Hyperacute graft dysfunction in an orthotopic heart transplant in the presence of non-HLA antibodies.

Antibody-mediated rejection (AMR) in heart transplants in the absence of anti-HLA donor-specific antibody (DSA) is not well studied or documented. This case reviews hyperacute fulminant graft dysfunction suspected to be mediated by non-HLA antibodies. After cross clamp removal, the patient developed severe pulmonary edema, profound coagulopathy, and biventricular failure. The patient's presumed AMR, cardiogenic shock, and coagulopathy were treated with extracorporeal membrane oxygenation (ECMO), plasmapheresis, intravenous immunoglobulin (IVIG), multiple blood products, and prothrombin complex concentrate. The recipient was 0% panel-reactive antibody (PRA), ABO, and crossmatch compatible. Intraoperative biopsy sample revealed a thrombotic process suggestive of a coagulation pathway activated by AMR; however, no C4d deposition was detected. Postmortem biopsies also suggested AMR. Retrospective testing of the patient's pretransplant serum revealed strong antiangiotensin II type 1 receptor (AT1R) antibodies and a strongly positive endothelial cell crossmatch. Anti-AT1R antibodies are known to be AT1 receptor agonists and may trigger inflammation and activate the extrinsic coagulation pathway. Given the potential effects of signaling through the AT1R, the patient's preexisting anti-AT1R antibodies and procoagulant therapy may have adversely affected the patient's clinical course.

Intra-operative imaging of surgical margins of canine soft tissue sarcoma using optical coherence tomography.

Optical coherence tomography (OCT) is a rapid non-invasive imaging technique that has shown high sensitivity for intra-operative surgical margin assessment in human breast cancer clinical trials. This promising technology has not been evaluated in veterinary medicine. The objective of this study was to correlate normal and abnormal histological features with OCT images for surgical margins from excised canine soft tissue sarcoma (STS) and to establish image evaluation criteria for identifying positive surgical margins. Fourteen client-owned dogs underwent surgical resection of a STS and OCT imaging of 2 to 4 areas of interest on the resected specimen were performed. Following imaging these areas were marked with surgical ink and trimmed for histopathology evaluation. Results showed that different tissue types had distinct characteristic appearances on OCT imaging. Adipose tissue exhibited a relatively low scattering and a honey-comb texture pattern. Skeletal muscle and sarcoma tissue were both dense and highly scattering. While sarcoma tissue was highly scattering, it did not have organized recognizable structure in contrast to muscle which showed clear fibre alignment patterns. In this investigation, we showed different tissue types had different and characteristic scattering and image texture appearances on OCT, which closely correlate with low-power histology images. Given the differentiation between tissue types the results support that OCT could be used to identify positive surgical margins immediately following resection of STS. Further research is needed to assess the diagnostic accuracy of this method for surgical margin assessment.

Complementary use of polarization-sensitive and standard OCT metrics for enhanced intraoperative differentiation of breast cancer.

We report the development and implementation of an intraoperative polarization-sensitive optical coherence tomography (PS-OCT) system for enhancing breast cancer detection. A total of 3440 PS-OCT images were intraoperatively acquired from 9 human breast specimens diagnosed by H&E histology as healthy fibro-adipose tissue (n = 2), healthy stroma (n = 2), or invasive ductal carcinoma (IDC, n = 5). A standard OCT-based metric (coefficient of variation (CV)) and PS-OCT-based metrics sensitive to biological tissue from birefringence (i.e., retardation and degree of polarization uniformity (DOPU)) were derived from 398 statistically different and independent images selected by correlation coefficient analysis. We found the standard OCT-based metric and PS-OCT-based metrics were complementary for the differentiation of healthy fibro-adipose tissue, healthy stroma, and IDC. While the CV of fibro-adipose tissue was significantly higher (p<0.001) than those of either stroma or IDC, the CV difference between stroma and IDC was minimal. On the other hand, stroma was associated with significantly higher (p<0.001) retardation and significantly lower (p<0.001) DOPU as compared to IDC. By leveraging the complementary information acquired by the intraoperative PS-OCT system, healthy fibro-adipose tissue, healthy stroma, and IDC can be differentiated with an accuracy of 89.4%, demonstrating the potential of PS-OCT as an adjunct modality for enhanced intraoperative differentiation of human breast cancer.

Intraoperative optical coherence tomography of the human thyroid: Feasibility for surgical assessment.

Thyroid nodules assessed with ultrasound and fine-needle aspiration biopsy are diagnosed as "suspicious" or "indeterminate" in 15%-20% of the cases. Typically, total thyroidectomy is performed in such cases; however, only 25%-50% are found to be cancerous upon final histopathologic analysis. Here we demonstrate optical coherence tomography (OCT) imaging of the human thyroid as a potential intraoperative imaging tool for providing tissue assessment in real time during surgical procedures. Fresh excised tissue specimens from 28 patients undergoing thyroid surgery were imaged in the laboratory using a benchtop OCT system. Three-dimensional OCT images showed different microstructural features in normal, benign, and malignant thyroid tissues. A similar portable OCT system was then designed and constructed for use in the operating room, and intraoperative imaging of excised thyroid tissue from 6 patients was performed during the surgical procedure. The results demonstrate the potential of OCT to provide real-time imaging guidance during thyroid surgeries.

Intraoperative optical coherence tomography for soft tissue sarcoma differentiation and margin identification.

BACKGROUND AND OBJECTIVE: Sarcomas are rare but highly aggressive tumors, and local recurrence after surgical excision can occur in up to 50% cases. Therefore, there is a strong clinical need for accurate tissue differentiation and margin assessment to reduce incomplete resection and local recurrence. The purpose of this study was to investigate the use of optical coherence tomography (OCT) and a novel image texture-based processing algorithm to differentiate sarcoma from muscle and adipose tissue. STUDY DESIGN AND METHODS: In this study, tumor margin delineation in 19 feline and canine veterinary patients was achieved with intraoperative OCT to help validate tumor resection. While differentiation of lower-scattering adipose tissue from higher-scattering muscle and tumor tissue was relatively straightforward, it was more challenging to distinguish between dense highly scattering muscle and tumor tissue types based on scattering intensity and microstructural features alone. To improve tissue-type differentiation in a more objective and automated manner, three descriptive statistical metrics, namely the coefficient of variation (CV), standard deviation (STD), and Range, were implemented in a custom algorithm applied to the OCT images. RESULTS: Over 22,800 OCT images were collected intraoperatively from over 38 sites on 19 ex vivo tissue specimens removed during sarcoma surgeries. Following the generation of an initial set of OCT images correlated with standard hematoxylin and eosin-stained histopathology, over 760 images were subsequently used for automated analysis. Using texture-based image processing metrics, OCT images of sarcoma, muscle, and adipose tissue were all found to be statistically different from one another (P ≤ 0.001). CONCLUSION: These results demonstrate the potential of using intraoperative OCT, along with an automated tissue differentiation algorithm, as a guidance tool for soft tissue sarcoma margin delineation in the operating room. Lasers Surg. Med. 49:240-248, 2017. © 2017 Wiley Periodicals, Inc.

The MVAD pump: motor stator core loss characterization.

Investigation of the miniature ventricular assist device (MVAD) pump motor stator core loss behavior was conducted. During operation, the ferromagnetic core in the pump's motor is magnetized by alternating magnetic fields, which, in turn, create intrinsic energy losses in the core material; these losses are known as core losses. A core loss fixture and a method to characterize the magnetic behavior of the MVAD pump stator over a range of frequencies were developed. The MVAD pump motor design features a three phase brushless DC stator with ferromagnetic laminations and copper wire windings arranged in a six slot configuration. The stator's magnetic behavior is important because its core magnetic losses impact pump system efficiency. A system to measure the core loss of MVAD pump stators was developed using a custom core loss fixture consisting of 16 copper wire turns wound in a closed loop geometry bundle; the stator under test was then placed within this bundle. The instrumentation consisted of a signal generator, a power amplifier, and a power analyzer. Power analyzer parameters of current, voltage, and power were collected for several runs with a sinusoidal frequency sweep of 0 to 50 kHz; data were collected for the fixture with and without stators. The magnetic losses inherent to the fixture were characterized independently as a baseline presenting a flat frequency response. The core loss power measurements of individual stators yielded a characteristic bandpass frequency response morphology with a peak core loss found around 2.3 to 2.5 kHz. In conclusion, this method could be used to describe the transfer function of the stator's core magnetic behavior. It also has the potential to be used for future motor evaluation and for investigation of core loss performance variability between different stators during manufacturing operations. CAUTION: Investigational device. Limited by United States law to investigational use.