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Pediatric Diseases: Child’s Abnormal Cardiac Rhythm

Electric signal makes cardiac muscle cell to constrict or dilate.

Heart is beating perpetually to send blood out to entire body. The sinus node is responsible for this beating rhythm. Electric signal developed at this sinus node is conducted (impulse conducting system) to cardiac atria, atrioventricular node, bundle of His, and to Purkinje fiber accordingly, to conduct cardiac muscle constrict or dilate.

Abnormality of this contraction rhythm is called as abnormal cardiac rhythm. Abnormal cardiac rhythm is roughly grouped into three categories. (1) cardiac slowing: pulse becomes slower, (2) tachycardia: pulse becomes faster, and (3) Extrasystolic beat: pulse is disturbed. The case is rare for the children to have symptom in daily life, so most of the case is that abnormality is pointed out at heart examination at school. Below are described the outline of typical abnormal cardiac rhythm.

Extrasystolic beat which heart beats faster than natural rhythm

Extrasystolic beat means the heart is contracted one tempo earlier from natural beat rhythm, and they are two types, atrial extrasystole and ventricular extrasystole. In extrasystole, as signal comes earlier than normal in making heart acts earlier, not enough blood is pumped out by single beat. Therefore, although heart is beating, pressure caused by pulsation is weak so that it is unable to recognize as pulse, resulted it is like pulse is missed. But for the children and most of the cases, no symptom appears, no treatment is necessary. In case symptom appears, check whether or not tachyarrhythmia exists, by means of exercise electrocardiogram or Holter electrocardiogram. In case frequency of Extrasystolic increases, limitation of exercise is considered. There are many cases where extrasystole disappears by physical exercise. In these cases, treatment or physical exercise are unnecessary. Only periodical observation is conducted.

What is WPW syndrome?

WPW syndrome (Wolf-Parkinson-White syndrome) is a disease which pulls out frequent beat attack, infant case is over 220 heart rates, children case is over 180 heart rates, due to a development of another path (sub conducting path: typical one is bundle of Kent) than the original path in regard to the conducting path where signal impulsion is transferred from the atrium to the ventricle. It is diagnosed by typical waveform (Delta Wave) from electrocardiogram. Symptoms of palpitation, breast discomfort, faint are appeared and if it continued for a longer time, it becomes to cardiac arrest.

Treatments for frequent beat attack are; treatment of Valsalva maneuver (breath holding), press cold water or ice on face, carotid sinus massage, to reduce heart beat with exciting vagal nerve, or if possible intravenous injection of the drugs from blood vessel. In case of emergency for cardiac arrest, electric defibrillation is conducted.

To prevent these attacks, oral dosage of anti-arrhythmic drug is necessary, and in case when attacks repeats its occurrence, high frequency incineration to sub-conducting path by cardiac catheter is performed. This method is proved for high efficiency with definitive cure. However, it does not say that not all patients who was diagnosed as WPW syndrome at school health check develops frequent beat attack. In case when no frequent beat attack, special treatment or limitation of physical limitation are not necessary. Absence of sleep, extreme fatigue, stress may cause an attack, so that paying attention on these are necessary.

Abnormal Cardiac Rhythm which is life-threatening in childhood – Long QT Syndrome

Long QT syndrome is diagnosed by QT time extension in electrocardiograph waveform. It is known as protein, so called potassium/natrium ion channel, abnormality is the cause of the disease. Congenital long QT syndrome is the genetic disease and inherited to children with 50% provability rate regardless the gender. (autosomal dominant inheritance). Disease symptom differs substantially between individuals, and symptom may not appear even if gene has abnormality. Although it is a rare case, the disease accompanied with hearing impairment (congenital anacusis) in nature is handed down to children. After when aforementioned ventricular extrasystole has been produced frequently, when frequent cardiac attack (professionally it is called as torsade de pointes (TdP)) or ventricular fibrillation occur, then it possibly develops faint or sudden death, so that it is important as life-threatening in childhood.

β blocker like anti-arrhythmic drug is used for the prevention of frequent cardiac attack. When attacked, intravenous injection of anti-arrhythmic drug or electric defibrillation is necessary. On the other hand, not all of the student who is appointed as long QT syndrome has developed a cardiac attack. In case of having no attack, special treatment and/or limitation of exercise are unnecessary, but it is important to pay attention to the causes of the disease, such as not having the absence of sleep, having extreme fatigue, lack of salt/sugar at exercise, swimming (especially diving). There are 14 types in gene, and the treatment corresponding to each type are putting into practice, since the appearance factors for each symptom are different.