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At least 325 records · Page 18Linked to original sources
PubMed1998

Transcatheter endomyocardial laser revascularization: a feasibility test.

By means of a special catheter system, a total of 76 endomyocardial laser channels were percutaneously produced in a controllable manner at selected sites in 6 beating canine hearts. Acute patency of channels (length = 4-11 mm, diameter = 0.5-1.2 mm) was documented angioscopically and histologically. This minimally invasive method might be useful for revascularising certain patients with ischemic heart disease without resorting to open-chest surgery.

Angioscopy↗
PubMed1988

Usefulness of angioscopy in stenotic processes of the carotid--a comparison with morphological findings.

The development of a new generation of ultrathin flexible fiberscopes permitted direct in-vivo intravascular visualization of pathological changes. But not until the construction of a double-lumen balloon catheter for simultaneous obstruction of the blood flow and rinsing of the vessel did an accurate percutaneous transluminal examination become possible. For testing the usefulness of angioscopic intraluminal diagnosis, 48 carotid arteries from 32 autopsies were examined independently by angioscopy and morphologically. There was a high degree of correspondence between the two methods, especially in cases with low-degree stenosis or complicated plaques, in which other examination methods often fail. Problems of underestimating fibrous plaques and optical projection upstream of the stenosis are discussed.

Arterial Occlusive Diseases↗
PubMed1990

[The simultaneous video fluoangioscope].

The present paper describes the video simultaneous fluoangioscope. It is based on the Rodenstock simultaneous fluoangioscope, an accessory for use with the laser slit-lamp. It has been proving its clinical usefulness since 1984. Hitherto, its optical superimposition of the corresponding fluorescein angiograph onto the actual fundus view was based on angiographic film as an information carrier. Digital fluorescein angiography (videoangiography) has meanwhile made film superfluous while at the same time opening up new possibilities. The video simultaneous angioscope superimposes a selected video half-frame onto the fundus, thus transferring angiographic data and facilitating safe and easy coagulation. The advantages and new possibilities arising from them are discussed and the system peripherals are described. An illustration shows the superimposition of the images when looking through the slit-lamp.

Equipment Design↗
PubMed1986

Coronary angioscopy in patients with unstable angina pectoris.

To visualize intracoronary lesions in patients with different clinical expressions of coronary disease, we performed coronary angioscopy during coronary-artery bypass surgery in 10 patients with unstable angina and 10 patients with stable coronary disease. We examined a total of 32 vessels, using flexible fiberoptic angioscopes. Twenty-two vessels had no acute intimal lesion; three had complex plaques, six had thrombi, and one had both. Coronary angiography correctly identified the absence of complex plaque and thrombus in 22 vessels, but it detected only one of four complex plaques and one of seven thrombi. On angioscopy, none of the 17 arteries in the patients with stable coronary disease had either a complex plaque or thrombus. In the "offending" arteries of the patients with unstable angina, all three patients with accelerated angina had complex plaques and all seven with angina at rest had thrombi. We conclude that angioscopy frequently reveals complex plaques or thrombi not detected by coronary angiography. Our observations suggest that anginal syndromes that are refractory to medical treatment can be caused by unstable pathologic processes in the intima. Ulceration of plaques may increase the frequency and severity of effort angina, and the subsequent development of partially occlusive thrombi may cause unstable rest angina.

Adult↗
PubMed2000

Clinical experience with autologous endothelial cell-seeded polytetrafluoroethylene coronary artery bypass grafts.

OBJECTIVE: Autologous endothelial cell seeding was used to improve the patency of 4-mm polytetrafluoroethylene vascular prostheses. METHODS: Since 1995, 14 patients with coronary artery disease received 21 autologous endothelial cell-seeded polytetrafluoroethylene vascular bypass grafts for coronary artery revascularization. The polytetrafluoroethylene grafts were seeded with the endothelial cells in a multiple step procedure, including cell culture techniques before coronary bypass operation. With the use of extracorporal circulation and cardioplegic arrest, a bypass operation was performed by means of conventional surgical techniques. RESULTS: After a mean postoperative follow-up of 27.7 months (range, 7.5-48 months), the graft patency rate is 90.5%. Follow-up angiograms of the aorta-coronary polytetrafluoroethylene bypass grafts showed patent bypasses in all cases except two. Angiograms of all 19 patent endothelial cell-seeded polytetrafluoroethylene bypass grafts showed a smooth luminal borderline without stenotic regions. The percutaneous transluminal angioscopic evaluation showed a glossy white and smooth endoluminal graft surface without any fibrin, platelet, or erythrocyte deposits. Intravascular ultrasonographic examinations confirmed the results. CONCLUSION: Patency of autologous endothelial cell-seeded 4-mm polytetrafluoroethylene vascular prostheses as coronary artery bypass grafts was much better than that of unseeded polytetrafluoroethylene grafts. Further evaluations and a larger population of patients will prove whether the encouraging patency will last.

Aged↗
PubMed1987

Intraoperative video angioscopy compared with arteriography during peripheral vascular operations.

In a prospective study, we assessed the diagnostic and therapeutic applications of intraoperative angioscopy for peripheral vascular procedures. Sixty-seven vessels and 17 bypass grafts were examined with a flexible, multichannel, fiberoptic endoscope (outer diameter 2.8 mm), with video projection of a magnified image used during the following operations: femoropopliteal or femorotibial bypass (14), aortofemoral (six), axillopopliteal bypass (one), and femoral embolectomy (three). Preoperative angiograms were compared with the findings at prebypass intraoperative angioscopy. Immediately after bypass, angioscopic appearances of the graft, anastomosis, and distal runoff artery were compared with a completion angiogram. Significant disparity between angioscopy and arteriography occurred in five patients (21%), with resultant change of management in three (12.5%). In comparison to angioscopy, the arteriograms gave a false negative rate of 12.5% (3 of 24) and a false positive rate of 8% (2 of 24). Angioscopy was accurate for assessment of anastomoses in all cases and was particularly beneficial for monitoring balloon catheter embolectomy. Complications were limited to three instances of vasospasm when the scope was used in narrow vessels. No embolization, intimal trauma, infection, or vessel perforation occurred. We conclude that angioscopy promises to be a safe and accurate alternative technique for intraoperative assessment, monitoring anastomotic results and controlling therapeutic procedures.

Angiography↗
PubMed2003

Laparoscopic inferior vena cava and right atrial thrombectomy utilizing deep hypothermic circulatory arrest.

BACKGROUND AND PURPOSE: Surgery for renal cancer associated with a level III or IV tumor thrombus often involves cardiopulmonary bypass, deep hypothermia, and exploration of the right atrium and inferior vena cava (IVC). This major open operation necessitates a large median sternotomy incision and a midline abdominal or chevron incision. Herein, we investigate the feasibility of purely laparoscopic IVC and right atrial thrombectomy utilizing deep hypothermic circulatory arrest. MATERIALS AND METHODS: In six male calves weighing 70 to 80 kg, the right common carotid artery and right internal jugular vein were cannulated for subsequent cardiopulmonary bypass. One laparoscopic team performed right radical nephrectomy and complete mobilization of the intra-abdominal IVC by a four-port approach. Simultaneously, a second laparoscopic team obtained three-port thoracoscopic access to incise the pericardium and expose the right atrium. In sequence, cardiopulmonary bypass, complete exsanguination, cardiac arrest, and core hypothermia of 18 degrees C were achieved. A coagulum thrombus was created by needle injection into the IVC. Combined laparoscopic and thoracoscopic incision, exploration, and thrombectomy of the IVC and the right atrium were then performed in a bloodless field. An angioscope was inserted inside the heart and the IVC to confirm complete thrombus clearance visually. The IVC and right atrium were then laparoscopically suture repaired, cardiopulmonary bypass was reestablished, and the animal was gradually rewarmed. Once sinus rhythm was reestablished at normal body temperature, the animal was weaned off the pump. RESULTS: The mean total operative time was 494.5 minutes (range 355-705 minutes). The mean time needed to lower the core temperature was 63.5 minutes (range 50-120 minutes), and the mean time required to rewarm the animal was 101.8 minutes (range 70-130 minutes). The mean blood volume drained into the pump was 2633.3 mL (range 1400-3200 mL), and the mean estimated blood loss was 350 mL (range 200-750 mL). Reestablishment of sinus cardiac rhythm and weaning off the pump was successful in all animals prior to acute euthanasia. CONCLUSIONS: Laparoscopic radical nephrectomy with thrombectomy for level III or IV tumor thrombi utilizing deep hypothermic circulatory arrest is feasible in the calf model using minimally invasive techniques exclusively. The procedure is technically complex and requires the combined efforts of expert urologic and cardiac operative teams. Survival studies are planned.

Animals↗
PubMed1991

Experimental studies using laser angioplasty combined with balloon angioplasty for stenotic cerebral lesions.

Basic studies were carried out on the treatment, with argon laser and balloon dilatation catheter, of stenotic arteries resulting from atherosclerotic plaque. Seventeen rabbits approximately 34 weeks old and weighing between 3 and 4 Kg were used. Each rabbit was fed a 1% cholesterol diet for 3 to 4 months to induce atherosclerotic lesions in the carotid arteries and the aorta. The argon laser unit used was a Model 20 Endocoagulator (HMG, Inc.; maximum power, 12W). Under an angioscope, two bare-ended laser probes (1.5 mm and 0.3 mm in diameter) were used to vaporize atheromatous plaque in the aortas of 10 rabbits, and a metal tip laser probe in the case of seven rabbits. The plaque remaining after this laser angioplasty was compressed to the luminal surface through inflation of a balloon catheter (balloon angioplasty) in order to sufficiently dilate the arteries. The animals were then sacrificed and examined both macroscopically and microscopically. When the bare-ended probes were used, there was a change in the depth of vaporization in line with the direction of the laser beam. Using a laser heating power of 25 J, perforation of the vessel wall was observed in 36% of the trials. A higher frequency of perforation was seen with the 0.3 mm probe than with the 1.5 mm probe. However, a constant vaporizing effect was achieved using the metal tip laser.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Laser↗
PubMed1993

Transadventitial localisation of atheromatous plaques by fluorescence emission spectrum analysis of mono-L-aspartyl chlorin e6.

OBJECTIVE: The aim was to demonstrate specific detection of the fluorescence spectra of mono-L-aspartyl chlorin e6 (NPe6) emitted from atherosclerotic arterial lesions using an extravascular approach. METHODS: Cholesterol fed atherosclerotic rabbits were injected intravenously with 0.5 mg.kg-1 of NPe6. A fluorescence spectrum analysis system with a dual real time imaging system and a flexible endoscopic catheter was used. The pulsed excimer dye laser excited the photosensitiser. The fluorescence spectra were measured by a fluorescence spectrophotometer. RESULTS: Analysis of fluorescence spectra detected from outside the adventitia showed that a fluorescence spectrum peak at 675 nm was obtained only in parts of the artery with an atheromatous plaque; however, no fluorescence could be shown in aortic segments free of atheroma. It was also noted that the intensity of the specific peak of the spectrum detected from outside a vessel was closely related to the depth of atheromatous lesions, as determined by histological analysis. An in vivo study revealed good correlation between the peak intensity (which could vary with the amount of NPe6 accumulated in the tissue) measured laparoscopically from outside the abdominal aorta and the peak intensity measured angioscopically from inside the abdominal aorta. CONCLUSIONS: It is possible to detect atheroma from outside a vessel by fluorescence spectrum analysis employing NPe6 as the probe.

Animals↗
PubMed1991

True ablation of atheromatous plaques with laser energy. A phase I safety study.

A laser system coupling pulsed dye laser to a 2-mm fiberoptic catheter with incorporated angioscope has been developed for recanalization of occluded arteries. Nine patients with superficial femoral artery occlusions of 4.5 to 49 cm in length were operated on and the recanalized artery harvested for pathologic examination. There were two arterial perforations. The ease of recanalization was determined by plaque composition. Heavily calcified and yellow fibro-fatty lesions were rapidly removed. Smooth white fibrous lesions resisted laser ablation. Direct angioscopy often disclosed discontinuous areas of occlusion that were more susceptible to recanalization. These were not seen on preoperative arteriograms. Microscopic examination of the specimens showed a central core of ablation. There was no evidence of acute damage to the vessel wall, with intact internal elastic lamina demonstrated in the recanalized segments. It appears that fibrous lesions will require a different laser for ablation; however, the delivery/angioscope systems function satisfactorily.

Arteriosclerosis↗
PubMed1999

Angioscopy-assisted aneurysm clipping.

OBJECTIVE: To test the concept that endovascular angioscopy can assist surgical intracranial aneurysm clipping by providing an endoluminal view of the aneurysm-parent vessel complex. METHODS: A carotid bifurcation aneurysm was surgically created in a dog at the lingual artery origin. A balloon catheter was inflated proximal to the aneurysm to block proximal blood flow and allow endoluminal visualization. A flexible angioscope connected to a video monitoring system and to a high-intensity light source was then advanced within the catheter lumen and positioned immediately distal to the catheter tip. The aneurysm neck was clipped, and the clip was repositioned several times along the neck, with or without distal parent vessel compromise. Each time, the endovascular image on the monitor was interpreted by an observer blinded to the position of the clip. Clip position and image interpretation were communicated independently to a third person, who analyzed the correlation between them. RESULTS: Angioscopy allowed clear visualization of the extent of aneurysm neck occlusion (complete, incomplete, residual "dog ear") after clip application, as well as the presence or absence of distal parent vessel compromise. Aneurysm neck configuration, size, presence of thrombus, and suture line definition were depicted. Critical structures external to the aneurysm-parent vessel complex were transilluminated by the high-intensity lamp. CONCLUSION: Although acknowledged as the treatment of choice for intracranial aneurysms, surgical exclusion can be accompanied by significant morbidity related to perforator occlusion, parent artery compromise, and/or persistent residual aneurysm. The availability of a device allowing visualization of an aneurysm from an endoluminal perspective theoretically could reduce the incidence of these complications. Angioscopy has the potential to become a useful adjunct during intracranial aneurysm clipping because it provides real-time endoluminal viewing of the aneurysm-distal parent vessel complex, which is sometimes obscured to the surgeon.

Angioscopy↗
PubMed1993

Local calcification as a determinant of the outcome of excimer laser coronary angioplasty: an in vitro study.

BACKGROUND: Calcification influences the outcome of various angioplasty techniques in the treatment of coronary artery disease. During angioscopic in vitro studies, we observed that dissections and perforations not caused by vessel bending frequently occurred at the boundary areas of plaque and adjacent vessel wall. This study investigated whether this is related to the distribution of calcific deposits. METHODS: Postmortem excimer laser coronary angioplasty (308-nm XeCl) was performed in 51 stenotic coronary arteries. Twenty-three segments were further examined; these consisted of 11 perforations, six dissections, three segments with no ablative effect after the application of 20,000 laser impulses, and three successfully passed stenoses without complications. X-ray diffraction analysis and scanning electron microscopy were performed to detect calcium deposits and their spatial relationship to perforations and dissections. RESULTS: X-ray diffractions analysis detected calcifications in 21 of 23 specimens. Postmortem angiography revealed calcifications only on 11 of 23 segments. Three of 11 perforations were located at the plaque border, as were three of six dissections. In all six complications at the plaque border, x-ray diffraction analysis revealed that the plaque border was identical with a border of calcium deposits. Eight of 11 perforations and three of six dissections could be explained by axis divergence between the laser catheter and the vessel orientation. CONCLUSIONS: Contributing factors for perforations and dissections during excimer laser coronary angioplasty are axis divergence and the distribution of plaque calcification. More sensitive methods are needed to detect local vessel wall calcium in vivo.

Angioplasty, Balloon, Coronary↗
PubMed2006

Stent-based delivery of antisense oligodeoxynucleotides targeted to the PDGF A-chain decreases in-stent restenosis of the coronary artery.

BACKGROUND: Although the use of drug-eluting stents (DESs) has been shown to limit neointima hyperplasia, currently available DESs may adversely affect reendothelialization, possibly precipitating cardiac events. We evaluated the effect of an antisense oligodeoxynucleotide (ODN) targeted to the platelet-derived growth factor (PDGF) A-chain on in-stent restenosis in pig coronary artery. METHODS: A bare metal stent coated with phosphorothioate-linked antisense ODN or nonsense ODN, or a bare metal stent without ODN (control), was implanted in the mid segment of the left anterior descending artery (LAD). Twenty-eight days after implantation, angiography and intravascular ultrasound (IVUS) were performed, the LAD was removed, and stenosis was evaluated pathologically. RESULTS: Volumetric stenosis ratios were 64 +/- 11.9, 44 +/- 3.4, and 26 +/- 3.8% in coronary arteries implanted with control, nonsense ODN-coated, and antisense ODN-coated stents, respectively. In angioscopic findings, the lumen surface was smooth in the stented segments in all groups. Struts of antisense ODN-coated stents were observed embedded in the neointima, whereas embedding was not observed in nonsense ODN-coated stents or control stents, indicating a decrease in hyperplasia in response to antisense ODN treatment. Pathologic findings showed 77 +/- 5.8, 68 +/- 12.2, and 38 +/- 5.3% stenosis in coronary arteries implanted with control stents, nonsense ODN-coated stents, and antisense ODN-coated stents, respectively. A continuous lining of endothelial cells was observed along the lumen of coronary arteries implanted with antisense ODN-coated stents. CONCLUSIONS: Stent-based delivery of an antisense ODN targeted to the PDGF A-chain effectively inhibits neointima formation after stent implantation in pig coronary artery by suppressing VSMC hyperplasia and preserving endothelialization. Antisense-ODNs may provide a therapy for in-stent restenosis of the coronary artery.

Animals↗
PubMed2004

Depth-map-based scene analysis for active navigation in virtual angioscopy.

This paper presents a new approach dealing with virtual exploratory navigation inside vascular structures. It is based on the notion of active vision in which only visual perception drives the motion of the virtual angioscope. The proposed fly-through approach does not require a premodeling of the volume dataset or an interactive control of the virtual sensor during the fly-through. Active navigation combines the on-line computation of the scene view and its analysis, to automatically define the three-dimensional sensor path. The navigation environment and the camera-like model are first sketched. The basic stages of the active navigation framework are then described: the virtual image computation (based on ray casting), the scene analysis process (using depth map), the navigation strategy, and the virtual path estimation. Experimental results obtained from phantom model and patient computed tomography data are finally reported.

Algorithms↗
PubMed1995

Future challenges to coronary angioplasty: perspectives on intracoronary imaging and physiology.

Several intravascular techniques have been developed with the purpose of achieving optimal guidance for treatment during coronary angioplasty (PTCA). Although the coronary angiographic technique is well established, there are still some inherent limitations. Due to intimal rupture, tears, dissection and thrombus following PTCA treatment, angiography does not allow exact delineation of the true borders of the vessel. Coronary angioscopy is currently the most sensitive method to detect coronary thrombus and can also be used to classify atheromatous plaques. Furthermore, coronary dissection can be detected with more accuracy than with angiography. One limitation associated with angioscopy is the need to occlude the vessel during imaging, which may create myocardial ischaemia. Furthermore, there is presently no method for quantifying angioscopic findings. Intravascular ultrasound produces a cross-sectional image of the vessel, which permits analysis of the layers of the vascular wall. Characterization and classification of various types of plaque can be made because thrombus, lipid, fibrous tissue and calcium have different ultrasonic echogenicity. Flow velocity measurement with the Doppler technique is an interesting approach to the physiological assessment of coronary stenoses. Coronary flow reserve can be estimated with this method and monitoring of the flow signal following angioplasty will aid in the diagnosis of flow-limiting complications. The trans-stenotic pressure gradient is a valuable measure of the haemodynamic importance of a coronary lesion. Trans-stenotic gradients during maximal hyperaemia obtained with a miniaturized pressure transducer yield reliable information regarding the severity of the stenosis, and the pressure values may be used to calculate the relative coronary flow reserve. In conclusion, all of these intracoronary diagnostic techniques will to some extent play a role in the future of coronary angioplasty. Safety, cost and complexity are some of the factors which will determine the growth potential of each method.

Angioplasty, Balloon, Coronary↗
PubMed1988

In situ saphenous vein bypass: prevention and management of early complications.

Since adopting the in situ, non-reversed saphenous vein technique for bypass procedures in the leg early in 1986, 50 bypasses have been performed in selected patients, primarily for limb salvage. A Mills valvulotome was used for retrograde disruption of the saphenous valves, after exposure of the whole length of vein. Significant peri-operative complications occurred in nine patients and were strongly associated with technical factors. Early graft occlusion (n = 2) and residual arteriovenous fistulae (n = 2) were revised by timely reoperation, resulting in early (30 day) patency of all but one graft. In seven patients, angioscopic visualization of the valve division process was tested as a method of ensuring complete valvulotomy, while avoiding trauma to the vein wall. Distal anastomosis to the popliteal artery above the knee or close below the knee caused a considerable degree of graft angulation, which was exacerbated by flexion of the leg, whereas anastomosis to the more distal popliteal artery or tibial vessels resulted in a favourable curvature of the graft. Lessons learned during this initial experience and aspects of technique for prevention of complications are presented.

Aged↗
PubMed1992

Percutaneous angioplasty of chronic obstruction of peripheral arteries by a temperature-controlled Nd:YAG laser system.

The feasibility of an Nd:YAG laser system with automatic control of hot-tip probe temperature was examined in 15 segments (14.7 +/- 6 cm in length) of iliofemoral arteries from 13 patients. The hot-tip temperature to be attained and the upper limit temperature at which lasing was to be stopped were preset. A catheter with a 1.8-mm hot-tip probe was introduced into the obstructed segment and angioplasty (lasing time 5-10 sec) was performed under angioscopic guidance. Recanalization was observed in all segments without obvious complications. No thermal effects below 50 degrees C, coagulation at 100 degrees C, carbonization at 200 degrees C, or sticking of the hot-tip to the luminal surface at 300 degrees C or over, were observed by angioscopy. Rapid recanalization was obtained between 200 degrees C and 300 degrees C. The results indicate that this novel laser system is feasible and hot-tip temperature between 200 degrees C and 300 degrees C is ideal for treatment of chronic arterial obstruction in Japanese patients.

Aged↗
PubMed1994

Percutaneous angioscopy in patients with restenosis after excimer laser coronary angioplasty.

Coronary angioscopy was performed in two patients with restenosis after excimer laser coronary angioplasty to improve our knowledge of restenosis after excimer laser angioplasty. The characteristics of the angioscopic findings in restenosis after excimer laser angioplasty consisted of smooth white plaques, which were distinctly different from the yellow plaques commonly observed in primary lesions. These findings indicate that restenosis in these patients after excimer laser angioplasty may be associated with smooth muscle cell proliferation and fibrosis.

Angioplasty, Laser↗