Atrial fibrillation ablation strategies and technologies: past, present, and future.

Catheter ablation is an established treatment option for atrial fibrillation (AF), and pulmonary vein isolation (PVI) has become the gold standard in AF ablation. AF recurrence after PVI remains an important clinical problem. Recovery of conduction from the pulmonary veins (PVs) is considered the dominant mechanism for AF recurrence in paroxysmal AF. However, the underlying mechanism of AF recurrence after PVI is more complex in patients with persistent and longstanding persistent AF. Different ablation technologies and energy sources have been developed aimed at improving lesion quality and durability with an acceptable safety profile. Novel technologies are under evaluation which have a great potential to produce permanent PVI after a single ablation procedure. However, clinical value of these novel devices needs to be tested in adequately powered randomized controlled trials. In this article, we review the history of catheter ablation for AF and discuss the present and future ablation technologies.

Energy Sources for the Surgical Treatment of Atrial Fibrillation.

The surgical treatment of atrial fibrillation has evolved over the past 2 decades due to the advent of ablation technology, and the introduction of less invasive surgical approaches. Current devices produce ablation lines that aim to replace the incisions of traditional surgical ablation strategies, such as the Cox-Maze procedure. This has helped to simplify and shorten surgical ablation procedures and has allowed for the development of minimally invasive surgical techniques. This review discusses surgical ablation energy sources and devices, providing background on device characteristics, mechanism of tissue injury, and success in creating transmural lesions.

The Pioneering and Unknown Stereotactic Approach of Roeder and Orthner from Göttingen. Part I. Surgical Technique for Tailoring Individualized Stereotactic Lesions.

During the 1950s through the 1970s, Hans Orthner and Fritz Roeder, two German neurologists from Göttingen, developed a sophisticated technique to perform functional stereotactic surgery with outstanding accuracy. They introduced direct air ventriculography performed in the same surgical session as the ablative stereotactic procedure. For individualized surgical targeting, Orthner prepared a stereotactic atlas (>60 brains) with an ingenious brain-slicing device, the Göttinger macrotome. Brains were grouped based on similarity of six different head and ventricle measurements. A brain cluster representing the best match for a patient was selected for stereotactic targeting. Stereotactic lesions were tailored in an individual manner and shaped by stringing together multiple small coagulations following intraoperative test stimulation. This was achieved from a single probe trajectory by using well-engineered string electrodes with calibrated curving and involved laborious calculations. Only high-frequency thermocoagulation was regarded as appropriate for lesioning. With this meticulous technique, the most advanced stereotactic procedures were performed, including bilateral pallidotomy that ultimately could be restricted to the ansa lenticularis and ventromedial hypothalamotomy, the most delicate stereotactic operation performed to date. Outside Göttingen, this technique has only been used by Prof. Dieter Müller in Hamburg, Germany. This elaborate stereotactic approach is widely unknown and deserves to be discussed in a historical context.

History of Cardiothoracic Surgery at Washington University in Saint Louis.

The Division of Cardiothoracic Surgery at Washington University evolved a century ago to address what many considered to be the last surgical frontier, diseases of the chest. In addition, as one of the first training programs in thoracic surgery, Washington University has been responsible for educating more thoracic surgeons than nearly any other program in the world. Beginning with Evarts A. Graham and continuing through to Ralph J. Damiano Jr., the leaders of the division have had a profound impact on the field of cardiothoracic surgery.

The management and prognosis of patients with hepatocellular carcinoma: what has changed in 20 years?

BACKGROUND & AIMS: There has been remarkable progress in the management of hepatocellular carcinoma (HCC) during the last several decades, but its effect on the prognosis of HCC patient needs clarification. We analysed the changes that affected prognosis of HCC patients diagnosed over two different eras. METHODS: A retrospective study of 1318 patients diagnosed with HCC from 1986 to 2012 was conducted. Analysis was done according to two cohorts, cohort 1 (patients diagnosed with HCC from 1986 to 1992) and cohort 2 (patients diagnosed from 2006 to 2012). RESULTS: Hepatitis B virus was the most common cause of liver disease for both cohorts (66.2% and 66.0%). The proportion of patients with Barcelona Clinic Liver Cancer stage 0/A was significantly lower in cohort 1 than in cohort 2 (14.4% vs. 39.5%, P < 0.001). The proportions of patients diagnosed during surveillance and general health check-up were significantly higher in cohort 2 than in cohort 1 (28.6% vs. 10.6% and 26.3% vs. 7.9%, respectively) while those diagnosed during symptomatic evaluation was significantly higher in cohort 1 than in cohort 2 (45.1 vs. 81.4%, P < 0.001). Surgical resection rate was similar between the two cohorts (26.1% vs 26%) while the transcatheter arterial chemoembolization rate which was the highest in cohort 1 (40.6%) was overtaken by radiofrequency ablation in cohort 2 (55%) at BCLC stage 0/A. Median survival duration in cohort 2 was significantly longer than cohort 1 (65.0 vs. 7.9 months, P < 0.001). CONCLUSIONS: Implementation of national cancer surveillance and the advancement of treatment modalities have likely led to early detection of HCC and improvements in prognosis over the last 20 years.

Dos décadas de seguimiento exitoso de la primera ablación de arritmias por catéter de radiofrecuencia realizado en la historia de la medicina del Paraguay / Two decades of succesful follow-up of the first radiofrequency catheter arrhythmia ablation done in the history of medicine in Paraguay

La técnica de mapeo endocárdico durante el estudio electrofisiológico ha sido extensamente empleada en el análisis de las taquicardias paroxísticas supraventriculares (TPS). Mediante este mapeo endocárdico y el análisis meticuloso de los electrogramas endocárdicos y los respectivos intervalos de conducción, es posible localizar el sitio de origen de las arritmias y así facilitar su tratamiento ablativo por medio de catéteres de radiofrecuencia. Se describe el caso de un hombre de 29 años con síndrome de Wolff-Parkinson-White (WPW) que manifiestó que presentaba varios episodios documentados de TPS con serio compromiso hemodinámico que motivaba su frecuente internación en terapia intensiva. El mapeo electrofisiológico endocárdico meticuloso demostró la presencia de un haz anómalo de Kent auriculoventricular izquierdo en posición posteroseptal. El período refractario absoluto del haz anómalo de Kent fue de 240 ms. La primera emisión de radiofrecuencia a través de un catéter adecuadamente posicionado previo terminó la taquicardia. La taquicardia permaneció no inducible a partir de entonces. En estas dos décadas de seguimiento clínico, el paciente no ha presentado ni un solo episodio de taquicardia. La curación definitiva generada por la ablación del haz anómalo de Kent ha proporcionado un cambio drástico, total y beneficioso en la calidad de vida al paciente. Los beneficios clínicos y socioeconómicos son mayores cuanto más temprano en la evolución se realice el procedimiento de ablación de arritmias.

Endocardial mapping has been widely used for the analysis of supraventriculartachycardias during electrophysiological study. This mapping and the detailed analysis ofendocardial electrograms and conduction intervals allow for the localization of the site oforigin of the arrhythmias thus facilitating curative treatment with radiofrequency catheterablation. The case describes our 29 years old patient with manifested Wolff-ParkinsonWhitesyndrome that presented frequent, documented episodes of paroxysmal supraventricular tachycardia with serious hemodynamic alteration that needed frequentadmissions to intensive care units despite the use of 2-3 antiarrhythmic agents per day. Adetailed endocardial mapping showed a left posteroseptal accessory pathway. Theaccessory pathway effective refractory period is 240 ms. The first radiofrequency emissionthrough an adequately positioned radiofrequency catheter terminated the tachycardia. Thetachycardia was rendered non-inducible thereafter. In two decades of follow-up, the patienthas not presented a single episode of tachycardia. The definite cure provided by theradiofrequency ablation produced a total, dramatic, and beneficial change in the quality oflife of the patient. The clinical and socio-economical benefits are greater the earlier thearrhythmia ablation procedure is performed.

Renal Denervation: Past, Present, and Future.

Hypertension remains a leading cause of cardiovascular morbidity and mortality worldwide. It is estimated that 12.8% of hypertensive adults have resistant hypertension. The sympathetic nervous system is a well-known contributor to the pathophysiology of resistant hypertension. Renal denervation has emerged as an effective procedure to treat resistant hypertension by blocking the sympathetic nervous system. The medical device industry has developed various catheters in an effort to achieve better denervation in the absence of available testing to document adequate denervation. By adding a sham control group to the study design, researchers found that the results of the Renal Denervation in Patients With Uncontrolled Hypertension study (SYMPLICITY HTN-3) showed that renal denervation was not superior to placebo in decreasing systolic blood pressure. Although SYMPLICITY HTN-3 successfully addressed many issues that might have biased the previously published data, incomplete denervation caused by limited operator experience, catheter design, and the radiofrequency ablation technology may have accounted for the discrepancy of the results. This, along with differences in the study design and population, should direct future renal denervation studies. This article reviews the available literature and proposes future directions for renal denervation studies. It also provides a detailed comparison of the available catheters and their respective clinical data.

Renal denervation in the treatment of drug-resistant hypertension: current knowledge and future perspectives.

Resistant hypertension remains a challenging issue even for modern medicine. Therefore, research is focusing on the development of new technologies to optimize the treatment of this condition. It has been demonstrated that the dysfunction of the sympathetic nervous system is crucial in the development and maintenance of advanced stages of hypertension. Based on these findings, clinical trials have recently shown that catheter-based percutaneous renal denervation therapy is safe and effective in the treatment of resistant hypertension. This review discusses the current scientific knowledge of renal denervation therapy in resistant hypertension, including the different methods that have been described in the literature so far, as well as limitations of the available data. Furthermore, new potential targets for this fascinating therapy will be addressed.

History, ethics, advantages and limitations of experimental models for hepatic ablation.

Numerous techniques developed in medicine require careful evaluation to determine their indications, limitations and potential side effects prior to their clinical use. At present this generally involves the use of animal models which is undesirable from an ethical standpoint, requires complex and time-consuming authorization, and is very expensive. This process is exemplified in the development of hepatic ablation techniques, starting experiments on explanted livers and progressing to safety and efficacy studies in living animals prior to clinical studies. The two main approaches used are ex vivo isolated non-perfused liver models and in vivo animal models. Ex vivo non perfused models are less expensive, easier to obtain but not suitable to study the heat sink effect or experiments requiring several hours. In vivo animal models closely resemble clinical subjects but often are expensive and have small sample sizes due to ethical guidelines. Isolated perfused ex vivo liver models have been used to study drug toxicity, liver failure, organ transplantation and hepatic ablation and combine advantages of both previous models.

[Atrial fibrillation ablation in the real world: the less we know, the more we ablate?]. / Ablación de la fibrilación auricular en la vida real: cuanto menos sabemos, más quemamos?

Catheter ablation is now well established as an alternative or complementary therapeutic approach to the use of anti-arrhythmic drugs in selected patients with atrial fibrillation. Although pulmonary vein isolation is very effective in patients with paroxysmal atrial fibrillation, it is still not possible to identify the arrhythmogenic substrate responsible for fibrillation in a large number of patients, principally those with persistent atrial fibrillation. As a result, anatomic areas in the atrium that are not involved in either the initiation or maintenance of atrial fibrillation may undergo ablation. Until we have a better understanding of the pathophysiology of the different stages of atrial fibrillation, it would be wise to treat arrhythmias early, before anatomic or electrical deterioration of the atrium occurs.

Surgical ablation for atrial fibrillation.

This paper reviews the history of surgical procedures developed for eradication of atrial fibrillation (AF) during cardiac surgery for structural heart disease, and in patients with AF without other indication for cardiac surgery. Current evidence indicates that, despite their proven efficacy, the Cox-Maze procedure and its modifications require cardiopulmonary bypass and cannot be easily justified in the case of AF without other indication for cardiac surgery. In patients undergoing cardiac surgery for mitral valve disease, concomitant ablation techniques using modifications of the Maze and alternative energy sources appear to be safe and effective in treating AF, especially in non-rheumatic disease. Minimally invasive epicardial ablation has been recently developed and can be performed on a beating heart through small access incision ports. Various techniques combining pulmonary vein isolation, ganglionated plexi ablation, and left atrial lines have been tried. Initial results are promising but further clinical experience is required to establish ideal lesion sets, appropriate energy sources, and the benefit-risk ratio of such an approach in patients without other indication for cardiac surgery. The role of surgical ablation in the current management of AF is under investigation.