21]. However, bradycardia is most commonly seen secondary to iatrogenic disruption of these structures and can occur in both the early postoperative period or many years after the operation, presumably driven by fibrosis [12,13,22-24] (table 1). (See “Bradycardia in children”.)

Tachycardias most commonly have a re-entrant mechanism and are facilitated by abnormal atrial substrate adjacent to valves, patches, or suture lines. In addition, cellular injury from longstanding hypoxia and atrial stretch conceivably also engenders inhomogeneity in myocardial refractoriness and hence adds to the arrhythmogenic milieu [25] (table 1). (See “Approach to the child with tachycardia”.)

Bradycardias

Congenital sinus node dysfunction — Sinus venosus atrial septal defects (ASD) (occurring in the septum between the superior vena cava and right-sided pulmonary veins) account for around 5 to 10 percent of all ASDs [26,27]. Due to the location of this defect, congenital sinus node dysfunction is commonly found [28]. This is also the case in the more rare CHD lesions that involve the heterotaxy syndromes or juxtaposed atrial appendages [29]. (See “Clinical manifestations and diagnosis of atrial septal defects in adults”, section on ‘Sinus venosus ASD’ and “Overview of the general approach to diagnosis and treatment of fetal arrhythmias”.)

Acquired sinus node dysfunction — Any procedure involving an atriotomy such as cannulation for cardiopulmonary bypass potentially risks injury to the sinus node by virtue of its location. More extensive congenital operations involving atrial repair pose substantial risk to the sinus node. These include the atrial switch (Mustard/Senning), Glenn, Fontan, and Ebstein’s repairs [12,13,22,30]. Patients may present with an overt loss of sinus rhythm or a poor chronotropic response to exercise [13,22]. (See “Pregnancy in women with congenital heart disease: Specific lesions”.)

Congenital AV block — The atrioventricular (AV) node is a right atrial structure, whereas the His bundle, the electrical continuation of the AV node, is a ventricular structure. Disorders of misalignment of these two contiguous chambers frequently result in interruption of AV conduction. These anomalies include congenitally corrected transposition of the great arteries (ccTGA, a.k.a. L-TGA), large primum ASDs, and large AV septal defects (AV canal defects) [21,31]. These malformations can result in either complete heart block or progressive AV conduction disease, which is seen in over 20 percent of unoperated ccTGA [32] and around 5 percent of unoperated primum ASDs [33]. (See “Pregnancy in women with congenital heart disease: Specific lesions”, section on ‘Congenitally corrected transposition of the great arteries’ and “Management and outcome of atrioventricular (AV) canal defects”, section on ‘Arrhythmias’ and “Clinical manifestations, pathophysiology, and diagnosis of atrioventricular (AV) canal defects”, section on ‘Electrocardiography’.)

Acquired AV node dysfunction — Surgical trauma in the region of the atrioventricular conduction axis occurs most commonly with operations that involve this region, such as ventricular septal defect repair, left ventricular outflow tract resection or atrioventricular valve replacement [23].

Tachycardias

Intraatrial reentrant tachycardia — Atrial scars in repaired CHD patients provide a fundamental element for the development of intraatrial reentrant tachycardia (IART), which is the most common atrial tachyarrhythmia [30] in this population. (See “Intraatrial reentrant tachycardia”.) Mechanistically, IART is similar to atrial flutter, with a macro-reentrant circuit requiring a zone of slow conduction that develops in diseased tissue and is bordered by scars/valve or vena cava.

Found primarily in patients where the atrial tissue is damaged through chronic stretch or operative scars, these circuits usually develop many years after the original intervention [34,35]. Classical intracardiac Fontan repairs, which utilize atrial tissue and the Mustard/Senning procedures, are most commonly associated with this arrhythmia. They can occur also with simple atriotomy scars (figure 1). Concomitant sinus node dysfunction and older age at first surgical repair also appear to increase the incidence [12]. The atrial rate may vary between 150 and 250 beats per minute, and in the presence of preserved AV nodal function, the ensuing ventricular response may be 1:1, with rapid clinical deterioration.

Atrial fibrillation — The pulmonary venous origins of paroxysmal atrial fibrillation in CHD do not appear to differ markedly from acquired heart disease. [36]. Left heart lesions with subsequent left atrial stretch and fibrosis are most commonly associated with this rhythm abnormality. Associated coronary disease or lesions involving the left ventricular outflow tract and/or mitral valve are the more commonly related lesions [37].

Ectopic/focal atrial tachycardia — The precise etiology and prevalence of this arrhythmia in CHD is less clear. (See “Focal atrial tachycardia”.) It is far less common than intraatrial reentrant tachycardia (IART), and appears to be more prevalent in children than in adults with CHD [38]. It may originate from atrial tissue within the Fontan circuit, from the atrial appendages, or adjacent to the pulmonary veins. On the surface electrocardiogram (ECG), this arrhythmia can be identified by the unusual p-wave axis and a progressive increase in the rate. Catheter ablation of the focus, however, is associated with much higher rates of success than IART, and provides an excellent chance of cure [39].

Evaluation

Cardiac referral and further evaluation — The management and treatment of patients with congenital heart disease (CHD) and atrial arrhythmias are often much more complex than more typical arrhythmia patients. As recommended in the 2008 American Heart Association/American College of Cardiology guidelines for the management of CHD, these patients should be referred to centers that routinely follow this population [40]. Importantly, atrial arrhythmias can be a harbinger of underlying hemodynamic deterioration and a comprehensive hemodynamic assessment is vital.

History — A thorough surgical history, including operative reports, is necessary. This information is critical not only in the diagnostic work-up of the atrial arrhythmia, but also in identifying whether venous access for catheters or permanent pacing is feasible. Similarly, during pacing or ablation procedures, inadvertent injury to the AV conduction system may occur. In these instances, it is critical to know whether a route to rapidly transvenously pace the ventricle is available.

Physical examination — The physical examination is important in order to identify evidence for concomitant hemodynamic compromise, which may be integral to the arrhythmia development. For example, the presence of peripheral edema, ascites, and an enlarged liver might identify Fontan failure, and revision of this conduit may prove to be the primary intervention for worsening atrial arrhythmias.

Electrocardiogram — The twelve-lead electrocardiogram (ECG) is instrumental in clarifying the underlying rhythm disturbance, yet can frequently be misleading in CHD patients [41]. Patients with intra-atrial re-entrant tachycardia (IART) often have slower atrial rates with discrete p-waves and an isoelectric interval (as opposed to typical saw-tooth cavo-tricuspid isthmus dependent flutter). This rhythm is occasionally mistaken for sinus tachycardia as the p-wave can be buried in the preceding QRS complex or in the setting of 1:1 conduction through a healthy atrioventricular (AV) node (waveform 1). Patients who have undergone modified Maze surgeries often have very little evidence of atrial activity on the ECG, making electrocardiographic diagnosis challenging [42]. (See “Surgical ablation to prevent recurrent atrial fibrillation” and “Surgical ablation to prevent recurrent atrial fibrillation”, section on ‘Maze procedure’.)

An underlying IART may be missed in this instance and running a longer rhythm strip can be helpful to identify grouped beating occurring in the context of variable AV block. The T wave should also be scrutinized for any sharp deflections not usually associated with repolarization, and hence indicative of atrial depolarization.

Echocardiogram — The transthoracic echocardiogram is invaluable in identifying structural and hemodynamic cardiac disorders that may have precipitated the rhythm disturbance. Conduit or valvular dysfunction may lead to secondary effects on the atrial muscle and thus a CHD specialist should interpret the echocardiograms in these patients. The echo examination may also provide the first clue to an atrial rhythm disturbance or demonstrate reduction in ventricular function from tachycardia. Advances in prenatal diagnosis have allowed preemptive identifications of cardiac anomalies, and this should be considered in fetuses at increased risk. (See “Fetal cardiac abnormalities: Screening, evaluation, and pregnancy management”.)

Ambulatory ECG/Holter monitoring — Twenty-four-hour Holter recordings are important tools to identify the underlying rhythm abnormality when the patient’s ECG is unrevealing and there is a history of presyncope, syncope, or palpitations [43]. In addition, this can also be a useful adjunctive investigation when chronotropic incompetence is suspected, due to underlying sinus, AV node or medication-related bradycardia. (See “Ambulatory ECG monitoring”.)

Event monitor — The event monitor is used to identify the etiology of short-lived symptoms that cannot be characterized by the ECG or Holter recordings. One- to three-month periods of transient cardiac event monitors or looping recorders are frequently employed diagnostically, and implantable loop recorders can be considered for patients with erratic symptoms. (See “Ambulatory ECG monitoring”.)

Exercise testing — Exertional symptoms can be evaluated with either treadmill or bicycle stress tests. Catecholaminergic surges that develop during maximal effort can precipitate arrhythmias by influencing conduction velocity and refractoriness. In addition, faster atrioventricular node function during exercise may allow 1:1 conduction in the context of a previously undiagnosed atrial tachycardia. (See “Exercise ECG testing: Performing the test and interpreting the ECG results”.)

Electrophysiology study — The electrophysiology study (EPS) is rarely used to evaluate atrial bradyarrhythmia. However, patients who have undergone extensive atrial surgery, such as right reduction atrioplasty for Ebstein anomaly or modified Maze operations, may develop areas of substantial intra-atrial block. Thus, identification of this phenomenon can aid in identifying optimal lead position within the diseased atrium.

Atrial tachyarrhythmias more frequently require an EPS, as an ablation procedure is often considered early in their management, especially for intraatrial reentrant tachycardia. (See “Invasive cardiac electrophysiology studies”.)

Management

It is important to recognize that in the management of atrial tachyarrhythmias in patients with congenital heart disease (CHD), rhythm versus rate control has not been studied. (See “Rhythm control versus rate control in atrial fibrillation”.) The AFFIRM and HOT-CAFÉ studies [44,45] did not include patients with congenital defects and repairs, and as such we do not have any long-term data comparing the outcomes with these strategies. In addition, the most common atrial arrhythmia encountered in clinical practice is that of intra-atrial re-entrant tachycardia [37], an arrhythmia that is unlikely to respond to rate-control because of the fixed circuit and slower atrial cycle length. For this reason, antiarrhythmic medications and ablation provide the cornerstone of therapy.

Acute termination — For any atrial tachyarrhythmia that is associated with hemodynamic instability, synchronized direct current (DC) cardioversion should be utilized without delay. (See “Basic principles and technique of cardioversion and defibrillation”.)

DC cardioversion can also be reserved for the initial management of hemodynamically stable yet symptomatic arrhythmias if a more definitive strategy has not yet been chosen, and the patient has fairly infrequent episodes. In this context, transesophageal echocardiography (TEE) to identify intracardiac clot is strongly recommended, especially in Fontan circulations, irrespective of the anticoagulation status. The classical Fontan often entails sluggish blood flow and atrial thrombus formation is common. Embolism of the thrombus into the pulmonary bed through DC cardioversion can be fatal in these patients. Cardioversion in the patient with congenital heart disease with appropriate anticoagulation, however, is proven to be safe and effective and should not be with-held [46].

Symptomatic bradyarrhythmias may require acute temporary pacing, and knowledge of intracardiac and vena caval anatomy is critical. Anticoagulation is recommended for any CHD patient with an intracardiac shunt receiving a temporary pacemaker to avoid systemic thromboembolism from the pacing lead, until a permanent epicardial system can be placed. (See “Temporary cardiac pacing”.)

Permanent pacemaker implantation — In general, the indications for permanent pacing in CHD (table 3) are similar to those in acquired heart disease. All symptomatic sinus or atrioventricular node disease requires pacemaker intervention [47]. (See “Permanent cardiac pacing: Overview of devices and indications”.)

Several considerations do exist for pacemaker implantation in patients with CHD. Lead access frequently poses difficulties in this group, and a detailed surgical history is vital, often with adjunctive venography or a preemptive TEE/bubble-study. In complex CHD patients with prior operative intervention in whom surgical reports are not available and urgent pacemaker placement is needed, imaging of venous anatomy with computerized tomography, magnetic resonance imaging, or venography can be pivotal.

To avoid thromboembolic stroke from lead thrombus, epicardial pacemaker placement is mandatory if any intracardiac shunt exists and is not amenable to closure [48-50]. In patients with a mechanical tricuspid/sub-pulmonic valve, the valve should not be crossed, and coronary sinus lead placement can be considered.

Antiarrhythmic drug therapy — Antiarrhythmic drugs (AADs) remain a cornerstone in the management of atrial arrhythmias in CHD patients. Class I agents (such as propafenone or flecainide) should be avoided in any patient with ventricular scar given the potential for life-threatening ventricular arrhythmias. [51-53]. (See “Arrhythmia management for the primary care clinician”.)

The most effective drug currently remains amiodarone, although significant side effects may be problematic leading to noncompliance or discontinuation [54]. (See “Major side effects of amiodarone” and “Clinical uses of amiodarone”.) Long-term use of amiodarone requires close monitoring of eye, thyroid, pulmonary, and hepatic function [55].

Dofetilide [55] and sotalol may be the safest alternate AADs in these patients [56]. (See “Therapeutic use and major side effects of sotalol” and “Therapeutic use of dofetilide”.)

Ablation — Catheter ablation is now utilized early in the course of many adult congenital patients with atrial tachyarrhythmias.

RFA can be complex and patients with CHD should be referred to experienced centers. Although early success rates are excellent even in the most complex defects [57], long-term recurrence rates remain suboptimal, especially when multiple circuits coexist and atrial scars are abundant [58]. The reentrant circuit can often be modified sufficiently to reduce symptomatic recurrence and improve antiarrhythmic drug therapy or pacing efficacy [59-61]. Older age at time of ablation and complexity of the atrial repair (Fontan or atrial-switch) both predict worse procedural success [62]. It is also important to recognize that the electrophysiological study often unmasks underlying sinus node dysfunction, and permanent pacing may be required [62]. For this reason, we recommend discussing this antecedently with patients.

Atrial fibrillation ablation with pulmonary vein isolation can also be considered in symptomatic patients refractory or unsuitable for long-term anti-arrhythmic therapy.

Atrial antitachycardia devices — Pacemakers with atrial antitachycardia pacing capability have been used to treat reentrant atrial tachycardias in patients with CHD. As a sole therapy, long-term efficacy for this approach is poor, but can be considered in patients with symptomatic bradycardia and/or other clear indications for pacing. In this setting, and often in conjunction with ablation, Maze, or anti-arrhythmic drug therapy, this pacing strategy can be effective in limiting symptomatic exacerbations [63,64].  

Maze surgery — CHD patients undergoing operative repair of a cardiac defect should be considered for maze surgery if there is a background of atrial arrhythmias [65]. Cut-and-sew techniques have more durable results with regard to freedom from atrial arrhythmia when compared with alternative energy sources such as radio-frequency ablation or cryoablation [66,67]. No data currently exist on preemptive maze surgery in CHD patients at high risk for, but without, prior documented arrhythmias. (See “Surgical ablation to prevent recurrent atrial fibrillation” and “Surgical ablation to prevent recurrent atrial fibrillation”, section on ‘Maze procedure’.)

Anticoagulation therapy — Anticoagulation therapy should be considered in CHD patients as soon as an atrial rhythm disturbance is identified. Patients with Fontan circulations or reduced right ventricular function have low flow states in the right heart and are at high risk of thrombus formation within the atria. Patients with repaired atrial septal defects also appear to be at considerable risk for thromboembolic complications in the setting of atrial arrhythmias, accounting for around one-fifth of late deaths in one series [14]. The use of conventional thromboembolic and hemorrhagic risk-assessment scores, such as CHA₂DS₂-VASc and HAS-BLED, has not been rigorously evaluated in these patient groups, yet it does seem reasonable to use as a surrogate guide until the results of larger registry studies become available [68]. The newer oral anticoagulant agents such as dabigatran, rivaroxaban, and apixaban have also not been specifically studied in CHD patients. (See “Atrial fibrillation: Anticoagulant therapy to prevent embolization” and “Atrial fibrillation: Risk of embolization”.)

SPECIFIC CONSIDERATIONS

Accessory pathways and Ebstein’s anomaly — Ebstein’s anomaly encompasses a wide spectrum of maldevelopment of the tricuspid valve, variable but often marked right atrial dilatation, and underdeveloped right ventricular function. Accessory pathways are present in at least one-fifth of patients with Ebstein’s anomaly [69], are almost always right-sided (or concordant with the side of Ebstein valve in case of transposition) and may be multiple [70-73]. Catheter ablation is highly effective in eliminating these accessory pathways and should be considered as first-line therapy. (See “Ebstein’s anomaly of the tricuspid valve” and “Anatomy, pathophysiology and localization of accessory pathways in the preexcitation syndrome” and “Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway”.)

Atrial arrhythmias that conduct rapidly to the ventricle via the accessory pathway may cause hemodynamic deterioration, syncope and even death. The presence of an accessory pathway in any patient has also been strongly linked to the development of atrial fibrillation [74], and the ablation of the pathway often results in quiescence of the atrial arrhythmia [75]. However, macro-reentrant atrial flutters in the context of postoperative CHD will not be ameliorated by accessory pathway ablation. More importantly, ablation of accessory pathways in these patients is critical as pre-excited atrial fibrillation or atrial flutter can be fatal [74]. Therefore, the approach to these patients should be to initially remove the accessory pathway so that the risk of sudden death has decreased significantly and then address the remaining atrial arrhythmias.

ASD — Atrial septal defect (ASD) is one of the most common congenital cardiac anomalies, and is associated with a high incidence of atrial arrhythmias, which increase in frequency as these patient age [7,14]. (See “Indications for closure and medical management of atrial septal defects in adults”.)

The later in life the ASD is repaired, the more likely atrial arrhythmias are to develop, while closure does not appear to mitigate the development of this problem [14]. In addition, significant thromboembolic complications have been observed in patients who had surgical ASD closure performed at age 24 years of age or older, affecting around 22 percent of these patients [14]. For this reason, anticoagulation is mandatory for all patients with atrial fibrillation following ASD closure. Atrial fibrillation should be actively sought using Holter monitoring. Intraatrial reentrant tachycardia circuits around a patch or suture lines also occur frequently and ablative therapy should be considered early in their management [76]. Anticoagulation is also recommended for this arrhythmia. (See ‘Ablation’ above.)

Prior Maze — Modified Maze operations are a common, safe and highly effective surgical method of restoring sinus rhythm in patients with CHD and atrial fibrillation/flutter. (See “Surgical ablation to prevent recurrent atrial fibrillation”.)

These interventions, which are often performed at the time of CHD operations, can be effective in preventing atrial arrhythmia recurrence approximately 90 and 80 percent at 1 and 10 years, respectively [77]. Patients with prior maze procedures can develop breakthrough atrial tachyarrhythmias at points of incomplete atrial block; this is less common with traditional cut-and-sew maze procedures than with open surgical radio-frequency or cryotherapy approaches [66].

The Maze procedure is not free of complications; the extensive transmural lesions not only potentially interfere with sinus and intraatrial conduction [78], but likely also disrupt atrial innervation. Sinus node dysfunction, atrial bradyarrhythmias and tachyarrhythmias, inappropriate heart rate responses to activity, and pacemaker implantation are not uncommon sequelae of the Maze procedure [79]. New atrial tachyarrhythmias can develop around Maze lesions, and ablation of these can also be undertaken. Frequently antiarrhythmic drug therapy is relied on in this context, and atrial antitachycardia pacemakers can be of added utility [80].

Tetralogy of Fallot — Bradyarrhythmias requiring permanent pacing in patients with tetralogy of Fallot are uncommon. However, atrial tachyarrhythmias are a frequent cause of morbidity and may be seen in up to 25 percent of TOF patients [15]. (See “Management and outcome of tetralogy of Fallot”.) The prevalence of atrial fibrillation markedly increases after 45 years of age in this group and in those with reduced left ventricular function [81].

Fontan procedure — Fontan procedures that utilize right atrial tissue as part of the conduit are frequently associated with the development of late atrial arrhythmias [82]. In a retrospective analysis of adult patients with prior Fontan (mean follow-up of 18.6 years), 42 percent suffered at least one tachyarrhythmia [83]. The most common arrhythmia was intra-atrial re-entrant tachycardia.

The development of an automatic tachycardia in this context should raise suspicion for an underlying hemodynamic issue, but often this mechanism can only be definitively determined with cardiac catheterization and electrophysiological study. A detailed look for obstruction in the Fontan circuit and/or AV valve regurgitation [30] should be undertaken. Conversion to an extracardiac conduit or total cavopulmonary connection may provide hemodynamic relief and improve the arrhythmia burden [84].

Injury to the sinus node is also common following the Fontan procedure [85].

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, “The Basics” and “Beyond the Basics.” The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on “patient info” and the keyword(s) of interest.)

●Basics topics (see “Patient information: Heart block in adults (The Basics)” and “Patient information: Heart block in children (The Basics)”)

SUMMARY AND RECOMMENDATIONS

●Atrial arrhythmias are common in congenital heart disease (CHD), affecting at least 20 percent of individuals with CHD over their lifetime. (See ‘Prevalence and incidence’ above.)

●Atrial arrhythmias are a major cause of morbidity in patients with CHD and can be precipitated by cardiac residua. They can also cause hemodynamic deterioration. For this reason, it is imperative that a good hemodynamic assessment be undertaken as part of the initial work-up. (See ‘Prevalence and incidence’ above and ‘Evaluation’ above.)

●CHD patients with atrial arrhythmias should be referred to centers that routinely follow this population, as recommended in the 2015 American Heart Association scientific statement on “Congenital heart disease in the older adult” [86].

●Bradycardia can be inherent to the CHD anomaly; however, it is more commonly seen secondary to operative disruption of these structures. This can occur in both the early postoperative period or later due to fibrosis. (See ‘Bradycardias’ above.)

●Stroke is common in this group, and atrial arrhythmias such as atrial fibrillation and intraatrial reentrant tachycardia should prompt the clinician to consider long-term oral anticoagulation based on the CHA₂DS₂-VASc risk schema. (See ‘Anticoagulation therapy’ above.)

●In general, the indications for permanent pacing in CHD are similar to those in acquired heart disease. All symptomatic sinus or atrioventricular node disease requires pacemaker intervention. (See ‘Permanent pacemaker implantation’ above.)