Arrhythmias in patients with congenital heart disease

Improved surgical outcome for patients with congenital heart disease (CHD) has created a rapidly expanding population of adolescents and young adult survivors. Cardiac arrhythmias are a common late sequelae of this form of heart disease. Effective treatment requires clear understanding of the underlying anatomic defect as well as the specific surgical interventions. Intraatrial reentrant tachycardia (IART) is the most common and difficult arrhythmia encountered in these patients. Traditional IART treatment with medication has been largely unsuccessful, but radiofrequency ablation has emerged in recent years as a promising option for many patients. The availability of three-dimensional mapping systems and irrigated-tip ablation catheters has improved acute success rates for IART to better than 90%. Postablation recurrence of IART still remains problematic for patients who have undergone the Fontan operation, in which case atrial maze surgery may be considered. Ventricular tachycardia (VT) is seen in a smaller number of CHD patients, most notably those with tetralogy of Fallot or aortic stenosis. The adoption of implantable defibrillator (ICD) therapy for these patients has improved outcome. Owing to their complex anatomy, the CHD population presents unique challenges during both catheterization and device implant. Multicenter study of this unique patient group is needed in order to develop more objective treatment guidelines.     

Arrhythmias after surgery for congenital heart disease

The improvement of surgical techniques over the last few years have made postoperative chronotropic insufficiency either by sinus node dysfunction or iatrogenic atrioventricular block less common. However, reentrant tachycardia around lines of incision or a patch may be observed. Persistent dilatation of a cardiac chamber or ventricular dysfunction are predisposing factors. Flutter-like arrhythmias occur mainly after atrial surgery (closure of atrial septal defects, Mustard, Senning or Fontan procedures). Ventricular tachycardias are observed more often after correction of tetralogy of Fallot or in patients with severe ventricular dysfunction. In fact, any type of arrhythmia may arise, especially when the lesion is operated late in childhood or in adulthood with a partial haemodynamic result (residual gradient, valvular regurgitation or ventricular dysfunction...). In this context, regular ECG follow-up should be associated with repeated Holter monitoring and exercise stress testing. From the therapeutic point of view, amiodarone remains the best antiarrhythmic drug. Radiofrequency ablation techniques represent a recent but decisive advance in the management of atrial arrhythmias.     

The right heart in congenital heart disease

The clinical presentation of right ventricular (RV) dysfunction due to congenital heart disease (CHD) is similar to that of cor pulmonale. RV volume and pressure loads, and primary RV myocardial dysfunction are mechanisms by which CHD affects right heart function. RV volume load may arise from pre-tricuspid left to right shunts (e.g., atrial septal defect) or regurgitant lesions in the right heart (e.g., Ebstein's anomaly of the tricuspid valve and pulmonary insufficiency after repair of tetralogy of Fallot). RV pressure load may be caused by anatomic obstruction to RV outflow and by pulmonary arteriolar hypertension. The latter can result from Eisenmenger syndrome secondary to congenital and postoperative left to right shunts or from defects that cause pulmonary venous hypertension (e.g., pulmonary vein stenosis, cor triatriatum, or mitral stenosis). The RV myocardium may be affected by a primary cardiomyopathy or by congenital abnormalities of the coronary vessels. Finally, CHD may be associated with airway obstruction, scoliosis, or pulmonary emboli, which, in turn, may lead to the development of cor pulmonale. Congenital heart disease, therefore, must be included in the differential diagnosis of patients who present with right ventricular dysfunction.     

Arrhythmias in heart failure

Opinion statement  

Indications for heart transplantation in congenital heart disease

In this review we have looked at indications for cardiac transplantation in congenital heart disease. An outline of the general principles of the use of transplant as a management strategy both as a first line treatment and following other surgical interventions is discussed. We explore the importance of the timing of patient referral and the evaluations undertaken, and how the results of these may vary between patients with congenital heart disease and patients with other causes of end-stage heart failure. The potential complications associated with patients with congenital heart disease need to be both anticipated and managed appropriately by an experienced team. Timing of transplantation in congenital heart disease is difficult to standardize as the group of patients is heterogeneous. We discuss the role and limitations of investigations such as BNP, 6 minute walk, metabolic exercise testing and self estimated physical functioning. We also discuss the suitability for listing. It is clear that congenital heart patients should not be considered to be at uniform high risk of death at transplant. Morbidity varies greatly in the congenital patient population with the failing Fontan circulation having a far higher risk than a failing Mustard circulation. However the underlying issue of imbalance between donor organ supply and demand needs to be addressed as transplant teams are finding themselves in the increasingly difficult situation of supporting growing numbers of patients with a diverse range of pathologies with declining numbers of donor organs.     

Arrhythmias in heart failure

Abstracts

Arrhythmias in heart failure     

Three-dimensional echocardiography in congenital heart disease

Matrix array technology has brought three-dimensional echocardiography into the clinical practice of cardiology. Arguably, this advancement is most notable in the field of pediatric cardiology. Full-volume acquisitions now can be undertaken in the youngest of infants with excellent image quality. This article illustrates the clinical application of three-dimensional echocardiography in congenital heart disease.     

Interventional catheterization in congenital heart disease

Balloon dilation is now an established treatment for many congenital heart defects. Recent papers deal with the extension of this approach to more complex anomalies, such as tetralogy of Fallot and transposition of the great arteries; the results are variable. Another area of investigation is balloon valvoplasty in more contentious settings, such as neonatal aortic stenosis. The catheter method appears to be as effective as surgery in these cases. Attention has also been directed to the determinants of success or failure in, for example, aortic recoarctation. Here, as in aortic stenosis, basic anatomy plays an important role. Catheter closure procedures also figure in the literature. Closure of persistent ductus now appears to be established everywhere except in the United States. Also of interest are early reports of the "button device" for closure of atrial septal defects. The use of stents appears to offer effective treatment for peripheral pulmonary stenosis, a condition with disappointing results from surgery and balloon angioplasty. Stents may also offer an alternative method for long-term maintenance of duct patency. Catheter interventions now constitute a major part of the work of pediatric cardiologists, and the present status has been summarized in the past year.     

Endovascular stents in congenital heart disease

Acquired or de novo vascular obstructions can adversely affect the outcomes of management algorithms for children with congenital heart lesions. Although surgical repair is frequently feasible, some acquired or congenital obstructions are difficult to address in the operating theater. Presented is the recent experience with endovascular stents to relieve such stenoses, and their impact on patient care.     

Embolisation procedures in congenital heart disease

Eight therapeutic embolisation procedures were performed by the transcutaneous catheter technique in seven patients with congenital heart disease. After surgical correction of tetralogy of Fallot (four patients), catheter embolisation was used to occlude two large aortopulmonary collaterals (one patient), three small aortopulmonary collaterals (one patient), and two Blalock-Taussig shunts (two patients). In two patients congenital coronary anomalies were occluded--a coronary arteriovenous malformation and a coronary artery/bronchial artery anastomosis. In one patient a pulmonary arteriovenous malformation was embolised. Detachable balloons were used to occlude six large arteries, the three small arteries were occluded with small gelfoam fragments, and the pulmonary arteriovenous malformation was occluded with multiple steel coils and large gelfoam pieces. Successful occlusion was achieved in all cases. No complications were encountered and the procedure was well tolerated even in the two patients receiving postoperative intensive care. Therapeutic embolisation in suitable cases is a safe and effective alternative to surgery and the detachable balloon technique is effective in occluding high flow vessels.