Prevention of Fungal Infections

Slideshow transcript

Slide 1: PREVENTION OF FUNGAL INFECTIONS Gamini Kumarasinghe Division of Microbiology National University Hospital, Singapore 1

Slide 2: Fungi range in size C. albicans Amanita muscaria Polyporus sulphureus chlamydospores Mycelia inside potato Black bread mold 2 Mycelia on various foods

Slide 3: Fungal Habitats Found in virtually every habitat on the earth where organic materials exist, including the Antartica • salt, sugar etc • leather, wax, jet fuel, plastics etc • thermal pools, volcanic craters 3

Slide 4: Prevention Of Fungal Infections • Advancements in modern medicine has left many individuals with impaired immune systems • These individuals are the most vulnerable to the fungal diseases 4

Slide 5: Prevention Of Fungal Infections The usual reservoir - not an infected human or animal - a site in nature where the fungus is growing as a saprophyte Chung & Bennett, 1992 5

Slide 6: Prevention Of Fungal Infections Because human mycoses are poorly communicable from person to person, mycoses are often endemic but rarely epidemic. Chung & Bennett, 1992 6

Slide 7: Prevention Of Fungal Infections mopping the floor e.g. diving boards & floor mats periodically with a fungicidal solution 7

Slide 8: ISOLATION PRECAUTIONS ? 8

Slide 9: Isolation Precautions Respiratory isolation - not indicated even when the patient in the adjacent bed is immunosuppressed Outside of neonatal candidiasis, transmission of a deep mycosis has been extraordinarily rare (C & B; Garner, 1996) 9

Slide 10: INFECTION IN THE HOSPITAL Immuno-compromised patients 10

Slide 11: Infection In The Hospital Aspergillosis 11

Slide 12: Infection In The Hospital Aspergillosis Patients susceptible to invasive aspergillosis are particularly congregated in • oncology • transplantation • intensive care units 12

Slide 13: Nosocomial Aspergillosis “safety levels” for bio-aerosols ? • Rural outdoor air – 10,000 CFU/cm • Threshold limit in indoor environment unknown Positive correlation – increased spore count & IA (Iwen et al, 1994; Hay et al, 1995) 13

Slide 14: Protective Isolation Positive Pressure Ventilation (PPV) • sealed room • with an anteroom • air-floor at least 12 ACH • HEPA filter (99.97% efficient at 0.3 µg particles) (ASHRAE, 1998; Humphreys, 2003) 14

Slide 15: Protective Isolation Laminar air-flow (LAF) • much greater ACH • expensive • noise • drafts Uncomfortable to the patient (ASHRAE, 1998; Humphreys, 2003) 15

Slide 16: Positive Pressure Ventilation Room Anteroom Patient’s Room Exhaust Bed Adapted from HPAC, 2000 PPV : 12 ACH LAF : 400 ACH 16

Slide 17: Infection In The Hospital Aspergillosis Keeping patients in such special rooms - considerable cost - nursing care, medical attention - emotional stress on the patient 17

Slide 18: Nosocomial Aspergillosis Most institutions rely on PPV filtration & not on LAF Important risk factor • immunosuppressive condition High risk patients may develop IA even with low spore count (Hay et al, 1995) 18

Slide 19: Protective Isolation HEPA filters Haematological malignancies - protective for highly IC patients - effective at controlling outbreaks due to Aspergillus conidia (Hahn et al., 2002) 19

Slide 20: Protective Isolation HEPA filters Bone marrow transplant recipients - tenfold greater incidence than other IC patients - risk could be eliminated by using HEPA with LAF (Sheretz et al., 1987) 20

Slide 21: Protective Isolation Portable HEPA filters ? 21

Slide 22: Protective Isolation Portable HEPA filters - costly preventive strategy of questionable value1 - under field conditions portable units not recommended2 1. Mantadakis & Samonis, 2006 2. Engelhart et al., 2003 22

Slide 23: Nosocomial infections: other moulds Fusarium, Trichosporon spp., dematiaceous moulds, Zygomycetes etc may affect immunocompromised patients (Walter EA, 1995) 23

Slide 24: Fungal Infections “other moulds” IC individuals risk infections by more than 270 species • contaminated skin lotions, twigs, medications etc • gain access: through GI tract • normally a sign of contamination (but in neutropaenic might indicate disseminated disease) 24 Perfect JR, 2005

Slide 25: Fungal Infections IC individuals risk infections by more than 270 species Good housekeeping 25 Perfect JR, 2005

Slide 26: Infection In The Hospital Candidiasis 26

Slide 27: Infection In The Hospital Candidiasis The usual reservoir is the patient's own body 27

Slide 28: Infection In The Hospital Candidiasis Patients with severe and prolonged neutropenia Prone to develop disseminated candidiasis from numerous small ulcers caused by Candida species in the stomach, oesophagus, and intestine 28

Slide 29: Infection In The Hospital Prevention of candidiasis Despite massive oral doses of nystatin, to reduce Candida in stools prevention of disseminated candidiasis has not been convincingly demonstrated 29

Slide 30: Infection In The Hospital Topical / Non-absorbable antifungal agents • clotrimazole • nystatin • amphotericin B - decrease colonizing burden - mucosal manifestations However, does not reduce invasive candidiasis or mould infection (Tollemar, 1997; Boeckh & Marr, 2001) 30

Slide 31: Infection In The Hospital Candidiasis in Neonatal Units • Low birth weight more susceptible • blood stream infection following IV catheters 31

Slide 32: Prophylaxis Candidiasis in Neonatal Units • candidaemia in low birth weight – high mortality • preliminary data – fluconazole reduces infections • this practice is not used widely • criteria for initiation prophylaxis is unknown Aseptic techniques, care of umbilical catheters Burwell, 2006 32

Slide 33: INFECTION IN THE LABORATORY 33

Slide 34: Infection In The Laboratory • Ubiquitous fungi, such as Candida and Aspergillus, can be handled with BSL 1 precautions • Standard microbiologic technique is all that is required 34

Slide 35: Infection In The Laboratory H. capsulatum or C. immitis • for opening culture dishes • pipetting, vortexing, • any other activity that might generate an aerosol • handling ‘mould forms’ Class 1 or class 2 biologic safety cabinet 35

Slide 36: Infection In The Laboratory • Most other procedures with pathogenic fungi can be done at biosafety level 2 • This includes processing clinical specimens and working with the ‘yeast form’ of H. capsulatum or spherules of C. immitis 36

Slide 37: Classification of Microorganisms • Risk group 1 ubiquitous • Risk group 2 hepatitis B, HIV • Risk group 3 TB, Fungi* • Risk group 4 African h’gic fevers – aerosol generating procedures* – ‘mould forms’ 37

Slide 38: PRECAUTIONS WITH INFECTED LABORATORY ANIMALS 38

Slide 39: Precautions With Infected Laboratory Animals • Biosafety level 2 precautions are adequate for all mycoses • Urine of animals may contain C neoformans, H capsulatum & C immitis & contaminate cage bedding • Animal bedding contaminated with the tissue forms might convert and grow the mould during prolonged storage 39

Slide 40: Environmental control 40

Slide 41: Environmental control Yeasts • Candida is present in the subject's endogenous reservoir (Odds, 1998) • However, exogenous sources such as another person, food, intravenous catheters, and parenteral fluids—have also been reported (Meunier, 1987) • Reduction in risk factors, aseptic practices & reducing Candida colonization 41

Slide 42: Environmental control Aspergillus spp. & other molds Outbreaks of infections after construction work in hospitals (Bodey & Vartivarian, 1989) 42

Slide 43: • Construction & renovation associated with IA (Weems et al, 1987) • HEPA significantly reduces the incidence of lA (Humphreys, 2004) • Enhanced cleaning & the sealing of windows • the use of prophylactic anti-fungal agents ??? 43

Slide 44: Prevention Of Fungal Infections Endemic areas of histoplasmosis / coccidiomycosis Preventing inhalation of infected dust - more difficult - control measures appear prudent around desert military training areas, airports and helicopter landing areas, construction sites etc e.g. water sprays, disinfectants (DHHS, 1997) 44

Slide 45: Environmental control • Cryptococcosis is an exogenous infection • usually acquired prior to hospitalization by inhalation of fungal spores found in soil, vegetable matter, and bird excrement. 45

Slide 46: Environmental control • proper cooking of food • avoidance of raw vegetables & pepper • no potted plants or flowers should be allowed on the ward (Tollemar, 1997) 46

Slide 47: Fungi in the environment One year old study in a major tertiary care hospital About 200 bone marrow and organ transplants / yr Dept of Environmental and Occupational Health Science, University of Illinois at Chicago Curtis et al, 2005 47

Slide 48: Fungi in the environment One year old study: monitor fungi in the hospital • extensive indoor renovations • several large demolition & building projects within 1 km Curtis et al, 2005 48

Slide 49: Fungi in the environment One year old study • Aspergillus propagules in all parts of the hospital • Aspergillus concentrations higher indoors cf to outside • Total fungi were significantly higher outside Therefore, infiltration of outside air cannot be the primary mechanism for producing airborne aspergillus levels Curtis et al, 2005 49

Slide 50: Fungi in the environment One year old study Aspergillus sources in the hospital • dust from duct cleaning • renovation • sites of water damage • moisture condensation Curtis et al, 2005 50

Slide 51: Fungi in the environment One year old study Approaches to controlling aspergillus infections in hospitals • moisture / water control • HEPA filters • sealed positive pressure rooms • environmental monitoring of aspergillus Curtis et al, 2005 51

Slide 52: Potted plants & Flowers • differences in opinion • current guidance, in favour of their removal from clinical areas • not in the vicinity of IC patients CDC, MMWR 2000;49(RR10):1-128 52

Slide 53: Fungal Infection Prevention Routine measures – not the ideal solution 53

Slide 54: Fungal Infection Prevention • Environmental fungi - preventing exposure, not effective • Endogenous flora - difficult • Improving host defences - not always possible 54

Slide 55: Prevention Resort to Antifungal Agents • Prophylactic • Empirical & • Pre-emptive therapy 55

Slide 56: Prophylaxis Antimicrobials administered to patients at high risk of developing the disease, who are not infected and not manifesting symptomatic disease. Goodman et al., 1992 56

Slide 57: Empiric therapy • commencement of Rx at the first clinical suspicion • still results in about 10% break through infections De Pauw, 2005 57

Slide 58: Emperic therapy Toxicity & cost are major shortcomings of such therapy Hence, “preemptive” approach Maertens clin inf dis 2005 Nov 1 58

Slide 59: Preemptive Therapy 59

Slide 60: Preemptive Therapy The administration of antimicrobials to patients already infected, but who do not yet manifest symptomatic disease in whom there are markers of pathogen invasion Synonymous with secondary prophylaxis or preventive therapy Singh N., 2001 60

Slide 61: Diagnosis of fungal infections • conventional microbiological • histological • radiological techniques were the cornerstone of diagnosis 61

Slide 62: Diagnosis of fungal infections Limited impact on clinical decision making • too insensitive • time consuming • lacked general accessibility So P-E therapy depends on microbiological markers i.e. non-culture techniques Hope et al., 2005 62

Slide 63: Microbiologic markers Non culture based assays 63

Slide 64: Preemptive therapy Non culture based assays • galactomannan • beta-D-glucon (accuracy, role in diagnosis remains unclear, Wheat 2006) • fungal DNA by PCR (validation & standardization needed) Maertens et al, 2006 64

Slide 65: Preemptive therapy Galactomannan • multicentre study; 61% sensitivity & 93% specificity (Pfeiffer et al., 2005) • clinical issues unanswered does the assay correlates with fungal burden ? impact of antifungals on test performance ? cut-off value ? false-positives and false-negative values etc etc ? In conjunction with imaging techniques Maertens et al., December 2006 65

Slide 66: preemptive therapy Galactomannan and computed tomography • Galactomannan • thoraxic computed tomography scanning • bronchoscopy with lavage Conclusion: Reduce the exposure to expensive and potentially toxic drugs & offer effective antifungal control Failed to detect non-Aspergillus IFI Maertens et al., 2005 66

Slide 67: Candida markers Mannan is a major component of the Candida cell wall Platelia Ag/Ab; Bio-Rad Lab 93% specificity & 80% sensitivity (Sendid et al., 1999 & 2002, Year et al., 2001) 67

Slide 68: PROPHYLAXIS 68

Slide 69: Antifungal prophylaxis Invasive Yeast Infection Oral fluconazole At a dose of 400 mg/day • provides protection against invasive yeasts • if infection occurs despite fluconazole - assume the isolate is resistant - moulds universally resistant Emergence of non-albicans resistant strains C krusei, C glabrata – naturally resistant (MMWR, 2000; Goodman et al, 1992) 69

Slide 70: Antifungal prophylaxis Invasive Mould Infection • regimens studied - moderate dose amphotericin B - low dose amphotericin B - aerosolized amphotericin B - intranasal amphotericin B - lipid formulations of amphotericin B - itraconazole • no regimen shown to be effective Hence, environmental protection strategies Boeckh & Marr, 2001; MMWR 2000; 49:1-125 70

Slide 71: Prophylaxis Solid Organ Transplant (SOT) A more controversial issue - primary antifungal chemoprophylaxis, because only a few trials have been done (Tollemar et al, 1995; Lumbreras, 1996) 71

Slide 72: Pneumocystis jirovecii • Autologous and allogenic transplantation • Prophylaxis with TMP-SMX – negligible rates • Dapsone, atovaquone or inhaled pentamidine 72 (Espinel-Ingroff et al., 1997, 2000)

Slide 73: Pneumocystis jirovecii Adults - ALL - CNS tumours receiving high-dose corticosteroid therapy - patients receiving combination corticosteroid therapy with either myelotoxic agents or fludarabine prophylaxis should be considered (Sullivan et al, 2001) 73

Slide 74: Pneumocystis jirovecii Children acute lymphoblastic leukemia allogeneic BMT SCT recipients - are known high-risk groups that should be offered prophylaxis. Momin & Chandrasekar, 1995: Link et al, 1993 74

Slide 75: New antifungal agents 75

Slide 76: New antifungal agents • Less toxic formulations of amp B • Improved azoles: Itraconazole, Voriconazole Posaconazole • Echinocandin: micafungin Despite these advances, mortality rates for IFI is about 90% Denning et al., 1998 76

Slide 77: Summary and Conclusions 77

Slide 78: Summary of major recommendation for prevention of invasive fungal infection (Sullivan et al, 2001) Rating Type of Prevention Handwashing to prevent spread of exogenous Alll Candida species Fungal surveillance cultures are not indicated in Dll asymptomatic patients Topical antifungal agents are not recommended Dll for prevention of invasive fungal infection Fluconazole (400 mg/day) is recommended to All prevent invasive yeast Patients are to avoid hospital construction or Alll renovation areas 78

Slide 79: Future • Pre-emptive approach for the prevention • Methods to monitor aspergillus in hospitals & other environments - use of ELISA* - DNA hybridization** - PCR** * Arruda et al., 1992 ** Rath & Ansorg, 2000 79

Slide 80: Conclusions • The prevention an important goal of IC patients • Non-culture microbiologic assays • Prophylactic fluconazole at a dose of 400 mg/day decrease both the rate of invasive yeast infection and mortality • Thus far, no prophylactic strategy has been shown to decrease the incidence of invasive mould infection • Enhanced cleaning of the environment 80

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Cardiovascular Glossary

Cardiovascular Glossary
(Nurses Informations)

Abdomen - The area of the body between the bottom of the ribs and the top of the thighs.

Abdominal aorta - The portion of the aorta in the abdomen.

Ablation - Elimination or removal.

ACE (angiotensin-converting enzyme) inhibitor - A medicine that lowers blood pressure by interfering with the breakdown of a protein-like substance involved in blood pressure regulation.

Acetylcholine - A type of chemical (called a neurotransmitter) that transmits messages among nerve cells and muscle cells.

Alveoli - Air sacs in the lungs where oxygen and carbon dioxide are exchanged.

Amiodarone (Cordarone, Pacerone) - A kind of medicine (called an antiarrhythmic) used to treat irregular heart rhythms such as atrial fibrillation and ventricular tachycardia. It works by regulating nerve impulses in your heart. Amiodarone is mainly given to patients who have not responded to other antiarrhythmic medicines.

Aneurysm - A sac-like protrusion from a blood vessel or the heart, resulting from a weakening of the vessel wall or heart muscle.

Angina or angina pectoris - Chest pain that occurs when diseased blood vessels restrict blood flow to the heart.

Angiography - An x-ray technique where dye is injected into the chambers of your heart or the arteries that lead to your heart (the coronary arteries). The test lets doctors measure the blood flow and blood pressure in the heart chambers and see if the coronary arteries are blocked.

Angioplasty - A nonsurgical technique for treating diseased arteries by temporarily inflating a tiny balloon inside an artery.

Angiotensin II receptor blocker - A medicine that lowers blood pressure by blocking the action of angiotensin II, a chemical in the body that causes the blood vessels to tighten (constrict).

Annulus - The ring around a heart valve where the valve leaflet merges with the heart muscle.

Antiarrhythmics - Medicines used to treat patients who have irregular heart rhythms.

Anticoagulant - Any medicine that keeps blood from clotting; a blood thinner.

Antihypertensive - Any medicine or other therapy that lowers blood pressure.

Aorta - The largest artery in the body and the initial vessel to supply blood from the heart.

Aortic valve - The valve that regulates blood flow from the heart into the aorta.

Aphasia - The inability to speak, write, or understand spoken or written language because of brain injury or disease.

Arrhythmia (or dysrhythmia) - An abnormal heartbeat.

Arrhythmogenic right ventricular dysplasia (ARVD) - ARVD is a type of cardiomyopathy with no known cause. It appears to be a genetic condition (passed down through a family's genes). ARVD causes ventricular arrhythmias. The most common symptoms are heart palpitations, fainting or loss of consciousness (syncope), and, sometimes, sudden death.

Arteriography - A test that is combined with cardiac catheterization to visualize an artery or the arterial system after injection of a contrast dye.

Arterioles - Small, muscular branches of arteries. When they contract, they raise resistance to blood flow, and blood pressure in the arteries increases.

Artery - A vessel that carries oxygen-rich blood to the body.

Arteritis - Inflammation of the arteries.

Arteriosclerosis - A disease process, commonly called "hardening of the arteries", which includes a variety of conditions that cause artery walls to thicken and lose elasticity.

Ascending aorta - The first portion of the aorta, emerging from the heart's left ventricle.

Aspirin - Acetylsalicylic acid; a medicine used to relieve pain, reduce inflammation, and prevent blood clots.

Atherectomy - A nonsurgical technique for treating diseased arteries with a rotating device that cuts or shaves away material that is blocking or narrowing an artery.

Atherosclerosis - A disease process that leads to the buildup of a waxy substance, called plaque, inside blood vessels.

Atrium (right and left) - The two upper or holding chambers of the heart (together referred to as atria).

Atrial flutter - A type of arrhythmia where the upper chambers of the heart (the atria) beat very fast, causing the walls of the lower chambers (the ventricles) to beat inefficiently as well.

Atrial septal defect - See septal defect.

Atrial tachycardia - A type of arrhythmia that begins in the heart's upper chambers (the atria) and causes a very fast heart rate of 160 to 200 beats a minute. A resting heart rate is normally 60 to 100 beats a minute.

Atrioventricular block - An interruption or disturbance of the electrical signal between the heart's upper two chambers (the atria) and lower two chambers (the ventricles).

Atrioventricular (AV) node - A group of cells in the heart located between the upper two chambers (the atria) and the lower two chambers (the ventricles) that regulates the electrical current that passes through it to the ventricles.

Atrium - Either one of the heart's two upper chambers.

Autologous - Relating to self. For example, autologous stem cells are those taken from the patient’s own body.

Autoregulation - When blood flow to an organ stays the same although pressure in the artery that delivers blood to that organ may have changed.
Bacteria - Germs that can lead to disease.

Bacterial endocarditis - A bacterial infection of the lining of the heart's chambers (called the endocardium) or the heart's valves.

Balloon catheter - A long tube-like device with a small balloon on the end that can be threaded through an artery. Used in angioplasty or valvuloplasty.

Balloon valvuloplasty - A procedure to repair a heart valve that is not working properly. A balloon-tipped catheter is threaded through an artery and into the heart. The balloon is inflated to open and separate any narrowed or stiffened flaps (called leaflets) of a valve. The catheter and deflated balloon are removed after the procedure.

Beta-blocker - An antihypertensive medicine that limits the activity of epinephrine, a hormone that increases blood pressure.

Biopsy - The process by which a small sample of tissue is taken for examination.

Blalock-Taussig procedure - A shunt between the subclavian and pulmonary arteries used to increase the supply of oxygen-rich blood in "blue babies" (see below).

Blood clot - A jelly-like mass of blood tissue formed by clotting factors in the blood. Clots stop the flow of blood from an injury. Clots can also form inside an artery when the artery's walls are damaged by atherosclerotic buildup, possibly causing a heart attack or stroke.

Blood pressure - The force or pressure exerted by the heart in pumping blood; the pressure of blood in the arteries.

Blue babies - Babies who have a blue tinge to their skin (cyanosis) resulting from insufficient oxygen in the arterial blood. This condition often indicates a heart defect.

Body mass index (BMI) - A number that doctors use to determine the risk of cardiovascular disease created by a person being overweight. BMI is calculated using a formula of weight in kilograms divided by height in meters squared (BMI =W [kg]/H [m²]). Click here for a BMI calculator.

Bradycardia - Abnormally slow heartbeat.

Bruit - A sound made in the blood vessels resulting from turbulence, perhaps because of a buildup of plaque or damage to the vessels.

Bundle branch block - A condition in which parts of the heart's conduction system are defective and unable to conduct the electrical signal normally, causing an irregular heart rhythm (arrhythmia).

Bypass - Surgery that can improve blood flow to the heart (or other organs and tissues) by providing a new route, or "bypass," around a section of clogged or diseased artery.

Calcium channel blocker (or calcium blocker) - A medicine that lowers blood pressure by regulating calcium-related electrical activity in the heart.

Capillaries - Microscopically small blood vessels between arteries and veins that distribute oxygen-rich blood to the body's tissues.

Cardiac - Pertaining to the heart.

Cardiac arrest - The stopping of the heartbeat, usually because of interference with the electrical signal (often associated with coronary heart disease).

Cardiac catheterization - A procedure that involves inserting a fine, hollow tube (catheter) into an artery, usually in the groin area, and passing the tube into the heart. Often used along with angiography and other procedures, cardiac catheterization has become a primary tool for visualizing the heart and blood vessels and diagnosing and treating heart disease.

Cardiac enzymes - Complex substances capable of speeding up certain biochemical processes in the heart muscle. Abnormal levels of these enzymes signal heart attack.

Cardiac output - The amount of blood the heart pumps through the circulatory system in one minute.

Cardiologist - A doctor who specializes in the study of the heart and its function in health and disease.

Cardiology - The study of the heart and its function in health and disease.

Cardiomyopathy - A disease of the heart muscle that leads to generalized deterioration of the muscle and its pumping ability.

Cardiopulmonary bypass - The process by which a machine is used to do the work of the heart and lungs so the heart can be stopped during surgery.

Cardiopulmonary resuscitation (CPR) - An emergency measure that can maintain a person's breathing and heartbeat. The person who performs CPR actually helps the patient's circulatory system by breathing into the patient's mouth to give them oxygen and by giving chest compressions to circulate the patient's blood.

Cardiovascular (CV) - Pertaining to the heart and blood vessels that make up the circulatory system.

Cardioversion - A technique of applying an electrical shock to the chest to convert an abnormal heartbeat to a normal rhythm.

Carotid artery - A major artery (right and left) in the neck supplying blood to the brain.

Cerebral embolism - A blood clot formed in one part of the body and then carried by the bloodstream to the brain, where it blocks an artery.

Cerebral hemorrhage - Bleeding within the brain resulting from a ruptured blood vessel, aneurysm, or head injury.

Cerebral thrombosis - Formation of a blood clot in an artery that supplies part of the brain.

Cerebrovascular - Pertaining to the blood vessels of the brain.

Cerebrovascular accident - Also called cerebral vascular accident, apoplexy, or stroke. Blood supply to some part of the brain is slowed or stopped, resulting in injury to brain tissue.

Cerebrovascular occlusion - The blocking or closing of a blood vessel in the brain.

Cholesterol - An oily substance that occurs naturally in the body, in animal fats and in dairy products, and that is transported in the blood. Limited amounts are essential for the normal development of cell membranes.

Cineangiography - The technique of using moving pictures to show how a special dye passes through blood vessels, allowing doctors to diagnose diseases of the heart and blood vessels.

Circulatory system - Pertaining to the heart, blood vessels, and circulation of blood.

Claudication - A tiredness or pain in the arms and legs caused by an inadequate supply of oxygen to the muscles, usually due to narrowed arteries.
Collateral circulation - Blood flow through small, nearby vessels in response to blockage of a main blood vessel.

Commissurotomy -A procedure used to widen the opening of a heart valve that has been narrowed by scar tissue. First developed to correct rheumatic heart disease.

Computed tomography (CT or CAT scan) - An x-ray technique that uses a computer to create cross-sectional images of the body.

Conduction system - Special muscle fibers that conduct electrical impulses throughout the heart muscle.

Congenital - Refers to conditions existing at birth.

Congenital heart defects - Malformation of the heart or of its major blood vessels present at birth.

Congestive heart failure - A condition in which the heart cannot pump all the blood returning to it, leading to a backup of blood in the vessels and an accumulation of fluid in the body's tissues, including the lungs.

Coronary arteries - Two arteries arising from the aorta that arch down over the top of the heart and divide into branches. They provide blood to the heart muscle.

Coronary artery bypass (CAB) - Surgical rerouting of blood around a diseased vessel that supplies blood to the heart. Done by grafting either a piece of vein from the leg or the artery from under the breastbone.

Coronary artery disease (CAD) - A narrowing of the arteries that supply blood to the heart. The condition results from a buildup of plaque and greatly increases the risk of a heart attack.

Coronary heart disease - Disease of the heart caused by a buildup of atherosclerotic plaque in the coronary arteries that can lead to angina pectoris or heart attack; a general term.

Coronary occlusion - An obstruction of one of the coronary arteries that hinders blood flow to the heart muscle.

Coronary thrombosis - Formation of a clot in one of the arteries carrying blood to the heart muscle. Also called coronary occlusion.

Cryoablation - The removal of tissue using an instrument called a cold probe.

Cyanosis - Blueness of the skin caused by a lack of oxygen in the blood.

Cyanotic heart disease - A birth defect of the heart that causes oxygen-poor (blue) blood to circulate to the body without first passing through the lungs.

Death rate (age-adjusted) - A death rate that has been standardized for age so different populations can be compared or the same population can be compared over time.

Deep vein thrombosis - A blood clot in a deep vein in the calf.

Defibrillator - A machine that helps restore a normal heart rhythm by delivering an electric shock.

Diabetes (diabetes mellitus) - A disease in which the body doesn't produce or properly use insulin. Insulin is needed to convert sugar and starch into the energy used in daily life.

Diastolic blood pressure - The lowest blood pressure measured in the arteries. It occurs when the heart muscle is relaxed between beats.

Digitalis - A medicine made from the leaves of the foxglove plant. Digitalis is used to treat congestive heart failure (CHF) and heart rhythm problems (arrhythmias). Digitalis can increase blood flow throughout the body and reduce swelling in the hands and ankles.

Dissecting aneurysm - A condition in which the layers of an artery separate or are torn, causing blood to flow between the layers. Dissecting aneurysms usually happen in the aorta, the large vessel that carries blood from the heart to other parts of the body.

Diuretic - A drug that lowers blood pressure by causing fluid loss. Diuretics promote urine production.

Doppler ultrasound - A technology that uses sound waves to assess blood flow within the heart and blood vessels and to identify leaking valves.

Dysarthria - A speech disorder resulting from muscular problems caused by damage to the brain or nervous system.

Dyspnea - Shortness of breath.

Echocardiography - A method of studying the heart's structure and function by analyzing sound waves bounced off the heart and recorded by an electronic sensor placed on the chest. A computer processes the information to produce a one-, two- or three-dimensional moving picture that shows how the heart and heart valves are functioning.

Edema - Swelling caused by fluid accumulation in body tissues.

Ejection fraction - A measurement of blood that is pumped out of a filled ventricle. The normal rate is 50 percent or more.

Electrocardiogram (ECG or EKG) - A test in which several electronic sensors are placed on the body to monitor electrical activity associated with the heartbeat.

Electroencephalogram (EEG) - A test that can detect and record the brain's electrical activity. The test is done by pasting metal disks, called electrodes, to the scalp.

Electrophysiological study (EPS) - A test that uses cardiac catheterization to study patients who have arrhythmias (abnormal heartbeats). An electrical current stimulates the heart in an effort to provoke an arrhythmia, which is immediately treated with medicine. EPS is used primarily to identify the origin of arrhythmias and to test the effectiveness of medicines used to treat abnormal heart rhythms.

Embolus - Also called embolism; a blood clot that forms in a blood vessel in one part of the body and travels to another part.

Endarterectomy - Surgical removal of plaque deposits or blood clots in an artery.

Endocardium - The smooth membrane covering the inside of the heart. The innermost lining of the heart.

Endothelium - The smooth inner lining of many body structures, including the heart (endocardium) and blood vessels.

Endocarditis - A bacterial infection of the heart's inner lining (endothelium).

Enlarged heart - A state in which the heart is larger than normal due to heredity, long-term heavy exercise, or diseases and disorders such as obesity, high blood pressure, and coronary artery disease.

Enzyme - A complex chemical capable of speeding up specific biochemical processes in the body.

Epicardium - The thin membrane covering the outside surface of the heart muscle.

Estrogen - A female hormone produced by the ovaries that may protect premenopausal women against heart disease. Estrogen production stops after menopause.

Estrogen (or hormone) replacement therapy (ERT or HRT) - Hormones that some women may take to offset the effects of menopause.

Exercise stress test - A common test for diagnosing coronary artery disease, especially in patients who have symptoms of heart disease. The test helps doctors assess blood flow through coronary arteries in response to exercise, usually walking, at varied speeds and for various lengths of time on a treadmill. A stress test may include use of electrocardiography, echocardiography, and injected radioactive substances. Also called exercise test, stress test, or treadmill test.

Familial hypercholesterolemia - A genetic predisposition to dangerously high cholesterol levels.

Fatty acids (fats) - Substances that occur in several forms in foods; different fatty acids have different effects on lipid profiles.

Fibrillation - Rapid, uncoordinated contractions of individual heart muscle fibers. The heart chamber involved can't contract all at once and pumps blood ineffectively, if at all.

First-degree heart block - When an electrical impulse from the heart's upper chambers (the atria) is slowed as it moves through the atria and atrioventricular (AV) node.

Flutter - The rapid, ineffective contractions of any heart chamber. A flutter is considered to be more coordinated than fibrillation.

Fusiform aneurysm - A tube-shaped aneurysm that causes the artery to bulge outward. Involves the entire circumference (outside wall) of the artery.

Gated blood pool scan - An x-ray analysis of how blood pools in the heart during rest and exercise. The test makes use of a radioactive substance injected into the blood to tag or label red cells. The test provides an estimate of the heart's overall ability to pump and its ability to compensate for one or more blocked arteries. Also called MUGA, for multi-unit gated analysis.

Genetic testing - Blood tests that study a person's genes to find out if he or she is at risk for certain diseases that are passed down through family members.

Guidewire - A small, bendable wire that is threaded through an artery; it helps doctors position a catheter so they can perform angioplasty or stent procedures. The guidewire is small enough that it can be inserted into the vessel through a needle, but it is also stiff enough to be threaded "up" the artery.

Heart assist device - A mechanical device that is surgically implanted to ease the workload of the heart.

Heart attack - Death of, or damage to, part of the heart muscle caused by a lack of oxygen-rich blood to the heart.

Heart block - General term for conditions in which the electrical impulse that activates the heart muscle cells is delayed or interrupted somewhere along its path.

Heart failure - See congestive heart failure.

Heart-lung machine - An apparatus that oxygenates and pumps blood to the body during open heart surgery.

Heart murmur -An abnormal heart sound caused by turbulent blood flow. The sound may indicate that blood is flowing through a damaged or overworked heart valve, that there may be a hole in one of the heart's walls, or that there is a narrowing in one of the heart's vessels. Some heart murmurs are a harmless type called innocent heart murmurs, which are common in children and usually do not require treatment.

Heredity - The genetic transmission of a particular quality or trait from parent to child.

High blood pressure - A chronic increase in blood pressure above its normal range.

High density lipoprotein (HDL) - A component of cholesterol, HDL helps protect against heart disease by promoting cholesterol breakdown and removal from the blood; hence, its nickname "good cholesterol."

Holter monitor - A portable device for recording heartbeats over a period of 24 hours or more.

Homocysteine – An amino acid (one of the building blocks that makes up a protein) normally found in small amounts in the blood. Too much homocysteine in the blood may promote the buildup of fatty plaque in the arteries. For some people, high homocysteine levels are genetic. For others, it is because they do not get enough of certain B vitamins in their diet (B-12, B-6, and folic acid). Most people can keep their homocysteine levels in check by eating foods rich in B vitamins. Your doctor may also recommend a vitamin supplement. (Common misspelling: homocystine)

Hormones - Chemicals released into the bloodstream that control different functions in the body, including metabolism, growth, sexual development, and responses to stress or illness.

Hypertension - High blood pressure.

Hypertrophic obstructive cardiomyopathy (HOCM) - An overgrown heart muscle that creates a bulge into the ventricle and impedes blood flow.

Hypertrophy - Enlargement of tissues or organs because of increased workload.

Hyperventilation - Rapid breathing usually caused by anxiety. People feel like they can't get enough air, so they breathe heavily and rapidly, which can lead to numb or tingly arms and legs, or fainting.

Hypoglycemia - Low levels of glucose (sugar) in the blood.

Hypotension - Abnormally low blood pressure.

Hypoxia - Less than normal content of oxygen in the organs and tissues of the body.

Idiopathic - No known cause.

Immunosuppressants - Any medicine that suppresses the body's immune system. These medicines are used to minimize the chances that the body will reject a newly transplanted organ, such as a heart.

Impedance plethysmography - A noninvasive diagnostic test used to evaluate blood flow through the leg.

Incompetent valve - Also called insufficiency; a valve that is not working properly, causing it to leak blood back in the wrong direction.

Infarct - The area of heart tissue permanently damaged by an inadequate supply of oxygen.

Infective endocarditis - An infection of the heart valves and the innermost lining of the heart (the endocardium), caused by bacteria in the bloodstream.

Inferior vena cava - The large vein returning blood from the legs and abdomen to the heart.

Inotropes - Any medicine that increases the strength of the heart's contraction.

Intravascular echocardiography - A combination of echocardiography and cardiac catheterization. A miniature echo device on the tip of a catheter is used to generate images inside the heart and blood vessels.

Introducer sheath - A catheter-like tube that is placed inside a patient's vessel during an interventional procedure to help the doctor with insertion and proper placement of the actual catheter. Also called a sheath.

Ischemia - Decreased blood flow to an organ, usually due to constriction or obstruction of an artery.

Ischemic heart disease - Also called coronary artery disease and coronary heart disease, this term is applied to heart problems caused by narrowing of the coronary arteries, thereby causing a decreased blood supply to the heart.

Ischemic stroke - A type of stroke that is caused by blockage in a blood vessel.

Jugular veins - The veins that carry blood back from the head to the heart.

Left ventricular assist device (LVAD)- A mechanical device that can be placed outside the body or implanted inside the body. An LVAD does not replace the heart—it "assists" or "helps" it pump oxygen-rich blood from the left ventricle to the rest of the body.

Lesion - An injury or wound. An atherosclerotic lesion is an injury to an artery due to hardening of the arteries.

Lipid - A fatty substance that is insoluble (cannot be dissolved) in the blood.

Lipoprotein - A lipid surrounded by a protein; the protein makes it so the lipid is soluble (can be dissolved) in the blood.

Low density lipoprotein (LDL) - The body's primary cholesterol-carrying molecule. High blood levels of LDL increase a person's risk of heart disease by promoting cholesterol attachment and accumulation in blood vessels; hence, the popular nickname "bad cholesterol."

Lumen - The hollow area within a tube, such as a blood vessel.

Magnetic resonance imaging (MRI) - A technique that produces images of the heart and other body structures by measuring the response of certain elements (such as hydrogen) in the body to a magnetic field. When stimulated by radio waves, the elements emit distinctive signals in a magnetic field. MRI can produce detailed pictures of the heart and its various structures without the need to inject a dye.

Maze surgery - A type of heart surgery that is used to treat chronic atrial fibrillation by creating a surgical "maze" of new electrical pathways to let electrical impulses travel easily through the heart. Also called the Maze procedure.

Mitral stenosis - A narrowing of the mitral valve, which controls blood flow from the heart's upper left chamber (the left atrium) to its lower left chamber (the left ventricle). May result from an inherited (congenital) problem or from rheumatic fever.

Mitral valve - The structure that controls blood flow between the heart's left atrium (upper chamber) and left ventricle (lower chamber).

Mitral valve prolapse - A condition that occurs when the leaflets of the mitral valve between the left atrium (upper chamber) and left ventricle (lower chamber) bulge into the atrium and permit backflow of blood into the atrium. The condition is often associated with progressive mitral regurgitation.

Mitral valve regurgitation - Failure of the mitral valve to close properly, causing blood to flow back into the heart's upper left chamber (the left atrium) instead of moving forward into the lower left chamber (the left ventricle).

mm Hg- An abbreviation for millimeters of mercury. Blood pressure is measured in units of mm Hg—how high the pressure inside the arteries would be able to raise a column of mercury.

Monounsaturated fats - A type of fat found in many foods but mainly in avocados and in canola, olive, and peanut oils. Monounsaturated fat tends to lower LDL cholesterol levels, and some studies suggest that it may do so without also lowering HDL cholesterol levels.

Mortality - The total number of deaths from a given disease in a population during an interval of time, usually a year.

Murmur - Noises superimposed on normal heart sounds. They are caused by congenital defects or damaged heart valves that do not close properly and allow blood to leak back into the chamber from which it has come.

Myocardial infarction - A heart attack. The damage or death of an area of the heart muscle (myocardium) resulting from a blocked blood supply to the area. The affected tissue dies, injuring the heart. Symptoms include prolonged, intensive chest pain and a decrease in blood pressure that often causes shock.

Myocardial ischemia - A part of the heart muscle does not receive enough oxygen.

Myocarditis – A rare condition where the heart muscle becomes inflamed as a result of infection, toxic drug poisoning, or diseases like rheumatic fever, diphtheria, or tuberculosis.

Myocardium - The muscular wall of the heart. It contracts to pump blood out of the heart and then relaxes as the heart refills with returning blood.

Myxomatous degeneration - A connective tissue disorder that causes the heart valve tissue to weaken and lose elasticity.

Nitroglycerin - A medicine that helps relax and dilate arteries; often used to treat cardiac chest pain (angina).

Necrosis - Referring to the death of tissue within a certain area.

Noninvasive procedures - Any diagnostic or treatment procedure in which no instrument enters the body.

Obesity - The condition of being significantly overweight. It is usually applied to a condition of 30 percent or more over ideal body weight. Obesity puts a strain on the heart and can increase the chance of developing high blood pressure and diabetes.

Occluded artery - An artery in which the blood flow has been impaired by a blockage.

Open heart surgery - An operation in which the chest and heart are opened surgically while the bloodstream is diverted through a heart-lung (cardiopulmonary bypass) machine.

Pacemaker - A surgically implanted electronic device that helps regulate the heartbeat.

Palpitation - An uncomfortable feeling within the chest caused by an irregular heartbeat.

Pancreas - The organ behind the stomach that helps control blood sugar levels.

Pancreatitis - Swelling (inflammation) of the pancreas.

Paralysis -Loss of the ability to move muscles and feel in part of the body or the whole body. Paralysis may be temporary or permanent.

Patent ductus arteriosus - A congenital defect in which the opening between the aorta and the pulmonary artery does not close after birth.

Percutaneous coronary intervention (PCI)- Any of the noninvasive procedures usually performed in the cardiac catheterization laboratory. Angioplasty is an example of a percutaneous coronary intervention. Also called a transcatheter intervention.

Percutaneous transluminal coronary angioplasty (PTCA) - See angioplasty.

Pericarditis - Inflammation of the outer membrane surrounding the heart. When pericarditis occurs, the amount of fluid between the two layers of the pericardium increases. This increased fluid presses on the heart and restricts its pumping action.

Pericardiocentesis - A diagnostic procedure that uses a needle to withdraw fluid from the sac or membrane surrounding the heart (pericardium).

Pericardium - The outer fibrous sac that surrounds the heart.

Plaque - A deposit of fatty (and other) substances in the inner lining of the artery wall; it is characteristic of atherosclerosis.

Platelets - One of the three types of cells found in blood; they aid in the clotting of the blood.

Polyunsaturated fat - The major fat in most vegetable oils, including corn, safflower, sunflower, and soybean oils. These oils are liquid at room temperature. Polyunsaturated fat actually tends to lower LDL cholesterol levels but may reduce HDL cholesterol levels as well.

Positron emission tomography (PET) - A test that uses information about the energy of certain elements in your body to show whether parts of the heart muscle are alive and working. A PET scan can also show if your heart is getting enough blood to keep the muscle healthy.

Premature ventricular contraction (PVC) - An early or extra heartbeat that happens when the heart's lower chambers (the ventricles) contract too soon, out of sequence with the normal heartbeat.

Prevalence - The total number of cases of a given disease that exist in a population at a specific time.

Pulmonary - Referring to the lungs and respiratory system.

Pulmonary embolism - A condition in which a blood clot that has formed elsewhere in the body travels to the lungs.

Pulmonary valve - The heart valve between the right ventricle and the pulmonary artery that controls blood flow from the heart into the lungs.

Pulmonary vein - The blood vessel that carries newly oxygenated blood from the lungs back to the left atrium of the heart.

Radionuclide imaging - A test in which a harmless radioactive substance is injected into the bloodstream to show information about blood flow through the arteries. Damaged or dead heart muscle can often be identified, as can serious narrowing in an artery.

Radionuclide studies - Any of the diagnostic tests in which a small amount of radioactive material is injected into the bloodstream. The material makes it possible for a special camera to take pictures of the heart.

Radionuclide ventriculography - A diagnostic test used to determine the size and shape of the heart's pumping chambers (the ventricles).

Regurgitation - Backward flow of blood through a defective heart valve.

Renal - Pertaining to the kidneys.

Restenosis- The re-closing or re-narrowing of an artery after an interventional procedure such as angioplasty or stent placement.

Revascularization - A procedure to restore blood flow to the tissues. Coronary artery bypass surgery is an example of a revascularization procedure.

Rheumatic fever - A disease, usually occurring in childhood, that may follow a streptococcal infection. Symptoms may include fever, sore or swollen joints, skin rash, involuntary muscle twitching, and development of nodules under the skin. If the infection involves the heart, scars may form on heart valves, and the heart's outer lining may be damaged.

Rheumatic heart disease - A disease of the heart (mainly affecting the heart's valves) caused by rheumatic fever.

Right ventricular assist device (RVAD) - A mechanical device that can be placed outside the body or implanted inside the body. An RVAD does not replace the heart—it "assists" or "helps" it pump oxygen-poor blood from the right ventricle to the lungs.

Risk factor - An element or condition involving a certain hazard or danger. When referring to heart and blood vessels, a risk factor is associated with an increased chance of developing cardiovascular disease, including stroke.

Rubella - Commonly known as German measles.

Saccular aneurysm - A round aneurysm that bulges out from an artery. Involves only part of the circumference (outside wall) of the artery.

Saturated fat - Type of fat found in foods of animal origin and a few of vegetable origin; they are usually solid at room temperature. Abundant in meat and dairy products, saturated fat tends to increase LDL cholesterol levels, and it may raise the risk of certain types of cancer.

Second-degree heart block - Impulses traveling through the heart's upper chambers (the atria) are delayed in the area between the upper and lower chambers (the AV node) and fail to make the ventricles beat at the right moment.

Septal defect - A hole in the wall of the heart separating the atria or in the wall of the heart separating the ventricles.

Septum - The muscular wall dividing a chamber on the left side of the heart from the chamber on the right.

Sheath - A catheter-like tube that is placed inside a patient's vessel during an interventional procedure to help the doctor with insertion and proper placement of the actual catheter. Also called an introducer sheath.

Shock - A condition in which body function is impaired because the volume of fluid circulating through the body is insufficient to maintain normal metabolism. This may be caused by blood loss or by a disturbance in the function of the circulatory system.

Shunt - A connector that allows blood to flow between two locations.

Sick sinus syndrome - The failure of the sinus node to regulate the heart's rhythm.

Silent ischemia - Episodes of cardiac ischemia that are not accompanied by chest pain.

Sinus (SA) node - The "natural" pacemaker of the heart. The node is a group of specialized cells in the top of the right atrium which produces the electrical impulses that travel down to eventually reach the ventricular muscle, causing the heart to contract.

Sodium - A mineral essential to life found in nearly all plant and animal tissue. Table salt (sodium chloride) is nearly half sodium.

Sphygmomanometer - An instrument used to measure blood pressure.

Stem cells - Special cells in the body that are able to transform into other cells. It is possible for stem cells to transform into heart cells, nerve cells, or other cells of the body, possibly helping to improve the function of failing organs, including the heart.

Stent - A device made of expandable, metal mesh that is placed (by using a balloon catheter) at the site of a narrowing artery. The stent is then expanded and left in place to keep the artery open.

Stenosis - The narrowing or constriction of an opening, such as a blood vessel or heart valve.

Stethoscope - An instrument for listening to sounds within the body.

Stokes-Adams disease - Also called third-degree heart block; a condition that happens when the impulses that pace your heartbeat do not reach the lower chambers of your heart (the ventricles). To make up for this, the ventricles use their own "backup" pacemaker with its slower rate. This rhythm can cause severe dizziness or fainting. Stokes-Adams disease is very serious and can lead to heart failure or death.

Streptococcal infection ("strep" infection) - An infection, usually in the throat, resulting from the presence of streptococcus bacteria.

Streptokinase - A clot-dissolving medicine used to treat heart attack patients.

Sternum - The breastbone.

Stress - Bodily or mental tension resulting from physical, chemical, or emotional factors. Stress can refer to physical exertion as well as mental anxiety.

Stroke - A sudden disruption of blood flow to the brain, either by a clot or a leak in a blood vessel.

Subarachnoid hemorrhage - Bleeding from a blood vessel on the surface of the brain into the space between the brain and the skull.

Sudden death - Death that occurs unexpectedly and instantaneously or shortly after the onset of symptoms. The most common underlying reason for patients dying suddenly is cardiovascular disease, in particular coronary heart disease.

Superior vena cava - The large vein that returns blood from the head and arms to the heart.

Syncope - A temporary, insufficient blood supply to the brain which causes a loss of consciousness. Usually caused by a serious arrhythmia.

Systolic blood pressure - The highest blood pressure measured in the arteries. It occurs when the heart contracts with each heartbeat.

Tachycardia - Accelerated beating of the heart. Paroxysmal tachycardia is a particular form of rapid heart action, occurring in seizures that may last from a few seconds to several days.

Tachypnea - Rapid breathing.

Thallium-201 stress test - An x-ray study that follows the path of radioactive potassium carried by the blood into heart muscle. Damaged or dead muscle can be defined, as can the extent of narrowing in an artery.

Third-degree heart block - Also called Stokes-Adams disease; impulses from the heart's upper chambers (the atria) are completely blocked from reaching the heart's lower chambers (the ventricles). To make up for this, the ventricles use their own "backup" pacemaker with its slower rate.

Thrombolysis - The breaking up of a blood clot.

Thrombosis - A blood clot that forms inside the blood vessel or cavity of the heart.

Thrombolytic therapy - Intravenous or intra-arterial medicines that are used to dissolve blood clots in an artery.

Thrombus - A blood clot.

Thyroid - A gland located in the front of the neck, just below the voice box.

Tissue plasminogen activator (tPA) - A clot-dissolving medicine that is used to treat heart attack and stroke patients.

Trans fat - Created when hydrogen is forced through an ordinary vegetable oil (hydrogenation), converting some polyunsaturates to monounsaturates, and some monounsaturates to saturates. Trans fat, like saturated fat, tends to raise LDL cholesterol levels, and, unlike saturated fat, trans fat also lowers HDL cholesterol levels at the same time.

Transcatheter intervention - Any of the noninvasive procedures usually performed in the cardiac catheterization laboratory. Angioplasty is an example of a transcatheter intervention. Also called a percutaneous coronary intervention (PCI).

Transesophageal echocardiography - A diagnostic test that analyzes sound waves bounced off the heart. The sound waves are sent through a tube-like device inserted in the mouth and passed down the esophagus (food pipe), which ends near the heart. This technique is useful in studying patients whose heart and vessels, for various reasons, are difficult to assess with standard echocardiography.

Transient ischemic attack (TIA) - A stroke-like event that lasts only for a short time and is caused by a temporarily blocked blood vessel.

Transplantation - Replacing a failing organ with a healthy one from a donor.

Tricuspid valve - The structure that controls blood flow from the heart's upper right chamber (the right atrium) into the lower right chamber (the right ventricle).

Triglyceride - The most common fatty substance found in the blood; normally stored as an energy source in fat tissue. High triglyceride levels may thicken the blood and make a person more susceptible to clot formation. High triglyceride levels tend to accompany high cholesterol levels and other risk factors for heart disease, such as obesity.

Ultrasound - High-frequency sound vibrations, which cannot be heard by the human ear, used in medical diagnosis.

Valve replacement - An operation to replace a heart valve that is either blocking normal blood flow or causing blood to leak backward into the heart (regurgitation).

Valvuloplasty - Reshaping of a heart valve with surgical or catheter techniques.

Varicose vein - Any vein that is abnormally dilated (widened).

Vascular - Pertaining to the blood vessels.

Vasodilators - Any medicine that dilates (widens) the arteries.

Vasopressors - Any medicine that elevates blood pressure.

Vein - Any one of a series of blood vessels of the vascular system that carries blood from various parts of the body back to the heart, returning oxygen-poor blood to the heart.

Ventricle (right and left) - One of the two lower chambers of the heart.

Ventricular fibrillation - A condition in which the ventricles contract in a rapid, unsynchronized fashion. When fibrillation occurs, the ventricles cannot pump blood throughout the body.

Ventricular tachycardia - An arrhythmia (abnormal heartbeat) in the ventricle characterized by a very fast heartbeat.

Vertigo - A feeling of dizziness or spinning.

Wolff-Parkinson-White syndrome - A condition in which an extra electrical pathway connects the atria (two upper chambers) and the ventricles (two lower chambers). It may cause a rapid heartbeat.

X-ray - Form of radiation used to create a picture of internal body structures on film.

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