The heart is a two-stage electrical pump that circulates blood throughout the body. The anatomy includes four chambers and four valves. For the heart to function normally, these structures need to be intact. The heart muscle needs to beat in a coordinated fashion so that blood flows in and out of each chamber in the proper direction.
An echocardiogram (echo=sound + card=heart + gram=drawing) is an ultrasound test that can evaluate the structures of the heart and the direction of blood flow within it. Technicians specially trained in echocardiography produce the images and videos, often using a special probe or transducer placed in various places on the chest wall, to view the heart from different directions. Cardiologists, or heart specialists, are trained to evaluate these images to assess heart function and report the results. The echocardiogram is just one of the many tests that can be done to evaluate heart anatomy and function.
An electrocardiogram (EKG, ECG) is the most common heart tracing done. Electrodes are placed on the chest wall and collect information about the electrical activity of the heart. Aside from the heartbeat rate and rhythm, the EKG can provide indirect evidence of blood flow within arteries to the heart muscle and the thickness of the heart muscle.
Cardiac catheterization is an invasive test performed by a cardiologist. A catheter is threaded into the coronary arteries (those arteries that supply the heart muscle with blood) through the femoral artery in the groin, the radial artery in the wrist, or the brachial artery in the elbow. The dye is injected into the coronary arteries looking for blockage. In some instances, the blockage can be corrected by balloon angioplasty, where a balloon is inflated at the level of blockage, re-establishing blood flow. A stent can be used to keep the artery open. This test can also assess the heart chambers and valves’ size and function and the major arteries and veins that enter and leave the heart.
What are the key points of echocardiography?
• Echocardiography (echo) is a painless test that uses sound waves to create pictures of your heart.
• This test gives your doctor information about your heart’s size and shape and how well your heart’s chambers and valves are working. Also, a type of echo called Doppler ultrasound shows how well blood flows through the chambers and valves of your heart.
• Your doctor may recommend an echo if you have signs and symptoms of heart problems. The test can be used to confirm a diagnosis, determine the status of an existing problem, or help guide treatment.
• There are several types of echo. Transthoracic and stress echo are standard types of the test. Transesophageal echo (TEE) is used if the standard tests don’t produce clear results. A fetal echo is used to look at an unborn baby’s heart. A three-dimensional (3D) echo may be used to help diagnose heart problems in children or plan and monitor heart valve surgery.
• Echo is done in a doctor’s office or hospital. The test usually takes up to an hour to do. A standard echo doesn’t require any special preparations or follow-up. If you have a TEE, you usually shouldn’t eat or drink for 8 hours before the test.
• During a standard echo, your doctor or sonographer will move a wand-like device called a transducer around on your chest to get pictures of your heart. During a TEE, the transducer will be put down your throat to get a better view of your heart.
• A cardiologist (heart specialist) will review the results from your echo.
• You usually can go back to your normal activities right after having an echo. If you have TEE, you may be watched for a few hours at the doctor’s office or hospital after the test.
• Transthoracic and fetal echo have no risks. If you have TEE, some risks are associated with the medicine given to help you relax. Rarely, the tube used in TEE can cause minor throat injuries. The risks for stress echo are related to the exercise or medicine used to raise your heart rate. Severe complications from stress echo are rare.
• Transthoracic echocardiogram: In the transthoracic echocardiogram procedure, the echocardiographer places the transducer, probe on the chest wall, and bounces sound waves off the structures of the heart. The same transducer received the return signals and converted by a computer into the images seen on the screen.
• Transesophageal echocardiogram: In some situations, a clearer view of the heart is required, and instead of placing the transducer on the chest wall, a cardiologist will direct the probe through the mouth into the esophagus. The esophagus is located right next to the heart in the middle of the chest. The sound waves can travel to the heart without interfering with the chest wall’s ribs and muscles.
○ This test usually requires intravenous medications to sedate the patient. The sedation monitors will also be used to measure blood pressure and oxygen levels in the blood.
• Doppler echocardiogram: In addition to sound waves bouncing off the heart’s solid structures, they also bounce off the red blood cells as they circulate through the heart chambers. Using Doppler technology, the echocardiogram can assess the speed and direction of blood flow, increasing the amount and quality of information available from the test. The computer can add color to help the doctor appreciate that information. Color flow Doppler is routinely added to all echocardiogram studies and is the same technology used in weather reports.
• Stress echocardiogram: A stress echocardiogram helps uncover abnormalities in the function of the heart wall muscle. The patient may be asked to exercise by either walking on a treadmill or riding an exercise bicycle. The echocardiogram is performed before exercise as a baseline and then immediately after the test.
• When coronary arteries narrow due to atherosclerotic heart disease, the heart muscle may not receive enough blood supply during exercise. During a stress echocardiogram, the heart muscle areas not receiving enough blood flow may not squeeze as well as other parts of the heart and will appear to have motion abnormality. This can indirectly indicate narrowing or stenosis of the coronary arteries. This can cause chest pain (angina), shortness of breath, or you may have no symptoms.
• For a stress echocardiogram to be effectively interpreted, the exercise done needs to achieve certain minimum intensity. Suppose the patient is unable to exercise adequately. In that case, medications can be injected intravenously to make the heart respond as if exercise is occurring chemically.
• Contrast may be injected into the patient’s vein to help enhance the images and increase the obtained information. The contrast material (Optison, Density) are microscopic protein shells filled with gas bubbles. The decision to use contrast depends upon the patient’s specific situation.
The purpose of an echocardiogram is to assess the structure and function of the heart. It is recommended as a noninvasive procedure as part of assessing the potential and established heart problems.
Regarding structure, the test can assess the heart’s general size, the size of the four heart chambers, and the appearance and function of the four heart valves. It can look at the heart’s two septa; the atrial septum separates the right and left atrium. The ventricular septum separates the right and left ventricles. It can also assess the pericardium (the sac that lines the heart) and the aorta.
Regarding function, the echocardiogram can determine how the heart valves open and close. It can evaluate whether the heart muscle squeezes appropriately and how efficiently. Cardiac output measures how much blood the heart pumps. Ejection fraction measures what percent of blood within the heart is pumped out to the body with each heartbeat. It can also measure how well the heart relaxes between beats when the heart fills for the next pump.
Some heart issues that the echocardiogram can help evaluate include the following:
• Heart valve disorders: Stenosis (narrowed), insufficiency or regurgitation (leaking), and endocarditis (infection of the valves)
• Abnormalities of the septum: Atrial septal defect, ventricular septal defect, and patent foramen ovale
• Wall motion abnormalities: Cardiomyopathy, atherosclerotic heart disease (also known as coronary artery disease), and trauma
• Diseases of the pericardium (the sac that lines the heart): This includes pericardial effusion (assessment of fluid in the pericardial sac)
There is no preparation for a transthoracic echocardiogram.
When a transesophageal echocardiogram is performed, the patient usually requires some sedation to tolerate the procedure. The stomach should be empty to prevent vomiting and aspiration into the lungs. For that reason, the patient should have nothing to eat or drink for many hours before the procedure. Due to the sedation, the patient will need a family member or friend to escort the patient home.
For a stress echocardiogram, the patient may need to walk on a treadmill or ride a bicycle. Comfortable shoes are recommended.
An echocardiogram is an office or outpatient procedure. Electrodes are placed on the chest wall to monitor heart rate and rhythm. The lights in the room may be dimmed to help see the images on the computer monitor. If contrast is used, an intravenous line will need to be started.
In a transthoracic echocardiogram, the patient’s chest will need to be exposed. The technician will press the transducer or probe firmly on the chest wall to get the heart images. The patient may be asked to roll on their left side take deep breaths to help the probe better “see” the heart. The patient will be monitored because of the need for intravenous sedation. A heart monitor and oxygen monitor will be placed; supplemental oxygen is usually provided by prongs placed in the nose. An intravenous line will be started. Once sedated, the cardiologist will pass a tube, with the transducer on its tip, through the mouth and position it in the esophagus at a level near the heart.
The patient may or may or remember the procedure because many sedative medicines have an amnestic effect. Still, once the patient is fully awake, they may be discharged home with an escort.
There are no risks associated with a transthoracic echocardiogram.
The risks of a transesophageal echocardiogram are due to the sedation required to perform the procedure or, very rarely, damage to the esophagus.
The purpose of the echocardiogram is to assess the structure and function of the heart. The results will provide information that can help the health care professional diagnose that involves the heart.
Echocardiograms may be repeated over time, monitoring heart function. The results may help decide whether a previous treatment has been effective and whether any treatment program changes are required.
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