Heart ra te correc ti on of t he QT interva l d ur i ng e xercise

Átírás

1 Heart ra te correc ti on of t he QT interva l d ur i ng e xercise Gáb or Andrássy, Attila S zab o, 1 Andrea Duna i, Es zter Sim on, Ádá m T a hy B u d a p e s t i S z e nt Ferenc Kó r há z, K a r d io ló g ia i O s z t á ly, 1 S c ho o l o f B io me d ic a l a nd N a t u r a l S c ie n c e s, N o t t ing ha m T r e nt U n i v e r s it y, N o t t ing h a m, U K L e ve le z é s i c í m: D r. A nd r á s s y G á bo r, S z e nt Ferenc Kó r há z, B u d a p e s t, S z é he r ú t 7 3, H u ng a r y T e le fo n: ( ) , Fa x: ( ) E - ma i l: a n d r a s s y. g a bo o r ha z. d o c c a. hu

2 O b j e c t i v e s : T he u s e o f e x ist ing fo r mu la e t o a d ju s t Q T fo r he a r t r a t e w it h e xe r c is e ma y no t be a p p r o p r ia t e, be c a u s e t he s e fo r mu la e w e r e c o nst r u c t e d b y r e g r e s s i o n a na l ys is o f r e s t ing e le c t r o c a r d io g r a ms. W e p r e s u me, t h a t a n a p p r o p r ia t e me t ho d t o c o r r e ct e xe r c ise e le c t r o c a r d io g r a ms s ho u ld r e mo ve t he d e p e nd e nce o f t he r a t e c o r r e c t e d Q T int e r va l o n h e a r t r a t e, a nd b a s e d o n a v a i la b le d a t a, s ho u ld i n d ic a t e t he s ho r t e n ing o f t he c o r r e c t e d Q T w it h e xe r c is e. T h is s t u d y w a s d e s ig ne d t o e v a lu a t e d if f e r e nt me t ho d s fo r c o r r e c t ing Q T int e r va ls in e xe r c is e e le c t r o c a r d io g r a ms. M e t h o d s : T w e nt y he a lt h y p a r t ic ip a nt s u nd e r w e nt a s u b ma x i ma l 6 - m in u t e B r u c e - P r o t o c o l e xe r c is e t e s t. Q T va lu e s o bt a ine d fr o m t he r e s t a nd e x e r c ise E C G s w e r e c o r r e ct e d fo r he a r t r a t e t hr o u g h t he p r e v io u s l y p u b l is he d B a z e t t, Fr id e r ic ia, S a g ie, H o d g es, a nd Ka r ja la in e n me t ho d s. Fr o m p o o le d QT-RR e xp e r i me nt a l d a t a, w e d e r iv e d a n o p t im iz e d α r e g r e s s io n c o e f f ic ie nt, t ha t yie ld ed o p t im iz e d c o r r e c t io n e q u a t io n ( O P T ) fo r mu la. C o r r e c t e d Q T va lu e s o bt a in e d f r o m r e s t a nd e xe r c is e E C G s w e r e c o mp a r e d, a nd t he c o r r e la t io n be t w e e n he a r t r at e a n d t he c o r r e ct e d Q T int e r va ls w a s a lso s t u d ie d. R e s u l t s : R a w me a s u r e s o f Q T i nt e r va l d e c r e a s e d s ig n if ic a nt ly ( p < ), a n d t he B a z e t t co r r e c t e d Q T s ig n i f ic a nt ly in c r e a s e d ( p = ). T he r e s u lt s ba s e d o n t he o t he r fo u r pr e v io u s l y p u b l is h e d me t ho d s y ie ld e d no n - s ig n i f ic a nt c ha ng e s i n t he r e s t - to-exercise Q T int e r va ls, w he r e a s O P T fo r mu la ind ic a t e d s ig n i f ic a nt Q T s ho r t e n in g ( p = ). C o n c l u s i o n : Fr o m p r e v io u s l y p u b l is h e d me t ho d s, t he u s e o f Fr id e r ic ia, S a g ie, H o d g es a n d Ka r ja la in e n fo r mu la e ma y be u s e f u l fo r a d ju s t in g Q T fo r he a r t r at e w it h e x e r c ise, t ho u g h a n o p t im iz e d fo r mu la f r o m p o o le d d a t a is mo r e - 2 -

3 a p p r o p r ia t e. B a z e t t e q u a t io n y ie ld s s ma l l bu t s ig n i f ic a nt in c r e a s e s d u e t o o ve r c o r r e ct io n, t ha t s ho u ld b e t a k e n int o co ns id e r a t io n in e x e r c ise s e t t ing s. A Q T - id ő fr e k ve nc ia - k o r r e k c ió ja t e r he lé s k o r. C é l k i t ű z é s : A z is mert k o r r e k c ió s k é p le t e k a lk a l ma s s á g a a t e r he lé s a la t t i E K G - k QT-idejének fr e k ve nc ia - k o r r e k c ió já r a k é r d é s e s, m iv e l a z o k a t n yu g a l mi E K G - k r e g r e s s z ió s v iz s g á la t á va l k é s z ít e t t é k. Fe lt é t e le z z ü k, ho g y e g y jó l mű k ö d ő k o r r e k c ió s k é p le t me g s z ü nt e t i a k o r r ig á lt Q T - id ő fr e k ve n c ia - f ü g g é s é t, é s a r e nd e lk e z é s r e á l ló a d a t o k a la p já n a k o r r ig á lt Q T - id ő t e r he lé s r e t ö r t é nő me g r ö v id ü lé s é t mu t a t ja. V iz s g á la t u nk b a n k ü lö n f é le mó d s z e r e k e t ha s o n l ít o t t u nk ö s s z e t e r he lé s e s E KG - k Q T - id e jé n e k k o r r e k c ió já r a. M ó d s z e r e k : 2 0 e g é s z s é g e s v iz s g á la t i s z e mé l y B r u c e p r o t o ko l l s z e r int, 6 - p e r c e s t e r he lé s e s v iz s g á la t ba n v e t t r é s z t. A n yu g a l m i é s a t e r he lé s e s E KG - k QT-időit a k o r á bba n k ö z ö lt B a z e t t, Fr id e r ic ia, S a g ie, H o d g es, é s Ka r ja la in e n mó d s z e r e k s z e r int k o r r ig á lt u k. A k ísér le t Q T / R R a d a t a i a la p já n o pt ima l iz á lt α r e g r e s s z ió s e g yü t t ha t ó va l e g y ú j fo r mu lá t is k é s z ít e t t ü nk ( O P T ). Ö s s z e ha s o n l ít o t t u k a n yu g a l m i é s t e r he lé s a la t t k é s z ít e t t E KG - k k o r r ig á lt QT-időit, va la m int me g v iz s g á lt u k a s z ív f r e k v e nc ia é s a k o r r ig á lt Q T - id ő k k ö z ö t t i ö s s z e fü g g é s t. E r e d m é n y e k : A k o r r ig á la t la n Q T - id ő s z ig n i f ik á n s a n me g r ö v id ü lt ( p < ) é s a B a z e t t s z e r int k o r r ig á lt Q T - id ő s z ig n i f ik á n s a n me g n yú lt ( p = ). A t ö bb i k o r á b ba n k ö z ö lt e ljá r á s a la p já n a Q T - id ő t e r he lé s a la t t ne m vá lt o z o t t s z ig n i f ik á n s a n, m íg a z O P T k é p le t s z ig n i f ik á n s Q T - r ö v id ü lé s t ig a z o lt ( p = ). K ö v e t k e z t e t é s e k : A k o r á bb a n k ö z ö lt fo r mu lá k k ö z ü l a Fr id e r ic ia, S a g ie, H o d g es é s - 3 -

4 Ka r ja la in e n mó d s z e r h a s z no s le h e t a t e r he lé s e s E KG - k Q T - id e jé ne k fr e k ve n c ia - k o r r e k c ió já r a is, he l ye s e b b a z o n ba n, h a e g y a z a d o t t e s e t r e o pt ima l iz á lt k é p le t e t ha s z ná lu n k. A B a z e t t fo r mu l a t ú lk o r r e k c ió mia t t s z ig n if ik á ns Q T - me g n yú lá s t mu t a t ha t, a mit a lk a l ma z á s a k o r f ig ye le mb e k e l l ve n n i. K u l c s s z a v a k : E KG, Q T int e r va l lu m, f iz ik a i t r é n in g K e y w o r d s : E C G, Q T int e r v a l, p h ys ic a l t r a in in g I N T R O D U C T I O N H e a r t r at e p la ys a s u b s t a nt ia l r o le in t he v a r ia t io n o f t h e le ng t h o f t he Q T int e r va l. I n a n e f fo r t t o c o r r ec t fo r t h is e f f e c t, a nd t o ma k e it p o s s ib le t o c o mp a r e Q T int e r va l s o bt a in e d a t d if f e r e nt c yc l e le ng t h s ( R R ), a r a t e no r ma l iz e d Q T is u s e d. T he o b je c t o f a p p l y i n g t h is c o r r e c t io n is t o no r ma l iz e t h e Q T a t a g iv e n h e a r t r a t e t o t he va lu e t ha t it w o u ld ha v e h a d a t a r a t e o f 6 0 be a t s / min. M a n y e q u a t io ns ha v e b e e n d e ve lo p e d fo r Q T c o r r e c t io n. I n g e ne r a l, t he s e ha v e b e e n c o nst r u c t e d b y u s i n g r e g r e s s io n a n a l ys is o f Q T ve r s u s RR ( o r he a r t r at e ) p lo t s, a nd d e s ig n e d t o a llo w t he c a lc u la t io n o f t he c o r r e ct e d Q T ( Q T c ) fo r a n y R R. F o r me r s t u d ie s d id no t inc lu d e he a r t r at e a c h ie ve d w it h e xe r c is e in t he ir mo d e ls ; t he r e fo r e t he u s e o f e x ist ing e q u a t io n s fo r c o r r e c t ing Q T va lu e s a t d if f e r e nt he a r t r a t e s w it h e x e r c is e ma y no t be c o r r e c t. Fu r t he r, i n c l in ic a l p r a c t ic e, t he d if f e r e nt c lin ic a l s it u a t io n s e n c o u nt e r e d ma y r e q u ir e d i f f e r e nt c o r r e ct io n a p p r o a c he s. T he a u t o no mic a nd o t he r p h ys io lo g ic a l r e f le xe s t ha t le a d t o a n in c r e a s e d he a r t r a t e a r e l ik e l y t o in f lu e n c e c a r d ia c r e p o la r isat io n - 4 -

5 d ir e c t ly. T he va r io u s mixt u r e s a nd ba la n c e s o f r e f le x e s in vo lv e d in d if f e r e nt s it u a t io ns t ha t le a d t o a n inc r e a s e d h e a r t r a t e ma y a lt e r t he r e la t io n b e t w e e n t he R R a nd t he Q T int e r va l, e ve n in t he s a m e in d iv id u a l w he n s u b je c t e d t o d iffer e nt h e a r t r a t e p r o vo c at io ns. H e a r t r a t e inc r e a s e r e s u lt in g fr o m p h ys ic a l e xe r c is e, me nt a l s t r e s s, p a c in g, o r p ha r ma c o lo g ic a l a g e nt s m a y le a d t o d iffer e nt s ha p e s o f t he Q T / R R r e la t io n. O u r a im in t h is s t u d y w a s t o t e s t t he a p p r o p r ia t e ne s s o f s o me p r e v io u s l y p u b l is h e d a nd fr e q u e nt ly u s e d h e a r t r at e co r r e ct io n fo r mu la e t o a d ju s t Q T int e r va ls d e r iv e d fr o m e xe r c is e E C G s o f he a lt h y a d u lt s. We a lso c r e a t e d a n o pt im iz e d c o r r e c t io n e q u a t io n ( O P T ) t ha t w a s d e r iv e d fr o m t he p o o le d s t u d y d a t a. O P T me t ho d w a s a lso t e s t e d a nd c o mp a r e d w i t h t he p r e v io u s l y p u b l is h e d e q u a t io ns. M E T H O D S > Fr o m 3 0 he a lt h y vo lu nt e e r s e nr o lle d in t he s t u d y, 2 0 ( 1 4 me n) ha d e xe r c is e E C G s s u it a b le fo r q u a l it y a na l ys is. T he ir a g e s r a ng e d fr o m 2 1 t o 7 3 ( 4 4 ± 1 5 ) ye a r s. A l l s u b je c t s h a d no r ma l s t a nd a r d E C G a nd no s t r u c t u r a l h e a r t d isea s e a s d o c u me nt e d b y me d ic a l h ist o r y, p h ys ic a l e xa m in a t io n, a nd e c ho c a r d io g r a p h y. T he s t u d y w a s a p p r o v e d b y t he I nst it u t io n a l R e v ie w B o a r d a nd w r it t e n in fo r me d c o ns e nt w a s o bt a in e d. A l l s u b je c t s u nd e r w e nt a s t a nd a r d 6 - min u t e B r u c e p r o t o co l t r e a d mi l l s t r e s s t e s t. S imu lt a n e o u s le a d E C G s w e r e r e c o r d e d e v e r y t w o min u t e s a t a p a p e r s p e e d o f 2 5 m m/ s a nd a mp l i f ie r g a in o f 1 0 m m/ mv o n a M a r q u e t t e M a c V U e le c t r o c a r d io g r a p h - 5 -

6 ( M a r q u e t t e E le c t r o n ic s I nc., M i lw a u k e e, W isco n s in, U S A). B e s id e s ba s e l in e r e s t ing E C G s, e x e r c ise E C G s o bt a ine d a t 2 -, 4 -, a nd 6 - m in u t e s w e r e s e le c t e d fo r fu r t h e r a na l ys is. T he p a p e r r e c o r d ing s w e r e t he n s c a n ne d a t h ig h r e s o lu t io n ( d p i) t o a n i ma g e f i le t ha t w a s int e r a c t ive l y a na l yz e d b y m e a ns o f a n in - ho u s e s o ft w a r e p a c k a g e. Q T a nd R R int e r va ls o f t hr e e c o n s e c u t iv e s in u s be a t s in le a d V 3 w e r e me a s u r e d a t t hr e e fo ld e n la r g e me nt in a b l in d e d ma n n e r b y a s in g le e xp e r ie nc e d o bser ve r ( G A). Q T int e r va l w a s me a s u r e d f r o m t he be g in n in g o f t he Q R S c o mp le x t o t he e nd o f t he T w a ve, d e f in e d a s a r e t u r n t o t he ba s e l in e. M e a n R R a nd me a n Q T w e r e o bt a in e d fo r e a c h E C G, a nd me a n Q T va lu e s w e r e a d ju s t e d fo r he a r t r at e a c c o r d in g t o B a z e t t s s q u a r e r o o t fo r mu l a ( Q T Bc = Q T / R R 1 / 2 ), t he c u b ic r o o t fo r mu la int r o d u c e d b y Fr id e r ic ia ( Q T Fc = Q T / R R 1 / 3 ), t he lin e a r fo r mu la p r o p o s e d b y S a g ie ( Q T Lc = QT [1 - R R ] ), t he H o d g e s e q u a t io n ( QT H c = Q T ( r a t e 6 0 ) a nd t he no mo g r a m me t ho d ( Q T Nc ) t ha t w a s e la bo r a t e d by Ka r ja la in e n ( 1, 2, 3, 4, 5 ). A s u c c e s s f u l h e a r t r a t e c o r r e c t io n fo r mu la s ho u ld le a d t o QT c va lu e s t ha t a r e in d e p e nd e nt o f t he o r ig in a l R R int e r va l ( o r he a r t r a t e ) va lu e s. S u c h in d e p e nd e nc e c a n be t e s t e d b y c a lc u la t ing t he c o r r e la t io n c o e f f ic ie nt be t w e e n t he c a lc u la t e d QT c a nd o r ig in a l R R int e r va l v a lu e s. I n t h is s t u d y, t he c o r r e la t io n c o e f f ic ie nt be t w e e n QT c int e r va ls a n d R R int e r v a ls o bt a in e d fr o m e le c t r o c a r d io g r a ms o f a l l t he s u b je c t s w a s c a lc u la t e d f o r e a c h h e a r t r at e c o r r e c t io n fo r mu la. I n a d d it io n, w e a t t e mp t e d t o d e s c r ibe t he Q T / R R r e la t io n s h ip o f o u r d a t a b y c o n s t r u c t ing a d a t a - s p e c if ic, o p t im iz e d c o r r e c t io n - 6 -

7 fo r mu la ( O P T ), t ha t r e f le c t e d t he c ha r a c t e r o f t h is s t u d y g r o u p. U s in g t h e a p p r o a c h d e s c r ib e d b y M a l ik, t he c o f f ic ie nt α fo r O P T w a s d e f in e d fr o m t he g e ne r ic fo r m o f Q T c = Q T / R R α, s u c h t ha t t he c o r r e la t io n c o e f f ic ie nt b e t w e e n Q T c a nd R R int e r v a l w a s z e r o ( 6 ). D a t a a r e e xp r e s s e d a s me a n ± S D. St at ist ic a l a na l ys is w a s p e r fo r me d u s in g G r a p hp a d P r is m ve r s io n fo r W in d o w s, G r a p hp a d S o ft w a r e, S a n D ie g o, C a li fo r n ia, U S A. T h e me a n s s t u d ie d w e r e a s s e s s e d b y r e p e a t e d me a s u r e me nt s a na l ys is o f va r ia n c e ( AN O V A) ; p o s t ho c in t r a g r o u p c o mp a r iso n s w e r e p e r fo r me d u s in g t h e B o n f e r r o n i t e s t. A p va lu e < w a s r e g a r d e d a s s t a t ist ic a l l y s i g n i f ic a nt. R E S U L T S R e s t a nd e xe r c is e v a lu e s o f t he s t u d ie d v a r ia b le s a r e s u m ma r iz e d in t a b l e 1. W it h e x e r c ise, h e a r t r a t e s ig n i f ic a nt ly in c r e a s e d, a n d t he u n c o r r e c t e d Q T int e r va l d u r a t io n s ig n if ic a nt ly s ho r t e ne d. Fr o m t he c o r r e c t e d Q T va lu e s, Q T Bc w a s s ig n if ic a nt ly p r o lo ng e d, w h e r e a s t he o t he r fo u r p r e v io u s l y p u b l is he d me t ho d s y ie ld e d no n s ig n i f ic a nt c ha ng e s. M o r e s p e c if ic a ll y, QT Fc a nd QT L c v a lu e s t e nd e d t o d e c r e a s e, b u t Q T H c a nd Q T Nc r e ma in e d v ir t u a ll y s t a b le t hr o u g ho ut t he p r o t o co l ( f i g u r e s 1 a n d 2 ). An o p t im iz e d va lu e o f fo r t he nu me r ic a l c o e f f ic ie nt α r e s u lt ed in t h e QT O P T c = QT/RR e q u a t io n. U s in g O P T fo r mu la, a s ig n if ic a nt s ho r t e n in g o f t he c o r r e c t ed Q T int e r va l d u r in g e xe r c is e w a s d e t e c t e d. C o r r e la t io n a n a l ys is o f R R a nd QT c d a t a g ive n b y e a c h c o r r e c t io n me t ho d r e ve a le d t ha t o n ly t he ne w l y d e f i n e d O P T e q u a t io n e l i m in a t e d c o mp le t e l y t he he a r t r at e d e p e nd e nc e o f Q T c - 7 -

8 ( ne a r - z e r o c o r r e la t io n : r = ), a nd t he c o r r e la t io n c o e f f ic ie nt s o f t he p r e v io u s l y p u b l is h e d me t ho d s w e r e c o n s id e r a b l y d if f e r e nt fr o m z e r o ( r = fo r B a z e t t, r = fo r Fr id e r ic ia, r = fo r S a g ie, r = fo r H o d g e s, a nd r = fo r Ka r ja la in e n ). D I S S C U S S I O N G r a d e d e xe r c is e le a d s t o s ymp a t h e t ic o ve r d r iv e, a c id o s is, a nd in c r e a s e d bo d y t e mp e r a t u r e w h ic h t r ig g e r va r io u s p h ys io lo g ic a l r e f le xe s. C o n s e q u e nt l y, t h e me c h a n is ms l in k in g t he r e p o la r is a t io n d u r a t io n t o he a r t r at e a r e u n lik e l y t o r e ma in s t a b le d u r ing t he e nt ir e p e r io d o f e xe r c is e. H e a r t r a t e inc r e a s e s li n e a r l y w it h in c r e a s in g w o r k r a t e, a nd s t r o k e vo lu me in c r e a s e s in it ia l l y a t t he o nset o f e x e r c ise, and t he n r e a c h e s a p la t e a u. T he in it ia l in c r e a s e in he a r t r a t e is me d ia t e d b y va g a l w it hd r a w a l, s u b s e q u e nt in c r e a s e s be in g me d ia t e d a t t he s ino a t r ia l no d e b y s y mp a t he t ic s t imu la t io n t hr o u g h t he c a r d ia c n e r ve s a nd c ir c u la t ing c a t e c ho la m in e s ( 7 ). T ho u g h t he in f lu e n c e o f a u t o no mic ne r vo u s s yst e m o n t h e Q T int e r va l is c u r r e nt ly no t fu ll y u nd e r s t o o d, mo s t hu ma n a nd a n i ma l s t u d ie s ha ve s ho w n t ha t t he s y mp a t he t ic s yst e m e x e r t s a s ho r t e n in g e f f e c t o n r e fr a c t o r y p e r io d s a nd Q T d u r a t io n, w h i le t h e p a r a s y mp a t h e t ic s yst e m p r o lo ng s bo t h t he s e va r ia b le s ( 8, 9 ). I t w a s a lso r e p o r t e d t ha t in p a t ie nt s w it h h ig h d e g r e e a t r io ve nt r ic u la r b lo c k t r e a t e d w it h f ix e d r a t e ve nt r ic u la r p a c in g, p h ys ic a l s t r e s s ( e xe r c is e ) in d u c e s s ig n i f ic a nt Q T int e r va l s ho r t e n in g ( 1 0 ). B a s e d o n t he s e e x p e r ime nt a l a nd c l in ic a l d a t a w e h yp o t he s iz e d t ha t, in no r ma l s u b je c t s, a n a p p r o p r ia t e Q T int e r va l c o r r e c t io n - 8 -

9 me t ho d w o u ld in d ic a t e t he s ho r t e n ing o f t h e Q T c w it h e xe r c is e, a nd t ha t a n y me t ho d s ho w ing QT c p r o lo ng a t io n s ho u ld h a ve b e e n been c le a r l y r e g a r d e d a s in a d e q u a t e. Fu r t he r mo r e, t he a p p r o p r ia t e me t ho d s ho u ld t o t a ll y r e mo ve t h e d e p e nd e nc e o f Q T c o n h e a r t r a t e, in o t he r w o r d s, t he c o r r e la t io n be t w e e n he a r t r at e a nd Q T c s ho u ld be z e r o. I n o u r s t u d y, B a z e t t va lu e s in c r e a s e d, Ka r ja la in e n a nd H o d g e s va lu e s r e ma in e d c o nst a nt, a nd in accordance w it h o t he r s, w e fo u n d t ha t Fr id e r ic ia a nd S a g ie c o r r e c t e d Q T int e r v a ls d e c r e a s e d w it h e x e r c ise ( 11, 1 2 ). I n t h is s t u d y, a n o pt im iz e d c o r r e c t io n fo r mu la d e r ive d fr o m o u r e xe r c is e d a t a s e t y i e ld e d t he b e s t r e s u lt s ; be s id e s s ho w ing t h e e xp e c t e d Q T c s ho r t e n in g w it h e xe r c is e, O P T fo r mu la c o mp le t e l y r e mo ve d t he d e p e nd e nc y o f Q T c o n h e a r t r at e. C O N C L U S I O N S T he p r a c t ic a l me a n in g o f Q T int e r v a l me a s u r e me nt s o n e xe r c is e d e p e nd s o n t h e c o r r e c t io n fo r mu la u s e d. T he B a z e t t fo r mu la w ill p r o ba b l y r e ma in in r o u t in e c l in ic a l u s e, bu t it s ho u ld b e no t e d t ha t a n yt i me w he n h e a r t r a t e in c r e a s e s, t h e B a z e t t me t ho d w il l p r o ba b l y s ho w a n a r t ific ia l QT c p r o lo ng a t io n. T ho u g h t he Fr id e r ic ia a n d S a g ie me t ho d s a p p e a r mo r e s u it a b le in e x e r c ise c o nd it io ns, r e lia b le r e s u lt s c a n o n l y b e o bt a ine d, in e a c h c a s e, b y f it t ing t h e c o r r e ct io n me t ho d t o t he s t u d ie d d a t a s e t. A C K N O W L E D G E M E N T W e t ha nk É va B e n k e fo r he r e xc e l le nt t e c hn ic a l a s s ist a n c e

10 R E F E R E N C E S 1. B a z e t t H C. An a na l ys is o f t ime r e la t io ns o f e le c t r o c a r d io g r a m. H e a r t ; 7 : Fr id e r ic ia L S. D ie S yst o le nd a u e r im E le k t r o k a r d io g r a mm b e i no r ma le n M e n s c he n u nd be i H e r z k r a nk e n. Ac t a M e d S c a n d 1920; 53: S a g ie A, L a r s o n M G, G o ld be r g R J, e t a l. A n i mp r o v e d me t ho d fo r a d ju s t ing t he Q T int e r v a l fo r he a r t r at e ( t he Fr a m in g ha m H e a r t St u d y). A m J C a r d io l ; 70: H o d g e s M, S a le r no Q, E r lie n D. B a z e t t s Q T c o r r e c t io n r e v ie w e d. E v id e nc e t ha t a lin e a r Q T c o r r e c t io n fo r he a r t r a t e is be t t e r. J A m C o ll C a r d io l ; 1 : Ka r ja la in e n J, V iit a s a lo M, M a nt t a r i M, e t a l. R e la t io n be t w e e n Q T int e r va ls a nd he a r t r at e s fr o m 4 0 t o be a t s / min in r e s t e le c t r o c a r d io g r a ms o f me n a nd a s i mp le me t ho d t o a d ju s t Q T int e r va l va lu e s. J A m C o ll C a r d io l ; 23: M a l ik M. P r o b le ms o f he a r t r a t e c o r r e c t io n i n a s s e s s me nt o f d r u g - ind u c e d Q T int e r v a l p r o lo ng a t io n. J C a r d io v a s c E le c t r o p h ys io l ; 1 2 : R o w e ll L B. H u ma n c a r d io va s c u la r c o nt r o l. N e w Y o r k : O x fo r d U n iv e r s it y P r e s s ; B r o w ne K F, Z ip e s D P, H e g e r J J, e t a l. I n f lu e nc e o f t he a u t o no mic ne r vo u s s yst e m o n t he Q T int e r v a l. A m J C a r d io l ; 5 0 : B e xt o n R S, V a ll in H O, C a m m A J. D iu r na l va r ia t io n o f t he Q T int e r va l - in f lu e n c e o f t he a u t o no mic ne r vo u s s yst e m. B r H e a r t J ; 5 5 :

11 10. H e d ma n A, N o r d la n d e r L. C ha ng e s i n Q T a nd Q - a T int e r va l s in d u c e d b y me nt a l a nd p h ys ic a l s t r e s s w it h f ix e d r a t e a nd a t r ia l t r ig g e r e d v e nt r ic u la r in h ib it e d c a r d ia c p a c in g. P a c in g C lin E le c t r o p h ys io l ; 1 1 : M a yu g a K A, P a r k e r M, S u k t ha nk e r N D, e t a l. E f f e c t s o f a g e a nd g e nd e r o n t he Q T r e s p o n s e t o e xe r c is e. A m J C a r d io l 2001; 87: A yt e mir K, M a a r o u f N, G a lla g he r M M, e t a l. C o mp a r iso n o f fo r mu la e fo r h e a r t r a t e c o r r e c t io n o f Q T int e r va l in e xe r c is e e le c t r o c a r d io g r a ms. P a c in g C l in E le c t r o p h ys io l ; 22:

12 T a b l e 1. C o m p a ri s o n o f h e a rt ra t e a n d Q T i n t e rv a l v a lu e s o f 2 0 s u b j e c t s a t re s t a n d d u ri n g e xe r c i s e. D a t a a re e xp r e s s e d a s m e a n s ± S D, 1 a l l, 2 re s t v s. o t h e r 3 g ro u p s, 3 re s t v s. 6 - m i n a n d 2 - m i n v s. 6 - m i n. rest 2-min 4-min 6-min p Heart rate (beats/minute) 66±10 80±14 90±17 99±14 < Uncorrected QT (ms) 381±44 362±4 345±44 327±40 < Bazett (ms) 398±46 414±49 419±51 418± Fridericia (ms) 392±43 396±44 393±45 385±48 ns Sagie (ms) 393±43 397±41 393±40 385±40 ns Hodges (ms) 392±42 396±42 397±41 397±44 ns Karjalainen (ms) 394±42 393±41 397±39 393±43 ns OPT (ms) 391±43 392±44 387±45 378±

13 QT (ms) F i g u re 1. R e la t i o n s h i p b e t w e e n h e a rt ra t e, u n c o r r e c t e d Q T a n d QT Bc d u ri n g e x e rc i s e i n h e a lt h y s u b j e c t s. A s i g n i f i c a n t n e g a t i v e ( Q T ) a n d p o s i t i v e ( Q T Bc ) c o r r e la t i o n w a s f o u n d w i t h h e a rt ra t e ( p < a n d p = ) QT QT Bc Heart rate (beats/min)

14 corrected QT (ms) F i g u re 2. M e a n Q T c v a lu e s g i v e n b y d i f f e r e n t c o r re c t i o n m e t h o d s a r e p lo t t e d a g a i n s t h e a rt r a t e s m e a s u r e d a t r e s t a n d a t 2 - m i n, 4 - m i n a n d 6 - m i n d u ri n g e xe r c i s e. A s i g n i f i c a n t Q T c p ro lo n g a t i o n i s i n d i c a t e d b y t h e B a ze t t f o r m u la ( p = ), w h e re a s F ri d e ri c i a, S a g i e, H o d g e s a n d K a rj a la i n e n m e t h o d s s h o w n o s i g n i f i c a n t c h a n g e. O P T f o r m u la d e ri v e d f ro m p o o le d s t u d y d a t a s h o w s i g n i f i c a n t Q T c s h o rt e n i n g ( p = ) heart rate (bpm) Bazett Karjalainen Fridericia Sagie Hodges OPT

15 Tesztkérdések 1. Melyik QT korrekciós képlet kidolgozában szerepeltek terheléskor készített EKGk is? a. Bazett b. Fridericia c. Sagie d. Hodges e. Egyik sem Válasz: e 2. Fix frekvenciájú VVI pacemaker-ritmus melletti terheléskor a QT intervallum a. meghosszabbodik b. változatlan marad c. megrövidül Válasz: c 3. Melyik a legtöbb tanulmány szerint a alábbiak közül a legrosszabb korrekciós formula? a. Karjalainen b. Hodges c. Fridericia d. Bazett e. Sagie Válasz: d