Transient ischemic dilatation

Case contributed by Matt A. Morgan


Chest pain

Patient Data

Age: 65 years
Gender: Male
Nuclear medicine

Myocardial SPECT Lexiscan (40 mCi of Tc-99m-MIBI).

Full myocardial SPECT Lexiscan study

Nuclear medicine

Full study with all three orthogonal planes. There is a small, fixed apicoseptal perfusion defect as well as transient ischemic dilatation with stress. The green arrows point to representative pairs of stress/rest images (stress on top, rest on bottom), demonstrating an increase in the size of the left ventricle with stress (TID ratio 1.34).

Myocardial SPECT Lexiscan in a different patient

Nuclear medicine

Myocardial SPECT Lexiscan (40 mCi of Tc-99m-MIBI) with gated SPECT analysis on both resting and post-stress images. There is a small, mild anteroapical perfusion defect which is fully reversible. There is also transient ischemic dilatation (ratio 1.28). Note how the left ventricular cavity is larger in stress than in rest.

Myocardial SPECT Lexiscan (40 mCi of Tc-99m-MIBI) with bull's eye view and LV chamber modeling. The red arrows point to stress: rest pairs exhibiting TID.

Case Discussion

Transient ischemic dilatation is a paradoxical phenomenon seen in myocardial SPECT perfusion imaging.  With severe balanced coronary artery disease, myocardial ischemia may result in apparent enlargement of the left ventricular cavity during stress. The cause of this is not entirely clear, but some speculate that it may be (at least partly) due to extensive subendocardial ischemia.

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