Introduction
In female reproductive system the cyclical changes occurs and menstruation is periodic bleeding due to shedding of uterine mucosa and there is effect on the ECG changes and blood pressure changes in different phases of menstrual period. So many physical, psychological and behavioral changes are related to menstrual cycle due to changes in ovarian hormones and menstruation is only one manifestation of the ovarian hormones. Alteration in the release of female steroid hormones like progesterone and estrogen in a systematic manner is due to periodic ovarian variation.1 Menstrual cycle normally repeats in every 21–35 days (approximately 28 days). Menstrual cycle can be divided into four different phases, which is based on ovulation time i.e. (a) menstrual phase, (b) follicular phase, (c) ovulatory phase, and (d) luteal phase.
The normal physiological, psychological, and behavioral outcome of the a female body is influenced by changes during menstrual cycle. There is affect on the electrophysiology of the cardiovascular system in humans due to variations in hormone during different phases of menstrual cycle. The hormonal fluctuation during menstrual cycle could stimulate the ion channels result in to affecting the electrophysiological characteristics of the heart. Reproductively active women have different levels of steroid hormone than postmenopausal women and this difference is related to an increase in the incidence of many cardiovascular diseases like sudden cardiac death in postmenopausal women.2 The cardiovascular system is influenced by gonadal hormones directly as well as indirectly. In women suggesting possible sex differences in atrial and AV nodal physiology and this is been suggested due to PR intervals are shorter in females. 3 During the luteal phase of the menstrual cycle, pregnancy, and the perimenopausal period palpitations occur frequently in women at all ages. The increased sympathetic activity may be related to palpitation during the perimenopausal period. 4 Due to the variation in the hormonal flux occurrence of several cardiac diseases varies throughout the menstrual cycle. The occurrence of ventricular tachycardia, Torsade de Pointes (TdP) increase in the reproductively active women.5 Throughout the menstrual cycle in reproductive women there is cyclic variation of sex hormones occurs and this variation results in to physiological alteration of cardiovascular activities which ultimately affects Electrocardiogram (ECG) parameters.6 Progesterone shortens the duration of action potential and QT interval duration in the woman due to effect on ventricular repolarization. In a single menstrual cycle it is the progesterone level which affects electrophysiology of than estrogen. 7 The time from the beginning of atrial depolarization to the onset of ventricular depolarization denotes the PR interval which is measured from the surface electrocardiogram (ECG). Prolonged PR interval is significantly associated with the risk of cardiovascular mortality and sudden cardiac death (SCD). 8
The delay in conduction at AV node influences the PR interval and change in conduction velocity in bundle of His and Purkinje fibers is denoted by change in width of QRS complex. The QT interval represents the time during which the ventricles are depolarized and thus reflects the duration of the ventricular action potential. Any change in the processes occur during ventricular repolarization is represented by change in QT Interval. 9
Aim
The aim of this study is to analyze the heart rate, the changes in PR interval and duration of ST segment in ECG in reproductive women during menstrual phases.
Objectives
To investigate any change in heart rate, PR interval and duration of ST segment in ECG during different phases of menstrual cycle using Electrocardiograph in females having normal menstrual cycle.
Materials and Methods
Place of study
Central research laboratory situated in the department of Physiology at Bundelkhand medical college, Sagar, M.P.
Method
Approval from institutional ethical committee has been taken and the participants were enrolled for the study after fulfilling exclusion and inclusion criteria. After explaining the study methodology informed consents were taken from the participants. They were instructed not to smoke or consume alcohol, caffeine or to engage in strenuous physical activity 12 hours prior to testing. They were called according to the day of menstrual cycle. Participants were taken a thorough history and general examination prior to recording of ECG. The resting ECG was recorded to a segment length of 10 seconds, at a paper speed of 25 mm per second by using Bene Heart R3 Electrocardiograph by mindray. Participant’s ECGs was examined for PR interval and duration of ST segment. Heart rate was calculated using R-R interval in lead II.
According to the phases of menstrual cycle candidates have undergone the recording of ECG which was done on:
Menstrual phase (MP - (2nd day)
Proliferative phase (PP - (11th day)
Secretory phase (SP - (22nd day)
Statistical analysis was done by using statistical online calculator statskingdom.com for paired t-test and Microsoft excel to calculate mean value. The p-value of 0.05 considered statistically significant.
Observation and Result
Table 1
|
Average age of participants (years) |
Average weight of participants (Kilogram) |
Average height of participants (CM) |
Average duration of Menstrual cycle (Days) |
|
21.6 |
47.7 |
149.0667 |
3-4/26-30 |
Table 2
Different parameters – (Average value of each parameter)
Statistical analysis
Table 3
Menstrual phase Vs Proliferative phase
|
S.No |
Parameters |
p-value |
Statistical significance |
|
1 |
Heart rate |
0.002877 |
Highly significant |
|
2 |
PR interval |
0.1223 |
Not significant |
|
3 |
ST segment |
0.02572 |
Significant |
Discussion
In all reproductively active females cyclical changes in female reproductive system occur due to changes in level of female sex steroids and due to these hormonal changes there are periodic histochemical alterations. In present study the change in heart rate starts in proliferative phase which is the phase of high estrogen as compared to progesterone level. During secretory phase the sex steroids estrogen and progesterone are in action and heart rate increases more which is statistically significant in this study. Study done by Ezequias RP et al supports that there is an increased sympathetic and decreased parasympathetic balance in the luteal phase when compared to the follicular phase. 10
Increase in heart rate during luteal phase is more as compared to follicular phase supporting the increase sympathetic action of the body which is due to probably more progesterone level during luteal phase.
PR interval is the time from atrial depolarization to starting of ventricular depolarization. Average time of PR interval is reduced in proliferative phase but it is not statistically significant in present study. Statistically significant reduction in duration of PR interval is seen during secretory phase. The result is same as study done by Shahina Khan et al shows that there is statistical difference in PR interval between menstrual and secreotory phase. 1 During luteal phase which corresponds to secretory phase of uterine cycle sympathetic balance is increased 10 and this supports the finding of the study.
In an electrocardiogram (ECG) between ventricular depolarization (QRS complex) and repolarization (T wave) the ST segment normally represents an electrically neutral area of the complex and this ST segment encompasses the region between the end of ventricular depolarization and beginning of ventricular repolarization.Indication of benign or clinically significant injury or insult to the myocardium may show various waveform morphologies of ST segment.11 Present study there is decrease in duration of ST segment starts in secretory phase and further decreased in proliferative phase showing statistically highly significant during secretory phase. In prior studies it has been shown that there is decrease in QTc interval during secretory phase of menstrual cycle. 1, 5, 7, 9
Conclusion
Due to cyclical fluctuation of hormones during different phases of menstrual cycle alterations in several electrophysiological parameters occurs and it affects the cardiovascular system which is evident in the present study. Sex steroids during different phases certainly show effect on the cardiovascular function indicators. Further study to done with females using Oral Contraceptive pills as contraceptive method as well as for treatment of PCOS.
