The Study of Dwelling Time Design in Beta-Radiation to Prevent Restenosis after Percutaneous Transluminal Coronary Angioplasty

經皮冠狀動脈血管形成術(Percutaneous Transluminal Coronary Angioplasty; PTCA)是種有效治療冠狀動脈阻塞的方法[1]，目前最大的難題及限制爲在六個月內通常有30至50%之再狹率(restenosis rate)[2,3]，再狹窄的機轉是因爲血管新內膜的增生與管壁彈性退縮。因此，冠狀動脈支架的植入可減低其彈性退縮的可能性，但內膜的增生仍無法解決[4,5]。最近，在以伽瑪射線在冠狀動脈內照射可證明減少內膜之增生以減少血管狹窄之機率[6]。但是，因伽瑪同位素射源的穿透力強及輻射防護困難，其使用上有所限制。在對輻射安全的考慮上，貝它射線被認爲是一種較安全之取代方法，使用貝它射源做照射也可達到相同功效，而動物實驗證明，貝它射源可減低內膜的增生及再狹窄機率[8]。美國哥倫比亞大學最早使用液態錸－188射源，其爲貝它射線，總能量在2.13MeV，平均貝它能量爲0.771mMeV，在哥大的同意及技術協助下，我們將對120名接受PTCA病患做隨機抽樣研究，60名病患經PTCA後接受貝它射線照射，另60名經PTCA病患接受安慰劑（沒有放射線）的處理。我們評估在6個月內可收集120名病患。在追蹤過程中，需評估病患主要臨床症狀包括復發性心肌缺血症狀，目標血管導致的心肌梗塞及同一病灶需要再次做冠狀動脈治療，以及病患死亡等可能發生之情況。在PTCA後六個月，病人將接受冠狀動脈血管照相及血管內超音波檢查，對經照射狹窄部位做評估，包括其是否有再狹窄及血管內膜之增長情形。本研究的最終結果是希望觀察經照射後30天的安全性與及經六個月後血管的再狹窄率。我們預期此技術之應用能減低再狹窄率而不致增加病患的任何副作用。

關鍵字

近接治療；貝它射源；伽瑪射源；多分子膠質體；治療時間計算系統

並列摘要

Percutaneous transluminal coronary angioplasty (PTCA), as an effective modality of treating obstructive coronary artery disease [1], is limited by a 30-50% restenosis rate within 6 months after the procedure [2,3]. The mechanism of rest enosis involves elastic recoil and neointimal hyperplasia. Though, intracoronary stent implantation eliminates the mechanical recoil of the post-PTCA vessel, intimal hyperplasia remains an unsolved problem [4,5]. Recent1y, studies using intracoronary gamma radiation have shown to reduce intimal hyperplasia and restenosis rate strikingly [6]. However, the gamma radiation isotope has serious limitations for use in human coronaries because it is deeply penetrating and not effectively shielded by standard lead apron. For the radiation safety consideration, beta-radiation is considered to be a much safer alternative. Likewise, beta-radiation delivered to the animal coronary arteres have also shown to reduce intimal hyperplasia and restenosis rate [7,8]. Preliminary clinical trial using Rhenium-188 (Re-188) solution, a beta-minus emmiter with a transition energy of 2.13 MeV, mean beta ray energy of 0.77MeV, has already been initiated in Columbia University, U.S.A.. We have acquired the technical assistance from Columbia University to conduct a randomized placebo control study in a total of 120 patients with PTCA-indicated patients. Sixty patients will receive beta-radiation after PTCA and the 60 patients will be the placebo-control group received no radiation after PTCA. We estimate that 120 patients will be accrued within 6 months. Regular follow-ups will be conducted to evaluate the major clinical events, recurrent ischemic symptoms, death, target vessel myocardial infarction, or target vessel revascularization. Coronary angiography and intravascular ultrasound will be performed at 6 months after the procedure to assess the angiographic restenosis rate and degree of intimal hyperplasia. The primary study endpoints are 30-day safety and 6 months angiographic restenosis rate. We expect this approach will reduce the restenosis rate at a highly statistical significant level and it will not pose any additional risk to the patients.

並列關鍵字

brachytherapy ； gamma and beta emitters ； dwelling time design

國際替代計量

The Study of Dwelling Time Design in Beta-Radiation to Prevent Restenosis after Percutaneous Transluminal Coronary Angioplasty

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