technetium-tc-99m-exametazime and Syncope

We report here a rare case of repeated syncopal episodes associated with smoking and findings of 99mTc-hexamethylpropyleneamine oxime (HMPAO) brain single-photon emission CT (SPECT) imaging.. A 77-year-old man had four syncopal episodes during a half-month period. All four occurred when he stood up and walked immediately after smoking a cigarette, and syncope did not occur after cessation of smoking. Although upright testing revealed orthostatic hypotension, the patient did not complain of fainting on standing alone. Compared with brain SPECT in the supine position, perfusion was decreased in the posterior circulation structures after the subject smoked a cigarette or chewed nicotine gum.. The combination of cerebral vasoconstriction due to smoking and orthostatic hypotension probably decreased cerebral blood flow in this patient, resulting in syncope.

Topics: Aged; Cerebrovascular Circulation; Humans; Male; Organotechnetium Compounds; Oximes; Smoking; Syncope; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

A case of Takayasu's disease in a 22-year-old woman who complained of severe fainting attacks is presented. Bilateral obstruction of the cervical arteries was confirmed by digital subtraction angiography. Preoperative technetium-99m hexamethylpropylene amine oxime brain SPET in the sitting position showed bilateral hypoactivity in the temporoparietal areas. Subtraction brain SPET showed slightly increased activity in the lying position. The patient has had no fainting attacks since bypass surgery. Postoperative 99mTc-HMPAO brain SPET in the sitting position showed normal activity except in the right temporoparietal area. This area was filled in the lying position. 99mTc-HMPAO brain SPET is the only technique that can visualize the cerebral blood flow in any position, this capability deriving on the fact that the distribution of 99mTc-HMPAO in the brain is fixed in the first 2-3 min following injection. The use of both sitting and lying 99mTc-HMPAO brain SPET is very useful for detecting an abnormality (i.e. an inhomogeneous response due to the fall in perfusion pressure) that could not be seen if the cerebral blood flow were to be assessed only in the lying position.

Topics: Adult; Brain; Cerebrovascular Circulation; Female; Humans; Organotechnetium Compounds; Oximes; Posture; Syncope; Takayasu Arteritis; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon