Sammanfattning - Medicinsk teknik

Examensarbete Kristina Willner
730503-7124
1 Innehållsförteckning
Sammanfattning ......................................................................................................... 1
Abstract...................................................................................................................... 2
Förord ........................................................................................................................ 3
1 Innehållsförteckning ........................................................................................... 4
2 Inledning ............................................................................................................ 7
2.1 Målsättning................................................................................................. 8
2.2 Metod ......................................................................................................... 8
3 Fysiologi............................................................................................................. 9
3.1 Hjärtats anatomi.......................................................................................... 9
3.2 Hjärtcykeln ............................................................................................... 10
3.3 Hjärtmuskulatur ........................................................................................ 10
3.4 Aktionspotential........................................................................................ 11
3.5 Aktiveringsförloppet i en hjärtmuskelcell.................................................. 11
3.5.1 Depolarisation................................................................................... 11
3.5.2 Repolarisation ................................................................................... 12
3.5.3 Refraktärperiod ................................................................................. 12
3.5.4 Hjärtmuskelcellernas kontraktion ...................................................... 12
3.6 Elektrisk Stimulering ................................................................................ 13
3.7 Tröskelvärde ............................................................................................. 13
3.8 Rytmgivare och hjärtats retledningssystem................................................ 13
3.8.1 Sinusknutan....................................................................................... 15
3.8.2 Förmaksdepolarisation ...................................................................... 15
4 Förmaksflimmer ............................................................................................... 17
4.1 Olika typer av förmaksflimmer ................................................................. 18
4.2 Postoperativt förmaksflimmer ................................................................... 18
4.2.1 Allmänt ............................................................................................. 18
4.2.2 Etiologi * .......................................................................................... 19
4.2.3 Prediktiva faktorer............................................................................. 19
4.3 Medicinering av förmaksflimmer .............................................................. 19
5 Teknisk Bakgrund............................................................................................. 21
5.1 Overdrive pacing....................................................................................... 21
5.2 Hjärtdefibrillering ..................................................................................... 21
5.2.1 Olika vågformer vid elkonvertering................................................... 23
5.3 Elektroder ................................................................................................. 24
5.3.1 Polarisation ....................................................................................... 24
5.3.2 Polarisationsförluster......................................................................... 25
5.3.3 Strömtäthetens betydelse för tröskelvärdet......................................... 27
5.3.4 Vävnadsreaktionens betydelse för tröskelvärdet................................. 27
5.3.5 Elektrodytans betydelse för tröskelvärdet .......................................... 28
5.3.6 Elektrodmaterial................................................................................ 28
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