Post-stress Myocardial Stunning

Department of Nuclear Medicine

Seoul Nat’l Univ. College of Medicine

Jin Chul Paeng, MD

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

Protocol

STRESS

Tc-99m-MIBI

Dipyridamole Stress0.56 mg/kg/4min

Gated SPECT

1st 2nd

Rest

Tc-99m-MIBI

Gated SPECT Next day

Surface Motion

Stress

Wall

Thickening

Rest

Wall

Thickening

Stress

Rest

Myocardial Stunning

• Classic Concept– Myocardial dysfunction due to temporary d

ecreased perfusion

– Dependent on perfusion reserve

• New Concept – Canty JM et al. JNC 2000;7:509-527

– Two kinds: acute / chronic (repetitive)

– Preliminary state to ‘hibernation’

– A different phase on a continuum of coronary artery disease

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

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 2000;41:27-35

– One-hour poststress myocardial motion shows stunning effect, compared to wall motion at 24-hour after stress

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.