Alex C. Sacharoff

Ultrasound angioscopy: Real-time, two-dimensional, intraluminal ultrasound imaging of blood vessels

The assessment of the presence and severity of disease in the peripheral and coronary arteries currently requires contrast angiography. Although computed tomography, noninvasive ultrasound imaging and fiberoptic angioscopy may allow visualization of certain portions of the arteries, these techniques have limitations.1–3 Contrast angiography, which yields only long-axis images of the blood vessel lumen, continues to be the major diagnostic modality for assessing vascular anatomy. In this report we describe the in vitro and in vivo evaluation of ultrasound angioscopy, a new technique capable of providing dynamic, circumferential images of blood vessels.

Intravascular high frequency two-dimensional ultrasound detection of arterial dissection and intimal flaps

Abstract The anatomy of an arterial lesion has important prognostic and therapeutic implications. Current advances in interventional therapy for coronary and peripheral arterial disease have emphasized the need for more detailed morphologic information on the arterial anatomy than that derived from contrast angiography. Contrast arteriography can display dimensional narrowing of an artery. Other abnormalities such as atheromas, thrombi and dissections are not demonstrated in sufficient detail by arteriography. With fiberoptic angioscopy, some of these abnormalities can be visualized but this technique is cumbersome, requiring intermittent arterial occlusions and injections of clear fluid. Further, arterial wall architecture cannot be evaluated by fiberoptic angioscopy. Among alternate means of imaging an artery, intravascular high frequency ultrasound imaging appears promising. In vitro and in vivo studies from our laboratory and others have shown that catheter-based high frequency intravascular ultrasound imaging can provide information on the arterial wall and luminal size, and detect atheroma. 1–6 Whether this approach can identify arterial abnormalities such as small dissections and intimal flaps, commonly associated with arterial diseases, is not known. In this study we evaluated the potential of intravascular ultrasound imaging in the detection of arterial dissection and delineation of flaps from the arterial wall.

Application of the holmium:YAG laser for refractive surgery III

We report on two clinical trials, one involving 10 patients in the United States and the other in Berlin, Germany with 15 patients, all treated for hyperopia with a new laser surgical procedure known as laser thermokeratoplasty (LTK). The procedure involves making a circular array of corneal coagulations using an Ho:YAG laser, fiber-optic handpiece, and contact focusing tip. The extent of steepening of central corneal curvature is controlled by the diameter of the treatment zone. The LTK procedure induces an immediate and significant reduction in hyperopic refractive error. Although the clinical investigations are at an early stage, results of the clinical trials indicate that the LTK procedure may prove to be a reliable means of effecting a permanent change in refraction in patients suffering from hyperopic refractive disorders.

Application of the holmium:YAG laser for refractive surgery: an update of clinical progress

We describe the results of a 30 patient Phase I clinical trial using the Laser Thermokeratoplasty (LTK) treatment for correction of hyperopic astigmatism. We report the results for 29 patients who have reached 2 months post-operative. The average pre-op cylinder was reduced from -3.06 Diopters (D) to -1.21 D. Average spherical equivalent (SE) refractive error was reduced from +2.28 to +1.34 D. Six patients have reached 4 months post-op; the average cylinder of these patients has been reduced from -1.92 to -0.79 D while the average SE has been reduced from +1.29 to +0.31 D. Although patients had varying degrees of astigmatism pre-op, all treatments were performed with identical parameters (intended to correct a small amount of astigmatism) to enable us to determine the effect of the procedure without the influence of other factors such as varying zone diameter or laser fluence. The predictability and stability of the LTK procedure are supported by a recent study of 20 patients treated in Germany by Seiler for low to moderate degrees (2 - 4 D) of hyperopia. After 6 months post-op, 16 of 20 patients are within +/- 1 D of the attempted correction. Longer-term follow-up will be necessary to determine the ultimate refractive stability of the LTK procedure.