Rintaro Nakajima

Chronic stent recoil plays an important role in restenosis of the right coronary ostium.

ObjectiveThe efficacy of coronary stenting of aorto-ostial atherosclerotic lesions is still unclear. We investigated the frequency and mechanism of stent restenosis at this particular lesion. MethodsFifty-five consecutive patients with 64 native aorto-ostial lesions in the right coronary artery (RCA, n=38) and the left main trunk (LM, n=26) were treated by conventional stenting. Determinants of angiographic restenosis were established. The mechanism of stent restenosis was evaluated using post-stenting and follow-up intravascular ultrasound (IVUS) findings. ResultsRestenosis was more frequent in the RCA than in the LM (50% compared with 19%, P<0.03) and determinants included diabetes mellitus (63% compared with 21%, P<0.03), calcium deposition (58% compared with 5%, P<0.003), smaller stent cross-sectional area (SA) (as demonstrated by post-stenting IVUS studies, 8.1±1.4 mm2 compared with 10.2±2.2 mm2, P<0.01), larger plaque burden (64±6% compared with 57±8%, P<0.03) and less circular expansion at the aorto-coronary junction. Serial IVUS examination was performed in 11 patients with restenosis of the right coronary ostium. The mean reduction in the SA was 21% at the aorto-coronary junction (6.4±1.9 mm2, P<0.003), whereas the SA at the distal edge was unchanged. Thirty-three per cent of late luminal loss was due to chronic stent recoil. ConclusionThese findings suggest that stenosis of the right coronary ostium is a high-risk lesion for stent restenosis. In addition to excessive intimal growth, chronic stent recoil might be an important etiologic factor at this particular location.

Ultrasound attenuation behind coronary atheroma without calcification: Mechanism revealed by autopsy

When performing intravascular ultrasound studies, the backward echo image can show marked attenuation, although there are no calcified deposits and it may be impossible to detect the intraplaque architecture. The pathology underlying this phenomenon was investigated in autopsy specimens. We hypothesize that the mechanism responsible for the attenuation involves micro‐calcification and lipid in unstable plaques causing ultrasonic wave reflection and dispersion.

Stent deformation: an experimental study of coronary ostial stenting☆

OBJECTIVES To investigate stent deformation by torsional stress after implantation at the ostium of a model coronary artery. BACKGROUND Little is known about coronary stent deformation, especially the association between stent design and deformation at the coronary ostium. Recent reports have suggested that mechanical factors are important for stent restenosis. METHODS A coronary ostium model was constructed and three different stents (Express(2), Cypher, and Tsunami, n=5 each) were implanted at the aorto-ostial junction. Differences of stent deformation were assessed after exposure to torsional stress. Intravascular ultrasound was used to measure the luminal area along each stent. Then the extent and pattern of plastic deformation were compared between the three stent types. RESULTS The Express(2) stents and Cypher stents both showed significant deformation (P<.0001 and P=.045, respectively) adjacent to the ostium, whereas only a minimal decrease of luminal area was observed with the Tsunami stent. In the central and distal parts of each stent, the decrease of luminal area was minimal and no differences were noted among the three types. Sudden fracture of a Cypher stent strut occurred during the experiment. CONCLUSION Differences of structural characteristics influence permanent plastic deformation at sites where continuous stress occurs, such as the coronary ostium. A more elastic design may show better resistance to such stress.

Insulin resistance and acute coronary syndrome in the young Japanese population have a strong association

There are few data regarding acute coronary syndrome (ACS) in young Japanese patients. We examined the risk factors for ACS in young Japanese patients, especially impaired glucose metabolism. From a database of 789 consecutive patients admitted to our hospital with ACS between 2000 and 2005, we compared risk factors of patients divided into two age categories: ≤45 years (group Y, n = 41) and ≥46 years (group O, n = 748). All patients in group Y were male. Overt diabetes, hypertension, and a family history of ischemic heart disease were not so important to group Y. Higher triglyceride (160.5 ± 86.0 vs 133.9 ± 75.2 mg/dl, P = 0.0296) and lower high-density lipoprotein cholesterol (43.9 ± 12.1 vs 48.7 ± 13.5 mg/dl, P = 0.027) concentrations were present in group Y. We obtained data concerning insulin resistance in 326 of 789 patients. Although the incidence of impaired glucose tolerance was similar between the groups (31% vs 31%, not significant), a higher homeostasis model assessment insulin resistance index (2.26 ± 2.03), indicating insulin resistance, was present in group Y. Insulin resistance might be correlated with the development of ACS in the young adult Japanese population.

A case of acute myocardial infarction treated with a new thrombectomy system.

Thrombotic occlusion in the culprit lesion of acute myocardial infarction was successfully recanalized using a 4.5 Fr thrombectomy catheter (RESCUE), which was also used to normalize the coronary blood flow. The retrieved specimens were white thrombi containing red thrombi and cholesterol crystals, indicating plaque rupture. Cathet Cardiovasc Intervent 2002;55:239–243.

An example that presented giant aneurysm of the angina pectoris after percutaneous coronary intervention.

We present the case of a 70-year-old woman who was admitted to our hospital with heart failure due to a giant left ventricular aneurysm involving the apex and severe mitral regurgitation. Three months before the hospitalization, percutaneous coronary intervention was performed for severe stenosis of the left main trunk. During the procedure, there were no abnormalities of distal coronary flow due to problems like embolization, and repeat coronary angiography, performed after stabilization of heart failure, showed no new significant stenosis. We diagnosed her condition as a subepicardial aneurysm by pathological examination of the resected specimen.