Intracoronary stenting after unsuccessful PTCA. Early restenosis and explanation of stents during bypass surgery.

The case of a 63-year-old man is described, who received two intracoronary Palmaz-Schatz-Stents after dissection and occlusion following PTCA of two segments of the left anterior descending branch of the left coronary artery. Because of recurrent angina caused by early restenosis in the 'unprotected' segment between the stents, surgical revascularisation was performed and the stents were removed.

Comparative analysis of glutaraldehyde-preserved porcine xenografts and fresh or glutaraldehyde-treated human aortic valves by holographic interferometry.

Although calcification and degeneration are recognized as the main causes of bioprosthetic heart valve failure, the reasons for such failure are not well understood. Hidden tissue anomalies in the valves may be the origin of later calcification. Application of hologram interferometry for non-destructive testing enables the detection of such tissue anomalies. A comparative study by holographic interferometry of ten porcine bioprosthetic valves (seven Carpentier-Edwards SAV, two BioImplant and one Valcor) with five human aortic valves before and after glutaraldehyde treatment is presented. Whereas irregularities were detected in the interferograms of eight out of ten bioprostheses, no similar distorted fringe pattern was found in the holographic interferograms of human specimens. The present results suggest that tissue abnormalities exist in standard bioprosthetic valves which are absent in human ones. These irregularities may be the origin of later calcification and valvular dysfunction.

Holographic interferometry: a new technique for in vitro investigations of prosthetic heart valves.

At present there are many different prosthetic models available for heart valve replacement. Postimplant dysfunction resulting from material failure has been reported in several prostheses. The prime cause of these defects is hidden abnormalities in the valve construction or materials. In order to detect these defects before implantation, preoperative non-destructive testing of individual valves is proposed. For this purpose, holographic interferometry has been applied which is a non-contact, non-destructive, highly sensitive, three-dimensional measurement technique. Samples of different types of prosthetic heart valve, both mechanical and biological, were mounted in a specially developed test chamber with optical access from four sides. The valves were loaded with a static liquid pressure of 2.5-15 kPa. Deformations of the valves as a result of small pressure differences (0.5-15% of the static pressure) applied between two exposures were recorded by double-exposure holography. A fringe pattern superimposed on the image of the valve reconstructed from the hologram clearly indicates the presence of defects in the valve material.

Non-destructive evaluation techniques for prosthetic heart valves based on hologram interferometry. Part I.

The development of a technique applying hologram interferometry, which is a non-destructive, non-contact, full-field, highly sensitive method is reported. The valve under investigation is placed in a test chamber which has windows providing optical access. Deformations of the valve leaflets due to pressure loading are recorded by hologram interferometry. The resulting interferogram clearly indicates the existence of any defects or structural anomalies which may be present in the valve material. Three modifications to this technique, intended for qualitative and quantitative non-destructive valve screening tests are described. The proposed technique is expected to become an effective means of detecting hidden defects of replacement heart valves; it is thus considered as a prospective tool for quality control, particularly in the manufacture of bioprosthetic valves, where initial sites of late calcification and degeneration might be identified. The application of holographic non-destructive testing may therefore substantially improve the quality and durability of heart valve substitutes.

Non-destructive evaluation techniques for prosthetic heart valves based on hologram interferometry. Part II: Experimental results and clinical implications.

Non-destructive evaluation by hologram interferometry of seven mechanical and seven bioprosthetic valves was carried out. Irregular fringe patterns suspect of intrinsic valve anomaly which may lead to later dysfunction were detected in one mechanical and six bioprosthetic valves. Histologic examination of two bioprosthetic valves revealed focal degeneration, especially in the fibrosa, in those parts of the leaflets that had obvious anomalies on the holographic interferograms. It was shown that the flow turbulences caused by prosthetic valves can also be evaluated using hologram interferometry. The experimental results, obtained with six different types of prostheses (Lillehei-Kaster, Bjork-Shiley, Omnicarbon, St. Jude Medical, Carpentier-Edwards S.A.V. and Valcor), demonstrated the applicability of this technique to both mechanical and bioprosthetic valves. Carrying out non-destructive screening tests for heart valve prostheses may prevent the implantation of potentially dysfunctional devices.

Non-destructive evaluation of prosthetic heart valves by holographic interferometry.

Dysfunction of prosthetic heart valves is a common complication after heart valve replacement, affecting both biologic and mechanical prostheses. A preoperative, non-destructive test of each individual valve may help to prevent the implantation of a valve which has material weaknesses. To this end we developed a technique for testing heart valve prostheses by holographic interferometry. The advantage of this technique is that it provides a non-contact, non-destructive, highly sensitive three dimensional analysis of the valve under loading. Samples of several mechanical and biologic valve substitutes were investigated. Deformations of the valve, due to small pressure differences applied to the samples in a specially developed test chamber, were recorded by double exposure holography. A fringe pattern superimposed on the image of the valve reconstructed from the hologram clearly indicates the presence of even the slightest defect in the valve material. Our experimental results demonstrate the ability of non-destructive holographic screening testing to detect defects or weaknesses which may potentially lead to dysfunction in replacement valves.

Thoracoscopic treatment of recurrent pneumothorax by pleurabrushing and argon beam coagulation.

There is no consensus in treating relapsing pneumothorax and pleural effusion. Various types of treatment exist. While open chest surgery with mechanical pleurodesis or pleurectomy is effective, with a recurrence rate close to zero, for patients in poor conditions this treatment may be disadvantageous because of its invasiveness. Therefore minimally invasive techniques using antibiotics, fibrin glue, talcum, kaolin, blood and silver nitrate have been described. Several side effects accompany these agents, and the recurrence rate is between 5-39%. New video-assisted thoracoscopic techniques have enabled surgeons to combine the effectiveness of pleurectomy with minimal invasiveness. Results using these techniques are encouraging. As with open pleurectomy, bleeding complications have been reported, Further disadvantages have to be considered, such as the effect of destroying the parietal layer of the pleura, which may complicate subsequent operations in the thoracic cavity. A technique for avoiding this pleural injury, while maintaining the same efficiency as open pleural abrasion and coagulation is described below.

Echinococcal cyst of the interventricular septum: a rare cause of myocardial ischemia.

A 30-year-old woman developed ischemia-like chest pain due to myocardial compression by an intracardiac cyst. The cyst was located in the interventricular septum. Its etiology could not be ascertained despite several diagnostic measures but exstirpation was indicated by the clinical symptoms. Intraoperatively the diagnosis of echinococcosis was established. The cyst was extirpated in toto without perforation of the thinned interventricular septum. Postoperatively the patient was symptomfree.