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Biomedical subjects

J Lammer

Publications and source records attributed to J Lammer.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Treatment of arterial aneurysms of the pelvic leg vessels using dacron covered nitinol stents].

PURPOSE: To evaluate the success rates of the implantation of stent grafts in the treatment of peripheral aneurysms. MATERIALS AND METHODS: In 13 patients with 15 aneurysms at the common iliac artery (n = 6), external iliac artery (n = 1), hypogastric artery (n = 2), femoral artery (n = 2) or popliteal artery (n = 4), implantation of dacron-covered nitinol stents was performed. The patients were followed up for three to 20 months (mean, 8.8 months) with intravenous digital subtraction angiography, CT or colour-coded Doppler sonography. RESULTS: In all cases, the aneurysm was successfully occluded after stent implantation. In one case with a popliteal aneurysm, kinking of the vessel caused thrombosis of the stent. The stent was successfully reopened. The aneurysm however, had to be surgically treated 9 months later. The primary and secondary patency rates at 6 months were 93% and 100%, respectively. CONCLUSION: The method described might be an alternative therapy to surgery. There are some limitations in respect of treatment of popliteal aneurysms.

Adult↗
PubMed1998

Transjugular intrahepatic portosystemic shunt and cardiac arrhythmias.

The approach to the liver for a transjugular intrahepatic porto-systemic shunt (TIPS) is through the venous system. Because catheter and guidewire system traverses the heart, cardiac arrhythmias may be expected during the procedure. We have prospectively investigated the incidence of such dysrhythmias during TIPS implantation. Twelve consecutive patients, 4 women and 8 men aged 26 to 75 years (mean, 58 +/- 13 years), were studied. Before and on the day of TIPS implantation, a 24-hour Holter recording was performed. Transjugular intrahepatic portosystemic shunt implantation was performed under local anesthesia (lidocaine) and sedoanalgesia (midazolam and fentanyl). None of the patients had concomitant cardiac disease or electrolyte disturbances. In all patients except one, TIPS implantation was successful without any technical complications. A mean of 43 +/- 5.3 hours of Holter recording was performed before and after TIPS implantation. All recordings obtained during this control period were considered inconspicuous. The mean heart rate was significantly higher during the implantation procedure of 136 +/- 37 minutes' duration (83 +/- 20 beats per minute vs 70 +/- 19 beats per minute; p < 0.01). Nine of the 12 patients experienced episodes of nonsustained supraventricular tachycardias, and one patient had two sustained supraventricular tachycardias. Frequent episodes of nonsustained ventricular tachycardias developed in 75% of the patients. It seems clear that TIPS implantation is frequently associated with supraventricular and ventricular tachyarrhythmias even in patients with apparently good cardiac condition at the beginning of the procedure. Thus close cardiac monitoring with resuscitation equipment immediately available throughout the procedure is mandatory.

Adult↗
PubMed1998

Treatment of malignant biliary obstruction with polyurethane-covered Wallstents.

OBJECTIVE: This study was undertaken to determine the safety, efficacy, and performance of polyurethane-covered Wallstents in the treatment of malignant biliary obstruction. SUBJECTS AND METHODS: This pilot study included 30 patients with malignant biliary obstruction. Palliative decompression of the obstructed bile duct was attempted with a polyurethane-covered Wallstent that is a prototype. Patients with hilar obstructions were excluded. All stents were inserted percutaneously. Kaplan-Meier analysis was used to determine stent patency. RESULTS: Effective biliary decompression was achieved in all patients initially. No acute stent-related complications occurred. The 30-day mortality rate was 20%. During follow-up, 11 stent occlusions occurred; therefore, the occlusion rate was 37%. The patency rates after 1, 3, 6, and 12 months were 96%, 69%, 47%, and 31%, respectively. Tumor growth through the stent covering that was proven both histologically and by biopsy observed in two patients, causing stent occlusion in one of them. Other reasons for stent occlusion were distal tumor ingrowth (n = 1) and biopsy-proven granulation tissue inside the stent (n = 2). Otherwise, the reasons for stent occlusion remained unclear. CONCLUSION: This prototype of a covered stent did not provide better results than did conventional uncovered stents in patients with malignant biliary obstruction. The covering did not effectively prevent tumor ingrowth in at least two patients. The stent also seems prone to premature occlusion.

Aged↗
PubMed1997

Endoluminal stent-grafts for infrarenal abdominal aortic aneurysms.

BACKGROUND: The treatment of aortic aneurysms with endovascular stents or stent-graft prostheses is receiving increasing attention as an alternative to major abdominal surgery. To define the clinical value of this technique, we prospectively studied the use of stent-graft endoprostheses made of nitinol and covered with polyester fabric for the treatment of infrarenal abdominal aortic aneurysms. METHODS: We treated a total of 154 patients at three academic hospitals. Twenty-one patients with aortic aneurysms not involving the aortic bifurcation received straight stent-grafts, and 133 patients with aortic aneurysms involving the bifurcation and the common iliac arteries received bifurcated stent-grafts. After a unilateral surgical arteriotomy, the endoprostheses were advanced through the femoral arteries and placed under fluoroscopic guidance. Computed tomography and intraarterial angiography were performed during an average follow-up of 12.5 months. RESULTS: The primary success rate, defined as complete exclusion of the abdominal aortic aneurysm from the circulation, was 86 percent in the group receiving straight grafts and 87 percent in the group receiving bifurcated grafts. In three patients the procedure had to be converted to an open surgical operation. Minor (n=13) or major (n=3) complications associated with the procedure (including 1 death) occurred in 10 percent of the patients. All patients had a postimplantation syndrome, with leukocytosis and elevated C-reactive protein levels. CONCLUSIONS: Our results suggest that endovascular treatment of infrarenal abdominal aortic aneurysms is technically feasible and can effectively exclude abdominal aortic aneurysms from the circulation. With further refinement, endoluminal repair may emerge as an interventional strategy to treat infrarenal aortic aneurysms, especially in patients at high surgical risk.

Adult↗
PubMed1997

Biliary Wallstent endoprosthesis in malignant hilar obstruction: long-term results with regard to the type of obstruction.

AIM: To evaluate the clinical efficacy of percutaneously placed biliary Wallstents in the management of malignant hilar obstruction with regard to the obstruction type. PATIENTS AND METHODS: Sixty-six Wallstents were inserted in 41 patients with inoperable hilar obstruction: 13 patients had a type I obstruction according to Bismuth-classification, 18 a type II, eight a type III, and two a type IV obstruction, respectively. Clinical follow-up data were obtained from all the patients and the referring physicians. RESULTS: Stent placement was technically successfully in all patients. The procedure-related death rate was 2% (one patient), but the overall 30-day mortality rate was 39%, mostly due to advanced malignant disease, cardiac failure or pneumonia. Stent occlusion was found in 11 patients (27%) after 87 days (mean; range, 8-190 days). After stent placement, the mean stent patency was 96 days and the mean survival was 131 days with no significant difference between patients with obstruction type I, II and III. Multivariate analysis revealed that patients with obstruction due to gallbladder carcinoma had a significantly shorter survival than patients with cholangio-carcinoma or hilar obstruction due to metastases. CONCLUSION: Overall, the insertion of Wallstent endoprostheses offers moderate results for palliation of hilar biliary obstruction regardless of the type of obstruction. In patients with cholangiocarcinoma, long-term results are good even for complicated strictures (type III). In patients with hilar obstruction due to gallbladder carcinoma the outcome is generally poor, regardless of the type of obstruction.

Adult↗
PubMed1997

The first 15 months of transluminal abdominal aortic aneurysm management: a single centre experience.

OBJECTIVES: To assess the early experience with the transfemorally placed modular endovascular MinTec graft (TPEG) for abdominal aortic aneurysm (AAA). DESIGN: One single centre prospective evaluation of the endograft procedure as well as early postoperative results. SETTING: An academic teaching hospital. PATIENTS: 30 consecutive patients treated during a period of 15 months. RESULTS: Peri- and postoperative morbidity and mortality were evaluated according to the recommendations of the Ad Hoc Committee on Reporting Standards. The endograft procedure was successful in 28 patients (93.4%); two patients (6.6%) needed conversion into open conventional y-graft replacement; one patient died 36 days following intervention from multiple organ failure. Another patient died from pancreatitis unrelated to the implantation. Endoleaks were treated by "overstenting" or distal extension of the endografts, but conversions were unnecessary. Five severe adverse events were noted in four patients. CONCLUSIONS: TPEG is a feasible but technically demanding procedure, requiring both surgical techniques and catheter skills. The potential for less operative morbidity and simpler aneurysm management compared to conventional open surgery may be present. Close follow-up of patients is necessary to understand the development and treatment of endoleaks.

Aged↗
PubMed1997

Endovascular AAA treatment: expensive prestige or economic alternative?

OBJECTIVES: To compare the costs of endovascular aneurysm treatment versus open surgery during the perioperative period. METHODS: Retrospective analysis of a consecutive series of 44 patients undergoing infrarenal abdominal aneurysm repair from February 1995 to March 1996 at a university teaching hospital. RESULTS: No endovascular procedure was converted to open repair. Operative time was shorter for endovascular treatment (207.6 min vs. 229.1 min, n.s.), as well as postoperative intensive care unit stay (ICU, 22.7 h vs. 55.0 h, p = 0.017) and the postoperative recovery period (5.6 days vs. 13.3 days, p < 0.001). Open surgery generated significantly more costs (25,374.07 ECU vs. 22,268.78 ECU, p < 0.001), despite evaluation and a more expensive endovascular procedure (10,699.48 ECU vs. 4032.01 ECU, p < 0.001). During the study, costs for open surgery exceeded the cost for endovascular treatment by 13.95%. CONCLUSIONS: Endovascular aneurysm treatment is cost effective and less expensive than open surgery. The main reason for cost saving is faster patient recovery after surgery, associated with a shorter LOS in the patients treated with endovascular procedure.

Aged↗
PubMed1997

Treatment of abdominal aortic aneurysms with transfemoral placement of stent-grafts: complications and secondary radiologic intervention.

PURPOSE: To determine the rate of complications of transluminally placed endovascular stent-grafts in patients with abdominal aortic aneurysms and to assess efficacy of secondary radiologic intervention. MATERIALS AND METHODS: In 28 patients, covered nitinol stents were implanted. Frequency and outcome of complications were evaluated after stent-graft placement (mean follow-up, 8.2 months). RESULTS: In 27 patients, 11 tube and 16 bifurcated grafts were implanted successfully. In one (4%) patient, distal migration of a bifurcated graft necessitated conversion to standard open repair. Technical success rates (successful deployment of the device and complete exclusion of the aneurysm at intraoperative angiography) for bifurcated and tube grafts were 24% (four of 17 patients) and 91% (10 of 11 patients). After surgery, leaks were seen in six bifurcated and five tube grafts. After secondary intervention, the final exclusion rate for bifurcated and tube grafts was 88% (15 of 17 patients) and 100% (11 of 11 patients), respectively; the overall success rate was 93% (26 of 28 patients) for exclusion of aortic abdominal aneurysms. Stent-graft thrombosis necessitated local thrombolysis in one patient. Overlapping of accessory renal arteries occurred in two patients. CONCLUSION: Complications after stent-graft placement in abdominal aortic aneurysms are frequent. Secondary radiologic intervention is successful in most cases.

Aged↗
PubMed1997

Evaluation of abdominal aortic aneurysm for stent-graft placement: comparison of gadolinium-enhanced MR angiography versus helical CT angiography and digital subtraction angiography.

PURPOSE: To determine whether magnetic resonance (MR) angiography can be used alone to evaluate abdominal aortic aneurysms (AAAs) for endovascular placement of stent grafts. MATERIALS AND METHODS: Sixty-one patients with AAAs underwent gadolinium-enhanced MR angiography of the abdominal aorta and pelvic arteries. Measurements of the size and extent of the AAAs were compared with helical computed tomographic (CT) and digital subtraction angiographic measurements; 95% confidence intervals for the differences in the means were determined. RESULTS: Because of the larger field of view, MR angiography was superior to CT angiography in assessing visceral iliac artery disease. Both modalities were equal in evaluating the proximal extent of the AAA (mean difference, -0.16 mm; 95% CI, -0.31, 0.64) and in measuring all aortic dimensions (e.g., mean difference in the proximal neck diameter, -0.74 mm; 95% CI, -0.98, -0.49). MR angiography was inferior to CT angiography in depicting accessory renal arteries (seven of 12) and in grading renal artery stenoses (sensitivity, 100% [95% CI, 0.90, 1.00]; specificity, 84% [95% CI, 0.74, 0.91]). CONCLUSION: Gadolinium-enhanced MR angiography is a fast, reliable means of providing all the information relevant to the preoperative assessment of endovascular aortic stent-graft placement.

Adult↗
PubMed1996

Stenoses of the first segment of the vertebral artery: difficulties in angiographic diagnosis.

Pathology at the origin of the vertebral artery may be the cause of incapacitating vertebrobasilar insufficiency (VBI). Preoperative diagnosis is made primarily on angiographic criteria. We compared intraoperative and angiographic findings in 30 patients and found important diagnostic discrepancies in patients with a caudal, ventral or dorsal origin of the vertebral artery. In their angiograms, vessel superimposition led us to over look 3 ostial stenoses and 10 stenoses due to kinking. Angiographic assessment of patients with VBI can be difficult. Adequate visualisation of the origin of the vertebral artery is mandatory for accurate diagnosis.

Aged↗
PubMed1996

Spiral CT angiography: study of stenoses and calcification at the origin of the vertebral artery.

The origin of the vertebral artery may be difficult to show on sonography or conventional angiography. Our aim was to evaluate the accuracy of CT angiography (CTA) in detecting arteriosclerotic changes in the first segment (V1) of the vertebral artery. We performed CTA and intra-arterial digital subtraction angiography (DSA) on 24 patients with vertebrobasilar insufficiency. The ostium and the V1 segment were examined. Stenosis was assessed on a three-grade scale, and calcification and the degree of kinking were recorded. DSA and CTA results were compared. The ostium of the artery was seen in all cases on CTA and in 33 of 47 cases with DSA. All ostial stenoses diagnosed on DSA were seen with CTA. CTA revealed 4 stenoses in cases in which angiography proved inadequate, 11 zones of calcification and 5 cases of luminal reduction due to calcified plaques undetected on DSA. In the V1 segment DSA and CTA showed 3 stenoses, 9 cases of kinking, 1 of coiling and 4 stenoses due to kinking. CTA also demonstrated 4 additional stenoses, 2 cases of kinking and 3 stenoses due to kinking.

Aged↗
PubMed1996

Two cases of fractured esophageal nitinol stents.

We report here on two cases of fractured nitinol stents in the esophagus. In case 1, the correctly inserted stent broke spontaneously shortly after insertion. In a second case, a nitinol stent broke after laser application due to tumor ingrowth with massive bleeding. In both cases, a second stent was implanted in order to reestablish food passage. The fracture of the stent in case 1 seemed to be caused by defective material, whilst in case 2 the stent broke because of thermal overstrain during laser application. The use of electrocoagulation or laser in the stent area should therefore be avoided; argon plasma coagulation may offer an effective alternative in treating tumor ingrowth. As there was a risk from piercing broken filaments with the second stent, covering a fracture using stents with tight walls or plastic tubes seems to be a more effective approach than the inserting an uncovered stent type.

Aged↗
PubMed1996

[Contrast media in peripheral angiography: does cost reduction mean loss of quality and safety? A reevaluation based on a randomized double-blind comparative study of ioxaglate versus iopromide].

PURPOSE: To evaluate whether meglumine-sodium-ioxaglate (Hexabrix) and iopromide (Ultravist) are identically appropriate for peripheral angiography. Outcome variables were pain, image quality and adverse events. METHODS: Sixty patients were included in a randomised double-blind study. In all patients an intraarterial digital subtraction angiography (i.a. DSA) of iliac and peripheral arteries was performed. RESULTS: Analysis of the study revealed no significant difference between both contrast media in terms of the main and additional outcome variables. In comparison to iopromide, ioxaglate caused milder pain sensations (VAS 4.70 vs. 7.76, p = 0.25). Mild adverse events were observed more frequently in ioxaglate angiography (11% vs. 0%, p = 0.1). CONCLUSION: Both contrast media seem to be appropriate for peripheral angiography using DSA technique. Ioxaglate causes a cost reduction of about 20-35%. However, an increase of mild adverse reactions up to 11% to 15% has to be accepted.

Adult↗
PubMed1996

Benign biliary obstruction: is treatment with the Wallstent advisable?

PURPOSE: To evaluate the effectiveness of the self-expanding Wallstent in the treatment of benign biliary strictures. MATERIALS AND METHODS: Twenty patients with benign biliary strictures were included in this retrospective study. Seven patients had chronic pancreatitis, two had fibrous papillary stenosis, one had primary sclerosing cholangitis, and 10 had postsurgical strictures, including four who had a stenosed bilidigestive anastomosis. Primary and secondary patency of the stents and clinical outcome after stent insertion were evaluated. RESULTS: Stent placement was successful in all patients. At the end of the observation period, which lasted 3-78 months (mean, 31.2 months +/- 4.5 [standard error]), 10 patients were alive. Median primary patency was 32 months +/- 8.7. In 10 patients, patency was preserved during the observation period (two with secondary patency). Six patients had a good clinical result. Among the other four patients, one had recurrent cholangitis, one had a biliary abscess, and two had stent revisions. In the other patients, stents became occluded after 3-55 months. The reason for stent occlusion was a stone in one patient; in the others, the causes were not proved. CONCLUSION: Results of stent placement for treatment of benign biliary strictures are not encouraging. However, the patient population is too limited to allow final conclusions.

Cholestasis↗
PubMed1996

Common bile duct obstruction due to malignancy: treatment with plastic versus metal stents.

PURPOSE: To compare the clinical efficacy and treatment costs of plastic versus metal biliary stents. MATERIALS AND METHODS: In a randomized trial, 101 patients with malignant common bile duct obstruction underwent transhepatic stent implantation and were followed up until death. Patients were stratified into risk and nonrisk groups. Forty-nine patients received 12-F plastic stents, and 52 received expandable metal stents. Plastic endoprostheses were placed in a two-step procedure; metal stent, in a single procedure. Kaplan-Meier analyses were used to compare patient survival and stent patency rates. RESULTS: The 30-day mortality rate was significantly lower for metal stents (five of 52 [10%]) than plastic stents (12 of 49 [24%]; P = .05). The obstruction rate was 19% (10 of 52; median patency, 272 days) for metal stents and 27% for plastic stents (13 of 49; median patency, 96 days; P < .01). Median time until death or obstruction was longer for metal stents (122 vs 81 days; P < .01). Placement of metal stents was associated with shorter hospital stay (10 vs 21 days; P < .01) and lower cost ($7,542 vs $12,129; P < .01). CONCLUSION: Use of self-expanding metal stents appears to show substantial benefits for patients and to be cost-effective.

Aged↗
PubMed1996

Palliative treatment of obstructing esophageal cancer with nitinol stents: value, safety, and long-term results.

OBJECTIVE: The purpose of our study was to evaluate the effectiveness of nitinol stents for palliation of dysphagia due obstructing esophageal cancer, safety of stent placement, and long-term results. SUBJECTS AND METHODS: Self-expanding uncoated nitinol stents were inserted either radiologically (14 patients) or endoscopically (12 patients) on an outpatient basis in 26 consecutive patients with dysphagia grade 3 or 4 caused by incurable malignant obstructions in the middle or distal third of the esophagus (n = 22) or at esophagojejunal anastomoses (n = 4). No esophagotracheal fistulas were seen in any patient. In 22 patients prior treatments had failed. Following insertion, the stent lumen was dilated to the maximum diameter. Finally, esophagography or esophagoscopy was done to confirm the position of the stent and patency of the esophageal lumen. Twenty-four hours after the procedure, esophageal function was investigated by a barium swallow. Patients were encouraged to ingest solid food thereafter. Improvement in dysphagia was evaluated 1 week after stent placement and during monthly interviews. Complications were defined as major (aspiration, bleeding, stent misplacement or dislocation, perforation) or minor (reflux esophagitis, chest pain, pharyngeal discomfort). Tumor ingrowth or overgrowth was considered a treatment failure. Twenty-three patients (88%) were followed until death: three patients (12%) were followed for a mean of 14 months. RESULTS: Exact positioning of the stent and dilation to its maximum diameter were technically feasible in all patients. No stents were placed in the stomach. Patency of the esophageal lumen was successfully restored in 25 patients. In one patient a broken strut of the stent after dilation caused a partial obstruction, which was detected endoscopically. Two patients had recurrent dysphagia due to tumor ingrowth or overgrowth, one after 1 month and the other after 3 months. In these patients an additional overlapping stent was successfully placed. No procedure-related mortalities or major complications occurred. The mean dysphagia grade of 3.5 was improved to a mean grade of 0.6 after stent placement. All patients could take liquids within the first 24 hr. Fifteen patients improved to dysphagia grade 0, seven patients to grade 1, and four patients to grade 2 within 1 week after the procedure. Twenty-three patients (88%) died during the follow-up period (mean survival, 5 months) as a result of their disease. Latest evaluation of the mean dysphagia grade was 0.7. Three patients (12%) are still alive (mean survival, 14 months) with a dysphagia grade 1 in one patient and grade 0 in two. CONCLUSION: Implantation of nitinol stents proved to be an effective and safe method of palliating severe dysphagia in patients with obstructing esophageal cancer. The improvement in dysphagia was impressive and long lasting. Placement of the stents was feasible without major procedure-related complications.

Aged↗
PubMed1995

Hepatic artery embolotherapy of hepatic metastases from carcinoid tumors: value of using a mixture of cyanoacrylate and ethiodized oil.

OBJECTIVE: Transcatheter embolization of the hepatic arterial supply is a well-known palliative treatment of tumor deposits in the liver. We performed a prospective study to evaluate the use of a mixture of N-butyl-2-cyanoacrylate and ethiodized oil with which a permanent vascular occlusion can be obtained, as an embolizing agent for transcatheter hepatic artery embolization for treatment of carcinoid hepatic metastases. SUBJECTS AND METHODS: Six patients had clinical symptoms from hormonal release by carcinoid hepatic metastases as well as elevated levels of 5-hydroxyindole acetic acid (5-HIAA) in the urine. Unilobar sequential transcatheter embolization of both the hepatic artery and the segmental hepatic arteries of both lobes of the liver was performed with a mixture of N-butyl-2-cyanoacrylate and ethiodized oil. CT and CT arterial portography (CTAP) were done to assess hepatic metastases and were used to monitor follow-up. Each patient had three CTAP studies; the third CTAP, performed 3 months after complete arterial devascularization, was compared with the first CTAP to evaluate tumor size. CT studies were performed routinely every 3 months thereafter and were compared with the initial CT scan to evaluate further tumor regression or progression. Tumor decrease and biochemical and symptomatic response rates were defined according to World Health Organization criteria. All complications and side effects of the treatment were documented. RESULTS: All patients showed complete symptomatic relief after embolization. The previously elevated levels of 5-HIAA in the urine returned to normal in three patients and in the other three patients were reduced by a mean of 89% of preembolization values. A decrease in tumor size by more than 50% was demonstrable in one patient; in five patients, hepatic lesions decreased in size by 25-50%. No new sites of metastatic liver disease were demonstrable in any patient during follow-up. No deaths or serious complications were directly attributable to the embolization procedure. All patients are alive after 12, 17, 18, 19, 19, and 19 months (mean, 17.3 months), respectively, with permanent relief of symptoms so far. CONCLUSION: Transcatheter embolization of both the hepatic artery and the segmental hepatic arteries with a mixture of N-butyl-2-cyanoacrylate and ethiodized oil provided excellent palliation in patients with carcinoid hepatic metastases. Complete and long-lasting relief of symptoms, a significant decrease or normalization of levels of 5-HIAA in the urine, and a reduction of metastatic tumor in the liver seem most likely to be the effect of sustained ischemia obtained with this permanent embolizing agent.

Carcinoid Tumor↗