Stress echocardiography

1. Presenter
Dr. Md. Ahasanul Kabir
Resident, Phase B
UCC, BSMMU
Chairperson:
Asso. Prof. Dr. Tanjima Parvin
UCC, BSMMU

2.  Stress echo- combination of echo with physical, pharmacological, or
electrical stress
 Effective method - evaluating for myocardial ischemia (based on
stress-induced regional WMAs
 Used to screen for CAD & identify the coronary territory
 Differentiate viable myocardium from scarred myocardium
 Safe and relatively inexpensive

3.  Assess severity of valvular disease, HCM & exercise-induced pul.
hypertension
 Important prognostic information after MI and prior to noncardiac
surgery

4. • In 1935, Tennant and Wiggers demonstrated - coronary occlusion
results in instantaneous abnormality of wall motion.
• 1979 – Mason et al demonstrated earliest proof of concept by
echocardiographic imaging of this relation
oStudied 13 CAD pts and 11 controls
oM-mode echo & supine bicycle exercise
oStress induced RWMA seen in 19 of 22 segments supplied by stenotic
coronary arteries

5. 1979-80 –Wann et al demonstrated similar findings on early 2D
imaging
1980-90 –
oImprovements in image acquisition techniques – 2D, 3D
oDigital acquisition – Reviewing rest and stress cine loops side by side;
eliminating respiratory interference by ECG gated selection of cardiac cycle

6.  On Physiological stress - No flow limiting stenosis
Demand supply MATCH - increase in
- HR; Global Contractility
- Systolic wall thickening
- Endocardial excursion
- Decrease in End Systolic Volume

7. On Physiological stress - with flow limiting stenosis
oDemand supply MISMATCH -
oIschemic Cascade
oParameters overlap

8. Ischemic cascade

9.  Persistent demand supply MISMATCH
 Reduction in systolic thickening; endocardial excursion
 Regional WMA – Accurate predictor of regional ischemia – usually
occurs prior to ST-T changes, angina
Stress echo

10. Elimination of stress
Rapid normalization of WMA
oDepends on Ischemia severity and duration
oTypically – Complete recovery 1-2 min.
oIf longer – Stunned myocardium – can rarely last for days!

11. Stressor
Exercise Pharmacologic Pacing Combined

12. Exercise stress
Treadmill
Bicycle
Upright
Supine

13. Pharmacologic stress testing
Pharmacologic
stress
Sympathomimetic
Dobutamine
Vasodilator stress
test
Dipyridamole Adenosine
Others
Regadenoson

14. Exercise stress testing
 Preferred over non exercise stress
 More sensitive in ischemia detection
 No single exercise modality have superior
sensitivity
 Treadmill - more widely accepted among
patients & physicians

15.  Up to 30% of patients - not able to achieve adequate level of
exercise stress (cause- PVD, COPD, or musculoskeletal
problems)
 Pharmacologic stress testing is usually indicated in these
patients.

16. Treadmill exercise
 Most common form of stress testing
Imaging – Just before and immediately after treadmill exercise
 Sensitivity is reduced if images are not rapidly obtained (< 90
seconds) after exercise.
 Diagnostic and immensely valuable prognostic information:
Exercise capacity; BP response; arrhythmias

17. Upright bicycle echocardiography
 Baseline images are obtained - in the standard left lateral
position
 Cycle ergometry start with workload of 25 W & ↑ by 25 to
50 W every 2 to 3 mins
 Images obtained & digitized at rest, before peak, at peak, and
after peak exercise

18. Supine bicycle exercise
• Patient is tilted 30° left lateral decubitus position, images obtained &
digitized at rest, before peak, at peak, and after exercise.
• Not widely used.

19. Pharmacologic stress echo

20. Pharmacologic
agents
Dobutamine Dipyridamole Adenosine Regadenoson Enoximone

21. ESC 2009

22. Dobutamine Stress
Preferred
o Conduction disturbances
o Bronchospastic diseases
o On Xanthine medications
o Caffeine containing drinks
Tea/Coffee/Cola
Dipyridamole Stress
Preferred
oHypertension
oAtrial and Ventricular arrhythmias

23. ESC 2009

24. Dobutamine stress echo(DSE)

25. Dobutamine stress echo…
 DSE- most widely used method for assessing viable
myocardium.
 Highly recommended in patients with LV dysfunction who
may benefit from coronary revascularization.

26. Indications of DSE
1. Patients in whom the exercise stress test is contraindicated
2. Patients in whom the exercise stress test is not feasible (e.g. those
with intermittent claudication);
3. Patients in whom the exercise stress test was non-diagnostic or
yielded ambiguous results;
4. Left bundle branch block or significant resting ECG changes that makes
any ECG interpretation during stress difficult;
5. To see myocardial viability

27. 6. Diagnostic evaluation of patients with low-flow/low-gradient AS

28. Protocol
Dobutamine infusion is started at 10 μg/kg/min and increased every 3
minutes to 20, 30, and 40 μg/kg/min.
If the patient has not reached 85% of APMHR by the end of the 40
μg/kg/min dose, a 3-minute dosage of 50 μg/kg/min may be used.
Infusion is begun at lower doses (5 μg/kg/min) if baseline LV function is
abnormal and myocardial viability is being sought.
Images are digitized at rest and at low dosage (5 to 10 μg/ kg/min),
pre–peak dosage (30 μg/kg/min), and peak dosage.

30. Dobutamine SE…
Atropine is used to reach target heart rate > 85% of APMHR if
dobutamine alone is not effective.
Dose: 0.25 to 0.5 mg iv every minute, starting 40 μg/kg/min
dobu dose level and continuing until an end point or total dose
of 2 mg
If 85% APMHR achieved without any other end points,
complete the protocol to the end of the 40 μg/kg/min infusion

31. If angina or severe side effects develop- antidote iv β-blockade (0.5
to 1 mg/kg esmolol over 1 minute or 2 to 5 mg/kg metoprolol
every 2 to 5 minutes)
Esmolol has a very short half-life and may be preferable.

32. Image acquisition
• Traditionally – PLAX, PSAX, A4C, A2C views
• Other views maybe used at discretion of operator
• By convention – 4 quadrant view of above 4 views compiled
• During comparison – Each view side by side – Rest image (left) and
stress image (Right)

34. Low dose

35. Do
• Look at the left ventricle (Not LA)
• Ensure pre & post views are same
• Acquire in inspiration or exhalation
• Optimize positioning
• Sample plenty of cycles
Don’t
• Overgain (Specially in near-field)
• Foreshorten the LV cavity
• Sacrifice speed for perfection

36. Dobutamine side effects
Potential side effect: Arrhythmia provocation
Serious complications: MI, and cardiac arrest
Less serious side effects:
Tremor
Nervousness
Marked hypertensive & hypotensive responses.

37. End points to terminate DSE
Exceeding THR
Development of significant angina or new RWMA
Depending on patients’ clinical status and presence/extent/severity of WMA
Decrease in SBP>20 mmHg from baseline
Depending on patients’ clinical status and LV function/LVOT gradient
Arrhythmias: AF; NSVT
Limiting Side effects and Symptoms

38. ESC 2009

39. Dipyridamole or adenosine
stress echo

40. Dipyridamole or adenosine stress echo
Contraindications:
Hypotension
AV block
H/O severe bronchospasm
Different protocols of dipyridamole infusion

41. Dipyridamole stress echo
Recommended by the ASE is a low-dose two-stage infusion.
- First stage at 0.56 mg/kg over 4 minutes;
- If no A/E or clinical end pointsreached, additional 0.28 mg/ kg infused over 2
minutes.
High-dose of 0.84 mg/kg given over 10 minutes has been developed to
improve the sensitivity of the test relative to low-dose protocols.

42. Adenosine stress echo
Given as a continuous infusion- very short half life.
Protocol: starts at low dose of 80 μg/kg/min & ↑every 3
minutes by 30 μg/kg/min to a peak dose of 170 to 200
μg/kg/min.

43. Regadenoson
 Adenosine receptor agonist with a half life of 2 to 3-minute
 Administered as one 0.4-mg dose over 10 seconds.

44. Antidote
 If hypotension, bradycardia, or bronchospasm occurs, the effects of
dipyridamole, adenosine, and regadenoson can be reversed with IV
aminophylline 25 to 50 mg over 30 to 60 seconds.

45. Image interpretation

47. WMA categorization
Hypokinesis
oMildest WMA
oSome degree of preserved systolic thickening and inward endocardial excursion
– but less than normal
oVarious definitions
- Less than 30% systolic thickening
- Less than 5 mm endocardial excursion
oDistinction from Normal is subtle – Hypokinesis truly abnormal if corresponds to
a coronary territory + normal (or hyperdynamic) motion elsewhere

48. WMA categorization…
 Akinesis
oVarious definitions
- Absence of systolic myocardial thickening and endocardial excursion
- <10% myocardial thickening
oThickening - better measure than endocardial excursion

49.  Dyskinesis
o Most extreme WMA
o Systolic thinning and Systolic outward motion/bulging
 Scar
oThin and/or highly echogenic segment
oUsually akinetic or severely hypokinetic; may be diskinetic

50. ISCHEMIA
HIBERNATION
HIBERNATION
+ ISCHEMIA
SCAR

51. Stress echo responses & interpretation
Resting or
baseline
function
Response to low-
dose
pharmacologic
stress
Peak and post-stress
function
Interpretation
Normal Normal Hyperdynamic Normal myocardium
Normal Normal or new WMA New WMA or lack of
hyperdynamic response; LV
dilation or decreased EF (with
exercise only)
Ischemic
WMA No change No change Infarcted
WMA Improved Decreased (biphasic response) Viable (hibernating)
myocardium
WMA No change Improved Nonspecific

52. WALL MOTION SCORE INDEX
 WMSI = Sum of all segments’ score
No. of segments scored
 WMSI generated at baseline and at peak stress
 On stress, hyperkinesis is given 1 scoring
 Normal WMSI = 1
 Normal study = WMSI of 1 at both baseline and stress
 Abnormal Baseline WMSI (>1), resting Abnormality present

53. False-positive results
1. LBBB, prior cardiac surgery (e.g., myectomy)
2. Right ventricular pacing
3. Nonischemic cardiomyopathy
4. Hypertensive response to exercise (SBP >
220 mm Hg, DBP > 110 mm Hg)
5. Over interpretation
6. Basal inferior or septal WMA
7. Poor image quality
False-negative results
1. Single-vessel disease
2. Inadequate level of stress (more likely with β-
blockers)
3. LV cavity obliteration (more likely to occur
with dobutamine)
4. Left circumflex disease
5. Delay in capturing images after maximal
stress
6. Poor image quality

55. Assessment of viability…..
 Myocardial contractility ceases when ≥20% of the transmural thickness
is ischemic or infarcted.
 DSE detect viable myocardium (stunned or hibernating)
 A contractile response to dobutamine requires that at least 50% of the
myocytes in a given segment are viable.

56.  Demonstration of a biphasic response to low-dose (5 to 10 μg/kg/min)
dobutamine strongly suggests viable myocardium.
 A biphasic response is present when a resting WMA improves in
response to low-dose dobutamine and decreases in function at peak
stress or post-stress.
 Wall thickness is < 6 mm, there is a low likelihood of recovery of
function.

57. Prognostic role of stress echocardiography

58. Suspected or known chronic CAD
 -ve test result portends an extremely low risk of subsequent CV events
(event rate of < 1%/y subsequent 4 to 5 years)
 Pts at intermediate risk for CAD -with abnormal SE findings - 1-year CV
event 10-30%.
 Pts with the same pretest probability- nonviable myocardium during SE
→ higher rates of cardiac events than with normal SE findings

59. Before non cardiac surgery
 Preoperative evaluation studies conducted with pharmacologic stress
agents, primarily dobutamine.
 A low ischemic threshold during stress (ischemia at heart rate < 70%
APMHR) - strongest predictor of perioperative cardiac events.
 Predictive value of positive test ranges from 7% to 25% for hard events
(i.e., MI or death).

60. Stress Echo in nonischemic
cardiac disease

61. • Used to evaluate the functional significance of a variety of
valvular lesions -
o Aortic stenosis
o Mitral regurgitation
o Mitral stenosis
o Hypertrophic cardiomyopathy

62. Aortic stenosis
 Contraindicated in symptomatic AS.
DSE is reasonable in the diagnostic evaluation of patients with low-
flow/low-gradient AS (Doppler-derived AVA < 1 cm2 & mean gradients <
30 mm Hg).
Used to assess both the severity of AS and the presence of contractile
reserve.
Low-dose (20 μg/kg/min) dobutamine infusion results in increased
cardiac output with a parallel rise in the mean transvalvular gradient.

64. Stress echo in other valvular disease
MR: to assess exercise tolerance and the effects of exercise on
pulmonary artery pressure and severity of MR
MS: hemodynamic response of the mean gradient and pulmonary
artery pressure
HCM: exercise hemodynamics and the inducibility of LVOT, worsening
of mitral regurgitation, and provocable gradients in patients that are
asymptomatic at rest

66. TAKE HOME MESSAGES
Effective method - evaluating for myocardial ischemia Used to screen for CAD &
identify the coronary territory
 Differentiate viable myocardium from scarred myocardium
 Safe and relatively inexpensive
Important prognostic information after MI and prior to noncardiac surgery
 Wall motion and perfusion (or CFR) changes are highly accurate, and more accurate
than ECG changes, for detection and location of underlying coronary artery disease.

67. Exercise, dobutamine, and vasodilators are equally potent ischaemic stressors for inducing
wall abnormalities in the presence of a critical epicardial coronary artery stenosis.
Dobutamine stress echocardiography is by far the most widely used method for assessing
viable myocardium.
 Exercise is safer than pharmacological stress.
Both the doctor and the patient should be aware of the rate of complications
Stress echocardiography should be preferred due to its lower cost, wider availability, and—
most importantly— for its radiation-free nature.

68. THANK YOU