Poststress Myocardial Stunning

1
Post-stress Myocardial Stunning

• Department of Nuclear Medicine
• Seoul Natl Univ. College of Medicine
• Jin Chul Paeng, MD

2
Patient

• 6-year-old male
• DOE with cardiac murmur
• FHx of sudden death (Grandfather and father)
• Preexam Dx of Idiopathic Hypertrophic Subaortic
  Stenosis (IHSS)
• Consulted for myocardial SPECT

3
Protocol
STRESS Tc-99m-MIBI
Rest Tc-99m-MIBI
Gated SPECT
Gated SPECT
Next day
1st
2nd
Dipyridamole Stress
0.56 mg/kg/4min
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(No Transcript)
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Surface Motion
6
Stress Wall Thickening
Rest Wall Thickening
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Stress
Rest
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Myocardial Stunning

• Classic Concept
• Myocardial dysfunction due to temporary decreased
  perfusion
• Dependent on perfusion reserve
• New Concept
• Canty JM et al. JNC 20007509-527
• Two kinds acute / chronic (repetitive)
• Preliminary state to hibernation
• A different phase on a continuum of coronary
  artery disease

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Acute Stunning

• Induced by acute stress
• Either physical or psychologic
• Variable duration
• Usually prolonged over from several hours to a
  couple of days
• How about on iatrogenic stress?
• Exercise
• Pharmacoloic
• Inotropics
• Vasodilators

10
Prolonged Stunning

• Transient prolonged stunning induced by
  dipyridamole and shown on 1- and 24-hour
  poststress 99mTc-MIBI gated SPECT
• Lee DS et al.
• JNM 20004127-35
• One-hour poststress myocardial motion shows
  stunning effect, compared to wall motion at
  24-hour after stress

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Summary

• Gated myocardial SPECT in patient with IHSS
  showed decreased motion and thickening at stress
  image while normal motion and thickening at rest.
• It can be stunning effect of dipyridalmole
  stress.