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Biomedical subjects

M D Dake

Publications and source records attributed to M D Dake.

At least 109 records · Page 6Linked to original sources
PubMed1985

Bronchoalveolar lavage and transbronchial biopsy for the diagnosis of pulmonary infections in the acquired immunodeficiency syndrome.

The efficacy of bronchoalveolar lavage and transbronchial biopsy in diagnosing lung infection was determined in 276 fiberoptic bronchoscopic examinations done on 171 patients with known or suspected acquired immunodeficiency syndrome. Of 173 pathogens (Pneumocystis carinii, cytomegalovirus, Mycobacterium avium-intracellulare, Cryptococcus neoformans, M. tuberculosis, Coccidioides immitis, and Histoplasma capsulatum) identified during the initial evaluation or in the subsequent month, the initial bronchoscopic examination detected 166 (96%). Bronchoalveolar lavage and transbronchial biopsy had sensitivities of 86% and 87%, respectively. When bronchoscopy included both bronchoalveolar lavage and transbronchial biopsy, the yield for all pathogens was 98% and the sensitivity for P. carinii infections was 100%. Follow-up for at least 3 weeks after examination failed to detect any additional false-negative results. Fiberoptic bronchoscopy is extremely accurate for the detection of pathogens in patients with the acquired immunodeficiency syndrome, especially when bronchoalveolar lavage and transbronchial biopsy are combined. In patients at high risk of complications from transbronchial biopsy, bronchoalveolar lavage is sufficiently accurate to be used alone.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Response of balloon-expandable endoprosthetic metallic stents subjected to over-expansion in vitro.

We attempted to evaluate the in vitro behavior and performance of balloon-expandable endoprosthetic metallic stents subjected to over-expansion (OE). Seventy-two balloon-expandable endoprosthetic stents, representing 22 models from six manufacturers, were overexpanded in vitro. Stents were initially expanded to their maximum manufacturer- recommended diameter and then over-expanded incrementally to their endpoints. Endpoints for OE were either stent disarticulation or an inability to undergo further expansion despite balloon insufflation to maximum burst pressure. Measurements of stent dimensions were recorded at each overexpanded diameter and comparisons were made to manufacturer's specifications. A total of 288 balloon-driven expansions were performed on 72 stents. Sixteen stents were expanded to large diameters (> or = 16 mm), 20 stents underwent OE of 50% or greater. One model tended to disarticulate after OE greater than 50%. There were five models that had a tendency to disarticulate after minimal OE. Five models were resistant to OE (25% or less OE) but did not disarticulate. Nearly all stents showed some degree of foreshortening with OE, while 36 stents underwent foreshortening of 30% or more. Models that are not recommended for OE include Intrastent, Intrastent DoubleStrut, NIR Royale and Omniflex. Good candidates for OE include Intrastent DoubleStrut LD, Palmaz large, Medtronic Extra Support Biliary Plus and Medtronic Flexible Biliary. Palmaz XL remains the only model available for expansion from 20 to 28 mm in diameter. For the remaining stents, OE is possible, however, caution should be used.

Catheterization↗
PubMedDate not supplied

Recurrent TIPS failure associated with biliary fistulae: treatment with PTFE-covered stents.

PURPOSE: To evaluate the efficacy of covered stents for the treatment of transjugular intrahepatic portosystemic shunt (TIPS) obstruction in human subjects with identified or suspected biliary fistulae. METHODS: Five patients were treated for early failure of TIPS revisions. All had mid-shunt thrombus, and four of these had demonstrable biliary fistulae. Three patients also propagated thrombus into the native portal venous system and required thrombolysis. TIPS were revised in four patients using a custom-made polytetrafluoroethylene (PTFE)-covered Wallstent, and in one patient using a custom-made PTFE-covered Gianturco Z-stent. RESULTS: All identified biliary fistulae were successfully sealed. All five patients maintained patency and function of the TIPS during follow-up ranging from 2 days to 21 months (mean 8.4 months). No patient has required additional revision. Thrombosis of the native portal venous system was treated with partial success by mechanical thrombolysis. CONCLUSION: Early and recurrent failure of TIPS with mid-shunt thrombosis, which may be associated with biliary fistulae, can be successfully treated using covered stents. Stent-graft revision appears to be safe, effective, and potentially durable.

Biliary Fistula↗
PubMedDate not supplied

Endovascular management of iliac vein compression (May-Thurner) syndrome.

PURPOSE: To evaluate the feasibility of endovascular techniques in treating venous outflow obstruction resulting from compression of the iliac vein by the iliac artery of the left lower extremity (May-Thurner syndrome). MATERIALS AND METHODS: A retrospective analysis of 39 patients (29 women, 10 men; median age, 46 years) with iliac vein compression syndrome (IVCS) was performed. Nineteen patients presented with acute deep vein thrombosis (DVT) and 20 patients presented with chronic symptoms. All patients presented with leg edema or pain. In the acute group, patients were treated with catheter-directed thrombolysis (120,000-180,000 IU urokinase/h) and angioplasty followed by stent placement. In the chronic group, patients were treated with use of angioplasty and stent placement alone (n = 8), or in combination with thrombolysis (n = 12). Patients were then followed-up with duplex ultrasound and a quality-of-life assessment. RESULTS: Initial technical success was achieved in 34 of 39 patients (87%). The overall patency rate at 1 year was 79%. Symptomatically, 85% of patients were completely or partially improved compared with findings before treatment. Thirty-five of 39 patients received stents. The 1-year patency rate for patients with acute symptoms who received stents was 91.6%; for patients with chronic symptoms who received stents, the 1-year patency rate was 93.9%. Five technical failures occurred. Major complications included acute iliac vein rethrombosis (< 24 hours) requiring reintervention (n = 2). Minor complications included perisheath hematomas (n = 4) and minor bleeding (n = 1). There were no deaths, pulmonary embolus, cerebral hemorrhage, or major bleeding complications. CONCLUSION: Endovascular reconstruction of occluded iliac veins secondary to IVCS (May-Thurner) appears to be safe and effective.

Acute Disease↗
PubMedDate not supplied

Percutaneous femoropopliteal graft placement.

PURPOSE: Femoropopliteal bypass surgery is now recommended for the treatment of long-segment or diffuse superficial femoral artery disease. The authors describe a technique for percutaneous placement of a prosthetic femoropopliteal graft. PATIENTS AND METHODS: The technique has been accomplished with conventional polytetrafluoroethylene graft material and a variety of implantation techniques in eight patients. RESULTS: Technical success was achieved in all patients who underwent graft placement. Grafts up to 28 cm in length were placed, and graft patency was demonstrated up to 10 months after implantation. Six of the eight patients were asymptomatic during the follow-up period; one patient who had symptoms during this time underwent thrombolysis and redilation of the distal stent, and the symptoms resolved. In the other patient with symptoms, the procedure failed clinically because of poor runoff. CONCLUSION: This study demonstrates the feasibility of percutaneous graft placement in the femoral artery, but durability must be established in relation to traditional bypass surgery before it can be recommended on a wider scale.

Adult↗
PubMedDate not supplied

Tantalum balloon-expandable stent: in vivo swine studies.

PURPOSE: The authors describe the experimental use of a balloon-expandable tantalum vascular stent in normal and atherosclerotic microswine. MATERIALS AND METHODS: Thirty-one stents (15 iliac, 13 aorta, two femoral, one renal) were placed in 11 animals. Stents were placed in both normal and stenotic atherosclerotic arteries. The animals were killed and the stents explanted 2-32 weeks after placement. Arteriography was performed just prior to death in all cases. RESULTS: All stents were patent arteriographically and on gross inspection. Histopathologic study showed a thin, smooth, endothelial-lined neointima over the segments with stents. This covering had a mean thickness of 2.9 x 10(-5) mm and appeared maximally developed 2-5 weeks after stent placement. The stent design incorporates the following engineering and clinical considerations: minimal profile and surface area and maximal expansion ratio, hoop strength, flexibility, fluoroscopic visibility, biocompatibility, and ease of placement. When compressed and mounted on the balloon catheter, the stent is flexible. This allows it to be easily maneuvered through tortuous or diseased vessels. On expansion, the stent becomes a semirigid tubular structure composed of multiple rhomboid cells. Stents with an expanded diameter of less than 11 mm can be introduced through a 7-F vascular sheath. CONCLUSION: Initial results suggest that this stent successfully incorporates a number of theoretically desirable features for a vascular prosthesis, and it may offer some advantages over previously described devices.

Angiography↗
PubMedDate not supplied

Comparative effectiveness of intravascular stents in resisting arterial vasoconstriction: evaluation with use of intact elastic (rabbit aorta) and muscular (dog carotid) arteries in an ex vivo model.

PURPOSE: The ability of three different intravascular stents (Gianturco-Roubin, Palmaz-Schatz, and CV Rad), and two different metals (stainless steel and tantalum) to resist vasoconstriction was evaluated in an intact artery ex vivo model. MATERIALS AND METHODS: Stents were deployed in 21 rabbit thoracic aortae and five dog carotid arteries, which were constricted with phenylephrine and serotonin, respectively. Vasoconstriction was measured with the use of high-frequency ultrasonic imaging. RESULTS: The maximal vasoconstriction of the control segment was 37.7% +/- 2.6 with rabbit aortae and 36.3% +/- 4.1 with dog carotid arteries, while the average maximal constriction for all segments in which stents were placed was 5.7% +/- 1.1 (P < .01). The maximal constriction of the Gianturco-Roubin stainless steel stent was 9.4% +/- 2.7 versus 7.9% +/- 1.6 with the tantalum version (P = .65). Both designs showed somewhat greater constriction compared with either the Palmaz-Schatz (3.3% +/- 0.9) or the CV Rad (1.4% +/- 1.1) stents. CONCLUSIONS: Although all of the stents tested substantially resist arterial vasoconstrictive forces, the Palmaz-Schatz and CV Rad stents resist vasoconstriction to a greater degree than the Gianturco-Roubin stents. Tantalum and stainless steel stents of the same design (Gianturco-Roubin) appear similar in their ability to resist vasoconstrictive forces.

Animals↗
PubMedDate not supplied

Hepatic laceration from wedged venography performed before transjugular intrahepatic portosystemic shunt placement.

Transjugular intrahepatic portosystemic shunt (TIPS) placement is an increasingly used, nonoperative technique for treating variceal bleeding and refractory ascites secondary to portal hypertension. Since the first clinical TIPS case in 1989, the procedure has undergone significant technical refinement to improve the safety and efficacy of shunt placement. A major technical challenge of TIPS creation is passage of the transjugular needle from the hepatic vein into the portal vein. Perforation of the liver capsule from an errant needle pass can lead to massive intraperitoneal bleeding. To minimize the number of needle passes required to enter the portal vein, investigators have devised a variety of techniques to visualize the portal vein anatomy including direct transhepatic catheterization of the portal vein, superior mesenteric artery (SMA) angiography, real-time ultrasound (US) guidance and refluxing contrast medium into the portal vein with wedged hepatic venography. While these technical improvements have made TIPS a safe and attractive alternative to conventional surgical shunts, the procedure remains technically challenging and lethal hemorrhagic complications can occur when the liver capsule is perforated during the course of the procedure. To our knowledge, there are no reported major complications directly related to the wedged hepatic venogram prior to TIPS. We describe an unusual series of severe liver injuries from wedged hepatic venography during attempts to localize the portal vein.

Adult↗
PubMedDate not supplied

Embolization of perigraft leaks after endovascular stent-graft treatment of aortic aneurysms.

PURPOSE: Perigraft leak is one of the significant problems associated with transluminal placement of stent-grafts in the treatment of aortic aneurysms. This report describes the authors' experience with transcatheter coil embolization for the treatment of perigraft leaks. MATERIALS AND METHODS: Ten patients who underwent transluminal placement of stent-grafts for the treatment of aortic aneurysms were treated. All patients had one or more tracts between the aortic wall and stent-graft or between two stent-grafts, resulting in residual aneurysm filling. All tracts were embolized by means of transcatheter deposition of platinum or steel coils. RESULTS: In all patients, all tracts were embolized completely and residual aneurysm filling was eliminated. Complete thrombosis of the aneurysm was confined on follow-up spiral computed tomography in all 10 cases. Two cases required two embolization procedures to completely embolize the tracts. No recurrent leaks or aneurysm expansions were identified on follow-up studies. CONCLUSIONS: Although long-term effectiveness remains to be proved, the initial results with transcatheter coil embolization of tracts are encouraging and suggest this technique is a safe and effective method for the management of perigraft leaks after endovascular placement of stent-grafts.

Aged↗
PubMedDate not supplied

Use of a self-expanding vascular occluder for embolization during endovascular aortic aneurysm repair.

PURPOSE: Repair of aortic aneurysms with use of stent-graft techniques may require occlusion of large branch vessels to prevent back-bleeding into the excluded aneurysmal sac. The authors describe their experience using a self-expanding vascular occluder (SEVO) to occlude flow in branch arteries during aortic stent-grafting. PATIENTS AND METHODS: Eighty-four patients (65 men, 19 women; mean age, 64 years) underwent thoracic (n = 72) or abdominal aortic (n = 12) stent-grafting. Aneurysm repair was performed using nonbifurcated Z stents covered with polyester or polytetrafluoroethylene (PTFE) fabric. SEVOs constructed from a Z stent (10-20 mm diameter) and PTFE were deployed through a separate catheter (14-20 F). RESULTS: Ten of 84 patients required embolization of large branch arteries with use of a SEVO during aortic stent-grafting (thoracic, n = 1; abdominal, n = 9). The SEVO was placed in the common iliac (n = 9) or subclavian artery (n = 1). The mean SEVO diameter was 14.7 mm (range, 10-20 mm). Eight patients undergoing SEVO embolization had immediate thrombosis of the treated artery. One patient required additional embolization with use of conventional coils. No patients had back-bleeding into the aneurysm, device migration, microembolization, or limb ischemia (mean follow-up, 140 days; range, 50-200). All 10 patients had complete thrombosis of the aortic aneurysm. CONCLUSION: Use of a novel self-expanding vascular occluding device is a safe and effective supplementary technique to occlude high-flow, large-diameter arterial branch vessels during endovascular aortic aneurysm repair.

Aged↗
PubMedDate not supplied

Acute rupture of the descending thoracic aorta: repair with use of endovascular stent-grafts.

PURPOSE: To describe the use of endovascular stent-grafts to treat acute ruptures of the descending thoracic aorta as an alternative to surgery in high-risk patients. MATERIALS AND METHODS: From July 1992 to August 1996, 95 patients underwent stent-grafting of the descending thoracic aorta for a variety of lesions. Of these, 11 patients with acute (< or = 7 days) rupture from aneurysms (n = 8) or trauma (n = 3) underwent repair with use of endovascular stent-grafts. Rupture was confirmed with preoperative imaging studies and occurred in the mediastinum (n = 9), the pleural space (n = 1), or the lung (n = 1). All patients were considered high surgical risk due to generalized cardiopulmonary disease and/or previous thoracotomies. Stent-grafts were constructed from Z stents covered with polyester fabric and delivered through a catheter under fluoroscopic control from a remote access site. RESULTS: Stent-graft deployment was successful in all patients. There were no complications of perigraft leak, stent migration, paraplegia, or intraoperative death. Two patients died in the follow-up period: one of ventricular perforation during unrelated thoracic surgery for tumor resection (day 1) and one of cardiac arrest (day 28). All others are alive (mean follow-up, 15.1 months). CONCLUSION: For acute rupture of the thoracic aorta, endovascular stent-graft repair is technically feasible and may be a therapeutic alternative to a surgical interposition graft in patients considered high risk for conventional thoracotomy. Long-term studies are necessary to determine the role of stent-grafts in preventing future aortic rupture.

Acute Disease↗