Recent Advances in Catheter Ablation for Atrial Fibrillation and Non-pharmacological Stroke Prevention

*Nayanjyoti Kaushik, James Arter Chapman, Andrew Gillaspie, Stephen Ackerman, Peter Gallagher, Deobrat Mallick and Steven J. Bailin*

#### **Abstract**

Atrial Fibrillation is a common arrhythmia affecting 6 million people in the United States and 33 million people worldwide, associated with significant morbidity. Whereas restoration and maintenance of sinus rhythm can translate into clinical benefit, early intervention in course of the disease can influence success and efficacy of intervention has been speculative and uncertain over past decade despite several literature and scientific studies. During past three decades catheter and surgical ablation of AF have evolved from an investigational status to a widely offerred definitive treatment now. With recent advances in mapping technology, ablation energy delivery, better understanding of pathogenesis and mechanism of AF there has been a paradigm shift in clinical decision making, patient selection, patient-physician discussion about various rhythm control strategy due to an ever improving safety and efficacy of the procedure. In this chapter we will briefly review the landmark clinical trials that has changed the outlook towards rhythm control strategy beginning from early trials such as AFFIRM, telling us rhythm control was no better than rate control to recent studies and EAST AFNET, which showed benefits of rhythm control. We will discuss differences in ablation strategy, safety and efficacy between paroxysmal AF vs. Persistent/ Longstanding Persistent AF from a trigger and substrate view and pulmonary vein and non pulmonary vein targets for ablation. We will also elaborate on different energy sources for ablation such as Radiofrequency (RF), Cryoablation, newer ablation techniques such as Vein of Marshall alcohol ablation, High Power short duration ablation, Pulsed Field Ablation, Surgical ablation and Hybrid Convergent Ablation etc. Since this chapter is mostly intended towards diagnosis and management of AF in twenty-first century, authors have restricted mainly to recent developments only and purposefully have not expanded on already established preexisting knowledge about topics such as pharmacological rhythm control, rate control, Atrio-Ventricular node ablation with pacemaker implantation, direct current cardio version etc. In conclusion, with recent emerging evidence, importance of rhythm control is being increasingly recognized. Catheter ablation is more commonly performed with improving

safety and efficacy. There are newer technology and ablation strategy available and should be offered to patient while discussing a comprehensive management of AF with careful review of risk benefit analysis.

**Keywords:** catheter ablation, atrial fibrillation, rhythm control, pulmonary vein isolation, pulse field ablation, vein of marshal, cardioneural ablation, ganglionic plexi, high power short duration, cryoablation, radiofrequency ablation, left atrial appendage occlusion, watchman, stroke prevention


**Qiaorui Si 1, Chunhao Shen 1, Asad Ali 1, Rui Cao 1, Jianping Yuan 1 and Chuan Wang 2,\***

**\*** Correspondence<EMAIL_ADDRESS>Tel.: +86-1505-085-4169

Received: 31 October 2019; Accepted: 25 November 2019; Published: 4 December 2019

**Abstract:** Miniature drainage pumps with a radial blade are widely used in situations with critical constant head and low noise requests, but the stable operation state is often broken up by the entraining gas. In order to explore the internal flow characteristics under gas–liquid two phase flow, pump performance and emitted noise measurements were processed under different working conditions. Three-dimensional numerical calculations based on the Euler inhomogeneous model and obtained experimental boundaries were carried out under different inlet air void fractions (IAVFs). A hybrid numerical method was proposed to obtain the flow-induced emitted noise characteristics. The results show there is little influence on pump characteristics when the IAVF is less than 1%. The pump head slope degradation was found to increase with air content. The bubbles adhere to the impeller hub on the blade's suction side and spread to the periphery with a big IAVF, leading to unstable operation. It is obvious that vortices appear inside the impeller flow passage as IAVF reaches 6.5%. The two-phase flow pattern has a small effect on the characteristic frequency distribution of pressure fluctuation and emitted noise, but the corresponding pulsation intensity and noise level will increase. The study could provide some reference for low noise design of the drainage pump.

**Keywords:** miniature drainage pump; gas-liquid two-phase flow; radiate noise; pressure


**8. Conclusion**

Thalassemia arises from well over 400 mutations that, in the cumulative, affect every step required for successful production of the large amounts of Hb needed for normal red cell homeostasis. The mutations accounting for most of the thalassemia patients around the world are those affecting translation termination and mRNA splicing. Gene deletions and rearrangements, and defects affecting transcription, mRNA stability, or Hb assembly are uncommon or occur rarely.


2.2.3. Land Type Data

ESA CCI-LC land use/cover data (300 m spatial resolution, 1992–2015) were downloaded from the European space agency (http://maps.elie.ucl.ac.be/CCI/viewer/; accessed on 11 January 2022). The ESA data (including 22 categories) were reclassified into 10 categories: agriculture, forest, grassland, wetland, settlement, shrubland, sparse vegetation, bare area, water, and permanent snow and ice (Figure 3).

**Figure 3.** The land-use type maps in the study area.


*2.3. Research Hotspots of China's AI International Research*

In this study, the topics and keywords in the literature were used to explore the hot topics and hotspots of Chinese scholars in the field of AI in 2009–2018. It is generally believed that keywords are highly condensed and concise in the topic and research hotspots; with the assistance of the knowledge map of co-occurrence keywords drawn by CiteSpace software, this study quickly elucidated the structure, network distribution, and frequency of co-occurrence of related articles keywords, so as to clarify the research hotspots in the field [73–76]. Through the visualization analysis of 3577 related papers collected in this paper, a knowledge map of the international research hotspots of China's AI by node type and time-zone type was obtained. The two maps are shown in Figures 2 and 3.

**Figure 2.** The knowledge map of China's international AI research hotspots (node type) (2009–2018).

**Figure 3.** The knowledge map of China's international AI research hotspots (time-zone type) (2009–2018).

The keywords in the knowledge maps shown in Figures 2 and 3 represent the nodes in the network, and the connections between the network nodes represent their co-occurrence relationships. The larger the nodes, the more rings, indicating that the co-occurrence frequency of the keywords is higher. Figure 2 shows that besides the node of "artificial intelligence" (673 times), the nodes with high frequency were "neural network" (307 times), "model" (261 times), "system" (244 times), "optimization" (202 times), "genetic algorithm" (172 times), and "cloud computing" (97 times), etc. Furthermore, new keywords and research hotspots of "China" (32 times), "extreme learning machine" (29 times), "big data" (29 times), "face recognition" (25 times), "electronic skin" (28 times) and other nodes emerged 2015. By reviewing the keywords and subject words that have appeared over the years, the hotspots and interests of Chinese scholars' research on AI can be understood. In the initial exploration stage of AI, Chinese scholars relied on "artificial neural networks" and "genetic algorithms" to conduct research and gradually formed models and systems, and then transferred focus to "cloud computing" and "data sharing" in the steady rising stage. In recent years, hot topics such as "China", "big data", "face recognition", and "electronic skin" have been closely related to the frontier areas of AI, or closely related to current policies and social concerns. In addition, some experts mentioned new functions of AI applications in different fields, such as pattern tracking, data classicization, neural network, deep mining, etc. [85–91], which are worthy of further attention in this study. The organic connection and quantitative comparative analysis between the hot spots of AI international research in the past ten years and policy keywords at the national level is discussed in the following sections.

#### **3. Quantification Analysis of China's AI National-Level Policy Documents**

#### *3.1. Stage Division of China's AI National-Level Policy*

The quantification analysis of policy documents is based on the analysis of policy documents; on the basis of collecting policy documents and constructing subject words, it further integrates the information contained in the documents, and carries out co-occurrence analysis, clustering analysis, and trend evolution analysis of relevant information, keywords and subject words from multiple dimensions and multiple angles. Starting from the quantitative law of inductive document attributes, it puts forward deeper policy suggestions and reflections based on the combination of qualitative and quantitative research [92–95].

This study established a dataset of AI policy analysis. First, based on the word frequency statistics of AI documents, it identified and constructed the list of initial AI keywords, which were mainly about "AI", and "deep learning", "big data", and "cloud computing", etc. The research team further asked experts in the corresponding field to judge and screen the keywords. Based on the keywords, the pre-search was conducted in the Government Documents Information System (GDIS) of the School of Public Policy and Management of Tsinghua University, and the title and text of policy documents containing the above-mentioned search terms were selected and screened. A total of 262 pieces of China's central-level or national AI policy documents were retrieved. The relevant policy documents were initially sorted and classified according to their years of publication, and the policy trend as well as a stage division map was drawn (shown in Figure 4).

**Figure 4.** The trends and stages of China's national-level AI policy (2009–2018). Source: According to References [19,51].

The collection of policy documents and reports, especially the China AI Development Report 2018 and Domestic and Foreign AI Policy Analysis Report 2018 was combined with the three-stage distribution of AI international research hotspots discussed in Section 2. In order to maintain the consistency and contrast of the analysis, this study roughly sorted the national AI policy into three groups: (1) the initial exploration stage of 2009–2012, where there were fewer national-level policies for AI; (2) the steady rising stage of 2013–2015, when the development of AI gradually increased to the level of national strategy, and policy documents were issued more quickly and steadily; and (3) the rapid development stage of 2016–2018, representing the upsurge of AI development, in which the national-level AI policies became more comprehensive, the top-down design was further enhanced, and the follow-up policies and plans at all levels in various fields were more targeted and specific.


**3.2 Research approach**

The design of the survey instrument for this study was based upon an extrapolation of several concepts from the literature review including learning disruption, student resources, assessment effectiveness, and educational outcomes. To ensure comparability, the instrument was structured into multiple sections which included the following core elements:

Where three of the prompts offered write-in responses relating to student experiences during digital learning, the open-ended feedback was aggregated and compared for similar themes. The survey was designed to be administered to students remotely via a dedicated SurveyMonkey link that was standardised and pasted into e-mail communications. The procedure involved identifying a possible sample population, distributing a targeted query letter to students, capturing evidence, and normalising and analysing the findings. The extensive data was analysed categorically to match the research objectives in technological advancement, challenges, and future projections and recommendations,