ACE-I (angiotensin-converting enzyme) inhibitor
A medication that expands blood vessels, given to make it easier for the heart to pump blood forward to the body; also used to lower blood pressure.

Acquired Heart Disease
Heart disease that develops sometime during childhood as a result of an illness such as Kawasaki disease, rheumatic fever or infectious endocarditis.

Adverse event /effect
Any undesired event or effect that may be seen suddenly or develop during the time that a person is in a study. Examples may include headache, nausea, hair loss, skin irritation, or other physical problems. While all adverse events are reported during a study, they may not be related in any way to the treatment or medicine being studied. Examples may include broken bones from an accident, respiratory infections or other childhood illnesses like chickenpox.

An out-pouching or balloon in the wall of an artery or vein into which blood may flow.

The large artery that receives blood from the heart’s left ventricle and distributes it to the body.

Aortic Root Z-Score
The size of the aorta is measured in a way that will adjust for body size and age.

Aortic Valve
The heart valve between the left ventricle and the aorta.

Child’s agreement to participate in research (not just a failure to object) which goes together with the parents consent.

A complete failure of development of a structure normally present and open at birth, as in mitral atresia.

Atrioventricular Septal Defect (AVSD)
A congenital heart defect involving a hole between the upper receiving chambers of the heart (the atria) and the lower pumping chambers (the ventricles) with abnormal mitral and/or tricuspid valves.

Cardiac Catherization
The process of examining the heart by introducing a thin tube (catheter) into a vein or artery and passing it into the heart.

Cardiac Magnetic Resonance Imaging (MRI)
A painless test that allows different tissues in the body to take on different appearances to determine if something seen is normal or not. MRI systems can also image flowing blood in nearly any part of the body which makes this a good way to see the heart and blood vessels in the body.

Chronic Illness
A disease that is long-lasting or never goes away.

Clinical Study / Trial
A research plan that will answer questions about medicines or new therapies. Clinical trials (also called medical research and research studies) are used to determine if new medicines or treatments are both safe and effective. Carefully conducted trials are the fastest and safest way to find treatments that work in people.

The ethical principle or legal right that requires a health professional to keep information relating to a patient secret, unless the patient gives consent to disclose.

Congenital Heart Defect
A heart defect that is present at birth.

Consent Form
A document that describes the rights of study participants, and includes details about the study, such as its purpose, how long it will last, required procedures, and people to contact. Risks and potential benefits are explained in the informed consent document. The participant then decides whether or not to sign the document. Informed consent is not a contract and the participant may withdraw from the study at any time.

Coronary Artery Aneurysm
A thin, weakened area in the arteries that provide blood to the heart muscle.

Data and Safety Monitoring Board (DSMB)
An independent group composed of doctors, ethicists, statisticians, lay persons and other experts whose responsibility it is to monitor the safety of patients in a study.

Dilated Cardiomyopathy
A disease of the heart muscle that can cause the heart to be enlarged and to lose its pumping strength.

A test that uses sound waves to make a moving picture of the heart, The sound waves are not felt by the person having the test and are not known to be harmful. The test does not hurt, but small children may be afraid of the room, the machine and the new people performing the test.

Electrocardiogram (EKG)
A graphic record of electrical impulses produced by the heart.

Exercise Testing
A study of how much exercise an individual can do compared to others of the same age and size with normal hearts; the test is done using either a treadmill or a stationary bicycle, while the EKG, blood pressure, and breathing are monitored.

Fontan Procedure
The final stage in a series of surgical repairs for children with single ventricle physiology or hypoplastic left heart syndrome.

Medication used to provide antibodies and reduce inflammation.

Genetic Evaluation
An evaluation by a genetics counselor where family and medical history are reviewed, a physical examination is performed, and medical tests may be ordered to evaluate for a possible diagnosis.

Ghent Criteria
A set of rules for findings and clinical observations that lead to a diagnosis of Marfan syndrome (MFS) and help doctors to tell the difference between individuals with MFS and those with other types of connective tissue disorders.

Holter Monitor
A Holter monitor is a machine that continuously records your heart’s activity. The monitor is usually worn for 24 hours during normal activity which you carry in a pocket or small pouch worn around your neck or waist. Small patches are stuck onto your chest and attached to the monitor which is battery operated.

Hypoplastic Left Heart Syndrome
A congenital heart defect in which the left side of the heart is poorly developed, resulting in a small mitral valve, left ventricle, and aorta. May also be called single ventricle defect.

Informed Consent
The process of understanding the key facts about a clinical trial before deciding whether or not to participate.

Institutional Review Board (IRB) or Research Ethics Board (REB)
A board, committee, or other group that is given responsibility by a hospital to review and approve research involving people. The primary purpose of such review is to make sure that the rights and welfare of subjects are protected.

Kawasaki Disease
An illness that involves the skin, mouth, and lymph nodes, and typically affects children who are under the age of 5. The cause of Kawasaki Disease is unknown. Symptoms include fever that is higher than 104 degrees, severe redness in the eyes, a rash on the child’s stomach, chest, and genitals, red, dry, cracked lips, swollen tongue with a white coating and big red bumps, sore, irritated throat, swollen palms of the hands and soles of the feet with a purple-red color and swollen lymph nodes.

MBT Shunt
A connection between the aorta (major blood vessel that brings blood from the heart to the body) and the pulmonary (lung) arteries.

Mitral Regurgitation
An abnormality of the valve between the left atrium and left ventricle of the heart that allows backward flow of blood from the left ventricle into the left atrium.

National Heart, Lung and Blood Institute (NHLBI)
One institute of the National Institutes of Health that conducts and supports medical and behavioral research.

National Institutes of Health (NIH)
A Federal agency whose mission is to improve the health of the people of the United States. It is divided into 24 institutes and research centers that fund research, conduct studies, and fund multicenter national studies.

Neurodevelopmental Exam
A medical and behavioral exam that will look at physical development and motor skills, thinking and learning cognitive development. The exam is given by a neurodevelopmental specialist and may include parent and child questionnaires.

Norwood Procedure
The first stage to repair a single ventricle heart. It involves 1) enlarging the aorta (major blood vessel that brings blood from the heart to the body), 2) opening the wall between the two upper chambers of the heart (atria) and 3) creating a shunt (small connection) to deliver blood from the heart to the lung arteries so that blood can get to the lungs where it receives oxygen.

Observational Study
A study without randomization or treatment in which subject information is collected to categorize and quantify observations.

An inactive pill, liquid, or powder that has no active medicine in it.

When something comes early. Premature birth is a birth that happens before 9 months; premature heart beat is a beat or contraction of the heart that happens before it is suppose to happen.

Principal / Study Investigator
A medical researcher in charge of carrying out a clinical trial.

Randomized Clinical Trial
A research study in which participants are randomly assigned (i.e., similar to flipping a coin) to one of two or more treatment groups.

Randomly Assigned/Randomized
A method based on chance (like flipping a coin or pulling a number out of a hat) to assign each study participant to one or more groups. Since researchers do not know which treatment is better, any one of the treatments chosen could be of benefit to the participant.

Research Coordinator
A site administrator for a clinical study, also called research coordinator, study or healthcare coordinator, data manager, research nurse or protocol nurse.

Research Team
A group of doctors, nurses, research assistants and others who are involved with a clinical study.

Reye’s Syndrome
A disease which affects all organs of the body and typically occurs when a person is beginning to recover from a viral illness such as flu, cold, or chicken pox.  The chances of developing Reye’s Syndrome can be reduced by not giving aspirin to children for relief of discomfort or fever.

RV-to-PA Shunt
A connection between the right ventricle (lower pumping chamber of the heart) to the pulmonary (lung) arteries.

Shaking, twitching, staring or loss of consciousness caused by electrical activity in the brain.

A connector or tube to allow blood flow between two locations.

Side effect
Any unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a research product, whether or not it is related to the product and even if it is beneficial. See Adverse event.

Single Ventricle Defect or Hypoplastic left heart syndrome
A congenital heart defect in which the left side of the heart is poorly developed, resulting in a small mitral valve, left ventricle, and aorta which cannot function normally.

Steering Committee
A PHN group whose primary responsibility it is to select, design and conduct studies. Membership includes the Principle Investigator from each participating hospital and the data coordinating center, Network Chair and a NHLBI representative.

Narrowing or obstruction of a valve or opening, which may be present from birth (as in mitral stenosis).

Study Protocol
A study plan that is carefully designed to make sure the participants are safe and to answer specific research questions. A protocol describes what types of people may participate, the schedule of tests, procedures, medications, and the length of the study.

A living individual about whom an investigator obtains data or identifiable private information when conducting research. 

A lip of tissue that acts like a door opening and closing helping the blood to flow in one direction at the right time. The heart and other blood vessels have valves.

One of the two lower pumping chambers of the heart. The left ventricle pumps to the body, the right ventricle to the lungs.