?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=https%3A%2F%2Fdoktori.bibl.u-szeged.hu%2Fid%2Feprint%2F12417%2F&rft.title=Absolute+beat-to-beat+variability+and+instability+parameters+of+ECG+intervals+predict+ischemia-induced+ventricular+fibrillation&rft.creator=+Sarusi+Annam%C3%A1ria&rft.subject=03.02.04.05.+Ritmuszavarok&rft.subject=03.02.04.06.+Biomarkerek&rft.description=Background%3A+ECG+interval+measurement+is+possible+during+arrhythmias.+Beat-to-beat+variability+and+instability+(BVI)+of+ECG+intervals+measured+irrespective+of+rhythm+(absolute+BVI)+predict+drug-induced+torsades+de+pointes+(TdP)+more+accurately+than+the+same+variables+derived+exclusively+during+sinus+rhythm+(sinus+BVI)+in+rabbits.+We+have+tested+whether+this+approach+predicts+another+stochastic+arrhythmia+event%2C+ventricular+fibrillation+(VF)%2C+in+a+different+pathophysiological+setting.%0D%0A%0D%0AMethods+and+Results%3A+Langendorff+perfused+rat+hearts+were+subjected+to+regional+ischemia+for+15+min.+Absolute+BVI+parameters+were+derived+from+ECG+intervals+measured+in+40+consecutive+ventricular+complexes+(irrespective+of+the+rhythm)+immediately+preceding+VF+onset+and+compared+with+values+in+time-matched+ECGs+in+hearts+that+did+not+express+VF.+Increased+frequency+of+non-sinus+beats+and+%E2%80%98R+on+T%E2%80%99+arrhythmic+beats%2C+shortened+mean+RR+and+electrical+diastolic+intervals%2C+and+increased+BVI+of+cycle+length+and+repolarization+were+associated+with+VF+occurrence.+Absolute+BVI+parameters+that+quantify+variability+of+repolarization+(e.g.+%E2%80%98short-term+variability%E2%80%99+of+QT+interval)+had+the+best+predictive+power+with+very+high+sensitivity+and+specificity.+In+contrast%2C+VF+was+not+predicted+by+any+BVI+parameter+derived+exclusively+from+sinus+rhythm.%0D%0A%0D%0AConclusions%3A+The+novel+absolute+BVI+parameters+that+predicted+TdP+liability+in+rabbits+also+predict+VF+liability+during+regional+ischemia+in+rat+hearts%2C+indicating+a+diagnostic+and+mechanistic+congruence.+Repolarization+inhomogeneity+appears+to+play+a+pivotal+role+in+ischemic+VF+induction+since+absolute+BVI+parameters+that+quantify+repolarization+variability+had+outstanding+predictive+power.&rft.date=2025&rft.type=Disszert%C3%A1ci%C3%B3&rft.type=NonPeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=https%3A%2F%2Fdoktori.bibl.u-szeged.hu%2Fid%2Feprint%2F12417%2F1%2FSarusi%2520Annamaria%2520dissertation.pdf&rft.format=application%2Fpdf&rft.language=en&rft.identifier=https%3A%2F%2Fdoktori.bibl.u-szeged.hu%2Fid%2Feprint%2F12417%2F2%2FSarusi%2520Annam%25C3%25A1ria%2520thesis%2520eng.pdf&rft.format=application%2Fpdf&rft.language=hu&rft.identifier=https%3A%2F%2Fdoktori.bibl.u-szeged.hu%2Fid%2Feprint%2F12417%2F3%2FSarusi%2520Annamaria%2520thesis%2520hun.pdf&rft.format=application%2Fpdf&rft.language=en&rft.identifier=https%3A%2F%2Fdoktori.bibl.u-szeged.hu%2Fid%2Feprint%2F12417%2F4%2FAbsolute%2520beat-to-beat%2520variability%2520and%2520instability%2520parameters%2520of%2520ECG%2520intervals%2520predict%2520ischemia-induced%2520ventricular%2520fibrillation.pdf&rft.identifier=+++Sarusi+Annam%C3%A1ria%0A+++Absolute+beat-to-beat+variability+and+instability+parameters+of+ECG+intervals+predict+ischemia-induced+ventricular+fibrillation.%0A++Doktori+%C3%A9rtekez%C3%A9s%2C+Szegedi+Tudom%C3%A1nyegyetem+(2000-).+%0A(2025)+++++&rft.language=eng