European Journal of Cardiovascular Medicine

Females have higher age-standardized rates of acute conditions, chronic conditions, and disability due to acute conditions, compared to males according to National Health Interview Survey for 1957-72.¹ Excess female morbidity is primarily due to various social and psychological factors. Menstrual dysfunction, like other aspects of sexual and reproductive health, is not included in the Global Burden of Disease estimates ^2,3 and, even as reproductive health programs expand their focus to address gynaecologic morbidity, the utility of evaluating and treating menstrual problems is not generally considered. Available data from developing countries on the frequency of menstrual disorders and their impact on women's health status, quality of life and social integration suggest that evaluation and treatment of menstrual complaints should be given a higher priority in primary care programs.⁴

The menstrual cycle is not only just a reproductive event but also has an effect on the general health and well-being of a female. It is characterized by cyclical fluctuations in the levels of FSH, LH, Oestrogen and Progesterone. These hormonal changes also have an effect on Electrocardiographic changes and thus indicate the status of heart. Apart from it being physiological there are various disorders associated with menstrual cycle which has been enculcated in morbidity & mortality among females.

The cyclical changes in hormones are known to have an effect on serum electrolytes which may be responsible for Electrocardiographic changes. Electrocardiographic pattern could be affected by the action of hormones and electrolytes on cardiac repolarisation. Experimental data in animals show that oestradiol regulate the repolarization phase of the cardiac action potential reflected by the QT interval^5,6 and progesterone regulate cardiac repolarisation through a non-genomic pathway. Variations in the oestrogen and progesterone level in the blood during menstrual cycle could affect the electrolyte composition, blood volume, cardiac activity and may also affect the electrocardiographic pattern. Numerous scientific studies have been undertaken on ECG changes during menstrual cycle but the results are often contradictory & variable. So, the present study was undertaken to re-examine the findings and thus provide a screening tool to avoid morbidity and mortality related to menstrual cycle and the result obtained may have significance in terms of normal reference interval. 

The study protocol was approved by the institutional ethical committee in Mahadevappa Rampure Medical College, Gulbarga. The present study was carried out on one hundred (n=100) apparently healthy female medical students of MRMC, Gulbarga in the age group of 18 to 23years with normal regular menstrual cycle of 27-33 days after obtaining the informed and written consent. The present study included only the females having ovulatory cycles which was confirmed by daily recording of Basal Body Temperature (BBT) using thermometer. Subjects below 18yrs and above 23yrs of age, Subjects with endocrinal, cardiovascular & gynecological disorders like diabetes, hypertension, polycystic ovarian disease etc were excluded. Subjects with history of smoking and alcoholism, pregnancy, irregular menstrual cycle were excluded. Subjects taking drugs which affect menstrual cycle like oral contraceptive pills, hormonal replacement therapy and drugs that alter the cardiovascular functions and subjects performing regular exercise were excluded.

Subjects were allowed to rest and relax for half an hour before taking the readings.

Heart rate,PR interval, QT interval was studied on 2^nd ,11^th, 22^nd day of menstrual cycle i.e Menstrual phase, Proliferative phase and Secretory phase of menstrual cycle respectively using AD INSTRUMENT-POWERLAB ® /30 SERIES.

Statistical Analysis: Data was expressed as Mean ± S.D. and was analysed for statistical analysis using SPSS 17.0 Software. To compare means of two independent groups, student’s t- test was used.

Table 1: Electrocardiographic Pattern

*P<0.05- Significant

MP, Menstrual Phase; PP, Proliferative Phase; SP, Secretory Phase

According to table 1 and figures 21,22,23 the Heart rate was significantly (P<0.05) increased in proliferative phase compared to menstrual phase. PR Interval & QT interval showed no significant changes during various phases of menstrual cycle.

Figure 1: Electrocardiographic Pattern: Heart Rate (BPM)

Figure 2: Electrocardiographic pattern: PR interval (sec)

Figure 3: Electro cardiographic pattern: OT interval (sec)

In the present study Heart Rate (BPM) was significantly increased in PP compared to MP (P<0.05). Changes in the level of ions i.e sodium, calcium and potassium due to oestrogen must be increasing electrical excitability in cardiac tissue which led to high heart rate in PP. Study further confirms that these changes are not Autonomic Nervous System dependent, at least in our study as PR interval and QT interval showed no variation. Hence the present changes are dominated by endocrine rather than Autonomic Nervous System. Other study demonstrated significant decrease in heart rate during secretory phase.^7,8Heart rate did not show significant change during different phases of menstrual cycle.^9,10 Some study demonstrated significant increase in heart rate during secretory phase.^10-13Other study indicated decreased parasympathetic activity in luteal phase in healthy young women and Resting heart rate significantly increased in late luteal phase.¹⁴In most studies, the disparate findings might be attributable to methodological limitations, primarily small samples, short ECG recording periods, and single ECG recordings during each phase of the menstrual cycle.

Conclusion: In the present study ECG changes may be attributed to blood volume changes due to electrolytes and hormonal changes. Further studies have to be conducted with large sample size along with serum electrolytes estimation and hormonal assay.

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