Curve registration for study of P-wave morphing during exercise
The P-wave shape analysis remains an interesting objective in various situations. In this paper, the aim is to investigate how the P-wave morphology changes during time-varying effort. To perform this task, a method, Self-Modeling Registration (SMR), derived from the Curve Registration (CR) theory is used. This method permits to link different shapes by mean of time warping functions. First, using the SMR method, significant P-wave shapes are extracted from two ECG records under maximal and graded exercise test where the effort is released abruptly. Then, the selected shapes are linked by warping functions estimated by SMR method. The obtained warping functions show a reversible evolution of the P-wave shape independently of the possible superimposition of the T-wave. To give a physiological explanation of this P-wave morphing, an atrial contribution evolution scenario under exercise is proposed and validated by simulation.
Integrated shape averaging of the P-wave applied to AF risk detection
The recognition of patients with atrial fibrillation (AF) risk, from body surface ECG, remains an actual problem. The aim of the work is to investigate how the study of the P-wave morphology may assess any clustering algorithm in separating patients with AF risk from healthy subjects. The clustering is done by the k-means algorithm and using a new method: the integrated shape averaging (ISA). According to the results, the method was able to separate patients with AF risk from safety ones with 75 % sensitivity and 70 % specificity on 40 recordings. Furthermore, two families of P-wave patterns were characterized among the patients with AF risk and probably corresponding to electrical manifestations of conduction defects in the left or the right atrium.
Modern Lexicography: An Introduction
Chapter 1: Dictionaries and the Dictionary Chapter 2: The Lexicographical Scene of English-Speaking Countries Chapter 3: The Historical Origins of the General-Purpose Dictionary Chapter 4: General-Purpose Dictionaries and Society Chapter 5: What are General-Purpose Dictionaries Really For? Chapter 6: The Linguistic Traditions ofr Lexicography Chapter 7: Whither Lexicography? Conclusion