Double outlet ventricles: review of anatomic and imaging characteristics.

Hearts with double outlet ventricles and concordant atrioventricular connections account for about 1%-3% of all cases of congenital heart disease. We review hearts with two ventricles and concordant atrioventricular connections with double outlet right ventricle (DORV), double outlet left ventricle (DOLV) and double outlet both ventricles (DOBV) from the morphological and clinical imaging perspectives. These hearts are a heterogeneous group of congenital cardiac malformations with a wide range of pathophysiologies that require an individualised surgical approach based on a precise understanding of the complex cardiovascular anatomy. Owing to their differing temporal, spatial and contrast resolutions, we propose that multimodality imaging provides optimal characterisation of various intracardiac morphological features of double outlet hearts. This approach aids clinical diagnosis for optimising treatment options across these malformations.

Electrocardiographic landmarks of idiopathic ventricular arrhythmia origins.

Idiopathic ventricular arrhythmias occur in the absence of underlying structural heart disease and less commonly in the presence of coexistent, but mechanistically unrelated, myocardial scar. These arrhythmias originate from several anatomical sites in both ventricles, with a predilection in outflow tract structures. The 12-lead surface ECG is the initial mapping tool, which is widely used to identify their origin. Specific features can predict the site of idiopathic ventricular arrhythmias, thus differentiating right from left ventricular, as well as endocardial from epicardial origins. In this review, we aim to analyse electrocardiographic landmarks for determination of idiopathic ventricular arrhythmia sources, with specific emphasis on pertinent caveats and anatomical relationships.

Experimental, Pathologic, and Clinical Findings of Radiofrequency Catheter Ablation of Para-Hisian Region From the Right Ventricle in Dogs and Humans.

BACKGROUND: Ablation of para-Hisian accessory pathway (AP) poses high risks of atrioventricular block. We developed a pacing technique to differentiate the near-field (NF) from far-field His activations to avoid the complication. METHODS AND RESULTS: Three-dimensional mapping of the right ventricle was performed in 15 mongrel dogs and 23 patients with para-Hisian AP. Using different pacing outputs, the NF- and far-field His activation was identified on the ventricular aspect. Radiofrequency application was delivered at the NF His site in 8 (group 1) and the far-field His site in 7 dogs (group 2), followed by pathologic examination after 14 days. NF His activation was captured with 5 mA/1 ms in 10 and 10 mA/1 ms in 5 dogs. In group 1, radiofrequency delivery resulted in complete atrioventricular block in 3, right bundle branch block with HV (His-to-ventricular) interval prolongation in 1, and only right bundle branch block in 2 dogs, whereas no changes occurred in group 2. Pathologic examination in group-1 dogs showed complete or partial necrosis of the His bundle in 4 and complete necrosis of the right bundle branch in 5 dogs. In group 2, partial necrosis in the right bundle branch was found only in 1 dog. Using this pacing technique, the APs were 5.7±1.2 mm away from the His bundle located superiorly in 20 or inferiorly in 3 patients. All APs were successfully eliminated with 1 to 3 radiofrequency applications. No complications and recurrence occurred during a follow-up of 11.8±1.4 months. CONCLUSIONS: Differentiating the NF His from far-field His activations led to a high ablation success without atrioventricular block in para-Hisian AP patients.

[Arrhythmia in adults with congenital heart defects : Atrial tachycardia]. / Arrhythmien bei Erwachsenen mit angeborenen Herzfehlern : Atriale Tachykardien.

Atrial arrhythmias are frequently encountered in patients with congenital heart disease (CHD) with or without corrective surgery and respond to pharmacological therapies with only limited success. This review describes the technologies currently available for performing successful ablation procedures in this very complex patient cohort. In addition to an understanding of the underlying anatomy, which can be supplemented by 3D imaging with the aid of magnetic resonance imaging (MRI) or computed tomography (CT), the choice between the different 3D mapping systems (sequential versus simultaneous) is presented. Finally, conventional manual navigation is compared with magnetic navigation and then discussed with regard to the respective arrhythmias encountered with the different forms of CHD.

Manifestations of coronary arterial injury during catheter ablation of atrial fibrillation and related arrhythmias.

BACKGROUND: The prevalence and clinical consequences of coronary arterial injury in a large series of patients undergoing radiofrequency ablation (RFA) of atrial fibrillation (AF) are unknown. OBJECTIVE: The purpose of this study was to describe the frequency and clinical consequences of coronary arterial injury in a large series of patients undergoing catheter ablation of AF and postablation atrial tachycardia. METHODS: The medical records of 5,709 consecutive patients undergoing RFA of AF were reviewed. Heart specimens were also dissected to analyze the course of the coronary arteries. RESULTS: Arterial injury occurred in 8 patients (0.14%). Three patients developed ventricular fibrillation (VF) due to occlusion of the distal or proximal circumflex (Cx) artery related to RFA in the distal coronary sinus (CS) or base of the LA appendage, respectively. Two VF patients underwent stenting. Five patients developed acute sinus node (SN) dysfunction. In 4/5 patients, the culprit site was subjacent to the SN artery (per computed tomography) coursing over the anterior LA (n = 3) or the septal RA (n = 1). Two patients required a permanent pacemaker. In the heart specimens, the SN artery, after its origin from the proximal Cx artery, coursed along the anterior LA. Also, the proximal Cx artery was found in the atrioventricular groove underneath the base of the LA appendage. CONCLUSION: Clinically apparent injury to the coronary arteries during LA ablation for AF is rare. However, it may be associated with potentially life-threatening ventricular arrhythmias and acute SN dysfunction requiring permanent pacing. The culprit sites seem to be in the distal coronary sinus and the anterior LA, and correlate well with the course of the coronary arteries in pathologic specimens. Vigilance and low-power settings are important in minimizing the risk of arterial injury.

Pharmacological and non-pharmacological therapy for arrhythmias in the pediatric population: EHRA and AEPC-Arrhythmia Working Group joint consensus statement.

In children with structurally normal hearts, the mechanisms of arrhythmias are usually the same as in the adult patient. Some arrhythmias are particularly associated with young age and very rarely seen in adult patients. Arrhythmias in structural heart disease may be associated either with the underlying abnormality or result from surgical intervention. Chronic haemodynamic stress of congenital heart disease (CHD) might create an electrophysiological and anatomic substrate highly favourable for re-entrant arrhythmias. As a general rule, prescription of antiarrhythmic drugs requires a clear diagnosis with electrocardiographic documentation of a given arrhythmia. Risk-benefit analysis of drug therapy should be considered when facing an arrhythmia in a child. Prophylactic antiarrhythmic drug therapy is given only to protect the child from recurrent supraventricular tachycardia during this time span until the disease will eventually cease spontaneously. In the last decades, radiofrequency catheter ablation is progressively used as curative therapy for tachyarrhythmias in children and patients with or without CHD. Even in young children, procedures can be performed with high success rates and low complication rates as shown by several retrospective and prospective paediatric multi-centre studies. Three-dimensional mapping and non-fluoroscopic navigation techniques and enhanced catheter technology have further improved safety and efficacy even in CHD patients with complex arrhythmias. During last decades, cardiac devices (pacemakers and implantable cardiac defibrillator) have developed rapidly. The pacing generator size has diminished and the pacing leads have become progressively thinner. These developments have made application of cardiac pacing in children easier although no dedicated paediatric pacing systems exist.

[Structural features of the sinus of valsalva and the proximal portion of the coronary arteries: their relevance to retrograde aortocoronary dissection]. / Características estructurales de los senos de Valsalva y porción proximal de las arterias coronarias. Su relevancia durante la disección retrógrada aortocoronaria.

INTRODUCTION AND OBJECTIVES: Retrograde aortocoronary dissection is an unusual complication of coronary angioplasty. Our study provides new structural details of the aortic sinuses and the proximal portions of the coronary arteries, which enable better understanding of several clinical features associated with this complication. METHODS: We studied eight aortic sinus specimens from patients with structural ischemic heart disease using dissection, histologic analysis, and scanning electron microscopy, and compared findings with those in eight control specimens. RESULTS: We observed the following features: a) in 10 specimens (71%), the left coronary artery diameter was greater than the right; b) the angle that the ascending aorta made with the left coronary artery was acute, whereas that with the right coronary artery was closer to a right angle, thereby possibly providing a better approach for catheterization; c) in contrast to those of the right coronary artery, the periostial wall and sinotubular junction of the left coronary artery were formed by more smooth muscle cells and by a dense matrix of collagen type-I fibers, and d) the aortic sinuses and coronary arteries in structural ischemic heart disease specimens displayed structural alterations that affected the aortic tunica media and the collagen distribution at the sinotubular junction. CONCLUSIONS: The morphological and structural differences observed between right and left sides suggest that the left aortic sinus is more resistant to traction and is, therefore, less prone to iatrogenic dissection. Structural ischemic heart disease is a risk factor that increases the likelihood of aortocoronary dissection.

The implications for fetal outcome of an abnormal arrangement of the abdominal vessels.

In a prospective audit of consecutive referrals for fetal echocardiography between 1997 and 2003, we documented all instances of an abnormal arrangement of the abdominal vessels. We then established the structure of the heart in these fetuses, noting any extra-cardiac associations, and the eventual outcomes. We found a cardiac abnormality in 572 of the 2,136 fetuses examined during this period (27 percent), with 16 (0.8 percent) having an abnormal arrangement of the abdominal great vessels. Mirror-imaged arrangement was found in 3, while the arrangement suggested right isomerism in 6, and left isomerism in 7. Of these 16 fetuses, 14 had cardiac malformations. Isomerism of the right atrial appendages was found in 7 fetuses, all with either a right-sided stomach or cardiac apex, and 6 with a common atrioventricular junction guarded by a common valve. Only 1 of these fetuses survived. Of the 3 fetuses with mirror-imaged abdominal great vessels, 2 also had mirror-imaged atrial arrangement, while the 3rd had isomeric right appendages. Only one of 7 fetuses with an abdominal great vein posterior to the aorta had bilateral left atrial appendages. The remaining 6 had usual atrial arrangement, with normal pulmonary venous connections in all but one, who had infra-diaphragmatic totally anomalous pulmonary venous connection. Of these fetuses, 2 had coarctation of the aorta, and 2 others had complex cardiac malformations resulting in neonatal death. One died in childhood from biliary atresia, and three are alive. Abnormal arrangements of the abdominal great vessels, therefore, were found in 0.8 percent of our total fetuses, and in 2.4 percent of those with cardiac malformations. Those with an abnormal arrangement of the abdominal vessels combined with an abnormal arrangement of the atrial appendages, however, made up only 0.5 percent and 1.6 percent, respectively. While screening for an abnormal arrangement of the abdominal vessels overestimated the incidence of left, but not right, isomerism of the atrial appendages, it did predict the presence of important extra-cardiac malformations that required urgent recognition and management after birth.

[Anatomy of cardiac nodes and atrioventricular specialized conduction system]. / Anatomía de los nodos cardíacos y del sistema de conducción específico auriculoventricular.

Concomitant with the development of catheter ablation techniques for the treatment of atrial arrhythmias, there has been renewed interest in the morphologic arrangement of the cardiac conduction system. The first descriptions of the anatomy of the nodes and atrioventricular conduction system appeared nearly 100 years ago. Since then the subject has been controversial, possibly because of the early researchers' imprecise knowledge of histology. The components and structure of the specific conduction system in humans are similar to those found in commonly used laboratory animals. The conduction system is composed of specialized myocytes. Its atrial components, the sinus node and the atrioventricular node, are in contact with atrial myocardium. The His bundle penetrates the right fibrous trigone, then divides into two specialized ventricular bundle branches (right and left), which also are surrounded by a fibrous sheath that separates the specialized myocytes from the ordinary myocardium. Only at the distal ramifications of the bundle branches do the fibrous sheaths disappear, allowing continuity with the ventricular myocardium. Knowledge of the specialized myocardium can help in the development of potentially useful therapies for some forms of cardiac arrhythmia.