Human Atrial Fibrillation Drivers Resolved With Integrated Functional and Structural Imaging to Benefit Clinical Mapping

OBJECTIVES

This study sought to improve atrial fibrillation (AF) driver identification by integrating clinical multielectrode mapping with driver fingerprints defined by high-resolution ex vivo 3-dimensional (3D) functional and structural imaging.

BACKGROUND

Clinical multielectrode mapping of AF drivers suffers from variable contact, signal processing, and structural complexity within the 3D human atrial wall, raising questions on the validity of such drivers.

METHODS

Sustained AF was mapped in coronary-perfused explanted human hearts (n = 11) with transmural near-infrared optical mapping (∼0.3 mm² resolution). Simultaneously, custom FIRMap catheters (∼9 × 9 mm² resolution) mapped endocardial and epicardial surfaces, which were analyzed by Focal Impulse and Rotor Mapping activation and Rotational Activity Profile (Abbott Labs, Chicago, Illinois). Functional maps were integrated with contrast-enhanced cardiac magnetic resonance imaging (∼0.1 mm³ resolution) analysis of 3D fibrosis architecture.

RESULTS

During sustained AF, near-infrared optical mapping identified 1 to 2 intramural, spatially stable re-entrant AF drivers per heart. Driver targeted ablation affecting 2.2 ± 1.1% of the atrial surface terminated and prevented AF. Driver regions had significantly higher phase singularity density and dominant frequency than neighboring nondriver regions. Focal Impulse and Rotor Mapping had 80% sensitivity to near-infrared optical mapping-defined driver locations (16 of 20), and matched 14 of 20 driver visualizations: 10 of 14 re-entries seen with Rotational Activity Profile; and 4 of 6 breakthrough/focal patterns. Focal Impulse and Rotor Mapping detected 1.1 ± 0.9 false-positive rotational activity profiles per recording, but these regions had lower intramural contrast-enhanced cardiac magnetic resonance imaging fibrosis than did driver regions (14.9 ± 7.9% vs. 23.2 ± 10.5%; p < 0.005).

CONCLUSIONS

The study revealed that both re-entrant and breakthrough/focal AF driver patterns visualized by surface-only clinical multielectrodes can represent projections of 3D intramural microanatomic re-entries. Integration of multielectrode mapping and 3D fibrosis analysis may enhance AF driver detection, thereby improving the efficacy of driver-targeted ablation.

Incidental Finding of an Aorto-Right Atrial Fistula in a Patient Undergoing Repair of a Sinus of Valsalva Aneurysm

A sinus of Valsalva aneurysm is a rare malformation of the aortic root that can fistulize to another cardiac structure such as the right atrium. Although transthoracic echocardiography and computed tomography angiography have demonstrated utility for the diagnosis of a sinus of Valsalva-to-right atrial fistula, there are few cases where a misdiagnosis may occur. Intraoperative transesophageal echocardiography may be an essential imaging tool for the diagnosis and management of incidental findings such as a sinus of Valsalva-to-right atrial fistula during cardiac surgery and should be used routinely.

Exocrine drainage of the transplanted pancreas: A review

Pancreas transplant is an important treatment option for insulin dependent diabetic patients as it may result in physiologic euglycemia. Improvements in surgical technique, graft preservation, immunosuppression, diagnosis and management of rejection, and management of post-transplant complications have led to improved patient survival.

There are several technical variables to consider when performing a pancreas transplant. One is the type of exocrine drainage to be used. The most common types of exocrine drainage are enteric or bladder drainage. Gastric- exocrine drainage has also been recently introduced. The most commonly cited complications associated with bladder drainage include metabolic complications, urologic complications and the need for enteric conversion.

Many complications related to bladder drainage can be managed non-operatively with Foley catheter drainage. For those complications that cannot be managed in this manner, enteric conversion is an option. Complications associated with enteric drainage include anastomotic leak and intra-abdominal abscess, although at rates lower than cited in the early literature on the topic. Bladder drainage of exocrine secretions and enteric drainage of exocrine secretions, or a staged procedure with bladder drainage followed by indicated or elective enteric conversion are reasonable options for drainage of the exocrine secretions of the pancreas. Gastric-exocrine drainage is a promising therapy deserving of future exploration.

Donations After Circulatory Death in Liver Transplant

The supply of liver grafts for treatment of end-stage liver disease continues to fall short of ongoing demands. Currently, most liver transplants originate from donations after brain death. Enhanced utilization of the present resources is prudent to address the needs of the population. Donation after circulatory or cardiac death is a mechanism whereby the availability of organs can be expanded. Donations after circulatory death pose unique challenges given their exposure to warm ischemia. Technical principles of donations after circulatory death procurement and pertinent studies investigating patient outcomes, graft outcomes, and complications are highlighted in this review. We also review associated risk factors to suggest potential avenues to achieve improved outcomes and reduced complications. Future considerations and alternative techniques of organ preservation are discussed, which may suggest novel strategies to enhance preservation and donor expansion through the use of marginal donors. Ultimately, without effective measures to bolster organ supply, donations after circulatory death should remain a consideration; however, an understanding of inherent risks and limitations is necessary.

Rituximab, Dexamethasone, Cytarabine, and Cisplatin as Effective Platinum-Based Salvage Chemotherapy for Periportal Posttransplant Lymphoproliferative Disorder After an Orthotopic Liver Transplant

Posttransplant lymphoproliferative disorder is a group of heterogenous disorders that occur after solid-organ transplant. The overall incidence is between 1% and 20%. In orthotopic liver transplant recipients, the reported incidence ranges from 2% to 10%, while the incidence is greater in children (9.7%-11%) and lesser in adults (1.7%-3%). The following treatment options are considered for patients with posttransplant lymphoproliferative disorder: reduction of immunosuppression, single-agent rituximab, rituximab and chemotherapy, surgery and radiation, antivirals targeted at the Epstein-Barr virus, and cytotoxic T-lymphocytes targeting the Epstein-Barr virus. This report describes a 61-year-old man who presented after an orthotopic liver transplant with a large periportal soft tissue mass that was shown on biopsy to be a monomorphic, CD20+, diffuse, large B-cell lymphoma, nongerminal center type. He was treated with reduced immunosuppression, followed by single-agent rituximab, then with an anthracycline-based chemotherapy regimen: rituximab, etoposide, prednisone, vincristine, doxorubicin, and then a platinum-based salvage chemotherapy with rituximab, dexamethasone, cytarabine, and cisplatin with a good response.

Preservation solutions for cardiac and pulmonary donor grafts: a review of the current literature

Hypothermic preservation of donor grafts is imperative to ameliorate ischemia related cellular damage prior to organ transplantation. Numerous solutions are in existence with widespread variability among transplant centers as to a consensus regarding the optimal preservation solution. Here, we present a concise review of pertinent preservation studies involving cardiac and pulmonary allografts in an attempt to minimize the variability among institutions and potentially improve graft and patient survival. A biochemical comparison of common preservation solutions was undertaken with an emphasis on Euro Collins (EC), University of Wisconsin (UW), histidine-tryptophan-ketoglutarate (HTK), Celsior (CEL), Perfadex (PER), Papworth, and Plegisol. An appraisal of the literature ensued containing the aforementioned preservation solutions in the setting of cardiac and pulmonary transplantation. Available evidence supports UW solution as the preservation solution of choice for cardiac transplants with encouraging outcomes relative to notable contenders such as CEL. Despite its success in the setting of cardiac transplantation, its use in pulmonary transplantation remains suboptimal and improved outcomes may be seen with PER. Together, we suggest, based on the literature that the use of UW solution and PER for cardiac and pulmonary transplants, respectively may improve transplant outcomes such as graft and patient survival.

Percutaneous distal limb perfusion via portable, miniaturized, extracorporeal membrane oxygenation resuscitation

As extracorporeal membrane oxygenation systems become miniaturized, their role for rapid implementation, as an adjunct to resuscitation and high-risk percutaneous interventions, grows. We describe a percutaneous approach to short term mechanical circulatory support, in the setting of cardiogenic shock, which employs a percutaneous, self-contained, distal limb perfusion system. We feel that this technique is highly important for both interventional cardiologists and cardiothoracic surgeons as well.

Strength over time of a resorbable bioscaffold for body wall repair in a dog model

The change in strength over time of a biomaterial derived from the small intestinal submucosa (SIS) was determined in a dog model of body wall repair. Full-thickness body wall defects measuring 8 x 12 cm were surgically created and then repaired with a multilaminate eight-layer form of SIS in 40 dogs. Five dogs were sacrificed at each of the following time points: 1 day, 4 days, 7 days, 10 days, and 1, 3, 6, and 24 months. Ball burst tests that measured biaxial ultimate load-bearing capability were performed on the device prior to implantation and on the device/implant site at the time of sacrifice. The strength of the device at the time of implant was approximately 73 +/- 12 pounds. The strength of the implant site diminished to 40 +/- 18 pounds at 10 days, and then progressively increased to a value of 156 +/- 26 pounds at 24 months (P < 0.05). The clinical utility of a degradable biomaterial such as SIS depends on a balance between the rate of degradation and the rate of host remodeling. Naturally occurring extracellular matrix scaffolds such as SIS show rapid degradation with associated and subsequent remodeling to a tissue with strength that exceeds that of the native tissue when used as a body wall repair device.