Important physiologic and anatomic differences exist between the epicardium and endocardium, particularly of the ventricles, and these differences affect ablation biophysics. Absence of passive convective effects conferred by circulating blood as well as the presence of epicardial fat and vessels and absence of intracavitary ridges and structures affect ablation lesion size when performing epicardial catheter-based ablation, whether using radiofrequency or cryothermal energy. Understanding differential effects in each environment is important in informing strategies to increase ablation lesion depth. When using actively cooled radiofrequency ablation, local impedance can be altered to selectively augment energy delivery.The intracoronary artery and venous routes provide unique roadmaps for mapping and interventions for ventricular arrhythmias and certain atrial arrhythmias. The unique anatomic location of these vessels on the epicardial surface enables mapping/interventions without the need to access the pericardial space. These anatomic routes also track deep into certain intramural regions, with interventions that are not accessible from either epicardial or endocardial routes. To map smaller vessels, multipolar catheters and wires are used to record local electrograms. Endocardial/epicardial ablation at adjacent sites is sometimes required to enhance successful outcomes. This article describes tools, techniques, and site-specific mapping and interventions.Hybrid surgical ventricular tachycardia (VT) ablation combines surgical epicardial access/exposure with contemporary mapping and ablation techniques adapted from percutaneous catheter ablation procedures. Patients considered for a hybrid surgical approach for VT are those who have had prior cardiac surgery or failed percutaneous epicardial access due to pericardial adhesions. They often represent the most challenging end of the spectrum of patients and usually have undergone multiple unsuccessful ablations. In this review, the indications, preprocedure work-up, ablation techniques, and outcomes from hybrid surgical access VT ablations are discussed as well as key technical details that present unique challenges to its success.The observations afforded by epicardial mapping have not only increased the appreciation of distinct epicardial structures in the left atrium but also underscore the need to address the substrate transmurally. Although epicardial access and ablation have attendant risks, comparative studies with hybrid surgical approaches are lacking. In the search to find unifying mechanisms of atrial fibrillation, a conceptual shift that emphasizes the substrate in 3 dimensions, with the epicardium distinct from the endocardium, holds promise for future investigation and evolving therapeutic tools.Supraventricular arrhythmias are the most common cardiac arrhythmias encountered; however, it is uncommon that supraventricular tachycardias require percutaneous epicardial access for successful mapping and ablation. There are particular scenarios where epicardial access and ablation should be considered. Certain accessory pathways particularly in the posteroseptal region may require epicardial access for successful ablation. These pathways may also be approached from within the coronary sinus system. In addition, tachycardias near the phrenic nerve in the right atrium or left atrium may require epicardial access for successful ablation or to allow displacement of the phrenic nerve facilitating safe catheter ablation.Brugada syndrome is an inherited cardiac condition characterized by a typical electrocardiogram signature of coved-type ST-segment elevation in the right precordial leads and ventricular arrhythmias leading to sudden cardiac death, in the absence of unequivocal structural heart disease. Brugada syndrome specifically affects the right ventricle, which predisposes to cardiac arrest. Besides medical management with quinidine, emerging data indicate that catheter ablation can help reduce the ventricular arrhythmia burden in these patients. This review explores the mechanisms of ventricular arrhythmia, current approaches and evidence for ablating the epicardial arrhythmogenic substrate in this condition.Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease characterized by progressive fibrofatty replacement of the myocardium, right ventricular enlargement, and malignant ventricular arrhythmias. Ventricular tachycardia (VT) may be seen in all stages of the disease and is associated with sudden cardiac death. In patients who failed anti-arrhythmic medical therapy, catheter ablation has become an attractive therapeutic option to reduce VT burden and implantable cardioverter-defibrillator interventions. In this article, the authors aim to address the overall concepts of epicardial catheter ablation in ARVC, focusing on substrate characterization and ablation strategies.In patients with nonischemic cardiomyopathy, epicardial ablation is critical in targeting epicardial paravalvular substrate. Epicardial access and ablation can be performed safely with attention to epicardial structures, such as the coronary arteries, phrenic nerve, and epicardial fat. This review explores the indications, techniques, complications, and outcomes of epicardial ablation in patients with nonischemic cardiomyopathy. Although epicardial ablation adds to the complexity and risk of the ablation procedure, it is a vital tool that, combined with endocardial mapping and ablation, improves outcomes in patients with nonischemic cardiomyopathy suffering from ventricular arrhythmias.Catheter ablation can effectively reduce the frequency of ventricular tachycardia in ischemic cardiomyopathy by ablating sites of reentry within complex regions of myocardial scar. In cases of near transmural infarction, this arrhythmia substrate may be nearer the epicardium than the endocardium, and epicardial ablation may be necessary. An epicardial substrate location can potentially be predicted by imaging that suggests transmural infarction. Percutaneous epicardial ablation improves outcomes in selected patients, but is higher risk and avoided in patients with prior coronary artery bypass grafting.Ventricular arrhythmias (VAs) occurring in the absence of structural heart disease or ion channelopathies are referred to as idiopathic. They can clinically present with frequent monomorphic premature ventricular contractions, nonsustained ventricular tachycardia (VT), or sustained VT, and generally share a benign prognosis. Approximately 4% to 10% of idiopathic VAs have an epicardial site of origin, represented in most cases by the left ventricular summit and, less frequently, by the cardiac crux. Epicardial foci can be addressed by catheter ablation via the coronary venous system tributaries. In rarer instances, a direct epicardial access from a subxiphoid approach is needed.Accessing the epicardial space without a sternotomy or a surgical pericardial window to treat ventricular arrhythmias in Chagas disease became a medical necessity in South America. Since the introduction of the dry percutaneous epicardial access approach, epicardial access has been standard procedure for management of ventricular arrhythmias in ischemic and nonischemic cardiomyopathies and atrioventricular accessory pathways after failed conventional endocardial ablation. Understanding the epicardial space and neighboring structures has become an important subject of teachings in electrophysiology. The evolution of complex ablation procedures to treat atrial and ventricular arrhythmias and device interventions to prevent cardioembolic stroke requires thorough understanding of pericardial anatomy.Percutaneous epicardial access continues to have a growing role within cardiac electrophysiology. The classic approach has typically been with a Tuohy needle via a subxiphoid approach guided by fluoroscopic landmarks and tactile feedback. Recent developments have highlighted the role of the micropuncture needle, electroanatomic mapping, and real-time pressure sensors to reduce complications. Further, different access sites, such as the right atrial appendage, have been described and may offer a novel approach to percutaneous epicardial access. In addition, future directions of percutaneous access may involve direct visualization, near-field impedance monitoring, and real-time virtual imaging.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.

Mental health diagnostic approaches are seeking to identify biological markers to work alongside advanced machine learning approaches. It is difficult to identify a biological marker of disease when the traditional diagnostic labels themselves are not necessarily valid.

We worked with T1 structural magnetic resonance imaging data collected from 1493 individuals comprising healthy control subjects, patients with psychosis, and their unaffected first-degree relatives. Specifically, the dataset included 176 bipolar disorder probands, 134 schizoaffective disorder probands, 240 schizophrenia probands, 362 control subjects, and 581 patient relatives. We assumed that there might be noise in the diagnostic labeling process. We detected label noise by classifying the data multiple times using a support vector machine classifier, and then we flagged those individuals in which all classifiers unanimously mislabeled those subjects. Next, we assigned a new diagnostic label to these individuals, based on the biologicalile also acknowledging that there are misassignments.Increasingly, data-driven methods have been implemented to understand psychopathology. Language is the main source of information in psychiatry and represents „big data” at the level of the individual. Language and behavior are amenable to computational natural language processing (NLP) analytics, which may help operationalize the mental status examination. In this review, we highlight the application of NLP to schizophrenia and its risk states as an exemplar of its use, operationalizing tangential and concrete speech as reductions in semantic coherence and syntactic complexity, respectively. Other clinical applications are reviewed, including forecasting suicide risk and detecting intoxication. Challenges and future directions are discussed, including biomarker development, harmonization, and application of NLP more broadly to behavior, including intonation/prosody, facial expression and gesture, and the integration of these in dyads and during discourse. Similar NLP analytics can also be applied beyond humans to behavioral motifs across species, important for modeling psychopathology in animal models. Finally, clinical neuroscience can inform the development of artificial intelligence.