QT/RR coherence is associated with testosterone levels in men with chronic spinal cord injury.
OBJECTIVE
To evaluate the effect of hypogonadism on temporal characteristics of ventricular repolarization (VR) and QT/RR coherence in men with spinal cord injury (SCI).


METHODS
Thirty-four men with SCI (>1 year postinjury) were studied. After clinical evaluation, 20 subjects were diagnosed as hypogonadal and 14 as eugonadal. QT and RT time, heart rate (HR), and Bazett QTc were determined from a digital electrocardiogram during quiet rest and a cold pressor test (CPT). QT/RR coherence was calculated across three spectral frequencies including mean (Mean Coh; 0-0.2 Hz), low (LF Coh; 0.04-0.15 Hz) and high (HF Coh; 0.15-0.40 Hz). Respiration was collected via impedance pneumography.


RESULTS
No statistical differences were observed among demographics. Pairwise comparisons demonstrated a significantly reduced Mean Coh at rest in the hypogonadal group compared to the eugonadal; during the CPT, the hypogonadal group had significantly elevated Mean and HF Coh. No group main effects were observed with analysis of variance. Condition main effects were observed in QT, Mean, LF and HF Coh. Significant group-condition interactions were present in Mean and HF Coh, while trends toward significance were observed on LF Coh, HR, QT and RT. Post-hoc pairwise comparisons revealed that the change from rest to CPT in Mean, LF and HF Coh was significant in the eugonadal group, but not the hypogonadal.


CONCLUSIONS
Hypogonadism in SCI appears to adversely affect temporal VR characteristics independently of QTc. QT/RR coherence suggests an autonomic synergism with testosterone. These findings may represent a pathologic sequelae that precedes the well-documented hypogonadic effects on QTc.
VA RR & D Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peters VA Medical Center, Bronx, NY 10468, USA. michael.lafountaine@va.gov
Michael F
MF
La Fountaine
Jill M
JM
Wecht
Christopher M
CM
Cirnigliaro
Steven C
SC
Kirshblum
Ann M
AM
Spungen
William A
WA
Bauman
D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D002908:Chronic Disease; D004562:Electrocardiography; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007006:Hypogonadism / Q000209:etiology; D008297:Male; D008875:Middle Aged; D013119:Spinal Cord Injuries / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D013739:Testosterone / Q000097:blood*
D013739:Testosterone