Chinese expert consensus on the construction of the fluoroless cardiac electrophysiology laboratory and related techniques.

Transcatheter radiofrequency ablation has been widely introduced for the treatment of tachyarrhythmias. The demand for catheter ablation continues to grow rapidly as the level of recommendation for catheter ablation. Traditional catheter ablation is performed under the guidance of X-rays. X-rays can help display the heart contour and catheter position, but the radiobiological effects caused by ionizing radiation and the occupational injuries worn caused by medical staff wearing heavy protective equipment cannot be ignored. Three-dimensional mapping system and intracardiac echocardiography can provide detailed anatomical and electrical information during cardiac electrophysiological study and ablation procedure, and can also greatly reduce or avoid the use of X-rays. In recent years, fluoroless catheter ablation technique has been well demonstrated for most arrhythmic diseases. Several centers have reported performing procedures in a purposefully designed fluoroless electrophysiology catheterization laboratory (EP Lab) without fixed digital subtraction angiography equipment. In view of the lack of relevant standardized configurations and operating procedures, this expert task force has written this consensus statement in combination with relevant research and experience from China and abroad, with the aim of providing guidance for hospitals (institutions) and physicians intending to build a fluoroless cardiac EP Lab, implement relevant technologies, promote the standardized construction of the fluoroless cardiac EP Lab.

Fluoroless catheter ablation of atrial fibrillation: a step-by-step workflow.

Catheter ablation is an important therapeutic strategy for patients with atrial fibrillation (AF). While some critical steps of the procedure have traditionally relied on fluoroscopy, advances in electroanatomic mapping and the growing use of intracardiac echocardiography have made non-fluoroscopic AF ablation a reality. This hands-on review provides an overview on how to perform radiofrequency ablation of AF without the use of fluoroscopy, focusing on technical aspects, new technologies, and troubleshooting.

Safety and efficacy of stereotactic radioablation targeting pulmonary vein tissues in an experimental model.

BACKGROUND: Stereotactic radioablation (SR), a commonly used therapy to treat malignant tumors, has been used to treat refractory ventricular tachycardia, but the feasibility of treating atrial fibrillation with SR is unknown. OBJECTIVE: We evaluated the safety and efficacy of SR targeting pulmonary vein (PV) antral tissues as a potential therapy for atrial fibrillation. METHODS: Seventeen adult canines and 2 adult swine underwent surgical fiducial marker placement, 3-dimensional anatomic rendering computed tomography angiogram of the left atrium, and creation of a treatment plan targeting the right superior PVs. Four treatment doses (15, 20, 25, and 35 Gy) were administered to 4 cohorts. Subjects were monitored for 3-6 months, followed by electrophysiological testing, gross pathological examination, and histopathology in 2 subjects. RESULTS: All subjects received SR treatment without complication. Electrophysiology study and gross pathological analysis demonstrated treatment effect in all treated PVs at 35 Gy and 25 Gy (n = 11 of 11 [100%]), with a partial effect at 20 Gy (n = 4 of 5 [80%]; 1 did not undergo repeat electrophysiology study) and 15 Gy (n = 1 of 2 [50%]). No evidence of collateral injury was found in tissues directly adjacent to the treated PVs. In 2 subjects, detailed histopathology demonstrated evidence of circumferential, transmural scar at the PV ablation sites, with sparing of the surrounding structures. CONCLUSIONS: SR is safe and effective for creating precise circumferential scar and electrical isolation of the right superior PV in an experimental model, with dose dependence between delivered radioablative energy and observed electrical effects.

Independent mapping methods reveal rotational activation near pulmonary veins where atrial fibrillation terminates before pulmonary vein isolation.

OBJECTIVE: To investigate mechanisms by which atrial fibrillation (AF) may terminate during ablation near the pulmonary veins before the veins are isolated (PVI). INTRODUCTION: It remains unstudied how AF may terminate during ablation before PVs are isolated, or how patients with PV reconnection can be arrhythmia-free. We studied patients in whom PV antral ablation terminated AF before PVI, using two independent mapping methods. METHODS: We studied patients with AF referred for ablation, in whom biatrial contact basket electrograms were studied by both an activation/phase mapping method and by a second validated mapping method reported not to create false rotational activity. RESULTS: In 22 patients (age 60.1 ± 10.4, 36% persistent AF), ablation at sites near the PVs terminated AF (77% to sinus rhythm) prior to PVI. AF propagation revealed rotational (n  =  20) and focal (n  =  2) patterns at sites of termination by mapping method 1 and method 2. Both methods showed organized sites that were spatially concordant (P < 0.001) with similar stability (P < 0.001). Vagal slowing was not observed at sites of AF termination. DISCUSSION: PV antral regions where ablation terminated AF before PVI exhibited rotational and focal activation by two independent mapping methods. These data provide an alternative mechanism for the success of PVI, and may explain AF termination before PVI or lack of arrhythmias despite PV reconnection. Mapping such sites may enable targeted PV lesion sets and improved freedom from AF.

The precise timing of tachycardia entrainment is determined by the postpacing interval, the tachycardia cycle length, and the pacing rate: Theoretical insights and practical applications.

BACKGROUND: Previous observations have reported that the number of pacing stimuli required to entrain a tachycardia varies on the basis of arrhythmia type and location, but a quantitative formulation of the number needed to entrain (NNE) that unifies these observations has not been characterized. OBJECTIVE: We sought to investigate the relationship between the number of pacing stimulations, the tachycardia cycle length (TCL), the overdrive pacing cycle length (PCL), and the postpacing interval (PPI) to accurately estimate the timing of tachycardia entrainment. METHODS: First, we detailed a mathematical derivation unifying electrophysiological parameters with empirical confirmation in 2 patients undergoing catheter ablation of typical atrial flutter. Second, we validated our formula in 44 patients who underwent various catheter ablation procedures. For accuracy, we corrected for rate-related changes in conduction velocity. RESULTS: We derived the equations NNE = |(PPI - TCL)/(TCL - PCL)| + 1 and Tachycardia advancement = (NNE - 1) × (TCL - PCL) - (PPI - TCL), which state that the NNE and the amount of tachycardia advancement on the first resetting stimulation are determined using regularly measured intracardiac parameters. In the retrospective cohort, the observed PPI - TCL highly correlated with the predicted PPI - TCL (mean difference 5.8 ms; r = 0.97; P < .001), calculated as PPI - TCL = (NNE - 1) × (TCL - PCL) - tachycardia advancement. CONCLUSION: The number of pacing stimulations required to entrain a reentrant tachycardia is predictable at any PCL after correcting for cycle length-dependent changes in conduction velocity. This relationship unifies established empirically derived diagnostic and mapping criteria for supraventricular tachycardia and ventricular tachycardia. This relationship may help elucidate when antitachycardia pacing episodes are ineffective or proarrhythmic and could potentially serve as a theoretical basis to customize antitachycardia pacing settings for improved safety and effectiveness.

Electroanatomic localization of a slowly conducting atrioventricular (Mahaim) accessory pathway.

We present a case of a 34-year-old female with Ebstein's anomaly and symptomatic wide complex tachyarrhythmia. Electrophysiologic evaluation demonstrated antidromic tachycardia utilizing a right-sided decremental, slowly conducting atrioventricular pathway. Distinct accessory pathway potentials along the length of the bypass tract were sequentially recorded to define the anatomic course of the pathway, as uniquely represented on a three-dimensional electroanatomic map, and to successfully guide catheter ablation.

Epicardial catheter mapping and ablation of ventricular tachycardia.

Percutaneous entry into the pericardial space allows epicardial catheter mapping and ablation in the electrophysiology laboratory, opening a perspective on cardiac electrophysiology that previously was limited largely to the operating room. Scar-related reentry after myocardial infarction usually involves the subendocardium but in some patients can only be ablated from the epicardium. Epicardial, scar-related reentry also is an important cause of ventricular tachycardia in nonischemic cardiomyopathies. Rare supraventricular tachycardias and idiopathic ventricular tachycardia that cannot be defined from the endocardium sometimes can be ablated from the epicardium. With appropriate precautions the procedural risks are low. Epicardial catheter techniques expand the options for investigating cardiac electrophysiology and treating arrhythmias in humans and may lead to insights into transmural properties influencing repolarization and the genesis of arrhythmias.