Cardiography, Impedance
A type of impedance plethysmography in which bioelectrical impedance is measured between electrodes positioned around the neck and around the lower thorax. It is used principally to calculate stroke volume and cardiac volume, but it is also related to myocardial contractility, thoracic fluid content, and circulation to the extremities.
Plethysmography, Impedance
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).
Isosorbide
Heart Sounds
The sounds heard over the cardiac region produced by the functioning of the heart. There are four distinct sounds: the first occurs at the beginning of SYSTOLE and is heard as a "lubb" sound; the second is produced by the closing of the AORTIC VALVE and PULMONARY VALVE and is heard as a "dupp" sound; the third is produced by vibrations of the ventricular walls when suddenly distended by the rush of blood from the HEART ATRIA; and the fourth is produced by atrial contraction and ventricular filling.
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.
Hemodynamics
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.
Dielectric Spectroscopy
A technique of measuring the dielectric properties of materials, which vary over a range of frequencies depending on the physical properties of the material. The technique involves measuring, over a range of frequencies, ELECTRICAL IMPEDANCE and phase shift of an electric field as it passes through the material.
Vascular Resistance
The force that opposes the flow of BLOOD through a vascular bed. It is equal to the difference in BLOOD PRESSURE across the vascular bed divided by the CARDIAC OUTPUT.
Monitoring, Physiologic
The continuous measurement of physiological processes, blood pressure, heart rate, renal output, reflexes, respiration, etc., in a patient or experimental animal; includes pharmacologic monitoring, the measurement of administered drugs or their metabolites in the blood, tissues, or urine.
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.
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.
Exercise
Electrocardiography
Recording of the moment-to-moment electromotive forces of the HEART as projected onto various sites on the body's surface, delineated as a scalar function of time. The recording is monitored by a tracing on slow moving chart paper or by observing it on a cardioscope, which is a CATHODE RAY TUBE DISPLAY.
Encyclopedias as Topic
Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)
Point-of-Care Systems
Biological Science Disciplines
All of the divisions of the natural sciences dealing with the various aspects of the phenomena of life and vital processes. The concept includes anatomy and physiology, biochemistry and biophysics, and the biology of animals, plants, and microorganisms. It should be differentiated from BIOLOGY, one of its subdivisions, concerned specifically with the origin and life processes of living organisms.