Pericardial anatomy for the interventional electrophysiologist

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society (HRS), the Asia Pacific HRS, and the Latin American HRS.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society .

Epicardial Ventricular Tachycardia Ablation: Patient Selection, Access, and Ablation Techniques and Strategies to Manage Complications

Epicardial ventricular tachycardia ablation is an important treatment modality for refractory ventricular tachycardia. This comprehensive review guides clinicians through optimized strategies for improved procedural outcomes and patient safety during epicardial ventricular tachycardia ablation. Patient selection criteria, including cardiomyopathy type, electrocardiogram findings, and prior ablation history, are discussed. Detailed techniques for safe pericardial access are provided. Potential complications and strategies for prevention and management are explored. The review also addresses challenges and pitfalls of epicardial mapping and ablation.

Evaluating chest pain in patients with post COVID conditions permission to think outside of the box

Chest pain is among the most common symptoms of post-COVID-19 Conditions (PCC) that prompts medical attention. Because the SARS-CoV-2 virus has proclivity for many organs and organ systems in the chest, ranging from the heart, lungs, great vessels, lymphatics, and peripheral nerves, clinicians evaluating patients with chest pain must consider a broad differential diagnosis and take a comprehensive approach to management.

Living Anatomy of the Pericardial Space: A Guide for Imaging and Interventions

The pericardium of the human heart has received increased attention in recent times due to interest in the epicardial approach for cardiac interventions to treat cardiac arrhythmias refractory to conventional endocardial approaches. To support further clinical application of this technique, it is fundamental to appreciate the living anatomy of the pericardial space, as well as its relationships to the surrounding structures. The anatomy of the pericardial space, however, is extremely difficult regions to visualize. This is due to its complex 3-dimensionality, and the "potential" nature of the space, which becomes obvious only when there is collection of pericardial fluid. This potential space, which is bounded by the epicardium and pericardium, can now be visualized by special techniques as we now report, permitting appreciation of its living morphology. Current sources of knowledge are limited to the dissection images, surgical images, and/or illustrations, which are not necessarily precise or sufficient to provide relevant comprehensive anatomical knowledge to those undertaking the epicardial approach. The authors demonstrate, for the first time to their knowledge, the 3-dimensional living anatomy of the pericardial space relative to its surrounding structures. They also provide correlative anatomy of the left sternocostal triangle as a common site for subxiphoid access. The authors anticipate their report serving as a tool for education of imaging and interventional specialists.

Access routes, devices and guidance methods for intrapericardial delivery in cardiac conditions

Drug deposition into the intrapericardial space is favourable for achieving localised effects and targeted cardiac delivery owing to its proximity to the myocardium as well as facilitating optimised pharmacokinetic profiles and a reduction in systemic side effects. Access to the pericardium requires invasive procedures but the risks associated with this have been reduced with technological advances, such as combining transatrial and subxiphoid access with different guidance methods. A variety of introducer devices, ranging from needles to loop-catheters, have also been developed and validated in pre-clinical studies investigating intrapericardial delivery of therapeutic agents. Access techniques are generally well-tolerated, self-limiting and safe, although some rare complications associated with certain approaches have been reported. This review covers these access techniques and how they have been applied to the delivery of drugs, cells, and biologicals, demonstrating the potential of intrapericardial delivery for treatments in cardiac arrhythmia, vascular damage, and myocardial infarction.

Combined epicardial and endocardial ablation for atrial fibrillation: Best practices and guide to hybrid convergent procedures

The absence of strategies to consistently and effectively address nonparoxysmal atrial fibrillation by nonpharmacological interventions has represented a long-standing treatment gap. A combined epicardial/endocardial ablation strategy, the hybrid Convergent procedure, was developed in response to this clinical need. A subxiphoid incision is used to access the pericardial space facilitating an epicardial ablation directed at isolation of the posterior wall of the left atrium. This is followed by an endocardial ablation to complete isolation of the pulmonary veins and for additional ablation as needed. Experience gained with the hybrid Convergent procedure during the last decade has led to the development and adoption of strategies to optimize the technique and mitigate risks. Additionally, a surgical and electrophysiology "team" approach including comprehensive training is believed critical to successfully develop the hybrid Convergent program. A recently completed randomized clinical trial indicated that this ablation strategy is superior to an endocardial-only approach for patients with persistent atrial fibrillation. In this review, we propose and describe best practice guidelines for hybrid Convergent ablation on the basis of a combination of published data, author consensus, and expert opinion. A summary of clinical outcomes, emerging evidence, and future perspectives is also given.

Ganglionated Plexi Ablation for the Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is the most common type of cardiac arrhythmia and is associated with significant morbidity and mortality. The autonomic nervous system (ANS) plays an important role in the initiation and development of AF, causing alterations in atrial structure and electrophysiological defects. The intrinsic ANS of the heart consists of multiple ganglionated plexi (GP), commonly nestled in epicardial fat pads. These GPs contain both parasympathetic and sympathetic afferent and efferent neuronal circuits that control the electrophysiological properties of the myocardium. Pulmonary vein isolation and other cardiac catheter ablation targets including GP ablation can disrupt the fibers connecting GPs or directly damage the GPs, mediating the benefits of the ablation procedure. Ablation of GPs has been evaluated over the past decade as an adjunctive procedure for the treatment of patients suffering from AF. The success rate of GP ablation is strongly associated with specific ablation sites, surgical techniques, localization techniques, method of access and the incorporation of additional interventions. In this review, we present the current data on the clinical utility of GP ablation and its significance in AF elimination and the restoration of normal sinus rhythm in humans.

Anatomy of the Pericardial Space

The pericardial cavity and its boundaries are formed by the reflections of the visceral and parietal pericardial layers. This space is an integral access point for epicardial interventions. As the pericardial layers reflect over the great vessels and the heart, they form sinuses and recesses, which restrict catheter movement. The epicardial vasculature is also important when performing nearby catheter ablation. The phrenic nerve and esophagus are other important structures to appreciate so as to avoid collateral injury. In addition, the Larrey space, or left sternocostal triangle, is a key avascular window through which pericardial access can be safely achieved.

Percutaneous Epicardial Approach to Catheter Ablation of Cardiac Arrhythmias

Since their introduction >2 decades ago, percutaneous catheter-based epicardial mapping and ablation have become widely adopted by cardiac electrophysiologists around the world. Although epicardial mapping has been used for catheter ablation of a wide variety of cardiac arrhythmias, its most common use is for ablation of intramural and subepicardial substrates that give rise to ventricular tachycardia, particularly in patients with nonischemic cardiomyopathy. As such, the subxiphoid percutaneous epicardial approach has emerged as an important adjunct, and, in some cases, is the preferred strategy in this regard. This review discusses the rationale and indications for epicardial catheter mapping and/or ablation. This paper also reviews the prevalence of epicardial arrhythmias and their electrocardiographic criteria. In addition, it examines the anatomy of the pericardium and commonly used epicardial access techniques, as well as the optimal methodologies for epicardial mapping and ablation and the impact of epicardial fat. Finally, this review discusses the potential of the various complications associated with the percutaneous epicardial approach, in addition to patient-specific risk factors, and potential strategies to mitigate the risk of complications.

Interplay between cardiac function and heart development

Mechanotransduction refers to the conversion of mechanical forces into biochemical or electrical signals that initiate structural and functional remodeling in cells and tissues. The heart is a kinetic organ whose form changes considerably during development and disease. This requires cardiomyocytes to be mechanically durable and able to mount coordinated responses to a variety of environmental signals on different time scales, including cardiac pressure loading and electrical and hemodynamic forces. During physiological growth, myocytes, endocardial and epicardial cells have to adaptively remodel to these mechanical forces. Here we review some of the recent advances in the understanding of how mechanical forces influence cardiac development, with a focus on fluid flow forces. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

Arrhythmias in chagasic cardiomyopathy

Chagas disease, a chronic parasitosis caused by the protozoa Trypanosoma cruzi, is an increasing worldwide problem because of the number of cases in endemic areas and the migration of infected individuals to more developed regions. Chagas disease affects the heart through cardiac parasympathetic neuronal depopulation, immune-mediated myocardial injury, parasite persistence in cardiac tissue with secondary antigenic stimulation, and coronary microvascular abnormalities causing myocardial ischemia. A lack of knowledge exists for risk stratification, management, and prevention of ventricular arrhythmias in patients with chagasic cardiomyopathy. Catheter ablation can be effective for the management of recurrent ventricular tachycardia.

Physiology of pericardial fluid production and drainage

The pericardium is one of the serosal cavities of the mammals. It consists of two anatomical structures closely connected, an external sac of fibrous connective tissue, that is called fibrous pericardium and an internal that is called serous pericardium coating the internal surface of the fibrous pericardium (parietal layer) and the heart (visceral layer) forming the pericardial space. Between these two layers a small amount of fluid exists that is called pericardial fluid. The pericardial fluid is a product of ultrafiltration and is considered to be drained by lymphatic capillary bed mainly. Under normal conditions it provides lubrication during heart beating while the mesothelial cells that line the membrane may also have a role in the absorption of the pericardial fluid along with the pericardial lymphatics. Here, we provide a review of the the current literature regarding the physiology of the pericardial space and the regulation of pericardial fluid turnover and highlight the areas that need to be further investigated.

Percutaneous epicardial ablation in ventricular arrhythmias

INTRODUCTION

Reentrant circuits of ventricular tachycardia may involve not only the endocardium but also the epicardium. Epicardial ablation can be useful in these situations.

OBJECTIVE

The aim of this study was to assess efficacy, safety and complications in a series of consecutive patients who underwent ablation of ventricular tachycardia with epicardial mapping.

METHODS

The study included all patients undergoing ventricular tachycardia ablation with epicardial mapping from 2004 to 2012. Of a total of 95 ablations, an epicardial approach was attempted in nine patients, eight male, mean age 58±12 years. Endocardial mapping was performed in all patients previously or simultaneously. The etiology of the arrhythmia was non-ischemic in eight patients and ischemic in one. We compared the number of events in the six months prior to the epicardial procedure and six months after.

RESULTS

Percutaneous epicardial access was achieved in eight patients. In one case it was not possible due to the presence of adhesions. In none of the patients was the procedure repeated and there were no major complications during hospitalization. In a mean follow-up of 3.5±1.2 years, one patient suffered stroke; there were no other medium-to-long-term complications and the number of ventricular tachycardia episodes was reduced in all patients after ablation.

CONCLUSIONS

Epicardial radiofrequency ablation of ventricular tachycardia was effective in reducing morbidity in eight patients, with a low risk of complications in the short and medium-to-long term.

Learning from the pulmonary veins

The purpose of this article is to review the basic embryology and anatomy of the pulmonary veins and the various imaging techniques used to evaluate the pulmonary veins, as well as the radiologic findings in diseases affecting these structures. Specific cases highlight the clinical importance of the imaging features, particularly the findings obtained with multidetector computed tomography (CT). Pulmonary vein disease can be broadly classified into congenital or acquired conditions. Congenital disease, which often goes unnoticed until patients are adults, mainly includes (a) anomalies in the number or diameter of the vessels and (b) abnormal drainage or connection with the pulmonary arterial tree. Acquired disease can be grouped into (a) stenosis and obstruction, (b) hypertension, (c) thrombosis, (d) calcifications, and (e) collateral circulation. Pulmonary vein stenosis or obstruction, which often has important clinical repercussions, is frequently a result of radiofrequency ablation complications, neoplastic infiltration, or fibrosing mediastinitis. The most common cause of pulmonary venous hypertension is chronic left ventricular failure. This condition is difficult to differentiate from veno-occlusive pulmonary disease, which requires a completely different treatment. Pulmonary vein thrombosis is a rare, potentially severe condition that can have a local or distant cause. Calcifications have been described in rheumatic mitral valve disease and chronic renal failure. Finally, the pulmonary veins can act as conduits for collateral circulation in cases of obstruction of the superior vena cava. Multidetector CT is an excellent modality for imaging evaluation of the pulmonary veins, even when the examination is not specifically tailored for their assessment.

Anatomic variants mimicking pathology on echocardiography: differential diagnosis

Differentiation of normal from abnormal findings is critical in echocardiography. Anatomic variants occurring in normal cardiac developments often simulate pathologic entities. This review focuses on the differential diagnosis of normal anatomic structures from pathologic ones in echocardiography.

The Emerging Role of Epicardial Ablation

Sosa and colleagues first described a percutaneous approach (via the subxiphoid area) to access the pericardial space in 1996. Epicardial mapping and ablation is increasingly used for the treatment of supraventricular and ventricular arrhythmias and represents an adjunctive approach for challenging arrhythmias to improve procedural success rates. Epicardial ablation should be considered not only after the failure of an endocardial ablation but often as a first-line approach. Complications may occur during percutaneous access and epicardial ablation, and these might be reduced or avoided by improved operator skills and experience. New tools to access the epicardial space are being evaluated.

Pericardial approach for cardiac therapies: old practice with new ideas

Treatment of cardiac disease via the epicardium fell under the domain of cardiac surgery due to the need for an open thoracotomy. Since an open thoracotomy is invasive in nature and has the potential for complications, a minimally invasive and percutaneous approach would be more attractive for suitable patients. The recent success of epicardial ablation of refractory arrhythmia via the percutaneous pericardial approach has increased the potential for delivery of epicardial therapies. Epicardial ablation has increased the success and safety since anti-coagulation and transseptal catheterization for left atrial arrhythmias is not required. The pericardial space has also been used to deliver therapy for several cardiac diseases. There are reports on successful delivery of drugs and their efficacy. Even though there was a wide range of efficacies reported in those studies, the reported complication rates are strikingly low, which suggests that direct delivery of drugs to the epicardium via the pericardial space is safe. Furthermore, recent animal studies have supported the feasibility of epicardial delivery of biological agents, including genes, cells, and even genetically engineered tissue for therapeutic purposes. In conclusion, percutaneous pericardial cannulation of closed pericardial space can play a significant role in providing non-surgical therapy for cardiovascular diseases. However, it requires skills and operator experiences. Therefore, there is need to further develop new tools, safer techniques, and effective procedure environment before generalizing this procedure.

Future Developments in Nonsurgical Epicardial Therapies

The unique anatomic position of the pericardium in juxtaposition to central cardiac structures enables it to serve as the ideal vantage point for the delivery of novel cardiovascular therapies. Development of new tools to permit delivery of therapy in the closed pericardial space holds promise for near-surgical access to the heart, without open surgical morbidity. Early observations raise hope for the availability of epicardial leads to enhance cardiac resynchronization therapy designed for subxiphoid nonsurgical percutaneous delivery. Emerging technologies for left atrial appendage ligation may offer new strategies for preventing stroke.

Measurement and Optimization of Minimally Invasive Intervention Device Design Fitness Using a Multiobjective Weighted Isotropy Index

The recent transition from multiple-port to single-port systems in minimally invasive intervention (MII) procedures has created a need for more flexible, dexterous robotic manipulation devices capable of spanning an entire surgical workspace without the risk of collateral damage. The design of such devices requires a careful balance of the mechanical complexity needed to facilitate clinical functionality and the cost of manufacturing and operating the device. This paper presents a novel metric for measuring the design fitness of kinematically redundant robotic MII devices and for optimizing them to achieve that balance. The proposed fitness metric rewards designs that are conducive to collision avoidance and energy conservation while penalizing those with exorbitant design complexities that adversely affect the economic feasibility of an MII system. The authors’ metric is used here to design a kinematically redundant, single-port MII device capable of accessing the cardiothoracic cavity through a single subxiphoid port and reaching several regions of interest, consistent with procedures such as epicardial ablation and therapeutic substance injection, with minimal physiologic disturbance. The design of this device is determined by a morphological optimization process, which searches a discrete mechanical design parameter space, consisting of linkage parts, part dimensions, and actuator types, using genetic algorithms. The execution of specific surgical maneuvers is simulated for each candidate MII device design, and the design is improved until the fitness metric is maximized. The results of this optimization study demonstrate that redesigning a 20 degree-of-freedom (DOF) MII device using the proposed metric decreased the DOF in the design by 45% while ensuring near-optimal levels of kinematic flexibility. The results also demonstrate the ability of the fitness metric to elucidate the relationship between functionality and complexity and to produce suitable device designs over a broad range of performance and cost goals. The authors conclude that this new design fitness metric, while heuristic in nature, holds the potential to improve both the clinical value and the economy of a wide variety of single-port MII devices, including those used in cardiothoracic surgery.

Anatomy of the Pericardial Space and Mediastinum: Relevance to Epicardial Mapping and Ablation

The pericardial space is a fairly new portal for interventional cardiac electrophysiologists to access the heart and requires an understanding of its anatomic peculiarities to maneuver safely around the epicardial surfaces of the heart and great veins. Subxiphoid puncture should allow the diaphragm and fibrous pericardium to be crossed without entering the right ventricle, which is the most anteriorly situated cardiac chamber. The phrenic nerves descend on the fibrous pericardium bilaterally. The right nerve is related to the superior caval vein and the superior right pulmonary vein, whereas the left nerve takes variable courses over the left atrial appendage and the left ventricle. Related to the fibrous pericardium overlying the posterior wall of the left atrium is the esophagus.

Epicardial Catheter Ablation of Atrial Fibrillation

Atrial fibrillation (AF) can cause significant symptoms despite control of ventricular rate, and for some patients a rhythm-control strategy is more appropriate. Because antiarrhythmic drugs have limited efficacy for treating AF and can cause significant side effects, nonpharmacologic therapy has found a growing role in the treatment of this arrhythmia. While endocardial catheter ablation has shown superior results over drug therapy, long-term clinical outcomes are still disappointing, especially for persistent AF. This article discusses percutaneous epicardial catheter ablation, the rationale for using this approach to treat AF, anatomy relevant to the approach, challenges in performing such procedures, and finally, the potential future directions in this promising new field.

The Pericardial Space: Obtaining Access and an Approach to Fluoroscopic Anatomy

The pericardial space is now increasingly used as a means and vantage point for mapping and ablating various arrhythmias. In this review, present techniques to access the pericardial space are examined and potential improvements over this technique discussed. The authors then examine in detail the regional anatomy of the pericardial space relevant to the major arrhythmias treated in contemporary electrophysiology. In each of these sections, emphasis is placed on anatomic fluoroscopic correlation and avoiding complications that may result.

How to Learn Epicardial Intervention Techniques in Electrophysiology

This article outlines an approach to begin an epicardial ablation program in the electrophysiology laboratory. There are some logistical hurdles in getting this program up and running, so this is a good opportunity to review the indications, the risks that are inherent in the procedure, and the infrastructure necessary in the electrophysiology laboratory and institution to perform the procedure safely and effectively.

Evaluation of catheter ablation of periatrial ganglionic plexi in patients with atrial fibrillation

Recent data suggests that the cardiac autonomic nervous system has an important role in the initiation and maintenance of atrial fibrillation (AF). This study investigated (1) the feasibility of identifying and targeting these autonomic ganglia using endocardial radiofrequency stimulation and ablation, respectively; (2) the efficacy of endocardial ablation to completely eliminate the vagal response elicited from epicardial stimulation; and (3) the effect of autonomic ablation on the acute inducibility of AF. The study included 18 patients referred for catheter ablation of suspected vagal-mediated AF. The endocardial left atrial surface was stimulated at high frequency (20 to 50 Hz) to elicit a vagal response. In selected patients (n = 5), pericardial access was obtained using a subxyphoid puncture to permit epicardial stimulation. Catheter ablation of the putative autonomic ganglionic sites was performed from the left atrial endocardium using irrigated radiofrequency energy. After ablation of all identifiable autonomic ganglia, high-frequency pacing was repeated to induce AF. In all patients, stimulation at certain endocardial sites elicited a vagal response. Endocardial ablation abrogated this vagal responsiveness. Furthermore, for sites accessible from the pericardium, the vagal response elicited using epicardial stimulation was also eliminated. Despite successful ablation of these ganglia, AF was still inducible in 17 of 18 patients. In conclusion, successful ablation of autonomic ganglia from an endocardial approach can be reliably achieved using an irrigated catheter. In addition, ablation of these structures in patients with vagal-mediated AF is insufficient to prevent its acute reinduction with high-frequency atrial stimulation.

Thinking outside the abdominal box: safe use of the epipericardial fat pad window for percutaneous radiofrequency ablation of hepatic dome tumors

Percutaneous imaging-guided tumor ablation is being increasingly performed for local disease control in a variety of primary and secondary neoplasms. Herein, the authors detail their experience with four patients in whom the epipericardial fat pad was traversed to access tumors within the hepatic dome for radiofrequency ablation. The procedure was technically successful in all patients, and the use of this novel window helped avoid crossing the pleura.

Isolating the Posterior Left Atrium and Pulmonary Veins with a "Box" Lesion Set: Use of Epicardial Ablation to Complete Electrical Isolation

Similar to the surgical mini-maze procedure, the posterior "box" lesion set employs linear ablation lesions along the anterior aspects of both sets of PVs connected by a roof line and an inferior line to electrically isolate the PVs and complete posterior LA wall en masse. However, creating fully transmural linear atrial lesions can be difficult to achieve, even with an irrigated ablation catheter. This report details a case wherein a combined endocardial and epicardial approach was required to create an electrically continuous posterior box lesion in a patient with persistent AF.

Combined ventricular endocardial and epicardial substrate mapping using a sonomicrometry-based electroanatomical mapping system

BACKGROUND

Substrate mapping using a magnetic electroanatomical mapping system (MEAM) has been shown to accurately delineate the location/extent of scarred myocardium. This study examined the ability of a sonomicrometry-based electroanatomic mapping system (SEAM) to render endocardial and epicardial substrate maps of infarcted ventricular myocardium.

METHODS AND RESULTS

In 7 swine with healed myocardial infarctions, combined epicardial and endocardial left ventricular (LV) substrate maps were created with both SEAM and MEAM mapping systems using 246+/-68 and 244+/-44 points respectively. Scarred myocardium was identified based upon bipolar electrogram amplitude < 1.5 mV, and radiofrequency ablation lesions were delivered to the scar border as defined by the sonomicrometry mapping system. The LV endocardial chamber volume as defined by SEAM (125+/-46 ml) correlated well with that defined by the MEAM (137+/-45 ml, r=0.77, p < 0.05). The area of infarcted tissue as determined by SEAM was highly correlated with that determined by gross pathology (r=0.96 for endocardial scar and r=0.92 for epicardial scar p < 0.05). The scar area calculated by the SEAM system also correlated well with the scar area determined by the MEAM system (0.91 for endocardial scar and 0.90 for epicardial scar p < 0.05). Finally, the sonomicrometry-based system was able to guide the placement of radiofrequency ablation lesions to the borders of the scar.

CONCLUSIONS

This study demonstrates that the sonomicrometry-based mapping can accurately reconstruct three-dimensional voltage maps of the endocardial and epicardial ventricular surfaces and guide the placement of ablation lesions along the scar border zone.