Echocardiography
Echocardiography
Definition
Echocardiography is a diagnostic test that uses ultrasound waves to produce an image of the heart muscle and the heart's valves.
Purpose
Echocardiography is used to diagnose certain cardiovascular diseases, and is one of the most widely used
diagnostic tests for heart disease. Ultrasound waves that rebound or echo off the heart can show the size, shape, and movement of the heart's valves and chambers, as well as the flow of blood through the heart. Echocardiography may show abnormalities such as a poorly functioning heart valve or damage to the heart tissue from a heart attack. Echocardiography is especially useful for assessing disorders of the heart valves. It not only allows doctors to evaluate the heart valves, but can also detect abnormalities in the pattern of blood flow. For example, echocardiography can show the backward flow of blood through partially open heart valves (that should be fully closed). This backward flow of blood through a valve is known as regurgitation. By assessing the motion of the heart wall, echocardiography can help detect the presence and assess the severity of coronary artery disease , as well as help determine whether chest pain is related to heart disease. Additionally, echocardiography can help detect hypertrophic cardiomyopathy, in which the walls of the heart thicken in an attempt to compensate for heart muscle weakness.
Echocardiography is also used to evaluate heart murmurs (abnormal heart sounds), determine the causes of congestive heart failure , assess enlarged hearts or hearts with septal defects (holes between pumping chambers), and to monitor the heart in patients with diseases that may affect heart function (e.g., lupus, lung diseases). The biggest advantage to echocardiography is that it is noninvasive (it doesn't involve breaking the skin or entering body cavities) and has no known risks or side effects. Echocardiography is often used in conjunction with other diagnostic tests for the heart, such as electrocardiography .
Echocardiography is usually performed in the cardiology department at a hospital, but may also be performed in a cardiologist's office or an outpatient imaging center. Because the ultrasound scanners used to perform echocardiography are portable (handheld) or mobile, echocardiography can be performed in the emergency department or at the bedside of patients who cannot be transported to the cardiology department.
Precautions
Echocardiography is a safe, noninvasive procedure, and there are no special precautions.
Description
Echocardiography creates an image of the heart using ultra-high-frequency sound waves—sound waves that are too high in frequency to be heard by the human ear. The technique is very similar to ultrasound scanning commonly used to visualize the fetus during pregnancy .
An echocardiography examination generally lasts between 15-30 minutes. The patient lies bare-chested on an examination table. A special gel is spread over the chest to help the transducer make good contact and slide smoothly over the skin. The transducer, also called a probe, is a small handheld device at the end of a flexible cable. The transducer, essentially a modified microphone, is placed against the chest and directs ultrasound waves into the chest. Some of the waves get echoed (or reflected) back to the transducer. Since different tissues and blood reflect ultrasound waves differently, these sound waves can be translated into a meaningful image of the heart that can be displayed on a monitor or recorded on paper or tape. The patient does not feel the sound waves, and the entire procedure is painless.
Occasionally, variations of the echocardiography test are used. For example, Doppler echocardiography employs a special microphone that allows technicians to measure and analyze the direction and speed of blood flow through blood vessels and heart valves. This makes it especially useful for detecting and evaluating regurgitation through the heart valves. By assessing the speed of blood flow at different locations around an obstruction, it can also help to precisely locate the obstruction.
An exercise echocardiogram, or stress echo, is an echocardiogram performed during exercise, when the heart muscle must work harder to supply blood to the body. This allows doctors to detect heart problems that might not be evident when the body is at rest and needs less blood. For patients who are unable to exercise, certain drugs can be used to mimic the effects of exercise by dilating the blood vessels and making the heart beat faster.
During the examination the sonographer can take measurements and, using the ultrasound scanner's computer, make calculations, including calculating blood flow speed. Most ultrasound scanners are equipped with videotape recorders or digital imaging/archiving devices to record the real-time examination, and with medical image printers to print out hard copies of still images.
Preparation
The patient removes any clothing and jewelry above the chest.
Aftercare
No special measures need to be taken following echocardiography.
Complications
There are no known complications associated with the use of echocardiography. There is a slight risk of having a heart attack during an exercise echocardiogram, due to the stress put on the heart during the test, mostly for patients with a history of heart attack or other risk factors.
Results
A normal echocardiogram shows a normal heart structure and the normal flow of blood through the heart chambers and heart valves. However, a normal echocardiogram does not rule out the possibility of heart disease.
An echocardiogram may show a number of abnormalities in the structure and function of the heart, such as:
- thickening of the wall of the heart muscle (especially the left ventricle)
- abnormal motion of the heart muscle
- blood leaking backward through the heart valves (regurgitation)
- decreased blood flow through a heart valve (stenosis)
Health care team roles
Echocardiography should be performed by a registered diagnostic cardiac sonographer—an ultrasonographer specially trained in cardiac ultrasound. The results should be interpreted by a cardiologist trained in the application of cardiac sonography. The Intersocietal Commission for the Accreditation of Echocardiography Laboratories provides a self-evaluation process for echocardiography labs to become accredited. Accreditation involves staff evaluation and training, equipment assessment, and peer review.
KEY TERMS
Doppler imaging —A mode of ultrasound imaging that uses the physics principle of the Doppler effect (sound frequency waves shift relative to the observer, allowing velocity measurement) to produce color or gray-scale images of blood flow velocity and heart motion.
Heart murmur —An abnormal sound originating from the heart, usually detected by stethoscope. Murmurs are often caused by abnormalities of the heart valves.
Lupus —Also known as systemic lupus erythematosus, it is an autoimmune disease that may affect connective tissues and possibly the heart.
Noninvasive —Pertaining to a diagnostic procedure or treatment that does not require the skin to be broken or a body cavity to be entered.
Regurgitation —Backward flow of blood through a partially closed heart valve.
Transducer —A device that converts electrical signals into ultrasound waves and ultrasound waves back into electrical impulses; also called a probe.
Ultrasound —Sound waves at high frequencies beyond the level of human hearing; frequencies of approximately 2 to 10 megahertz are often used for diagnostic ultrasound imaging.
Resources
BOOKS
Faculty Members of the Yale University School of Medicine. The Patient's Book of Medical Tests. Boston, New York: Houghton Mifflin Company, 1997.
PERIODICALS
Kosoff, George. "Basic Physics and Imaging Characteristics of Ultrasound." World Journal of Surgery 24 (February 2000):134-142.
Lee, Thomas H. and Charles A. Boucher. "Noninvasive tests in patients with stable coronary artery disease." New England Journal of Medicine 344, no. 24 (June 14,2001):1840-6.
ORGANIZATIONS
American College of Cardiology. Heart House, 9111 Old Georgetown Road, Bethesda, MD 20814-1699. (800) 253-4636. <http://www.acc.org>.
American Heart Association National Center. 7272 Greenville Avenue, Dallas, Texas 75231. (800) AHA-USA1. <http://www.americanheart.org>.
American Institute of Ultrasound in Medicine. 14750 Sweitzer Lane, Suite 100, Laurel, MD 20707-5906. (301) 498-4100. <http://www.aium.org>.
American Registry of Diagnostic Medical Sonographers. 600 Jefferson Plaza, Suite 360, Rockville, MD 20852-1150.(800) 541-9754. <http://www.ardms.org>.
American Society of Echocardiography. 1500 Sunday Drive, Suite 102, Raleigh, NC 27607. (919) 787-5181. <http://asecho.org>.
OTHER
Barasch, Eddy. "Why Doctors Use Echocardiography." <http://www.thedoctorwillseeyounow.com/articles/heart/echocard_3/>.
Jennifer E. Sisk, M.A.
Echocardiography
Echocardiography
Definition
Echocardiography is a diagnostic test that uses ultrasound waves to produce an image of the heart muscle and the heart's valves.
Purpose
Echocardiography is used to diagnose certain cardiovascular diseases, and is one of the most widely used diagnostic tests for heart disease. Ultrasound waves that rebound or echo off the heart can show the size, shape, and movement of the heart's valves and chambers, as well as the flow of blood through the heart. Echocardiography may show abnormalities such as a poorly functioning heart valve or damage to the heart tissue from a heart attack. Echocardiography is especially useful for assessing disorders of the heart valves. It not only allows doctors to evaluate the heart valves, but can also detect abnormalities in the pattern of blood flow. For example, echocardiography can show the backward flow of blood through partially open heart valves (that should be fully closed). This backward flow of blood through a valve is known as regurgitation. By assessing the motion of the heart wall, echocardiography can help detect the presence and assess the severity of coronary artery disease, as well as help determine whether chest pain is related to heart disease. Additionally, echocardiography can help detect hypertrophic cardiomyopathy, in which the walls of the heart thicken in an attempt to compensate for heart muscle weakness.
Echocardiography is also used to evaluate heart murmurs (abnormal heart sounds), determine the causes of congestive heart failure, assess enlarged hearts or hearts with septal defects (holes between pumping chambers), and to monitor the heart in patients with diseases that may affect heart function (e.g., lupus, lung diseases). The biggest advantage to echocardiography is that it is noninvasive (it doesn't involve breaking the skin or entering body cavities) and has no known risks or side effects. Echocardiography is often used in conjunction with other diagnostic tests for the heart, such as electrocardiography.
Echocardiography is usually performed in the cardiology department at a hospital, but may also be performed in a cardiologist's office or an outpatient imaging center. Because the ultrasound scanners used to perform echocardiography are portable (handheld) or mobile, echocardiography can be performed in the emergency department or at the bedside of patients who cannot be transported to the cardiology department.
Precautions
Echocardiography is a safe, noninvasive procedure, and there are no special precautions.
Description
Echocardiography creates an image of the heart using ultra-high-frequency sound waves—sound waves that are too high in frequency to be heard by the human ear. The technique is very similar to ultrasound scanning commonly used to visualize the fetus during pregnancy.
An echocardiography examination generally lasts between 15-30 minutes. The patient lies bare-chested on an examination table. A special gel is spread over the chest to help the transducer make good contact and slide smoothly over the skin. The transducer, also called a probe, is a small handheld device at the end of a flexible cable. The transducer, essentially a modified microphone, is placed against the chest and directs ultrasound waves into the chest. Some of the waves get echoed (or reflected) back to the transducer. Since different tissues and blood reflect ultrasound waves differently, these sound waves can be translated into a meaningful image of the heart that can be displayed on a monitor or recorded on paper or tape. The patient does not feel the sound waves, and the entire procedure is painless.
Occasionally, variations of the echocardiography test are used. For example, Doppler echocardiography employs a special microphone that allows technicians to measure and analyze the direction and speed of blood flow through blood vessels and heart valves. This makes it especially useful for detecting and evaluating regurgitation through the heart valves. By assessing the speed of blood flow at different locations around an obstruction, it can also help to precisely locate the obstruction.
An exercise echocardiogram, or stress echo, is an echocardiogram performed during exercise, when the heart muscle must work harder to supply blood to the body. This allows doctors to detect heart problems that might not be evident when the body is at rest and needs less blood. For patients who are unable to exercise, certain drugs can be used to mimic the effects of exercise by dilating the blood vessels and making the heart beat faster.
During the examination the sonographer can take measurements and, using the ultrasound scanner's computer, make calculations, including calculating blood flow speed. Most ultrasound scanners are equipped with videotape recorders or digital imaging/archiving devices to record the real-time examination, and with medical image printers to print out hard copies of still images.
Preparation
The patient removes any clothing and jewelry above the chest.
Aftercare
No special measures need to be taken following echocardiography.
Complications
There are no known complications associated with the use of echocardiography. There is a slight risk of having a heart attack during an exercise echocardiogram, due to the stress put on the heart during the test, mostly for patients with a history of heart attack or other risk factors.
Results
A normal echocardiogram shows a normal heart structure and the normal flow of blood through the heart chambers and heart valves. However, a normal echocardiogram does not rule out the possibility of heart disease.
An echocardiogram may show a number of abnormalities in the structure and function of the heart, such as:
- thickening of the wall of the heart muscle (especially the left ventricle)
- abnormal motion of the heart muscle
- blood leaking backward through the heart valves (regurgitation)
- decreased blood flow through a heart valve (stenosis)
Health care team roles
Echocardiography should be performed by a registered diagnostic cardiac sonographer—an ultrasonographer specially trained in cardiac ultrasound. The results should be interpreted by a cardiologist trained in the application of cardiac sonography. The Intersocietal Commission for the Accreditation of Echocardiography Laboratories provides a self-evaluation process for echocardiography labs to become accredited. Accreditation involves staff evaluation and training, equipment assessment, and peer review.
KEY TERMS
Doppler imaging— A mode of ultrasound imaging that uses the physics principle of the Doppler effect (sound frequency waves shift relative to the observer, allowing velocity measurement) to produce color or gray-scale images of blood flow velocity and heart motion.
Heart murmur— An abnormal sound originating from the heart, usually detected by stethoscope. Murmurs are often caused by abnormalities of the heart valves.
Lupus— Also known as systemic lupus erythematosus, it is an autoimmune disease that may affect connective tissues and possibly the heart.
Noninvasive— Pertaining to a diagnostic procedure or treatment that does not require the skin to be broken or a body cavity to be entered.
Regurgitation— Backward flow of blood through a partially closed heart valve.
Transducer— A device that converts electrical signals into ultrasound waves and ultrasound waves back into electrical impulses; also called a probe.
Ultrasound— Sound waves at high frequencies beyond the level of human hearing; frequencies of approximately 2 to 10 megahertz are often used for diagnostic ultrasound imaging.
Resources
BOOKS
Faculty Members of the Yale University School of Medicine. The Patient's Book of Medical Tests. Boston, New York: Houghton Mifflin Company, 1997.
PERIODICALS
Kosoff, George. "Basic Physics and Imaging Characteristics of Ultrasound." World Journal of Surgery 24 (February 2000):134-142.
Lee, Thomas H. and Charles A. Boucher. "Noninvasive tests in patients with stable coronary artery disease." New England Journal of Medicine 344, no. 24 (June 14, 2001):1840-6.
ORGANIZATIONS
American College of Cardiology. Heart House, 9111 Old Georgetown Road, Bethesda, MD 20814-1699. (800) 253-4636. 〈http://www.acc.org〉.
American Heart Association National Center. 7272 Greenville Avenue, Dallas, Texas 75231. (800) AHA-USA1. 〈http://www.americanheart.org〉.
American Institute of Ultrasound in Medicine. 14750 Sweitzer Lane, Suite 100, Laurel, MD 20707-5906. (301) 498-4100. 〈http://www.aium.org〉.
American Registry of Diagnostic Medical Sonographers. 600 Jefferson Plaza, Suite 360, Rockville, MD 20852-1150. (800) 541-9754. 〈http://www.ardms.org〉.
American Society of Echocardiography. 1500 Sunday Drive, Suite 102, Raleigh, NC 27607. (919) 787-5181. 〈http://asecho.org〉.
OTHER
Barasch, Eddy. "Why Doctors Use Echocardiography." 〈http://www.thedoctorwillseeyounow.com/articles/heart/echocard_3/〉.
Echocardiography
Echocardiography
Definition
Purpose
Description
Preparation
Aftercare
Risks
Normal results
Definition
Echocardiography is a noninvasive diagnostic test that uses ultrasound waves to produce an moving image of the heart.
Purpose
Echocardiography is one of the most widely used diagnostic tests for heart disease. Ultrasound waves generated by a device placed on the skin rebound or echo off the heart and are processed by a computer. The resulting image can show the size, shape, and movement of the heart’s valves and chambers, as well as the flow of blood through the heart.
Echocardiography may reveal abnormalities such damage to the heart tissue from a heart attack or as a poorly functioning heart valve. Echocardiography is especially useful for assessing disorders of the heart valves. It not only allows doctors to evaluate the condition of the heart valves, but also can show abnormalities in the pattern of blood flow. For example, echocardiography can show the backward flow of blood through heart valves that remain partially open and should be fully closed.
By assessing the motion of the heart wall, echocardiography can help detect the presence and assess the severity of coronary artery disease, as well as help determine whether chest pain is related to heart disease. Additionally, echocardiography can help detect hypertrophic cardiomyopathy, a condition in which
the walls of the heart thicken in an attempt to compensate for heart muscle weakness.
Echocardiography is also used to evaluate heart murmurs (abnormal heart sounds), determine the causes of congestive heart failure, assess enlarged hearts, hearts with septal defects (holes between pumping chambers), and to monitor the heart in patients with diseases that may affect heart function (e.g., lupus erythematosus, lung diseases). The biggest advantage to echocardiography is that it is noninvasive (it does not involve breaking the skin or entering body cavities), and it has no known risks or side effects. It also gives a more detailed picture of the heart than other imaging techniques. Echocardiography is often used in conjunction with other diagnostic tests for the heart such as electrocardiography.
Echocardiography is usually performed in the cardiology department at a hospital, but may also be performed in a cardiologist’s office or an outpatient imaging center. Because the ultrasound scanners used to perform echocardiography are portable (handheld) or mobile, echocardiography can be performed in a hospital emergency department or at the bedside of patients who cannot be moved.
Description
Echocardiography creates an image of the heart using ultra-high-frequency sound waves—sound waves that are too high in frequency to be heard by the human ear. The technique is very similar to ultrasound scanning commonly used to visualize the fetus during pregnancy.
An echocardiography examination generally lasts 15-30 minutes. The patient lies bare-chested on an examination table. A special gel is spread over the chest to help the transducer make good contact and to slide smoothly over the skin. The transducer, also called a probe, is a small handheld device at the end of a flexible cable. The transducer is placed against the chest and directs ultrasound waves into the chest. Some of the waves get echoed (or reflected) back to the transducer. Since different tissues and blood reflect ultrasound waves differently, these returning sound waves can be translated into a meaningful image of the heart that is displayed on a monitor and recorded. The patient does not feel the sound waves, and the entire procedure is painless.
Occasionally, variations of the echocardiography test are used. For example, Doppler echocardiography employs a special transducer that allows technicians to measure and analyze the direction and speed of blood flow through blood vessels and heart valves. This makes it especially useful for detecting and evaluating backflow through the heart valves. By assessing the speed of blood
KEY TERMS
Lupus erythematosus— A chronic autoimmune disease that affects the skin, joints, and certain internal organs.
flow at different locations around an obstruction, it can also help to precisely locate the obstruction.
An exercise echocardiogram, or stress echo, is an echocardiogram performed during exercise, when the heart muscle must work harder to supply blood to the body. This allows doctors to detect heart problems that might not be evident when the body is at rest and needs less blood. For patients who are unable to exercise, certain drugs can be used to mimic the effects of exercise by dilating the blood vessels and making the heart beat faster.
A transesophageal is done when it is difficult to get a clear picture of the heart using standard electrocardiogram techniques (e.g., interference from internal scar tissue, obesity). A transducer is attached to an endoscope, a thin tube that is threaded down the throat after it has been numbed. This position allows a clearer picture of the heart.
During the examination, a trained sonographer takes measurements and, using the ultrasound scanner’s computer, make calculations, including measuring blood flow speed. Most ultrasound scanners are equipped with videotape recorders or digital imaging/ archiving devices to record the real-time examination, and with medical image printers to print out hard copies of still images. Information from the echocardiogram is then evaluated by a cardiologist.
Preparation
The patient removes any clothing and jewelry above the waist.
Aftercare
No special measures need to be taken following echocardiography. The procedure is painless.
Risks
There are no known complications associated with the use of echocardiography. There is a slight risk of having a heart attack during an exercise echocardiogram, due to the stress put on the heart during the test, mostly for patients with a history of heart attack or other risk factors.
Normal results
A normal echocardiogram shows a normal heart structure and the normal flow of blood through the heart chambers and heart valves. However, a normal echocardiogram does not rule out the possibility certain types of heart disease.
An echocardiogram may show a number of abnormalities in the structure and function of the heart, including:
- thickening of the wall of the heart muscle (especially the left ventricle)
- abnormal motion of the heart muscle
- blood leaking backward through the heart valves
- decreased blood flow through a heart valve due to narrowing of the valve (stenosis)
Resources
ORGANIZATIONS
American College of Cardiology. Heart House. 2400 N Street, NW | Washington, DC 20037. (202) 375-6000. http://www.acc.org (accessed March 19, 2008).
American Heart Association. 7272 Greenville Avenue, Dallas, TX 75231. (800) 242-8721. http://www.americanheart.org (accessed March 19, 2008).
American Registry of Diagnostic Medical Sonographers. 51 Monroe Street, Plaza One East, Rockville, MD 20850. (800) 541-9754. http://www.ardms.org (accessed March 19, 2008).
American Society of Echocardiography. 1500 Sunday Drive, Suite 102, Raleigh, NC 27607. (919) 861-5574. http://www.asecho.org (accessed March 19, 2008).
OTHER
“Echocardiogram.” Medline Plus April 12, 2007 [cited January 4, 2008]. http://www.nlm.nih.gov/medlineplus/ency/article/003869.htm (accessed March 19, 2008).
“Echocardiogram: Sound Imaging of the Heart.” Mayo Clinic July 14, 2006 [cited January 4, 2008]. http://www.mayoclinic.com/health/echocardiogram/HB00012 (accessed March 19, 2008).
Jennifer E. Sisk, MA
Lee Shratter, MD
Tish Davidson, AM
Ectopic pregnancy treatment seeSalpingostomy
EECP seeEnhanced external counterpulsation
EEG seeElectroencephalography
EKG seeElectrocardiography
Elective abortion seeAbortion, induced
Echocardiography
Echocardiography
Definition
Echocardiography is a diagnostic test that uses ultrasound waves to create an image of the heart muscle. Ultrasound waves that rebound or echo off the heart can show the size, shape, and movement of the heart's valves and chambers as well as the flow of blood through the heart. Echocardiography may show such abnormalities as poorly functioning heart valves or damage to the heart tissue from a past heart attack.
Purpose
Echocardiography is used to diagnose certain cardiovascular diseases. In fact, it is one of the most widely used diagnostic tests for heart disease. It can provide a wealth of helpful information, including the size and shape of the heart, its pumping strength, and the location and extent of any damage to its tissues. It is especially useful for assessing diseases of the heart valves. It not only allows doctors to evaluate the heart valves, but it can detect abnormalities in the pattern of blood flow, such as the backward flow of blood through partly closed heart valves, known as regurgitation. By assessing the motion of the heart wall, echocardiography can help detect the presence and assess the severity of coronary artery disease, as well as help determine whether any chest pain is related to heart disease. Echocardiography can also help detect hypertrophic cardiomyopathy, in which the walls of the heart thicken in an attempt to compensate for heart muscle weakness. The biggest advantage to echocardiography is that it is noninvasive (does not involve breaking the skin or entering body cavities) and has no known risks or side effects.
Precautions
Echocardiography is an extremely safe procedure and no special precautions are required.
Description
Echocardiography creates an image of the heart using ultra-high-frequency sound waves-sound waves that are too high in frequency to be heard by the human ear. The technique is very similar to ultrasound scanning commonly used to visualize the fetus during pregnancy.
An echocardiography examination generally lasts between 15-30 minutes. The patient lies bare-chested on an examination table. A special gel is spread over the chest to help the transducer make good contact and slide smoothly over the skin. The transducer, a small hand-held device at the end of a flexible cable, is placed against the chest. Essentially a modified microphone, the transducer directs ultrasound waves into the chest. Some of the waves get echoed (or reflected) back to the transducer. Since different tissues and blood all reflect ultrasound waves differently, these sound waves can be translated into a meaningful image of the heart, which can be displayed on a monitor or recorded on paper or tape. The patient does not feel the sound waves, and the entire procedure is painless. In fact, there are no known side effects.
Occasionally, variations of the echocardiography test are used. For example, Doppler echocardiography employs a special microphone that allows technicians to measure and analyze the direction and speed of blood flow through blood vessels and heart valves. This makes it especially useful for detecting and evaluating regurgitation through the heart valves. By assessing the speed of blood flow at different locations around an obstruction, it can also help to precisely locate the obstruction.
An exercise echocardiogram is an echocardiogram performed during exercise, when the heart muscle must work harder to supply blood to the body. This allows doctors to detect heart problems that might not be evident when the body is at rest and needs less blood. For patients who are unable to exercise, certain drugs can be used to mimic the effects of exercise by dilating the blood vessels and making the heart beat faster.
Preparation
The patient removes any clothing and jewelry above the chest.
Aftercare
No special measures need to be taken following echocardiography.
Risks
There are no known risks associated with the use of echocardiography.
Normal results
A normal echocardiogram shows a normal heart structure and the normal flow of blood through the heart chambers and heart valves. However, a normal echocardiogram does not rule out the possibility of heart disease.
Abnormal results
An echocardiogram may show a number of abnormalities in the structure and function of the heart, such as:
- thickening of the wall of the heart muscle (especially the left ventricle)
- abnormal motion of the heart muscle
- blood leaking backward through the heart valves (regurgitation)
- decreased blood flow through a heart valve (stenosis)
Resources
ORGANIZATIONS
American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. 〈http://www.americanheart.org〉.
National Heart, Lung and Blood Institute. PO Box 30105, Bethesda, MD 20824-0105. (301) 251-1222. 〈http://www.nhlbi.nih.gov〉.
KEY TERMS
Noninvasive— Pertaining to a diagnostic procedure or treatment that does not require the skin to be broken or a body cavity to be entered.
Regurgitation— Backward flow of blood through a partly closed heart valve.
Transducer— A device that converts electrical signals into ultrasound waves and ultrasound waves back into electrical impulses.
Ultrasound— Sound waves at a frequency of over 20,000 kHz, often used for diagnostic imaging.
Echocardiography
Echocardiography
Definition
Echocardiography is a diagnostic test that uses ultrasound waves to produce an image of the heart muscle and the heart's valves.
Purpose
Echocardiography is used to diagnose certain cardiovascular diseases, and is one of the most widely used diagnostic tests for heart disease. Ultrasound waves that rebound or echo off the heart can show the size, shape, and movement of the heart's valves and chambers, as well as the flow of blood through the heart. Echocardiography may show abnormalities such as a poorly functioning heart valve or damage to the heart tissue from a heart attack. Echocardiography is especially useful for assessing disorders of the heart valves. It not only allows doctors to evaluate the heart valves, but can also detect abnormalities in the pattern of blood flow. For example, echocardiography can show the backward flow of blood through heart valves that are partially open (that should be fully closed). This backward flow of blood through a valve is known as regurgitation. By assessing the motion of the heart wall, echocardiography can help detect the presence, and assess the severity, of coronary artery disease, as well as help determine whether chest pain is related to heart disease. Additionally, echocardiography can help detect hypertrophic cardiomyopathy, in which the walls of the heart thicken in an attempt to compensate for heart muscle weakness.
Echocardiography is also used to evaluate heart murmurs (abnormal heart sounds), determine the causes of congestive heart failure, assess enlarged hearts or hearts with septal defects (holes between pumping chambers), and monitor the heart in patients with diseases that may affect heart function (e.g., lupus, lung diseases). The biggest advantage to echocardiography is that it is noninvasive (it does not involve breaking the skin or entering body cavities) and has no known risks or side effects. Echocardiography is often used in conjunction with other diagnostic tests for the heart such as electrocardiography .
Echocardiography is usually performed in the cardiology department at a hospital, but may also be performed in a cardiologist's office or an outpatient imaging center. Because the ultrasound scanners used to perform echocardiography are portable (handheld) or mobile, echocardiography can be performed in the hospital's emergency department or at the bedside of patients who cannot be transported to the cardiology department.
Description
Echocardiography creates an image of the heart using ultra-high-frequency sound waves—sound waves that are too high in frequency to be heard by the human ear. The technique is very similar to ultrasound scanning commonly used to visualize the fetus during pregnancy.
An echocardiography examination generally lasts between 15–30 minutes. The patient lies bare-chested on an examination table. A special gel is spread over the chest to help the transducer make good contact and slide smoothly over the skin. The transducer, also called a probe, is a small handheld device at the end of a flexible cable. The transducer, essentially a modified microphone, is placed against the chest and directs ultrasound waves into the chest. Some of the waves get echoed (or reflected) back to the transducer. Since different tissues and blood reflect ultrasound waves differently, these sound waves can be translated into a meaningful image of the heart that can be displayed on a monitor or recorded on paper or tape. The patient does not feel the sound waves, and the entire procedure is painless.
Occasionally, variations of the echocardiography test are used. For example, Doppler echocardiography employs a special microphone that allows technicians to measure and analyze the direction and speed of blood flow through blood vessels and heart valves. This makes it especially useful for detecting and evaluating regurgitation through the heart valves. By assessing the speed of blood flow at different locations around an obstruction, it can also help to precisely locate the obstruction.
An exercise echocardiogram, or stress echo, is an echocardiogram performed during exercise, when the heart muscle must work harder to supply blood to the body. This allows doctors to detect heart problems that might not be evident when the body is at rest and needs less blood. For patients who are unable to exercise, certain drugs can be used to mimic the effects of exercise by dilating the blood vessels and making the heart beat faster.
During the examination the sonographer can take measurements and, using the ultrasound scanner's computer, make calculations, including measuring blood flow speed. Most ultrasound scanners are equipped with videotape recorders or digital imaging/archiving devices to record the real-time examination, and with medical image printers to print out hard copies of still images.
Preparation
The patient removes any clothing and jewelry above the chest.
Aftercare
No special measures need to be taken following echocardiography.
Risks
There are no known complications associated with the use of echocardiography. There is a slight risk of having a heart attack during an exercise echocardiogram, due to the stress put on the heart during the test, mostly for patients with a history of heart attack or other risk factors.
Normal results
A normal echocardiogram shows a normal heart structure and the normal flow of blood through the heart chambers and heart valves. However, a normal echocardiogram does not rule out the possibility of heart disease.
An echocardiogram may show a number of abnormalities in the structure and function of the heart, including:
- thickening of the wall of the heart muscle (especially the left ventricle)
- abnormal motion of the heart muscle
- blood leaking backward through the heart valves (regurgitation)
- decreased blood flow through a heart valve (stenosis)
Resources
books
the patient's book of medical tests. boston, new york city: houghton mifflin company, 1997.
periodicals
kosoff, george. "basic physics and imaging characteristics of ultrasound." world journal of surgery 24 (february 2000): 134–142.
lee, thomas h., and charles a. boucher. "noninvasive tests in patients with stable coronary artery disease." new england journal of medicine 344, no. 24 (june 14, 2001): 1840–6.
organizations
american college of cardiology. heart house. 9111 old georgetown road, bethesda, md 20814-1699. (800) 253-4636. <http://www.acc.org>.
american heart association national center. 7272 greenville avenue, dallas, tx 75231. (800) aha-usa1. <http://www.americanheart.org>.
american institute of ultrasound in medicine. 14750 sweitzer lane, suite 100, laurel, md 20707-5906. (301) 498-4100. <http://www.aium.org>.
american registry of diagnostic medical sonographers. 600 jefferson plaza, suite 360, rockville, md 20852-1150. (800) 541-9754. <http://www.ardms.org>.
american society of echocardiography. 1500 sunday drive, suite 102, raleigh, nc 27607. (919) 787-5181. <http://asecho.org>.
other
barasch, eddy. "why doctors use echocardiography." <http://www.thedoctorwillseeyounow.com/articles/heart/echo card_3/>.
Jennifer E. Sisk, MA Lee Shratter, MD
echocardiography
The method involves two basic elements, a transmitter and a receiver. The transmitter emits an electrical signal to a piezo-electric crystal each time an oscillation is required. The electrical signal is converted by the crystal to an ultrasound wave. The ultrasound beam is directed through the chest and the sound wave is transmitted and reflected as internal structures of the chest are encountered. The reflected waves are collected by the receiver. Currently, most echocardiographers use sector scanners to produce images of the heart. With these instruments the ultrasound beam is swept in an arc across the heart from a single point on the chest wall. The solid parts of the heart walls and even the very thin valves produce strong reflections, whereas blood-filled spaces produce little reflection and so are reported as ‘empty’ by ultrasound. The received pattern of sound waves is often displayed in a video format, but a permanent record can be produced by using photography or chart recorder technology. Since the time between the emission and reception of an ultrasound signal can be accurately measured, it is possible to display the depth at which a structure lies within the chest using a simple formula: D = V × T or, distance = (velocity of the ultrasound signal) × (time between emission and reception of the signal). In this way, an image of a ‘section’ of the heart can be built up over a number of cycles. Cross-sectional images can be produced by electronic sector scanners which have small multi-element transducers cut from the same piezo-electric crystals.
The narrowing (stenosis) of heart valves is a typical clinical problem that can be studied by echocardiography. In association with valve narrowing, the speed of blood flow and chamber dimensions are increased. By applying the Bernoulli principle it is possible to estimate the pressure differences across a damaged valve. Cardiac output can be assessed by measuring the velocity of blood flow leaving the heart and multiplying this by the echocardiographically-derived cross-sectional area of the aorta.
Doppler imaging, usually performed at the same time as echocardiography, utilizes the principal of the Doppler shift of ultrasound to measure velocity of blood flow in the chambers of the heart and in the aorta. In the ‘continuous wave Doppler’ technique, two piezo-electric crystals are utilized; one continually sends and another continually receives the ultrasound wave. Information is thus received from the entire length of the beam and range resolution is not possible. Its great advantage, however, is that high maximal velocities of blood flow, such as occur when blood is being ejected from the ventricles, can be reliably measured. In the pulsed Doppler system, the transmitter is turned off after sending the pulse to the crystal, while the receiver is immediately turned on. The receiver waits for the pressure wave-front to return to the crystal and amplifies it to allow frequency analysis. This technique is useful for localizing high velocity flow, as commonly associated with defective ventricular exit (aortic and pulmonary) valves, rather than for measuring an absolute velocity.
The current uses of cross-sectional and Doppler echocardiography are to record the dimensions of heart structures, cardiac output, jet velocities, and flow disturbances. Abnormal flow patterns can also be recorded and used, for example, to map jets of blood leaking from damaged valves. Recent technology has allowed colour coding of blood flow direction using a combination of cross-sectional and Doppler echocardiography.
David J. Miller, and Niall G. MacFarlane
See also heart; imaging techniques.
echocardiography
ech·o·car·di·og·ra·phy / ˌekōˌkärdēˈägrəfē/ • n. Med. the use of ultrasound waves to investigate the action of the heart.DERIVATIVES: ech·o·car·di·o·graph / -ˈkärdēəˌgraf/ n.ech·o·car·di·o·graph·ic / -ˌkärdēəˈgrafik/ adj.