CHAPTER 90 Echocardiography
The prevalence of heart disease will continue to increase in the United States as the population ages. The amount of heart disease managed by primary care clinicians will also continue to increase. In many cases, both the management and the prognosis of heart disease are based on the amount of remaining viable myocardium. This is especially true for patients with congestive heart failure (CHF), cardiomyopathy, arrhythmias, and ischemic heart disease. One method of quantifying the remaining viable myocardium is to assess the ejection fraction. In fact, the most common reason echocardiography is currently performed in the United States is to determine the ejection fraction.
Many common symptoms, signs, or diagnoses of heart disease (e.g., palpitations, cardiomegaly on electrocardiogram [ECG] or chest x-ray, atrial fibrillation, CHF) are evaluated or managed based on data from echocardiography (Table 90-1). In certain situations, the more readily available the echocardiogram, the better the management. For example, acute chest pain is managed differently when echocardiography is immediately available. Even extracardiac causes for acute chest pain, some of which can be life threatening (e.g., pulmonary embolus, aortic dissection), can be diagnosed with echocardiography. If an acute myocardial infarction (MI) is diagnosed, risk stratification can be performed immediately. Complications from an acute MI can also often be diagnosed early.
TABLE 90-1 Common Symptoms and Differential Diagnosis for Echocardiography
Reason for Echocardiography | Differential Diagnosis |
---|---|
Chest pain | |
Heart failure | |
Palpitations | |
Murmur: systolic | |
Murmur: diastolic | |
Cardiomegaly on chest x-ray | |
Systemic embolic event |
Adapted from Otto CM: Textbook of Clinical Echocardiography, 2nd ed. Philadelphia, WB Saunders, 2000.
Other common diagnoses that can be made or evaluated in the primary care clinician’s office with echocardiography include mitral valve prolapse, dilated left atrium (important for patients with atrial fibrillation), left ventricular hypertrophy, transient ischemic attack, and ischemic heart disease. Whether in the clinician’s office, the hospital, or the emergency department, a rapid diagnosis of pericardial tamponade or a pericardial effusion may be life-saving. Furthermore, if pericardiocentesis is needed, the risk of complications is significantly reduced if it is performed under ultrasonic guidance (see Chapter 214, Pericardiocentesis).
Improvements in image quality, portability, and affordability for real-time sonography have allowed it to become a valuable adjunct for the clinician in the office, in the hospital, or in the emergency department. Albeit not by much, the cost of echocardiography equipment has also decreased as the technology has expanded and improved. Consequently, echocardiography has seen some of the most rapid growth among procedures performed by primary care clinicians (see Chapter 94, Stress Echocardiography). For those clinicians with a large number of adult patients, two-dimensional (2D) and M-mode echocardiography may be a welcome addition to their practice. If the primary care clinician is uncomfortable performing echocardiography, contractors are available to provide sonographers. Over-reading services are also available (see the “Suppliers” section). This chapter predominately describes the performance of a 2D/M-mode echocardiogram with a brief summary of common findings. Since color and Doppler flow imaging are helpful for almost all echocardiograms, especially for those assessing the hemodynamic severity of an abnormality, they will also be discussed briefly. For a discussion of ultrasound principles and concepts, and for information regarding limited echocardiography, see Chapter 225, Emergency Department, Hospitalist, and Office Ultrasonography (Clinical Ultrasonography). Electromechanic dissociation, pericardial effusion, pericardial tamponade, and assessing intravascular volume status, right ventricular strain/dysfunction, and acute pulmonary hypertension (e.g., pulmonary embolism) are briefly discussed in that chapter. (Assessing for possible pulmonary hypertension is also discussed in the Interpretation section of this chapter.)
M-mode echocardiography produces graphic images in which time makes up the horizontal axis and the structures in motion being scanned compose the vertical axis. In other words, wherever the cursor is placed on the image, a linear beam of ultrasound is directed through the corresponding tissue and movement of the structures is graphically imaged over time. The resultant M-mode tracing can then be used to look at excursion and contraction patterns as well as to precisely measure distances from the various horizontal structures over time. Chamber dimensions, wall thicknesses, and valve excursions can be measured precisely throughout the cardiac cycle. From chamber dimensions, an ejection fraction can be estimated.
Doppler flow imaging is used to measure the velocity of blood flowing over certain structures. Using the Bernoulli equation, pressure gradients (e.g., across a valve) can also be determined. As with M-mode, time and the cardiac cycle are graphed along the horizontal axis while the vertical axis consists of blood velocity in meters per second. By convention, flow toward the transducer is depicted above the baseline and flow away from the transducer is depicted below the baseline. Pulsed wave (PW) technology and measurements utilize tiny, three-dimensional sample volumes to detect the exact location of any abnormalities. However, PW Doppler is limited when there is high-velocity flow. Continuous wave (CW) technology utilizes two crystals (one continuously emitting sound waves, the other continuously listening for echoes) and can measure high velocities (e.g., stenotic valves). However, it is of limited use for localizing abnormalities. As a result of these limitations, both PW and CW should be utilized with every valve. Color flow Doppler is a special adaptation of PW technology. It uses thousands of sampling volumes to produce a color image of velocities. By convention, flow away from the transducer is blue and flow toward the transducer is red. The intensity of the color increases with the velocity.
Preprocedure Patient Preparation
Indications for the study and possible findings should be explained to the patient. The patient should be prepared to change positions, if possible, while being scanned. The patient should be prepared for adequate gel and pressure from the transducer to be applied to the parasternal, apical, suprasternal, and, possibly, subxiphoid areas of the chest and abdominal walls. The patient should be gowned and in the supine or left lateral decubitus position.
Equipment
Technique
Two-Dimensional Echocardiography
Viewing the front of the chest, if the 12 o’clock position is considered cephalad and the 6 o’clock direction caudal, the axis of the heart is usually located in a line drawn between the 10 o’clock and the 4 o’clock positions. Placing the marker dot of the transducer at about the 10 o’clock position usually produces the long-axis view of the heart, especially if the probe is located parasternally. A line drawn between the patient’s right shoulder and left hip also approximates the long axis of the heart. The long-axis view is essentially the longitudinal view of the heart, if described in the conventional terminology of ultrasound for the remainder of the body. Rotating the marker dot almost 90 degrees or perpendicular to the long axis, to the 2 o’clock position, produces the short-axis view of the heart. This is essentially a transverse view of the heart (Fig. 90-1). A line drawn between the left shoulder and the right hip also approximates this axis.

Figure 90-1 Parasternal short-axis view at the level of the mitral valve (MV). LV, left ventricle; RV, right ventricle.
(From Reynolds T: The Echocardiographer’s Pocket Reference, 2nd ed. Phoenix, School of Cardiac Ultrasound at Arizona Heart Institute, 2000.)
Because the patient is usually lying in the left lateral decubitus position while being scanned and the transducer is placed on the anterior chest wall (or abdominal wall for the subxiphoid view), the transducer edge will be noted at the top of the image. Posterior cardiac structures will be located at the bottom (inferior aspect) of the image. With the usual orientation, if the directional marker is noted on the right side of the image, objects to the right of the screen will correspond to objects near the marker dot on the transducer.

Figure 90-2 Parasternal long-axis view. Ao, aortic root; CS, coronary sinus; DTA, descending thoracic aorta; LA, left atrium; LV, left ventricle; RV, right ventricle.
(From Reynolds T: The Echocardiographer’s Pocket Reference, 2nd ed. Phoenix, School of Cardiac Ultrasound at Arizona Heart Institute, 2000.)

Figure 90-3 Parasternal long-axis view of the right ventricular inflow tract (RVIT view). IVC, inferior vena cava; RA, right atrium; RAA, right atrial appendage; RV, right ventricle, TV, tricuspid valve.
(From Reynolds T: The Echocardiographer’s Pocket Reference, 2nd ed. Phoenix, School of Cardiac Ultrasound at Arizona Heart Institute, 2000.)

Figure 90-4 Parasternal short-axis view at the level of the aortic valve. DTA, descending thoracic aorta; L, left coronary cusp; LA, left atrium; LPA, left pulmonary artery; N, noncoronary cusp; PA, pulmonary artery; PV, pulmonary valve; R, right coronary cusp; RA, right atrium; RPA, right pulmonary artery; RVOT, right ventricular outflow tract; TV, tricuspid valve.
(From Reynolds T: The Echocardiographer’s Pocket Reference, 2nd ed. Phoenix, School of Cardiac Ultrasound at Arizona Heart Institute, 2000.)

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