Kazushige Isojima

Clinical validation of intravascular ultrasound imaging for assessment of coronary stenosis severity: comparison with stress myocardial perfusion imaging.

OBJECTIVES To validate intravascular ultrasound (IVUS) measurements for differentiating functionally significant from nonsignificant coronary stenosis. BACKGROUND To date, there are no validated criteria for the definition of a flow-limiting coronary artery stenosis by IVUS. METHODS Preinterventional IVUS imaging (30-MHz imaging catheter) of 70 de novo coronary lesions was performed. The lesion lumen area and three IVUS-derived stenosis indixes comparing lesion lumen area with the lesion external elastic lamina (EEL) area, the mean reference lumen area and the mean reference EEL area were compared with the results of stress myocardial perfusion imaging. RESULTS The lesion lumen area and three IVUS-derived stenosis indexes showed sensitivities and specificities ranging between 80% and 90% using stress myocardial perfusion imaging as the gold standard. The lesion lumen area < or =4 mm2 is a simple and highly accurate criterion for significant coronary narrowing. CONCLUSIONS Quantitative IVUS indices can be reliably used for identifying significant epicardial coronary artery stenoses.

Angioscopy in variant angina : coronary artery spasm and intimal injury

Studies in pigs and dogs show that intimal injury is related to coronary artery spasm; it is not known whether intimal injury is related to coronary artery spasm in human beings. We examined intima at the site of coronary artery spasm by percutaneous transluminal coronary angioscopy in 10 of 13 consecutive patients with variant angina. Coronary artery spasms occurred spontaneously or were induced by intracoronary acetylcholine (10-100 micrograms). Angioscopy showed intimal injuries (haemorrhage, flap, thrombus, or ulcer) in 4 of the 10. We suggest that intimal injury is related to coronary artery spasm in human beings.

Improved regional and global diastolic performance in patients with coronary artery disease after percutaneous transluminal coronary angioplasty

To investigate the improvement of left ventricular (LV) function after successful percutaneous transluminal coronary angioplasty (PTCA), we studied resting ejection fraction, regional ejection fraction, filling fraction as an index of early diastolic performance, and regional filling fraction in 22 patients with single-vessel coronary artery disease and technically adequate LV angiograms before and 6 months after successful PTCA without restenosis. Before PTCA, filling fraction was significantly less in patients with coronary artery disease than in the control group, although there was no significant difference in ejection fraction. Filling fraction improved significantly after PTCA. Regional filling fraction increased significantly in jeopardizing myocardium, but regional filling fraction in nonjeopardized myocardium did not change significantly. Ejection fraction and regional ejection fraction did not change significantly after PTCA. Our results indicate that the improvement of regional diastolic performance in jeopardized myocardium may contribute to the improvement of global diastolic performance after successful PTCA.

Coronary remodeling of proximal and distal stenotic atherosclerotic plaques within the same artery by intravascular ultrasound study

The aim of this intravascular ultrasound study was to compare the type and the degree of vessel remodeling in proximal and distal de novo lesions within the same coronary artery in patients with stable angina pectoris. Seventy-six de novo coronary artery lesions in 38 coronary arteries of 38 patients were imaged by intravascular ultrasound. The vessel area (VA) within the external elastic lamina and the lumen area (LA) were measured, and the wall area (VA-LA) was calculated at the lesion site, and the proximal and distal reference sites. The VA ratio was defined as (lesion VA/average of the proximal and distal reference VAs) to represent the degree of vessel remodeling. The proximal coronary segments showed compensatory enlargement more often (68% vs 29%, p < 0.01) than the distal segments, and the VA ratio at the lesion site was significantly larger (1.1 +/- 0.3 vs 1.0 +/- 0.2, p <0 .01) in proximal segments than in distal segments. The type of coronary remodeling was discordant in 61% and concordant in only 39% of coronary arteries between the proximal and distal segments. The type of coronary remodeling of proximal and distal coronary lesions was inhomogeneous, even within the same vessel. Proximal coronary segments showed more prominent compensatory enlargement than distal segments, which have a similar degree of luminal narrowings.

A Serial Observation of Coronary Thrombi in Vivo by a New Percutaneous Transluminal Coronary Angioscope

This study was undertaken to observe coronary thrombus formation serially from an antegrade perspective by means of a new thin flexible angioscope that has an inflatable balloon at the distal tip and an angulation mechanism. To test its capabilities, thrombi were induced in the left anterior descending coronary artery of 11 dogs by copper coils, and the thrombi were then observed through this angioscope, which had been introduced into the coronary artery by a guide catheter. Five minutes after insertion of the copper coil, fibrin-like material and white components of the thrombi were seen massing around the copper coil. Then, thin, mixed thrombotic white and red components formed around the copper coil. At fifteen minutes after the copper coil insertion, the thrombi grew in size. Ten minutes later, the thrombi finally obstructed the coro nary lumen in most dogs. The red and white appearance of these thrombi was confirmed macroscopi cally, and the microscopic findings of these occluding thrombi revealed a fibrinous network with platelet aggregates and blood cell coagulation. Though ordinary angiography cannot reveal the precise features of the various coronary thrombi, this new angioscope was able to discern them from the antegrade perspective. The capabilities of this angioscope, which enabled these findings, should prove helpful in evaluating the stages of human coronary thrombosis. Of additional benefit, this angioscope can be used clinically for cardiac catheterization.

Effect of Quinapril versus Nitrendipine on endothelial dysfunction in patients with systemic hypertension

linearly related to CAD severity in women, which likely explains the stronger association with clinical events and mortality. No such relation was observed for men. In women, CAD was predicted by metabolic syndrome risk factors, and the association with uric acid reflects this risk factor pattern. Regardless of whether hyperuricemia is an independent risk factor, it identifies a high-risk subset of women. For men, the best predictors of CAD were advanced age and microalbuminuria.

Angioscopy, coronary thrombi and acute coronary syndromes

Coronary angioscopy is a new diagnostic imaging technique in which optic fibres are used to directly observe the intracoronary lumen. Angioscopy provides a full colour, high resolution, three-dimensional image of the intracoronary artery surface morphology. Studies using angioscopy revealed that the frequency of coronary thrombi in patients with acute coronary syndromes was higher than previous studies, based on arteriography, had reported. Arteriographic recognition of thrombus in unstable angina was from 1.3% to 52%. On the other hand, thrombi were observed in 88% by angioscopy in patients with rest angina in our study. Whereas ordinary arteriography provides only two-dimensional black and white images, angioscopy can distinguish between a thrombus and a plaque, even if the clot is very small. In a study of 17 unstable angina and 22 myocardial infarction patients, the frequencies of coronary thrombi in the two groups were essentially the same. Grayish-white thrombi were observed in most of the unstable angina patients but in none of the infarction patients. On the other hand, red or mixed red and white thrombi were observed in all infarction patients but in only a few unstable angina patients. This difference may account for the contrasting results of thrombolytic therapy.

Laser Angioplasty Using Carbon Monoxide Lasers

In this paper, we demonstrate the possibility as well as usefulness of the usage of CO lasers for the laser coronary angioplasty. CO lasers, approximately 5μm of their wavelength, have strong ablation capacity to water-containing living tissue due to intensive attenuation by water. Accordingly, a precise ablation of intravascular obstruction without a perforation may be possible by the CO laser irradiation. As a fundamental study, the design of the fiber energy delivery of CO lasers for the coronary angioplasty and the ablation effect of the CO laser irradiation to human atheroma are revealed. The CO laser irradiation method in the flushing medium of a coronary angioscope is also discussed.

Utility and limitation of treadmill exercise echocardiography for detecting significant coronary stenosis in infarct-related arteries in patients with healed myocardial infarction.

This clinical study examines the diagnostic accuracy of exercise echocardiography for detecting significant coronary stenoses in infarct-related arteries in patients with healed myocardial infarction. Quantitative coronary angiography and exercise echocardiography using treadmill testing were performed within 2 weeks of each other in 123 patients with a prior myocardial infarction. Coronary lumen diameter stenosis > or =50% by quantitative coronary angiography and the lack of a hyperdynamic response on exercise echocardiography was considered significant. For detection of infarct-related coronary lesions, treadmill exercise echocardiography was highly sensitive (91%) but less specific (59%) than for detection of non-infarct-related artery lesions. The 2 groups of patients with large and small infarct sites had similar sensitivity for detection of residual stenosis of the infarct-related artery (88% vs 96%, p = NS); however, the specificity of the small infarct sites for this purpose was significantly higher than that of the large infarct sites (86% vs 33%, p < 0.01). When remote ischemia was detected on exercise echocardiography, the specificity of exercise echocardiography was significantly lower (33% vs 70%, p < 0.05) than when remote ischemia was not present. Thus, although there is high sensitivity, the specificity of treadmill exercise echocardiography for detecting infarct-related artery lesions is limited. However, high specificity is maintained when the infarct size is small and/or remote ischemia is not present.

Laser coronary angioplasty using carbon monoxide lasers

A study was made of a laser angioplasty system using a CO laser, 5 mu m in wavelength. To achieve therapeutic irradiation in a water solution, the authors developed a contact CO laser irradiation method which uses an optical fiber to carry the laser beam to the lesion. The authors have also developed a thin coronary angioscope catheter for diagnosis and targeting of this therapy.<<ETX>>