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PubMed2000

[Evaluation of in vitro human blood transparentized using near-infrared light].

We developed a new technique for the in vitro imaging of transparent human blood and examined the resolution of a test chart in transparent blood. We utilized mainly three devices: a laser diode (wavelength 833 nm) that served as the light source, a near-infrared camera, and a fiberscope adapted for the camera. Blood was collected from a human femoral artery. We observed the images of transparent blood and the fiberscope image of a target in the blood using the light. These results indicate that further improvements in this system can be expected and real-time viewing by angioscope may be realized in vivo.

Blood↗
PubMed1997

Thermal Effects In Vivo from Holmium: YAG Lasing in the Intracoronary Setting.

While the thermal effect of laser energy does ablate atheromatous plaque, thermal injury to adjacent tissue produces high rates of arterial thrombosis and spasm. Holmium:YAG lasers use a pulsed laser source to maximize photoblative effects while minimizing thermal effects. These lasers have been utilized clinically to ablate thousands of complex coronary lesions with low rates of spasm and thrombosis, suggesting that little or no thermal injury occurs with these devices. However, we have been able to detect thermal injury in patients angioscopically in coronary arteries after holmium:YAG lasing. Here we report the use of directional coronary atherectomy (DCA) to ÒbiopsyÓ arteries in patients following holmium:YAG laser treatment, allowing direct histologic examination of lased tissue. Thirty such lased DCA samples were matched for patient age, gender, target vessel, and lesion characteristics with thirty control DCA samples obtained from patients undergoing DCA without prior lasing. Blinded pathologic examination correctly identified 27/30 control samples but only 18/30 lased samples. Subsequent unblinded analysis, sometimes with recutting and restaining of tissue blocks, resulted in the detection of thermal effects in 27/30 lased samples. The thermal effects seen included edge disruption, charring, coagulation necrosis, and most commonly, vacuolization. We conclude that holmium:YAG lasing does produce detectable thermal effects in tissue in most patients. These effects can be quite subtle or can be extensive, but do not predict poor patient outcome.

Journal Article↗
PubMed2001

Infrainguinal arterial reconstruction with autologous vein grafts: are the results for the in situ technique better than those of non-reversed bypass? A long-term follow-up study.

BACKGROUND: The aim of this study was to answer the question if the in situ technique in infrainguinal arterial reconstruction is better than the non reversed one in long-term follow-up. METHODS: Patients were included in a prospective study at operation. 387 infrainguinal arterial reconstructions in 367 patients performed from 10-88 to 12-98 were retrospectively analysed. RESULTS: 280 non-reversed and 107 in situ bypass procedures were performed. Primary patency rates at 60 months were 63.3% for non-reversed and 57.9% for in situ grafts (p=n.s.). Primary assisted patency rates were 81.8% and 84.5% respectively (p=n.s.). Limb salvage rate was not different in either group. The 30-day mortality was 1.9% in the in situ group and 0.7% in the non-reversed group (p=n.s.). CONCLUSIONS: There is no difference in outcome between in situ and non-reversed vein grafting. Absence of statistical difference between the two procedures may be mainly due to the routine use of angioscopic quality control.

Aged↗
PubMed2000

Concepts in acute coronary syndromes.

Landmark pathological studies have deepened our understanding of the mechanisms behind acute coronary syndromes over the last decade. Thrombosis plays a key role and is a unifying feature in the pathogenesis. Platelet-rich thrombus superimposed over the disrupted atherosclerotic plaque or eroded plaque endothelium, with or without fibrin-thrombus extension, is evident in postmortem necropsy, angiographic and angioscopic studies. However features which contribute to the risk of acute events lie in the atherosclerotic plaque itself. Plaque content and not plaque size is the important factor. A vulnerable plaque may be invisible on clinical stress testing and even coronary angiography; but it is prone to rupture if it has only a thin cap and a proportionally larger lipid core. There is a cellular preponderance of activated macrophages and T-lymphocytes; and high activity of matrix metalloproteinases in vulnerable plaques. Smooth muscle cell proliferation and collagen synthesis are downregulated. These features may serve as possible targets for detecting plaques at risk or for reversing the risk of vulnerable plaques.

Acute Disease↗
PubMed2000

[Treatment of critical lower limb ischemia--where are we standing at the turn of the Millennium?].

The treatment of chronic critical limb ischaemia (CLI) is a very important and constantly developing field of vascular surgery. The high incidence of CLI (50-100/100,000 inhabitants [10]) means that vascular surgeons at a district general hospital/county hospital, providing care for 250-300,000 people, see about 120-150 cases in a year, 70-75% of them needing elective or acute intervention. We have witnessed many important changes over the last 1-2 decades in the management of this substantial field of vascular surgery. The in situ technique, angioscopically assisted valvulotomy, venous cuffs and A-V fistulae at the distal anastomosis of an infrainguinal bypass, the intraluminal and subintimal angioplasty-technique in hand, graft-surveillance programmes and the more aggressive treatment of graft-infection all provide a potentially better chance for limb salvage. Do we follow the trends and seize them?

Acute Disease↗
PubMed2001

Present-day investigations cannot adequately determine the risk of acute coronary syndromes.

It is an important irony that present-day clinical stress testing methods including exercise electrocardiogram, stress echocardiography and even coronary angiography are not able to demonstrate vulnerable coronary plaques at risk of rupture. A vulnerable plaque may in fact be invisible on clinical stress test and perhaps only visualized directly through less available techniques such as coronary angioscopy. Landmark pathological studies have deepened our understanding of the mechanisms behind acute coronary syndromes over the last decade. Thrombosis plays a key role and is a unifying feature in the pathogenesis. Platelet-rich thrombus superimposed over the disrupted atherosclerotic plaque or eroded plaque endothelium, with or without fibrin-thrombus extension, is evident in post-mortem necropsy and angioscopic studies. However features which contribute to the risk of acute events lie in the atherosclerotic plaque itself. Plaque content and not plaque size is the important factor. Clinical stress testing demonstrates plaque size but not plaque content. A plaque will be prone to rupture if it has only a thin cap and a proportionally larger lipid core. In such a plaque there is preponderance of activated macrophages and T-lymphocytes, and high activity of matrix metalloproteinases. Smooth muscle cell proliferation and collagen synthesis are downregulated. These features may serve as possible targets for devising clinical methods to detect plaques at risk or for reversing the risk in vulnerable plaques.

Arteriosclerosis↗
PubMed1992

[Present views on unstable forms of ischemic coronary disease].

The term unstable angina pectoris covers several forms of ischemic heart disease with heterogeneous pathophysiology, different clinical presentation and non-uniform prognosis. Recent results of angiographic, angioscopic and autoptic observations on the nature of unstable coronary plaque rendered possible a better understanding of clinical symptoms of the unstable myocardial ischemia. Holter ECG monitoring of patients with unstable angina pectoris showed, that myocardial ischemia may persist despite the medical control of angina pectoris. It seems therefore more appropriate to use the terms unstable myocardial ischemia or unstable coronary syndromes rather than unstable angina pectoris. Coronary angiography in patients with unstable angina pectoris demonstrated eccentric narrowing with irregular or overhanging edges or intraluminal filling defects in 71-73% of vessels responsible for unstable myocardial ischemia. Autoptic studies showed, that thrombus usually develops on plaque with fissures, ulcerations and hemorrhage. The common pathway for all unstable coronary syndromes is an impairment of plaque integrity with subsequent activation of platelets, development of thrombosis and coronary spasm. Subsequent fate of coronary thrombus determines the clinical course with ischemic episodes lasting from several minutes to several hours. Medical therapy, PTCA or coronary bypass surgery are used to stabilise the patient, however, myocardial infarction or sudden death may occur.

Angina, Unstable↗
PubMed1992

[Angioscopy in peripheral vascular surgery].

At Saint-Luc's Hospital of Montreal, between January 1, 1990 and February 1, 1991, 47 angioscopic procedures were done in 43 patients submitted to peripheral vascular reconstructions. The purpose of the study was to evaluate the role of angioscopy during those procedures. The operations were as follows: twenty femoropopliteal bypasses done with reversed saphenous vein, 15 done with in situ saphenous veins and 10 done with synthetic grafts. Two patients had popliteal embolectomies. Seventeen percent of the cases showed technical problems with the use of controlled angioscopy and were subsequently corrected. Three residual valves and one unsuspected venous stenosis were found in 15 in situ grafts, for a total of 27% correctible defects. In the reversed saphenous group, one case of venous sclerosis and one case of anastomotic stenosis were found for a total of 10%. For the synthetic grafts group we found an intimal flap distal to the anastomosis in one case (10%). Finally, we found a significant residual clot in one case (50%) after embolectomy. The technique of angioscopy is simple, the equipment reliable, and the learning period is short. Angioscopy is a very useful approach and should be readily available in the armamentarium of every vascular surgeon.

Adult↗
PubMed1992

[Vascular endoprosthesis. A new indication in the surgery of the iliac artery].

We have used endoprosthesis (Palmaz Schatz) after balloon angioplasty of iliac arterial stenoses or thromboses, in order to increase the immediate patency and to prevent the recurrence of stenosis. Our series gathers 24 patients operated with endovascular procedures over a period of 2 years: 22 men, 2 women--extreme ages 42 to 78 years, average age 63.5 years--Clinical stage: 22 at stage I, 1 at stage III, 1 at stage IV. Arteriographic findings: 8 primary iliac lesions (6 stenoses and 2 thromboses), 11 external iliac lesions (stenoses). All these lesions were atheromatous. One of them had recurred after angioplasty. Usual technique: balloon angioplasty of the stenosis, assessment on a fluoroscopic screen and angioscopy of the result, decision to insert the Palmaz Stent if defects are seen on the image. Repatency of impassable lesions with a YAG laser was carried out in 2 cases. The indication of an endoprosthesis was established on the basis of the radiological image in 17 cases, of the angioscopic image in 4 and systematically in 10 cases of recurrence of stenosis, iliac thrombosis or associated surgery. Associated surgery: 2 femoropopiteal bypass grafts, 3 femorofemoral bypass grafts, 1 deep plasty, 1 superficial femoral recanalization with laser, 1 lymbar sympathectomy. Postoperative results: 1 death due to MI (78-year-old diabetic woman), 1 thrombosis treated with femorofemoral bypass. Middle-term results: after 6 to 24 months, average time lapse 13 months. The comparison of the ankle pressure indices and of the pre- and postoperative sonographic findings shows an indisputable hemodynamic improvement.

Adult↗
PubMed1992

Endovascular infrainguinal in situ saphenous vein bypass: a multicenter preliminary report.

The ideal operative approach for infrainguinal in situ bypass grafting would render the saphenous vein (SV) valves incompetent while occluding venous tributaries from within the SV: an endovascular in situ SV bypass. Forty-six femoropopliteal-tibial in situ bypasses were performed in part by the endovascular occlusion technique. Valvulotomy was accomplished with a retrograde "cutter" valvulotome, and endoluminal cannulation of 84 SV tributaries was performed with a shape memory metal alloy (nickle-titanium), electronically steerable catheter under angioscopic surveillance. Sixty-nine SV tributaries (82%) were totally occluded and 15 (18%) were partially occluded with platinum occlusion coils. Twelve coils that "recoiled" into the SV lumen were retrieved uneventfully. The valvulotomes caused six SV perforations that were repaired without consequence. Intraoperative fluoroscopy confirmed coil placement and verified venous tributary occlusion, as well as SV graft patency. During short-term follow-up (mean 9.2 months; range 1 to 15 months), all patients have undergone ultrasonography of the in situ bypasses. All 69 of the SV tributaries that occluded initially have remained occluded and 84% (39/46) of the in situ bypasses have remained patent. This study demonstrates that an electronically steerable nitinol catheter can be used safely to occlude venous tributaries from within the SV. Endovascular occlusion of SV tributaries may ultimately obviate the need for long incisions the length of the leg, thus reducing wound-related problems and shortening recuperation.

Aged↗
PubMed1992

[An experimental study of excimer laser angioplasty].

An excimer laser, which is a pulsed ultraviolet laser and ablates tissue precisely with no thermal injury, is expected to coronary laser angioplasty. We transmitted XeCl excimer laser (308 nm) via a 400 microns fused silica fiber. In the first experiment, we studied about excimer laser ablative effects to normal canine arteries and atherosclerotic rabbit aortas, and about healing responses following excimer laser irradiation in both models. Surfaces after excimer laser ablation were slightly rough but no thermal injury was found in the media. And for healing process of normal canine arteries, endothelial cells appeared at 3 weeks and completely covered surfaces with fibrointimal ingrowth at 3 months. In the rabbit aortas, at 3 weeks there was reconstruction of the surface. At 2 months no accelerated atherosclerotic or aneurysmal changes were observed. In the second, with this excimer laser (short pulse) and 400 microns fused silica fibers (distal fiber-end power: 3-6 mJ/pulse), we performed transluminal laser angioplasty to recanalize totally occluded canine femoral arteries under an angioscopic guidance. We cold recanalize 8 of 9 totally occluded arteries with no thermal injury of adjacent tissue, though perforations were observed in 7 of 9 arteries. In the third, we used a newly-developed long pulse excimer laser, with which distal fiber-end energy was about 3 to 4 times as much as the short pulse one, to recanalize totally occluded canine arteries. In result, recanalization was performed in 6 of 8 arteries rapidly with little thermal injury. However, we observed perforations in 6 of 8 arteries like the short pulse one. Multifiber catheter ("over the wire system") coupled with this long-pulse excimer laser was used to reconstruct stenotic iliac arteries of atherosclerotic rabbit models. The procedure was successful in all the 5 rabbits. In conclusion, our preliminary results suggested that further developments of a more powerful and longer pulse-duration excimer laser, optic delivery system and guidance system would make excimer laser angioplasty safer and more effective method in the near future.

Angioplasty, Laser↗
PubMed1992

Recanalization of chronically occluded coronary arteries.

A chronic coronary occlusion consists of an atherosclerotic plaque and one or several thrombi. It clinically imitates a tight stenosis but is exempt from the risk of truly unstable angina or myocardial infarction. Hence, quality of life is at stake and not longevity. This holds true for balloon angioplasty as well as for surgery. Indications for angioplasty are based on an estimate of technical difficulties and clinical risks balanced against potential subjective benefit and amount of viable myocardium concerned. An occlusion flush at the orifice of the vessel, tapering into a small sidebranch, with bridging collaterals, or devoid of collaterals is no target for angioplasty. Primary success is around 65% and complications are extremely rare. Abrupt vessel closure is common but harmless. No Q-wave infarctions have been reported in that context. The need for emergency bypass surgery may arise from acute closure of a vessel proximal to the occlusion in an exceptional case. Duration and length of occlusion are the most important predictors of success. Recurrence averages 62% (17% reocclusion and 45% restenosis). An important factor for the high recurrence rate is the competitive pressure exerted by the collaterals on standby. Recurrence happens almost exclusively within the first six months. It is innocuous but produces symptoms prompting further interventions (repeat angioplasty or bypass surgery). The conventional technique uses a stiff guidewire and advances the balloon catheter close to the tip of the guidewire for additional rigidity. New technologies are under investigation but no breakthrough has happened so far. They encompass blunt mechanical instruments (e.g., Magnum wire), drills of various velocities, laser energy applied directly to the tissue (some angioscopically guided, some triggered by on-line spectral tissue analysis), catheters dispersing laser energy through a sapphire or converting it into heat (hot tip), and electrical or radiofrequency heat applicators. As low-yield procedures had better be low-risk and low-cost, there are definite limits to how sophisticated, complicated, risky, and expensive tools and techniques for percutaneous coronary recanalization can become. Close relatives of conventional gear such as the Magnum system offer themselves as first choice equipment complemented, in case of need, by mechanical drills.

Angioplasty, Balloon, Coronary↗
PubMed1992

[Angioscopy of the pulmonary arteries].

The endoscopic investigation of the pulmonary arteries was developed during the 1980's. Current angioscopic techniques, which are still very limited in availability, enable an accurate endoluminal view and allow for a direct approach to endovascular obstruction. The authors describe the technique of angioscopy of the pulmonary arteries and also its indications.

Arteries↗
PubMed1997

Carbon dioxide angioscopy.

Endovascular intervention has become an increasingly more popular method of diagnosing and treating vascular disease. Its expanding scope includes applications ranging from visualization of the peripheral vascular system to coronary artery interventions. This trend is primarily a result of the limitations of angiography, the current imaging standard, when compared to angioscopy. Multiple disease entities, including atherosclerotic plaque, embolic debris, and thrombus, can not be differentiated between based on angiographic appearance. Angioscopy is a more sensitive method of distinguishing between the above disease states by allowing direct visualization of the luminal surface. The significance of this distinction lies in the fact that the treatment options are notably different based upon the diagnosis. Yet another advantage of angioscopy is its therapeutic value in addition to its diagnostic abilities. Directed embolectomy, guide-wire or catheter placement, or pseudointimal resection are all possible through the angioscope at the time of diagnosis.

Journal Article↗
PubMed1992

Intraoperative angiography and endovascular ultrasound imaging.

Endovascular ultrasound imaging is a new technique that can be used to monitor intraoperatively the effects of balloon angioplasty or to inspect the quality of vascular reconstruction, such as endarterectomy or bypass surgery. The technique is based on high frequency ultrasonic imaging (30-40 MHz) using a rotating single element transducer mounted in an 8F catheter tip, providing 360 degrees cross-sectional real time images. The clinical application is based on the high correlation between the ultrasonic images and the histological characteristics of the corresponding vessel wall tissue and lumen geometry, as has been established in previous in vitro studies. Endovascular ultrasound assessment of percutaneous angioplasty procedures or intraoperative vascular reconstruction has become an adjunct to angiographic and/or angioscopic monitoring.

Angiography↗
PubMed1991

[Thrombolysis in unstable angina].

Anatomical, coronary angiographic and angioscopic observations have revealed the frequent presence of a thrombus in the lumen of the artery responsible for ischemia in patients suffering from labile angina. A thrombus is more frequently found if coronary angiography is carried out within a few hours of angina-type pain, and its presence is a factor predicting complications (infarction, sudden death, necessity for revascularization). These observations constitute the basis of clinical trials of thrombolytic agents administered by intracoronary or intravenous route. The thrombolytic treatment does not reduce the incidence of the angina attacks (defined clinically or electrically), nor that of infarction; it produces little or no reduction (15%) in the degree of stenosis. Although lysis of the thrombus is achieved in most cases and is accompanied by immediate clinical improvement, it does not forecast the outcome in the following days. Clinical deterioration may occur, even when thrombolysis has been effective and accompanied by an improvement in the angiographic images.

Angina, Unstable↗
PubMed1991

Angioscopy.

Improved technology has made the technique of video angioscopy available. This technique, when routinely applied, can provide a wealth of important information to the vascular surgeon. The long term benefits will include improvement of surgical techniques and the potential to simplify and lower the cost of vascular surgery. The angioscope has emerged as a potentially powerful tool for today's vascular surgical team. Nurses need to be aware of this procedure so that they can provide quality care for these patients.

Blood Vessels↗
PubMedDate not supplied

Angioscopy.

Over the past three to four decades vascular surgery has experienced increasing interest and rapid growth. This surgical specialty continues to show an annual increase in the number of procedures performed, and demonstrates increasing use of innovative technology. The author explains how the angioscope has emerged as a potentially powerful diagnostic tool for today's vascular surgeon. Its implications, complications and the post operative nursing care for the patient undergoing angioscopy will be discussed.

Angiography↗