Cardiology diagnostic tests and procedures

The diagnostic tests in cardiology are methods of identifying heartconditions associated with healthy vs. unhealthy, pathologic, heartfunction.

Bedside

History

Obtaining a medical historyis always the first "test", part of understanding the likelihood of significant disease, as detectable within the current limitations of clinical medicine. Yet heart problems often produce no symptoms until very advanced, and many symptoms, such as palpitations and sensations of extra or missing heart beats correlate poorly with realtive heart health vs disease. Hence, a history alone is rarely sufficient to diagnose a heart condition.

Auscultation

Auscultation employs a stethoscopeto more easily hear various normal and abnormal sounds, such as normal heart beat sounds and the usual heart beat sound changes associated with breathing versus heart murmurs.

Laboratory

Blood tests

A variety of blood tests are available for analyzing cholesteroltransport behavior, HDL, LDL, triglycerides, lipoprotein little a, homocysteine, C-reactive protein, blood sugar control: fasting, after eating or averages using glycosylated albumen or hemoglobin, myoglobin, creatine kinase, troponin, brain-type natriuretic peptide, etc. to assess the evolution of coronary artery diseaseand evidence of existing damage. A great many more physiologicmarkers related to atherosclerosisand heartfunction are used and being developed and evaluated in research.

Electrophysiology

Electrocardiogram

Electrocardiography (ECG/EKG) monitors electricalactivity of the heart, primarily as recorded from the skin surface. A 12 lead recording, 6 for the front plane and 6 for the lower chest crossectional plane, is the most commonly used form.

Holter monitor

A Holter monitor records a continuous EKG rhythm pattern (rarely a full EKG) for 24 hours or more. These monitors are used for suspected frequent rhythm abnormalities, especially ones the wearer may not recognize by symptoms. They are more expensive than event monitors.

Event monitor

An Event monitor records short term EKG rhythm patterns, generally storing the last 2 to 5 minutes, adding in new & discarding old data, for 1 to 2 weeks or more. There are several different types with different capabilities. When the wearer presses a button on the monitor, it quits discarding old and continues recording for a short additional period. The wearer then plays the recording, via a standard phone connection, to a center with compatible receiving and rhythm printing equipment, after which the monitor is ready to record again. These monitors are used for suspected infrequent rhythm abnormalities, especially ones the wearer does recognize by symptoms. They are less expensive than Holter monitors.

Cardiac stress testing

Cardiac stress testing is used to determine to assess cardiac function and to disclose evidence of exertion-related cardiac hypoxia. Radionuclide testingusing thalliumor technetiumcan be used to demonstrate areas of perfusion abnormalities.

Medical imaging

Coronary catheterization

Coronary catheterization uses pressuremonitoring and blood sampling through a catheterinserted into the heartthrough blood vessels in the leg to determine the functioning of the heart, and, following injections of radiocontrast dye, uses X-ray fluoroscopy, typically at 30 frame/s, to visualize the position and size of blood of within the heartchambers and arteries. Coronary angiographyis used to determine the patency and configuration of the coronary arterylumens.

Echocardiogram

Echocardiography uses ultrasonicwaves for continuous heartchamber and bloodmovement visualization.

Intravascular ultrasound

Intravascular ultrasound, an imaging methodology using specially designed, long, thin, complex manufactured cathetersattached to computerized ultrasoundequipment to visualize the lumenand the interior wall of blood vessels.

Positron emission tomography

Positron emission tomography, an imaging methodology for positronemitting radioisotopes. PET enables visual image analysis of multiple different metabolic chemical processes and is thus one of the most flexible imaging technologies. Cardiology uses are growing very slowly due to technical and relative cost difficulties. Most uses are for research, not clinicalpurposes. Appropriate radioisotopesof elements within chemical compounds of the metabolicpathway being examined are used to make the location of the chemical compounds of interest visible in a PET scanner constructed image.

Computed axial tomography

Computed axial tomography, an imaging methodology using a ring-shaped machine with an X-Raysource spinning around the circular path so as to bathe the inner circle with a uniform and known X-Ray density. High sensitivity X-Ray detectors are kept positioned opposite the X-Ray source around the ring. Variations in the intensity of the received X-Rays, as sensed by the detectors, reflect the relative radiodensityvariations of objects within the circle. A high speed computer calculates a cross-sectional, tomographic, 2-dimensional image reflecting the relative anatomic radiodensityof structure within the circle and are best viewed on a monitor. They are also printed on film (though with significant loss of information). If the object being scanned is moved smoothly through the ring as the process continues, then a series of spiraling tomographic data is generated which can be used to compute a 3-dimensional image, viewable on a monitor. Thus this technique is commonly called spiral CT. Cardiology uses are growing. The principle difficulty with current implementations, for Cardiologyuses, is the difficulty of imaging the ever moving heartstructures. Electron beam tomography(EBT), provides much faster tomographic imaging; spiral CTtends to have better image quality but rotates too slowly, especially for smaller, more rapidly moving structures, such as the mid-section of the right coronary artery.

Magnetic resonance imaging

Magnetic resonance imaging (originally called nuclear magnetic resonance imaging), an imaging methodology based on aligning the spin axis of nuclei within moleculesof the object being visualized using both powerful superconducting magnetsand radio frequencysignalsand detectors. Cardiologyuses are growing, especially since MRI differentiates soft tissuesbetter than CT. The principle difficulty with current implementations, for Cardiologyuses, is the difficulty of imaging the ever moving heartstructures, more so than with CT because MRI is much slower.

See also

• Cardiology

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