Cardiac Arrhythmia Syndromes (CAS)

An arrhythmia (also called dysrhythmia) is an abnormal rhythm of the heart, which can cause the heart to pump less effectively.

Arrhythmias can cause problems with contractions of the heart chambers by:

  • not allowing the ventricles (lower chambers) to fill with an adequate amount of blood, because an electrical signal is causing the heart to pump too fast.
  • not allowing a sufficient amount of blood to be pumped out to the body, because an electrical signal is causing the heart to pump too slowly or too irregularly.

In any of these situations, the heart may not be able to pump an adequate amount of blood to the body with each beat due to the arrhythmia's effects on the heart rate. The effects on the body are often the same, whether the heartbeat is too fast, too slow, or too irregular.

Cardiac Arrhythmia Syndrome is a general term used to describe sudden death due to cardiac arrest brought on by an arrhythmia.

Cardiac Arrhythmia Syndromes include:

  • Sudden Unexpected Death Syndrome (SUDS)
  • Sudden Adolescent Death Syndrome (SADS)
  • Sudden Athletic Death Syndrome (SAD)
  • Sudden Infant Death Syndrome (SIDS)
  • Long Q-T Syndrome

Undetected CAS Risks:

The following are the most common symptoms of arrhythmias. However, each child may experience symptoms differently. Symptoms may resemble other medical conditions or heart problems. Therefore, always consult your child's physician for a diagnosis.

Symptoms may include:

  • weakness
  • fatigue
  • palpitations
  • low blood pressure
  • dizziness
  • fainting

Facts About CAS

  • 1 out of every 143 children has a cardiac arrhythmia syndrome.
  • 20 children between the ages of 6 & 25 will die today from sudden cardiac arrest caused by a cardiac arrhythmia syndrome. (1)
  • 1 out of every 500 children has hypertrophic cardiomyopathy (HCM) the leading cause of sudden death in all young people. (2)
  • Cardiac arrhythmia syndrome is the leading cause of non-traumatic death in the adolescent athlete and young American population. (2)
  • Hypertrophic cardiomyopathy is the leading cause of sudden unexpected death in those under 35 years of age. (3)
  • Hypertrophic Cardiomyopathy (HCM) is more common in the United States than childhood leukemia, cystic fibrosis, Parkinson’s, Multiple Sclerosis, and ALS combined. (4)
  • Electrical cardiac diseases, such as Long QT syndrome, Short QT syndrome, Brugada syndrome, Lev Lenegre syndrome, Wolf Parkinson White syndrome (WPW), hypertrophic cardiomyopathy (HCM) and arrhythmogenic right ventricular cardiomyopathy (ARVC) can be identified by the resting ECG. (5)
  • Once a cardiac arrhythmia syndrome is detected and 1st and 2nd degree family members are tested, an average of nine additional cases are found.
  • Once diagnosed, these syndromes are treatable, and individuals with these conditions can have normal life spans and lifestyles.

Living with CAS:

An arrhythmia doesn’t have to be a death sentence. Once detected, your child’s physician can offer various treatment options based on the type of arrhythmia, the severity of symptoms being experienced, and the presence of other conditions (i.e., diabetes, kidney failure, heart failure) which can affect the course of the treatment.

Treatments may include:

Lifestyle Modifications

Factors such as stress, caffeine, or alcohol can cause arrhythmias. Your child's physician may order the elimination of caffeine, alcohol (teens and young adults), or any other substance believed to be causing the problem. If stress is suspected as a cause, your child's physician may recommend stress-reduction measures such as an exercise program or family therapy.


There are various types of medications which may be used to treat arrhythmias. If your child's physician chooses to use medication, the decision of which medication to use will be determined by the type of arrhythmia, other conditions which may be present, and other medications already being used by your child.


In this procedure, an electrical shock is delivered to the heart through the chest to stop certain very fast arrhythmias such as atrial fibrillation, supraventricular tachycardia, or sinus tachycardia. The patient is connected to an ECG monitor which is also connected to the defibrillator. The electrical shock is delivered at a precise point during the ECG cycle to convert the rhythm to a normal one.


This is an invasive procedure done in the electrophysiology laboratory, and involves a small, thin tube (catheter) being inserted into the heart through a vessel in the groin or arm. The procedure is done in a manner similar to the electrophysiology studies (EPS) described above. Once the site of the arrhythmia has been determined by EPS, the catheter is moved to the site. By use of a technique such as radiofrequency ablation (very high frequency radio waves are applied to the site, heating the tissue until the site is destroyed) or cryoablation (an ultra-cold substance is applied to the site, freezing the tissue and destroying the site), the site of the arrhythmia may be destroyed.


A permanent pacemaker is a small device that is implanted under the skin and sends electrical signals to start or regulate a slow heartbeat. A permanent pacemaker may be used to make the heart beat if the heart's natural pacemaker (the sinoatrial, or SA, node) is not functioning properly and has developed an abnormal heart rate or rhythm or if the electrical pathways are blocked. Pacemakers are typically used for slow arrhythmias such as sinus bradycardia, sick sinus syndrome, or heart block.

In infants and young children, pacemakers are usually placed in the abdomen. The wires that connect the pacemaker to the heart are placed on the outside surface of the heart. This position is beneficial because the fat in the abdomen protects the pacemaker and pacemaker wires from injury that might occur during everyday childhood activities such as climbing and falling.

School-aged children and adolescents may have the pacemaker placed in the shoulder area just under the collarbone. The pacemaker wires are often placed inside the superior vena cava, a large vein that connects to the right atrium, and then guided inside the heart.

Implantable Cardioverter Defibrillator

An implantable converter defibrillator (ICD) is a small device, similar to a pacemaker, that is implanted under the skin, often in the shoulder area just under the collarbone. An ICD senses the rate of the heartbeat. When the heart rate exceeds a rate programmed into the device, it delivers a small, electrical shock to the heart to slow the heart rate. Many newer ICDs can also function as a pacemaker by delivering an electrical signal to regulate a heart rate that is too slow. ICDs are typically used for fast arrhythmias such as ventricular tachycardia.


Surgical treatment for arrhythmias is usually done only when all other appropriate options have failed. Surgical ablation is a major surgical procedure requiring general anesthesia. The chest is opened, exposing the heart. At the site where the arrhythmia is located, the tissue is destroyed or removed in order to eliminate the source of the arrhythmia.


(1) Heart Rhythm Society,

(2) The Teague Ryan Sudden Child Cardiac Arrhythmia Syndromes Screening and Education Act of 2005

(3) B. Maron et al. “Sudden death in young competitive athletes: clinical, demographic, and pathological profiles.” JAMA, 1996.

(4) The Teague Ryan Sudden Child Cardiac Arrhythmia Syndromes Screening and Education Act of 2005, also, B. Maron, “Sudden Death in Young Athletes” New England Journal of Medicine, Sept 11, 2003.

(5) Corrado D, Pelliccia A, Bjørnstad HH, et al.. “Cardiovascular pre-participation screening of young competitive athletes for prevention of sudden death: proposal for a common European protocol. Consensus statement of the Study Group of Sport Cardiology of the Working Group of Cardiac Rehabilitation and Exercise Physiology and the Working Group of Myocardial and Pericardial Diseases of the European Society of Cardiology” Eur Heart J 2005;26:516–20, also in “Preparticipation cardiovascular screening in young athletes” British Journal of Sports Medicine, July 7, 2009.