Opportunities and challenges in heart rhythm research: Rationale and development of an electrophysiology collaboratory

There are many challenges in the current landscape of electrophysiology (EP) clinical and translational research, including increasing costs and complexity, competing demands, regulatory requirements, and challenges with study implementation. This review seeks to broadly discuss the state of EP research, including challenges and opportunities. Included here are results from a Heart Rhythm Society (HRS) Research Committee member survey detailing HRS members’ perspectives regarding both barriers to clinical and translational research and opportunities to address these challenges. We also provide stakeholder perspectives on barriers and opportunities for future EP research, including input from representatives of the U.S. Food and Drug Administration, industry, and research funding institutions that participated in a Research Collaboratory Summit convened by HRS. This review further summarizes the experiences of the heart failure and heart valve communities and how they have approached similar challenges in their own fields. We then explore potential solutions, including various models of research ecosystems designed to identify research challenges and to coordinate ways to address them in a collaborative fashion in order to optimize innovation, increase efficiency of evidence generation, and advance the development of new therapeutic products. The objectives of the proposed collaborative cardiac EP research community are to encourage and support scientific discourse, research efficiency, and evidence generation by exploring collaborative and equitable solutions in which stakeholders within the EP community can interact to address knowledge gaps, innovate, and advance new therapies.     

Supraventricular arrhythmias: an electrophysiology primer

Supraventricular arrhythmias are the most wide-spread group of arrhythmias and affect all age groups. Atrial fibrillation is the most common arrhythmic disorder and is even more prevalent among the elderly. Due to their prevalence, it is imperative for the clinician to be informed about these arrhythmias and treatment considerations. This paper presents a basic review of the incidence, pathophysiology, diagnosis, and treatment of supraventricular arrhythmias, along with gender differences, and discusses important implications for the health care provider. A summary of common electrocardiogram findings in supraventricular arrhythmias is presented along with a brief overview of pharmacologic agents.     

Cardiac electrophysiology: A cost-effective approach

Clinical cardiac electrophysiology is a relatively new discipline, heavily dependent upon new technology that is often expensive. In cardiac pacing, no effective alternative to permanent pacing usually exists for patients with Class I indications, so cost-reduction strategies involve appropriate selection and utilization of hardware and facilities. Cost-effective utilization of radiofrequency ablation and implantable cardioverter-defibrillators requires that these techniques be compared with alternative therapies, usually antiarrhythmic drugs. Both ablation and defibrillator implantation can be shown to be cost effective in selected populations, but a cost-conscious approach to procedures and patient selection can make them cost effective in a broad range of patients.     

Pediatric electrophysiology

Our understanding of pediatric arrhythmias continues to evolve through natural history studies of paroxysmal supraventricular tachycardia, the congenital long QT syndrome, and postoperative atrial and ventricular tachyarrhythmias. The influence of the autonomic nervous system on cardiovascular function may play a role in the sudden infant death syndrome, pallid breath-holding spells, and neurally mediated syncope; much work is necessary to understand these entities better. Therapeutic approaches to pediatric arrhythmias are extending beyond newer antiarrhythmic drugs and now include ablative therapy for many supraventricular tachyarrhythmias, both surgical and transcatheter. Advances in pacemaker therapy include novel implantation sites, down-sizing of devices, and the application of antitachycardia and rate-adaptive technologies.     

Pediatric cardiac electrophysiology

Over the past year, many advances have been made in the management of cardiac arrhythmias in the pediatric patient. It has become evident that the new surgical procedures for congenital cardiac disease can result in arrhythmia-associated morbidity and mortality. New pharmacologic agents such as adenosine have been shown to be efficacious in treating supraventricular tachycardias, and other agents such as flecainide, beta-blockers, and amiodarone are also of significant value in young patients with acute and chronic arrhythmias. Along with advances in the use of pharmacologic agents, pacing catheter techniques for the diagnosis and treatment of cardiac arrhythmias have also significantly progressed. Transcatheter ablation is safe and effective in our patient population, and an understanding of various pacemaker modalities and the physiologic parameters for optimum use have been defined. This review outlines the advances in all modes of treatment of cardiac arrhythmias.     

Superior vena cava flutter: electrophysiology and ablation

INTRODUCTION: Reentry within a major thoracic vein has been suggested as a cause of atrial arrhythmias. However, little is known about these potential reentrant circuits. METHODS AND RESULTS: Atypical atrial flutter was induced and mapped in 67 out of 225 atrial flutter ablation procedures. Reentry around the superior vena cava (SVC) was suspected in three patients. The suspected SVC flutter was induced and terminated by pacing in all patients. Fusion was demonstrated during flutter entrainment by subeustachian isthmus pacing in all of them. The postpacing interval following entrainment by pacing from different sites of the right atrium (RA) or coronary sinus was longer than the flutter cycle length. Macroreentry within the SVC was demonstrated both by sequential activation and a postpacing interval matching the flutter cycle length when pacing from different sites around the SVC in all patients. Atrial-venous-atrial electrogram sequence was demonstrated following flutter entrainment by atrial pacing. Flutter was terminated by an electrical stimulus delivered to the SVC, which was not propagated to the trabeculated RA, in one patient, and linear radiofrequency application from the distal SVC to the posterior wall of the RA, or to the superoseptal portion of the crista terminalis, in the other two. CONCLUSION: Macroreentry within the SVC is a distinctive mechanism responsible for rapid atrial activation, which is different from other reported flutter mechanisms, such as upper loop reentry. SVC longitudinal radiofrequency application can eliminate the arrhythmia without the need for complete electrical disconnection of the vein.     

Fulminant hepatic failure: a Portuguese experience

BACKGROUND: Fulminant hepatic failure (FHF) is a rare condition. Several series have been reported either by individual centres or in multicentre studies but, to our knowledge, this is the first report from a Portuguese population and might be a good example of FHF cases in a SouthWestern European population. AIMS: To present the experience in FHF of a Portuguese Hepatogastroenterological Intensive Care Unit. MATERIALS AND METHODS: Retrospective study of 61 cases of FHF consecutively admitted between February 1992 and October 2006. Definition and classification of FHF were those suggested by Trey and Davidson (1970) and O'Grady et al. (1993), respectively. Criteria and contraindications for hepatic transplantation (HT) were those proposed by Bernuau et al. (1991) and Mu?oz (1993), respectively. RESULTS: Fifty-seven per cent of patients were women and median age was 37 years (range: 8-73). Most common cause of FHF was indeterminate (26%) followed by viral (23%) and drug-induced (23%), with 51% of cases with a hyperacute evolution. Global HT rate was 54% with criteria for HT present in 87% of the patients resulting in an applicability rate of 62%. Overall survival was 69% and transplant-free survival was 15%; transplanted patients had survival rates of 70 and 68% at 6 and 12 months, respectively. CONCLUSIONS: Drug-induced and viral agents were responsible for almost half of FHF cases with a clear predominance of hyperacute presentation. The HT rate was 54% and the applicability rate was 62%. The overall 1 year survival of 69% might reflect the adequacy of the HT criteria used.     

Intracardiac echocardiography in electrophysiology

Intracardiac echocardiography (ICE) broadens the spectrum of echocardiographic techniques. Modern 10F sector echocardiographic catheters introduced into the right atrium allow high quality imaging of all cardiac structures, including pulse and continuous wave Doppler and/or color Doppler. The main indication for ICE appears to be monitoring of catheter ablation of complex arrhythmic substrates such atrial fibrillation, postincisional tachycardias and ventricular tachycardias. The other important role of ICE is the early diagnosis and prevention of complications during ablation procedures. These include those occurring during transseptal catheterization, damage to cardiac structures, left atrial thrombus formation, pulmonary venous stenosis, esophageal injury and pericardial effusion.