ECG and the heart

The heart does not belong to gynaecology – and yet it comes up regularly at this practice. In pregnancy it does forty per cent more work than usual, in the menopause the risk profile changes fundamentally, and the question of oestrogen-containing contraception is always also a question about the blood vessels. This page explains what an ECG shows, when it makes sense in women and what is normal in pregnancy.

What an ECG measures

Every heartbeat begins with an electrical impulse that spreads across the heart muscle and makes it contract. These currents can be measured at the surface of the body. Electrodes on the arms, legs and chest record the change in voltage – the result is the familiar tracing.

A standard ECG has twelve leads, that is twelve viewpoints on the same event. From them, rhythm, rate, the position of the heart, disturbances of conduction and signs of impaired blood supply can be read.

The examination takes a few minutes, does not hurt and gives off no energy – it only measures, it transmits nothing. Neither radiation nor current enters the body. That is why an ECG is possible without restriction in pregnancy and harmless at any point, even repeatedly.

What the heart does in pregnancy

The changes are considerable, and they are the reason why many symptoms in pregnancy sound like the heart without anything being wrong.

The heart beats faster and pumps more with each beat. At the same time the vessels widen, so that blood pressure tends to fall in the middle third – hence the dizziness on standing up that many women know from around the twelfth to twentieth week.

In the ECG of a pregnant woman there are therefore routinely changes that would be abnormal outside pregnancy: a slightly raised rate, a shift of the cardiac axis to the left because the diaphragm is pushed up, and occasionally small changes in repolarisation. Anyone reading the ECG of a pregnant woman without knowing this easily finds something that is not there.

Palpitations in pregnancy

This is the commonest question on the subject. Extra beats – single beats that come too early and leave a short pause after them – occur more often in pregnancy than otherwise. They are felt as a stumble, a skipped beat or a brief thud in the throat, and in women with healthy hearts they are of no significance.

A racing heart also occurs, particularly in the third trimester and on standing up. Usually it is a simple adaptation: more volume, less room, a higher baseline pulse. It is made worse by caffeine, too little sleep and nervousness – three circumstances that are rarely all absent in a pregnancy.

It still needs investigating if one of these is present as well:

• a racing heart with a sudden start and a sudden end
• loss of consciousness or nearly fainting
• breathlessness at rest or when lying flat
• chest pain
• a known heart condition or a heart defect in the family

An ECG is then the first step, often supplemented by a 24-hour recording, because a single strip only catches the disturbance by chance. Where there is corresponding suspicion, an ultrasound of the heart follows – that too is harmless in pregnancy.

One clue that is often overlooked: marked iron deficiency causes palpitations, breathlessness and exhaustion that cannot be distinguished from the picture of heart disease. A blood count with ferritin therefore belongs to the assessment and is more often the answer than the ECG.

Contraception and the cardiovascular system

Here gynaecology has its own, well-founded responsibility. Oestrogen-containing contraceptives – the combined pill, the vaginal ring and the patch – raise the risk of thrombosis. The absolute risk is small, but it rises markedly when other factors are added.

That is why, before every prescription, questions are asked: about thromboses in you or in your family, about smoking, about migraine with aura, about high blood pressure, about weight and about long periods of immobility. Blood pressure is measured. An ECG is not routinely needed for this, but it is where there are known rhythm disturbances or heart disease.

Three constellations rule out oestrogen-containing contraception: smoking from the age of 35, migraine with aura at any age, and a previous thrombosis or pulmonary embolism. In all these cases oestrogen-free options remain open – the progestogen-only pill, the implant, the hormonal coil and the hormone-free methods. All of them appear with their figures in the contraception comparison, and the hormonal coil in detail on its own page.

High blood pressure in pregnancy

Blood pressure is measured at every examination in the Eltern-Kind-Pass, and there is a precise reason for that: it is the earliest and most reliable sign of pre-eclampsia.

High blood pressure is defined from values of 140 over 90. What matters is when it appears. Hypertension that existed before the pregnancy or is found before the 20th week is a condition in its own right and is treated as such. If it appears newly after the 20th week, the pregnancy is the cause – and then a closer look is taken.

If protein in the urine or involvement of other organs is added to the new hypertension, it is called pre-eclampsia. It affects about two to five in a hundred pregnancies and is the most important cause of danger to mother and baby in the final third. The most severe form, HELLP syndrome, shows itself with upper abdominal pain, raised liver values and falling platelets.

Warning signs that need investigating the same day: severe headache, flickering or flashes of light before the eyes, pain in the right upper abdomen, sudden swelling of hands and face, rapid weight gain over a few days. Whether the weight is within the expected range is shown by the weight calculator – a sudden gain of several kilos in a week is something different from a steady rise.

Prevention is possible where the risk is raised: low-dose aspirin, started before the 16th week and taken into the 36th, markedly reduces the frequency of early pre-eclampsia. Who benefits follows from the history – previous pre-eclampsia, high blood pressure, diabetes, kidney disease, autoimmune disease, multiple pregnancy – and is discussed at the first appointment.

Thrombosis in pregnancy

Pregnancy raises the risk of thrombosis about fivefold, and considerably more again after the birth. Three circumstances come together: clotting is altered – a sensible preparation for the birth – the growing uterus impedes the return of blood from the legs, and movement decreases towards the end.

A deep vein thrombosis usually shows itself on one side: swelling, a feeling of tightness, warmth, pain in the calf or thigh. The left side is affected more often. A pulmonary embolism announces itself with sudden breathlessness, chest pain on breathing, coughing or a racing heart – here call 144 immediately.

Important for judging this: swollen legs are normal in late pregnancy if they occur on both sides and increase towards evening. It becomes abnormal with swelling on one side. That is the most practically useful distinction.

Prevention consists of movement, drinking enough and compression stockings, which are inelegant and effective. Where the risk is raised – previous thrombosis, known clotting disorder, caesarean section, longer immobility – low molecular weight heparin is given; it does not cross to the baby and can be used in pregnancy and while breastfeeding.

The heart in the menopause

Before the menopause, women have heart attacks considerably less often than men of the same age. After the menopause that equalises. The loss of oestrogen changes blood lipids unfavourably, the vessels become stiffer, blood pressure rises.

This is not a side issue: cardiovascular disease is the commonest cause of death in women in Austria – more common than all cancers together and many times more common than breast cancer. In public perception it is the other way round.

From this stage of life, blood pressure, blood lipids and blood sugar therefore need checking regularly – through the general health check, which in Austria is available annually through the e-card at a GP practice. The screening planner shows what is provided for at which age.

For hormone replacement therapy there is a window in time: if it is started in the first ten years after the menopause and before the age of 60, the balance for the cardiovascular system is favourable or at least neutral. A late start with vessels already altered is judged differently. Before deciding, blood pressure, blood lipids and the personal history are established – the menopause score sorts the symptoms first.

When women have a heart attack

This section belongs on a gynaecology page because that is where it is most likely to be read. In a heart attack, women more often than men have symptoms that do not match the familiar picture.

Instead of the typical chest pain radiating into the left arm, there may be: nausea and vomiting, pain in the upper abdomen, back or jaw pain, breathlessness, unusual exhaustion, cold sweat, anxiety. These symptoms are more often interpreted by the women themselves as an upset stomach or exhaustion – and by those treating them as well.

The consequence is measurable: women arrive at hospital later on average, and the time to treatment decides how much damage remains. Hence the clear rule: with unusual, persistent symptoms in the chest or upper abdomen together with breathlessness, weakness or cold sweat, call 144 – do not wait, do not drive yourself, and rather once too often.

When heart disease is already known

More and more women with congenital heart defects reach adulthood thanks to paediatric cardiology, and become pregnant. For them a simple but consequential rule applies: the counselling belongs before the pregnancy, not within it.

The reason lies in the changes described above. A heart that copes in everyday life can reach its limit with forty per cent more volume – and the steepest rise comes not at the birth but immediately afterwards, when the uterus contracts and its blood flows back into the circulation. Medication also has to be reviewed: some common heart medicines, among them ACE inhibitors and sartans, cannot be used in pregnancy and are changed beforehand.

Care is then shared with a cardiologist and, depending on the starting position, at a centre with the corresponding experience. What this practice provides is the gynaecological care and the timely setting of the course – not the cardiological management.

The same applies to contraception with known heart disease: it is particularly important there, because an unplanned pregnancy means a real risk, and at the same time the choice is restricted. Oestrogen-free methods with high reliability – the hormonal coil, the implant – are usually the first choice here.

When an ECG is done in gynaecology

• with palpitations, a racing heart or dizziness where a rhythm disturbance is suspected
• with fainting or nearly fainting
• with chest pain or breathlessness not explained by the pregnancy
• before major procedures, where a pre-existing condition or age suggests it
• with known heart disease as part of antenatal care, in agreement with cardiology
• with high blood pressure in pregnancy, as part of the assessment

What makes no sense is an ECG as a screening test in healthy young women without symptoms. It rarely finds anything significant there and frequently finds trivia that lead to further investigations without anything having been wrong in the end. This chain of incidental finding, check, doubt and further investigation costs weeks of worry and changes nothing – a good reason to tie every examination to a question rather than doing it just in case.

How an ECG is done

No preparation is needed, and you do not have to be fasting. The upper body is uncovered, four electrodes are attached at the wrists and ankles and six more on the chest in a defined arrangement. Contact gel or adhesive electrodes provide the connection.

The recording itself takes about ten seconds. What matters is to lie still during that time, breathe calmly and not speak: muscle tension overlays the cardiac currents and makes the tracing unusable. Feeling cold is the commonest reason for an unusable ECG – shivering produces exactly the interference that cannot be worked with.

In late pregnancy the recording is not taken flat on the back but lying slightly on the left side. The reason is the same as with sleeping: flat on the back, the uterus presses on the inferior vena cava, the return to the heart falls, and you can feel unwell. That is not a peculiarity of the ECG but a general rule for any longer period on your back in the final third.

What an ECG does not show

A resting ECG is a snapshot of a few seconds. A rhythm disturbance that occurs twice a week is very unlikely to be seen in it. A normal ECG therefore rules out neither a rhythm disturbance nor impaired blood supply.

For the rhythm question there is the 24-hour recording or longer, for the blood supply question the exercise ECG and further methods. And no ECG shows the pumping function, the valves and the wall thickness – that is what an ultrasound of the heart is for.

At this practice an ECG is therefore used where it answers a concrete question – and otherwise referral to cardiology follows. A finding that cannot be interpreted helps nobody.

Where to go from here

If you notice palpitations, a racing heart or breathlessness, it needs discussing – in pregnancy as much as outside it. Often the cause is harmless or lies with iron; sometimes not, and then what counts is that it is noticed early. Make an appointment. In an acute emergency in Austria, call the ambulance on 144.