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Heart-Assist Devices: Small pumps, often implantable, designed for temporarily assisting the heart, usually the LEFT VENTRICLE, to pump blood. They consist of a pumping chamber and a power source, which may be partially or totally external to the body and activated by electromagnetic motors.Heart: The hollow, muscular organ that maintains the circulation of the blood.Heart Failure: A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (VENTRICULAR DYSFUNCTION), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as MYOCARDIAL INFARCTION.Heart Transplantation: The transference of a heart from one human or animal to another.Prosthesis Implantation: Surgical insertion of a prosthesis.Heart Rate: The number of times the HEART VENTRICLES contract per unit of time, usually per minute.Equipment Design: Methods of creating machines and devices.Shock, Cardiogenic: Shock resulting from diminution of cardiac output in heart disease.Device Removal: Removal of an implanted therapeutic or prosthetic device.Assisted Circulation: Pumping that aids the natural activity of the heart. (Dorland, 27th ed)Prosthesis Design: The plan and delineation of prostheses in general or a specific prosthesis.Cardiomyopathy, Dilated: A form of CARDIAC MUSCLE disease that is characterized by ventricular dilation, VENTRICULAR DYSFUNCTION, and HEART FAILURE. Risk factors include SMOKING; ALCOHOL DRINKING; HYPERTENSION; INFECTION; PREGNANCY; and mutations in the LMNA gene encoding LAMIN TYPE A, a NUCLEAR LAMINA protein.Heart Diseases: Pathological conditions involving the HEART including its structural and functional abnormalities.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Ventricular Function, Left: The hemodynamic and electrophysiological action of the left HEART VENTRICLE. Its measurement is an important aspect of the clinical evaluation of patients with heart disease to determine the effects of the disease on cardiac performance.Hemodynamics: The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.Heart, Artificial: A pumping mechanism that duplicates the output, rate, and blood pressure of the natural heart. It may replace the function of the entire heart or a portion of it, and may be an intracorporeal, extracorporeal, or paracorporeal heart. (Dorland, 28th ed)Extracorporeal Membrane Oxygenation: Application of a life support system that circulates the blood through an oxygenating system, which may consist of a pump, a membrane oxygenator, and a heat exchanger. Examples of its use are to assist victims of smoke inhalation injury, respiratory failure, and cardiac failure.Equipment Failure: Failure of equipment to perform to standard. The failure may be due to defects or improper use.Equipment Safety: Freedom of equipment from actual or potential hazards.Device Approval: Process that is gone through in order for a device to receive approval by a government regulatory agency. This includes any required preclinical or clinical testing, review, submission, and evaluation of the applications and test results, and post-marketing surveillance. It is not restricted to FDA.Cardiomyopathies: A group of diseases in which the dominant feature is the involvement of the CARDIAC MUSCLE itself. Cardiomyopathies are classified according to their predominant pathophysiological features (DILATED CARDIOMYOPATHY; HYPERTROPHIC CARDIOMYOPATHY; RESTRICTIVE CARDIOMYOPATHY) or their etiological/pathological factors (CARDIOMYOPATHY, ALCOHOLIC; ENDOCARDIAL FIBROELASTOSIS).Ventricular Dysfunction, Right: A condition in which the RIGHT VENTRICLE of the heart was functionally impaired. This condition usually leads to HEART FAILURE or MYOCARDIAL INFARCTION, and other cardiovascular complications. Diagnosis is made by measuring the diminished ejection fraction and a depressed level of motility of the right ventricular wall.Heart Defects, Congenital: Developmental abnormalities involving structures of the heart. These defects are present at birth but may be discovered later in life.Intra-Aortic Balloon Pumping: Counterpulsation in which a pumping unit synchronized with the patient's electrocardiogram rapidly fills a balloon in the aorta with helium or carbon dioxide in early diastole and evacuates the balloon at the onset of systole. As the balloon inflates, it raises aortic diastolic pressure, and as it deflates, it lowers aortic systolic pressure. The result is a decrease in left ventricular work and increased myocardial and peripheral perfusion.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Miniaturization: The design or construction of objects greatly reduced in scale.Ventricular Dysfunction, Left: A condition in which the LEFT VENTRICLE of the heart was functionally impaired. This condition usually leads to HEART FAILURE; MYOCARDIAL INFARCTION; and other cardiovascular complications. Diagnosis is made by measuring the diminished ejection fraction and a depressed level of motility of the left ventricular wall.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Heart Ventricles: The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.Hydrodynamics: The motion of fluids, especially noncompressible liquids, under the influence of internal and external forces.Biomedical Engineering: Application of principles and practices of engineering science to biomedical research and health care.Compassionate Use Trials: Providing an investigational therapy to a patient who is not eligible to receive that therapy in a clinical trial, but who has a serious or life-threatening illness for which other treatments are not available. Compassionate use trials allow patients to receive promising but not yet fully studied or approved therapies when no other treatment option exists. Also called expanded access trial.Waiting Lists: Prospective patient listings for appointments or treatments.Self-Help Devices: Devices, not affixed to the body, designed to help persons having musculoskeletal or neuromuscular disabilities to perform activities involving movement.Myocardium: The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.Pulsatile Flow: Rhythmic, intermittent propagation of a fluid through a BLOOD VESSEL or piping system, in contrast to constant, smooth propagation, which produces laminar flow.Cardiac Surgical Procedures: Surgery performed on the heart.Oxygenators: Devices which mechanically oxygenate venous blood extracorporeally. They are used in combination with one or more pumps for maintaining circulation during open heart surgery and for assisting the circulation in patients seriously ill with some cardiac and pulmonary disorders. (UMDNS, 1999)Heart Atria: The chambers of the heart, to which the BLOOD returns from the circulation.Stroke Volume: The amount of BLOOD pumped out of the HEART per beat, not to be confused with cardiac output (volume/time). It is calculated as the difference between the end-diastolic volume and the end-systolic volume.Fetal Heart: The heart of the fetus of any viviparous animal. It refers to the heart in the postembryonic period and is differentiated from the embryonic heart (HEART/embryology) only on the basis of time.Oxygenators, Membrane: Devices in which blood and oxygen are separated by a semipermeable membrane, generally of Teflon or polypropylene, across which gas exchange occurs. The membrane may be arranged as a series of parallel plates or as a number of hollow fibers; in the latter arrangement, the blood may flow inside the fibers, which are surrounded by gas, or the blood may flow outside the fibers and the gas inside the fibers. (Dorland, 28th ed)Cardiac Output, Low: A state of subnormal or depressed cardiac output at rest or during stress. It is a characteristic of CARDIOVASCULAR DISEASES, including congenital, valvular, rheumatic, hypertensive, coronary, and cardiomyopathic. The serious form of low cardiac output is characterized by marked reduction in STROKE VOLUME, and systemic vasoconstriction resulting in cold, pale, and sometimes cyanotic extremities.Artificial Organs: Devices intended to replace non-functioning organs. They may be temporary or permanent. Since they are intended always to function as the natural organs they are replacing, they should be differentiated from PROSTHESES AND IMPLANTS and specific types of prostheses which, though also replacements for body parts, are frequently cosmetic (EYE, ARTIFICIAL) as well as functional (ARTIFICIAL LIMBS).Sternotomy: Making an incision in the STERNUM.Intrauterine Devices: Contraceptive devices placed high in the uterine fundus.Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Myocytes, Cardiac: Striated muscle cells found in the heart. They are derived from cardiac myoblasts (MYOBLASTS, CARDIAC).Heart Valves: Flaps of tissue that prevent regurgitation of BLOOD from the HEART VENTRICLES to the HEART ATRIA or from the PULMONARY ARTERIES or AORTA to the ventricles.Echocardiography, Transesophageal: Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues using a transducer placed in the esophagus.Myocardial Contraction: Contractile activity of the MYOCARDIUM.Ventricular Function, Right: The hemodynamic and electrophysiological action of the right HEART VENTRICLE.Clenbuterol: A substituted phenylaminoethanol that has beta-2 adrenomimetic properties at very low doses. It is used as a bronchodilator in asthma.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Prosthesis-Related Infections: Infections resulting from the implantation of prosthetic devices. The infections may be acquired from intraoperative contamination (early) or hematogenously acquired from other sites (late).Kidneys, Artificial: Devices which can substitute for normally functioning KIDNEYS in removing components from the blood by DIALYSIS that are normally eliminated in the URINE.Myocardial Ischemia: A disorder of cardiac function caused by insufficient blood flow to the muscle tissue of the heart. The decreased blood flow may be due to narrowing of the coronary arteries (CORONARY ARTERY DISEASE), to obstruction by a thrombus (CORONARY THROMBOSIS), or less commonly, to diffuse narrowing of arterioles and other small vessels within the heart. Severe interruption of the blood supply to the myocardial tissue may result in necrosis of cardiac muscle (MYOCARDIAL INFARCTION).Risk Assessment: The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)Prostheses and Implants: Artificial substitutes for body parts, and materials inserted into tissue for functional, cosmetic, or therapeutic purposes. Prostheses can be functional, as in the case of artificial arms and legs, or cosmetic, as in the case of an artificial eye. Implants, all surgically inserted or grafted into the body, tend to be used therapeutically. IMPLANTS, EXPERIMENTAL is available for those used experimentally.Ventricular Remodeling: The geometric and structural changes that the HEART VENTRICLES undergo, usually following MYOCARDIAL INFARCTION. It comprises expansion of the infarct and dilatation of the healthy ventricle segments. While most prevalent in the left ventricle, it can also occur in the right ventricle.Maintenance: The upkeep of property or equipment.Equipment and Supplies: Expendable and nonexpendable equipment, supplies, apparatus, and instruments that are used in diagnostic, surgical, therapeutic, scientific, and experimental procedures.Recovery of Function: A partial or complete return to the normal or proper physiologic activity of an organ or part following disease or trauma.Counterpulsation: A technique for assisting the circulation by decreasing the afterload of the left ventricle and augmenting the diastolic pressure. It may be achieved by intra-aortic balloon, or by implanting a special pumping device in the chest, or externally by applying a negative pressure to the lower extremities during cardiac systole.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Severity of Illness Index: Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.Bioartificial Organs: Artificial organs that are composites of biomaterials and cells. The biomaterial can act as a membrane (container) as in BIOARTIFICIAL LIVER or a scaffold as in bioartificial skin.Cholecystolithiasis: Presence or formation of GALLSTONES in the GALLBLADDER.Product Surveillance, Postmarketing: Surveillance of drugs, devices, appliances, etc., for efficacy or adverse effects, after they have been released for general sale.Cardiac Resynchronization Therapy Devices: Types of artificial pacemakers with implantable leads to be placed at multiple intracardial sites. They are used to treat various cardiac conduction disturbances which interfere with the timing of contraction of the ventricles. They may or may not include defibrillating electrodes (IMPLANTABLE DEFIBRILLATORS) as well.Echocardiography: Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic.Models, Cardiovascular: Theoretical representations that simulate the behavior or activity of the cardiovascular system, processes, or phenomena; includes the use of mathematical equations, computers and other electronic equipment.Fatal Outcome: Death resulting from the presence of a disease in an individual, as shown by a single case report or a limited number of patients. This should be differentiated from DEATH, the physiological cessation of life and from MORTALITY, an epidemiological or statistical concept.Postoperative Care: The period of care beginning when the patient is removed from surgery and aimed at meeting the patient's psychological and physical needs directly after surgery. (From Dictionary of Health Services Management, 2d ed)Survival Analysis: A class of statistical procedures for estimating the survival function (function of time, starting with a population 100% well at a given time and providing the percentage of the population still well at later times). The survival analysis is then used for making inferences about the effects of treatments, prognostic factors, exposures, and other covariates on the function.Durable Medical Equipment: Devices which are very resistant to wear and may be used over a long period of time. They include items such as wheelchairs, hospital beds, artificial limbs, etc.Heart Block: Impaired conduction of cardiac impulse that can occur anywhere along the conduction pathway, such as between the SINOATRIAL NODE and the right atrium (SA block) or between atria and ventricles (AV block). Heart blocks can be classified by the duration, frequency, or completeness of conduction block. Reversibility depends on the degree of structural or functional defects.Catheters: A flexible, tubular device that is used to carry fluids into or from a blood vessel, hollow organ, or body cavity.Myocarditis: Inflammatory processes of the muscular walls of the heart (MYOCARDIUM) which result in injury to the cardiac muscle cells (MYOCYTES, CARDIAC). Manifestations range from subclinical to sudden death (DEATH, SUDDEN). Myocarditis in association with cardiac dysfunction is classified as inflammatory CARDIOMYOPATHY usually caused by INFECTION, autoimmune diseases, or responses to toxic substances. Myocarditis is also a common cause of DILATED CARDIOMYOPATHY and other cardiomyopathies.Cardiopulmonary Bypass: Diversion of the flow of blood from the entrance of the right atrium directly to the aorta (or femoral artery) via an oxygenator thus bypassing both the heart and lungs.Thrombosis: Formation and development of a thrombus or blood clot in the blood vessel.Computer-Aided Design: The use of computers for designing and/or manufacturing of anything, including drugs, surgical procedures, orthotics, and prosthetics.Cardiotonic Agents: Agents that have a strengthening effect on the heart or that can increase cardiac output. They may be CARDIAC GLYCOSIDES; SYMPATHOMIMETICS; or other drugs. They are used after MYOCARDIAL INFARCT; CARDIAC SURGICAL PROCEDURES; in SHOCK; or in congestive heart failure (HEART FAILURE).Ventricular Pressure: The pressure within a CARDIAC VENTRICLE. Ventricular pressure waveforms can be measured in the beating heart by catheterization or estimated using imaging techniques (e.g., DOPPLER ECHOCARDIOGRAPHY). The information is useful in evaluating the function of the MYOCARDIUM; CARDIAC VALVES; and PERICARDIUM, particularly with simultaneous measurement of other (e.g., aortic or atrial) pressures.Feasibility Studies: Studies to determine the advantages or disadvantages, practicability, or capability of accomplishing a projected plan, study, or project.Postoperative Complications: Pathologic processes that affect patients after a surgical procedure. They may or may not be related to the disease for which the surgery was done, and they may or may not be direct results of the surgery.Survival Rate: The proportion of survivors in a group, e.g., of patients, studied and followed over a period, or the proportion of persons in a specified group alive at the beginning of a time interval who survive to the end of the interval. It is often studied using life table methods.United StatesSeptal Occluder Device: A CATHETER-delivered implant used for closing abnormal holes in the cardiovascular system, especially HEART SEPTAL DEFECTS; or passageways intentionally made during cardiovascular surgical procedures.Preoperative Period: The period before a surgical operation.Myocardial Infarction: NECROSIS of the MYOCARDIUM caused by an obstruction of the blood supply to the heart (CORONARY CIRCULATION).Foramen Ovale, Patent: A condition in which the FORAMEN OVALE in the ATRIAL SEPTUM fails to close shortly after birth. This results in abnormal communications between the two upper chambers of the heart. An isolated patent ovale foramen without other structural heart defects is usually of no hemodynamic significance.Hemorrhage: Bleeding or escape of blood from a vessel.Kaplan-Meier Estimate: A nonparametric method of compiling LIFE TABLES or survival tables. It combines calculated probabilities of survival and estimates to allow for observations occurring beyond a measurement threshold, which are assumed to occur randomly. Time intervals are defined as ending each time an event occurs and are therefore unequal. (From Last, A Dictionary of Epidemiology, 1995)Heart Valve Prosthesis Implantation: Surgical insertion of synthetic material to repair injured or diseased heart valves.Heart Function Tests: Examinations used to diagnose and treat heart conditions.Predictive Value of Tests: In screening and diagnostic tests, the probability that a person with a positive test is a true positive (i.e., has the disease), is referred to as the predictive value of a positive test; whereas, the predictive value of a negative test is the probability that the person with a negative test does not have the disease. Predictive value is related to the sensitivity and specificity of the test.Pulmonary Wedge Pressure: The blood pressure as recorded after wedging a CATHETER in a small PULMONARY ARTERY; believed to reflect the PRESSURE in the pulmonary CAPILLARIES.Materials Testing: The testing of materials and devices, especially those used for PROSTHESES AND IMPLANTS; SUTURES; TISSUE ADHESIVES; etc., for hardness, strength, durability, safety, efficacy, and biocompatibility.Anticoagulants: Agents that prevent clotting.Heart Arrest, Induced: A procedure to stop the contraction of MYOCARDIUM during HEART SURGERY. It is usually achieved with the use of chemicals (CARDIOPLEGIC SOLUTIONS) or cold temperature (such as chilled perfusate).Prosthesis Failure: Malfunction of implantation shunts, valves, etc., and prosthesis loosening, migration, and breaking.Blood Circulation: The movement of the BLOOD as it is pumped through the CARDIOVASCULAR SYSTEM.Microfluidic Analytical Techniques: Methods utilizing the principles of MICROFLUIDICS for sample handling, reagent mixing, and separation and detection of specific components in fluids.Phonocardiography: Graphic registration of the heart sounds picked up as vibrations and transformed by a piezoelectric crystal microphone into a varying electrical output according to the stresses imposed by the sound waves. The electrical output is amplified by a stethograph amplifier and recorded by a device incorporated into the electrocardiograph or by a multichannel recording machine.Extracorporeal Circulation: Diversion of blood flow through a circuit located outside the body but continuous with the bodily circulation.Cardiovascular Infections: Pathological conditions of the CARDIOVASCULAR SYSTEM caused by infections.Cardiovascular Agents: Agents that affect the rate or intensity of cardiac contraction, blood vessel diameter, or blood volume.Thromboembolism: Obstruction of a blood vessel (embolism) by a blood clot (THROMBUS) in the blood stream.Multiple Organ Failure: A progressive condition usually characterized by combined failure of several organs such as the lungs, liver, kidney, along with some clotting mechanisms, usually postinjury or postoperative.Cardiac Resynchronization Therapy: The restoration of the sequential order of contraction and relaxation of the HEART ATRIA and HEART VENTRICLES by atrio-biventricular pacing.Thoracotomy: Surgical incision into the chest wall.Cardiac Catheterization: Procedures in which placement of CARDIAC CATHETERS is performed for therapeutic or diagnostic procedures.Endomyocardial Fibrosis: A condition characterized by the thickening of the ventricular ENDOCARDIUM and subendocardium (MYOCARDIUM), seen mostly in children and young adults in the TROPICAL CLIMATE. The fibrous tissue extends from the apex toward and often involves the HEART VALVES causing restrictive blood flow into the respective ventricles (CARDIOMYOPATHY, RESTRICTIVE).Magnetics: The study of MAGNETIC PHENOMENA.Defibrillators, Implantable: Implantable devices which continuously monitor the electrical activity of the heart and automatically detect and terminate ventricular tachycardia (TACHYCARDIA, VENTRICULAR) and VENTRICULAR FIBRILLATION. They consist of an impulse generator, batteries, and electrodes.Anterior Wall Myocardial Infarction: MYOCARDIAL INFARCTION in which the anterior wall of the heart is involved. Anterior wall myocardial infarction is often caused by occlusion of the left anterior descending coronary artery. It can be categorized as anteroseptal or anterolateral wall myocardial infarction.Oxygen Consumption: The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)Quality of Life: A generic concept reflecting concern with the modification and enhancement of life attributes, e.g., physical, political, moral and social environment; the overall condition of a human life.Rheology: The study of the deformation and flow of matter, usually liquids or fluids, and of the plastic flow of solids. The concept covers consistency, dilatancy, liquefaction, resistance to flow, shearing, thixotrophy, and VISCOSITY.Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Catheterization, Swan-Ganz: Placement of a balloon-tipped catheter into the pulmonary artery through the antecubital, subclavian, and sometimes the femoral vein. It is used to measure pulmonary artery pressure and pulmonary artery wedge pressure which reflects left atrial pressure and left ventricular end-diastolic pressure. The catheter is threaded into the right atrium, the balloon is inflated and the catheter follows the blood flow through the tricuspid valve into the right ventricle and out into the pulmonary artery.Cohort Studies: Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.Central Venous Pressure: The blood pressure in the central large VEINS of the body. It is distinguished from peripheral venous pressure which occurs in an extremity.Tachycardia, Ventricular: An abnormally rapid ventricular rhythm usually in excess of 150 beats per minute. It is generated within the ventricle below the BUNDLE OF HIS, either as autonomic impulse formation or reentrant impulse conduction. Depending on the etiology, onset of ventricular tachycardia can be paroxysmal (sudden) or nonparoxysmal, its wide QRS complexes can be uniform or polymorphic, and the ventricular beating may be independent of the atrial beating (AV dissociation).Chronic Disease: Diseases which have one or more of the following characteristics: they are permanent, leave residual disability, are caused by nonreversible pathological alteration, require special training of the patient for rehabilitation, or may be expected to require a long period of supervision, observation, or care. (Dictionary of Health Services Management, 2d ed)Patient Selection: Criteria and standards used for the determination of the appropriateness of the inclusion of patients with specific conditions in proposed treatment plans and the criteria used for the inclusion of subjects in various clinical trials and other research protocols.Arterial Pressure: The blood pressure in the ARTERIES. It is commonly measured with a SPHYGMOMANOMETER on the upper arm which represents the arterial pressure in the BRACHIAL ARTERY.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Echocardiography, Doppler: Measurement of intracardiac blood flow using an M-mode and/or two-dimensional (2-D) echocardiogram while simultaneously recording the spectrum of the audible Doppler signal (e.g., velocity, direction, amplitude, intensity, timing) reflected from the moving column of red blood cells.Cardiac Output: The volume of BLOOD passing through the HEART per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with STROKE VOLUME (volume per beat).Models, Animal: Non-human animals, selected because of specific characteristics, for use in experimental research, teaching, or testing.Catheterization: Use or insertion of a tubular device into a duct, blood vessel, hollow organ, or body cavity for injecting or withdrawing fluids for diagnostic or therapeutic purposes. It differs from INTUBATION in that the tube here is used to restore or maintain patency in obstructions.Prognosis: A prediction of the probable outcome of a disease based on a individual's condition and the usual course of the disease as seen in similar situations.Exercise Test: Controlled physical activity which is performed in order to allow assessment of physiological functions, particularly cardiovascular and pulmonary, but also aerobic capacity. Maximal (most intense) exercise is usually required but submaximal exercise is also used.Coronary Disease: An imbalance between myocardial functional requirements and the capacity of the CORONARY VESSELS to supply sufficient blood flow. It is a form of MYOCARDIAL ISCHEMIA (insufficient blood supply to the heart muscle) caused by a decreased capacity of the coronary vessels.Natriuretic Peptide, Brain: A PEPTIDE that is secreted by the BRAIN and the HEART ATRIA, stored mainly in cardiac ventricular MYOCARDIUM. It can cause NATRIURESIS; DIURESIS; VASODILATION; and inhibits secretion of RENIN and ALDOSTERONE. It improves heart function. It contains 32 AMINO ACIDS.Optical Devices: Products or parts of products used to detect, manipulate, or analyze light, such as LENSES, refractors, mirrors, filters, prisms, and OPTICAL FIBERS.Pulmonary Artery: The short wide vessel arising from the conus arteriosus of the right ventricle and conveying unaerated blood to the lungs.Biological Markers: Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.Intrauterine Devices, Copper: Intrauterine contraceptive devices that depend on the release of metallic copper.Postoperative Period: The period following a surgical operation.Acute Disease: Disease having a short and relatively severe course.Ventricular Fibrillation: A potentially lethal cardiac arrhythmia that is characterized by uncoordinated extremely rapid firing of electrical impulses (400-600/min) in HEART VENTRICLES. Such asynchronous ventricular quivering or fibrillation prevents any effective cardiac output and results in unconsciousness (SYNCOPE). It is one of the major electrocardiographic patterns seen with CARDIAC ARREST.Suture Techniques: Techniques for securing together the edges of a wound, with loops of thread or similar materials (SUTURES).Equipment Failure Analysis: The evaluation of incidents involving the loss of function of a device. These evaluations are used for a variety of purposes such as to determine the failure rates, the causes of failures, costs of failures, and the reliability and maintainability of devices.Hospital Mortality: A vital statistic measuring or recording the rate of death from any cause in hospitalized populations.Respiration, Artificial: Any method of artificial breathing that employs mechanical or non-mechanical means to force the air into and out of the lungs. Artificial respiration or ventilation is used in individuals who have stopped breathing or have RESPIRATORY INSUFFICIENCY to increase their intake of oxygen (O2) and excretion of carbon dioxide (CO2).Preoperative Care: Care given during the period prior to undergoing surgery when psychological and physical preparations are made according to the special needs of the individual patient. This period spans the time between admission to the hospital to the time the surgery begins. (From Dictionary of Health Services Management, 2d ed)Adrenergic beta-Agonists: Drugs that selectively bind to and activate beta-adrenergic receptors.Mitral Valve Insufficiency: Backflow of blood from the LEFT VENTRICLE into the LEFT ATRIUM due to imperfect closure of the MITRAL VALVE. This can lead to mitral valve regurgitation.Infection: Invasion of the host organism by microorganisms that can cause pathological conditions or diseases.Sarcoplasmic Reticulum Calcium-Transporting ATPases: Calcium-transporting ATPases that catalyze the active transport of CALCIUM into the SARCOPLASMIC RETICULUM vesicles from the CYTOPLASM. They are primarily found in MUSCLE CELLS and play a role in the relaxation of MUSCLES.Heart Valve Prosthesis: A device that substitutes for a heart valve. It may be composed of biological material (BIOPROSTHESIS) and/or synthetic material.Heart Arrest: Cessation of heart beat or MYOCARDIAL CONTRACTION. If it is treated within a few minutes, heart arrest can be reversed in most cases to normal cardiac rhythm and effective circulation.Registries: The systems and processes involved in the establishment, support, management, and operation of registers, e.g., disease registers.Postoperative Hemorrhage: Hemorrhage following any surgical procedure. It may be immediate or delayed and is not restricted to the surgical wound.Stress, Mechanical: A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.Respiratory Insufficiency: Failure to adequately provide oxygen to cells of the body and to remove excess carbon dioxide from them. (Stedman, 25th ed)Chi-Square Distribution: A distribution in which a variable is distributed like the sum of the squares of any given independent random variable, each of which has a normal distribution with mean of zero and variance of one. The chi-square test is a statistical test based on comparison of a test statistic to a chi-square distribution. The oldest of these tests are used to detect whether two or more population distributions differ from one another.Cost Savings: Reductions in all or any portion of the costs of providing goods or services. Savings may be incurred by the provider or the consumer.Cause of Death: Factors which produce cessation of all vital bodily functions. They can be analyzed from an epidemiologic viewpoint.Heart Failure, Systolic: Heart failure caused by abnormal myocardial contraction during SYSTOLE leading to defective cardiac emptying.Perfusion: Treatment process involving the injection of fluid into an organ or tissue.Pacemaker, Artificial: A device designed to stimulate, by electric impulses, contraction of the heart muscles. It may be temporary (external) or permanent (internal or internal-external).Heart Injuries: General or unspecified injuries to the heart.Cardiopulmonary Resuscitation: The artificial substitution of heart and lung action as indicated for HEART ARREST resulting from electric shock, DROWNING, respiratory arrest, or other causes. The two major components of cardiopulmonary resuscitation are artificial ventilation (RESPIRATION, ARTIFICIAL) and closed-chest CARDIAC MASSAGE.Blood Flow Velocity: A value equal to the total volume flow divided by the cross-sectional area of the vascular bed.United States Food and Drug Administration: An agency of the PUBLIC HEALTH SERVICE concerned with the overall planning, promoting, and administering of programs pertaining to maintaining standards of quality of foods, drugs, therapeutic devices, etc.Heart Septum: This structure includes the thin muscular atrial septum between the two HEART ATRIA, and the thick muscular ventricular septum between the two HEART VENTRICLES.Cardiomegaly: Enlargement of the HEART, usually indicated by a cardiothoracic ratio above 0.50. Heart enlargement may involve the right, the left, or both HEART VENTRICLES or HEART ATRIA. Cardiomegaly is a nonspecific symptom seen in patients with chronic systolic heart failure (HEART FAILURE) or several forms of CARDIOMYOPATHIES.Age Factors: Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.Heart Septal Defects, Atrial: Developmental abnormalities in any portion of the ATRIAL SEPTUM resulting in abnormal communications between the two upper chambers of the heart. Classification of atrial septal defects is based on location of the communication and types of incomplete fusion of atrial septa with the ENDOCARDIAL CUSHIONS in the fetal heart. They include ostium primum, ostium secundum, sinus venosus, and coronary sinus defects.Reoperation: A repeat operation for the same condition in the same patient due to disease progression or recurrence, or as followup to failed previous surgery.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Proportional Hazards Models: Statistical models used in survival analysis that assert that the effect of the study factors on the hazard rate in the study population is multiplicative and does not change over time.Lab-On-A-Chip Devices: Microdevices that combine microfluidics technology with electrical and/or mechanical functions for analyzing very small fluid volumes. They consist of microchannels etched into substrates made of silicon, glass, or polymer using processes similar to photolithography. The test fluids in the channels can then interact with different elements such as electrodes, photodetectors, chemical sensors, pumps, and valves.Cardiac Pacing, Artificial: Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Rheumatic Heart Disease: Cardiac manifestation of systemic rheumatological conditions, such as RHEUMATIC FEVER. Rheumatic heart disease can involve any part the heart, most often the HEART VALVES and the ENDOCARDIUM.Statistics, Nonparametric: A class of statistical methods applicable to a large set of probability distributions used to test for correlation, location, independence, etc. In most nonparametric statistical tests, the original scores or observations are replaced by another variable containing less information. An important class of nonparametric tests employs the ordinal properties of the data. Another class of tests uses information about whether an observation is above or below some fixed value such as the median, and a third class is based on the frequency of the occurrence of runs in the data. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1284; Corsini, Concise Encyclopedia of Psychology, 1987, p764-5)Heart Rate, Fetal: The heart rate of the FETUS. The normal range at term is between 120 and 160 beats per minute.Incidence: The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from PREVALENCE, which refers to all cases, new or old, in the population at a given time.American Heart Association: A voluntary organization concerned with the prevention and treatment of heart and vascular diseases.Cost-Benefit Analysis: A method of comparing the cost of a program with its expected benefits in dollars (or other currency). The benefit-to-cost ratio is a measure of total return expected per unit of money spent. This analysis generally excludes consideration of factors that are not measured ultimately in economic terms. Cost effectiveness compares alternative ways to achieve a specific set of results.Myocardial Reperfusion Injury: Damage to the MYOCARDIUM resulting from MYOCARDIAL REPERFUSION (restoration of blood flow to ischemic areas of the HEART.) Reperfusion takes place when there is spontaneous thrombolysis, THROMBOLYTIC THERAPY, collateral flow from other coronary vascular beds, or reversal of vasospasm.Aortic Valve: The valve between the left ventricle and the ascending aorta which prevents backflow into the left ventricle.Medical Device Legislation: Laws and regulations pertaining to devices used in medicine, proposed for enactment, or enacted by a legislative body.Case-Control Studies: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.Adrenergic beta-Antagonists: Drugs that bind to but do not activate beta-adrenergic receptors thereby blocking the actions of beta-adrenergic agonists. Adrenergic beta-antagonists are used for treatment of hypertension, cardiac arrhythmias, angina pectoris, glaucoma, migraine headaches, and anxiety.Sheep: Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS.Renal Insufficiency: Conditions in which the KIDNEYS perform below the normal level in the ability to remove wastes, concentrate URINE, and maintain ELECTROLYTE BALANCE; BLOOD PRESSURE; and CALCIUM metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of PROTEINURIA) and reduction in GLOMERULAR FILTRATION RATE.Ventricular Function: The hemodynamic and electrophysiological action of the HEART VENTRICLES.Orthotic Devices: Apparatus used to support, align, prevent, or correct deformities or to improve the function of movable parts of the body.Intrauterine Devices, Medicated: Intrauterine devices that release contraceptive agents.Heart Failure, Diastolic: Heart failure caused by abnormal myocardial relaxation during DIASTOLE leading to defective cardiac filling.Blood Pressure: PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.Combined Modality Therapy: The treatment of a disease or condition by several different means simultaneously or sequentially. Chemoimmunotherapy, RADIOIMMUNOTHERAPY, chemoradiotherapy, cryochemotherapy, and SALVAGE THERAPY are seen most frequently, but their combinations with each other and surgery are also used.Telemetry: Transmission of the readings of instruments to a remote location by means of wires, radio waves, or other means. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Regional Blood Flow: The flow of BLOOD through or around an organ or region of the body.