Arrhythmias

Pediatric or adolescent arrhythmias come in all different kinds, and it depends on where in the heart the arrhythmia is located (top, middle or bottom of the heart).

It is very fortunate when the cardiologist knows what kind of arrhythmia it is without further testing, although often an ECG or a Holter Monitor will allow the doctor to evaluate the rhythm.

Adolescents often come into an echo lab with symptoms of tachycardia, syncopal episodes, bradycardia, heart block, chest pain and various other patterns that may or may not be apparent directly.

Exercise stress testing is an appropriate procedure used in order to stimulate the arrhythmia. This is also a valuable tool that evaluates exercise tolerance and the presence of ischemia (lack of oxygen to the heart muscle) and other symptoms that are not present at rest.

Electrophysiology may be a method that is used in the event of life threatening situations.

There are times when an implantable defibrillator may be needed to control arrhythmias, but often drug therapy is sufficient. Pacemakers are usually used depending on the location of the arrhythmia, especially if there is a significant malfunction of the heart’s conduction system.

More aggressive treatment (electrophysiology, ablation, and pacemakers) are usually reserved for patients that do not respond to drug therapy.

Sinus Arrhythmia

This is common in children and adolescents, and is characterized by a normal sinus rhythm that is irregular. It is not dangerous or necessarily abnormal.

Tachycardia

This is the most common cause of arrhythmia in a fetus or young adult and is often due to a “short circuit” in the wiring of the heart such as a bundle branch block, or may be caused by such abnormalities as cardiomyopathy or other structural defects in the heart.

Wolff-Parkinson-White Syndrome (WFW)

Essentially a short circuit in the wiring of the top part of the heart, or the atria which causes pre-excitation of the ventricles before the normal impulse is supposed to get to the ventricles. This is more common in patients with such abnormalities as Ebstein’s malformation or transpositions.

Irregular tachycardia, atrial fibrillation, syncope, palpitations are more common developments, and the risk of sudden death is higher. Ablation (zapping the short circuit with a catheter), or drug therapy is the most common treatments.

Atrial Conduction Abnormalities

These are essentially “short circuits” in the top part of the heart that lead to such arrhythmias as atrial fibrillation, atrial flutter and nodal problems (those areas of the heart that conduct bio-electric impulses from one part of the heart to another, or the SA and AV nodes).

Some nodal problems are referred to as “sick sinus syndrome”. Drug therapy and ablation are common solutions to these types of problems and have a high success rate.

Some arrhythmias are inherited and are associated with various cardiomyopathies, or primary diseases of the musculature of the heart or its electrical system, e.g. hypertrophic cardiomyopathy and/or the disorders described above.

Echocardiography

There are often stories in the newspaper of young adults who are athletes that die during strenuous exercise. Various arrhythmias can be the cause, and are important to diagnose with a pediatric cardiologist, and often result in a treadmill stress test.

 However, the most common cause of sudden death during exercise that I am aware of are two congenital defects, “anomalous coronary arteries” and “IHSS” (or idiopathic hypertrophic sub-aortic stenosis).

What the heck does that mean?  For parents and those who are not technologists, that means that the arteries that feed the heart muscle (coronary arteries) are not connected up properly, or that there is an intrinsic, inherited disease of the heart muscle that is enlarged and is preventing blood from exiting the heart when it is pumping at a high rate. These defects are discussed in other posts, but my experience is that they are the most common causes of sudden death upon heavy exertion.

My rule of thumb as an echocardiographer is to check for these (and any other defects) in any young patient.

Ken Heiden RDCS, RVT

“Congenital Heart Defects, Simplified”

www.HeartDefectsSimplified.com