Causes & Risk Factors Of Wolff-Parkinson-White Syndrome
Wolff-Parkinson-White syndrome is a condition in which individuals are born with an accessory pathway in their hearts, which can cause many complications. There have been occasional cases of Wolff-Parkinson-White syndrome leading to cardiac arrest, and it can be fatal. Wolff-Parkinson-White syndrome can be somewhat unpredictable, as some who are born with it never experience symptoms while others can become symptomatic at any age. While the true cause of Wolff-Parkinson-White syndrome remains unknown in many cases, there is evidence to suggest, in addition to the extra electrical pathway in heart, there are a few other factors for the condition.
Abnormal Gene
There are seven known mutations in the PRKAG2 gene linked to Wolff-Parkinson-White syndrome. Studies suggest mutations in this gene change the functioning of AMP-activated protein kinase, which thereby alters the enzyme's ability to meet energy demands from cells. Currently, research is not conclusive on whether the enzyme suffers from a decrease in activity or if it becomes over-activated.
What is known about Wolff-Parkinson-White syndrome is, when it is familial, it is autosomally dominant regarding genetic inheritance. This means fifty percent of a person's offspring will inherit this abnormal gene and could potentially develop Wolff-Parkinson-White symptoms. This cause is considered rare, and hypertrophic cardiomyopathy might accompany the abnormality.
Extra Electrical Pathway In The Heart
Patients with Wolff-Parkinson-White syndrome have an extra electrical pathway in their heart, which is known as an accessory pathway, and it lets electrical signals go past the atrioventricular node, causing signals to become disrupted and tachycardia to occur. This can leave an individual feeling like they are short of breath, and they might even experience fainting episodes. While heart palpitations are fairly common and do not typically cause serious harm, arrhythmia associated with them, especially paroxysmal superventricular tachycardia in the case of Wolff-Parkinson-White syndrome, can cause cardiac arrest and are potentially fatal.
Ebstein's Anomaly
Ebstein's anomaly is a congenital heart defect that causes the tricuspid valve, which is located between the right ventricle and right atrium, to malfunction. This anomaly causes the tricuspid to be positioned lower than usual in the right ventricle and for its leaflets to be misshapen, leading to blood leaking back through the valve.
Ebstein's anomaly can also cause heart failure or be responsible for an enlarged heart. While it is not scientifically understood why this defect occurs, it appears in some cases of Wolff-Parkinson-White syndrome as well as in patients with holes in their hearts and those who have arrhythmias. There is some speculation about how pregnant women taking particular medications, such as lithium, could result in the child having Ebstein's.
A Heart Defect
It has been estimated somewhere between seven and twenty percent of patients with Wolff-Parkinson-White syndrome have some other type of heart defect. In fact, roughly fifteen percent of children with Wolff-Parkinson-White syndrome present with another type of congenital heart defect. Scientists are not yet quite sure precisely why this happens, but it is certainly regarded as a risk factor.
One of the most well-documented defects associated with Wolff-Parkinson-White syndrome is familial hypertrophic cardiomyopathy (FHC), which is an autosomal dominant condition that causes ventricular hypertrophy, a thickening of the left ventricle's walls. The reason for this condition is not yet scientifically known.
Gender
Studies are still ongoing to determine how gender plays a role as a risk factor for Wolff-Parkinson-White syndrome. There does seem to be some differentiation between where the accessory pathway is found. One study conducted on 282 participants found more males than females had a left posterior accessory pathway while more females than males presented with a right annular accessory pathway.
More research is necessary to understand why this is the case, but this does suggest a genetic component for Wolff-Parkinson-White syndrome. Additionally, it should be noted men are more at risk for experiencing atrial fibrillation, an irregular heartbeat in the heart's upper atria, especially if they are between the ages of thirty and fifty or have a history of syncope.