-
[show abstract]
[hide abstract]
ABSTRACT: We investigate the relation between the influences on smooth muscle cells and the chronic performances of our novel short-duration heating balloon dilatation to reveal the heating conditions which can suppress the neo-intimal hyperplasia after our heating dilatations. The temperature of prototype balloon catheter surface was measured during short-duration heating balloon dilatation ex vivo. There existed 2 °C temperature variations in the long direction of prototype balloon catheter at a maximum. The neo-intimal hyperplasia occupancy rate after our short-duration heating dilatations were measured in vivo porcine study. The neo-intimal hyperplasia was suppressed most at 75 °C in balloon peak temperature in vivo. The estimated dead rate of smooth muscle cells at this condition was about 13% by the Arrhenius equation. We think that the suppression of neo-intimal hyperplasia was obtained after our short-duration heating dilatation due to the proper decrease of smooth muscle cells by heating and no thermal damages to the adventitia and surrounding tissues.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2011; 2011:349-52.
-
[show abstract]
[hide abstract]
ABSTRACT: We proposed a novel laser-driven short-term heating angioplasty to realize restenosis-suppressive angioplasty for peripheral artery disease. In this study, we investigated the chronic intimal hyperplasia formation after the short-term heating dilatation in vivo, as well as the thermal damage calculation on arterial smooth muscle cells (SMCs). The prototype short-term heating balloon catheter with 5.0, 5.5, 6.0 mm φ in balloon diameter and 25mm in balloon length were employed. The short-term heating dilatation was performed in porcine iliac arteries with dilatation conditions of 75°C (N=4) and 65°C (N=5) as peak balloon temperature, 18± 4s as heating duration, 3.5atm as balloon dilatation pressure. Four weeks after the balloon dilatation, the balloon-dilated artery segments were extracted and were stained with HE and picrosirius red for histological observation. In the case of 75°C as the peak balloon temperature, neointimal hyperplasia formation was significantly reduced. In this case, the SMCs density in the artery media measured from the HE-stained specimen was 20% lower than that in the reference artery. According to the thermal damage calculation, it was estimated that the SMCs lethality in artery media after the short-term heating angioplasty was 20% in the case of 75°C as the peak balloon temperature. We demonstrated that the short-term heating dilatation reduced the number of SMCs in artery media. We think this SMCs reduction might contribute to the suppression of chronic neointimal hyperplasia.
Engineering in Medicine and Biology Society (EMBC), 2010 Annual International Conference of the IEEE; 10/2010
-
[show abstract]
[hide abstract]
ABSTRACT: Excessive vascular damage causes excessive vascular repair, which results in restenosis. To limit the thickness of the coagulation layer in laser balloon angioplasty, we used a carbon monoxide (CO) laser, which has high tissue absorption, as a therapy laser source instead of a Nd: YAG laser. To investigate the benefit of short-penetration CO laser light to vascular tissue, excised human abdominal aorta was irradiated with a CO laser through a 30 microns polyethylene membrane. The temperature of the vascular tissue was continuously monitored during irradiation. CO laser irradiation of 20 W/cm2 was performed in either a continuous mode or an intermittent mode with various duty ratios (exposure/interval duration). With a total fluence of 200 J/cm2, the adventitial temperature decreased as the duty ratio was reduced. The adventitial temperature at a duty ratio of 1:2 was 43 degrees C. Microscopic examination of aorta which had been intermittently irradiated duty ratio of 1:2 showed thermal coagulation localized within the intima and a flattened intimal surface. These results suggest that intermittent laser irradiation with a CO laser can be used to limit the depth of thermal coagulation, and can selectively weld the intima without excessive thermal damage. Laser balloon angioplasty using a CO laser may help to prevent restenosis.
Japanese Circulation Journal 09/1993; 57(8):825-31.
-
[show abstract]
[hide abstract]
ABSTRACT: To investigate the pathogenesis of acute coronary disorders and to clarify what type of plaque precedes these disorders, percutaneous transluminal coronary angioscopy, by means of a new angioscope, was carried out during catheterisation in 100 consecutive patients anatomically suitable for such investigations. The quality of the angioscopic image was good enough for analysis in 84 patients (14 with acute myocardial infarction [within 8 h of onset], 16 with recent myocardial infarction [3 days-2 months since onset], 24 with old myocardial infarctions, 10 with unstable angina, and 20 with stable angina). Thrombi were observed in most patients with acute coronary disorders (all 14 with acute myocardial infarction, 9 of 10 with unstable angina). Occlusive thrombi were more common in patients with acute myocardial infarction than in those with unstable angina (11 [79%] vs 1 [10%]; p less than 0.001), whereas mural (non-occlusive) thrombi were more common in the unstable angina than in the acute myocardial infarction group (8 [80%] vs 3 [21%]; p less than 0.001). Xanthomatous ulcerated plaques or ragged irregular surfaces were seen in patients with acute coronary disorders and in those with recent myocardial infarction. Xanthomatous plaques were more common in patients with acute coronary disorders (50%) than in those with stable angina (15%) or old myocardial infarction (8%). By contrast white and smooth plaques were seen in cases of stable angina and old myocardial infarction. Angioscopy could display the intracoronary lumen more precisely than could coronary arteriography. This angioscopic study suggested that, although a thrombus overlying a rupture in the lining of the plaque was common in both unstable angina and acute myocardial infarction, the character of the thrombus may differ between these disorders, and lipid-rich xanthomatous plaque may precede rupture.
The Lancet 05/1991; 337(8745):809-12. · 38.28 Impact Factor
