Beat-to-beat QT interval variability before and after cardiac surgery.
Non-uniform recovery of excitability may be essential in triggering malignant ventricular tachycardia after cardiac surgery. Thirty-five channels ECG was recorded for 6 min in 27 patients before and after heart surgery and in 20 control subjects. Off-line analysis was performed. RR interval duration, RR SD, QT SD and power spectra of RR variability were computed from 256 s stable RR and QT interval series. When compared to controls, patients had decreased RR SD and increased QT SD before surgery (p<0.002 and p<0.0005, respectively); RR SD further decreased and QT SD increased after the surgery (p<0.0001 and p<0.0002, respectively). Increase of QT variability and decrease of RR variability after cardiac surgery may reflect disrupted electrophysiological stability of the myocardium and thus electrophysiological substrate for triggering malignant arrhythmia.
Frljak
S
S
Department of Cardiovascular Surgery, University Medical Center, Zaloska, 7, Ljubljana 1000, Slovenia.
Avbelj
V
V
Trobec
R
R
Meglic
B
B
Ujiie
T
T
Gersak
B
B
D000368:Aged; D000465:Algorithms; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D018780:Body Surface Potential Mapping; D006348:Cardiac Surgical Procedures; D016022:Case-Control Studies; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted