Staged Hybrid Repair of an Intrathoracic Subclavian Artery Aneurysm Associated with a Long Segment Dissection.

Intrathoracic subclavian artery aneurysms (ISAAs) are infrequently seen in clinical practice. We report the repair of a left ISAA associated with a long segment dissection from the ostia extending to the axillary artery. A hybrid approach was used. Carotid-to-axillary bypass using a reversed greater saphenous vein was first performed, followed by coverage of the origin of the subclavian artery using a thoracic stent graft. Finally, percutaneous access of the radial artery with coil embolization was performed to successfully thrombose the ISAA.

Günther Tulip and Celect IVC filters in multiple-trauma patients.

PURPOSE: To evaluate results with the retrievable Günther Tulip (GT) and Celect inferior vena cava filters (IVCFs) placed at the intensive care unit (ICU) bedside under "real-time" intravascular ultrasound (IVUS) guidance in multiple-trauma patients. METHODS: Between December 2004 and December 2008, 187 multiple-trauma patients (109 men; mean age 44+/-2 years, range 17-71) with contraindications to low-dose anticoagulation therapy or sequential compression devices had Günther Tulip (n = 97) or Celect (n = 90) retrievable IVCFs placed under real-time IVUS guidance. Günther Tulip filters were inserted using a "double-puncture" technique. The Celect IVCFs were placed with a simplified single-puncture technique in which the filter introducer sheath was advanced until the radiopaque tip "covered" the IVUS image of the renal vein, indicating that the filter sheath was in position for filter deployment. The 2 filter groups were compared on the endpoints of technical implantation success, retrievability, prevention of PE, and procedure-related deep vein thrombosis (DVT). RESULTS: As verified by abdominal radiography, 93.1% (174/187) of IVCFs were placed without complications; 6 IVCFs (all GT; p = 0.03 versus Celect) were misplaced in the iliac vein but uneventfully retrieved and replaced in the IVC within 24 hours. Two insertion site femoral vein DVTs (both in the dual puncture group; p>0.2) and 5 groin hematomas occurred during follow-up. GT filters were in place a mean of 107 days and Celect 97 days. In this time, 2 pulmonary embolisms occurred (1 in each group; p>0.2). Of the 115 filters scheduled for retrieval (50 Günther Tulip, 65 Celect), 33 (23 Günther Tulip, 10 Celect) could not be retrieved (p = 0.0004). Vena cavography identified filter tilting (>20 degrees ) in 21 cases (15 GT, 6 Celect), while 12 filters (8 GT, 4 Celect) had extended indwell times (mean 187 days) and excessive tissue ingrowth covering the retrieval hook. Subjectively, the Celect filters were clinically "easier" to retrieve; they also had fewer cases of significant tilt (>20%) than the GT filters, but the difference was not statistically significant. CONCLUSION: GT and Celect IVCFs placed at the ICU bedside under IVUS guidance in multiple-trauma patients was simple, safe, and avoided transporting critically ill patients out of the ICU. Further investigation of the single sheath IVUS technique and the role of retrievable IVCFs in multi-trauma patients is warranted.

Endovascular repair of traumatic thoracic aortic disruptions with "stacked" abdominal endograft extension cuffs.

OBJECTIVE: Endovascular stent graft repair of a traumatic thoracic aortic disruption (TTAD) is rapidly becoming an accepted alternative to open surgical repair. The use of currently approved thoracic stent grafts especially in younger patients with small, "steep," tapered aortas, remains a concern due to the acute thoracic endograft collapse and enfolding. The objective of this study, the largest report to date, was to evaluate the mid-term results of TTAD treated with abdominal aortic "stacked" extension cuffs, with follow-up extending to 41 months. METHODS: Thirty-one patients with multi-system trauma (age range, 15 to 61; mean 31.4 years) were seen after motor vehicle accidents between January 1, 2003 and July 1, 2007. Chest x-ray findings warranted thoracic CT scans, which revealed disruptions of the thoracic aorta. Intra-operative arteriograms in all patients and intravascular ultrasound (IVUS) (n = 17) delineated the extent of the aortic injuries. The aortic length from the subclavian artery to the injury averaged 2.5 cm (range, 1.5 to 4.0 cm). The repairs were performed with Gore (W.L. Gore & Associates, Flagstaff, Ariz) (n = 15), Aneuryx (Medtronic, Santa Rosa, Calif) (n = 15), and Zenith (Cook, Inc., Bloomington, Ind) (n = 1) Aortic Extension Cuffs. A femoral artery approach was used in 27 patients and a supra-inguinal retroperitoneal iliac approach in four. All patients underwent thoracic CT scans during follow-up. RESULTS: In all patients, the stent-graft cuffs successfully excluded the TTAD: 21 patients had 2 cuffs, 9 had 3 cuffs, and 1 had 4 cuffs. The aorta adjacent to the injury mean diameter was 18.5 mm (range, 17-24 mm). No subclavian arteries were covered. Two patients required an additional cuff for exclusion of the Type I endoleaks at the distal attachment site within 6 weeks of initial endograft repair. There were no procedure-related deaths; 2 patients died of other injuries. At follow-up, extending to 41 months (range, 3 to 41 months), two pseudo-aneurysms occurred which required open operative repair: 1 due to infection (4 months) and a leaking pseudoaneurysm (14 months). A CT scan in all other survivors demonstrated no device-related complications, endoleaks, or cuff migrations. CONCLUSION: Stent-graft repair of TTAD is technically feasible. The technique of "stacked" aortic cuffs provides an acceptable option when urgent therapy is needed, when patients are deemed high-risk for open operative repair, or until thoracic endografts are designed which can safely treat focal, smaller aortic diameter injuries.

The role of CT angiography in the diagnosis of blunt traumatic thoracic aortic disruption and unsuspected carotid artery injury.

We have replaced aortography and open thoracic surgery to diagnose and treat blunt traumatic thoracic aortic disruption (TTAD) in favor of CT angiography (CTA) and endovascular repair. The purpose of this study is to review our experience with the management and outcomes of TTAD and associated carotid artery injuries. In January 2003, we initiated a protocol that used CTA to evaluate all patients with suspected TTAD from blunt trauma. When TTAD was diagnosed, patients were managed by endovascular repair using abdominal aortic extension cuffs. Twenty-nine patients with TTAD were managed by endovascular repair. In all patients, abdominal endograft extension cuffs successfully excluded the traumatic disruptions. Six (21%) of these patients had concomitant, unsuspected carotid artery injury diagnosed by CTA. One patient had bilateral carotid artery dissections, sustained irreversible brain injury, and died. Four patients with common carotid dissections were successfully treated by anticoagulation and made uneventful recoveries. One patient with a common carotid-innominate artery dissection and pseudoaneurysm underwent endovascular repair. This study indicates that CTA and endovascular repair provide accurate diagnostic and therapeutic results in the management of blunt TTAD. Furthermore, CTA should include arch and cervical views to detect an unsuspected, concomitant carotid artery injury.

Replacing damaged myocardium.

Heart failure survival after diagnosis has barely changed for more than half a century. Recently, investigation has focused on differentiation of stem cells in vitro and their delivery for use in vivo as replacement cardiac contractile elements. Here we report preliminary results using mesenchymal stem cells partially differentiated to a cardiac lineage in vitro. When delivered to the canine heart on an extracellular matrix patch to replace a full-thickness ventricular defect in vivo, they improve regional mechanical function. The delivered cells were also tracked, and some became myocytes with mature sarcomeres.

Accuracy and reproducibility of a subpixel extended phase correlation method to determine micron level displacements in the heart.

Future treatment of heart disease may involve local perturbations of mechanical function, such as intramyocardial injections of angiogenic growth factors or progenitor cells. This necessitates an accurate measurement technique to determine regional heart function. We have previously developed a method to determine regional heart function using a phase correlation algorithm. However, in determining regional function over a single heartbeat it is necessary to sum displacements between many images. We have therefore incorporated a subpixel algorithm that models the result of phase correlation as a sinc function in order to increase the accuracy of our technique. This method, which we have named high density mapping (HDM), determines the subpixel displacement of 64 x 64 pixel regions from images of the heart. To determine the accuracy and precision of the technique, a high contrast image of a heart was digitally shifted 1, 2 or 3 pixels. The original and shifted images were then downsampled four times resulting in 0.25, 0.50 or 0.75 pixel shifts between the original and shifted images. The average accuracy of HDM in the digitally shifted images was 0.06 pixels, with a precision of 0.08 pixels. Effectiveness of HDM in characterization of deformation was also assessed in digitally stretched images. Error in quantification of strain was found to be less than 3.5% of the calculated strain. In an additional set of experiments, in which accuracy was determined using physical motion instead of digital shifting and downsampling, a speckle pattern was displaced by known distances using a micromanipulator, such that the displacement between the captured images was 0.5 pixels. These data demonstrated an accuracy of 0.09 pixels and a precision of 0.02 pixels. Finally, as HDM is used to determine the regional stroke work index (RSW) in beating hearts, the repeatability of using this method to compute RSW was assessed. RSW, the integral of intraventricular pressure with respect to unitless regional area, where end diastolic area was normalized to unity, was assessed in consecutive beats from four different hearts. The average standard deviation of RSW was 0.098 mmHg. Uncertainty analysis determined the maximum error of RSW to be +/-0.41 mmHg, approximately two-thirds of the measured biologic variability. These data demonstrate the ability of HDM to accurately and reproducibly measure displacement and regional function in the beating heart.

Tissue-engineered myocardial patch derived from extracellular matrix provides regional mechanical function.

BACKGROUND: Extracellular matrix (ECM), a tissue-engineered scaffold, recently demonstrated cardiomyocyte population after myocardial implantation. Surgical restoration of myocardium frequently uses Dacron as a myocardial patch. We hypothesized that an ECM-derived myocardial patch would provide a mechanical benefit not seen with Dacron. METHODS AND RESULTS: Using a canine model, a full thickness defect in the right ventricle was repaired with either Dacron or ECM. A third group had no surgery and determined baseline RV function. Eight weeks later, global systolic function was assessed by the preload recruitable stroke work relationship. Regional systolic function was measured by systolic area contraction (SAC), calculated by high density mechanical mapping. Tau was used to assess global diastolic function. Recoil rate and diastolic shear were used as measures of regional diastolic function. After functional data acquisition, tissue was fixed for histological evaluation. Global systolic and diastolic functions were similar at baseline and after ECM and Dacron implantation. Regional systolic function was greater in the ECM group compared with the Dacron group (SAC: 4.1+/-0.9% versus -1.8+/-1.1, P<0.05). Regional diastolic function was also greater in the ECM group (recoil rate (degrees sec(-1)): -44+/-7 versus -17+/-2, ECM versus Dacron; P<0.05). Immunohistochemical analysis revealed cardiomyocytes in the ECM implant region, a finding not seen with Dacron. CONCLUSIONS: At 8 weeks, an ECM-derived tissue-engineered myocardial patch provides regional mechanical function, likely related to cardiomyocyte population. These results are in sharp contrast to Dacron, a commonly used myocardial patch.

The use of extracellular matrix as an inductive scaffold for the partial replacement of functional myocardium.

Regenerative medicine approaches for the treatment of damaged or missing myocardial tissue include cell-based therapies, scaffold-based therapies, and/or the use of specific growth factors and cytokines. The present study evaluated the ability of extracellular matrix (ECM) derived from porcine urinary bladder to serve as an inductive scaffold for myocardial repair. ECM scaffolds have been shown to support constructive remodeling of other tissue types including the lower urinary tract, the dermis, the esophagus, and dura mater by mechanisms that include the recruitment of bone marrow-derived progenitor cells, angiogenesis, and the generation of bioactive molecules that result from degradation of the ECM. ECM derived from the urinary bladder matrix, identified as UBM, was configured as a single layer sheet and used as a biologic scaffold for a surgically created 2 cm2 full-thickness defect in the right ventricular free wall. Sixteen dogs were divided into two equal groups of eight each. The defect in one group was repaired with a UBM scaffold and the defect in the second group was repaired with a Dacron patch. Each group was divided into two equal subgroups (n = 4), one of which was sacrificed 15 min after surgical repair and the other of which was sacrificed after 8 weeks. Global right ventricular contractility was similar in all four subgroups groups at the time of sacrifice. However, 8 weeks after implantation the UBM-treated defect area showed significantly greater (p < 0.05) regional systolic contraction compared to the myocardial defects repaired with by Dacron (3.3 +/- 1.3% vs. -1.8 +/- 1.1%; respectively). Unlike the Dacron-repaired region, the UBM-repaired region showed an increase in systolic contraction over the 8-week implantation period (-4.2 +/- 1.7% at the time of implantation vs. 3.3 +/- 1.3% at 8 weeks). Histological analysis showed the expected fibrotic reaction surrounding the embedded Dacron material with no evidence for myocardial regeneration. Histologic examination of the UBM scaffold site showed cardiomyocytes accounting for approximately 30% of the remodeled tissue. The cardiomyocytes were arranged in an apparently randomly dispersed pattern throughout the entire tissue specimen and stained positive for alpha- sarcomeric actinin and Connexin 43. The thickness of the UBM graft site increased greatly from the time of implantation to the 8-week sacrifice time point when it was approximately the thickness of the normal right ventricular wall. Histologic examination suggested complete degradation of the originally implanted ECM scaffold and replacement by host tissues. We conclude that UBM facilitates a constructive remodeling of myocardial tissue when used as replacement scaffold for excisional defects.

Use of the Angiojet catheter to remove plaque outside a neuroprotection filter during carotid artery stenting.

Carotid protection devices (CPD) during carotid artery stenting reduce the risk of cerebral embolization. The presence of debris outside the filter presents a problem as the material may be plaque or thrombus. We report a case that required the use of the Angiojet catheter to remove debris outside the CPD.

Increased myocyte content and mechanical function within a tissue-engineered myocardial patch following implantation.

During the past few years, studies involving the implantation of stem cells, chemical factors, and scaffolds have demonstrated the ability to augment the mammalian heart's native regenerative capacity. Scaffolds comprised of extracellular matrix (ECM) have been used to repair myocardial defects. These scaffolds become populated with myocytes and provide regional contractile function, but quantification of the myocyte population has not yet been conducted. The purpose of this study was to quantitate the myocyte content within the ECM bioscaffold and to correlate this cell population with the regional mechanical function over time. Xenogenic ECM scaffolds derived from porcine urinary bladder were implanted into a full-thickness, surgically induced, right ventricular-free wall defect in a dog model. Zero, 2, and 8 weeks following implantation, regional function and myocyte content were determined in each patch region. Regional function did not significantly increase from 0 to 2 weeks. At 8 weeks, however, regional stroke work increased to 3.7 +/- 0.7% and systolic contraction increased to 4.4 +/- 1.2%. The myocyte content also significantly increased during that period generating a linear relationship between regional function and myocyte content. In conclusion, ECM used as a myocardial patch increases both the regional function and the myocyte content over time. The mechanical function generated in the patch region is correlated with the quantity of local tissue myocytes.

Enhanced recovery of mechanical function in the canine heart by seeding an extracellular matrix patch with mesenchymal stem cells committed to a cardiac lineage.

The need to regenerate tissue is paramount, especially for the heart that lacks the ability to regenerate after injury. The urinary bladder extracellular matrix (ECM), when used to repair a right ventricular defect, successfully regenerated some mechanical function. The objective of the current study was to determine whether the regenerative effect of ECM could be improved by seeding the patch with human mesenchymal stem cells (hMSCs) enhanced to differentiate down a cardiac linage. hMSCs were used to form three-dimensional spheroids. The expression of cardiac proteins was determined in cells exposed to the spheroid formation and compared with nonmanipulated hMSCs. To determine whether functional calcium channels were present, the cells were patch clamped. To evaluate the ability of these cells to regenerate mechanical function, the spheroids were seeded on ECM and then implanted into the canine heart to repair a full-thickness right ventricular defect. As a result, many of the cells spreading from the spheroids expressed cardiac-specific proteins, including sarcomeric alpha-actinin, cardiotin, and atrial natriuretic peptide, as well as the cell cycle markers cyclin D1 and proliferating cell nuclear antigen. A calcium current similar in amplitude to that of ventricular myocytes was present in 16% of the cells. The cardiogenic cell-seeded scaffolds increased the regional mechanical function in the canine heart compared with the unmanipulated hMSC-seeded scaffolds. In addition, the cells prelabeled with fluorescent markers demonstrated myocyte-specific actinin staining with sarcomere spacing similar to that of normal myocytes. In conclusion, the spheroid-derived cells express cardiac-specific proteins and demonstrate a calcium current similar to adult ventricular myocytes. When these cells are implanted into the canine heart, some of these cells appear striated and mechanical function is improved compared with the unmanipulated hMSCs. Further investigation will be required to determine whether the increased mechanical function is due to a differentiation of the cardiogenic cells to myocytes or to other effects.