Assessment of the Cardiac Autonomic Nervous System in Mercury-Exposed Individuals via Post-Exercise Heart Rate Recovery

Abstract

Objective: The aim of this study was to assess exercise heart rate recovery (HRR) indices in mercury-exposed individuals when evaluating their cardiac autonomic function. Subjects and Methods: Twenty-eight mercury-exposed individuals and 28 healthy controls were enrolled. All the subjects underwent exercise testing and transthoracic echocardiography. The HRR indices were calculated by subtracting the first- (HRR1), second- (HRR2) and third-minute (HRR3) heart rates from the maximal heart rate. The two groups were evaluated in terms of exercise test parameters, especially HRR, and a correlation analysis was performed between blood, 24-hour urine and hair mercury levels and the test parameters. Results: The mercury-exposed and control groups were similar in age (37.2 ± 6.6 vs. 36.9 ± 9.0 years), had an identical gender distribution (16 females and 12 males) and similar left ventricular ejection fractions (65.5 ± 3.1 vs. 65.4 ± 3.1%). The mean HRR1 [25.6 ± 6.5 vs. 30.3 ± 8.2 beats per min (bpm); p = 0.009], HRR2 (43.5 ± 5.3 vs. 47.8 ± 5.5 bpm; p = 0.010) and HRR3 (56.8 ± 5.1 vs. 59.4 ± 6.3 bpm; p = 0.016) values were significantly lower in the mercury-exposed group than in the healthy controls. However, there were no significant correlations between blood, urine and hair mercury levels and exercise test parameters. Conclusions: Mercury-exposed individuals had lower HRR indices than normal subjects. In these individuals, mercury exposure measurements did not show correlations with the exercise test parameters, but age did show a negative correlation with these parameters. Therefore, cardiac autonomic functions might be involved in cases of mercury exposure.

Cardiovascular and Biochemical Responses in Exercise Recuperation in Diabetic Rats

“…Although this phase of exercise may be starting to be investigated, the results still diverge about the necessary time to a total restoration to the rest levels after exercise, and the autonomic nervous system (ANS) might be involved in this event [ [19][20][21]. The time spent to the HR to return to resting levels depends on the interaction between the autonomic functions, the level of physical conditioning and the exercise intensity as well [22].…”

Heart Rate Variability, Heart Rate Recovery, and Heart Rate Turbulence Represent Different Components of the Cardiac Autonomic Nervous System

“…I read with great interest the paper by Yilmaz et al [ 1 ] entitled ‘Assessment of the Cardiac Autonomic Nervous System in Mercury-Exposed Individuals via Post-Exercise Heart Rate Recovery’. They aimed to investigate cardiac autonomic function in mercury-exposed individuals by exercise heart rate recovery.…”

“…Heart rate turbulence is the measurement of turbulence onset and turbulence slope according to an algorithm, and describes the return of the heart rate to equilibrium after a premature ventricular contraction [ 1 ]. Impairments on heart rate variability, heart rate turbulence, or heart rate recovery are associated with a greater risk of mortality [ 1 , 2 , 3 , 4 , 5 ]. However, these parameters of heart rate variability, heart rate recovery, and heart rate turbulence stand for different components of cardiac autonomic function.…”

“…I think the discussion of outcomes in the study by Yilmaz et al [ 1 ] might have been more useful if the authors had considered the remarkable difference among heart rate variability, heart rate recovery, and heart rate turbulence measurements. Moreover, it would have been more helpful to perform the study using the combination of heart rate variability, heart rate recovery, and heart rate turbulence for a clearer determination of the mechanism of impairment of cardiac autonomic function in the mercury-exposed individuals.…”

Attenuated Heart Rate Recovery in Mercury-Exposed Individuals

“…We read with great enthusiasm the article by Yilmaz et al [ 1 ] that investigated the heart rate recovery (HRR) of mercury-exposed individuals. They reported that HRR at the first (HRR1), second, and third minute were attenuated in mercury-exposed patients when compared to normal subjects.…”