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Purpose Unfractionated heparin exposure in patients undergoing mechanical circulatory support device (MCSD) implantation increases the risk for developing heparin-induced-thrombocytopenia (HIT). The false positive rate of HIT in this population using current standard testing is unknown. Postoperative and device related thrombocytopenia complicate the HIT diagnosis. Methods A retrospective analysis of patients undergoing MCSD pre-implantation assessment or implantation of MCSD (October 2014 - August 2020) was performed. The primary objective was to assess the incidence of HIT with positive PF4 IgG ELISA (PF4) and serotonin release (SRA) assays. False positive HIT was defined as PF4 ≥0.4 optical density (OD) and negative SRA. Argatroban usage was also assessed. Results 366 patients with 512 tests were analyzed. PF4 tests were performed in 128 patients (158 tests) undergoing pre-implantation assessment, 136 patients (185 tests) with non-durable devices (primarily Impella®), and 102 (169 tests) patients with durable devices (72 ventricular assist devices, 30 total artificial hearts). 25% (92/366) of patients had positive PF4 ≥0.4 OD and had subsequent SRA performed (92 patients, 122 tests). True positive HIT was documented in 13% (12/92) of PF4 positive patients consisting of 1 pre-implantation, 9 non-durable MCSD, and 2 durable MCSD patients. The mean PF4 for true positive HIT was 2.2±0.7 OD. False positive HIT was documented in 15% (19/128) of pre-implantation patients (mean PF4 0.9±0.6 OD), 14% (19/136) of non-durable MCSD patients (mean PF4 0.8±0.5 OD), and 41% (42/102) of durable MCSD patients (mean PF4 1.1±0.6 OD). Argatroban was administered in 40% (37/92) of patients with a positive PF4 and 67% (25/37) of patients with a negative SRA. Conclusion Without clinical suspicion of HIT, preoperative PF4 testing is not recommended. Patients with non-durable MCSD devices are at the highest risk of developing HIT (7%). Although a PF4 ≥0.4 OD is considered a positive screening test for HIT, a higher threshold should be considered for MCSD patients. To our knowledge, this is the first in depth assessment of the incidence of HIT in patients undergoing pre-implantation evaluation for both non-durable and durable MCS devices.

BACKGROUND ORTHO VISION Analyzer (Vision), is an immunohematology instrument using ID-MT gel card technology with digital image processing. It has a continuous, random sample access with STAT priority processing. The efficiency and ease of operation of Vision was evaluated at 5 medical centers. METHODS De-identified patient samples were tested on the ORTHO ProVue Analyzer (ProVue) and repeated on the Vision mimicking the daily workload pattern. Turnaround times (TAT) were collected and compared. Operators rated key features of the analyzer on a scale of 1 to 5. RESULTS A total of 507 samples were tested on both instruments at the 5 trial sites. The mean TAT (SD) were 31.6 minutes (5.5) with Vision and 35.7 minutes (8.4) with ProVue, which renders a 12% reduction. Type and screens were performed on 381 samples; the mean TAT (SD) was 32.2 minutes (4.5) with Vision and 37.0 minutes (7.4) with ProVue. Antibody identification with eleven panel cells was performed on 134 samples on Vision; TAT (SD) was 43.2 minutes (8.3). The installation, training, configuration, maintenance and validation processes are all streamlined to provide a short implementation time. The average rating of main functions by the operators was 4.1 to 4.8. Opportunities for improvement, such as flexibility with editing QC results, maintenance schedule, and printing options were identified. The capabilities to perform serial dilutions, to accept pediatric tubes, and review results by e-Connectivity are enhancements over the ProVue. CONCLUSIONS Vision provides shorter TAT compared to ProVue. Every site described a positive experience using Vision.

Epstein-Barr virus (EBV) is known to play a key role in the development of several lymphoproliferative disorders (LPD), ranging from indolent lesions to highly aggressive lymphomas. Here, we describe an incidentally detected unique case of a localized EBV-positive large B cell LPD within a popliteal artery aneurysmal hematoma of a 91-year-old male. Histopathologic examination of an expanding right thigh mass demonstrated organizing hematoma with microscopic clusters of atypical large lymphoid cells with a non-germinal center B cell immunophenotype, a high proliferation rate by Ki-67 staining, and strong positivity for EBV-encoded RNA (EBER) by in situ hybridization. An 18-month follow-up revealed no evidence of disease progression. The presence of cytologically malignant EBV-positive large B cells supports a LPD, with a differential diagnosis that includes a spectrum of EBV-associated lesions, including diffuse large B cell lymphoma (DLBCL) of the elderly, DLBCL associated with chronic inflammation, as well as a variety of recently described indolent EBV-associated large B cell proliferations occurring in cardiac fibrin thrombi, atrial myxomas, and other unusual sites. This case is the first report of an indolent fibrin-associated EBV-positive LPD occurring in an aneurysmal hematoma of the extremity. This lesion may represent the indolent end of the spectrum of EBV-associated large B cell proliferations, and recognition of such lesions may prevent unnecessary aggressive treatment.