Vinay Thohan

Practical value of identifying antibodies to cryptic HLA epitopes in cardiac transplantation

BACKGROUND Identification of antibodies to human leukocyte antigens (HLA) by single antigen bead arrays has led to the common practice of virtual crossmatching. However, inappropriate assignment of anti-HLA specificities can lead to false-positive virtual crossmatching, resulting in the decline of potentially crossmatch-negative organ offers. In this study we describe identification of antibodies to cryptic HLA present on denatured forms of HLA on single antigen bead array and provide a reassessment of calculated panel-reactive antibody (CPRA) based on elimination of false-positive reactions due to antibodies to cryptic HLA epitopes. METHODS Sera from 96 patients with positive HLA antibodies detected on a standard single antigen bead platform were tested under denaturing conditions and with a new single antigen bead product (iBeads; One Lambda, Inc., Canoga Park, CA) to identify antibodies to cryptic HLA vs. native HLA. Flow cytometry crossmatching and complement-fixation assays were performed to assess clinical relevance. RESULTS Antibodies to cryptic HLA were present in approximately 21% of patients on our waiting list for cardiac transplantation. These antibody responses were not associated with factors commonly thought to be associated with antibody responses to HLA such as age, gender, transfusions or presence of circulatory support. CONCLUSIONS Antibodies to cryptic HLA can be reliably identified by iBeads technology, and usually do not fix complement nor produce positive flow cytometry crossmatches. Identification and removal of antibodies to cryptic HLA from the panel of unacceptable antigens may have dramatic and meaningful effects on CPRA and virtual crossmatch strategies.

Role of Echocardiography in the Evaluation of Left Ventricular Assist Devices: the Importance of Emerging Technologies

The role of left ventricular assist devices (LVAD) in patients with end-stage heart failure is well known, both as a temporary treatment before transplantation and as destination therapy, in a scenario of a relative shortage of donors to satisfy the increasing requests for transplantation. The increased population of LVAD patients needs careful imaging assessment before, during, and after LVAD implantation; echocardiography is the best tool for their evaluation and is considered the diagnostic technique of choice for the assessment before, during, and after device implantation. Although the conventional echocardiographic assessment is quite effective in evaluating the main critical issues, the role of new technologies like three-dimensional echocardiography and myocardial deformation measurements is still not properly clarified. In this review, we aim to provide an overview of the main elements that should be considered in the assessment of these patients, underlining the role that could be played by new techniques to improve the diagnostic and prognostic effectiveness of echocardiography in this setting.

Expecting the unexpected: right atrial mass in a transplant patient

We present a 71‐year‐old male, who had had a heart transplantation 24 years prior, who came to our clinic with a low‐grade fever and a new II/VI holosystolic murmur. Echocardiography showed a large mass in the right atrium with attachment near the junction of the right atrium and superior vena cava. The patient was taken to the operating room for resection of the mass. Microscopic evaluation was consistent with thrombus. Differential diagnosis of cardiac masses after cardiac transplant includes tumour, thrombus, and vegetation. Final diagnosis can be challenging; multimodality imaging and biopsy or resection often are required for final diagnosis.