Ko Arakawa

Angioscopic Evaluation of Coronary-Artery Thrombi in Acute Coronary Syndromes

BACKGROUND Disruption of an atherosclerotic plaque in a coronary artery followed by the formation of a thrombus is believed to be the cause of both unstable angina and acute myocardial infarction. Although thrombolytic therapy is efficacious in patients with acute myocardial infarction, for unknown reasons it is far less effective in patients with unstable angina. We postulated that there might be differences in the composition of the coronary-artery thrombi in unstable angina and acute myocardial infarction. METHODS To investigate the appearance of coronary-artery thrombi, we performed percutaneous transluminal coronary angioscopy in 15 patients with unstable angina and 16 with acute myocardial infarction. Angioscopy was performed within 48 hours after an episode of pain at rest in the patients with unstable angina and within 8 hours of onset in those with acute myocardial infarction. RESULTS Angioscopy revealed coronary thrombi in all but two patients (one in each group). Of the 29 patients with thrombi, those with unstable angina were frequently observed to have grayish-white thrombi (10 of 14, 71 percent), but none were seen in the 15 patients with acute myocardial infarction (P less than 0.01). By contrast, reddish thrombi were observed in all 15 patients with acute myocardial infarction who had thrombi, but in only 4 of the 14 patients with unstable angina and thrombi (P less than 0.01). As assessed by coronary angiography, occlusive thrombi occurred frequently in patients with acute myocardial infarction (13 of 16 patients) but were not seen in any of the 15 patients with unstable angina (P less than 0.01). CONCLUSIONS Coronary-artery thrombi play an important part in the pathogenesis of unstable angina and acute myocardial infarction. However, the appearance of the thrombi is different in the two conditions, possibly reflecting differences in the composition of age of the thrombi or the presence or absence of blood flow in the artery. This difference may account for the contrasting results of thrombolytic therapy.

New percutaneous transluminal coronary angioscope

Abstract A new percutaneous transluminal coronary angioscopic catheter has been developed for visualization of the coronary artery. A specially made balloon, fixed at the catheter tip, and an angulation mechanism made a precise coaxial alignment possible in the coronary lumen. This angioscopic catheter, 1.22 mm in outer diameter, has four channels, one for irrigation in which a 0.36 mm (0.014 in.) angioplasty guide wire can be used. With the use of this angioscope, coronary lumens in 8 dogs, thrombi that were produced with copper coils in the left anterior descending coronary artery in 11 dogs, atherosclerotic coronary arteries in 20 patients during cardiac catheterization and the sequence of transluminal coronary angioplasty in 1 patient were observed. The angioscopic catheter was introduced into the coronary artery by an 8F guide catheter. The steerable guide wire enabled the angioscopic catheter to be accurately and safely inserted into the target lesion in all cases. The inflated balloon and angulation mechanism allowed a curved coronary lumen and atheroma to be seen with a limited volume of irrigation fluid. Visualization was good (complete visualization of the inner lumen) in 46% (10 of 22 lesions), moderate (visualization of >50% of the inner lumen) in 36% (8 of 22 lesions) and poor (visualization of These preliminary experiences in closed chest cardiac catheterization in dogs and in humans indicate the feasibility of this angioscope. The information yielded by angioscopy may be clinically useful in the study of the pathophysiologic changes in coronary disease that are not detected by coronary arteriography.

Role of coronary collateral vessels during transient coronary occlusion during angioplasty assessed by hemodynamic, electrocardiographic and metabolic changes

The clinical role of collateral vessels was evaluated during transient coronary occlusion by percutaneous transluminal coronary angioplasty in 22 patients with (8) and without (14) collateral vessels. Coronary occlusion pressure, the ratio of mean coronary occlusion pressure to mean aortic pressure and myocardial perfusion pressure at 40 s of balloon inflation were significantly higher in patients with than in patients without collateral vessels. The changes in left ventricular systolic and end-diastolic pressure, maximal rate of rise of left ventricular pressure (peak dP/dt) and maximal rate of fall of left ventricular pressure (negative peak dP/dt) during balloon inflation were less in patients with than in patients without collateral vessels. Myocardial lactate was produced in patients without collateral vessels but not in those with such vessels. Marked ST segment elevation in the electrocardiogram occurred in patients without collateral vessels but either ST segment depression or mild ST segment elevation was observed in patients with collateral vessels. This study indicates that collateral vessels limit myocardial ischemia during coronary occlusion, probably as a result of increased myocardial perfusion pressure.

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.

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.

Increased Triglyceride May Determine the Sites of Coronary Arterial Lesions

There is much controversy on the significance of elevated triglyceride in the development of coronary atherosclerosis. Many epidemiological studies indicate that triglyceride is not an independent risk. However, clinical studies or in vitro studies suggest that triglyceride or certain triglyceride-rich lipoproteins might be atherogenic. In order to clarify the clinical significance of hypertriglyceridemia, we compared angiographic findings in the patients with various types of hyperlipidemia.

New Percutaneous Transluminal Coronary Angioscope

A new thin coronary angioscope which has a inflatable balloon at its distal tip is described in this paper. This angioscope is formed into very thin flexible catheter, less than 4F(1.33mm) in sheath outer diameter at the catheter tip. The angioscope contains two penetrated lumina which utilize for either flushing blood or manipulating of a guiding wire. A selective intracoronary visualization in left anterior descending coronary artery (LAD) and circumuflex(CX) of dogs up to 15kg in their weight were carried out during up to 20s until occurring of ST segment change of the electro-cardiogram(ECG).