Tag: Echocardiography

Echocardiography uses high-frequency sound waves (also called ultra- sound) to produce a moving image of your heart. The sound waves are introduced into your body through a handheld device called a trans- ducer. They bounce off the structures and ?uids in the heart and return as echoes through the transducer. The echoes are converted into images on a monitor.

Echocardiogram

Using different types of echocardiography, your doctor can see the size, shape, and contraction of the heart muscle; watch the heart valves work- ing; and see how blood is ?owing through your heart and arteries. Dur- ing one test, a two-dimensional mode looks at the heart’s structures and function to see a larger picture, including a cross section; and a form called Doppler echocardiography to assess blood ?ow within the heart and to identify abnormal ?ow patterns.
In conjunction with a stress test, the echocardiogram may show that the wall of the heart does not move as well after exercise, suggesting that part of the heart may not get suf?cient

blood flow during exercise. That lack of blood can impair the heart muscle’s ability to contract.

What to Expect

You can have an echocardiogram in a doctor’s of?ce or a hospital. You do not need to pre- pare in any special way. You will be asked to remove your clothes, and electrodes will be attached to your chest and back, as in the pro- cedure for an ECG (page 122). The techni- cian will spread a gel over your chest to help with transmission. He or she will move the transducer over your heart and chest, pressing ?rmly, and will ask you to lie in several differ- ent positions and breathe slowly, or hold your breath to improve the image. The entire pro- cedure will take 45 minutes to an hour.

What the Results Mean

You may have to wait several days for the full results of the echocardiogram. If the test doesn’t reveal anything unexpected, you may get the results by phone. The test will indicate to your doctor how the chambers or walls of your heart have been altered by conditions such as heart attack, high blood pressure, previous heart damage, or heart failure. If you have had echocardio- grams before, the doctor can compare the results of the tests to assess how effective treatment has been.
The test also allows the doctor to analyze the strength and nature of your heart’s pumping action, which he or she may describe in terms of the “ejection fraction.” A normal ejection fraction is about 55 to 65 per- cent, meaning that more than half of the blood in your left ventricle (the main pumping chamber) is squeezed out in a single heartbeat. If the percentage is signi?cantly lower, the echocardiogram can show where the pumping action is weakened—for example, it may reveal an area of the heart weakened by a heart attack. The test may be especially meaningful for genetic conditions that can pose the risk of sudden death—for example, hypertrophic cardiomyopathy, which is an abnor- mal thickness of a heart muscle segment commonly observed in young athletes who die suddenly.
The echocardiogram also reveals the condition of each of the four heart valves and how well they are working. The use of the Doppler mode shows in real time how blood passes through the valves, which can indicate the nature of a valve problem; for example, backward ?ow may indicate a leaky valve. The echocardiogram also gives information about the volume of circulating blood, which might be affected by treatments such as diuretics. The echocardiogram answers questions about how several factors are interacting on your heart, how treatment can be tailored to address a speci?c type of malfunction, and how best to maintain the heart’s ability to pump blood.

Transesophageal Echocardiography

Your doctor may order a transesophageal echocardiogram (TEE), a form of echocardiography that overcomes some of the limitations of a regular echocardiogram. As the name implies, a transesophageal echocardiogram involves threading a small probe (less than half an inch wide) down your esophagus (the tube from your throat to your stom- ach). Instead of viewing your heart through your chest wall, the trans- esophageal echocardiogram transmits images from within your esophagus, which is much closer to the heart. It may be necessary if your weight, body shape, or other considerations make conventional echocardiographic techniques less useful.
You should not eat after midnight on the day of the test. However, if the test needs to be done urgently, it is best not to have eaten for 4 hours so that you are less likely to feel nauseous or vomit. Discuss with your doctor any medications you are taking, and whether you should take them before the test.
The test will probably be done in a hospital. Because you will be given a sedative, you should make arrangements to get a ride home. First you will lie on a table and an intravenous (IV) line will be inserted into your arm to deliver a sedative. The technician will place electrodes on your chest
that will be hooked up to an electrocardiographic machine to monitor your heart rhythms through- out the test.
After numbing your throat with an anesthetic spray, the technician will gently insert a probe with the transducer at the end into your throat and down your esophagus. This part of the procedure is the most uncomfortable, and you may feel like gagging. Once the transducer is in place, you will not feel any pain. You will be partially awake for the pro- cedure, because you may be asked to hold your breath or strain as if you were having a bowel movement, which puts your heart under some pressure and may help reveal problems.
When the test is over, the transducer and IV will be removed and you will be disconnected from the electrocardiographic equipment. You may feel sleepy from the sedative, and the doctor will want to make sure that your heart rate and blood pressure are normal, so you may remain in the hospital for a few hours. Most often you will be advised to wait at least 2 hours before you eat or drink anything, because your throat may still be numb. After the anesthetic wears off, your throat may be sore for a day or two. It’s best not to drive for 24 hours, to be sure that the anes- thetic is entirely out of your system, so arrange for a ride home from the test.

As with other stress tests, an exercise echocardiogram shows how your heart functions when it is working harder. It is most often done to con- ?rm or rule out coronary artery disease. The moving image enables your doctor to see where blockages are occurring.
A stress echocardiogram may be done in a doctor’s of?ce or a hospi- tal. The test has two parts. First, the technician does a resting echocar- diogram (ultrasound of the heart) while you lie on a table. Then you get on a treadmill or a stationary bicycle and exercise until your heart is working to maximum. A second echocardiogram is done while your heart rate is still high. The test will show if there are any exer- cise-induced changes in your heart in the results of the echocardiogram. For example, in areas of the heart where the blood supply is limited because of obstructions of the blood vessels to the heart muscle, that area may not contract as well as it should. In another example, an exercise- induced abnormality not present when the heart is at rest suggests reversible blood ?ow abnormalities and the need for treatment to prevent a heart attack.

Chemical Stress Testing

If a disability (for example, arthritis, back trouble, or a stroke) prevents you from exercising for a stress test, your doctor can use intravenous medication to increase your heart rate combined with an imaging tech- nique such as echocardiography to see how your heart functions when it’s working harder. This method is called chemical or pharmacologic stress testing. The medications most commonly used are dobutamine, dipyridamole, or adenosine.
The drugs are administered so that your heart rate increases gradu- ally. If you are able to do some exercise, you may be asked to walk on a treadmill for a minute or so after the drug is injected. Trained medical assistants will monitor you throughout the test, and you should report any unusual symptoms. Dobutamine may cause a marked increase in blood pressure or an arrhythmia. Adenosine may cause a brief, passing slowing of the heart rate. Both adenosine and dipyridamole can cause wheezing and should be used cautiously, if at all, in people with asthma or chronic obstructive pulmonary disease. The drugs can be stopped at any time.
Preparation for a chemical stress test is similar to regular stress test- ing. You will be asked not to eat or drink anything for at least 3 hours before the test, in order to avoid nausea. If you take medications, be sure to talk to your doctor about what to do; you may need to stop tak- ing them for an interval before the test. If you have diabetes and take insulin, you will need speci?c instructions. If you have any history of asthma, bronchitis, or emphysema, tell your doctor, because some stress-inducing medications may be harmful to you.