A: The techniques of echocardiography rely on ultrasound reflection off of cardiac structures which are used to generate images of the heart and great vessels.
A: Echocardiograms are typically ordered to investigate for the presence of thrombi, valvular vegetations, anatomic abnormalities, and to evaluate the function of the heart itself.
A: An echocardiogram is warranted in any patient given a new clinical diagnosis of CHF. Echocardiograms are also warranted when there is a sudden worsening in the patient's condition, with the development of a new murmur or arrhythmia, and for the evaluation of therapy, either medical or surgical.
A: The echocardiogram provides an estimation of left ventricular size and motion, ejection fraction, and information on valvular structure and function. Echocardiograms may therefore also suggest the underlying cause of the CHF, i.e., valvular insufficiency, dilated cardiomyopathy.
A: Yes, there is Doppler analysis, M-mode echocardiography, two-dimensional trans thoracic echocardiography (TTE), trans esophageal echocardiography (TEE), and 3-D echocardiography.
A: The TTE provides good images of the heart, the pericardium, and the great vessels. The procedure is by itself without risk and is associated with little discomfort. When stressing the heart with exercise or dobutamine, there is a small risk of arrhythmia, hypotension, and ischemia.
The study depends on good thoracic “windows” from the body surface to the interior of the heart. If a patient has significant lung disease or history of thoracic surgery, images can be compromised. Patients that cannot be laterally rotated such as ICU, ventilator dependent, or post-surgical patients provide additional challenges to the technician. Overweight patients also provide for technically challenged studies.
A: As high as 80 and 100%, respectively
A: The TEE, although more invasive than TTE, circumvents problems created by poor anatomical windows and patient position. It is usually indicated when the physician cannot reliably obtain a TTE. The transducer is fixed to a flexible endoscope and then slid into the esophagus and stomach.
The procedure is uncomfortable to the patient, carries a small risk of oral, pharyngeal, and esophageal trauma. There are also case reports of infective endocarditis associated with TEE.
A: Doppler echocardiography is aimed at acquiring flow rates and for identifying the presence of obstruction, i.e., thrombus, to that flow. Doppler analysis in CHF patients is usually in conjunction with TTE, as flow velocity in the great vessels and across the valves can be assessed along with the function of the heart. Pressure gradients across the valves are also extrapolated from this information using a modified Bernoulli equation. Pressure change = 4 (velocity) 2
A: M-mode echocardiography is one dimensional echocardiography and can generate quantitative estimates of chamber size and function. Two-dimensional echocardiograms rely more on the qualitative descriptions of observers. M-mode echocardiography is dependent upon the patient having symmetrically contracting ventricles.
Note: 3-D echocardiography is growing in accessibility and utility and will likely play a greater role in the evaluation of cardiac function in the next 5-10 years. It promises exceptional images of the heart.
A: This usually entails the use of 2-D and Doppler echocardiography to confirm the suspicion of coronary artery disease, and if present, to determine its severity. Studies are performed at rest and after physical or pharmacological stress. These images are then compared side by side.
A: A positive stress test usually entails evidence of ischemia. Ischemic myocardium performs differently than well-perfused myocardium. One might see regional wall abnormalities, an increase in end systolic volume, and a decrease in ejection fraction with an ischemic heart.
A: 78% and 88%, respectively.