SVT (Supraventricular Tachycardia) in Young Patients
It is rare for young people experience cardiac arrhythmias, but it does occur. Many times it comes about in their late teens or twenties when they are most active with sports, activities, etc. This is the issue that young athlete Rhett Lindholm had.
There are two main types tachyarrythmias found in young people: AV Nodal Re-entrant Tachycardia (AVNRT) and Wolff-Parkinson-White (WPW).
AV Nodal Re-entrant Tachycardia
In cardiac conduction system, the AV node is the gateway, the traffic cop, in the electrical pathway between the atria and ventricles. It controls what signals get through and how fast. In AVNRT, an extra electrical pathway forms and allows an electrical signal to travel backwards through the AV node at the same time. This causes another heartbeat. The two pathways create a continuous electrical signal in a circular pattern called “re-entry”. The extra pathway that forms comes from tissue that behaves very much like the AV node. It is geographically located in the right atrium close to the AV node.
This arrhythmia can cause heart rates 160-220 beats per minute. AVNRT is most common in women. In fact, 75% of the AVNRT cases occur in females. It also is most common in the 20’s and 30’s. Symptoms of AVNRT include syncope or near syncope, faint feeling, lightheadedness, and palpitations.
AVNRT appears on the EKG as a narrow QRS complex tachycardia. The retrograde (re-entry) conduction occurs at the same time as the ventricles beat. Therefore, its P wave will often be hidden by the QRS complex.
Treatments for AV Nodal Re-entrant Tachycardia usually focus on any action that can transiently block the AV node like vagus nerve stimulation techniques including carotid sinus massage and valsalva maneuver. Medications like adenosine, B- blockers, and Ca-channel blockers and procedures like electrical cardioversion and ablation are also sometimes used.
Unlike AVNRT where the extra electrical pathway occurs at or near the AV node, in WPW it is directly from the atria to the ventricles. These extra pathways cause the signal to get to the ventricles too fast and the signal is then sent back to the atria creating another electrical loop.
Patients that have the extra electrical pathways that occur in Wolff-Parkinson-White syndrome are born with them. This syndrome affects patients of all ages, including infants. However, symptoms often first occur in their teens and 20’s. Patients with WPW are also more likely to develop other arrhythmias later in life like atrial fibrillation and ventricular tachycardia.
Wolff-Parkinson-White syndrome symptoms include dizziness, syncope, and palpitations. Patients with WPW can also fatigue easily with exercise. WPW can be easily fixed with a procedure called ablation.