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Experimental treatment of thrombotic vascular occlusion.

The role of laser energy in the treatment of thrombotic vascular occlusion was evaluated in two sets of experiments. First, 10 polytetrafluoroethylene grafts were used to replace segments of the superficial femoral arteries in dogs and were thrombosed by distal ligation. Occlusion was maintained for one hour, or for 7, 14, 21, and 28 days in each of two grafts. Patency was restored in all 10 grafts without perforation or anastomotic disruption using a 2 mm hot tip probe powered by an Argon laser. However, increased organization of thrombus related to the duration of occlusion lead to decreased laser channel diameters, and 75% of the 28 day thrombus remained in the graft after recanalization. The second experiments tested the added benefit of thrombolytic infusion following laser recanalization. Bilateral external iliac artery thrombosis was induced in dogs by operative vessel isolation, de-endothelialization, and thrombin injection. At 7 days the efficacy of laser-assisted thrombolysis (LAT) versus enzymatic thrombolysis (ET) alone was compared. Eight vessels underwent ET by urokinase (4000 I.U./min.); 14 vessels were laser recanalized prior to thrombolytic infusion. LAT was performed from a carotid artery approach in 8 vessels (antegrade) and from a femoral artery in 6 vessels (retrograde). In contrast to studies using the hot tip alone, both ET and LAT accomplished complete thrombus removal. However, LAT lead to significant iliac arterial flow in 9 +/- 8 min. (antegrade) and 25 +/- 8 min. (retrograde) while ET required 109 +/- 47 min (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Nd:YAG laser treatment of colorectal malignancies: an experience of 4 1/2 years.

Between 1985 and 1990, 517 patients were treated for colorectal malignancies at our department of surgery. Nd:YAG laser therapy was used in 37 cases (7.1%). The mean age of these 22 men and 15 women was 71.4 years (range: 22-96 years). One hundred-twenty-nine Nd:YAG laser treatments were performed. Indications for laser treatment were (1) palliative tumor reduction (n = 21), (2) preresectional laser recanalization for obstructing carcinoma (n = 6), and (3) curative treatment (n = 10). Laser related complications included one perforation of the rectum and one rectovaginal fistula. One fatal pulmonary embolism occurred. After palliative treatment, five patients died because of tumor progression (mean survival time: 16 months), two because of other reasons. All patients with obstructing tumors could be recanalized successfully. After curative treatment, eight patients are still alive without tumor recurrence (mean survival time: 25.5 months), and two died of other causes. Palliative Nd:YAG laser treatment of colorectal malignancies is a competitive alternative to conventional surgery. Recanalization of obstructing tumors is an excellent treatment for large bowel obstruction, making one-stage resections possible. Curative treatment should be reserved for special cases only.

Adenocarcinoma↗

Current role of laser and photodynamic therapy in gastrointestinal tumors and analysis of a 10-year experience.

Laser energy can be used for a variety of neoplastic diseases including benign tumors, early stage malignancies, and advanced carcinomas, either with curative intent or for palliation. Nd:YAG laser photocoagulation of 168 colorectal adenomas allowed a complete eradication in 70% of cases, after a mean follow-up of 22 months. Advanced and obstructing tumors were treated with Nd:YAG laser to recanalize the lumen. In the upper gastrointestinal tract the recanalization of the lumen by means of laser photocoagulation improved the quality of life and survival. In fact, in our series of 308 patients treated, 1-year survival was 23% in recanalized patients and 7% in nonrecanalized patients. In the lower gastrointestinal tract, 289 cancer patients were treated and an amelioration of symptoms related to the obstruction was obtained in 93%. The current indication for photodynamic therapy is mainly the treatment of flat or ulcerative early stage tumors in the esophagus and stomach of high risk patients. Out of 17 patients treated, 14 were locally cured.

Aged↗

Improved global and regional left ventricular function after angioplasty for chronic coronary occlusion.

Percutaneous transluminal coronary angioplasty can be performed safely and effectively in patients with chronic total coronary occlusion. To investigate the effect on left ventricular function, global and regional left ventricular ejection fraction were analyzed by contrast angiography in 49 patients before and 10 +/- 6 weeks after successful recanalization. Coronary angiography at follow-up showed reocclusion in 12 patients (24%). In 37 patients with patent arteries global ejection fraction increased from 55.8 +/- 7.1% at baseline to 62.5 +/- 11.3% at follow-up (P < 0.001), and regional wall motion assessed by the centerline method improved from -1.7 +/- 1.0 to -0.6 +/- 1.5 standard deviations/chord (P < 0.001). In contrast, in patients with reocclusion neither global ejection fraction nor regional wall motion were significantly different at follow-up compared with baseline. Changes in global or regional left ventricular function after coronary recanalization were unrelated to other parameters such as severity of angina, duration of occlusion, history of myocardial infarction, presence or absence of visible collaterals, or baseline left ventricular function. Thus in patients with primarily successful recanalization of chronically occluded coronary arteries persistent vessel patency is the major determinant of global and regional improvement of left ventricular function.

Adult↗

Comparison of efficacy in crossing femoropopliteal artery occlusions with movable core and hydrophilic guidewires.

PURPOSE: Compare the recanalization rate of femoropopliteal occlusions between movable core wire guide (MG) and hydrophilic guidewire (HG). METHODS: Conventional PTA technique was used, followed by enclosed thrombolysis. The MG was used for all patients in the first 2 years, the HG in the following 2 years. Baseline characteristics were similar for the two groups of patients. RESULTS: Recanalization of 124 femoropopliteal occlusions was attempted. Technical success was achieved with the MG in 45 of 59 procedures; 42 procedures were clinically successful. Using the HG, technical success was achieved in 35 of 65 procedures; clinical success was achieved in 35 of 65 procedures; clinical success was achieved in 29 cases (p < 0.0048). At 1-year follow-up, 32 extremities improved after treatment with MG and 22 extremities after treatment with HG (p < 0.035). CONCLUSION: The results suggest that the MG should be the first choice in recanalization of femoropopliteal occlusions.

Adult↗

Sequential changes of regional circulation in cerebral infarction.

Sequential changes of regional cerebral circulation and effects of spontaneous recanalization of occluded artery on cerebral circulation were observed in 50 patients with cerebral infarction. 1) Luxury perfusion was predominantly recognized in the recanalized patients within 16 days after onset. 2) Impairment of vasomotor responses was almost the same in the recanalized patients and the occluded patients. 3) CO2 response tended to recover about 3-4 weeks after onset, but disautoregulation to induced hypertension persisted up to 2 months after onset. Some clinical problems are discussed.

Adult↗

Therapeutic colonoscopy.

Therapeutic colonoscopy has replaced or lessened to a significant degree the need or extent of traditional open surgical procedures. The common uses of therapeutic colonoscopy are hemostasis, resection and ablation of benign and malignant disease, decompression and recanalization of obstructed or dilated bowel, as well as foreign body extraction. Bleeding from arteriovenous and other vascular abnormalities can be controlled with 40% to 80% success rates using endoscopically delivered, monopolar, bipolar, or laser coagulation. The palliation of bleeding recurrent or inoperable colorectal cancer is achieved in up to 90% of patients. Virtually all pedunculated adenomas and most sessile adenomas are regularly removed colonoscopically, while large and recurrent villous adenomas in high risk individuals can be successfully managed by endoscopically delivered laser ablation techniques. Emergency colonoscopic reduction of sigmoid volvulus is performed pre-operatively and decompression of the dilated colon of non-obstructive colonic ileus is now regularly achieved. Colonic strictures have been dilated with a variety of techniques ranging from divulsion with through-the-scope balloon dilators to laser recanalization. Pre-operative endoscopic laser relief of tumor obstruction is employed to avoid preliminary or decompressing colostomy. Endoscopic laser debulking and recanalization of recurrent or inoperable cancer has been achieved with up to 80% success and various foreign bodies may be extracted from the colon with a number of endoscopic techniques. The morbidity of therapeutic colonoscopy has ranged from 1% to 2% for polypectomy to 11% for laser palliation of bleeding from advanced cancer, often with obstruction.

Adenoma↗

Stenting without thrombolysis for aortoiliac occlusive disease: experience in 14 high-risk patients.

Stenting without thrombolysis of 16 occluded iliac artery segments and one occluded infrarenal abdominal aorta was attempted in 14 patients. All patients were either considered to be prohibitive operative risks or had contraindications to thrombolytic therapy. Indications for limb reperfusion included rest pain, disabling claudication, or dry gangrene. Successful recanalization was achieved primarily in 13 patients with self-expandable Wallstents, balloon-expandable Palmaz stents, or a combination of the two stents. Follow-up was carried out in all patients in whom recanalization was successful. All stented patients showed symptomatic improvement, and the mean preprocedure ankle/brachial index, which was 0.31, improved to 0.78 after the procedure (p = 0). Complications included a vertebrobasilar stroke during the procedure in one patient, perforation during angioplasty of a stenotic but nonoccluded external iliac artery in one, and dissection of the distal external iliac artery in one. Distal embolization did not occur. Percutaneous recanalization of aortoiliac occlusions without initial thrombolysis is possible and has a high potential for technical success. Additional data and longer follow-up are still needed, but this procedure may provide a reasonable, less invasive option in some patients at high surgical risk or in patients who have contraindications to thrombolytic therapy.

Aged↗

Intracoronary thrombolysis: organizational prerequisites, technique, and results.

Reestablishing myocardial perfusion during evolving myocardial infarction may limit the ultimate extent of infarction if viable myocardial tissue is present when recanalization of the occluded vessel is achieved. This will result in improved left ventricular function and decreased mortality. In addition to their therapeutic benefits, recanalization procedures have contributed greatly to our knowledge of acute myocardial infarction. It has been demonstrated that myocardial infarction most often occurs after thrombotic occlusion of a coronary artery. This has settled a controversy that has preoccupied cardiologists for decades. Selective intracoronary administration of fibrinolytic agents is followed by recanalization in approximately 80% of cases. Therapeutic failures are attributable to occlusion caused by other factors, to inactivation of streptokinase by high antibody concentrations, and to insufficient concentrations of streptokinase at the thrombus as a result of unfavorable flow conditions.

Angioplasty, Balloon↗

Experiences in intravenous urokinase treatment of 100 acute myocardial infarction patients.

From 1980 to 1990 we treated 100 cases of AMI with i.v. urokinase (UK). According to the way of management and the dosage administered all these cases were divided into three groups: first stage of small dosage, second stage of trial big dosage, and third stage of comprehensive dosage. 36 patients of the first stage were treated with small dosage, 1-20,000 U b.i.d. for 1 week. 75% of the UK-treated and only 17% of the control group obtained relief of pain. Decrease of elevated ST reaching base line was 50 vs 8%, and FDP increased in 94%. 22 patients of the second stage were undergoing trial of big dosage. They were subdivided into larger dosage (more than 800,000 U) and smaller dosage (less than 300,000 U) groups. From the larger dosage group, 2 patients showed definite sign of recanalization, but unexpectedly 2 patients died of cardiac rupture. Since the recanalization rate of larger dosage group was 42.9%, but no case showed sign of recanalization in smaller dosage group, we are of the opinion that the dose of 800,000 U is rational for patients with symptoms' onset less than 3 h. Cardiac rupture was thought to be mostly due to reperfusion injury. Thus we designed the third stage of comprehensive dosage of UK. In this stage we used different dosage of UK and different ways of administration in 52 patients, based on the different symptoms' onset, so as to bring the effect of UK in full play. The aim of using UK is chiefly fibrinolysis as well as improvement of blood viscosity.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

[Fibrinolytic therapy of acute cerebral infarct].

On the basis of our upon own results of local intra-arterial fibrinolysis (LIF), this article gives a short overview of recently established thrombolytic therapy in acute ischemic stroke. Fifty patients with acute occlusions of vertebrobasilar arteries and 118 patients showing occlusions of branches of the internal carotid artery were treated with LIF. The Occlusion type, occlusion site and successful recanalization were associated with a favorable outcome: 92% of embolic occlusions in the vertebrobasilar territory were recanalized and resulted in 50% in a favorable outcome. In the carotid territory, optimal outcome was achieved in main stem and branch occlusions of the middle cerebral artery, due to recanalization rates of 49%-64%. In contrast, occlusions of the intracranial bifurcation of the carotid artery (carotid-"T") resulted in death in 59%. Despite the lack of randomized trials, LIF is an established form of therapy in the vertebrobasilar territory. In the carotid territory randomized clinical studies could demonstrate the efficacy of intravenous fibrinolytic therapy in some stroke patients. It can be presumed from pilot studies that LIF is superior to the intravenous version in the carotid territory.

Acute Disease↗

Intraarterial reteplase and intravenous abciximab for treatment of acute ischemic stroke. A preliminary feasibility and safety study in a non-human primate model.

We performed a preliminary feasibility and safety study using intravenous (IV) administration of a platelet glycoprotein IIb/IIIa inhibitor (abciximab) in conjunction with intraarterial (IA) administration of a thrombolytic agent (reteplase) in a primate model of intracranial thrombosis. We introduced thrombus through superselective catheterization of the intracranial segment of the internal carotid artery in 16 primates. The animals were randomly assigned to receive IA reteplase and IV abciximab ( n =4), IA reteplase and IV placebo ( n =4), IA placebo and IV abciximab ( n =4) or IA and IV placebo ( n =4). Recanalization was assessed by serial angiography during the 6-h period after initiation of treatment. Postmortem magnetic resonance (MR) imaging was performed to determine the presence of cerebral infarction or intracranial hemorrhage. Partial or complete recanalization at 6 h after initiation of treatment (decrease of two or more points in pre-treatment angiographic occlusion grade) was observed in two animals treated with IA reteplase and IV abciximab, three animals treated with IA reteplase alone and one animal treated with IV abciximab alone. No improvement in perfusion was observed in animals that received IV and IA placebo. Cerebral infarction was demonstrated on postmortem MR imaging in three animals that received IA and IV placebo and in one animal each from the groups that received IA reteplase and IV abciximab or IV abciximab alone. One animal that received IV abciximab alone had a small intracerebral hemorrhage on MR imaging. IA reteplase with or without abciximab appeared to be the most effective regimen for achieving recanalization in our model of intracranial thrombosis. Further studies are required in experimental models to determine the optimal dose, method of administration and efficacy of these medications in acute ischemic stroke.

Abciximab↗

Diagnostic and interventional radiology in the post-operative period and follow-up of patients after rectal resection with coloanal anastomosis.

Surgical treatment of carcinoma of the distal third of the rectum with anal sphincter preservation is increasingly used in accredited cancer centers. This study aimed to evaluate the diagnostic usefulness of radiological investigations in the management of patients who had undergone resection with coloanal anastomosis for carcinoma of the rectum, in the immediate post-operative period, during closure of the protective colostomy and in the follow-up of symptomatic recanalized patients. A total of 175 patients who had undergone total rectal resection with end-to-side anastomosis for carcinoma of the distal third of the rectal ampulla, most of whom had received postoperative radiotherapy, were evaluated radiologically. In the postoperative period radiological investigation was ordered only for symptomatic patients to detect pathology of the anastomosis and the pouch sutures and was used direct film abdominal radiography and contrast-enhanced radiography of the rectal stump with a water-soluble radio-opaque agent. Before closure of the colostomy, 2 months after rectal excision or approximately 4 months after if postoperative radiotherapy was given, the anastomosis and pouch of all patients, even asymptomatic ones, were studied with water-soluble contrast enema to check for normal canalization. In the follow-up after recanalization radiological examinations were done to complete the study of the large intestine if the endoscopist was not able to examine it up to the cecum. Of the 175 patients examined radiologically during the postoperative period and/or subsequent follow-up, 95 showed no pathological findings. Seventy-nine patients had fistulas of the coloanal anastomosis or the pouch, 23 of which supplied a presacral collection. In the absence of severe sepsis, the only therapeutic measures were systemic antibiotics and washing of the surgical catheters to maintain efficient operation. In 2 patients in whom transanal drainage was performed radiologically the fistula was cured in 1 week. In 36 cases of cicatricial stenosis, 17 at the coloanal anastomosis and 19 at the pouch, radiological examination always detected the lesion, correctly defining its anatomical characterisitics, nature and extension. Of the 19 cases of stenosis treated radiologically, 15 recovered an adequate intestinal calibre for tients operated on, 21 cases of reccurrence were detected. Radiological examination was requested as the first investigation in only one of these cases, for a patient with subocclusion. Radiological investigations in patients who have undergone colonanal anastomosis are of read diagnostic value in the immediate post-operative period, during closure of the protective colostomy and in the follow-up of symptomatic recanalized patients.

Anal Canal↗

[Acute myocardial infarction late after coronary artery bypass grafting: angiographic findings and results of an invasive approach].

Patients who have undergone coronary artery bypass grafting may develop acute myocardial infarction late after surgery. It is not exactly known in these patients whether acute infarction is predominantly caused by occlusion of bypass or native vessels. Also, there is no systematic and prospective data available with respect to an invasive, revascularizing therapeutic approach. Therefore, acute coronary angiograms were obtained in 21 consecutive patients with acute infarctions and remote bypass grafting to elucidate mechanisms causing myocardial infarction in these patients, and to assess results of catheter-based recanalization. Infarction was causes by acute graft occlusion in 12/21 patients. Fibrinolysis and/or PTCA of grafts was successful in 6/8 attempts, direct PTCA of a native vessel was effective in 1/2 patients, 1 patient underwent emergency re-CABG, and another patient was treated noninvasively. Occlusion of native, ungrafted vessel caused infarction in 9 patients. Direct PTCA of native vessels was effective in 6/7 of those patients, 1 patient had re-CABG, and another patients was treated non-invasively. Together, catheter-based recanalization was obtained in 13/17 attempts. Thirty-day and 1 year mortality (after discharge) was 5% (1/21 patients) and 12%, respectively. Predischarge ejection fraction was 46%. In conclusion, acute occlusion of bypass grafts is responsible for about half of all cases of myocardial infarction in patients late after surgery. Direct angiography and individually tailored catheter-based recanalization in patients with acute myocardial infarction late after surgery yield promising results.

Adult↗

Comparing short-term outcomes of femoral-popliteal and iliofemoral deep venous thrombosis: early lysis and development of reflux.

This study compares the development of reflux, recanalization, and clinical outcomes of patients with femoral-popliteal and iliofemoral deep venous thrombosis (DVT). Emphasis is placed on the relationship between early lysis of clot through thrombolysis and the development of reflux and post-thrombotic syndrome (PTS) for iliofemoral patients. A retrospective chart review was conducted of 27 femoral-popliteal DVT limbs and 11 iliofemoral DVT limbs with average follow-up of 2.3 and 2.1 years, respectively. Rates of recanalization, development of reflux, and post-thrombotic syndrome were recorded through review of duplex scans and physical examinations. All femoral-popliteal patients received anticoagulant therapy. Nine of 11 iliofemoral patients (82%) received thrombolytic therapy in addition to anticoagulants. Statistical analysis included Kaplan-Meier estimation to take into account dropout in follow-up times, and chi-squared analysis to compare final outcomes. A significantly greater proportion of iliofemoral patients (73%) than femoral patients (31%) remained asymptomatic at the end of their follow-up (p < 0.025). Because of thrombolytic therapy, 82% of iliofemoral limbs showed partial or complete lysis 4 weeks after diagnosis of clot. As expected, only 22% of femoral-popliteal limbs developed some recanalization 4 weeks after diagnosis (p < 0.005). Interestingly, no significant difference in reflux development was observed between the two groups. After an average of 2.1 years, 60% of femoral-popliteal limbs developed reflux in the deep veins vs. 64% for iliofemoral limbs. The iliofemoral DVT patients showed improved clinical outcomes in the short term compared to that of femoral-popliteal patients in this pilot study. The improved clinical outcomes could be attributed to the early lysis of clot via thrombolytic therapy for the iliofemoral group. Although the extent of reflux development was similar in both groups, iliofemoral patients still showed fewer clinical symptoms after follow-up. This may suggest that the presence of both residual obstruction and reflux, rather than either one alone, significantly increases the chances for development of PTS. Since thrombolytics eliminates at least one of these factors, residual obstruction, it may aid in decreasing development of PTS in the short term. The data in this retrospective study warrant further long-term prospective analysis of thrombolysis and its relationship with PTS.

Adolescent↗

Acute endovascular stroke therapy.

A decade after the US Food and Drug Administration (FDA) approved intravenous tissue plasminogen activator for treatment of acute ischemic stroke, the public health impact of this treatment on stroke outcome remains limited. The extremely small time window for treatment and very low recanalization rates in large artery strokes are its major shortcomings. Endovascular therapies for the treatment of acute stroke have rapidly evolved during this time period and may overcome these limitations. FDA approval of the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) concentric retriever in August 2004 for the treatment of occluded brain arteries has spurred trials of newer devices for mechanical thrombolysis in acute stroke. At present, there are two major National Institutes of Health-sponsored randomized controlled trials testing endovascular treatments in acute stroke. In this article, we provide an experience-guided review of the current approach to the endovascular treatment of acute ischemic stroke and current evidence for various strategies. We first emphasize the key aspects of patient selection, including the increasingly central role of perfusion/diffusion imaging. The technical aspects of chemical, mechanical, ultrasound-based, and multimodal approaches are provided along with the authors' own experiences. Most of the endovascular modalities tested in clinical trials show recanalization rates in the range of 50% to 65%. However, no one modality is clearly superior. In practice, multimodal treatment strategy is often employed to achieve rapid recanalization of occluded cerebral vessels and minimize chances of hemorrhage. This may become the standard of care in the future.

Clinical Trials as Topic↗

Clinical significance of early myocardial 99mTc-pyrophosphate uptake in patients with acute myocardial infarction.

Early 99mTc-pyrophosphate (PYP) scintigrams of 29 patients receiving coronary thrombolysis induced by urokinase, 3.9 +/- 1.2 hours after the onset of acute myocardial infarction (AMI), were evaluated. Intravenous 99mTc-PYP scintigraphy was performed 2.8 to 8.0 hours after the onset of AMI. All 19 patients with positive findings on early scintigrams had good recanalization, compared to only 3 of the 10 patients with negative findings. The seven patients with unsuccessful recanalization after coronary thrombolysis had total occlusion or subtotal occlusion with delayed washout of contrast material, and three of them had collaterals. The sensitivity, specificity, and predictive accuracy of positive results of early scintigraphy in predicting the presence of early reperfusion were 73%, 100%, and 90%, respectively. Patients with positive early scintigrams showed increasing regional ejection fraction and decreasing thallium defect scores from the acute stage to the chronic stage. These findings indicate that early 99mTc-PYP scintigraphy is a sensitive noninvasive technique for detecting early recanalization in infarcted vessels. The collateral flow or antegrade flow with delay is not enough to cause 99mTc-PYP uptake in a very early stage of AMI.

Aged↗

Fiberoptic study on the effects of transluminal angioplasty in experimental occlusive arterial thrombosis.

Percutaneous transluminal coronary angioplasty has been proposed as definitive therapy for coronary recanalization of occluded coronary arteries in patients with acute myocardial infarction (AMI). The effects of transluminal angioplasty (TA) on experimental occlusive canine arterial thrombi that closely simulated the clinical condition was examined by a fiberoptic method. Experimental arterial thrombosis was produced by endothelial denudation and induction of luminal stenosis. Eighteen dogs that showed total occlusion of the iliac artery with thrombi were evaluated. Seven dogs (group A) with 6-hour-old thrombi received 20,000 IU/kg intravenous urokinase (UK) but did not show recanalization. TA was performed with a Gruentzig or Simpson-Robert balloon catheter and its effect was evaluated by a vascular fibroscope. Eight dogs (group B) with 6-hour-old thrombi underwent primary TA. After TA, less than 50% luminal obstruction with residual thrombi was visualized in five dogs (71%) of group A and four dogs (50%) of group B. Residual thrombi showed a doughnut-like or globular type shape and consisted of dense fibrin networks and compact platelet aggregates. All dogs in group B received 20,000 IU/kg intravenous UK after TA, but most of them showed progression of thrombus size despite UK infusion. In conclusion, the results suggest (1) that TA is effective in recanalization of an occluded artery with aged thrombus that is resistant to thrombolytic therapy and (2) that vascular fiberscope is a useful method for evaluation of the effects of TA on occlusive arterial thrombus.

Angioplasty, Balloon↗