Your heart is a finely tuned electrical machine. It is wired perfectly to allow electrical signals to travel through it in a coordinated manner. Those electrical signals are what make our hearts beat, allowing blood to be circulated throughout our bodies to feed our muscles the oxygen they need to power us through life.
Wolff-Parkinson-White Syndrome is a disturbance in the heart’s electrical system. In Wolff-Parkinson-White (WPW) Syndrome, the heart has an extra “wire” (called an accessory pathway) which connects the heart’s lower chambers with the upper chambers through which the electrical signal travels. This extra pathway disrupts the heart’s normal function.
Where does the heart’s electrical signal come from?
The electrical signal starts in a small group of cells called the sinoatrial node (or SA node) located in the heart’s upper right chamber. Charged ions are separated by a cell membrane. This sets up a charge differential (called a membrane potential) between the inside and the outside of the cells within the SA node. The insides of the cells are more negative than their surroundings. In this case, we say that the cells are polarized.
Cells in the SA node automatically open channels in their membranes to allow some ions out of the cell and let others in, which changes the charge of the cell. The cell then becomes more positive. This is called depolarization.
When the electrical signal—the wave of depolarization—travels to surrounding heart muscle cells, it causes the cells to contract. Thus, the squeezing movement of the heart.
The heart is “wired” in such a way that it allows the signal to travel through both upper chambers before pausing for a fraction of a second at another node called the atrioventricular node (or AV node) which is located between the heart’s upper and lower chambers. This pause is important for proper functioning of the heart.
After pausing at the AV node, the signal then travels through the lower two chambers, causing heart muscle cells to contract and push the blood wherever it needs to go in your body.
The cycle then starts all over again with automatic depolarization at the SA node.
Where does the accessory pathway of Wolff-Parkinson-White Syndrome come in?
As stated above, in Wolff-Parkinson-White Syndrome there is an extra “wire” that connects the upper and lower chambers of the heart called an accessory pathway. The electrical signal can travel through this pathway, bypassing the AV node. Recall that the electrical signal pauses for a fraction of a second at the AV node. This allows the lower chambers of the heart to properly fill with blood before sending it out to your body.
In WPW Syndrome the circuit created by the accessory pathway makes the heart beat too fast. This can lead to atrial fibrillation or AV reentrant tachycardia (rapidly beating heart). If the heart beats too fast or if it’s out of synch, it won’t be able to properly do its job.
Symptoms of Wolff-Parkinson-White Syndrome
Wolff-Parkinson-White Syndrome During Pregnancy
Wolff-Parkinson-White Syndrome is usually discovered in childhood or when the patient is in their early 20s. Sometimes previously undiagnosed heart arrhythmias come to light during pregnancy because of the extra burden that is placed on the expectant mother’s body and internal organs. A pregnant woman’s heart is stretched and working harder than normal to accommodate an increase in her blood volume. That extra stress may reveal an arrhythmia.
The mainstay of treatment for symptomatic WPW Syndrome in patients that are not pregnant is catheter ablation. In this procedure, a catheter is threaded through your blood vessels to your heart in order to destroy the accessory pathway, usually via radio frequency, and encourage the growth of scar tissue in that area. However, this procedure involves some radiation which can be harmful to a developing fetus. Your doctor will likely try to control your symptoms with medication that is considered safe in pregnancy. If your symptoms continue despite treatment with medication, catheter ablation can be performed as a last resort.
If you are having symptoms of a heart arrhythmia during your pregnancy, you should consult your doctor right away. The last thing you want is a disruption in your developing baby’s blood supply. With proper management, a woman with Wolff-Parkinson-White Syndrome can have a safe and healthy pregnancy.