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PALPITATIONS AND THE HEART'S ELECTRICAL SYSTEM

Over the last decade, everyone's awareness about women and heart disease has increased. So now, women know that they too are at risk for heart attack.

What is often less appreciated is that women have some important differences in the heart's electrical system and, therefore, often present symptoms differently and respond to tests differently than men do. This normal variation is an important piece of information in women's routine care as well as understanding a common complaint, palpitations.

Woman may have higher heart rates than men and may often exhibit abnormal heart rhythms. The heartbeat is regulated by the autonomic nervous system (the one that controls automatic functions like heart rate, breathing rate, digestion, etc.).

This leads to higher resting heart rates and sometimes abnormally rapid heart rates (tachycardias) as well as passing out due to slow heart beat and low blood pressure (syncope). Women also have more accessory electrical pathways through which signals can travel, another reason that abnormal rapid rhythms (arrhythmias) are seen in women.

Women may also exhibit different EKG norms. Their heart's electrical system has a different structure that allows the heart to take more time in recovering after an electrical signal has passed through. This is seen on the EKG as a longer QT interval, again a known normal variation.

This is important because medications can further prolong this interval and precipitate a very problematic arrhythmia called Torsade des Pointes. Although the QT interval remains the same during the menstrual cycle, the sensitivity to these drugs varies with time in the cycle. Sometimes these extra long QT Syndromes are born into families, particularly in girls who are at risk for this arrhythmia after delivery when estrogen levels are dropping.

Other arrhythmias vary with the menstrual cycle and are often experienced premenstrually. Women who have accessory electrical pathways also may have problems during pregnancy.

The bottom line is that any woman experiencing palpitations should have it seriously evaluated and not written off as anxiety. Although EKGs may be misleading in terms of predicting heart attacks they may in fact be helpful in identifying women with electrical system variation that may be normal but needs to be known about. Other tests like cardiac event monitors, which can document what type of abnormal heart rhythm is occurring at the time you are feeling them can be very helpful.

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