Manabu Miyagi

Important parameters in the detection of left main trunk disease using stress myocardial perfusion imaging

OBJECTIVES We sought noninvasively to diagnose left main trunk (LMT) disease using myocardial perfusion imaging (MPI). METHODS Five hundred and eight patients with suspected coronary artery disease (CAD) underwent both stress MPI and coronary angiography. The extent and severity of perfusion abnormalities were assessed using a 20-segment model. In addition, perfusion defects in both left anterior descending and left circumflex arterial territories were defined as a left main (LM) pattern defect, and those in 3-coronary arterial territories as a 3-vessel pattern defect. RESULTS In 42 patients with LMT disease, a summed stress score (19.4 ± 10.0 vs. 13.5 ± 10.0; p < 0.0001) and a summed rest score (12.1 ± 9.7 vs. 7.0 ± 7.8; p = 0.002) were greater than in 466 patients without LMT disease, while a summed difference score was similar (7.3 ± 7.7 vs. 6.5 ± 6.1; p = NS). The prevalence of an LM-pattern defect was low in both groups (12% vs. 8%; p = NS). However, a 3-vessel pattern defect (33% vs. 7%; p < 0.0001), lung uptake of radiotracers (38% vs. 11%; p < 0.0001), and transient ischemic dilation (31% vs. 13%; p = 0.003) were more frequently observed in patients with LMT disease than in those without. Logistic regression analysis showed that a 3-vessel pattern defect (OR=3.5, 95% CI = 1.4-8.8; p = 0.007), lung uptake of radiotracers (OR = 2.5, 95% CI = 1.1-5.7; p = 0.03), and previous myocardial infarction (MI) (OR = 2.4, 95% CI = 1.0-5.7; p = 0.05) were the most important parameters to detect LMT disease. After excluding 163 patients with previous MI, a repeat analysis revealed that lung uptake of radiotracers (OR = 8.2, 95% CI = 2.3-29.2; p = 0.001) and an LM-pattern defect (OR = 6.3, 95% CI = 1.4-27.2; p < 0.02) were independent predictors for LMT disease. CONCLUSION In the identification of LMT disease, lung uptake of radiotracers was a single best parameter, which was independent of the presence or absence of previous MI.

In vivo intravascular laser photodynamic therapy in rabbit atherosclerotic lesions using a lateral direction fiber

This study was performed to evaluate the possibility of inducing regression of atherosclerotic foci by photodynamic therapy (PDT) using hematoporphyrin derivative (HpD).

Differential effects comparing exercise and pharmacologic stress on left ventricular function using gated Tc-99m sestamibi SPECT

ObjectiveAlthough post-ischemic stunning has emerged as an important marker for severe coronary artery disease (CAD), differences in stress methods may have different effects on left ventricular (LV) volumes and function.MethodsTo assess differential effects comparing exercise and pharmacologic stress on the LV measurements, 99mTc-sestamibi gated single-photon emission computed tomography (SPECT) acquired more than 30 min after stress and at rest was evaluated in 38 patients undergoing adenosine triphosphate (ATP) stress (ATP group) and 38 age-and sex-matched patients subjected to exercise stress (Ex group) among 268 patients with normal SPECT findings.ResultsCoronary risk factors and LV volumetric measurements at baseline were similar in the two groups. Compared with volumetric measurements at rest, enddiastolic volume (EDV) increased (72 ± 21 ml to 74 ± 21 ml; P = 0.01), end-systolic volume increased (25 ± 12 ml to 28 ± 13 ml; P = 0.001), and ejection fraction (EF) decreased after stress (66% ± 8% to 63% ± 9%; P < 0.002) in the ATP group. In the Ex group, by contrast, no such change was observed. In addition, changes in EDV (3 ± 6 vs. −1 ± 5 ml; P = 0.01) and the stress-to-rest ratio of EDV (1.04 ± 0.09 vs. 0.99 ± 0.08; P < 0.02) after stress were greater in the ATP than in the Ex group.ConclusionsDifferential effects of stress methods on LV volumes persist more than 30 min after the stress. These findings should be kept in mind when interpreting post-ischemic stunning.

Photodynamic therapy for the prevention of restenosis after angioplasty

The purpose of this study was to evaluate whether photodynamic therapy (PDT) can destroy the proliferating smooth muscle cells and therefore suppress the occurrence of restenosis after angioplasty. PDT following administration of hematoporphyrin derivatives (HpD) 24 hours before irradiation was performed on 30 rabbits immediately (0D), 3 days (3D), 1 week (1W) and 2 weeks (2W) after balloon injury. HpD accumulation of each group was investigated simultaneously. Irradiation of 27 J/10 mm2 from an Hg-Xe flash lamp light transmitted through an 800 micrometers quartz fiber with a diffusing tip was used. All rabbits were sacrificed 4 weeks after balloon injury. The results were expressed in terms of intima:media thickness ratio at the site of fiber contact (I/M) and intima:media area ratio of the cross section (IA/MA). Inhibition of intimal thickening evaluated on the basis of the I/M ratio was recognized in the 3D-, 1W-, and 2W-PDT group. The most effective photoradiation was at the 1W-PDT (I/M equals 0.78 +/- 0.67), but in 2W-PDT intimal necrosis resulting in a small amount of thickness was observed with less media necrosis. ThreeD and 0D PDT effects reduced with media necrosis. We conclude that PDT after angioplasty would be an ideal preventional therapy of restenosis.

Clinical characteristics in patients showing ischemic electrocardiographic changes during adenosine triphosphate loading single-photon emission computed tomography

OBJECTIVES Although ischemic electrocardiographic (ECG) changes during dipyridamole or adenosine infusion have been reported as a marker for severe coronary artery disease (CAD), few studies have focused on ST-segment changes with adenosine triphosphate (ATP)-loading myocardial single-photon emission computed tomography (SPECT). METHODS AND SUBJECTS Between January 2003 and August 2008, 4650 consecutive patients underwent ATP-loading SPECT. After 1412 patients with left bundle branch block, pacemaker rhythm, or previous coronary revascularization were excluded, 16 out of 3238 patients (0.5%) showed ischemic ST-segment depression during ATP-loading myocardial SPECT. They were aged 67+/-11 years; 10 were men and 6 women. Of these patients, 8 demonstrated perfusion abnormalities, whereas the remaining 8 showed normal myocardial perfusion imaging. In 6 of the 8 patients with abnormal SPECT, coronary angiography was performed, revealing left main trunk disease in 1 patient, 3-vessel disease in 4, 1-vessel disease with proximal left ascending artery occlusion in 1, and an insignificant lesion in 1. By contrast, no major cardiac event was observed in the 8 patients with normal SPECT during follow-up for an average of 2 years. CONCLUSION The prevalence of ischemic ST-segment changes during ATP loading is very rare. However, this finding should be taken into account since almost half of the patients, particularly those with perfusion abnormalities, may have severe CAD which requires coronary revascularization.

The diagnostic utility of the Heston index in gated SPECT to detect multi-vessel coronary artery disease

OBJECTIVES Although the Heston index, derived left ventricular (LV) volumetric analysis, is reported to best represent transient LV dilation on non-gated single-photon emission computed tomography (SPECT), its diagnostic performance has not been proven to identify extensive coronary artery disease (CAD) as assessed by coronary angiogram. Accordingly, we sought to evaluate the diagnostic utility of Heston index to detect multi-vessel CAD. METHODS Post-stress and resting electrocardiogram-gated 99mTc-sestamibi SPECT was performed in 223 patients with suspected or known CAD. All of the patients underwent coronary angiography within 3 months of gated SPECT. The summed stress, summed rest, and summed difference scores were calculated using a 20-segment model. The left ventricular end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF) were calculated automatically with the QGS program. In addition, stress-to-rest ratios of EDV, ESV, and (ESVx5+EDV) were calculated; the latter was defined as Heston index. RESULTS In the 104 patients with multi-vessel CAD, the summed stress score (17.5+/-10.0 vs. 11.7+/-9.2, p<0.001), the summed difference score (9.1+/-6.3 vs. 4.3+/-4.2, p<0.0001), the Heston index (1.17+/-0.15 vs. 1.02+/-0.13, p<0.0001), the stress-to-rest ratio of EDV (1.05+/-0.10 vs. 0.99+/-0.09; p<0.0001), and that of ESV (1.23+/-0.21 vs. 1.04+/-0.17; p<0.0001, respectively) were greater than in the 119 patients with one-vessel CAD or insignificant lesion. The best cut-off value was determined as 1.09 for Heston index, giving a sensitivity of 76%, specificity of 77% for detection of multi-vessel CAD. Multiple stepwise logistic regression analysis showed that Heston index >or =1.09, summed stress score > or =14, and summed difference score > or =9 were the independent predictors of detecting multi-vessel CAD, yielding a sensitivity of 76% and specificity of 77% (global chi 2, 88.8). CONCLUSIONS The Heston index is simple and achieves higher diagnostic value in the detection of multi-vessel CAD, compared with conventional analysis alone.

Evaluation of multidirectional fluorescence-sensing laser catheter for the development of an intelligent laser angioplasty system

The differential diagnostic capacity of a multi-directional sensing catheter with intraluminal objects was evaluated by fluorescence analysis following administration of a photosensitizer. The measurement catheter is 1.7 mm in diameter and is constructed with a cross-sectional arrangement of 6 sensor bundle units and a centered guide wire lumen. Fluorescence was analyzed by polychrometer and amplified CCD camera with an image intensifier. The excitation light was 405 nm wavelength obtained from an Xe-Hg lamp using a band pass filter. In vivo and in vitro fluorescence analysis of normal and atherosclerotic rabbit aorta was performed following intravenous administration of 5 mg/kg hematoporphyrin derivatives (HpD) 24 hours before. The multi-directional sensing catheter detected fluorescence spectra independently in real time. In vivo measurement of this catheter showed, relative to the tip of catheter, in which direction there was blood, normal intima, slight intimal thickness, which should not be treated by laser, or areas of atherosclerosis, which can be treated by laser.