Angioscopic guided interventions in a saphenous vein bypass graft

Chromatic distortion during angioscopy: assessment and correction by quantitative colorimetric angioscopic analysis

Angioscopy represents a diagnostic tool with the unique ability of assessing the true color of intravascular structures. Current angioscopic interpretation is entirely subjective, however, and the visual interpretation of color has been shown to be marginal at best. The quantitative colorimetric angioscopic analysis system permits the full characterization of angioscopic color using two parameters (C1 and C2), derived from a custom color coordinate system, that are independent of illuminating light intensity. Measurement variability was found to be low (coefficient of variation = 0.06-0.64%), and relatively stable colorimetric values were obtained even at the extremes of illumination power. Variability between different angioscopic catheters was good (maximum difference for C1, 0.022; for C2, 0.015). Catheter flexion did not significantly distort color transmission. Although the fiber optic illumination bundle was found to impart a slight yellow tint to objects in view (deltaC1 = 0.020, deltaC2 = 0.024, P < 0.0001) and the imaging bundle in isolation imparted a slight red tint (deltaC1 = 0.043, deltaC2 = -0.027, P < 0.0001), both of these artifacts could be corrected by proper white balancing. Finally, evaluation of regional chromatic characteristics revealed a radially symmetric and progressive blue shift in measured color when moving from the periphery to the center of an angioscopic image. An algorithm was developed that could automatically correct 93.0-94.3% of this error and provide accurate colorimetric measurements independent of spatial location within the angioscopic field. In summary, quantitative colorimetric angioscopic analysis provides objective and highly reproducible measurements of angioscopic color. This technique can correct for important chromatic distortions present in modern angioscopic systems. It can also help overcome current limitations in angioscopy research and clinical use imposed by the reliance on visual perception of color.

Coronary angioscopy. Clinical applications

Percutaneous coronary angioscopy is an invaluable alternative imaging modality that can not be used routinely in the interventional cardiac catheterization laboratory. The major value of angioscopy lies in its ability to determine safely, quickly, and accurately intraluminal morphologies before and after coronary interventions. The results from angioscopy can then be used to target more specific treatment strategies, given the vast array of interventional treatment strategies available. Percutaneous coronary angioscopy, however, requires meticulous attention for the proper preparation and use of the angioscope to minimize the potential risks associated with the imaging procedure.

Effects of surgical manipulation on coronary stents: should surgical strategy be altered?

BACKGROUND

Coronary artery bypass grafting is usually indicated for those patients who undergo open heart surgical procedures who have previously undergone percutaneous transluminal coronary angioplasty regardless of the absence of stenosis. Occasionally, however, if the treated artery has remained patent for many years and there is a shortage of conduit material or the patient is undergoing a complex operation, the branch is left ungrafted. With the gaining popularity of coronary stent placement, patients with these devices are undergoing open heart operations with increasing frequency.

METHODS

To determine whether normal surgical manipulation during open heart surgical procedures results in obliteration of the Palmaz-Schatz stents previously deployed in the epicardial arteries, we developed an experimental model using ten isolated adult pig hearts. This allowed us to perform stent deployment and surgical manipulation and to apply direct pressure on the stented areas, with each heart evaluated by angioscopy and angiography and, finally, stent explantation.

RESULTS

Retraction of the heart resulted in severe deformity of all left anterior descending artery stents, mild deformity of those in the circumflex artery, and mild or no deformity of those in the right coronary artery. However, direct pressure over the stented epicardial arteries (enough to retract the heart) resulted in complete obliteration of every intracoronary stent.

CONCLUSIONS

The findings from this study indicate that once the need for surgical revascularization arises, a previously stented coronary artery should be bypassed even if the angiographic findings are normal, because of the likelihood that manipulation during an open heart operation will result in significant deformity or obliteration of the stent.

Transcatheter aspiration of atheroma prolapsing through saphenous vein graft stents

Endoluminal stenting has often become the percutaneous treatment of choice for older vein grafts. We report a case of successful stenting of a degenerated vein graft that was complicated by prolapse of atheroma through the stents leading to ischemia that was successfully reversed by catheter aspiration of the prolapsed atheroma.

Angioscopic evaluation of atherosclerotic plaques: validation by histomorphologic analysis and association with stable and unstable coronary syndromes

OBJECTIVES

We validated coronary angioscopic observations with histologic assessment of material removed by atherectomy.

BACKGROUND

Up to now, angioscopic findings have been primarily descriptive, and the clinical significance still needs to be substantiated. The proposed Ermenoville classification is relevant but has not yet been validated by histomorphologic analysis.

METHODS

We compared angioscopic findings in patients with different coronary syndromes and used atherosclerotic material retrieved by directional coronary atherectomy to validate the angioscopic observations. Coronary angioscopy was performed in 63 patients (56 men, 7 women) with stable (26 patients) and unstable angina (37 patients) before and after directional coronary atherectomy. The identity of atherectomized material was confirmed by ex vivo visualization with the angioscope and by postatherectomy angioscopy. Angioscopic and histologic findings could be compared in 44 of 63 patients.

RESULTS

Angioscopic findings were grouped into gray-white and yellow lesions (gray-yellow, deep yellow, yellow-red or yellow-pink). We found that patients with unstable angina had predominantly yellow lesions (89%). In patients with stable angina, gray-white (43%) or yellow (57%) lesions were similarly distributed. Ruptured yellow plaques and red or pink thrombi were identified in 11% of patients with stable angina and 39% of patients with unstable or early postmyocardial infarction angina. Histologically, gray-white lesions represented fibrous plaque without degeneration in 64% and with degeneration in 36% of patients. Gray-yellow lesions were associated predominantly with degenerated plaque (64%) and, to a lesser extent, with fibrous plaque (14%) or atheroma (14%). Deep yellow and yellow-red lesions represented either atheroma (53%) or degenerated plaque (42%).

CONCLUSIONS

Our study establishes a histomorphologic basis for classification and interpretation of angioscopic findings. Yellow plaque color is closely related to degenerated plaque or atheroma and is associated with unstable coronary syndromes.

Efficacy of angioscopy in determining the effectiveness of intracoronary urokinase and TEC atherectomy thrombus removal from an occluded saphenous vein graft prior to stent implantation

Percutaneous revascularization of thrombus containing saphenous vein grafts is associated with a high incidence of acute complications. This case report describes successful revascularization of an occluded vein graft employing angioscopically guided sequential urokinase infusion, TEC atherectomy and stent implantation.