Ablation

A cardiac ablation is a minimally invasive procedure used to treat certain abnormal heart rhythms (arrhythmias). It works by creating small areas of scar tissue to interrupt abnormal electrical signals in the heart.

ACE Inhibitors (ACEi)

A class of medications that relax blood vessels, lower blood pressure, reduce strain on the heart, and help slow the progression of heart failure.

AED (Automated External Defibrillator)

A portable emergency device that checks a person’s heart rhythm during cardiac arrest and can deliver an electrical shock if needed. AEDs are designed to give spoken or visual instructions so members of the public can use them while emergency help is on the way.

Amino Acid

A small building block that the body uses to make proteins. Proteins help our cells and organs work properly. The order of amino acids in a protein is determined by our genes, so a genetic change can sometimes affect how a protein is made or functions.

Angiotensin Receptor Blockers (ARBs)

Medications that help relax blood vessels, lower blood pressure, and reduce the workload on the heart.

Angiotensin Receptor-Neprilysin Inhibitor (ARNI)

A newer class of heart failure medication, such as sacubitril/valsartan (Entresto), that improves heart function, reduces symptoms, and lowers the risk of hospitalization and death in many patients with heart failure.

Arrhythmia

An abnormal heart rhythm that may cause the heart to beat too fast, too slow, or irregularly. Some arrhythmias are harmless, while others can interfere with the heart’s ability to pump blood and may require treatment. Arrhythmias are one of the hallmark features of PLN-cardiomyopathy.

Arrhythmogenic Cardiomyopathy (ACM/ARVC)

A form of cardiomyopathy characterized by replacement of healthy heart muscle with scar and fatty tissue, increasing the risk of ventricular arrhythmias and sudden cardiac arrest. PLN can cause an arrhythmogenic phenotype affecting either or both ventricles.

Asymptomatic

Having a disease, condition, or genetic change without having noticeable symptoms. Someone can feel completely healthy while still having changes that can be detected through genetic testing, heart monitoring, imaging, or other medical tests

Atrial Fibrillation (AFib)

A common irregular heart rhythm originating in the upper chambers of the heart (atria). AFib increases the risk of stroke, heart failure, and other cardiovascular complications. When the atria quiver (Afib) or beat too fast (flutter), blood can pool instead of moving out completely. When blood already moves slower through the chambers, it increases the risk of clot formation. A clot traveling to the brain can cause a stroke.

Atrioventricular Block (AV block)

Atrioventricular (AV) block is partial or complete interruption of impulse transmission from the atria to the ventricles.

Atrioventricular Node (AV node)

The atrioventricular node or AV node is a part of the electrical conduction system of the heart that coordinates the top of the heart. It electrically connects the atria and ventricles.

Beta Blockers

Medications also known as beta-adrenergic blocking agents, are medications that improve your heart muscle function, sometimes to near normal levels. They work by blocking the effects of the hormone epinephrine, also known as adrenaline, which lets your heart muscle become healthier. They may also tend to reduce your blood pressure, which if elevated, is another beneficial effect.

Body Mass Index (BMI)

Body Mass Index (BMI) is a person’s weight in kilograms divided by the square of height in meters.

Bradycardia

Bradycardia is a slower than normal heart rate. If you have bradycardia, your heart beats fewer than 60 times a minute.

Calcium

A mineral that is important for much more than strong bones. In the heart, calcium moves in and out of heart-muscle cells to help control each heartbeat, both contraction and relaxation. Problems with how heart cells handle calcium can affect how well the heart works.

Cardiac MRI (CMR)

A detailed imaging test that evaluates heart structure, function, and tissue characteristics. In PLN, cardiac MRI is especially important because it can detect fibrosis (scar tissue) using Late Gadolinium Enhancement (LGE) before symptoms develop.

Cardiac Resynchronization Therapy (CRT)

A specialized pacemaker that improves coordination between the right and left sides of the heart, helping some patients with heart failure pump more efficiently.

Cardiac Resynchronization Therapy Defibrillator (CRT-D)

A cardiac resynchronization therapy pacemaker or “biventricular pacemaker,” which includes a built-in implantable cardioverter defibrillator (ICD).

Cardiomyopathy

A disease of the heart muscle that affects its ability to pump blood effectively. PLN can cause several forms of cardiomyopathy, including dilated and arrhythmogenic cardiomyopathy.

Cardiopulmonary Exercise Testing (CPET)

Cardiopulmonary Exercise Testing is a non-invasive method used to assess the performance of the heart and lungs at rest and during exercise.

Congestive Heart Failure (CHF)

Congestive heart failure is a weakness of the heart that leads to a buildup of fluid in the lungs and surrounding body tissues. 

Defibrillation

The delivery of an electrical shock to the heart to stop certain life-threatening abnormal heart rhythms and allow a more normal rhythm to return. A defibrillator may be an external device used during an emergency or an implanted device, such as an ICD.

Dilated Cardiomyopathy (DCM)

A condition in which the heart muscle becomes enlarged and weakened, reducing its ability to pump blood effectively. PLN is one of many genetic causes of DCM.

DNA

The body’s genetic instruction manual. DNA contains the information our cells use to grow, function, and make proteins. Sections of DNA are called genes.

Echocardiogram (Echo)

An ultrasound of the heart used to evaluate heart size, valve function, and pumping ability.

Edema

Swelling caused by extra fluid collecting in the body’s tissues. It is often noticed in the feet, ankles, or legs. In people with heart disease, edema can sometimes occur when the heart is not pumping effectively and fluid begins to build up.

Ejection Fraction (EF or LVEF)

A measurement of how much blood the left ventricle pumps with each heartbeat. A normal EF is generally 55%–70%, although some PLN carriers can have normal EF despite early disease.

Electrocardiogram (ECG or EKG)

A simple test that records the heart’s electrical activity and can identify conduction abnormalities and arrhythmias.

Electrophysiologist (EP)

A cardiologist who specializes in diagnosing and treating heart rhythm disorders. Many individuals with PLN are followed by an electrophysiologist in addition to a general cardiologist.

Endomyocardial Biopsy (EMB)

Endomyocardial biopsy is a procedure that percutaneously obtains small amounts of myocardial tissue for diagnostic, therapeutic, and research purposes.

Extravascular Implantable Cardioverter Defibrillator (EV-ICD)

A newer type of implantable defibrillator placed outside the heart and blood vessels that monitors for life-threatening ventricular arrhythmias and delivers therapy when needed. Unlike traditional transvenous ICDs, it avoids leads inside the heart while still providing pacing for certain arrhythmias.

Fibrosis

The replacement of healthy heart muscle with scar tissue. Fibrosis is a hallmark of PLN-cardiomyopathy and contributes to both weakened heart function and dangerous arrhythmias. It is often detected using cardiac MRI with Late Gadolinium Enhancement (LGE).

Gene

A section of DNA containing instructions that help the body make a specific protein or perform a particular function. Genes are inherited from our biological parents. Changes in certain genes can cause or increase the risk of inherited diseases.

Gene Therapy

A type of treatment designed to address disease at the genetic level. Depending on the therapy, it may add, replace, repair, silence, or change the activity of genetic material to help cells function more normally. Gene therapies are still being researched for many heart conditions.

Genetic Counselor

A healthcare professional trained to help individuals and families understand inherited conditions, interpret genetic test results, discuss family screening, and provide education and emotional support.

Genetic Test

A test that looks at a person’s DNA for changes, called variants or mutations, that may cause or increase the risk of certain conditions. Genetic testing can sometimes help identify an inherited heart condition and determine whether family members should also consider testing.

• Cascade Genetic Testing: Genetic testing offered to biological relatives after a disease-associated genetic variant has been identified in a family. It can help determine which family members carry the same variant and may benefit from appropriate heart screening or follow-up.

Genotype

A person’s genetic makeup. In genetic heart disease, the term may be used to describe whether someone carries a particular genetic variant, such as a disease-associated variant in the PLN gene.

Heart Failure (HF)

A chronic condition in which the heart cannot pump enough blood to meet the body’s needs. Symptoms commonly include fatigue, shortness of breath, and swelling.

Holter Monitor

A portable heart monitor worn continuously, usually for 24–48 hours or longer, to detect intermittent arrhythmias.

Hypertrophic Cardiomyopathy (HCM)

Hypertrophic cardiomyopathy is a condition in which a portion of the heart becomes thickened without an obvious cause. This results in the heart being less able to pump blood effectively.

Implantable Cardioverter Defibrillator (ICD)

A device implanted under the skin that continuously monitors heart rhythm and delivers life-saving pacing or shocks when dangerous ventricular arrhythmias occur.

Inherited Condition

A condition that can be passed through biological families through genes. Inheriting a genetic variant associated with a condition does not always mean that a person will develop symptoms or develop the same severity of disease as another family member.

Late Gadolinium Enhancement (LGE)

A specialized cardiac MRI technique that identifies scar tissue (fibrosis) within the heart muscle. LGE is one of the earliest imaging findings seen in many PLN carriers and helps physicians assess disease progression.

Left Bundle Branch Block (LBBB)

Left bundle branch block affects the heart’s electrical conduction system. When you have left bundle branch block, the left branch of this conducting system is partially or completely blocked. This causes the left ventricle to contract a little later than it should.

Left Ventricular Assist Device (LVAD)

A mechanical pump that helps the heart circulate blood when it becomes severely weakened. It may serve as a bridge to heart transplantation or as long-term therapy.

Left Ventricular Ejection Fraction (LVEF)

Left ventricular ejection fraction is the measurement of how much blood is being pumped out of the left ventricle of the heart (the main pumping chamber) with each contraction. 

Pacemaker

A pacemaker is a small device that’s placed in the chest or abdomen to help control abnormal heart rhythms. This device uses electrical pulses to prompt the heart to beat at a normal rate. Pacemakers are used to treat arrhythmias, which are problems with the rate or rhythm of the heartbeat.

Palpitations

The sensation of a racing, pounding, fluttering, or skipped heartbeat. Palpitations may be caused by premature beats or other arrhythmias.

Penetrance

The likelihood that someone carrying a genetic mutation will develop symptoms. PLN has incomplete and age-dependent penetrance, meaning not every carrier develops heart disease, and symptoms can appear at different ages.

Phenotype

The observable way a genetic condition presents. In PLN, some individuals develop predominantly arrhythmias, others develop dilated cardiomyopathy or heart failure, while some remain asymptomatic for many years.

Premature Atrial Contractions (PACS)

Premature atrial contractions, also known as atrial premature complexes (APC) or atrial premature beats (APB), are a common cardiac dysrhythmia characterized by premature heartbeats originating in the atria.

Premature Ventricular Contraction (PVC)

An extra heartbeat that begins in the ventricles and may feel like a skipped beat or flutter. PVCs are common in PLN and may increase as the disease progresses.

Protein

A molecule made from amino acids that performs important jobs throughout the body. Proteins help build tissues, send signals, transport substances, and control how cells function. Genes provide the instructions for making proteins.

RNA

A molecule that helps cells use the instructions stored in DNA. One important type of RNA acts like a temporary copy of genetic instructions, telling cells which proteins to make.

RNA-based therapies/medicine

A type of treatment that uses or targets RNA to change how cells make certain proteins. Instead of permanently changing a person’s DNA, many RNA-based treatments work by changing, blocking, replacing, or correcting the genetic messages cells use to make proteins. Researchers are studying RNA-based approaches for many genetic diseases, including some inherited heart conditions.

SA Node

The SA node is the heart’s natural pacemaker. The SA node consists of a cluster of cells that are situated in the upper part of the wall of the right atrium (the right upper chamber of the heart). The electrical impulses are generated there.

S-ICD (Subcutaneous ICD)

A less invasive defibrillator implanted under the skin without leads entering the heart or blood vessels. It protects against sudden cardiac arrest but does not provide pacing for slow heart rhythms.

Sudden Cardiac Arrest (SCA)

A life-threatening emergency in which the heart suddenly stops beating effectively due to an electrical disturbance. Immediate CPR and defibrillation are essential for survival.

Sudden Cardiac Death (SCD)

An unexpected death resulting from sudden cardiac arrest. One of the primary goals of monitoring and treatment in PLN is to reduce the risk of SCD.

Supraventricular Tachycardia (SVT)

Supraventricular tachycardia, also called paroxysmal supraventricular tachycardia, is defined as an abnormally fast heartbeat. It’s a broad term that includes many forms of heart rhythm problems (heart arrhythmias) that originate above the ventricles (supraventricular) in the atria or AV node

Syncope (fainting):

Syncope (fainting or a “blackout spell”). Syncope is the medical term for temporary loss of consciousness caused by a sudden decrease in blood flow to the brain. If one does, it typically occurs quickly, lasts only a short time, and is followed by a complete recovery. In people with PLN R14Del, syncope can sometimes be a warning sign of a dangerous heart rhythm (arrhythmia), such as ventricular tachycardia (VT), and should never be ignored. However, fainting can also result from other causes, including low blood pressure, dehydration, certain medications, or vasovagal (reflex) episodes. 

• Near-Syncope is the medical term for a someone who develops the same symptoms but recover before actually fainting. Symptoms may include dizziness, lightheadedness, tunnel vision, ringing in the ears, nausea, sweating, weakness, or feeling as though you are about to pass out. These episodes can last anywhere from a few seconds to several minutes and are often followed by fatigue, nausea, or feeling “drained” for several hours.

• Vasovagal syncope is the most common cause of fainting and occurs when the body’s normal reflexes temporarily trigger a sudden drop in heart rate and blood pressure, reducing blood flow to the brain. This results in a brief loss of consciousness, usually followed by a rapid and complete recovery. Common triggers include prolonged standing, dehydration, heat exposure, emotional stress, fear, pain, or seeing blood. Many people experience warning signs before fainting, such as dizziness, lightheadedness, blurred vision, nausea, sweating, feeling warm, ringing in the ears, and/or feeling flushed. Loss of consciousness typically lasts only a few seconds to one or two minutes, with most individuals recovering within 5 to 30 minutes, although fatigue or mild weakness may persist for several hours. Although vasovagal syncope is generally considered benign and is not typically caused by an underlying heart rhythm disorder, anyone with PLN R14del who experiences fainting should contact their cardiologist promptly. Because PLN increases the risk of potentially life-threatening ventricular arrhythmias, it is important to determine whether the episode was truly vasovagal or related to the heart. 

• The Vagus Nerve is one of the body’s largest nerves and plays a major role in the autonomic nervous system (which controls involuntary functions such as heart rate, blood pressure, breathing, and digestion). During a vasovagal episode, the Vagus nerve becomes overstimulated, causing the heart rate to slow and blood vessels to widen. This sudden drop in heart rate and blood pressure temporarily reduces blood flow to the brain, leading to dizziness, near-fainting, or loss of consciousness.

   

• Cardiac Syncope occurs when fainting is caused by an underlying heart condition, such as a dangerous arrhythmia or a structural heart abnormality. In people with PLN, this is the most concerning type of syncope because ventricular tachycardia, ventricular fibrillation, or severe conduction abnormalities can temporarily prevent the heart from pumping enough blood to the brain. Cardiac syncope often occurs suddenly with little or no warning and may be accompanied by palpitations, chest pain, shortness of breath, or occur during physical activity or while lying down. In individuals with PLN R14del, cardiac syncope is particularly concerning because it may result from life-threatening ventricular arrhythmias such as ventricular tachycardia or ventricular fibrillation. Consciousness usually returns within seconds to a few minutes once normal blood flow is restored, but any suspected cardiac syncope requires immediate medical evaluation, as it may be a warning sign of sudden cardiac arrest. Immediate medical evaluation is essential

• Orthostatic Syncope (Orthostatic Hypotension) occurs when blood pressure drops significantly upon standing from a sitting or lying position. It may result from dehydration, certain medications (including some heart failure medications), prolonged bed rest, or disorders affecting the autonomic nervous system. Symptoms typically include lightheadedness, dizziness, blurred vision, weakness, or feeling faint shortly after standing. Most people recover within a few minutes after sitting or lying down, allowing blood pressure to return to normal, although some may continue to feel tired or unsteady for a short period afterward.

• Situational Syncope is a type of reflex syncope that occurs during specific activities that temporarily stimulate the Vagus nerve and lower blood pressure. Common triggers include coughing, swallowing, urinating, having a bowel movement, or laughing. These episodes are generally benign but should still be discussed with your healthcare provider. Symptoms are similar to vasovagal syncope and may include dizziness, sweating, nausea, and blurred vision before a brief loss of consciousness. Recovery is typically rapid, with most people returning to their normal state within 5 to 30 minutes after the triggering event has passed. 

• Neurologic Syncope is a less commonly, fainting may be related to neurological conditions such as severe headache, weakness, difficulty speaking, vision changes, confusion, or seizure-like activity before or after fainting. Recovery time varies depending on the underlying neurological condition, and some individuals may experience prolonged confusion or neurological symptoms that require urgent evaluation by a healthcare provider. Although these episodes are not caused by heart disease, they may require evaluation by a neurologist to determine the underlying cause.

• Neurologist: Although many episodes of syncope originate from the cardiovascular system, a neurologist may become involved if the cause is unclear or if symptoms suggest a neurological disorder. Conditions such as seizures, migraine disorders, autonomic nervous system disorders, or certain diseases affecting the brain can sometimes mimic fainting or cause similar symptoms. A neurologist may perform additional testing, including brain imaging, electroencephalography (EEG), or autonomic function testing, to determine whether the nervous system is contributing to your symptoms. They may recommend a tilt table test. During this test, you are secured to a specialized table that slowly changes from lying flat to an upright position while your heart rate, blood pressure, and symptoms are continuously monitored. The goal is to determine whether changes in body position trigger abnormal drops in blood pressure or heart rate that could explain your symptoms. The test may reproduce dizziness, presyncope, or fainting in a controlled medical environment and can help distinguish vasovagal syncope from other causes.

• Unexplained (Unknown Cause) Syncope is sometimes the cause of fainting cannot be identified after an initial evaluation. In individuals with inherited cardiomyopathies like PLN R14del, unexplained syncope warrants further investigation because it may be the first sign of an underlying arrhythmia. Your cardiologist may recommend additional testing, such as an electrocardiogram (ECG), Holter monitor, event monitor, implantable loop recorder, echocardiogram, cardiac MRI, exercise stress test, or electrophysiology study, depending on your symptoms and medical history.

• Increased Urine Output After An Episode can occur because hormones released during stress and changes in blood pressure temporarily alter how the kidneys regulate fluid balance. In addition, lying flat after an episode increases blood flow to the kidneys, which may stimulate increased urine production. While this can occur after benign vasovagal episodes, it may also be seen following certain cardiac arrhythmias. If you consistently experience significant increases in urine output following these events, mention this to your cardiologist, as it may provide an additional clue about the underlying cause.

If you experience unexplained fainting, almost fainting, especially if it occurs during exercise, is associated with palpitations or chest pain, or if you have a known diagnosis of PLN, you should seek immediate medical evaluation. While vasovagal and orthostatic syncope are common and often benign in the general population, any episode of unexplained fainting in someone with PLN warrants prompt medical evaluation. Because PLN is associated with an increased risk of life-threatening ventricular arrhythmias and sudden cardiac arrest, it is important to determine whether the episode was caused by a heart rhythm abnormality or another condition so that appropriate treatment and monitoring can be initiated. Your healthcare provider may recommend additional testing, such as an electrocardiogram (ECG), Holter monitor, cardiac MRI, or an evaluation by an electrophysiologist (EP) to determine the underlying cause.

Ventricle

One of the heart’s two lower pumping chambers. The right ventricle pumps blood to the lungs, while the left ventricle pumps oxygen-rich blood to the rest of the body.

Ventricular Arrhythmia

An abnormal heart rhythm that begins in the heart’s lower chambers, or ventricles. Some ventricular arrhythmias are brief and stop on their own, while others can become dangerous and interfere with the heart’s ability to pump blood.

Ventricular Tachycardia (VT or V-Tach)

A fast, potentially life-threatening heart rhythm originating in the ventricles. Sustained VT is a major cause of sudden cardiac arrest in PLN-related cardiomyopathy.

• Non-sustained Ventricular Tachycardia (NSVT): A short episode of an abnormally fast heart rhythm that begins in the heart’s lower chambers, called the ventricles. It starts and stops on its own and lasts less than 30 seconds. NSVT may not cause symptoms, or it may cause palpitations, dizziness, or lightheadedness. Its significance depends on the person’s overall heart condition.