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Imaging
Past, Present, and Future of Stress Echocardiography—
How Far Have We Come and How Far Can We Go?
a report by
Nithima Chaowalit, MD
1
and Patricia A Pellikka, MD
2
1. Division of Cardiology, Department of Medicine, Siriraj Hospital, Mahidol University, Bangkok;
2. Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
How Far Have We Come? The advent of offline digital handling for data acquisition, storage, and
Cardiac imaging using ultrasound (so-called ‘echocardiography’) was display, further improvements in echocardiographic imaging techniques,
introduced more than 50 years ago. Resting echocardiographic detection of and the development of a wide variety of stressor modalities contributed to
myocardial infarction was described as the reduction in regional contractile rapid growth in the field of stress echocardiography.
function,
1
and the development of stress echocardiography in the early era
was recognized after the introduction of 2D echocardiographic imaging. The Methodology
initial report in 1979 by Wann et al. demonstrated the value of 2D Images are acquired in multiple views at baseline and at varying stages
echocardiography in identifying exercise-induced wall motion abnormalities.
2
during stress and/or recovery. Representative images are then displayed in a
During the early days of stress echocardiography, problems included imaging side-by-side format for the comparison of either various stages of the same
quality and techniques. For evaluating patients with known or suspected echocardiographic view or individual views at each stage of stress. Regardless
coronary artery disease (CAD), there was also the need to establish equivalent of the stressors, the echocardiographic detection of inducible ischemia as
accuracy and prognostic values to the well-established alternative imaging new or worsening wall motion abnormalities remains the hallmark of the
technique, stress radionuclide myocardial perfusion imaging. The acquisition positive test result for the diagnosis of CAD. The wall motion abnormalities
of stress echocardiographic imaging initially involved continuous videotape can be matched to the standardized multisegment left ventricular (LV) model,
recording for sequential evaluation of wall motion; the development of the as recommended by the American Society of Echocardiography (ASE).
5
digital acquisition system for the side-by-side comparison of rest and post- Additional information, such as a change in LV volume during stress, provides
stress imaging was a major advance. additive value with respect to accuracy and prognosis.
Early studies of stress echocardiography employed exercise as a stressor and Exercise remains the prototype for stress testing in the diagnosis of CAD. It
were mostly feasibility studies.
2–4
Any form of physical exercise that provides an was the first stress modality to be combined with echocardiography and
appropriate increase in heart rate and cardiovascular workload can be used in remains popular in clinical practice. The very first reports of stress
the performance of exercise echocardiography. However, the technique of echocardiography dealt with the use of M-mode echocardiography with
exercise echocardiography is challenging in terms of image acquisition during exercise in normal subjects
6
and in patients with CAD.
7
Subsequently, 2D
physical exercise (either on a treadmill or on a bicycle). Furthermore, the echocardiography was introduced to detect exercise-induced ischemic wall
feasibility of exercise echocardiography is limited in patients who are unable or motion abnormalities.
2
Exercise echocardiography can be performed using a
unwilling to exercise, or when myocardial viability is an important issue. This led treadmill or a bicycle. The most commonly employed form of exercise
to the development of various forms of pharmacological and other non- echocardiography involves immediate imaging after treadmill use. Images are
exercise stressors (see Table 1). acquired at rest as a baseline for comparison and either immediately after
treadmill exercise or during various levels of bicycle exercise. It is possible to
obtain additional Doppler data during bicycle exercise; this test may also be
Nithima Chaowalit, MD, is an Assistant Professor of Medicine
and an echocardiologist in the Division of Cardiology of the
used for assessing valvular heart disease or exertional changes in diastolic
Department of Medicine at Siriraj Hospital, Mahidol University. function. Data regarding hemodynamic response to exercise, exercise
She worked with Dr Pellikka as a Research Fellow in the field
capacity, and arrhythmias have also added useful diagnostic and prognostic
of stress echocardiography at Mayo Clinic, Rochester.
information and should be included in the report. Ischemic threshold and the
heart rate or percentage of target heart rate at which ischemia first occurs
can be obtained from bicycle exercise but not from treadmill exercise.
Patricia A Pellikka, MD, is a Professor of Medicine at Mayo
Clinic College of Medicine. She is also Co-Director of
Pharmacological stress echocardiography is an alternative in patients who are
the Echocardiography Laboratory and Director of the unable to exercise or when assessment of viable myocardium is an issue.
Echocardiography and Vascular Physiology Research Unit at
Among pharmacological stress agents, dobutamine and dipyridamole are
Mayo Clinic. She was responsible for introducing stress
echocardiography into clinical practice at Mayo Clinic.
popular. Dobutamine provides a balanced inotropic and chronotropic
response, and has become the most commonly utilized pharmacological
E:
pellikka.patricia@mayo.edu
stressor. Images are acquired at baseline and during each sequential stage of
dobutamine infusion. The protocol for dobutamine stress echocardiography
28 © TOUCH BRIEFINGS 2008
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