Histopathology of coronary in-stent restenosis following gamma brachytherapy

The histopathology of in-stent restenosis (ISR) following gamma brachytherapy is described. Such histology has not been reported previously. An 82 year old man presented with recurrent ISR three months after gamma brachytherapy to an area of ISR within a native circumflex vessel. The recurrent ISR was treated with directional coronary atherectomy; the histopathology of this directional coronary atherectomy specimen is discussed. These histopathological examinations showed abundant extracellular matrix material. Surprisingly, there was a relatively small cellular (myofibroblastic) component, with an absence of endothelial cells and little evidence of active proliferation. ISR after gamma brachytherapy may be a pathologically distinct entity.

The comparison between optical coherence tomography and intravascular ultrasound

Coronary angiography, despite its long history, has well recognized limitations, arising in part from the inability to image a three dimensional structure in a single plane. Furthermore the angiographic image of the arterial lumen conceals atherosclerotic processes that occur within the arterial wall. Alternative imaging techniques have evolved as an adjunct to angiography in an attempt to overcome these limitations. Two such invasive techniques are intravascular ultrasound and optical coherence tomography. Intravascular ultrasound allows tomographic imaging of long segments of the coronary tree, highlighting the arterial lumen as well as the arterial wall. Over the last 13 years intravascular ultrasound has enhanced our understanding of the pathophysiology of atherosclerosis, and the mechanisms involved in coronary intervention. Optical coherence tomography is an optical analogue of intravascular ultrasound that has recently reached coronary application. Its superior resolution results in improved diagnostic potential, particularly for vulnerable plaque in which the thin fibrous cap often measures 10-50 mm. The similarities, contrasts and applications of these two imaging techniques in terms of design, image interpretation, and future directions forms the subject of this review.