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Tests & Services
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Tests & Services |
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Ambulatory Blood Pressure Monitoring Brachial Artery Ultrasound Imaging Dobutamine Stress Echocardiography |
Quantitative Analysis of Echocardiograms |
Abdominal Aortic Ultrasound evaluation is performed with an ultrasound transducer (probe) over a segment of the main artery supplying blood to the organs in the abdomen and legs for "bulging" or "ballooning", which is an abdominal aortic aneurysm. The test can determine if an aneurysm is present, and also can provide measurements of the aorta to determine the precise location and the size of the vessel.
Ambulatory Blood Pressure Monitoring
Ambulatory Blood Pressure Monitoring is employed over a 24-hour period to sample systolic, diastolic and mean arterial pressures at a programmable interval. Data are analyzed for daytime and nighttime variability with a capacity for over 80 individual measurements that can be stored for future off-line analysis.
To calculate the ankle/brachial index (ABI), systolic blood pressure is measured by Doppler ultrasonography in each arm, in the dorsalis pedis (DP) and posterior tibial (PT) arteries in each ankle. The higher of the two arm and ankle pressures is selected. The right and left ABI values are determined by dividing the higher ankle pressure in each leg by the higher arm pressure.
Brachial Artery Ultrasound Imaging
Brachial Artery Ultrasound Imaging is performed to assess endothelial function by evaluating the post-ischemic reactive hyperemia. Measurements of the vessel diameter are performed prior to, during a 5 minute inflation, and immediately after deflation of a pneumatic cuff. Brachial artery blood flow velocity is measured with spectral Doppler. The normal percent increase in diameter of the artery (flow-mediated dialation) and systolic flow after cuff deflation is used as an index of endothelial-dependent vasodilation response. When the percent increase in diameter is blunted or absent, underlying endothelial dysfunction is present, a putative marker of atherogenesis. All studies are repeated with a second hyperemic challenge with sublingual nitroglycerin to determine the endothelium-independent response.
Carotid Ultrasound Imaging examines the carotid arterial system (common, external and internal) for identification of atherosclerotic plaques and measurements of the intima-media thickness of the carotid arterial wall. Spectral Doppler and color flow imaging allow characterization flow disturbances and measurement of velocities to localize and quantify the extent of vessel stenosis using a standardized grading system.
Dobutamine Stress Echocardiography
Dobutamine Stress Echocardiography uses a standardized protocol of intravenous dobutamine to achieve a target heart rate. Twelve-lead electrocardiogram, blood pressure monitoring and echocardiography are performed at baseline and continuously during infusion. This procedure is employed for the assessment of coronary artery disease and myocardial viability in patients with known coronary disease or cardiomyopathy. Patients undergoing exercise stress testing and pharmacologic stress echocardiography are closely supervised by a physician, registered nurse and a cardiac sonographer.
Exercise ECG Stress Testing uses standardized protocols to measure the heart rate and blood pressure response to dynamic exercise. The 12-lead electrocardiogram is analyzed for ST segment alterations and for the presence of arrhythmias, which are suggestive of myocardial ischemia.
Exercise Stress Echocardiography
Exercise Stress Echocardiography is two-dimensional echocardiographic imaging of the left ventricle at rest and immediately post exercise to assess ventricular wall motion, ejection fraction and chamber volumes. Coupling exercise ECG with echocardiographic images improves the sensitivity and specificity for detecting myocardial ischemia compared with ECG stress test alone. Cardiac Doppler can be employed to assess changes in gradients [e.g., aortic stenosis, hypertrophic cardiomyopathies] or the presence of pulmonary hypertension when evidence of tricuspid regurgitation can be detected at rest and post exercise. Other measurements can be incorporated by request of investigators.
Lower extremity venous ultrasound imaging examines the venous system in the legs for the presence of venous thrombosis. The vessels examined include the common femoral, deep superficial femoral, popliteal, posterior tibial and peroneal veins. Measurements can be performed to determine lumen size. Doppler and color flow is done to assess the presence of venous flow.
Maximal O2 Uptake Testing provides an assessment of oxygen uptake (VO2) during exercise and related cardiopulmonary parameters to evaluate functional status.
Typical measures of phenotype, including height, weight, waist and hip circumferences can be recorded.
Full two-dimensional, Doppler, tissue Doppler and color-flow imaging studies can be obtained at other Washington University or Barnes-Jewish Hospital sites to assess cardiovascular function simultaneously with other non-invasive studies.
Quantitative Analysis of Echocardiograms
Previously obtained two-dimensional and Doppler echocardiograms can be quantitatively analyzed for cardiac chambers' dimensions, left ventricular systolic and diastolic function. Our laboratory can be used as a core reading facility for multicenter trials.
Strain Gauge Plethysmography is a standardized technique to measure flow and vascular resistance by using a special transducer placed on the forearm and use of two inflated blood pressure cuffs proximal and distal to the site for the temporary occlusion of either venous or arterial flow. This technique also has been used to assess endothelial dysfunction by measurements of blood flow volume and rate of flow into the forearm.
Transthoracic Echocardiography
Transthoracic Echocardiography uses ultrasound to provide real time visualization of cardiac structures and function. The standard examination consists of M-mode, two-dimensional, pulsed and continuous wave spectral Doppler and color flow imaging. M-mode and 2-dimensional imaging are used to provide qualitative and quantitative data regarding cardiac chamber dimensions, left ventricular systolic performance (fractional shortening and ejection fraction) and determination of left ventricular mass for the evaluation of ventricular hypertrophy. Doppler and color flow imaging provide qualitative and quantitative data to detect valvular regurgitation or stenosis, an estimate of cardiac pressures and output, and an assessment of diastolic filling abnormalities of the ventricles. All measurements are averaged from 3 to 5 cardiac cycles and studies are performed by experienced, nationally credentialed professionals in cardiac ultrasound. Additional or special measurements are available upon request of investigators.
Twelve-Lead Electrocardiography (ECG)
Twelve-lead electrocardiography (ECG), which is a recording of the electrical activity of the heart, is a standard screening tool used to detect evidence of prior myocardial infarction, ischemia or cardiac arrhythmias. This study includes both the acquisition and interpretation.
Copyright © 2000 Cardiovascular Imaging and Clinical Research Core Laboratory.