Transient Left Ventricular Dilatation

Transient ischemic dilation (TID) refers to an apparent increase in the size of the left ventricular cavity on stress myocardial perfusion imaging compared to rest imaging (Stolzenberg, 1980).

TID can be seen in the absence of actual left ventricular dilation. Diffuse subendocardial ischemia causes a reduction in radioisotope uptake in a subendocardial distribution, resulting in apparent enlargement of the left ventricular cavity.

Transient dilatation of the left ventricle is most commonly associated with extensive coronary artery disease (Weiss et al, 1987), but may also be seen in hypertension with myocardial hypertrophy (Robinson et al, 1997; Robinson et al, 2000; Emmett et al, 2005), dilated cardiomypathy (Robinson et al, 2000), and hypertrophic cardiomyopathy (Sugihara et al, 1990).

This patient presented with resting chest pain. He has a history of bilateral renal artery stenosis (top image) and hypertension. Myocardial perfusion imaging showed no significant perfusion defect, but there was increased size of the left ventricular cavity on stress images (Str) compared to resting images (Rst). We felt this was likely due to hypertension with myocardial hypertrophy and less likely representative of balanced ischemia in the setting of diffuse coronary artery disease. Three sets of the patient's cardiac enzymes were within normal limits.

References

• Emmett L et al. The role of left ventricular hypertrophy and diabetes in the presence of transient ischemic dilation of the left ventricle on myocardial perfusion SPECT images. J Nucl Med 2005; 46:1596–1601.
• Robinson VJB, et al. Transient ischemic dilatation occurs in patients without severe multivessel epicardial stenoses (abstr). J Investig Med 1997;45:226A
• Robinson VJB, et al. Causes of Transient Dilatation of the Left Ventricle During Myocardial Perfusion Imaging. AJR 2000; 174:1349-1352.
• Stolzenberg J. Dilation of the left ventricular cavity on stress thallium scan as an indicator of ischemic disease. Clin Nucl Med 1980;5:289 -291
• Sugihara H et al. Assessment of transient dilation of the left ventricular cavity in patients with hypertrophic cardiomyopathy by exercise thallium-201 scintigraphy. J Nucl Med 1990; 27:1281–1289.
• Weiss TA, Berman DS, Lew AS, et al. Transient ischemic dilation of the left ventricle on stress thallium-201 scintigraphy: a marker of severe and extensive coronary artery disease. J Am Coll Cardiol 1987;9:752 -759