Tsutomu Tamura

Luminal loss and site of restenosis after Palmaz-Schatz coronary stent implantation

Restenosis has frequently been observed at the articulation of the Palmaz-Schatz stent. However, the precise mechanism for this remains poorly understood. We measured the luminal diameter in 5 segments within the stent in 67 lesions of 63 patients with successful stenting. Luminal diameter at all 5 sites was significantly reduced 6 months after stent implantation (3.2 +/- 0.5 vs 2.4 +/- 0.7 mm, p < 0.05). Angiographic restenosis rate was 18%. Restenosis involving the articulation was found in 75% of the lesions, and that involving the articulation or edges in 83%. The diameter at the articulation was significantly smaller both immediately (3.0 +/- 0.5 mm vs 3.3 +/- 0.5 mm, p < 0.05) and 6 months after (2.1 +/- 0.8 mm vs 2.5 +/- 0.7 mm, p < 0.05) stenting than the diameter of other stent segments. The loss index was significantly greater at the proximal and distal edges than at the bodies of the stent (0.98 vs 0.60, p < 0.05). The edges of the Palmaz-Schatz stent tend to dilate more than the body of the stent during normal inflation. Although this anchoring system protects against dislodgment or migration of the stent, it may cause more injury. The articulation has 2 anchoring edges within only a 1 mm diameter. Thus, restenosis at the articulation may be ascribed to residual stenosis, increased intimal proliferation due to more severe injury, and delayed late vessel remodeling from lack of mechanical support. These characteristics may be attributed to stent design, and design improvement of the articulation may lead to more favorable results after stent implantation.

Effects of cilostazol on late lumen loss after Palmaz-Schatz stent implantation

Cilostazol inhibits intimal hyperplasia after stent implantation into canine iliac arteries. To determine the antiproliferative effect of this agent, cilostazol or aspirin was randomly given for 6 mo to 36 patients treated with Palmaz-Schatz stent implantation. Initial success was obtained in 34 patients. Repeat angiography was performed in 33 patients, and the complete angiographic data were obtained in 22 lesions of the cilostazol group and in 21 lesions of the aspirin group. The reference diameter and minimal luminal diameter were similar in both groups before and immediately after stent implantation. At follow-up, minimal luminal diameters were significantly greater in the cilostazol group than in the aspirin group (P < 0.001). Late loss and loss index were significantly smaller in the cilostazol group than in the aspirin group (P < 0.001). These results suggest that cilostazol reduces angiographic late lumen loss and thereby may reduce the incidence of restenosis after Palmaz-Schatz stent implantation.

Initial and subsequent angiographic outcome of percutaneous transluminal angioplasty performed on internal mammary artery grafts.

OBJECTIVE--To estimate the initial outcome and incidence of restenosis of angioplasty of internal mammary artery grafts in a retrospective study. METHODS--The study population consisted of 46 patients (48 lesions) who underwent first balloon angioplasty within the internal mammary artery graft. Most (37/48) were at the distal anastomosis. A few (8/48) were in the graft body. Six patients with the evidence of angiographic restenosis underwent a second angioplasty. RESULTS--The success rate and the restenosis rate of the first angioplasty was 73% and 30% respectively. Of the 34 patients (35 lesions) with a successful first angioplasty, 30 underwent follow up angiography with a restenosis rate of 30% (9/30). A second angioplasty was performed on six of the nine restenotic lesions, with a success rate of 83% and no restenoses. The percent diameter stenosis of the recipient native coronary artery was significantly greater in the restenosis group, at 75 (SD 27)% v 89 (17)%, p < 0.05. CONCLUSIONS--First angioplasty of 46 patients (48 lesions) within an internal mammary artery graft was performed with a success rate of 73% and a restenosis rate of 30% (follow up rate of 88%). The extent of the stenosis of the recipient native coronary artery may affect the restenosis rate.

Novel guide catheter for left coronary intervention via a right upper limb approach

We designed a novel guide catheter specifically for interventions to the left coronary artery via a right upper limb approach. The catheter has a novel first loop design which utilizes the angle between the right subclavian and innominate arteries for support. The first loop introduces the catheter into the correct position and generates powerful and coaxial back-up power. We report successful implantation of Palmaz-Schatz stents in five cases using this 6 Fr. catheter.

New long-tip guiding catheters designed for right transradial coronary intervention.

New long‐tip catheters, one for the left and the other for the right coronary artery, were designed specifically for right transradial intervention. We utilized the overbending principle to achieve more precise control of the catheters. We also analyzed principal factors involved to determine guiding catheter support considering the anatomy of the innominate artery, ascending aorta, left and right coronary arteries. Catheter shapes were designed to exploit favorable factors to compensate for mechanically disadvantageous anatomy. The catheter for the left coronary artery has an initial loop to make use of the angle between the innominate artery and the ascending aorta to introduce the catheter to the correct position to provide strong backup support. The catheter for the right coronary artery has a unique three‐dimensional curve that provides sufficient backup support and compensates for the angles between the innominate artery and the proximal portion of right coronary artery to achieve coaxial engagement. The distal portions of these catheters include long tips aiming to minimize the loss of transmitted force. The performance of these catheters was studied in 143 patients with 161 lesions. Successful engagement was achieved in 138 patients with 156 lesions (97%) and coronary intervention was successful in 136 patients with 154 lesions (99%). No major complications or coronary artery dissection occurred due to use of these catheters. This study showed the present long‐tip catheters to be safe and highly effective for right transradial coronary intervention. Cathet. Cardiovasc. Intervent. 49:218–224, 2000.

Transluminal extraction atherectomy for restenosis following Palmaz-Schatz stent implantation.

Transluminal extraction atherectomy with adjunctive balloon angioplasty was successfully performed in 9 patients who had restenosis after Palmaz-Schatz stent implantation. Although 4 patients with either totally occluded lesions or with saphenous vein graft lesions had recurrence, this strategy may be a potential treatment for in-stent restenosis.

Tyrosine phosphorylation of platelet derived growth factor β receptors in coronary artery lesions: implications for vascular remodelling after directional coronary atherectomy and unstable angina pectoris

Background Growth factors such as platelet derived growth factor (PDGF) have been postulated to be important mediators of neointimal proliferation observed in atherosclerotic plaques and restenotic lesions following coronary interventions. Binding of PDGF to its receptor results in intrinsic receptor tyrosine kinase activation and subsequent cellular migration, proliferation, and vascular contraction. Aims To investigate whether the concentration of PDGF β receptor tyrosine phosphorylation obtained from directional coronary atherectomy (DCA) samples correlate with atherosclerotic plaque burden, the ability of diseased vessels to remodel, coronary risk factors, and clinical events. Methods DCA samples from 59 patients and 15 non-atherosclerotic left internal thoracic arteries (LITA) were analysed for PDGF β receptor tyrosine phosphorylation content by receptor immunoprecipitation and antiphosphotyrosine western blot. The amount of PDGF β receptor phosphorylation was analysed in relation to angiographic follow up data and clinical variables. Results PDGF β receptor tyrosine phosphorylation in the 59 DCA samples was greater than in the 15 non-atherosclerotic LITA (mean (SD) 0.84 (0.67) v 0.17 (0.08) over a control standard, pu2009<u20090.0001). As evaluated by stepwise regression analysis, incorporation of both PDGF β receptor tyrosine phosphorylation and immediate gain correlated strongly (adjustedr 2u2009=u20090.579) with late loss, although PDGF β receptor tyramine phosphorylation alone correlated poorly with late loss. Multivariate regression analysis of coronary risk factors and clinical events revealed unstable angina as the most significant correlate of PDGF β receptor tyrosine phosphorylation (F value 20.009, pu2009<u20090.0001). Conclusions PDGF β receptor tyrosine phosphorylation in atherosclerotic lesions is increased compared with non-atherosclerotic arterial tissues. The association of PDGF β receptor tyrosine phosphorylation with immediate gain strongly correlates with vascular remodelling. PDGF β receptor tyrosine phosphorylation correlates with unstable angina pectoris.

Percutaneous angioplasty of stenosed gastroepiploic artery grafts

OBJECTIVESnThis report describes our early experience and results with percutaneous transluminal coronary angioplasty of gastroepiploic artery grafts in 12 patients.nnnBACKGROUNDnAngioplasty has been successfully performed in saphenous vein and internal thoracic artery grafts; however, experience with angioplasty in gastroepiploic artery/coronary artery bypass grafts is limited.nnnMETHODSnBalloon angioplasty was performed in 12 patients (11 men, 1 woman; mean age 58 +/- 8 years) with either total occlusion (6 patients) or severe stenosis (6 patients) of a gastroepiploic artery/coronary artery anastomosis. In seven patients, a guide wire/balloon catheter system was used through a 7F sheath inserted into the celiac trunk. In seven patients, including two who had unsuccessful wire/balloon angioplasty, an over the wire system was used through a 6.5F Cobra or 7F JR4 guide catheter, selectively inserted into the gastroduodenal artery.nnnRESULTSnAngioplasty was successful in five (83%) of six patients with stenosis and in one of six patients with total occlusion (p = 0.08, 1 - beta = 0.68). The guide wire could not be advanced through the lesion in five patients, and the balloon catheter did not cross the lesion in one patient whose gastroepiploic artery was tortuous. Catheters exhibited better trackability and pushability when the over the wire system was used, and five of the six successes were achieved using this approach. Follow-up arteriography was performed in five patients, and all of the gastroepiploic artery grafts were patent without stenosis.nnnCONCLUSIONSnAngioplasty can be safely performed in stenosed gastroepiploic artery grafts. An over the wire system that uses a thin balloon catheter inserted through a guide catheter in the gastroduodenal artery seems optimal.

Thrombotic occlusion of the coronary artery associated with accidental detachment of undeployed Palmaz‐Schatz stent

We describe a case of coronary stenting in which accidental detachment of the Palmaz-Schatz stent induced thrombotic occlusion of the coronary artery. This case suggests that careful consideration of the risk involving coronary occlusion is mandatory on deciding the therapeutic strategy of the cases in which the unexpanded coronary stent cannot be retrieved following successful deployment.

Stent placement in surgically reimplanted left main coronary artery in patient with anomalous origin of left main coronary artery from pulmonary artery.

Surgical repair of a 29-year-old womans left coronary artery with an anomalous origin from the pulmonary artery was performed by reimplantation of the left main artery into the aorta, together with coronary artery bypass grafting. Subsequent stenosis of the reimplanted left main artery was treated with successful Palmaz-Schatz stent placement.