Wolff-Parkinson-White syndrome


The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.

What is Wolff-Parkinson-White syndrome?

Wolff-Parkinson-White (WPW) syndrome is a condition in which there is a congenital abnormality of the electrical conduction system of the heart, characterized particularly by the presence of an accessory pathway. This is a system or bundle of specialized muscle cells that carry electrical impulses from the bottom of the ventricles (the hearts lower chambers) upward into the atria (the hearts upper chambers), causing a concentration of muscle fibers, called the atrioventricular (AV) node, to be stimulated prematurely.

Normally, the hearts natural pacemaker called the sinoatrial (SA) node, located near the very top part of the right atrium sends out an electrical impulse that makes the two atria contract, and also reaches the AV node, which then relays the signal to tell the two ventricles to contract, just after the atria are finishing contracting. In a heart with WPW, the signal returning through the extra pathway from the ventricles competes with the SA node, causing episodes of tachycardia (rapid heartbeat).

In many people with WPW, there are no symptoms, but symptoms can come on abruptly and pregnancy can make a woman prone to this happening if she was born with an accessory pathway. WPW is a particular category of a broader set of conditions called supraventricular tachyarrhythmia (SVT) conditions because the problem is coming from above the ventricles, meaning early stimulation of the AV node, even though the extra signal begins in the ventricles.

How common is WPW during pregnancy?

SVT itself is present in about 24 per 100,000 patients who are admitted to the hospital and can be exacerbated by pregnancy. WPW is fairly common during pregnancy, as it is one of the most typical reasons for SVT in young women.

How is WPW diagnosed?

WPW is diagnosed by way of electrocardiography (ECG, sometimes abbreviated EKG), and also through Holter monitoring. Both are non-invasive procedures that work through electrodes that are attached to your skin. In ECG, electrodes are attached on your arms, leg, and chest, and in some cases, additional sites, to provide your family doctor, obstetrician, and cardiologist with detailed information of the hearts electrical activity from numerous angles in order to detect problems in different regions of the heart. This can be done in the doctors office or the hospital. With Holter monitoring, the principle is the same as ECG, but you are fitted with a device that you wear for a day or more while you go about your normal activities. Various types of Holter monitors are available with varying numbers of electrodes, depending on how much detail is needed about different parts of your heart. In all cases, however, unlike ECG, the Holter monitor records data constantly and transmits those data to your doctor (or the data are downloaded when you return to the doctor). Consequently, if an event called reentry (movement of electrical signals upward from the ventricles to the atria) happens just once in a while, your doctors can see it.

Does WPW cause problems during pregnancy?

A potential consequence of a WPW episode is what doctors call hemodynamic instability, meaning that the cardiovascular system is unstable and potentially can collapse, leading to a substantial drop in blood pressure, which could lead you to pass out.

Does WPW during pregnancy cause problems for the baby?

An SVT episode due to a WPW pathway that destabilizes your cardiovascular system can put the health and life of the developing baby at risk by causing a reduction of blood circulation through the uterus and placenta.

What to consider about taking medications when you are pregnant or breastfeeding:

  • The risks to yourself and your baby if you do not treat the WPW.
  • The risks and benefits of each medication you use when you are pregnant
  • The risks and benefits of each medication you use when you are breastfeeding

What should I know about using medication to treat my WPW during pregnancy?

The first choice medication to treat an episode of SVT resulting from WPW is called adenosine, which is given intravenously to calm down the heart. This drug disappears from the mothers bloodstream in a matter of seconds, so it has virtually no effect on the developing baby and thus is considered extremely safe in pregnancy. There is controversy surrounding which medications are best for treating WPW in the long-term. A group of medications called beta-blockers examples are propranolol, metoprolol, and labetalol are used in certain cases and may be modestly effective, and are considered relatively safe during pregnancy. Stronger anti-arrhythmia medications include flecainide, propafenone, sotalol, and amiodarone have been shown to be more effective in inhibiting accessory electrical pathways present in WPW, but data showing the safety of these drugs during pregnancy are very limited, plus it is difficult to maintain adequate levels of these drugs in a mothers blood, because of changes in blood volume during pregnancy, so these are not the first choice for WPW in pregnant women.

Who should NOT stop taking medication for WPW during pregnancy?

Any pregnant woman who experiences an SVT attack due to WPW should receive adenosine, or another drug to stop the attack, due to the risk of cardiovascular collapse.

What should I know about choosing a medication for my WPW during pregnancy?

You may find Pregistrys expert reports about the individual medications used to treat WPW here. Additional information can also be found in the sources listed at the end of this report.

What should I know about taking a medication for my WPW when I am breastfeeding?

Propranolol, metoprolol, and labetalol are considered safe during breastfeeding as there is minimal absorption into the breastmilk. Adenosine given to a mother is not dangerous to the nursing infant since it disappears very rapidly from the mothers blood.

What alternative therapies besides medications can I use to treat my WPW during pregnancy?

WPW is treated effectively with a technique called ablation, in which a specially-trained cardiologist guides instruments through tubes through your blood vessels to the heart and destroys the accessory conduction pathway. This procedure can be done safely during pregnancy, and is the treatment of choice, as it is generally more effective than medications, and once it is completed the patient is permanently cured.

A short-term treatment that often can end an SVT episode in an emergency is vagus nerve stimulation. This can be achieved by massaging the carotid area of the neck, or by dipping the womans head partly in cold water. In the event that you have an SVT episode that cannot be stabilized, a cesarean section may become necessary.

What can I do for myself and my baby when I have WPW during pregnancy?

Cooperate with your physicians. If medications are recommended to stabilize your condition, keep in mind that this is generally safe, but also consider an ablation treatment.

Resources for WPW in pregnancy:

For more information about WPW during and after pregnancy, contact http://www.womenshealth.gov/ (800-994-9662 [TDD: 888-220-5
446]) or check the following links:


Read the whole report
General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.

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