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Recently, the use of ionizing radiations has received much interest as a new treatment tool to reduce restenosis after angioplasty or stent implantation. There are two main approaches for delivering endovascular radiation: one is based on gamma or beta sources with very high activities to deliver locally through a catheter the dose in a limited period of time. The other approach is based on a stent rendered radioactive for long exposure and continuous low-dose rate treatment. External radiation is also contemplated but indications seem more oriented towards the peripheral vascular system. After a brief introduction to fundamentals of radiobiology, radiation physics and radioprotection, we review the experimental data which have led to large ongoing multicenter trials. The results of these trials involving more than 2000 patients will be available in the next few years and will allow to better define the risk/benefit ratio of this potentially new indication for radiotherapy.

Intravascular ultrasound (IVUS) is an imaging method which uses one or several ultrasound transducers at the tip of catheters to visualize the morphology of arteries. IVUS was developed to provide precise information not only about arterial stenoses, but also about atherosclerotic lesions and lesions of the vessel wall. Indications for IVUS are currently being developed. One application is for the evaluation of disease of the common trunk when a doubt persists after angiography. Ambiguous lesions on angiography, particularly situated at coronary bifurcations, can also be clarified by IVUS. The precise evaluation of the real extent of atherosclerosis by IVUS makes it an ideal tool for clinical trials of regression of coronary disease. It also provides a better understanding of the apparent paradox between the minimal reduction of atheromatous plaques on angiography and the dramatic reduction of coronary events. IVUS is extremely useful to elucidate the mechanisms and complications of percutaneous interventional procedures. For example, IVUS allows a better understanding of restenosis after angioplasty (whether it is due to intimal proliferation or to vascular remodelling), elastic recall and sudden occlusion. In view of the large atheromatous mass visible on IVUS at the dilated site even after an angiographically adequate operation, insufficient angioplasty can be considered to be the third mechanism contributing to restenosis. This finding has important clinical implications, as ultrasound guidance could possibly result in better short-term and medium-term results of angioplasty. IVUS could also allow better selection of the type of operation in these patients. IVUS is also useful to facilitate adequate deployment of coronary stents, as angiographic criteria predicting ultrasonographically adequate expansion of the stent have still not been developed. By complementing angiography for the diagnosis of atheromatous disease and by monitoring percutaneous coronary operations, the role of IVUS as a clinically useful tool should continue to grow over the next few years.

Nitrates continue to play a key role in the treatment of heart disease. Tolerance can be prevented if treatment is interrupted for periods of eight to 14 hours. Because patients respond differently to nitrate therapy, consideration must be given to individual response, the risk of tolerance, and the method of administration.