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Glossary

Terms

A

Alveoli
The smallest lung units that include thin-walled air sacs directly linked with a network of small blood vessels (capillaries) where gas exchange occurs
Angina
Chest pain that is caused by parts of the heart not getting enough blood; usually the result of atherosclerosis of the coronary arteries.
Anticoagulants
Medications that thin the blood make the formation of blood clots less likely.
Anticoagulation
The act of receiving therapy with anticoagulants
Aorta
The largest artery in the body; carries all the oxygenated blood pumped out by the left ventricle to the rest of the body via a branching network of smaller arteries
Aortic valve
A valve in the heart that separates the left ventricle from the aorta preventing blood from flowing backwards into the ventricle.
Arginine
An essential amino acid whose natural breakdown and metabolism generates the potent vasodilator nitric oxide
Asthma
A disease in which the muscles surrounding the airways of the lungs spasm and result in reversible narrowing of the airways, making it difficult to exhale.
Atrium
The two smaller chambers (one on each side) of the heart; the right atrium accepts blood from the veins throughout the body and the left atrium accepts freshly oxygenated blood from the lungs

B

BNP (b-type or brain natriuretic peptide)
A protein that is released by the muscle tissue of the heart, particularly the ventricles; the amount that is released increases as the heart is stretched or strained.
Bronchi
Branching airways in the lungs that carry air from the trachea to the alveoli
Bubble study
A specialized echocardiogram that looks for holes between the right and left sides of the heart by injecting bubbles (agitated saline) into the bloodstream and watching to see if they cross from the one side of the heart to the other

C

Calcium channel blocker
A type of medication that is a vasodilator and is occasionally used to treat PAH (e.g. amlodipine); also, often used for patients who have systemic hypertension
Capillaries
The smallest type of blood vessel, located throughout the body including lungs; the place where oxygen, nutrients, and waste products are exchanged from bloodstream to cells and vice versa.
Carbon Dioxide
A gaseous molecule that is one of the waste products generated by the cells of the body.
Cardiac output
The amount of blood (measured in liters per minute) being pumped out by the heart.
Cardiologist
A doctor who is specially trained in diseases of the heart and blood vessels.
Central venous catheter
An intravenous line that is placed in one of the larger veins of your body (usually in the chest) to deliver medications
Cirrhosis
End-stage liver disease due to scarring; often caused by alcohol or viral hepatitis over many years
Congenital heart defects
A defect in the structure of the heart that is present at birth
Congestive heart failure
A disease in which the heart is stiff or does not pump adequately causing a back up of blood and fluid.
Coronary arteries
The blood vessels that supply oxygenated blood to the heart itself; there are three main coronary arteries.
Coronary artery disease
Narrowing of the coronary arteries due to atherosclerosis (build up of cholesterol plaques in the walls of the arteries).
CT Scan
A specialized X-ray machine that can provide detailed images of internal organs including the lungs and their blood vessels.

D

Diaphragm
A muscle that sits below the lungs; when it contracts it helps the lungs expand and take a breath in
Diastole
The period of time when the heart is relaxing, filling with blood and getting ready to contract again
Diastolic blood pressure
(the bottom number of the reading) is measured during diastole.
Diffusing capacity (also known as DLCO)
One of the PFTs which measures how well oxygen and carbon dioxide transfer from the air in your lungs into the bloodstream and vice versa.
Diffusion impairment
A characteristic of gas exchange in PAH in which the movement of oxygen from alveoli to capillaries is reduced
Diuretics
Medications used to rid the body of excess fluid
Dyspnea
Shortness of breath, or any uncomfortable sensation of breathings; typically worsens with exertion

E

Echocardiogram
An image obtained by ultrasound (a machine that creates an image from sound waves bouncing off an object) of the heart that provides information about structure, blood flow, contractility (‘squeeze’), and allows estimation of the blood pressure in the pulmonary arteries.
Edema
Swelling caused by fluid build-up and fluid leaking out of blood vessels into surrounding soft tissues; usually occurs in areas that are dependent, such as the legs.
Emphysema
A lung disease usually caused by smoking in which alveoli are lost or damaged, making gas exchange and breathing more difficult
Endothelial cells
Type of cells that line all blood vessels including pulmonary arteries. Transaminitis: an elevation in liver enzymes (measured by a blood test) that indicates irritation, inflammation, or damage to the liver
Endothelin
A very potent vasoconstrictor found in the blood and lung tissue both naturally and in disease states
Endothelin Receptor Antagonists
A class of oral medications that act primarily as vasodilators, and which are used to treat PAH. There are two types of endothelin receptors and medications may block both of these or just one type preferentially.
Exercise oximetry
Measurement of the oxygen saturation in blood during exercise

F

Femoral vein
A large vein in the groin and leg that carries blood from the legs back towards the heart and can be used in right heart catheterization
Functional Class
A four-tiered system that doctors use for describing your overall ability to do activities of daily living.

G

H

Half-life
The period of time in takes for half of any medication to be metabolized by the body; used to measure how long a medication's effects will last and thus how frequently it must be dosed
Heart
The main organ of the circulatory system that has the function of receiving blood from and pumping blood to the rest of the body
Heart attack
Also known as a myocardial infarction (MI); a sudden event when part of the heart is deprived of blood, usually due to a blockage in one of the coronary arteries, resulting in damage to that part of the heart.
Hepatitis
Inflammation of the liver, most often caused by infection from a hepatitis virus (e.g. hepatitis A,B,C)
Hypertension
High blood pressure
Hypoxic vasoconstriction
A characteristic of the pulmonary arteries by which they constrict during periods of low oxygen concentration

I

Inferior vena cava
One of the largest veins in the body, located in the chest; all blood in the lower body (below the heart) travels through this vein which then empties into the right atrium.
INR (or pro-thrombin time)
A blood test that measures how well your blood clots; used to adjust the dose of an anti-coagulant (blood thinner) called warfarin® (coumadin)
Internal jugular vein
A large vein in the neck that carries blood from the head back to the heart and is often used in right heart catheterization

J

K

L

Lungs
The main organs of the respiratory system that have the function of transporting oxygen from the air into the blood and removing carbon dioxide from the blood; located in the chest, one on the left and one on the right.

M

Mean arterial pressure
An average of the systolic and diastolic blood pressures (mean arterial pressure = 2/3 diastolic pressure + 1/3 systolic pressure).
Metered-dose inhalers (MDIs)
Devices that deliver medications into the lungs in the form of a powder or liquid spray
Mitral valve
A valve in the heart that separates the left atrium from the left ventricle preventing blood from flowing from the ventricle backwards into the atrium

N

Nebulizer
A device that uses pressurized air to volatize (turn into mist) a liquid medication that can then be inhaled.
Nitric oxide
A very potent vasodilator found in the blood and in lung tissues; can be used diagnostically during cardiac catheterization as an inhaled agent to test for acute vasodilatation or ‘vasoreactivity’.

O

Obstructive sleep apnea
A disorder in which the upper airway collapses or becomes too lax during sleep causing obstruction of the air passages and cessation of airflow to the lungs.
Oxygen
A gaseous molecule found in the air that serves as the fuel for all the cells in the body.

P

Phosphodiesterase inhibitors
A class of medications used to treat PAH that act as vasodilators
Pneumonia
An infection in the lung, typically causing fever, cough, and phlegm
Polysomnography
Also known as a sleep test; a test during which various parameters such as oxygenation, breathing, heart rhythm, brain waves, blood pressure are measured while you sleep.
Prostacyclin
A group of molecules naturally found in the body with various functions including vasodilation, inhibition of platelet aggregation and smooth muscle proliferation; synthetic prostacyclins are used to treat PAH.
Prostacyclin analogue
A synthetic chemical that acts in the same way that natural prostacyclins do.
Pulmonary arterial pressure
The blood pressure in your pulmonary arteries
Pulmonary arteries and veins
Blood vessels in the lungs that carry blood to (arteries) and away (veins) from the lungs
Pulmonary embolus
(pl. = emboli) a blood clot in one or more pulmonary arteries that arises somewhere else in the body and travels to the lungs; usually forms in the deep veins of the legs and travels up to the pulmonary arteries
Pulmonary function tests (PFTs)
A series of breathing tests that allow measurement of your lung function, including lung capacity, how fast you can expel air from your lungs, and how well your lungs exchange gases.
Pulmonary hypertension
Elevated blood pressure in the pulmonary arteries
Pulmonary valve
A valve in the heart that separates the right ventricle from the pulmonary arteries preventing blood from flowing backwards into the right ventricle
Pulmonologist
A doctor who is specially trained in diseases of the lungs and breathing

Q

R

Red blood cell
A type of cell in your body found in the blood whose function it is to carry oxygen to all the tissues of the body
Resistance
The opposing force to the flow of a fluid, such as blood
Right heart (cardiac) catheterization
A procedure during which a catheter (small flexible tube) is advanced from a vein in you arm or leg to the right side of the heart and into the pulmonary arteries in order to measure pressure

S

Saturation
A measure (in percent) of how close to full your red blood cells are with respect to their oxygen-carrying capacity.
Spirometry
A measurement of how fast you can expel the air in your lungs; usually a part of PFTs.
Subclavian vein
A large vein in the upper chest (between the shoulder and neck) that carries blood back to the heart and is often used in right heart catheterization or as a site for a long-term indwelling catheter through which medication may be infused.
Superior vena cava
One of the largest veins in the body, located in the chest; all blood in the upper body (above the heart) travels through this vein which then empties into the right atrium.
Systemic blood pressure
The blood pressure in the main arteries of your body that run from the left side of your heart to the rest of your body (arms, legs, intestines, kidneys,brain, etc
Systole
The period of time when the heart is contracting and pumping blood to the lungs and the rest of the body
Systolic blood pressure
(the top number of the reading) is measured during systole

T

Thromboemboli
Blood clots that travel from the location they originally formed to another area of the body, i.e. clots in the legs that travel to the lungs
Thrombus (thrombi)
Blood clots
Trachea
Also known as the "windpipe"; a tube-like structure that carries air from the mouth to the lungs
Tricuspid valve
A valve in the heart that separates the right atrium from the right ventricle preventing blood from flowing from the ventricle backwards into the atrium

U

V

V-Q (ventilation-perfusion) scan
A nuclear imaging study that looks at how well areas of the lungs that have air delivery (ventilation) are receiving blood flow (perfusion); usually used to diagnosed pulmonary emboli that cause decreased perfusion
Vasodilation
Widening or dilation of blood vessels.
Vasodilator
A chemical (natural or synthetic) that dilates blood vessels
Ventricle
The two larger chambers (one on each side) of the heart; the right ventricle pumps blood to the lungs for oxygenation and the left ventricle pumps freshly oxygenated blood to the rest of the body.
Vitamin K
A natural vitamin that is found in green leafy vegetables; it counteracts the blood thinning effects of warfarin®.

W

X

Y

Z