A mikrovolt T-hullám-alternáns, angolul microvolt T-wave alternant (µV-TWA), a T-hullám amplitúdójának ütésről ütésre történő mikrovoltszinten mérhető váltakozása. Mivel ez a változás igen kicsi, csak finom, érzékeny digitális jelfeldolgozó technikával mérhető. Jelenlegi álláspont szerint a µV-TWA megjelenése előre jelezheti a letális, malignus kamrai tachyarrythmiák kialakulásának valószínűségét, a hirtelen szívhalál bekövetkeztét. Az elmúlt tíz évben experimentális és klinikai vizsgálatok próbálták magyarázni a µV-TWA kialakulásának patomechanizmusát és a mögöttes sejtszintű folyamatokat. Azonban a mai napig nem sikerült a µV-TWA-t kialakító celluláris folyamatokat megfelelően tisztázni. Összefoglaló tanulmányunkban áttekintjük azokat a témával foglalkozó közleményeket, amelyek a folyamatban szerepet játszó akciós potenciál repolarizációjában fontosak voltak és áttörést jelentettek az elmúlt években. Részletezzük az akciós potenciál és ionáram-fluktuáció, a citoplazmatikus kalciumkoncentráció-szabályozás, a béta-adrenerg receptorok, valamint a connexinek szerepét a µV-TWA és a következményes kamrai tachyarrhythmiák kialakításában. Ismertetjük továbbá a µV-TWA detektálására jelenleg alkalmazott technikákat, azok felhasználási lehetőségeit a hirtelen szívhalál veszélyeztetettségének felmérésében.
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