Barbara J. Deal

AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society: endorsed by the International Society for Computerized Electrocardiology.

The present article introduces the second part of “Recommendations for Standardization and Interpretation of the Electrocardiogram.” The project was initiated by the Council on Clinical Cardiology of the American Heart Association and has been endorsed by the American College of Cardiology

Recommendations for Physical Activity and Recreational Sports Participation for Young Patients With Genetic Cardiovascular Diseases

A group of relatively uncommon but important genetic cardiovascular diseases (GCVDs) are associated with increased risk for sudden cardiac death during exercise, including hypertrophic cardiomyopathy, long-QT syndrome, Marfan syndrome, and arrhythmogenic right ventricular cardiomyopathy. These conditions, characterized by diverse phenotypic expression and genetic substrates, account for a substantial proportion of unexpected and usually arrhythmia-based fatal events during adolescence and young adulthood. Guidelines are in place governing eligibility and disqualification criteria for competitive athletes with these GCVDs (eg, Bethesda Conference No. 26 and its update as Bethesda Conference No. 36 in 2005). However, similar systematic recommendations for the much larger population of patients with GCVD who are not trained athletes, but nevertheless wish to participate in any of a variety of recreational physical activities and sports, have not been available. The practicing clinician is frequently confronted with the dilemma of designing noncompetitive exercise programs for athletes with GCVD after disqualification from competition, as well as for those patients with such conditions who do not aspire to organized sports. Indeed, many asymptomatic (or mildly symptomatic) patients with GCVD desire a physically active lifestyle with participation in recreational and leisure-time activities to take advantage of the many documented benefits of exercise. However, to date, no reference document has been available for ascertaining which types of physical activity could be regarded as either prudent or inadvisable in these subgroups of patients. Therefore, given this clear and present need, this American Heart Association consensus document was constituted, based largely on the experience and insights of the expert panel, to offer recommendations governing recreational exercise for patients with known GCVDs.

AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram. Part III: Intraventricular Conduction Disturbances A Scientific Statement From the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society

The present article is the fourth in a series of 6 documents focused on providing current guidelines for the standardization and interpretation of the electrocardiogram (ECG). The project was initiated by the Council on Clinical Cardiology of the American Heart Association. The rationale for this project and the process for its implementation were described earlier.1 Abnormalities in the ST segment, T wave, and duration of the QT interval reflect abnormalities in ventricular repolarization. These abnormalities are common and often difficult to interpret. The U wave most likely represents an electricmechanical phenomenon that occurs after repolarization is completed. However, it is frequently included in discussions of repolarization and is discussed in this section. The ST segment corresponds to the plateau phase of the ventricular transmembrane action potential. Under normal conditions, the transmembrane voltage changes slowly during this phase and remains at approximately the same level in all ventricular myocardial cells. As a result, only small voltage gradients are present. This absence of pronounced voltage gradients is similar to that which occurs during electric diastole, ie, from the end of repolarization to the onset of the next depolarization, when ventricular myocardial cells are at their resting transmembrane potential of approximately 85 mV. This corresponds to the TP segment on the ECG. The absence of significant voltage gradients in ventricular myocardial cells during these 2 phases of the cardiac cycle explains why the ST and TP segments are normally nearly flat and at approximately the same level; that is, they are isoelectric. The T wave corresponds to the phase of rapid ventricular repolarization (phase 3) of the ventricular action potential.

Radiofrequency Catheter Ablation for Tachyarrhythmias in Children and Adolescents

Background Although radiofrequency catheter ablation has been used extensively to treat refractory supraventricular tachycardia in adults, few data are available on its safety and efficacy in children and adolescents. We reviewed registry data obtained from 24 centers to evaluate the indications, early results, complications, and short-term follow-up data in young patients who underwent this procedure. Methods Standardized data were submitted for 652 patients who underwent 725 procedures between January 1, 1991, and September 1, 1992. The mean length of follow-up was 13.5 months. Results The median age of the patients was 13.5 years, and 84 percent of them had structurally normal hearts. The initial success rates for ablation of atrioventricular accessory pathways (508 of 615 procedures) and atrioventricular-node reentry (63 of 76 procedures) were both 83 percent. Greater institutional experience in performing ablation in children and location of the accessory pathway in the left free wall correlated with...

Supraventricular tachycardia mechanisms and their age distribution in pediatric patients

To better define the natural history of supraventricular tachycardia (SVT) in young patients, age distribution of SVT mechanisms was examined in 137 infants, children and adolescents. Patients with a history of cardiac surgery or neuromuscular diseases were excluded. An electrophysiologic study was performed in each patient: transesophageal (110 patients) or transvenous (14 patients) or both (13 patients). Mechanisms were classified as SVT using accessory atrioventricular (AV) connection (SVT using accessory connection, including orthodromic and antidromic reciprocating tachycardia), primary atrial tachycardia (including chaotic, automatic and reentrant atrial tachycardia), and tachycardia due to reentry within the AV node. SVT using accessory connection occurred in 100 of 137 patients (73%) and was the most prevalent mechanism. Primary atrial tachycardia and reentry within the AV node were present in 19 of 137 (14%) and 18 of 137 (13%) patients, respectively. Using a multinomial logit model, relative probabilities for tachycardia mechanisms for 5 age groups--prenatal, less than 1, 1 to 5, 6 to 10 and greater than 10 years--were determined. Primary atrial tachycardia (11 to 16%) and SVT using accessory connection (58 to 84%) appeared throughout infancy, childhood and adolescence. On the other hand, tachycardia due to reentry within the AV node (0 to 31%) rarely appeared before age 2 years. Mechanisms of SVT appear to have age-dependent distributions. SVT using accessory connection is the most common mechanism in young patients. We speculate that the propensity to tachycardia due to reentry within the AV node occurs during postnatal development.

Hypoplastic Left Heart Syndrome : Current Considerations and Expectations

In the recent era, no congenital heart defect has undergone a more dramatic change in diagnostic approach, management, and outcomes than hypoplastic left heart syndrome (HLHS). During this time, survival to the age of 5 years (including Fontan) has ranged from 50% to 69%, but current expectations are that 70% of newborns born today with HLHS may reach adulthood. Although the 3-stage treatment approach to HLHS is now well founded, there is significant variation among centers. In this white paper, we present the current state of the art in our understanding and treatment of HLHS during the stages of care: 1) pre-Stage I: fetal and neonatal assessment and management; 2) Stage I: perioperative care, interstage monitoring, and management strategies; 3) Stage II: surgeries; 4) Stage III: Fontan surgery; and 5) long-term follow-up. Issues surrounding the genetics of HLHS, developmental outcomes, and quality of life are addressed in addition to the many other considerations for caring for this group of complex patients.

Wolff-Parkinson-White syndrome and supraventricular tachycardia during infancy: Management and follow-up

The records of 90 patients with Wolff-Parkinson-White syndrome who presented with supraventricular tachycardia in the first 4 months of life were reviewed. Among these, 63% were male. Structural heart disease was present in 20%, most commonly Ebsteins anomaly. All patients presented with a regular narrow QRS tachycardia, and pre-excitation became evident only when normal sinus rhythm was established. Only one infant had atrial flutter and none had atrial fibrillation. Type A Wolff-Parkinson-White syndrome was most common (49%), with heart disease occurring in only 5% of these patients. In contrast, heart disease was identified in 45% of those with type B syndrome. Initially, normal sinus rhythm was achieved in 88% of the 66 infants treated with digoxin with no deaths. Normal sinus rhythm resumed after electrical countershock in 87% of the 15 infants so treated. Maintenance digoxin therapy was used in 85 patients. The Wolff-Parkinson-White pattern disappeared in 36% of the patients. Four infants died of cardiac causes during the mean follow-up period of 6.5 years. Two of these four infants had congenital heart disease; the third, with a normal heart initially, developed ventricular fibrillation and died from a cardiomyopathy considered related to resuscitation. The remaining infant, with a normal heart, died suddenly at 1 month of age. All were receiving digoxin. A wide QRS tachycardia later appeared in three patients, all with heart disease, one of whom died.(ABSTRACT TRUNCATED AT 250 WORDS)

AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram Part V: Electrocardiogram Changes Associated With Cardiac Chamber Hypertrophy: A Scientific Statement From the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society: Endorsed by the International Society for Computerized Electrocardiology

This is the sixth and final section of the project to update electrocardiography (ECG) standards and interpretation. The project was initiated by the Council on Clinical Cardiology of the American Heart Association (AHA). The rationale for the project and the process for its implementation were described in a previous publication.1 The ECG is considered the single most important initial clinical test for diagnosing myocardial ischemia and infarction. Its correct interpretation, particularly in the emergency department, is usually the basis for immediate therapeutic interventions and/or subsequent diagnostic tests. The ECG changes that occur in association with acute ischemia and infarction include peaking of the T waves, referred to as hyperacute T-wave changes, ST-segment elevation and/or depression, changes in the QRS complex, and inverted T waves. The ST-segment changes are produced by the flow of currents, referred to as “injury currents,” that are generated by the voltage gradients across the boundary between the ischemic and nonischemic myocardium during the resting and plateau phases of the ventricular action potential, which correspond to the TQ and ST segments of the ECG.2,3 Current guidelines suggest that when these ST-segment shifts reach

Ventricular arrhythmias in postoperative tetralogy of Fallot.

Ventricular arrhythmias in patients after total surgical repair of tetralogy of Fallot have been associated with late sudden death. In this large multicenter retrospective study of 359 patients with postoperative tetralogy of Fallot, spontaneous ventricular premature complexes (VPCs) on 24-hour ambulatory electrocardiographic monitoring and laboratory-induced ventricular tachycardia (VT) by electrophysiologic stimulation were analyzed. The mean age at surgical repair was 5 years and the mean follow-up duration after repair was 7 years. Spontaneous VPCs on ambulatory monitoring were found in 48% and induced VT on electrophysiologic stimulation was found in 17% of patients. Both spontaneous VPCs and induced VT were significantly related to delayed age at repair, longer follow-up interval, symptoms of syncope or presyncope and right ventricular systolic hypertension (greater than 60 mm Hg) (p less than 0.05), but not to right ventricular diastolic pressure greater than 8 mm Hg. The VPCs on ambulatory monitoring were more complex with increasing age at repair and follow-up duration. Induction of VT on electrophysiologic stimulation correlated with spontaneous VPCs including VT on 24-hour ambulatory electrocardiographic monitoring. The electrophysiologic stimulation protocol varied and the induction of VT increased with a more aggressive stimulation protocol. While induced sustained monomorphic VT was related to all forms of spontaneous VPCs, induced nonsustained polymorphic VT was related to more complex forms of VPCs on ambulatory monitoring. VT was not induced in asymptomatic patients who had normal 24-hour ambulatory electrocardiographic monitoring and normal right ventricular systolic pressure. (ABSTRACT TRUNCATED AT 250 WORDS)

NASPE expert consensus conference: Radiofrequency catheter ablation in children with and without congenital heart disease. Report of the writing committee

A Consensus Conference on Pediatric Radiofrequency Catheter Ablation took place at the 21 Annual Scientific Sessions of the North American Society of Pacing and Electrophysiology (NASPE). The participants included health professionals from the pediatric and adult electrophysiological communities, and involved physicians, nurses, and other allied professionals. This statement attempts to coalesce the information presented and is directed to all health professionals who are involved in the care of pediatric patients undergoing ablation. In an attempt to write such a document, the editors must try to represent what they believed was the general consensus of opinion amongst the participants. As generally understood in the medical world, “consensus” does not indicate complete harmony within a group but a substantial degree of agreement. It is hoped that the information presented falls within that definition and will serve as a foundation on which to build toward in the future. Even as this document was being prepared, new technologies were introduced that may expand the indications and possibly the type of personnel and training necessary to perform these procedures. It will be interesting to look back on this statement of the current state-of-the art over the next 5–10 years and see if some of the recommendations stand the test of time. As is true of many documents, only in retrospect can a judgement be made on the strength of what is stated in this statement. The goal of the Consensus Conference was to bring together pediatric and adult practitioners in electrophysiology for an all day discussion of catheter ablation in children and in patients with congenital heart disease (CHD). The organizers believed that, in choosing topics for discussion, the development of indications for catheter ablation should flow naturally from what is known concerning the natural history of the arrhythmias in question in the pediatric population and from the latest information available concerning outcomes from these procedures. Therefore, the initial part of this statement deals with the natural history issues of specific arrhythmias in children with and without CHD. Issues of radiation exposure and animal models of toxicity due to radiofrequency (RF) application are noted followed by outcomes and complications of RF ablation for various arrhythmias. Indications for ablation are then discussed. It is important to realize that these indications as presented are not necessarily “written in stone” and do not take the place of a “Policy Statement.” Rather, as mentioned above, this represents a general sense of agreement within the community of pediatric and adult electrophysiologists . The second half of the conference then dealt with the “nuts and bolts” of performing these proNASPE POSITION STATEMENT