ABSTRACT Heart Rate Variability (HRV) is a specific and sensitive noninvasive tool to evaluate cardiac autonomic activity. Our study focuses on using Heart Rate Variability to determine and compare cardiac autonomic status in asymptomatic and symptomatic menopausal women. Methods: Subjects were categorized as asymptomatic menopausal women (n=50) and symptomatic menopausal women (n=50) based on 21 postmenopausal symptoms given in The Greene Climacteric Scale. ECG was recorded in a quiet room with the subject in supine position after 10 minutes of rest. Analog ECG signal was converted to digital by using National Instruments NI-DAQ 7.5 USBD 6008. HRV parameters like SDNN, E: I, LF nu, HF nu, LF/HF was calculated with the help of HRV software (version 1.1). Results: There was a significant (p<0.001) decrease in SDNN, E/I ratio, HF nu and a significant (p<0.001) increase in LF nu, LF/HF in symptomatic women, compared with asymptomatic women. Conclusion: In symptomatic menopausal women our study showed a significant reduction in parasympathetic activity and a significant increase in sympathetic activity. There was a shift in the sympathovagal balance towards sympathetic predominance among symptomatic menopausal women in contrast to asymptomatic menopausal women.

Keywords: Postmenopausal Symptoms, Heart Rate Variability.

 

Introduction:

Menopause starts when menstruation is terminated permanently due to loss of ovarian function1. A woman spends 1/3 of her life in the postmenopausal state. Health management during this period could be considered important because it affects the entire quality of life2. Average age of menopause is 47.5 years in Indian women 3. The menopausal state could be broadly divided into 3 stages: premenopause, perimenopause, and postmenopause. Based on the last menstrual period, if the period of amenorrhea is longer than 12 months, it is considered postmenopause. First 3 months of amenorrhea is considered premenopause. Perimenopause is amenorrhea of 3-12 months, and the volume or frequency of menstruation becomes irregular due to estrogen deficiency during perimenopause. Many women present with diverse physical as well as psychological symptoms during perimenopause and postmenopause. They are referred to as climacteric symptoms or menopausal symptoms4.

Heart Rate Variability (HRV) is a specific and sensitive noninvasive tool to evaluate cardiac autonomic activity. HRV is the degree of variation of the heart rate under the balanced influence of sympathetic and parasympathetic components of the cardiac autonomic nervous system. HRV also indicates the extent of neuronal damage to autonomic nervous system5. Until now, study of the correlation of such menopausal symptoms with heart rate variability has not been adequate. This study is an effort to compare the heart rate variability between asymptomatic and symptomatic menopausal women. In this study, the relationship of menopausal symptoms with heart rate variability was examined using a questionnaire survey method.

 

Methods and Materials:

This study consists of 100 healthy female subjects, 50 of them were asymptomatic menopausal women and the remaining 50 were symptomatic menopausal women .The study subjects were selected from the patient attendants coming to Sri Siddhartha Medical College Hospital, Tumkur. The Greene Climacteric Scale has been used as an evaluation tool for screening of menopausal syndrome. This tool consists of items for total 21 symptoms 6. Data were collected by the subjects who agreed to participate in the study and filled out the questionnaire by themselves. Subject’s clinical history and details were taken according to the standard proforma. Informed written consent was taken from all subjects in the study. Subjects with major illness like diabetes mellitus, hypertension and endocrinal disorders and on any drugs affecting the Autonomic Nervous System like adrenergic blockers, calcium channel blockers, others were also excluded.

 

Measurement of Heart Rate Variability parameters:

Subjects were explained in detail about the ongoing procedure and ECG was digitally recorded after 10 minutes rest using lead II. First, a 5 minutes ECG in supine position was recorded, with subject breathing normally and used to determine the SDNN, LF, HF and LF/HF. Then, the person was periodically instructed to take alternating 5 seconds of deep inspiration and 5 seconds of deep expiration for a period of 2 minutes and simultaneous ECG was recorded. This data was used to measure the E/I ratio.

ECG machine (BPL Cardiart 1087/MK-V) was used to acquire ECG signal. Analog to digital converter (National Instruments NI-DAQ 7.5 USBD 6008) was used as the hardware, to convert the analog signal to digital and processed it to the computer with the help of the NIDAQ software. Heart Rate Variability software (version 1.1), was used in the computer, to detect the peak to peak intervals and further mathematical and analytical calculations in order to get the values of the parameters.

 

Statistical analysis:

Descriptive statistical analysis has been carried out in the present study. Results on continuous measurements are presented on Mean ±SD and results on categorical measurements are presented in Number (%). Significance is assessed at 5 % level of significance. Student‘t’ test (two tailed, independent) has been used to find the significance of study parameters on continuous scale between two groups Inter group analysis.

 

Results:

The comparison of the basic characteristics like age, BMI, duration of amenorrhea, systolic blood pressure and the diastolic blood pressure between the two groups did not show significant difference (p>0.05). The two groups were similar in terms of the baseline characteristics [Table-1].

There was a significant (p<0.001) decrease in SDNN, E/I ratio, HF normalized units (nu) [Table2, 3] and a significant (p<0.001) increase in LF nu, LF/HF in symptomatic women [Table 3], compared with asymptomatic women.

 

 

 

 

 

 

 

Table 1: Baseline characteristics of subjects.

Characteristics Symptomatic women

(n = 50)

Asymptomatic women  (n = 50) P-value*
Age (y) 50.7 ± 1.9 49.8 ± 2.1 0.523
BMI (kg/m2) 22.75±1.73 23.19±1.31 0.157
Duration of amenorrhea (mo) 20.10 ± 4.17 18.30± 3.21 0.482
Systolic blood pressure (mm Hg) 118.2 ± 6.9 118.7 ± 10.6 0.284
Diastolic blood pressure (mm Hg) 78.5 ± 6.6 74.8 ± 5.6 0.150

 

Table 2:  Comparison of Time domain parameters between cases and controls.

HRV Symptomatic women Asymptomatic women p value
SDNN(ms) 34.22±14.00 69.10±26.09 <0.001**
E/I ratio 1.37±0.14 1.76±0.46 <0.001**

 

Table 3: Comparison of Frequency domain parameters between cases and controls.

HRV Symptomatic women Asymptomatic women p value
LF nu 61.52±14.62 36.11±11.68 <0.001**
HF nu 38.49±14.64 63.70±11.97 <0.001**
LF/HF 2.10±1.54 0.63±0.36 <0.001**

Discussion:

Heart Rate Variability is a specific and sensitive noninvasive tool to evaluate cardiac autonomic activity.  HRV is the degree of variation of the heart rate during the day under the balanced influence of sympathetic and parasympathetic component of the cardiac autonomic nervous system7. Until now, study of the correlation of such menopausal symptoms with heart rate variability has not been adequate. The basic cause of menopausal symptoms is the complex relationship of estrogen metabolism and the autonomic nervous system. Therefore, imbalance of the autonomic nervous system may correlate with menopausal symptoms. Disharmony of the autonomic nervous system could be evaluated by measurement of heart rate variability (HRV) 8.

The LF nu values are considered as a measure of sympathetic activity 9-12. In this study the LF nu values were significantly increased in symptomatic menopausal women (p<0.001), thus suggesting the presence of elevated cardiac sympathetic activity in them.

The HF nu values are considered as a measure of parasympathetic activity9-12. In this study the HF nu values were significantly reduced in symptomatic menopausal women (p<0.001) which further adds on to the earlier finding of decreased cardiac parasympathetic activity.

 

The LF/HF values reveal the global sympathovagal balance9-12. In  this  study  the LF/HF  values  were  significantly  higher  in symptomatic menopausal women  when  compared  to asymptomatic menopausal women (p<0.001)  thus  suggesting  the  alteration  in  the  sympathovagal  balance  towards  the  sympathetic  component  in symptomatic menopausal women.

the SDNN values reveal the alterations in the autonomic tone that are predominantly vaglly mediated. In this study SDNN values were siginificantly reduced in symptomatic menopausal women(p<0.001). Thus the suggesting the reduction in the parasympathetic activity.

Summary and Conclusions:

The present study showed that among the subjects studied there was altered cardiac autonomic activity in symptomatic menopausal women. Symptomatic menopausal women showed a significant reduction of parasympathetic activity and a significant increase in sympathetic activity. There was a shift in the sympathovagal balance towards sympathetic predominance among symptomatic menopausal women in contrast to asymptomatic menopausal women.

 

References:

1. Speroff L, Glass RH, Kase NG. Clinical gynecologic endocrinology and infertility. 5th ed. Baltimore: Williams & Wilkins; 1994.

2. Kim MJ, Kim JH. How long do menopausal hot flushes really last? J Korean Soc Menopause 2009;15:73-8.

3. Unni J. Third consensus meeting of Indian Menopause Society (2008): A summary. J Mid-life Health 2010;1:43-7.

4. McKinlay SM, Brambilla DJ, Posner JG. The normal menopause transition. Maturitas 1992;14:103-15.

5. Heart rate variability: standards of measurement, physiological interpretation and clinical use. Task force of the European society of cardiology and the North American society of pacing and electrophysiology.European Heart Journal 1996;17:354-81.

6. Greene JG. A factor analytic study of climacteric symptoms. J Psychosom Res 1976; 20:425-30.

7. Sztajzel J. Heart rate variability: a noninvasive electrocardiographic method to measure the autonomic nervous system. Swiss Med Wkly 2004;134:514-22.

8. Earnest CP, Lavie CJ, Blair SN, Church TS. Heart rate variability characteristics in sedentary postmenopausal women following six months of exercise training: the DREW study. PLoS One 2008;3:e2288.

9. Heart rate variability: standards of measurement, physiological interpretation and clinical use. Task force of the European society of cardiology and the North American society of pacing and electrophysiology. European Heart Journal 1996;17:354-81.

10. Sztajzel J. Heart rate variability: a noninvasive electrocardiographic method to measure the autonomic nervous system. Swiss Med Wkly 2004;134:514-22.

11. Low PA. Clinical autonomic disorders:Analysis of blood pressure and heart rate variability. 2nd ed. Philadelphia: Lippincott-Raven Publishers; 1997. 309-20.

12. Katira T, Narain VS, Puri VK. Heart rate variability. JAPI 1997;45(1):49-51.

 

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