Patients and Families

Definition

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is an inherited heart rhythm disorder that affects the heart muscle, also known as the myocardium.

Causes

ARVC is a heritable condition which means it can be passed on through families. It is a genetic condition which means it is caused by a change or mutation in one or more genes. The heart muscle is held together by a machinery of proteins, much like train cars are held together by couplers. Many patients with ARVC have changes in their genes that are the blueprints for these couplertype proteins, making the connection between heart cells weaker over time. These changes cause the heart to be more susceptible to damage from mechanical stress (for example, during exercise when the heart is beating harder and faster). Further, this can increase the risk of electrical heart rhythm problems, or arrhythmias. Arrhythmias in the ventricles, the bottoms chambers of the heart muscle, can have serious consequences including fainting and sudden cardiac arrest.

Testing

If a patient is suspected to have ARVC, physicians may suggest a 12-lead ECG, exercise stress test, transthoracic echocardiography and a cardiac MRI.

Genetic testing may also be considered.

Treatment

Patient treatment and therapy will depend on patient-specific features of the disease and patient preference.

Some options for treatments may include restriction of activity, use of an implantable cardioverter-defibrillator (ICD), medications (beta-blocking agents and antiarrhythmic medications), and/or radiofrequency ablation.

Definition

Brugada syndrome (BrS) is a rare inherited arrhythmia that is associated with a characteristic ECG pattern called a Brugada sign. Individuals with BrS are at risk of arrhythmias that may result in syncope or sudden death. BrS affects more men than women and the average age at which symptoms appear is 40 years, although, symptoms have been reported in patients from newborn to 84 years.

Causes

Brugada syndrome is a genetic disease and a heritable condition.

Symptoms

Many patients with Brugada syndrome show no symptoms. Some patients may present with syncope, seizures, feelings of irregular heartbeats or palpitations, or sudden cardiac arrest.

Testing

If a patient is suspected to have Brugada syndrome, physicians may suggest a 12-lead ECG, exercise stress test, and transthoracic echocardiography.

In some patients, to further clarify whether Brugada syndrome is present, a procainamide test will be suggested. A procainamide test allows the visualization of electrical patterns that are provocable. Patients will receive an infusion of procainamide, a sodium channel blocking medication used for the treatment of heart rhythm disorders, and ECGs will be collected before, during and after the procainamide infusion looking for any abnormalities in the ECGs. This test is performed in the hospital and typically requires 2 to 3 hours

Genetic testing may also be considered.

Treatment

For patients diagnosed with Brugada syndrome, treatment is primarily focused around the prevention of cardiac arrest. Patients receive lifestyle advice such as avoiding medications that can exacerbate the condition (visit www.brugadadrugs.org for a full list of drugs to avoid) and treat fever with Acetaminophen (ie. Tylenol). Patients at high risk of sudden cardiac arrest may be offered implantable cardioverter defibrillators (ICDs).

Definition

Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is characterized by life-threatening heart racings affecting the ventricles (ventricular tachycardia) or irregular, fast beating of the ventricles (ventricular fibrillation) during times of intense emotional or physical stress. The average age at which symptoms of CPVT appear is between 7 and 9 years of age, although symptoms may appear as late as your 40's. If untreated, this condition can be lethal. Up to 80% of diagnosed individuals experience one or more fainting spells and approximately 30% experience cardiac arrest. CPVT is thought to be far less common than other arrhythmias, but does affect otherwise healthy infants, children, adolescents and adults. The true prevalence of CPVT remains unknown but it is estimated to be 1 in 10,000.

Causes

Patients often present in childhood or in young adulthood. CPVT is a genetic disease and a heritable condition.

Symptoms

The symptoms include palpitations, fainting, or cardiac arrest, often precipitated by physical and/or emotional stress.

Testing

If a patient is suspected to have CPVT, physicians may suggest a 12-lead ECG, exercise stress test, and transthoracic echocardiography. In some cases, catecholamine provocation testing may be considered.

Catecholamine provocation testing, or drug infusion testing, is used to simulate the emotional or physical stress that leads to the irregular heart rhythms seen in patients with CPVT. Like in procainamide testing for Brugada, patients will receive an infusion of catecholamines and be monitored by ECG looking for any irregular heart rhythms.

Genetic testing may also be considered.

Treatment

First line treatment typically consists of daily medications in the form of a beta blocker. Other treatments including a calcium channel blocker, sodium channel blocker and or an implantable cardioverter defibrillator (ICD) may also be considered in selected patients.

Definition

The term early repolarization (ER) is used to characterize a QRS-T variant on the electrocardiogram (ECG) consisting of appearance of a J wave and J point elevation, with or without an ST segment elevation. Historically, ER has been considered a marker of good health because it is more prevalent in athletes, younger persons, and at slower heart rates.

Definition

Idiopathic ventricular fibrillation (VF) is defined as a spontaneous ventricular fibrillation in the absence of any structual heart disease, including coronary artery disease, valvular heart disease, myocarditis, cardiomyopathy or electrophysiological diseases such as Long QT Sydrome, Brugada Syndrome or Wolff-Parkinson-White Syndrome.

Definition

Hypertrophic cardiomyopathy (HCM) is a genetic disease and an inherited condition affecting the heart muscle. This disease is characterized by marked increase in the ventricle muscle cells causing the walls of the ventricles to become thickened (ventricular hypertrophy). The thickened heart muscle can make it harder for the heart to pump blood.

Causes

HCM is an inherited condition that is caused by mutations in the genes responsible for making heart muscle proteins.

Symptoms

HCM can produce a number of different symptoms including fatigue, shortness of breath, chest pain, palpitations, fainting, blackouts, seizures, and sudden cardiac arrest.

Testing

In those patients with suspected HCM, an electrocardiogram and cardiac imaging to identify left ventricular hypertrophy are suggested. If there is evidence of HCM, 24-hour ECG monitoring, stress testing and a cardiac MRI may also be performed.

Genetic testing may also be considered.

Treatment

Treatment for patients with HCM is targeted at symptom relief and a patient specific risk of sudden cardiac arrest. Treatment options include: lifestyle recommendations, activity restriction, medical therapy, surgical and minimally invasive surgery. ICDs are considered in patients at high risk of sudden cardiac arrest.

Definition

Long QT Syndrome (LQTS) ia a rare heart condition that is estimated to affect roughly 1 in 2,000 people. The syndrome gets its name from its characteristic appearance on an electrocardiogram (ECG) where the time interval between the Q-wave and the T-wave is longer than usual. Alternatively, this means that the heart muscle will take longer than usual to recover electronically after a heart beat. It is important to know that patients with LQTS do not necessarily have to show this prolonged QT interval at all times.

Causes

Long QT syndrome is a genetic and a heritable condition. Acquired long QT syndrome is considered a separate clinical entity and is not the focus of this discussion.

Although rare, LQTS is the most common of genetic arrhythmias and there are subtypes of long QT syndrome based on the type of genetic mutations present with Types 1-3 being the most common.

Symptoms

Patients tend to present with palpitations, fainting, light-headedness, seizures or sudden cardiac arrest, often in childhood.

Testing

Along with clinical testing, the physician will investigate to ensure that the ECG pattern is not due to an acquired cause.

LQTS is most often diagnosed using ECG and exercise stress testing. As well, some patients may receive 24 hour Holter monitor testing and an echocardiogram.

Genetic testing may be considered.

Treatment

First line treatment typically consists of daily medications in the form of a beta blocker. Patients are advised to avoid medications that can exacerbate their condition. Other treatments sympathetic denervation and or an implantable cardioverter defibrillator (ICD) may also be considered in selected patients.

Definition

Short QT syndrome (SQTS) is genetic condition and a heritable disorder that is associated that is characterized by a finding of a shortened QT interval on an ECG. This means that the heart takes less time than usual to recover electrically in between heart beats.

Causes

SQTS is an inherited disorder which means that it runs in families and is caused by mutations in one or more genes. So far, 6 different genes have been implicated in the development of SQTS.

Symptoms

SQTS is seen in all age groups, but tends to present in children and young adults. The most common presentation for patients is syncope, blackouts, seizures, and cardiac arrest. Patients may also be asymptomatic or have palpitations.

Testing

All patients with suspected SQTS should undergo a routine surface ECG. Additional testing may include stress testing, echocardiography, and 24-hour ambulatory monitoring.

Treatment

Management of patients with SQTS varies with each patients’ clinical history, family history and genetics.

Definition

Sudden Infant Death Syndrome (SIDS) is the sudden unexplained death of a baby less than 1 year old.

Definition

Causes

Normally in the heart, the electrical systems of the atria and ventricles are only connected electrically via signals passing from the atria to ventricles at the atrioventricular node (AV) node. The AV node is important as it provides a delay of electrical impulses to ventricles, allowing the atria to fully empty into the ventricles before the ventricles contract. Patients with WPW have an additional electrical pathway that directly connects the atria and ventricles thereby allowing electrical activity to bypass the AV node.

This accessory pathway in patients with WPW is present from birth. Most often WPW is not an inherited condition, however some cases of WPW are inherited and run in families.

Symptoms

The majority of patients with WPW have no symptoms. A small number of patients develop arrhythmias and can present with palpitations, lightheadedness, fainting, blackouts, chest pain, or sudden cardiac arrest.

Testing

Diagnosis for patients with suspected WPW is most often made using an ECG looking for the characteristic WPW pattern.

Treatment

All patients with WPW can be offered treatment in the form of medications to treat symptoms, or definitive management with ablation which can offer a cure.