Sudden arrhythmia death syndromes (SADS) are genetic heart rhythm abnormalities conditions that can cause sudden death in young, apparently healthy people, who may be undiagnosed. These conditions can be treated and deaths can be prevented. Warning Signs: family history of unexpected, unexplained sudden death under age 40; fainting or seizure during exercise, excitement or upon sudden shock or surprise; consistent or unusual chest pain and/or shortness of breath during exercise.

SADS conditions are passed down from parent to child with each child of an affected parent having a 50% chance of inheriting the condition. It is estimated that over half of the 4000 SADS deaths each year of children, teens, or young adults had one of the top two warning signs: 1) family history of a SADS diagnosis or sudden unexplained death (usually undiagnosed and untreated) of a family member, or 2) fainting

Warning Sign

You should see a doctor if you have experienced:

Family history of unexpected, unexplained sudden death in a young person

Fainting (syncope) or seizure during exercise, excitement or upon sudden shock or surprise

Consistent or unusual chest pain and/or shortness of breath during exercise

Long QT Syndrome (LQTS)

LQTS is a disturbance of the heart’s electrical system, resulting in an abnormality of the heartbeat or rhythm of the heart. It is caused by abnormalities of microscopic pores in the heart cells called ion channels.

Nearly half of patients with LQTS NEVER HAVE A SYMPTOM!


Cardiac arrest or sudden fainting due to trademark cardiac arrhythmia called torsade de pointes. Most often, these events occur during or right after physical exertion, with emotional stress or startle (alarm clock). Sometimes they occur during sleep.

Family history of a SADS diagnosis, SADS symptoms, or sudden unexplained death of a family member under 40 years of age.


  • Electrocardiogram (ECG) and more than 1 resting ECG
  • A treadmill stress test with an ECG
  • An epinephrine, procainamide (Brugada), or catecholiminergic (CPVT) drug study - where the effects of drugs on the heart are analyzed.
  • A Holter or event monitor
  • Genetic Testing

Treatment options

  • Medication, beta blockers
  • ICD
  • AED
  • Left Cardiac Sympathectomy Denervation (LCSD)
  • Avoid drugs that can prolong the QT Interval (Drugs to avoid - LQTs)

Brugada Syndrome

Brugada syndrome is a hereditary arrhythmia caused by abnormalities in myocardial ion channels. Usually does not cause any noticeable symptoms. Many people with Brugada syndrome do not know they have the disease.


Symptoms includes severe wheezing or dyspnea, especially at night, dizziness, fainting, irregular heartbeat or palpitations, extremely fast and chaotic heartbeat, and even epileptic seizures.


A diagnosis of Brugada syndrome is made with an abnormal resting ECG, ECG during fever, ECG with drug (procainamide) studies, and genetic testing. Genetic testing is positive in 40% of affected patients.

Treatment options

Treatment options are few. At present if a person has a definitive diagnosis and symptoms, an ICD is recommended. An ICD is not the answer for every patient. Some research suggests that quinidine may help some patients. Patients should also avoid drugs which block the sodium channels in the heart. Avoid drugs that can provoke the Brugada pattern.

Drugs to avoid for Brugada Syndrome patients

Hypertrophic Cardiomyopathy (HCM)

To better understand what Hypertrophic Cardiomyopathy (HCM) is let's first talk about how cardiomyopathies are described.

Cardiomyopathy is a condition in which the muscle of the heart is abnormal in the absence of an apparent cause. This terminology is purely descriptive and is based on the Latin deviation. HCM is a primarily and usually familial cardiac disorder with heterogeneous expression, unique pathophysiology, and a diverse clinical course, for which several disease causing mutations in the genes encoding proteins of the cardiac sacomere have been reported. There are some forms of HCM that are currently being debated by the medical community regarding how they should specifically be defined because the cause of the hypertrophy in these cases is now understood to be from other mutations impacting either the storage of glycogen or lysosomal storage within the heart.

While HCM has typically been recognized by its structure ie., hypertrophy, the electrical functions of the heart are also adversely affected. There are four types of cardiomyopathy: “Hypertrophic”, “Dilated”, “Restrictive” and “Right ventricular”.


The main feature of hypertrophic cardiomyopathy is an excessive thickening of the heart muscle (hypertrophy literally means to thicken). Thickening is seen in the ventricular septal measurement (normal range .08-1.2cm), and in weight. In HCM, septal or wall measurements may be in the range of 1.3cm to 6.0+cm anywhere in the left ventricle. Heart muscle may also thicken in normal individuals as a result of high blood pressure or prolonged athletic training. Furthermore, there is a fine line between and athletic heart, hypertensive heart disease, and a heart with HCM.

In Hypertrophic Cardiomyopathy (HCM), the muscle thickening occurs without an obvious cause. In addition, microscopic examination of the heart muscle in HCM is abnormal. The normal alignment of muscle cells is absent and this abnormality is called “myocardial disarray”.


Hypertrophic Cardiomyopathy may be suspected because of family history, symptoms, a murmur or an abnormal EKG/ECG. Many symptoms or signs of Hypertrophic Cardiomyopathy are similar to various other conditions; therefore, it is important to follow doctor’s instructions on complete testing to assure accurate results. An EKG/ECG records the electrical signals of the heart. In Hypertrophic Cardiomyopathy the EKG/ECG usually shows an abnormal electrical signal due to muscle thickening and disorganization of the muscle structure. In a minority of patients (approximately 10%) the ECG/ECG may be normal or show only minor abnormalities. EKG/ECG abnormalities are also not specific to Hypertrophic Cardiomyopathy and will be found in many other conditions.

Presently, the diagnosis of Hypertrophic Cardiomyopathy is made by an ultrasound scan of the heart called “echocardiogram” or “Echo” for short. Like the EKG/ECG, this is an entirely safe test. Excessive thickness of the muscle can be easily measured. Additional equipment called “Doppler” ultrasound can produce a color image of the blood flow within the heart and measure the contractions and filling of the heart. Turbulent flow can be detected using the doppler. Therefore, Echo/Doppler provides a very thorough assessment of Hypertrophic Cardiomyopathy.

MRI has been used in more frequent years to gain a more detailed image of the heart. MRI is the use of newer technology and can produce clearer pictures of the heart and also show the structure of the walls of the heart in such a way that scaring and fibrosis can be viewed.

After a diagnosis is made several other tests may be required. Holtor monitoring is a continuous recording of the heartbeat over a period of 24 to 48 hours. A holtor monitor is a simple and safe test that will detect irregularities of the heart beat (otherwise known as arrhythmia). Stress tests and Stress Echo’s may be used to monitor the heartbeat during exercise as well as blood pressure response and then the echo to see if there have been any structural changes due to the exercise. Cardiac catherization may follow but it is not used on all patients with HCM.

Treatment options

HCM has many treatment options that may be considered. Each patient will need to evaluate what is in their best interest both short term and long term before engaging in treatment for HCM. Treatments include:

  • Medication
  • ICD
  • Septal Reduction Therapy
  • Atrial Fibrillation Treatment
  • Heart Transplant

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)


ARVC is caused by a defect in the 'glue' that holds the muscle cells of the heart together. As the 'glue' breaks down, the muscle cells separate and some die. The body then tries to repair this by replacing the normal heart muscle cells with scar and fat tissue which do not conduct electrical signals and contract in the normal way. This allows abnormal 'short-circuits' to develop, which cause the heart rhythm abnormalities that define the condition.


  • Detailed record of symptoms, medical and family background and a physical examination
  • ECG (including a signal average ECG) and an ultrasound scan of the heart (echocardiogram, or echo)
  • Magnetic resonance imaging (MRI) scan
  • Exercise ECG and 24-hour ECG to record any palpitations or abnormal heart rhythms
  • If a specific genetic mutation has been identified as the cause of ARVC in an individual, family members can be tested for this same mutation with a blood test.

Treatment options

  • Lifestyle modifications such as not participate in competitive, strenuous physical activities since this can be a trigger for dangerous heart rhythm disturbances
  • Medication including beta-blockers, sotalol and amiodarone
  • Ablation : the particular area of the heart causing the abnormal rhythm and this area is cauterised – or burnt. However, new problematic areas of the heart can develop over time
  • Implantable cardiac defibrillator (ICD)
  • Regular check-ups

Wolff-Parkinson-White Syndrome (WPW)

WPW Syndrome is electrical abnormalities of the heart that are caused by electrical conduction over an accessory-wide pathway (a microscopic, hair-like electrical connection between the upper and lower chambers of the heart, atria and ventricles, respectably). This accessory pathway is in addition to the AV node, the only normal electrical conductor between the atria and ventricles.


The cause of WPW syndrome is not known. In most cases it is associated with a structurally and functionally normal heart, though occasionally can be associated with congenital heart disease or heart muscle abnormalities.


It is generally not considered to be hereditary, except in the very rare instance when associated with genetic mutation predisposing to WPW syndrome and hypertrophic cardiomyopathy (HCM).


Tachycardia presenting with palpitations and occasionally lightheadedness is the most common.


  • Occasionally WPW syndrome is diagnosed by the presence of the classic ECG findings on an ECG obtained for other purposes; patients may be completely asymptomatic, with no clinical palpitations or tachycardia symptoms. The most common presentation is tachycardia presenting with palpitations and occasionally lightheadedness.
  • The most common tachycardia is called orthodromic reentry tachycardia (ORT). This looping tachycardia travels electrically down the AV node to the ventricles and then back to the atria over the accessory pathway. In patients with an otherwise functionally normal heart this is rarely a life threatening tachycardia, but may be frequent, sustained, and symptomatic with light headedness, dizziness, and some shortness of breath or chest discomfort. This tachycardia generally starts and stops precipitously.
  • Cardiac catheterization with diagnostic electrophysiologic testing can be used to assess the electrical properties of the accessory pathway.
  • In contrast to many other types of tachycardias, WPW syndrome can be regarded as potentially “curable” with catheter ablation techniques. Radiofrequency ablation uses electrical heating to eliminate conduction over the accessory pathway, while in contrast cryoablation uses freezing to destroy the pathway.

Timothy Syndrome (TS)

Timothy Syndrome is a rare type of Long QT Syndrome. There are two types of Timothy Syndrome: Type 1 in which webbed fingers and/or toes are present (syndactyly), and Type 2 which is not associated with syndactyly.


  • Cardiac arrest or fainting due to trademark cardiac arrhythmia called torsade de pointes
  • Family history – of a SADS diagnosis, SADS symptoms, or sudden unexplained death of a family member under 40 years of age
  • Syndactyly (webbed fingers and/or toes)
  • Severe developmental delays; sometimes autism


  • ECG
  • Fetal ultrasound may show significantly reduced heart rates

Treatment options

  • Medication, beta blockers
  • ICD


Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)

Catecholaminergic polymorphic ventricular tachycardia or CPVT is a condition that results in ventricular rhythm problems (bidirectional and polymorphic ventricular tachycardia and ventricular fibrillation) that can cause fainting or sudden death. Events usually occur with exercise or during stress. CPVT is caused by abnormalities in the way the heart muscle cells handle calcium.


  • Fainting – caused by ventricular tachycardia - usually with exercise or other activities that are associated with high adrenaline levels.
  • Cardiac arrest if the ventricular tachycardia degenerates into ventricular fibrillation. Cardiac arrest may be the first symptom in CPVT patients.


  • CPVT is diagnosed primarily by either treadmill stress testing to provoke rhythm abnormalities, orcatecholamine provocation testing
  • In children too young to perform exercise testing a 24-hour Holter monitor may help with the diagnosis. (In children with CPVT, the heart muscle function and the heart structure are normal). Note: a resting ECG that is usually normal
  • Genetic Testing

Short QT Syndrome (SQTS)

A genetic heart abnormality in which the duration of the ECG QT-interval is between 210 and 340 milliseconds while in normal people it is between 350 and 440 milliseconds. In contrast to its mirror-image disorder long QT syndrome, there is not much known about SQTS. However, impressive progress has been made in the genetics of SQTS.


Having a short QT-interval in the ECG does not in itself cause any symptoms, but it can lead to two different types of rhythm disturbance, which in turn can cause symptoms.

The first type is atrial fibrillation, which is an irregular heart rhythm originating in the upper chambers (atria) of the heart. It causes palpitations, shortness of breath, dizziness, chest tightness and fatigue. It can occur in short episodes, starting and stopping by themselves, or it can become a more permanent condition.

The second type is ventricular tachycardia or fibrillation. It is a very fast rhythm disturbance originating in the lower chambers (ventricles) of the heart. It is a much more serious problem, which can lead to sudden cardiac death.

Rhythm disturbances from both upper and lower chambers of the heart can in addition lead to passing out spells (syncope), where a person may wake up by him/herself.

Treatment options

An ICD is recommended as first-line treatment to prevent sudden cardiac death. Quinidine has thus far proved to be the most effective drug but should be used with an ICD.