Stress echocardiography usually done to detect viable myocardium in patients with left ventricular dysfunction who had myocardial infarction. So it helps in deciding the revascularization process.
2. INTRODUCTION
• Based on the fundamental causal relationship between induced
myocardial ischemia and left ventricular regional wall motion
abnormalities
• In the absence of flow limiting coronary stenosis, physiological stress
results in an increase in heart rate and contractility that is maintained
via an increase in myocardial blood flow
• Systolic wall thickening, endocardial excursion, and global contractility
all increase, leading to decrease in end-systolic volume (and an
increase in the ejection fraction) compared with baseline
• Although this response may be blunted in the setting of advanced age
and/or hypertension or in the presence of beta-blocker therapy,
absence of the hypercontractile state in response to stress should
generally be considered an abnormal response
3. INTRODUCTION
• In the presence of a coronary stenosis, the increase in myocardial
oxygen demand that occurs in response to stress is not matched by
an appropriate increase in supply
• If the supply-demand mismatch persists, a complex sequence of
events known as the ischemic cascade will develop
• Soon after the development of a regional perfusion defect, a wall
motion abnormality will occur, characterised echocardiographically as
a reduction in systolic thickening and endocardial excursion
5. INTRODUCTION
• The severity of wall motion abnormality depends on several factors,
including the magnitude of the blood flow change, the spatial extent
of the defect, the presence of collateral blood flow, left ventricular
pressure and wall stress, and the duration of ischemia
• Deterioration in regional wall motion, however, is a specific and
predictable marker of regional ischemia that generally precedes such
traditional manifestations as angina or electrocardiographic
abnormalities
8. TREADMILL EXERCISE
• Common form of stress testing
• Provides useful clinical information that has both diagnostic and
prognostic value, including, exercise capacity, blood pressure
response, and arrhythmias
• Safe and well tolerated
• Can be applied to a large percentage of patients referred for stress
testing
9. TREADMILL EXERCISE
• Imaging is performed before and immediately after treadmill exercise,
without affecting the exercise portion of the test
• Preserves the additional information already available from treadmill
exercise
• Primary disadvantage- difficulty in obtaining images while patients
walk in an upright position
• Imaging is performed in the immediate post-exercise period
10. TREADMILL EXERCISE
• Because ischemia may resolve quickly after termination of exercise, it
is important to complete post exercise imaging as soon as possible,
certainly within 1 to 1.5 minutes after exercise
• The parasternal long- and short-axis and the apical four- and two-
chamber views are used traditionally in the exercise
echocardiography protocols
14. TREADMILL EXERCISE
• Resolution of induced wall motion abnormalities before post exercise
imaging can be completed is a cause of false negative results
• As the heart rate decreases post exercise, wall motion recovers
• If an adequate workload is achieved and post exercise images are acquired
within 1 minute, the likelihood of a false negative finding is minimised
• Exercise duration, extent of disease, workload achieved, or medical therapy
is not predictive of rapid recovery
• However, wall motion abnormalities that persist into late recovery
generally indicate more severe epicardial coronary disease and/or
multivessel disease
15. BICYCLE ERGOMETRY
• First form of exercise used in conjunction with echocardiography
• To perform graded exercise, patients pedal at a constant cadence at
increasing levels of resistance
• Primary advantage is the ability to image throughout exercise,
particularly at peak stress
• Avoids the potential problem of rapid recovery and permits the onset
of a wall motion abnormality to be documented
• Exercise-induced wall motion abnormalities are more frequent, more
extensive, and more easily visualised at peak compared with post-
exercise
16. BICYCLE ERGOMETRY
• Imaging at intermediate stages can also be analysed and this may
improve the sensitivity of the test by facilitating the detection of a
biphasic response
• Application of contrast to stress echocardiography is also easier using
bicycle exercise compared with treadmill exercise
• Major disadvantage is the problem of workload
• Some patients find bicycling in the supine position very difficult which
may prevent an adequate level of stress to be achieved
18. DOBUTAMINE STRESS ECHOCARDIOGRAPHY
• Cardiovascular effects of dobutamine are dose dependent, with
augmented contractility occurring at lower doses followed by a
progressive chronotropic response at increasing doses resulting in
increase in myocardial oxygen demand
• If coronary reserve is limited, myocardial oxygen demand will
eventually exceed supply and ischemia will develop
• Heart rate response is less important with dobutamine compared
with exercise, and ischemia can often be induced even if target heart
rate is not achieved
• The lower heart rate achieved during dobutamine infusion is offset by
the greater augmentation in contractility
19. DOBUTAMINE STRESS ECHOCARDIOGRAPHY
• The primary application of dobutamine echocardiography is in
patients unable to exercise adequately
• As with exercise, the goal is to produce a graded increase in cardiac
workload that can be monitored for the development of ischemia
• Dobutamine is infused at increasing rates for 3- to 5- minute stages
• Atropine can be used to augment the heart rate response
• The use of atropine has been shown to improve sensitivity, especially
in patients taking beta blockers
20. DOBUTAMINE STRESS ECHOCARDIOGRAPHY
END POINTS AND REASONS TO TERMINATE THE DOBUTAMINE
INFUSION DURING STRESS TESTING
• Exceeding target heart rate of 85% age predicted maximum
• Development of significant angina
• Recognition of a new wall motion abnormality
• Decrease in SBP> 20 mmHg from baseline
• Arrhythmia such as AF or nonsustained ventricular tachycardia
• Limiting side effects or symptoms
21. DOBUTAMINE STRESS ECHOCARDIOGRAPHY
• A decrease in blood pressure is an indication of extensive ischemia,
however hypotension may instead indicate the development of LVOT
gradient, which can be recognised using Doppler imaging
• ECG evidence of ischemia is less reliable during dobutamine infusion
than it is during exercise testing
• Thus, neither ST-segment depression nor elevation occurring in the
absence of a wall motion abnormality or typical symptoms is
sufficient reason for terminating the dobutamine infusion
22. DOBUTAMINE STRESS ECHOCARDIOGRAPHY
• Because of the short half life of dobutamine, inducible ischemia can
be readily reversed through termination of the infusion
• In severe cases or when the ischemic manifestations persist, a short
acting intravenous beta blocker (metoprolol or esmolol) is effective
• Common side effects are minor arrhythmias such as premature
ventricular contractions and atrial arrhythmias and minor symptoms
such as palpitations or anxiety
• NSVT occurs in 3% of patients and generally terminates
spontaneously or can be successfully treated with an intravenous
beta blocker
23. DIPYRIDAMOLE AND ADENOSINE
• Potent vasodilators
• Used in conjunction with echocardiography for detection of CAD
• Unlike dobutamine, these agents work by creating maldistribution of
blood flow, that is, by preventing the normal increase in blood flow in
areas supplied by stenotic coronary arteries
• In more extreme cases, flow may actually be diverted away from
abnormal regions (coronary steal), resulting in true ischemia
24. DIPYRIDAMOLE AND ADENOSINE
• Adenosine is a potent and short acting direct coronary vasodilator
• Dipyridamole is slower acting and its effects result from inhibition of
adenosine uptake
• With both agents, the development of a wall motion abnormality is
predicated on the ability to create sufficient maldistribution of
regional blood flow to result in an ischemia-induced wall motion
abnormality
• Compared to dobutamine, these changes tend to be more subtle and
short-lived
25. DIPYRIDAMOLE AND ADENOSINE
• Redistribution of regional blood flow can occur without an associated
wall motion abnormality
• Vasodilator stress agents may be better suited to imaging techniques
that rely on relative changes in perfusion rather than the
development of a wall motion abnormality
• Commonly used with nuclear imaging techniques
26. 3-D STRESS ECHIOCARDIOGRAPHY
• A full volume data set can be acquired and then sliced and displayed
in variety of views
• Multislice imaging- a series of parallel short-axis scans can be derived
and analysed
• Multiplane imaging- traditional orthogonal planes can be derived
from the volumetric data set
• With treadmill exercise, the acquisition of the entire left ventricle in a
single volume shortens post exercise imaging time
27. 3-D STRESS ECHIOCARDIOGRAPHY
• More complete examination of the left ventricle
• Precise alignment and matching of rest and stress views which
facilitates detection of subtle abnormalities
• More accurate means of measuring LV volume and ejection fraction
• Major limitation is suboptimal image quality
28. CHOSING AMONG THE DIFFERENT STRESS
MODALITIES
• For most patient exercise is the preferred form of stress, provided the
patient is capable of adequately performing either treadmill or bicycle
exercise
• Exercise is generally a more sensitive test for the detection of
coronary disease compared with dobutamine
• However when myocardial viability is an issue, pharmacologic stress
testing is preferred
• Dobutamine stress echocardiography is generally limited to patients
who are unable to exercise adequately or to specifically address the
question of viability
29. INTERPRETATION
• Subjective assessment of regional wall motion, comparing wall
thickening and endocardial excursion at baseline and during stress
• The rest or baseline echocardiogram is first examined for the
presence of global systolic dysfunction or regional wall motion
abnormalities
• Subtle abnormalities at baseline, such as hypokinesis of the inferior
wall, may occur in the absence of CAD and represent a cause of false-
positive results
• Interventricular septal motion may be specifically altered in the
presence of LBBB, the post operative state, ventricular pacing, or
pressure or volume overload of the right ventricle
31. INTERPRETATION
• Regardless of the form of stress, the normal response is the development
of hyperdynamic wall motion
• Lack of hyperkinesis is abnormal and is most often caused by the
development of regional myocardial ischemia
• Other factors- nonischemic cardiomyopathy, treatment with beta blocker
agents, certain valve diseases, LBBB, and severe hypertension
• Submaximal exercise resulting in attainment of a low workload is often
associated with the absence of a hyperkinetic response
• If postexercise imaging is performed after treadmill exercise, an excessive
delay in image acquisition may miss the transient hyperkinesis and lead to
a misinterpretation
32. INTERPRETATION
• Limitation of this approach is the subjective and nonquantitative
nature of wall motion analysis
• A practical quantitative approach to interpretation involves the
estimation of LV volume changes during stress
• The normal response to stress includes a decrease in both end-
systolic and end-diastolic volume that can be visually appreciated
using side-by-side inspection of images
• Failure of LV size to decrease is an abnormal response
• An increase in volume with stress often indicates severe and
extensive (multivessel) disease
35. INTERPRETATION
• Supine bicycle exercise is an exception to this rule. With this form of
stress, elevation of the legs increases venous return throughout
exercise so that left ventricular dilation at peak exercise may be a
normal finding
• When image quality is suboptimal, wall motion analysis can be
augmented through the use of contrast agents that improve
endocardial border definition and increase the accuracy of diagnosis
• In general, when two or more LV segments are not seen on the
resting study, use of contrast should be considered
37. INTERPRETATION
• Segmental model for interpreting and reporting stress
echocardiographic results- dividing the left ventricle into 16 segments
• Wall motion grading-
• 1- normal
• 2- hypokinesis
• 3- akinesis
• 4- dyskinesis
• Wall motion is analysed at baseline and a wall motion score index is
generated
38. INTERPRETATION
• Wall motion score index=
• A 17-segment model, which includes an apical cap has the advantage
of being more compatible with most nuclear imaging schemes
• Any score greater than 1.0 indicates the presence of an abnormality
40. CATEGORIZATION OF WALL MOTION
• Hypokinesis is the mildest form of abnormal wall motion, defined as
preservation of some degree of thickening and inward motion of the
endocardium during systole but less than normal (< 5mm of endocardial
excursion)
• Hypokinesis is most likely to be truly abnormal if it is limited to a region or
territory that corresponds to the distribution of one coronary artery and is
associated with normal (or hyperdynamic) wall motion elsewhere
• Tardokinesis- delayed inward motion or thickening
• Analysing wall motion frame by frame or trimming a cine loop to include
only the first half of systole will help identify tardokinesis and distinguish it
from other wall motion responses
41. CATEGORIZATION OF WALL MOTION
• Akinesis is defined as the absence of systolic myocardial thickening and
endocardial excursion
• Translational motion of the heart during systole can create the illusion of
akinesis
• Wall thickening is less translation dependent and should be relied on in
such cases
• Dyskinesis is the most extreme form of a wall motion abnormality and is
defined as systolic thinning and outward motion or bulging of the
myocardium during systole
• A left ventricular segment that is thin and/or highly echogenic indicates
the presence of scar
43. WALL MOTION RESPONSE TO STRESS
• Segments that are akinetic or dyskinetic at baseline, even if wall
motion worsens during stress, are interpreted as indicating infarction,
and the ability to detect additional ischemia in such segments is
limited
• Lack of hyperkinesis-
• Low workload
• Delayed postexercise imaging
• Beta-blockade
• Cardiomyopathy
• Elderly patients especially women may be unable to manifest a
frankly hyperkinetic reaponse
44. WALL MOTION RESPONSE TO STRESS
• A marked increase in blood pressure during exercise can also prevent
the development of hyperkinesis or even result in global hypokinesis
• Segments abnormal at baseline that improve with stress are
uncommon and likely indicate either a normal response or a localised
abnormality in which the improvement is due to tethering from the
surrounding normal myocardium
• With dobutamine, however, improvement may indicate viability and
the potential for recovery after revascularisation
45. STRAIN IMAGING
• More quantitative approach
• Strain is affected early in the course of ischemia and could be a more
sensitive marker of disease
• Potential to identify and quantify subtle manifestations of ischemia
• Relative independence of translational motion and tethering
• Ability to distinguish active from passive motion
• Potential to examine wall motion throughout the cardiac cycle
• Ability to obtain reproducible strain data at higher heart rates is
difficult
47. LOCALISATION OF LESIONS
• Stress echocardiography is more sensitive in patients with multivessel
disease compared with single vessel disease and more accurate for
identifying disease in the LAD or RCA compared with the LCx artery
• Because of the variability in coronary artery distribution, accurate
differentiation between lesions of the RCA and LCx is not always
possible
49. CORRELATION WITH SYMPTOMS AND ECG
CHANGES
• Wall motion has been shown to be more sensitive and specific
indicator than either symptoms or ECG changes for the detection of
CAD
• In most instances, there is concordance among the various
parameters that define ischemia
• One of the most common indications for stress echocardiography is to
assess symptoms in patients who have an abnormal or non-diagnostic
ECG
• Women, because of the higher rate of a false positive stress ECG, are
often considered candidates for stress echocardiography
50. CORRELATION WITH SYMPTOMS AND ECG
CHANGES
• Wall motion changes in the absence of symptoms are usually an
indication of painless ischemia
• Ischemia in the absence of chest pain and/or ST depression is less
extensive and/or severe
• Ischemic ECG changes in the absence of wall motion abnormalities
occurring in patients with a high likelihood of false positive stress ECG
(e.g., women), a normal stress echocardiogram is strong evidence
against coronary disease
• In subsets of patients in whom the ECG is expected to be more
reliable or when the changes are accompanied by typical symptoms, a
false negative echocardiographic result is possible
51. ACCURACY FOR THE DETECTION OF CAD
• Patients with increases wall thickness, in the setting of normal left
ventricular mass have a disproportionately high frequency of false-
negative results
• Patients with concentric remodelling, especially those with
hyperdynamic wall motion and/or a reduced blood pressure response
during dobutamine infusion, may not manifest wall motion
abnormalities in the presence of angiographic CAD
• A normal wall motion response during stress echocardiography, even
in the presence of known CAD, confers a favourable prognosis in most
cases
• LBBB is a common cause of false-positive results
52. MYOCARDIAL PERFUSION IMAGING
• In addition to improving endocardial border detection, contrast
agents can be used to detect changes in myocardial perfusion that
occur in response to stress
• A perfusion defect may precede the development of wall motion
abnormality, so a method to assess myocardial perfusion should
increase the sensitivity of the test to detect ischemia
• For a given stenosis, the spatial extent of the perfusion defect may
exceed that of a wall motion abnormality, especially in the setting of
single-vessel disease
53. MYOCARDIAL PERFUSION IMAGING
• After i/v injection, the distribution of the contrast agent parallels
blood flow and can be visualised as it traverses the microvasculature
of the tissue, generating a time-intensity curve
• Perfusion can be assessed as a relative change (rest vs. stress), a
regional difference (lateral wall vs. septum), or more quantitatively
based on changes in the rate of blood flow or blood volume
• The perfusion information serves as a supplement to wall motion for
the diagnosis of CAD
56. MYOCARDIAL VIABILITY
• Viable myocardium will augment in response to beta-adrenergic
stimulation, whereas nonviable myocardium will not
• Dobutamine is infused at incremental rates while wall motion and
endocardial thickening are carefully monitored
• Biphasic response, augmentation at low dose followed by
deterioration at high dose, is most predictive of the capacity for
functional recovery after revascularisation
• Sustained improvement and no change are patterns that correlate
with nonviability, i.e., lack of improvement after revascularisation
57. NONISCHEMIC HEART DISEASE
INDICATION EXAMPLE
Aortic valve Mild/mod AR with symptoms
Severe AS with no symptoms
Low-flow low-gradient AS
Mitral valve Mild/mod MS with symptoms
Severe MR with no symptoms
Prosthetic valves AVR with suspected patient-prosthesis mismatch
Hypertrophic cardiomyopathy Assessment of MR and/or LVOT gradient
Pulmonary hypertension Exertional symptoms with mild pulmonary HTN at rest
Diastolic dysfunction Dyspnea on exertion, with normal systolic function
Congenital heart disease Aortic coarctation gradient
