True-lumen collapse in aortic dissection: part I. Evaluation of causative factors in phantoms with pulsatile flow.

PURPOSE: To investigate the causative factors in true-lumen collapse in a model of aortic dissection. MATERIALS AND METHODS: Phantoms with an aortic arch, true and false lumina with abdominal branch vessels, and a distal bifurcation were used to model a Stanford type B aortic dissection. The effects of anatomic factors (entry-tear size, branch-vessel flow distribution, fenestrations, distal reentry communication) and physiologic factors (peripheral resistance in the branch vessels, pump output and rate, vascular compliance) on true-lumen collapse were investigated. The morphology of the true lumen was observed. Branch pressures and flow rates were measured. RESULTS: True-lumen collapse was induced and was exacerbated by an increase in the size of the entry tear, a decrease in the false-lumen outflow caused by occluding the false-lumen branch vessels, and an increase in the true-lumen outflow caused by lowering the peripheral resistance in true-lumen branch vessels. Two kinds of true-lumen collapse depended on pump output. With low pump output and low outflow resistance from the true lumen, the true lumen collapsed. With high pump output and low inflow resistance in the false lumen, the true lumen was compressed. Distal reentry communication between the true and false limbs was more effective than aortic fenestrations in preventing true-lumen collapse. CONCLUSION: True-lumen collapse in this dissection model strongly depends on the difference in the ratios of inflow capacity to outflow capacity in the true and false lumina. Both anatomic and physiologic factors can affect true-lumen collapse.

True-lumen collapse in aortic dissection: part II. Evaluation of treatment methods in phantoms with pulsatile flow.

PURPOSE: To discover and evaluate the effective treatment methods to prevent or relieve true-lumen collapse in models of aortic dissection. MATERIALS AND METHODS: Two phantoms were built to simulate type B aortic dissection. After true-lumen collapse was induced, experiments were conducted to evaluate the effectiveness of clinically relevant variables in relieving the collapse. Variables included entry-tear size, branch-vessel flow distribution, distal reentry communication between the true and false limbs, aortic fenestrations, and pump output. To test the effect of closing the entry tear, a stent-graft was deployed over the entry tear under physiologic conditions in a mock-flow loop. The difference in the effect of each variable on the prevention and relief of true-lumen collapse was also investigated. RESULTS: It was more difficult to relieve true-lumen collapse than it was to prevent it. Placement of a stent-graft over the entry tear was the most effective method of relieving true-lumen collapse. Less-effective procedures included opening a false-lumen outflow branch and opening the distal reentry branch. Opening the fenestration-branch loops, meant to simulate the creation of artificial fenestrations in the intimal flap, did not relieve true-lumen collapse. CONCLUSION: The definitive treatment for true-lumen collapse in aortic dissection is direct repair of the entry tear to decrease false-lumen inflow. Otherwise, increasing the false-lumen outflow and/or creating distal fenestrations between the true and false lumina distal to the level of the compromised aortic branch are less-effective alternatives.

Aortic aneurysmal disease: assessment of stent-graft treatment-CT versus conventional angiography.

PURPOSE: To compare computed tomographic (CT) angiography and conventional angiography for determining the success of endoluminal stent-graft treatment of aortic aneurysms. MATERIALS AND METHODS: Forty patients underwent conventional angiography and CT angiography following treatment of aortoiliac aneurysms with endoluminal stent-grafts. Six additional sets of conventional angiographic-CT angiographic examinations were performed in five patients after placement of additional stent-grafts or coil embolization to treat perigraft leakage. Three faculty CT radiologists who were blinded to patient clinical data and outcome independently interpreted the CT angiograms, and three faculty angiographers, who were not involved in the stent-graft deployment, interpreted the conventional angiograms. Images were assessed for the presence of postdeployment complications. A reference standard was developed by experienced radiologists using all available images and clinical data. Sensitivities, specificities, and kappa values were calculated. RESULTS: Perigraft leakage was the most commonly identified complication. Twenty perigraft leaks were detected in the results of 46 examinations. Sensitivities and specificities for detecting perigraft leakage were 63% and 77% for conventional angiography and 92% and 90% for CT angiography, respectively. The kappa value was 0. 41 for conventional angiography and 0.81 for CT angiography. CONCLUSION: CT angiography is the preferred method for establishing the presence of perigraft leakage following treatment of aortoiliac aneurysms with stent-grafts.

Management of misplaced or migrated endovascular stents.

PURPOSE: To report experience with techniques for management of misplaced or migrated endovascular stents. MATERIALS AND METHODS: During a 5-year period, percutaneous management of 27 misplaced or migrated endovascular stents (16 Palmaz, 11 Wallstents) in 25 patients was attempted. The 17 venous and 10 arterial stents were rescued from the aorta (n = 9), inferior vena cava (IVC) (n = 4), transjugular intrahepatic portosystemic shunt/IVC (n = 2), right atrium (n = 3), right ventricle (n = 2), pulmonary artery (n = 2), iliac vein (n = 2), iliac artery (n = 1), superior vena cava (n = 1), and superior mesenteric vein (n = 1). RESULTS: Stent management was successful in 26 of 27 cases (96%). Eleven stents were removed percutaneously, two were repositioned and removed with a minor surgical procedure, and 13 were repositioned and deployed in a stable alternate location. The only complication was the development of tricuspid insufficiency in the single case in which the procedure failed (4% complication rate). This patient's stent was eventually surgically removed from the right ventricle. CONCLUSION: Misplaced or migrated endovascular Palmaz and Wallstents can be effectively managed with few complications by using a variety of percutaneous techniques.

Percutaneous balloon fenestration and stenting for life-threatening ischemic complications in patients with acute aortic dissection.

OBJECTIVES: Acute aortic dissection frequently causes life-threatening ischemia of end-organs, historically associated with mortality exceeding 60%. Reperfusion with the use of interventional radiologic methods has evolved as a promising treatment. We report results of our initial 6 years of experience with percutaneous balloon fenestration of the intimal flap and endovascular stenting. METHODS: Forty patients (32 male and 8 female) with a median age of 53 years (range 16-86 years) underwent percutaneous treatment for peripheral ischemic complications of 10 type A and 30 type B acute aortic dissections since 1991. Twenty patients had ischemia of multiple organ systems. Thirty patients had renal, 22 had leg, 18 had mesenteric, and 1 had arm ischemia. RESULTS: Fourteen patients were treated with stenting of either the true or false lumen combined with balloon fenestration of the intimal flap, 24 with stenting alone, and 2 with fenestration alone. Successful revascularization was achieved in 93% +/- 4% (+/-70% confidence levels) of patients (37/40). Nine patients had procedure-related complications. The 30-day mortality rate was 25% +/- 7% (10/40), often related to irreversible ischemia of intra-abdominal organs that was present before the procedure. Of the remaining 30 patients, 5 have died and the remaining 25 continue to have relief of ischemic symptoms at a mean follow-up of 29 months. CONCLUSION: Percutaneous balloon fenestration of the intimal flap and endovascular stenting is an effective treatment for life-threatening ischemic complications of acute aortic dissection.

Mycotic aneurysms of the thoracic aorta: repair with use of endovascular stent-grafts.

PURPOSE: Standard therapy of mycotic aneurysms in the descending aorta consists of thoracotomy and in situ graft placement or extraanatomic bypass. The alternative use of endovascular stent-grafts was evaluated for management of infected aneurysms of the thoracic aorta. MATERIALS AND METHODS: In a retrospective analysis during a 5-year period, 112 patients underwent stent-graft placement for thoracic aortic aneurysms. Three patients (mean age, 68.6; range, 64-70 years) had mycotic thoracic aneurysms. Stent-grafts were constructed from Z stents covered with polyester fabric and were delivered remotely through a catheter under fluoroscopic guidance. RESULTS: Complete thrombosis of the mycotic aneurysms was achieved in all patients. One patient required a second separate stent-graft placement procedure because of migration of the initial device; the second patient underwent surgical repair of a ruptured mycotic abdominal aortic aneurysm followed immediately by stent-graft placement for a chronic mycotic thoracic aneurysm; a third patient underwent repair of two infected false aneurysms secondary to complete rupture of a surgical interposition graft. There were no complications of persistent bacteremia despite placement of the stent-graft device at the site of primary infection, reinfection, delayed rupture, paraplegia, distal emboli, or surgical conversion. One patient died of cardiac arrest at 25 months; there were no perioperative deaths (< or = 30 days). The remaining two patients were alive and well at median follow-up of 24 months (range, 4-25 months). CONCLUSION: Endovascular stent-grafts combined with antibiotic therapy may be an alternative to conventional thoracotomy in managing mycotic aneurysms of the descending thoracic aorta.

Treatment of aortoiliac aneurysms with use of single-piece tapered stent-grafts.

PURPOSE: The authors describe their experience with the use of single-piece, tapered stent-grafts for the treatment of abdominal aortic or aortoiliac aneurysms. MATERIALS AND METHODS: Single-piece, tapered stent-grafts were placed in 15 patients for the treatment of abdominal aortic aneurysms with small distal necks (n = 13), and aortoiliac aneurysms (n = 2). There were 13 men and two women who ranged in age from 59 to 83 years (mean, 71 years). Usual open surgery was considered high risk in all patients because of comorbid medical conditions. The stent-grafts were made of Z stents covered with polytetrafluoroethylene (PTFE). Additional stent-grafts needed to treat perigraft leaks were made of Z stents covered with woven polyester (n = 5), Wallstents covered with PTFE (n = 2), Z stents covered with PTFE (n = 1), and a PTFE-covered Palmaz stent (n = 1). After stent-graft placement, the contralateral iliac artery was occluded by a blocking device composed of either a PTFE-covered Palmaz (n = 1) or Z stent (n = 13), and a femoral-femoral bypass was created. RESULTS: After placement of the stent-grafts, immediate perigraft leaks were observed in eight patients (53%). These were at the proximal (n = 5) or the distal end (n = 3). All, except one, were treated successfully with additional stent-grafts. The one failure was in a patient who developed aortic rupture after balloon dilation, requiring open surgical repair. Second procedures were required in four patients (27%), including three leaks treated successfully with coil embolization and/or a back-up stent-graft, and one stent-graft migration and thrombosis treated by thrombolysis and placement of an additional stent-graft. One patient died of respiratory failure 23 days after placement of the stent-graft. The mean follow-up was 12 months (range, 4-26 months). On the last follow-up, the aneurysms in the 13 living patients remained thrombosed. CONCLUSION: Treatment of aortoiliac aneurysms with use of single-piece, tapered stent-grafts is feasible in selected patients. The morbidity and mortality rates compare favorably with those of the open surgical procedures in a high-risk population. Further improvements in the technique and longer follow-up data are needed before this procedure can be recommended for the treatment of all aortoiliac aneurysms.

Transbronchial Palmaz stent placement for tracheo-bronchial stenosis.

PURPOSE: Evaluation of the efficacy of transbronchial Palmaz stent placement in the treatment of tracheo-bronchial narrowing. MATERIALS AND METHODS: Twelve patients with stenoses of the tracheo-bronchial tree were treated with balloon-expandable Palmaz stents. Etiology was anastomotic stenosis after lung transplantation (n = 3), bronchogenic carcinoma (n = 2), external compression from thoracic aortic aneurysm (n = 2), Mycobacterium tuberculosis (n = 1), esophageal carcinoma (n = 1), after lobectomy (n = 1), after lobectomy and endobronchial radiation (n = 1), and lye ingestion (n = 1). All patients had respiratory symptoms, radiologic findings of persistent atelectasis, or worsening pulmonary function tests. Bronchoscopy was used to delineate the stenosis prior to intervention. With use of fluoroscopic guidance, stents were placed in the mainstem bronchus (n = 11), lower lobe bronchus (n = 5), bronchus intermedius (n = 5), trachea (n = 3), and middle lobe bronchus (n = 1). RESULTS: Initial technical success was achieved in all patients. Ten of the 12 patients (83%) had improvement of clinical pulmonary signs or symptoms. During follow-up, five patients died. One was lost to follow-up and was presumed dead. The 30-day mortality rate was 17% (two of 12 patients). The two complications were superficial laceration of the bronchial mucosa during balloon dilation in one patient and compression of stents by a thoracic aortic aneurysm in another patient. CONCLUSION: Initial results suggest that transbronchial Palmaz stent placement is a feasible and effective method of treating tracheo-bronchial stenosis.

True lumen obliteration in complicated aortic dissection: endovascular treatment.

PURPOSE: To evaluate endovascular treatment of ischemic complications caused by true lumen obliteration in aortic dissection. MATERIALS AND METHODS: Endovascular techniques were used to treat true lumen obliteration in 11 patients with complicated aortic dissection. In all cases, the true lumen was compressed to a paper-thin sliver by the expanded false lumen. Two patients had Stanford type A (chronic) and nine had type B (six acute, three chronic) dissections. Obliteration of the true lumen was associated with branch vessel ischemia that included renal (n = 7), mesenteric (n = 6), and lower-extremity (n = 6) arterial compromise. Two patients were treated with aortic stents, four with balloon fenestration of the intimal flap, and three with both stent placement and fenestration. In two patients, ischemic complications caused by true lumen obliteration could not be treated with endovascular techniques. RESULTS: Revascularization was technically successful with relief of clinical symptoms in nine patients. Revascularization was unsuccessful in one patient in whom surgical revascularization of the superior mesenteric artery was necessary and in one in whom hypertension was managed medically. One patient developed thrombosis of a renal artery in which a stent had been placed. The 30-day mortality rate was 9%, and the mean follow-up was 10.1 months (range, 2 weeks to 39 months). CONCLUSION: True lumen obliteration can be safely and effectively treated with endovascular stent placement and balloon fenestration.

Aortic dissection: percutaneous management of ischemic complications with endovascular stents and balloon fenestration.

PURPOSE: The purpose of this study was to evaluate endovascular stenting (EVS) and balloon fenestration (BF) of intimal flaps for the management of lower extremity, renal, and visceral ischemia in acute or chronic aortic dissection. METHODS: Twenty-two patients (16 male, 6 female) with a median age of 53 years (range 35 to 77 years) underwent percutaneous treatment for peripheral ischemic complications of 12 type A (five acute, seven chronic) and 10 type B (nine acute, one chronic) aortic dissections. RESULTS: Ten patients had leg ischemia, 13 had renal ischemia, and 6 had visceral ischemia. Sixteen patients were treated with EVS including 11 with renal, 6 with lower extremity, 2 with superior mesenteric artery, and 2 with aortic stents. Three patients had BF of the intimal flap, and three had BF in combination with EVS. Revascularization with clinical success was achieved in all 22 patients. Two patients died 3 days and 13.4 months after the procedure was performed, respectively. Of the remaining 20 patients, 1 is lost to follow-up, and 19 have persistent relief of clinical symptoms. Mean follow-up time is 13.7 months (range 1.1 to 46.5 months). One case was complicated by guidewire-induced perinephric hematoma. CONCLUSION: EVS and BF provide a safe and effective percutaneous method for managing peripheral ischemic complications of aortic dissection.

Unilateral absence of right-lung perfusion with normal ventilation on radionuclide lung scan as a sign of aortic dissection.

A case of aortic dissection with unilateral absence of right-lung perfusion and normal ventilation on radionuclide ventilation/perfusion (V/Q) lung scan is presented with a review of the literature. Anticoagulation or thrombolytic therapy for presumed pulmonary embolism may be catastrophic if the clinical syndrome and V/Q scan appearance are instead due to aortic dissection. With this V/Q scan appearance, these therapies should not be instituted unless pulmonary embolism is diagnosed by pulmonary arteriography.

Diagnosis of prostatic carcinoma: value of random transrectal sonographically guided biopsies.

OBJECTIVE: We studied the efficacy of random, transrectal sonographically guided biopsies in the diagnosis of prostatic carcinoma in a high-risk population. SUBJECTS AND METHODS: During a 2-year period, 570 transrectal sonographically guided prostatic biopsies were done because of clinical findings suggestive of prostatic carcinoma. Biopsies of hypoechoic lesions that were suggestive of carcinoma and segmental random biopsies of normal-appearing lobes of the prostate were performed. Transrectal sonographic findings were correlated with results of pathologic examination of the biopsy specimen and with surgical results, when available. RESULTS: Of the 202 patients found to have carcinoma, the carcinoma was detected with directed biopsy in 145 patients (72%). One hundred twenty (71%) of 169 carcinomas were detected with random biopsy when that procedure was performed. Random biopsies were the only method of diagnosing 57 (28%) of the 202 carcinomas, increasing the yield by 39%. CONCLUSION: Yield of carcinoma on transrectal sonographically guided biopsies increases significantly when segmental random biopsies are performed. Transrectal sonographically guided biopsies should include cores through hypoechoic lesions that are suggestive of carcinoma and bilateral segmental random biopsies.

MRI appearances of an ectopic pituitary adenoma: case report and review of the literature.

MR images of an ectopic pituitary adenoma have been published in only a single case, a suprasellar mass. We present a patient with Cushing's disease in whom MRI revealed a pituitary adenoma within the sphenoid sinus. Radiologic characteristics of ectopic pituitary adenomas are reviewed, with emphasis on MRI, which demonstrates a soft tissue mass, isointense with gray matter on T1-weighted images, which enhances in a heterogeneous manner.