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Biomedical subjects

Michael D Dake

Publications and source records attributed to Michael D Dake.

At least 19 recordsLinked to original sources
PubMed2006

Massive pulmonary embolus with hemodynamic compromise: therapeutic options.

Recent advances in pharmacotherapeutics and interventional techniques have resulted in resurgence in interest regarding the optimal means of management of hemodynamically significant pulmonary embolic disease. However, these various techniques have many associated disadvantages, and it is of paramount importance that the responsible physician has a detailed understanding of each of these so that the appropriate intervention be requested and performed. By way of background discussion and relevant cases in point, we consider each of these management options in turn, with particular reference to the advantages, disadvantages, and application of each.

Anticoagulants↗
PubMed2006

Stent-graft repair of an aortic rupture caused by invasive hemangiopericytoma.

We describe a patient with a history of hemangiopericytoma, who had hemoptysis develop due to a pseudoaneurysm of the thoracic aorta from an intrathoracic metastasis. Stent-graft repair successfully excluded the aneurysm from the aorta. Transesophageal echocardiography showed to be an important guide for correct placement of the device.

Aneurysm, False↗
PubMed2006

Will stent-graft repair emerge as treatment of choice for acute type B dissection?

Endovascular stent grafts are now accepted globally and approved by the US Food and Drug Administration as an alternative to open surgical repair for patients with descending thoracic aortic aneurysm. However, as opposed to the abdominal aorta, application of this technology to manage thoracic aortic disease is not limited to degenerative aneurysms. In fact, international registries and surveys estimate that only 60% of the thoracic cases managed currently with stent-graft placement are aneurysms. The remainder of this experience includes acute dissection, chronic dissection, traumatic aortic injury, penetrating ulcer, intramural hematoma, aortic fistula, anastomotic pseudoaneurysm, and an embolizing lesion. In this regard, it is important to keep in mind that the present devices used in these nonaneurysmal applications are not designed to address the unique anatomical and pathological features that these lesions present. Consequently, in the future, it is possible that we will see stent-graft designs that focus specifically on the challenges of some of the nonaneurysmal thoracic aortic pathologies.

Aged↗
PubMed2006

Molecular imaging: a primer for interventionalists and imagers.

The characterization of human diseases by their underlying molecular and genomic aberrations has been the hallmark of molecular medicine. From this, molecular imaging has emerged as a potentially revolutionary discipline that aims to visually characterize normal and pathologic processes at the cellular and molecular levels within the milieu of living organisms. Molecular imaging holds promise to provide earlier and more precise disease diagnosis, improved disease characterization, and timely assessment of therapeutic response. This primer is intended to provide a broad overview of molecular imaging with specific focus on future clinical applications relevant to interventional radiology.

Animals↗
PubMed2006

Thoracic aortic endografting is the treatment of choice for elderly patients with thoracic aortic disease.

OBJECTIVE: To assess the effect of age on outcomes following thoracic aortic endografting. SUMMARY BACKGROUND DATA: Endograft therapy for thoracic aortic disease is rapidly evolving. This therapy is less invasive, and elderly patients with significant medical comorbidities are more frequently referred for endografting. We hypothesized that elderly patients over the age of 75 have worse outcomes after thoracic endografting than patients under the age of 75. METHODS: We retrospectively reviewed the charts of the first 42 patients who underwent endografting for thoracic aortic pathology. Charts were reviewed for demographics, comorbid conditions, perioperative complications and death, endoleaks, and results at 3, 6, and 12 months. Preexisting medical conditions were also evaluated to determine if any patient characteristics were associated with adverse outcomes. Perioperative morbidity included cardiac, pulmonary, renal, hemorrhagic, and neurologic (stroke and spinal cord injury) complications. RESULTS: Twenty-four patients were under the age of 75, and 18 patients were 75 or older. Baseline demographics and comorbidities were similar between the 2 groups. There were no differences in operative time, length of stay, perioperative mortality, or the incidence of significant complications between the 2 age groups. Gender, however, was associated with a statistically significant difference between the occurrence of complications, with more women experiencing complications than men (P = 0.026, relative risk = 2.36). One patient (age >75 years) in the entire cohort of 42 (2.4%) suffered a spinal cord injury. At 3 months, endoleaks were more common in the older age group (P = 0.059). CONCLUSION: Endograft therapy for thoracic aortic disease can be performed safely in elderly patients with no significant increase in perioperative morbidity or mortality compared with younger patients. Female gender is associated with a higher likelihood of perioperative complications, regardless of age. The overall incidence of spinal cord injury is very low. Endograft therapy, when anatomically possible, is the treatment of choice for thoracic aortic disease in elderly patients.

Adult↗
PubMed2005

Treatment of hepatic venous outflow obstruction after piggyback liver transplantation.

PURPOSE: To evaluate retrospectively the endovascular management of hepatic venous outflow obstruction after piggyback orthotopic liver transplantation. MATERIALS AND METHODS: The study was performed with the approval and under the guidelines of the institutional review board and complied with the Health Insurance Portability and Accountability Act. Informed consent from patients was not required by the institutional review board for this retrospective study. From 1995 to 2003, 13 patients (eight male, five female), including 12 adults and one adolescent (age range, 14-67 years; median age, 52 years), underwent endovascular treatment of hepatic venous outflow obstruction after piggyback orthotopic liver transplantation. Patients gave informed consent for all procedures. Eleven patients received whole livers, and two received living-related donor right liver lobes. Four underwent repeat piggyback orthotopic liver transplantation prior to intervention. Primary stent placement was performed in 12 patients. One patient refused primary stent placement and chose venoplasty alone, but required a stent 5 months later. Short balloon-expandable stents (mean diameter, 14.6 mm +/- 1.1 [standard deviation]) were used to minimize jailing of branch vessels and to resist recoil. Pre- and post-procedural pressure gradients were measured. Follow-up included venography, cross-sectional imaging, and laboratory tests. The Wilcoxon signed rank test or the sign test was performed to compare pre- and post-procedural pressure gradients, body weights, and laboratory values. RESULTS: Technical success (pressure gradient < or = 3 mm Hg) was achieved in 13 of 13 patients, and clinical success, in 12 of 13. Mean pre- and post-procedural pressure gradients were 13.0 mm Hg +/- 1.4 and 0.8 mm Hg +/- 0.3. Mean interval from transplantation to intervention was 348 days +/- 159. Mean follow-up was 678 days (range, 16-2880 days). Technical success did not result in clinical improvement in one patient. Biopsy demonstrated severe hepatic necrosis, likely from prolonged venous congestion, and the patient required repeat transplantation. Only one patient required reintervention for stent migration, and no other complications occurred. No significant restenosis was encountered after stent placement. CONCLUSION: Hepatic venous outflow obstruction is an uncommon but potentially fatal complication of piggyback orthotopic liver transplantation. Endovascular treatment with balloon-expandable stents is effective, safe, and apparently durable.

Adolescent↗
PubMed2005

Liver tissue engineering at extrahepatic sites in mice as a potential new therapy for genetic liver diseases.

Liver tissue engineering using hepatocyte transplantation has been proposed as an alternative to whole-organ transplantation or liver-directed gene therapy to correct various types of hepatic insufficiency. Hepatocytes are not sustained when transplanted under the kidney capsule of syngeneic mice. However, when we transplanted hepatocytes with the extracellular matrix components extracted from Engelbreth-Holm-Swarm cells, hepatocytes survived for at least 140 days and formed small liver tissues. Liver engineering in hemophilia A mice reconstituted 5% to 10% of normal clotting activity, enough to reduce the bleeding time and have a therapeutic benefit. Conversely, the subcutaneous space did not support the persistent survival of hepatocytes with Engelbreth-Holm-Swarm gel matrix. We hypothesized that establishing a local vascular network at the transplantation site would reduce graft loss. To test this idea, we provided a potent angiogenic agent before hepatocyte transplantation into the subcutaneous space. With this procedure, persistent survival was achieved for the length of the experiment (120 days). To establish that these engineered liver tissues also retained their native regeneration potential in vivo, we induced two different modes of proliferative stimulus to the naive liver and confirmed that hepatocytes within the extrahepatic tissues regenerated with activity similar to that of naive liver. In conclusion, our studies indicate that liver tissues can be engineered and maintained at extrahepatic sites, retain their capacity for regeneration in vivo, and used to successfully treat genetic disorders.

Angiogenic Proteins↗
PubMed2005

MR-guided transjugular intrahepatic portosystemic shunt creation with use of a hybrid radiography/MR system.

PURPOSE: To evaluate the performance of a combined hybrid radiography/magnetic resonance (MR) unit to guide portal vein (PV) puncture during human transjugular intrahepatic portosystemic shunt (TIPS) creation. MATERIALS AND METHODS: Fourteen patients undergoing TIPS creation were studied during standard clinical applications. Patients were anesthetized and then positioned in an open MR unit containing a flat-panel radiographic fluoroscopic unit. With use of a combination of fluoroscopy and MR imaging, the PV was accessed and the TIPS procedure was performed. A noncovered nitinol stent or a covered stent-graft was placed in the TIPS tract. Number of punctures required, total procedure time, fluoroscopy time, procedural success rate, complications, and ultrasonographic and clinical follow-up were recorded. RESULTS: Clinical success was obtained in 13 of 14 patients. In one patient, extrahepatic puncture of the PV occurred, resulting in hemorrhage and requiring placement of a covered stent to control the bleeding. The mean number of punctures required to access the PV was 2.6 +/- 1.7, and the total procedure time was 2.5 hours +/- 0.6. Mean fluoroscopy time was 22.3 minutes +/- 5.5. Results of clinical and ultrasonographic follow-up compare favorably to previously published reports. CONCLUSION: TIPS creation with a combination hybrid radiography/MR unit is feasible and may reduce the number of needle passes required and radiation exposure, with similar overall outcomes compared with studies reported in the literature.

Alloys↗
PubMed2005

Portal hypertensive hemorrhage from a left gastroepiploic vein caput medusa in an adhesed umbilical hernia.

Caput medusa is a frequent incidental finding in patients with portal hypertension that usually represents paraumbilical vein portosystemic collateral vessels draining into body wall systemic veins. A symptomatic caput medusa was seen in a morbidly obese patient after an umbilical hernia repair, which was fed not by the left portal vein but by the left gastroepiploic vein, in a recurrent adhesed umbilical hernia that likely contained herniated omentum. Refractory hemorrhage from this caput medusa was successfully treated by transjugular intrahepatic portosystemic shunt creation and balloon-occluded variceal sclerosis.

Hemorrhage↗
PubMed2005

Multi-institutional pivotal trial of the Zenith TX2 thoracic aortic stent-graft for treatment of descending thoracic aortic aneurysms: clinical study design.

Despite significant improvements in surgical techniques and perioperative management, the repair of descending thoracic aortic aneurysms remains a challenge with the potential for substantial morbidity and mortality. Over the past several years, buoyed by the technical success of endovascular repair of infrarenal abdominal aortic aneurysms, several case series reports of endovascular stent-graft placement for descending thoracic aortic aneurysms have demonstrated the potential safety and efficacy of this treatment modality. Several single-institution studies have documented promising results with these devices, but without controlled clinical trials, the data are insufficient to determine if thoracic aortic endografts provide equivalent or improved outcomes compared with standard open repair. We describe a study design of an ongoing prospective, nonrandomized, multi-institutional, investigational device exemption phase II pivotal clinical trial investigating the safety and effectiveness of the Zenith TX2 thoracic aortic endovascular graft in the elective treatment of patients with descending thoracic aortic aneurysms.

Aortic Aneurysm, Thoracic↗
PubMed2005

Directed migration of smooth muscle cells to engineer plaque-resistant vein grafts.

PURPOSE: To test the hypothesis that controlled perivascular release of tissue plasminogen activator (tPA) can generate cleaved extracellular matrix (ECM) chemotactic gradients to guide the migration of vascular smooth muscle cells (SMCs) away from the lumen, thereby limiting neointima formation. METHODS: This hypothesis was tested in rabbit models in which the perivascular surface of vein bypass grafts was treated with microspheres releasing tPA (MS-tPA), microspheres containing no drug (MS-blank), or phosphate buffered saline (PBS). Vein graft segments harvested after 7 days were then evaluated for elastin content, proliferating SMCs, intima-to-media (I/M) ratio, and inflammation; late impact on neointima formation was also examined. RESULTS: The 7-day results demonstrated cleaved elastin gradients and proliferating SMCs that assumed a more peripheral distribution in the MS-tPA group than MS-blank and PBS controls (p<0.05). At 28 days, vein grafts treated with MS-tPA showed a mean I/M ratio (0.35+/-0.04) that was 63.5% lower than PBS controls (0.96+/-0.07, p<0.005) and 43.5% lower than MS-blank specimens (0.62+/-0.08, p<0.05). CONCLUSIONS: Perivascular release of tPA modifies ECM gradients, directionally guides SMC migration away from the lumen, and limits neointima formation.

Analysis of Variance↗
PubMed2005

Multiple HIV-related aneurysms: open and endovascular treatment.

PURPOSE: To report successful endovascular repair of thoracic aortic aneurysms in 2 patients with human immunodeficiency virus (HIV). CASE REPORTS: Thoracic and abdominal aortic aneurysms (AAA) were found in a 60-year-old woman 1 year after she was diagnosed with HIV. Because of pain and risk of rupture, the AAA was repaired with conventional open techniques in February 1997, while the thoracic aneurysm was excluded in a staged procedure using a homemade endograft delivered through a 10-mm conduit sewn to the aortic tube graft. Two months later, new aneurysms were found in the superficial femoral arteries bilaterally; both were excised and replaced with vein grafts. After 7 years, the patient is well and no longer takes antiretroviral medication. Surveillance imaging shows continued patency of the stent-graft without evidence of leak or migration. In a more contemporary case, a 46-year-old man was found to have 5 focal aneurysms in the aorta; the most proximal descending thoracic aneurysm increased 2 cm in 2 weeks. The two thoracic aneurysms were successfully excluded using 2 Excluder stent-grafts. At 7 months, he was doing well, and the aneurysm had shrunk 11 mm. CONCLUSIONS: Endovascular and open treatment of HIV-related aneurysms is possible, with excellent long-term results. Patients with long-life expectancy should be treated according to the same guidelines as patients without HIV.

Aneurysm, Infected↗
PubMed2004

Direct medical costs attributable to acute myocardial infarction and ischemic stroke in cohorts with atherosclerotic conditions.

BACKGROUND: The cost of acute ischemic events in persons with established atherosclerotic conditions is unknown. METHODS: The direct medical costs attributable to secondary acute myocardial infarction (AMI) or ischemic stroke among persons with established atherosclerotic conditions were estimated from 1995-1998 data on 1,143 patients enrolled in US managed care plans. RESULTS: The average 180-day costs attributable to secondary AMI or stroke were estimated as USD 19,056 in the AMI cohort having a private insurance (commercial; n = 344), USD 16,845 in the AMI cohort having government insurance (Medicare, age >/=65 years; n = 200), USD 10,267 for stroke commercial (n = 108), USD 16,280 for stroke Medicare (n = 113), USD 15,224 for peripheral arterial disease commercial (n = 170), and USD 15,182 for peripheral arterial disease Medicare (n = 208). CONCLUSION: These estimates can be used to study the cost-effectiveness of interventions proven to reduce these secondary events.

Aged↗
PubMed2004

Chronic traumatic aneurysms of the descending thoracic aorta: mid-term results of endovascular repair using first and second-generation stent-grafts.

OBJECTIVE: Endovascular stent-graft repair holds promise for treating traumatic injuries of the descending thoracic aorta. The durability of this approach, however, remains unknown. The objective is to evaluate the mid-term results of stent-graft repair of chronic traumatic aneurysms of the descending thoracic aorta. METHODS: Between 1993 and 2000, endovascular repair of the descending thoracic aorta with first (custom-fabricated) and second-generation (commercial) stent-grafts was performed in 15 patients (mean age 54+/-13 years) at an average of 18+/-14 years after the injury. Because of comorbidities, 4 patients (27%) were judged not to be reasonable surgical candidates for conventional open surgical approach. Follow-up was 100% complete and averaged 55+/-29 months. RESULTS: Stent-graft deployment was successful in all without need for surgical conversion. One patient died early postoperatively. No neurologic complications occurred. Two patients had a primary endoleak, one of them was successfully treated before discharge. Actuarial survival estimates at 1 and 6 years were 93+/-6% and 85+/-10%. Actuarial freedom from reintervention on the descending thoracic aorta was 93+/-6% and 70+/-15% at 1 and 6 years, respectively. Actuarial freedom from treatment failure (a conservative, all-encompassing performance indicator including endoleak, device mechanical fault, reintervention, late aortic-related death, or sudden, unexplained late death) at 1 and 6 years was 87+/-8% and 51+/-15%. CONCLUSIONS: Stent-grafting is safe in selected patients with chronic traumatic aneurysms and associated with satisfactory-but not optimal-mid-term durability. Serial follow-up surveillance imaging is mandatory to detect late stent-graft complications. Younger, good risk patients should be offered conventional open operation, reserving stent-grafting for those who are at prohibitive operative risk or who have limited life expectancy.

Adult↗