Transmural Defects Research Articles

Open-pore film drainage (OFD): a new multipurpose tool for endoscopic negative pressure therapy (ENPT)

Background and study aims Endoscopic negative pressure therapy (ENPT) has been developed to treat gastrointestinal leakages. Up to now, ENPT has usually been performed with open-pore polyurethane foam drains (OPD). A big disadvantage of the OPDs is their large diameter. We have developed a new, small-bore open-pore film drainage (OFD). Herein we report our first experience in a case series of 16 patients. Patients and methods OFD is constructed with a drainage tube and a very thin double-layered open-pore drainage film (Suprasorb CNP, Drainage Film, Lohmann & Rauscher International, Germany). The distal end of the tube is wrapped with only one layer of film. OFD is placed into the gastrointestinal leakage site with common endoscopic techniques. The tube is connected to an electronic vacuum device and continuous negative pressure of –125 mmHg applied. Results From 2013 to 2016, 16 patients were treated with the new OFD device. In 10 patients, transmural intestinal defects (4 esophageal, 4 rectum/colon, 1 duodenal, 1 pancreatic cyst) were closed with ENPT in median time of 12 days (range 3 – 34 days). Five of the 10 patients were treated solely with OFD devices. In five patients ENPT started with ODP and changed to OFD when the cavity was shrunken to a channel with a small opening. In four patients postoperative gastric reflux was eliminated for 5 to 16 days. Conclusions Small-bore OFD opens up promising new treatment options within ENPT. OFD can be used in endoscopic closure management of intestinal leakages in the upper and lower gastrointestinal tract. Gastric reflux can be eliminated in an active manner. OFD can be inserted nasally. OFD may be an adequate substitute for OPD, especially when placement of the larger OPD is difficult.

Endoscopic Management of Transmural Defects, Including Leaks, Perforations, and Fistulae

Transmural defects of the gastrointestinal tract can be classified into 3 distinct entities-leak, perforation, and fistula. Each arises from different mechanisms and is managed accordingly. Leaks occur most often after surgery, while perforations occur most often after flexible endoscopic maneuvers. Fistulae arise from a variety of mechanisms, such as an evolution from surgical leaks, as well as from specific disease states. Endoscopic management plays a vital role in the treatment of transmural defects as long as the region of interest can be accessed with the appropriate endoscopic accessories. Endoscopic approaches can be broadly classified into those that provide closure andthose that provide diversion of luminal contents. Withadvances in technology, a myriad of devices and accessories are available that allow a tailored approach. Endoscopic approaches to leaks, perforations, and fistulae are discussed in this review.

MRI-assisted dual motion correction for myocardial perfusion defect detection in PET imaging.

Myocardial perfusion (MP) PET imaging is a powerful tool in risk assessment and stratification of patients with coronary artery disease. Involuntary organ motion degrades cardiac PET image resolution, while respiratory and/or cardiac gating to freeze the motion leads to noisier reconstructed images due to reduced counts in the gated frames. In this work, we propose an MRI-assisted dual motion correction method to compensate for respiratory and cardiac motion in MP PET data and study the impact of dual motion correction on MP defect detection using systematically designed experiments. The proposed dual motion correction method addresses the respiratory motion before correcting the cardiac motion among the respiratory motion corrected cardiac gates. The respiratory motion is estimated from the respiratory-gated only PET images and compensated within a 4D motion-incorporated image reconstruction algorithm. The cardiac motion is then corrected using the motion vector fields estimated from the corresponding cardiac-gated MR images. To evaluate the proposed method, we performed experiments using the standard XCAT phantom and two individual-specific volunteer XCAT phantoms. For each of the three phantoms, we simulated four dual-gated Rb-82 MP PET imaging datasets, one with normal perfusion and the other three with 50% nontransmural, 75% nontransmural, and transmural regionally reduced perfusion. The corresponding cardiac-gated MR images were simulated by the SIMRI simulator, with the sequence specified to be 3D T1-weighted as used in a protocol of a clinical PET/MRI scanner. We quantitatively evaluated the reconstructed images with no motion correction, only respiratory motion correction and dual motion correction, in terms of the myocardium to blood pool contrast and the trade-off between the noise and the normal to defect contrast. Using the channelized Hotelling observer, we performed receiver operating characteristic analysis for the task of detecting perfusion abnormalities with various myocardial coverages. Compared with no motion correction, the respiratory motion correction was demonstrated to improve the myocardium to blood pool contrast as well as the trade-off between the noise and the normal to defect contrast, on top of which the cardiac motion correction furthered the improvement. In the task of detecting regional perfusion defects, transmural or different levels of nontransmural, the respiratory motion correction significantly increased the defect detectability compared with no motion correction. Additionally, the respiratory and cardiac motion correction significantly improved the defect detection compared with the respiratory motion correction alone. Furthermore, the separability of the transmural and nontransmural defects was also improved by the proposed MRI assisted dual motion correction method. The proposed dual respiratory and cardiac motion correction technique improves the accuracy of PET quantification and MP defect detection and classification, which shows its promise for clinical applications especially in cardiac PET/MR imaging.

Impact of respiratory motion correction on SPECT myocardial perfusion imaging using a mechanically moving phantom assembly with variable cardiac defects

BackgroundThe aim of this study was to determine the impact of respiratory motion correction on SPECT MPI and on defect detection using a phantom assembly. MethodsSPECT/CT data were acquired using an anthropomorphic phantom with inflatable lungs and with an ECG beating and moving cardiac compartment. The heart motion followed the respiratory pattern in the cranio-caudal direction to simulate normal or deep breathing. Small or large transmural defects were inserted into the myocardial wall of the left ventricle. SPECT/CT images were acquired for each of the four respiratory phases, from exhale to inhale. A respiratory motion correction was applied using an image-based method with transformation parameters derived from the SPECT data by a non-rigid registration algorithm. A report on defect detection from two physicians and a quantitative analysis on MPI data were performed before and after applying motion correction. ResultsRespiratory motion correction eliminated artifacts present in the images, resulting in a uniform uptake and reduction of motion blurring, especially in the inferior and anterior regions of the LV myocardial walls. The physicians’ report after motion correction showed that images were corrected for motion. ConclusionsA combination of motion correction with attenuation correction reduces artifacts in SPECT MPI. AC-SPECT images with and without motion correction should be simultaneously inspected to report on small defects.

Quantitative myocardial perfusion PET parametric imaging at the voxel-level

Quantitative myocardial perfusion (MP) PET has the potential to enhance detection of early stages of atherosclerosis or microvascular dysfunction, characterization of flow-limiting effects of coronary artery disease (CAD), and identification of balanced reduction of flow due to multivessel stenosis. We aim to enable quantitative MP-PET at the individual voxel level, which has the potential to allow enhanced visualization and quantification of myocardial blood flow (MBF) and flow reserve (MFR) as computed from uptake parametric images. This framework is especially challenging for the 82Rb radiotracer. The short half-life enables fast serial imaging and high patient throughput; yet, the acquired dynamic PET images suffer from high noise-levels introducing large variability in uptake parametric images and, therefore, in the estimates of MBF and MFR. Robust estimation requires substantial post-smoothing of noisy data, degrading valuable functional information of physiological and pathological importance. We present a feasible and robust approach to generate parametric images at the voxel-level that substantially reduces noise without significant loss of spatial resolution. The proposed methodology, denoted physiological clustering, makes use of the functional similarity of voxels to penalize deviation of voxel kinetics from physiological partners. The results were validated using extensive simulations (with transmural and non-transmural perfusion defects) and clinical studies. Compared to post-smoothing, physiological clustering depicted enhanced quantitative noise versus bias performance as well as superior recovery of perfusion defects (as quantified by CNR) with minimal increase in bias. Overall, parametric images obtained from the proposed methodology were robust in the presence of high-noise levels as manifested in the voxel time-activity-curves.

Reconstruction of a large through-and-through defect of the nasal tip using a modified auricular composite graft.

The nose is the most important part in the aesthetic appearance of the face because of its central position. It is difficult to reconstruct a large through-and through defect of the nasal tip among nasal defect deformities because of its unique individual characteristics. In this article, we describe the successful use of a modified auricular composite graft (larger than traditional size) for the reconstruction of large transmural defects of the nasal tip. We retrospectively examined 4 patients diagnosed with a defect of the nasal tip between 2009 and 2011; in our patients, the size of the defect was between 2 × 1 cm and 2.5 × 1 cm. All of them received the same surgical method. The patients were followed up from 3 to 12 months. After the operation, the patients had hyperbaric oxygen therapy for 7 days to improve graft oxygenation. All patients attained relatively full-bodied and smooth nasal contours as well as inconspicuous scars and found their reconstructed nasal tip and alae to be aesthetically satisfactory. Two patients experienced partial epidermal necrosis of the transplanted auricular composite grafts, which was recovered by saline-moistened gauze dressing. All the auricular composite tissue flaps had color change, and the contours of donor ears had little change.

Dynamic Myocardial CT Perfusion Imaging for Evaluation of Myocardial Ischemia as Determined by MR Imaging

The aim of this study was to determine the feasibility of computed tomography (CT)-based dynamic myocardial perfusion imaging for the assessment of myocardial ischemia and infarction compared with cardiac magnetic resonance (CMR). Sequential myocardial CT perfusion imaging has emerged as a novel imaging technique for the assessment of myocardial hypoperfusion. We prospectively enrolled subjects with known coronary artery disease who underwent adenosine-mediated stress dynamic dual-source CT (100 kV, 320 mAs/rot) and CMR (3-T). Estimated myocardial blood flow (eMBF) and estimated myocardial blood volume (eMBV) were derived from CT images, using a model-based parametric deconvolution technique. The values were independently related to perfusion defects (ischemic and/or infarcted myocardial segments) as visually assessed during rest/stress and late gadolinium enhancement CMR. Conventional measures of diagnostic accuracy and differences in eMBF/eMBV were determined. Of 38 enrolled subjects, 31 (mean age 70.4 ± 9.3 years; 77% men) completed both CT and CMR protocols. The prevalence of ischemic and infarcted myocardial segments detected by CMR was moderate (11.6%, n= 56 and 12.6%, n= 61, respectively, of 484 analyzed segments, with 8.4% being transmural). The diagnostic accuracy of CT for the detection of any perfusion defect was good (eMBF threshold, 88 ml/mg/min; sensitivity, 77.8% [95% confidence interval (CI): 69% to 85%]; negative predictive value, 91.3% [95% CI: 86% to 94%]) with moderate positive predictive value (50.6% [95% CI: 43% to 58%] and specificity (75.41% [95% CI: 70% to 79%]). Higher diagnostic accuracy was observed for transmural perfusion defects (sensitivity 87.8%; 95% CI: 74% to 96%) and infarcted segments (sensitivity 85.3%; 95% CI: 74% to 93%). Although eMBF in high-quality examinations was lower but not different between ischemic and infarcted segments (72.3 ± 18.7 ml/100 ml/min vs. 73.1 ± 31.9 ml/100 ml/min, respectively, p> 0.05), eMBV was significantly lower in infarcted segments compared with ischemic segments (11.3 ± 3.3 ml/100 ml vs. 18.4 ± 2.8 ml/100 ml, respectively; p < 0.01). Compared with CMR, dynamic stress CT provides good diagnostic accuracy for the detection of myocardial perfusion defects and may differentiate ischemic and infarcted myocardium.

Diagnostic sensitivity of SPECT myocardial perfusion imaging using a pumping cardiac phantom with inserted variable defects

BackgroundThe diagnostic sensitivity of various SPECT MPI procedures was assessed using a pumping cardiac phantom with variable defects inserted in the myocardial wall of the left ventricle. Methods and ResultsA diagnostic evaluation of 142 myocardial defects was performed. A diagnosis blinded to prior-known conditions was compared to the known defects severity (transmural, subendocardial) and defects position within the myocardial wall of the left ventricle (apical, anterior, inferior) for three body types (average male, large male, large female). Non-attenuation corrected, attenuation corrected and gated SPECT MPI were performed. The diagnostic sensitivity was improved when applying attenuation correction or gating techniques to identify subendocardial defects in the inferior, anterior and apical segments of the myocardial wall of the left ventricle for all three body types. Transmural defects could be identified without any attenuation correction or gating. ConclusionsThe diagnostic sensitivity was improved when applying AC or GSPECT techniques.

Use of annulus washer after debridement: A new mitral valve replacement technique for patients with severe mitral annular calcification

Extreme calcification of the mitral annulus (MAC) is a formidable challenge during mitral valve surgery, with the risk of serious and potentially fatal complications such as stroke, atrioventricular disruption, ventricular rup- ture, valve dehiscence, and periprosthetic leakage. 1 A vari- ety of surgical techniques have been developed that vary from avoiding or minimizing any decalcification 2 to exten- sive radical removal of the calcium bar followed by recon- struction of the atrioventricular annulus. 3-5 We describe our experience with an intermediate approach that involves limited debridement of the calcified annulus, allowing implantation of a good-sized prosthesis using a felt washer, sandwiched between the annulus and prosthesis, as a support. aortic calcification), and normothermic cardiopulmonary bypass were used in all patients. The mitral valve is approached transeptally. First the severity of the dis- ease and valvular dysfunction is reevaluated to finalize the surgical plan. This includes sizing the valve opening and estimating the debridement necessary to implant a good-sized valve. Exposure is optimized with a low threshold to extend the atrial septal incision to the dome of the left atrium and add a proximal aortotomy. The anterior leaflet is preserved and transposed posteriorly to support the annulus, and when doable, the posterior leaflet is released and also salvaged for support. Debridement is performed carefully piece by piece by rongeur, often using a dual ap- proach from the left atrium and aortic root. Great care is taken to avoid transmural defects in the atrioventricular groove or deep defects in the pos- terior wall muscle. Size and shape of the mitral opening are repeatedly reevaluated until it is deemed possible to place sutures and implant a pros- thesis of good size. In some cases this requires extensive debridement. The valve sutures are placed through or around the residual calcium and annu- lus, with pledgets on the ventricular side (Figure 1, A). Working through the aortotomy often allows better placement of valve sutures in the region of the central fibrous body. A 1- to 1.5-cm wide (1/2 inch) PTFE felt washer is inserted in between the annulus and sewing ring of the prosthesis from trigone to trigone posteriorly (Figure 1, B). The valve and the washer are tied down. The washer is then sutured to the atrial wall with a second suture line using running No. 4-0 polypropylene (Figure 1, C). Generous irrigation is performed repeatedly to clear the heart of loose pieces of calcium.

Cardiac motion compensation and resolution modeling in simultaneous PET-MR: a cardiac lesion detection study

Cardiac motion and partial volume effects (PVE) are two of the main causes of image degradation in cardiac PET. Motion generates artifacts and blurring while PVE lead to erroneous myocardial activity measurements. Newly available simultaneous PET-MR scanners offer new possibilities in cardiac imaging as MRI can assess wall contractility while collecting PET perfusion data. In this perspective, we develop a list-mode iterative reconstruction framework incorporating both tagged-MR derived non-rigid myocardial wall motion and position dependent detector point spread function (PSF) directly into the PET system matrix. In this manner, our algorithm performs both motion ‘deblurring’ and PSF deconvolution while reconstructing images with all available PET counts. The proposed methods are evaluated in a beating non-rigid cardiac phantom whose hot myocardial compartment contains small transmural and non-transmural cold defects. In order to accelerate imaging time, we investigate collecting full and half k-space tagged MR data to obtain tagged volumes that are registered using non-rigid B-spline registration to yield wall motion information. Our experimental results show that tagged-MR based motion correction yielded an improvement in defect/myocardium contrast recovery of 34–206% as compared to motion uncorrected studies. Likewise, lesion detectability improved by respectively 115–136% and 62–235% with MR-based motion compensation as compared to gating and no motion correction and made it possible to distinguish non-transmural from transmural defects, which has clinical significance given the inherent limitations of current single modality imaging in identifying the amount of residual ischemia. The incorporation of PSF modeling within the framework of MR-based motion compensation significantly improved defect/myocardium contrast recovery (5.1–8.5%, p < 0.01) and defect detectability (39–56%, p < 0.01). No statistical difference was found in PET contrast and lesion detectability based on motion fields obtained with half and full k-space tagged data.

Management of Large Bowel Injury During Laparoscopic Surgery

Management of Large Bowel Injury During Laparoscopic Surgery

Posterior Pedicle Lateral Nasal Wall Flap: New Reconstructive Technique for Large Defects of the Skull Base

Indications for expanded endoscopic approaches continue to grow, resulting in larger and more complex skull base defects. Reconstructive developments, however, have lagged our extirpative capabilities. As the complexity of clinical scenarios continues to escalate, challenging our current reconstructive strategies, we are compelled to develop alternative techniques to prevent cerebrospinal fluid leaks and protect neurovascular structures. In this article we show the anatomic basis for a new posterior pedicled flap from the lateral wall of the nose (Carrau-Hadad [C-H] flap) for the reconstruction of median skull base defects and present our early clinical experience. Using a cadaveric model, we designed a posterior pedicle flap comprising the nasal inferolateral wall mucoperiosteum. We applied this information clinically, to reconstruct transmural skull base defects. In our cadaveric model, we harvested and transposed C-H flaps into various defects of the planum sphenoidale, sella turcica, clivus, and nasopharynx. Then, we used the C-H flap in four patients, successfully reconstructing their clival (n = 3) and sellar (n = 1) surgical defects. All patients healed uneventfully. Our anatomic study and early clinical experience support the use of the posterior pedicle lateral nasal wall flap to reconstruct large cranial base defects resulting from endoscopic skull base surgery in properly selected patients.

Comparison of simultaneous and sequential SPECT imaging for discrimination tasks in assessment of cardiac defects

Simultaneous rest perfusion/fatty-acid metabolism studies have the potential to replace sequential rest/stress perfusion studies for the assessment of cardiac function. Simultaneous acquisition has the benefits of increased signal and lack of need for patient stress, but is complicated by cross-talk between the two radionuclide signals. We consider a simultaneous rest 99mTc-sestamibi/123I-BMIPP imaging protocol in place of the commonly used sequential rest/stress 99mTc-sestamibi protocol. The theoretical precision with which the severity of a cardiac defect and the transmural extent of infarct can be measured is computed for simultaneous and sequential SPECT imaging, and their performance is compared for discriminating (1) degrees of defect severity and (2) sub-endocardial from transmural defects. We consider cardiac infarcts for which reduced perfusion and metabolism are observed. From an information perspective, simultaneous imaging is found to yield comparable or improved performance compared with sequential imaging for discriminating both severity of defect and transmural extent of infarct, for three defects of differing location and size.

Endoscopic closure of GI fistulae by using an over-the-scope clip (with videos)

Preclinical studies have demonstrated the over-the-scope clip (OTSC) to be feasible and safe for closure of gastric, duodenal, and colonic perforations. A retrospective clinical study demonstrated the feasibility and preliminary safety of the OTSC for the treatment of GI bleeding and closure of acute GI perforations. Because the OTSC allows rapid and easy endoscopic organ wall closure, we hypothesized that it might be a useful tool to close GI fistulae. Case series. Academic medical center. Four consecutive patients with GI fistulae. In all patients, a 12-mm OTSC, in combination with the dedicated twin grasper, anchor device, or endoscopic suction, was used to facilitate endoscopic closure. In 2 cases, OTSCs allowed complete closure of a posttraumatic esophagopulmonary fistula and a chronic gastrocutaneous fistula. Leak tests and follow-up examination demonstrated complete leakproof closures. In 1 esophagopulmonary fistula and 1 jejunocutaneous fistula, the initial closure attempts using OTSCs were not successful because of chronic fibrotic changes and scarring at the fistula site. Both OTSCs were removed by using an endoscopic grasping forceps. The mean procedure time was 54 minutes (range 24-93 minutes). There were no procedure-related complications. Small sample size. The OTSC seems to be a feasible device to close chronic fistulae of the GI tract. It can achieve leakproof, full-thickness closure of transmural defects. Nevertheless, in circumstances of severe fibrosis and scarring, complete incorporation of the defect into the applicator cap and successful OTSC application might not be possible.

The Evaluation of Corrective Reconstruction Method For Reduced Acquisition Time and Various Anatomies of Perfusion Defect Using Channelized Hotelling Observer for Myocardial Perfusion SPECT.

We evaluated the effect of conventional and corrective image reconstruction methods on reduced acquisition time for detecting a myocardial perfusion (MP) defect in MP SPECT using the Channelized Hotelling Observer (CHO). Using the 4D Extended Cardiac-Torso (XCAT) phantom, we simulated realistic transmural and endocardial MP defects in various location and size. Realistic Tc-99m Sestamibi MP projection data were generated using an analytical projector that included the effects of attenuation (A), collimator-detector response (D) and scatter (S) for various count levels simulating different acquisition times. They were reconstructed using the 3D FBP without correction and a 3D OS-EM method with ADS correction followed by a smoothing filter with various cut-off frequencies. The CHO followed by receiver operating characteristics (ROC) methodology was applied to the reconstructed images to evaluate the detectability of a MP defect in each method for different defect anatomies and count levels. Areas under the ROC curve (AUC) were computed to assess the changes in the MP defect detection. The results showed that the 3D OS-EM with ADS corrections showed significantly less changes in AUC value and gave overall higher AUC values than FBP at all cut-off frequencies of the post smoothing filter, count levels and MP defect sizes. The difference in AUC increased towards less smoothed images where the 3D OS-EM with correction was able to provide similar AUC values with 20 - 40% reduction in acquisition time compared to FBP. The AUC values for smaller MP defects were lower for both reconstruction methods with smaller differences. We concluded that the 3D OS-EM with ADS corrections provides higher performance in the MP defect detection task. It allows increased reduction of acquisition time without loss of MP defect detection in MP SPECT compared to the conventional FBP method especially towards less smoothed images.

Transmural gastric closure and NOTES – How far have we come?

The ability to perform secure closure of transmural gastric defects will represent a significant milestone in the evolution of therapeutic gastrointestinal endoscopy. In 1958, the flexible fiberoptic endoscope was introduced by Larry Curtiss and Basil Hirschowitz as a diagnostic modality. Over the ensuing decades, an interventional focus gradually took shape – initially for more invasive diagnostic techniques, such as biopsies and polypectomies, but later encompassing hemostasis, pancreaticobiliary procedures (i. e., endoscopic retrograde cholangiopancreatography and sphincterotomies), fine needle aspirations under endoscopic ultrasound guidance, and endoscopic mucosal resection and endoscopic submucosal dissection for resection of early-stage cancers. However, this growing interventional focus was mostly confined to the gastrointestinal lumen.

Viable vascularized autologous patch for transmural myocardial reconstruction☆☆☆

Various patch materials currently used for cardiac reconstruction represent non-viable tissue with high susceptibility to infection and degeneration. We therefore introduce an innovative, autologous vascularized matrix with high regenerative potential for myocardial reconstruction. Autologous small bowel segments without mucosa, but with both the adjacent jejunal artery and vein, were harvested and used in a single-stage procedure for the replacement of right ventricular transmural defects (2 cm x 3 cm) in pigs (group A; n = 3). The autografts were revascularized by connecting jejunal vessels to the right internal thoracic artery and vein. Autologous pericardium was used as controls (group B; n = 3). All procedures were performed on beating hearts using a right heart bypass. After explantation (up to 6 months), the patches were investigated by standard histological analyses, immunohistochemistry and confocal microscopy. Postoperative complications, for example excessive bleeding, graft rupture or dislodgement due to the dynamic cardiac contractions, did not occur. In group A, newly formed cardiomyocytes positively stained for Nkx 2.5 and myosin heavy chain were identified 1 month after operation. The cardiomyocytes were localized in close proximity to mesenteric capillaries in a disseminated-like pattern and showed a strong tendency to form islets. In contrast, explanted pericardial patches appeared as fibrotic tissue without evidence of myocardial cells inside the patch. We developed a novel autologous graft with preserved vascularity that can be used for myocardial grafting. This vascularized matrix undergoes autologous repopulation with cardiomyocytes after transmural myocardial replacement. Vascularization represents an important prerequisite for myocardial guided tissue regeneration.

Magnetic Resonance Adenosine Perfusion Imaging in Patients After Coronary Artery Bypass Graft Surgery

The aim of the study was to evaluate the feasibility and diagnostic performance of the combination of adenosine stress perfusion and late gadolinium enhancement (LGE) in patients after coronary artery bypass graft surgery (CABG). Cardiac magnetic resonance (CMR) imaging allows the detection of significant coronary artery disease by adenosine stress perfusion and infarct imaging. Myocardial contrast kinetics may be altered in patients after CABG owing to more complex myocardial perfusion and different distances of the contrast bolus through different bypasses and native coronary vessels. Additionally, all studies have excluded patients after CABG. In all, 78 patients (age 66 +/- 8 years; 71 men) underwent CMR imaging including left ventricular function, first-pass adenosine stress perfusion (adenosine 140 microg/min/kg) using 0.05 mmol/kg body weight gadolinium-diethylenetriaminepenta-acetic acid and an additional 0.15 mmol/kg for LGE 1 day before invasive coronary angiography. Images were analyzed visually using the speed of contrast wash-in and maximal signal intensity. Transmural LGE defects of the size of a vessel or graft territory defined by angiography were considered true negatives, even when supplied by a stenosed/occluded vessel/graft. Stenoses >50% in grafts and grafted or ungrafted native vessels (diameter > or =2 mm) in invasive angiography were considered significant. The prevalence of patients with significant stenosis was 63% (69% functionally 1-vessel, 28% 2-vessel, and 3% 3-vessel disease). Sensitivity and specificity were 77% and 90%, respectively, on a patient basis, and 71% and 89% on a vessel territory basis. Sensitivity, if only areas supplied by grafts (n = 196) were evaluated, was 78% and specificity was 94%, compared with territories supplied by ungrafted native vessels (n = 51) with sensitivity and specificity of 63% and 91%, respectively. Sensitivity and specificity for the 53 areas with prior infarction were 88% and 79%, respectively. For patients after surgical revascularization, the combination of stress perfusion and LGE yields good diagnostic accuracy for the detection and localization of significant stenoses. However, sensitivity is reduced compared with published data in patients without CABG. Prior myocardial infarction can be examined without loss of accuracy.

Abstract 1855: Transmural Myocardial Repair with Engineered Heart Tissue Grafts

Engineered Heart Tissue (EHT) can be utilized to partially repair infarcted myocardium in rats. Here, we investigated the feasibility of EHT-grafts as transmural wall replacement in a heterotopic transplantation model. Methods: EHTs (diameter: 15 mm, thickness: 1– 4 mm) were generated from 12.5 ×10 6 neonatal rat heart cells, collagen type I, and matrigel. Similarly, non-contractile constructs were generated from rat cardiac fibroblasts (FB) and mesenchymal stem cells (MSC). Grafts were surgically inserted into large transmural defects (diameter: 6 mm) in the left ventricle of explanted donor hearts. Subsequently, “treated” hearts were transplanted into weight-matched (308±12 g; n=14), immune suppressed (cyclosporine, azathioprine, prednisolone) Wistar rats in heterotopic position. All transmural defects were also covered with an aortic patch to prevent bleeding from the ventricles. Sham surgeries included aortic patch implantations only. Heterotopic hearts were harvested after 28 days and subjected to morphological analyses by confocal laser scanning microscopy (CLSM). Results: Heart transplant weight at the time of implantation was 1.1±0.02 g (n=14). Heterotopic heart weight increased substantially in Sham (2.4±0.3 g, n=3) and FB-graft (2.1±0.1 g, n=3) animals, whereas MSC- (1.7±0.2 g, n=4) and EHT-graft (1.3±0.1 g, n=4; p&lt;0.05 vs. Sham) animals showed a smaller or no increase in weight, respectively. EHT grafts remained contractile throughout the observation period. CLSM revealed that EHT-grafts established oriented muscle bundles (actin and actinin staining) inside the transmural defects and were strongly vascularized (CD31 and smooth muscle actin staining; lectin labeling) leading to partial reconstitution of the myocardial continuity. This was not observed in animals with FB- and MSC-grafts. However, MSC-grafts, but not FB-grafts, contained newly formed vessels with a markedly larger diameter than observed in EHT-grafts (21±6 vs. 5±0.7 μm; p&lt;0.05). Conclusion: EHTs can be utilized as myocardial tissue grafts to reconstruct and prevent pathological enlargement of the left ventricle. This study constitutes a first step to establish a novel transmural myocardial repair technology involving fully bioengineered heart muscle.

Evaluation of endovenous radiofrequency ablation and laser therapy with endoluminal optical coherence tomography in an ex vivo model

This study evaluated the ability of endovascular optical coherence tomography (eOCT) to detect qualitative tissue alteration and quantitative changes of vein wall thickness and vein lumen diameter comparing endovenous radiofrequency ablation (RFA) and endovenous laser therapy (ELT) in an established ex vivo model. Endoluminal eOCT was performed by means of a new prototype rotating system (System M1, LightLab Imaging Inc, Boston, Mass) with automatic pullback of 1 mm/s. In the course of an eOCT examination of a 50-mm vein segment, 264 electronic cross section images with a spatial resolution of 15 to 20 mum are acquired. The eOCT scans were performed before and after treatment of each of 13 treated vein segments and of six control vein segments. Thirteen subcutaneous cow foot veins were reperfused in situ, and the defined 50-mm vein segments in the study were treated with RFA (n = 2) and ELT (n = 11). RFA followed the clinical VNUS-Closure protocol (VNUS Medical Technologies, San Jose, Calif) using a 6F 60-mm Closure-Plus catheter. ELT was performed using light of lambda = 980 nm with a laser power of 3 (n = 2), 5 (n = 2), and 7 W (n = 4) with a paced pullback protocol with laser irradiation for 1.5 seconds every 3 mm, resulting in linear endovenous energy densities (LEED) of 15, 25, and 35 J/cm. Using 11 W (n = 3) with a continuous pullback protocol at 3 mm/s resulted in a LEED of 36.5 J/cm. Ten histologic cross sections of each treated and control vein segment were correlated with the corresponding eOCT cross sections to evaluate qualitative representation of vein wall layers and tissue alterations such as ablation and vein wall perforation. In addition, 26 eOCT cross sections of every treated vein segment before and after treatment and every control vein segment were analyzed to calculate quantitative changes in media thickness and vein lumen diameter. In all specimens, qualitative analysis with eOCT demonstrated a clear match with histologic cross sections. A symmetrical, complete, circular disintegration of intima and media structures, without any transmural tissue defects, was shown after RFA. Pronounced semicircular tissue ablations (3 to 14 per 50 mm) and complete vessel wall perforations (0 to 16 per 50 mm) were detected after ELT. The quantitative analysis demonstrated a significant (P < .0001) increase in intima-media thickness after RFA (37.8% to 66.7%) and ELT (11.1% to 45.7%). A significant (P < .0001) reduction of vessel lumen diameter (36.3% to 42.2%) was found after RFA. Owing to the limited number of treated vein segments and inhomogeneous baseline vein lumen diameters, no linear correlation between laser energy level and effects on tissue such as ablation/perforation, media thickening, or vein lumen diameter could be identified. In our ex vivo cow foot model, eOCT is able to reproduce normal vein wall structures and endovenous acute thermal alterations, such as tissue ablation and vessel wall perforations. Endovenous eOCT images can also be analyzed quantitatively to measure media thickness or vein lumen diameter. Endovascular OCT could become a valuable alternative tool for morphologic investigation of tissue alterations after endovenous thermal procedures.