An echocardiogram is a noninvasive imaging study for examining the heart’s position and size, movements of the valves and chamber, and velocity of blood flow. Echoes from pulsed high-frequency sound waves are used to locate and study the movements and dimensions of cardiac structures. Because the heart is a blood-filled organ, sound can be transmitted through it readily to the opposite wall and to the heart–lung interface. This test is commonly used to determine biologic and prosthetic valve dysfunction, to evaluate a pericardial effusion, to evaluate the velocity and direction of blood flow, to furnish direction for further diagnostic study, and to monitor cardiac patients over an extended period. Echocardiography is also used to monitor patients with heart failure relying on a left ventricular assist device. One of the advantages of this study is that it can be performed at the bedside with mobile equipment, if necessary.

The various modes of echocardiography are capable of providing a great range of information concerning cardiac structure and function. The following are common types of echocardiograms:

• 2D: Used to produce grayscale, cross-sectional images of the heart’s anatomy

• M-mode: Used to generate depictions of rapidly moving structures such as valves and for standardized dimensional measurements

• Continuous-wave Doppler and pulsed-wave Doppler: Used to determine velocity of blood flow

• Color 2D: Used for identifying areas of disturbed or eccentric blood flow

• Color M-mode: Used for evaluating movement of cardiac structures

Specialized types of echocardiography include:

• Stress echocardiogram: Used to provide information relating to the function of heart structures during high cardiac output states. A treadmill or upright bicycle may be used, or the heart can be stressed by an infusion of medication.

• TEE: Used to provide a closer view of cardiac structures without interference from superficial chest tissues. A small ultrasound transducer is placed at the end of a tube inserted into the esophagus to obtain images.

• Fetal echocardiogram: Used to identify congenital cardiac defects. It is performed as an abdominal ultrasound or transvaginally.

• Contrast echocardiogram: Used to opacify cardiac structures, this method of echocardiography utilizes contrast material containing nontoxic microbubbles that is injected into a vein.

These special techniques may require a signed, witnessed consent form before performance and involve more complicated procedures. Check with the individual laboratory for specific guides and protocols.

Procedures

1. Ensure that a specific diagnosis accompanies the request for the test (e.g., “rule out pericardial effusion,” “determine severity of mitral stenosis”). If a stress echocardiogram is ordered, the patient’s ability to perform exercise must be indicated.

2. Ask the patient to lie on the examining table in a slight side-lying position.

3. Apply a couplant (ultrasound gel) to the skin surface over the chest to permit maximum penetration of the ultrasound beam. Hold the transducer over various regions of the chest and upper abdomen to obtain the appropriate views of the heart.

4. Tell the patient that there should be no pain or discomfort involved. Leads may be attached for a simultaneous ECG reading during the ultrasound procedure.

5. Tell the patient that the examination time is 30–45 minutes.

6. See Chapter 1 guidelines for intratest care.

Abnormal results help to diagnose:

1. Acquired cardiac disease:

   1. Valvular disease, stenosis, insufficiency, prolapse, and regurgitation

   2. Cardiomyopathies

   3. Coronary artery disease

   4. Pericardial disease, including effusion, tamponade, and pericarditis

   5. Endocarditis

   6. Cardiac neoplasm

   7. Intracardiac thrombi

2. Prosthetic valve function

3. Congenital heart disease (CHD)

Pretest Patient Care

1. Explain the purpose, benefits, and procedure of the test.

2. Assure the patient that no pain is involved; however, some discomfort may be felt from lying quietly for a long period.

3. Explain that a liberal coating of coupling agent must be applied to the skin so that there is no air between the skin and the transducer and to permit easy movement of the transducer over the skin. A sensation of warmth or wetness may be felt.

4. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

1. Dysrhythmias interfere with the test.

2. Hyperinflation of the lungs with mechanical ventilation, especially with positive end-expiratory pressure >10 cm H₂O, precludes adequate ultrasound imaging of the heart.

3. False-negative and false-positive diagnoses have been identified (especially in M-mode echocardiograms), including diagnoses of pleural effusion, dilated descending aorta, pericardial fat pad, tumors encasing the heart, clotted blood, and loculated effusions.

4. Doppler study results can vary greatly if the transducer position does not provide satisfactory angles for the beam.

Normal

• Normal position, size, and movement of heart valves and chamber walls as visualized in 2D, M-mode, and Doppler mode

• Color M-mode and color Doppler assessments of heart structures within normal limits