[Correlations of thyroid hormone with deceleration capacity of heart rate and heart rate variability in children with hyperthyroidism]

OBJECTIVE

To investigate deceleration capacity of heart rate (DC), acceleration capacity of heart rate (AC), and heart rate variability (HRV) in children with hyperthyroidism and the correlations of serum thyroid hormone levels with DC, AC, and HRV.

METHODS

A total of 47 children with hyperthyroidism were enrolled as hyperthyroidism group and 50 healthy children were enrolled as control group. The subjects in the two groups underwent 24-hour ambulatory electrocardiography. The two groups were compared in terms of DC, AC, heart rate (HR), HRV parameters [standard deviation of normal-to-normal RR intervals (SDNN), standard deviation of average normal-to-normal RR intervals (SDANN), root mean square of successive differences between adjacent RR intervals (RMSSD), low-frequency power (LF), and high-frequency power (HF)]. The correlations of thyroid hormone indices [free triiodothyronine (FT3) and free thyroxin (FT4)] with DC, AC, and HRV were analyzed.

RESULTS

Compared with the control group, the hyperthyroidism group had significantly lower DC, SDNN, SDANN, RMSSD, LF, and HF and significantly higher AC and HR (P<0.05). In the children with hyperthyroidism, serum FT3 and FT4 levels showed significant negative correlation with DC, SDNN, SDANN, RMSSD, LF, and HF and significant positive correlation with AC and HR (P<0.05).

CONCLUSIONS

Children with hyperthyroidism have cardiac autonomic nerve dysfunction manifested as reduced vagal tone. Vagal tone decreases with the increasing serum thyroid hormone levels, suggesting an increased risk of cardiovascular disease.

[Correlations of thyroid hormone with deceleration capacity of heart rate and heart rate variability in children with hyperthyroidism]

OBJECTIVE

To investigate deceleration capacity of heart rate (DC), acceleration capacity of heart rate (AC), and heart rate variability (HRV) in children with hyperthyroidism and the correlations of serum thyroid hormone levels with DC, AC, and HRV.

METHODS

A total of 47 children with hyperthyroidism were enrolled as hyperthyroidism group and 50 healthy children were enrolled as control group. The subjects in the two groups underwent 24-hour ambulatory electrocardiography. The two groups were compared in terms of DC, AC, heart rate (HR), HRV parameters [standard deviation of normal-to-normal RR intervals (SDNN), standard deviation of average normal-to-normal RR intervals (SDANN), root mean square of successive differences between adjacent RR intervals (RMSSD), low-frequency power (LF), and high-frequency power (HF)]. The correlations of thyroid hormone indices [free triiodothyronine (FT3) and free thyroxin (FT4)] with DC, AC, and HRV were analyzed.

RESULTS

Compared with the control group, the hyperthyroidism group had significantly lower DC, SDNN, SDANN, RMSSD, LF, and HF and significantly higher AC and HR (P<0.05). In the children with hyperthyroidism, serum FT3 and FT4 levels showed significant negative correlation with DC, SDNN, SDANN, RMSSD, LF, and HF and significant positive correlation with AC and HR (P<0.05).

CONCLUSIONS

Children with hyperthyroidism have cardiac autonomic nerve dysfunction manifested as reduced vagal tone. Vagal tone decreases with the increasing serum thyroid hormone levels, suggesting an increased risk of cardiovascular disease.

[Effect of vitamin D deficiency on cardiac autonomic nerve function in obese pre-school children]

OBJECTIVE

To study the effect of vitamin D (VitD) deficiency on cardiac autonomic nerve function in obese pre-school children.

METHODS

A total of 242 pre-school children with simple obesity were enrolled, and according to the serum 25-(OH) VitD level, they were divided into VitD deficiency group (76 children), VitD insufficiency group (83 children), and VitD sufficiency group (83 children). The three groups were compared in terms of deceleration capacity (DC) of heart rate, acceleration capacity (AC) of heart rate, and heart rate variability (HRV). The correlations of VitD level with DC, AC, and HRV were analyzed for the VitD insufficiency and VitD deficiency groups.

RESULTS

The VitD deficiency group had the lowest DC, root mean square of successive differences between adjacent RR intervals (RMSSD), and low-frequency power (LF) and the highest AC (P<0.05). The VitD insufficiency group had significantly lower DC, RMSSD, and LF and significantly higher AC compared with the VitD sufficiency group (P<0.05). The VitD deficiency group had significantly lower standard deviation of normal-to-normal RR intervals (SDNN) and high-frequency power (HF) than the VitD sufficiency group (P<0.05). In the VitD deficiency group, VitD level was positively correlated with DC, SDNN, standard deviation of average normal-to-normal RR intervals, RMSSD , LF, and HF and was negatively correlated with AC (P<0.05). In the VitD insufficiency group, VitD level was negatively correlated with AC (P<0.05).

CONCLUSIONS

Obese pre-school children with VitD insufficiency or deficiency have cardiac autonomic dysfunction, and cardiac vagal tone decreases with the reduction in VitD level.

[Effect of vitamin D deficiency on cardiac autonomic nerve function in obese pre-school children]

OBJECTIVE

To study the effect of vitamin D (VitD) deficiency on cardiac autonomic nerve function in obese pre-school children.

METHODS

A total of 242 pre-school children with simple obesity were enrolled, and according to the serum 25-(OH) VitD level, they were divided into VitD deficiency group (76 children), VitD insufficiency group (83 children), and VitD sufficiency group (83 children). The three groups were compared in terms of deceleration capacity (DC) of heart rate, acceleration capacity (AC) of heart rate, and heart rate variability (HRV). The correlations of VitD level with DC, AC, and HRV were analyzed for the VitD insufficiency and VitD deficiency groups.

RESULTS

The VitD deficiency group had the lowest DC, root mean square of successive differences between adjacent RR intervals (RMSSD), and low-frequency power (LF) and the highest AC (P<0.05). The VitD insufficiency group had significantly lower DC, RMSSD, and LF and significantly higher AC compared with the VitD sufficiency group (P<0.05). The VitD deficiency group had significantly lower standard deviation of normal-to-normal RR intervals (SDNN) and high-frequency power (HF) than the VitD sufficiency group (P<0.05). In the VitD deficiency group, VitD level was positively correlated with DC, SDNN, standard deviation of average normal-to-normal RR intervals, RMSSD , LF, and HF and was negatively correlated with AC (P<0.05). In the VitD insufficiency group, VitD level was negatively correlated with AC (P<0.05).

CONCLUSIONS

Obese pre-school children with VitD insufficiency or deficiency have cardiac autonomic dysfunction, and cardiac vagal tone decreases with the reduction in VitD level.

[Cardiac autonomic nerve function in obese school-age children]

OBJECTIVE

To analyze the deceleration capacity (DC) of heart rate, acceleration capacity (AC) of heart rate, and heat rate variability (HRV) in obese school-age children, and to observe the correlations of BMI with DC, AC, and HRV in these children.

METHODS

A total of 108 obese school-age children were selected, including 75 cases of ortholiposis and 33 cases of dyslipidemia. A total of 103 healthy school-age children were selected as control group. All the subjects underwent 24-hour ambulatory electrocardiography. The comparisons of DC, AC, and HRV were made between the obese and control groups, as well as between children with ortholiposis and dyslipidemia in the obese group. The correlations of BMI with DC, AC, and HRV were analyzed in the obese group.

RESULTS

The obese group showed lower DC, standard deviation of normal-to-normal R-R intervals (SDNN), standard deviation of the average normal-to-normal intervals (SDANN), root mean square of successive differences (RMSSD), low-frequency power (LF), and high-frequency power (HF) than the control group. The AC of the obese group was significantly higher than that of the control group (P<0.05). In the obese group, children with dyslipidemia had significantly lower DC, SDNN, SDANN, RMSSD, LF, and HF, but significantly higher AC and BMI, as compared with those with ortholiposis (P<0.01). In the obese group, BMI was negatively correlated with DC, SDNN, SDANN, RMSSD, and HF (P<0.05), but positively correlated with AC (P<0.05).

CONCLUSIONS

Obese school-age children have impaired autonomic nerve function, presenting with reduced vagal tone, which is particularly prominent in those with dyslipidemia. The more obese the children, the lower the vagal tone, which may increase the risks of cardiovascular diseases.

[Cardiac autonomic nerve function in obese school-age children]

OBJECTIVE

To analyze the deceleration capacity (DC) of heart rate, acceleration capacity (AC) of heart rate, and heat rate variability (HRV) in obese school-age children, and to observe the correlations of BMI with DC, AC, and HRV in these children.

METHODS

A total of 108 obese school-age children were selected, including 75 cases of ortholiposis and 33 cases of dyslipidemia. A total of 103 healthy school-age children were selected as control group. All the subjects underwent 24-hour ambulatory electrocardiography. The comparisons of DC, AC, and HRV were made between the obese and control groups, as well as between children with ortholiposis and dyslipidemia in the obese group. The correlations of BMI with DC, AC, and HRV were analyzed in the obese group.

RESULTS

The obese group showed lower DC, standard deviation of normal-to-normal R-R intervals (SDNN), standard deviation of the average normal-to-normal intervals (SDANN), root mean square of successive differences (RMSSD), low-frequency power (LF), and high-frequency power (HF) than the control group. The AC of the obese group was significantly higher than that of the control group (P<0.05). In the obese group, children with dyslipidemia had significantly lower DC, SDNN, SDANN, RMSSD, LF, and HF, but significantly higher AC and BMI, as compared with those with ortholiposis (P<0.01). In the obese group, BMI was negatively correlated with DC, SDNN, SDANN, RMSSD, and HF (P<0.05), but positively correlated with AC (P<0.05).

CONCLUSIONS

Obese school-age children have impaired autonomic nerve function, presenting with reduced vagal tone, which is particularly prominent in those with dyslipidemia. The more obese the children, the lower the vagal tone, which may increase the risks of cardiovascular diseases.

[Changes in ambulatory electrocardiographic findings after oral administration of low-dose propranolol in infants with hemangioma]

OBJECTIVE

To investigate the effects of oral administration of low-dose propranolol on heart rate variability (HRV), acceleration capacity (AC), deceleration capacity (DC), and cardiac conduction in the treatment of infantile hemangioma.

METHODS

A total of 118 infants with hemangioma (≤1 year) were enrolled, and 24-hour ambulatory electrocardiography was performed before oral administration of low-dose propranolol and after one month of administration. The changes in time-domain indices [standard deviation of all normal sinus RR intervals (SDNN), standard deviation of all mean 5-minute RR intervals (SDANN), root mean squared successive difference (RMSSD), and percentage of successive normal sinus RR intervals >50 ms (PNN50)] and frequency-domain indices [low frequency (LF) and high frequency (HF)] for HRV, AC, and DC were observed, as well as abnormalities in cardiac conduction and other aspects after administration of propranolol.

RESULTS

After administration of propranolol, the infants had significantly increased SDNN, RMSSD, LF, HF, and PNN50 (P<0.01), and significantly reduced AC, mean heart rate (HR) and minimum HR (P<0.01). The 24-hour ambulatory electrocardiographic findings showed a nonsignificantly higher abnormal rate after administration of propranolol.

CONCLUSIONS

In the treatment of infantile hemangioma, propranolol can inhibit the activity of sympathetic nerve and block cardiac conduction, but without any serious adverse effect.