Takayuki Morishima

Reliability of pressure-derived myocardial fractional flow reserve in assessing coronary artery stenosis in patients with previous myocardial infarction

In 167 patients with suspected coronary artery disease, 74 of whom had myocardial infarction (MI), measurement of myocardial fractional flow reserve (FFR) in previous infarction territories, using a cut-off point of 0.75, showed a sensitivity of 79% and a specificity of 79% for myocardial ischemia as demonstrated by thallium-201 myocardial imaging. This sensitivity and specificity were similar to a sensitivity of 79% and a specificity of 72% observed in territories not related to MI. In addition, a receiver-operating characteristic curve analysis revealed that the best predictability of FFR for myocardial ischemia was between 0.74 and 0.76, regardless of the presence or absence of MI.

Effect of percutaneous coronary angioplasty on myocardial perfusion, function, and wall thickness as assessed by quantitative gated single-photon emission computed tomography

In conclusion, improvement in myocardial ischemia, hibernation, and left ventricular function with coronary revascularization can be assessed in detail by applying gated SPECT. In particular, the beneficial effects were demonstrated, even in non-revascularized territories, through good collateral circulation in which blood flow was improved by revascularization.

Coronary arterial spasm during adenosine myocardial perfusion imaging

Adenosine is widely used as a pharmacologic agent for stress myocardial perfusion imaging. Vasospasm as a side effect of adenosine has been reported a few times in other countries, but it has not been reported in Japan. A 65-year-old woman was admitted to our hospital because of chest pain at rest and during exercise. She underwent myocardial scintigraphy, to rule out myocardial ischemia. After adenosine infusion, she felt chest pain and the electrocardiogram (ECG) showed ST elevation in inferior leads. Adenosine infusion was stopped immediately. Her chest pain resolved, and the ECG reverted to baseline. Perfusion image presented reverse redistribution in inferior segments, and coronary angiography revealed insignificant lesions. Transient ST elevation during adenosine infusion is thought to be due to coronary vasospasm, judging from scintigraphic and angiographic findings.

High-tension electrical injury to the heart as assessed by radionuclide imaging

To evaluate cardiac complications associated with electrical injury, 7 patients with high-tension electrical injury (6,600 V alternating current) underwent201Tl and123I-metaiodobenzylguanidine (MIBG) imaging in addition to conventional electrocardiographic and echocardiographic assessments. Electrocardiography showed transient atrial fibrillation, second degree atrioventricular block, ST-segment depression, and sinus bradycardia in each patient. Echocardiography showed mild hypokinesis of the anterior wall in only 2 patients, but201Tl and123I-MIBG myocardial scintigraphy whowed an abnormal scan image in 6/7 and 5/6 patients, respectively. Decreased radionuclide accumulation was seen primarily in areas extending from the anterior wall to the septum. Decreased radionuclide accumulation was smaller in extent and milder in degree in123I-MIBG than in201Tl imaging. These results suggest that even in patients without definite evidence of severe cardiac complications in conventional examinations, radionuclide imaging detects significant damage due to high-tension electrical injury, in which sympathetic nerve dysfunction might be milder than myocardial cell damage.