?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Methods+of+Assessment+and+Clinical+Relevance+of+QT+Dynamics%0A&rft.creator=Beata%2C+Sredniawa&rft.creator=Agata%2C+Musialik-Lydka&rft.creator=Piotr%2C+Jarski&rft.creator=Anna%2C+Sliwinska&rft.creator=Zbigniew%2C+Kalarus&rft.subject=Indian+Pacing+and+Electrophysiology+Journal&rft.description=The+dependence+on+heart+rate+of+the+QT+interval+has+been+investigated+for+many+years+and+several+mathematical+formulae+have+been+proposed+to+describe+the+QT+interval%2Fheart+rate+(or+QT+interval%2FRR+interval)+relationship.+While+the+most+popular+is+Bazett%E2%80%99s+formula%2C+it+overcorrects+the+QT+interval+at+high+heart+rates+and+under-corrects+it+at+slow+heart+rates.+This+formulae+and+many+others+similar+ones%2C+do+not+accurately+describe+the+natural+behaviour+of+the+QT+interval.+The+QT+interval%2FRR+interval+relationship+is+generally+described+as+QT+dynamics.+In+recent+years%2C+several+methods+of+its+assessment+have+been+proposed%2C+the+most+popular+of+which+is+linear+regression.+An+increased+steepness+of+the+linear+QT%2FRR+slope+correlates+with+the+risk+of+arrhythmic+death+following+myocardial+infarction.+It+has+also+been+demonstrated+that+the+QT+interval+adapts+to+heart+rate+changes+with+a+delay+(QT+hysteresis)+and+that+QT+dynamics+parameters+vary+over+time.+New+methods+of+QT+dynamics+assessment+that+take+into+account+these+phenomena+have+been+proposed.+Using+these+methods%2C+changes+in+QT+dynamics+have+been+observed+in+patients+with+advanced+heart+failure%2C+and+during+morning+hours+in+patients+with+ischemic+heart+disease+and+history+of+cardiac+arrest.+The+assessment+of+QT+dynamics+is+a+new+and+promising+tool+for+identifying+patients+at+increased+risk+of+arrhythmic+events+and+for+studying+the+effect+of+drugs+on+ventricular+repolarisation.%0A&rft.publisher=Indian+Pacing+and+Electrophysiology+Group&rft.contributor=Singh%2C+Balbir&rft.contributor=Lokhandwala%2C+Yash&rft.contributor=Francis%2C+Johnson&rft.contributor=Gupta%2C+Anup&rft.date=2005-07&rft.type=Journal+(Paginated)&rft.type=PeerReviewed&rft.format=text%2Fhtml&rft.identifier=http%3A%2F%2Fcogprints.org%2F4452%2F1%2Fsredniawa.htm&rft.format=application%2Fpdf&rft.identifier=http%3A%2F%2Fcogprints.org%2F4452%2F2%2Fsredniawa.pdf&rft.identifier=++Beata%2C+Sredniawa+and+Agata%2C+Musialik-Lydka+and+Piotr%2C+Jarski+and+Anna%2C+Sliwinska+and+Zbigniew%2C+Kalarus++(2005)+Methods+of+Assessment+and+Clinical+Relevance+of+QT+Dynamics.++%5BJournal+(Paginated)%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F4452%2F