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Typification of atrial organization in electrogram recordings

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of blood ejected during resting conditions is approximately 5 l/min, with a heart rate of about 70 bpm and a stroke volume of about 70 ml; these number can vary greatly so that the amount of blood pumped could reach values close to, or even exceeding 15 l/min, satisfying the increased metabolic requests of the body under stress conditions. 1.1 The atria The atria represent a crucial element of the normal circulatory functions and regulation. Often atrial dysfunctions precede the onset of AF, so that a better understanding of atrial function and dysfunction is relevant to clinical management of AF and can guide the research on new algorithms which are able to detect, describe and discriminate between different types of the pathology. Even though much progress has been made during the last few decades in understanding the electrophysiology and hemodynamics, atrial contrac- tile function pre-onset and in paroxysmal (non persistent) AF (PAF) is still poorly understood. AF trigger mechanisms are elusive and in some cases unknown, even if both an underlying etiology and an apparently proper pre- cipitating cause are present. 1.1.1 Anatomy The atria are thin-walled and are mainly constituted of muscular tissue, with longitudinally oriented fibers. The right atrium is connected to the venae cavae and is separated from the right ventricle by the tricuspid valve, while the left atrium is connected to the pulmonary veins and divided from the left ventricle by the mitral valve. Both atria have attached appendages named auricles: in particular the left auricle shows a very narrow and elongated structure that, likely, favours thrombus formation if non contracting. The thin structure of atrial walls and the organization of the muscular fibers suggest the atria to be low-pressure chambers: stretch receptors are in fact present as well, with granules releasing a peptide (ANP, atrial natriuretic peptide) that represents a feedback control stadium for volume and pressure overload. Moreover, a specialised conduction tissue is present in the SA and AV nodes in the internodal pathways: both SA and AV nodes are influenced by auto- nomic nerve endings, suggesting some possibilities for neural mechanisms to play a role in the genesis and maintenance of AF. 4

Anteprima della Tesi di Alberto Zaffaroni

Anteprima della tesi: Typification of atrial organization in electrogram recordings, Pagina 2

Laurea liv.II (specialistica)

Facoltà: Ingegneria

Autore: Alberto Zaffaroni Contatta »

Composta da 93 pagine.

 

Questa tesi ha raggiunto 482 click dal 06/12/2005.

Disponibile in PDF, la consultazione è esclusivamente in formato digitale.