Idioventricular low frequency oscillation in QT interval responds univocally to RR confusing kinds of mental stress.
Seventeen male subjects, aged nineteen to twenty, went through a protocol including, while supine, relaxation at rest (10 min) and mental stress (MS) by a Kraepelin (arithmetic) test (5 min), as part of a larger study. With a polygraphic analog recording set-up we also collected a 1 ms - digital facsimile of a lead II-like thoracic ECG with maximum T-wave (Codas, Dataq Instr). Twenty-three stress responses were assigned to three classes according to known cardiotacho-, plethysmo-, and pneumo-graphic marks of "concentrated attention mainly," "emotion," or still "high emotion." During each setting the most stationary 3 min RR epoch in cardiotachogram was selected for joint RR & QT beat-by-beat variability study. RR and QT intervals were detected using a published algorithm. Conventional RR and QT Fourier autospectra were computed, while using RR*QT mean square coherence spectrum we detached the RR-independent, idioventricular (IV) fraction of QT low frequency (LF: 0.04-0.15 Hz) power of variability (IV QT-LF). IV QT-LF responded consistently to varieties of mental stress that confuse RR-LF or let QT-LF unchanged, best witnessing the cortically-issued ventricular adrenergic strain. Indeed, while emotion propels the same way all spectral variables above, concentrated attention increased (Wilcoxon) significantly IV QT-LF only (0.54-0.80 ms2) and decreased RR-LF (715-463 ms2). Findings hold promise of a non-invasive, high resolution Holter based monitoring of sympathetic status of myocardium, robust vis-à-vis of confusion caused by the autonomic interplay at sino-atrial node.
Dincă-Panaitescu
S
S
Department of Cardiovascular Prophylaxy, Institute of Public Health, and Institute of Applied Informatics, AISTEDA University, Bucharest, Romania.
Dincă-Panaitescu
M
M
Achim
A
A
Negoescu
R
R
D000328:Adult; D001143:Arousal / Q000502:physiology*; D001146:Arrhythmia, Sinus / Q000503:physiopathology*; D001288:Attention / Q000502:physiology; D001341:Autonomic Nervous System / Q000503:physiopathology; D002540:Cerebral Cortex / Q000503:physiopathology; D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D004644:Emotions / Q000502:physiology; D005583:Fourier Analysis; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D011340:Problem Solving / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D013315:Stress, Psychological / Q000503:physiopathology*