Alagille Syndrome and Repeat Oxygenator Failure during Cardiopulmonary Bypass: A Word of Caution.

Alagille syndrome is an autosomal dominant disorder that is caused by heterozygous mutation of JAG1 or NOTCH2 gene that impacts several multisystem organs including but may not be limited to the liver, heart, musculoskeletal, skin, and the eyes. The most common congenital heart defect associated with Alagille syndrome is multilevel right ventricular outflow tract obstruction with multiple central and peripheral branch pulmonary arterial stenoses occurring in up to two-thirds of these patients. We report two cases of Alagille syndrome who underwent extensive pulmonary arterial branch rehabilitation and experienced unusual oxygenator failure during cardiopulmonary bypass (CPB). We present lessons learned from these two cases and the changes that we implemented in our practice that facilitated smooth conduct of CPB in other cases that we performed subsequently.

Tethered Liquid Perfluorocarbon Coating for 72 Hour Heparin-Free Extracorporeal Life Support.

Coagulopathic complications during extracorporeal life support (ECLS) result from two parallel processes: 1) foreign surface contact and shear stress during blood circulation and 2) administration of anticoagulant drugs to prevent circuit thrombosis. To address these problems, biocompatible surfaces are developed to prevent foreign surface-induced coagulopathy, reducing or eliminating the need for anticoagulants. Tethered liquid perfluorocarbon (TLP) is a nonadhesive coating that prevents adsorption of plasma proteins and thrombus deposition. We examined application of TLP to complete ECLS circuits (membranes, tubing, pumps, and catheters) during 72 hours of ECLS in healthy swine (n = 5/group). We compared TLP-coated circuits used without systemic anticoagulation to standard of care: heparin-coated circuits with continuous heparin infusion. Coagulopathic complications, device performance, and systemic effects were assessed. We hypothesized that TLP reduces circuit thrombosis and iatrogenic bleeding, without impeding gas exchange performance or causing untoward effects. No difference in bleeding or thrombotic complication rate was observed; however, circuit occlusion occurred in both groups (TLP = 2/5; CTRL = 1/5). TLP required elevated sweep gas rate to maintain normocapnia during ECLS versus CTRL (10-20 vs. 5 L/min; p = 0.047), suggesting impaired gas exchange. Thrombus deposition and protein adhesion on explanted membranes were comparable, and TLP did not preserve platelet or blood cell counts relative to controls. We conclude that neither TLP nor standard of care is an efficacious solution to prevent coagulation disturbances during ECLS. Further testing of promising biomaterials for ECLS utilizing the model outlined here is warranted.

Heparin-Free Extracorporeal Life Support Using Tethered Liquid Perfluorocarbon: A Feasibility and Efficacy Study.

Coagulation management is the leading challenge during extracorporeal life support (ECLS) due to shear stress and foreign-surface-induced coagulation disturbance during circulation. A nonadhesive, liquid-infused coating called tethered liquid perfluorocarbon (TLP) was developed to prevent adhesion of blood on medical materials. We investigated the novel application of TLP to commercial ECLS circuits compared with standard heparin-coated circuits in vivo in anesthetized swine for 6 hours veno-venous ECLS (1 L/min blood flow) without systemic anticoagulation (n = 3/group). We hypothesized that TLP coating permits heparin-free circulation without untoward effects while reducing thrombus deposition compared with controls. Vital signs, respiration, gas transfer, coagulation, and histology were assessed. Scanning electron microscopy (SEM), elemental mapping, and digital imaging were used to assess thrombus deposition after circulation. There were no group differences in vitals, gas exchange, coagulation, and histology. In both groups, ECLS enabled a decrease in minute volume and end-tidal CO2, with concomitant increase in pH (p < 0.05). Scanning electron microscopy and digital imaging revealed significant thrombus on heparin-coated membranes, which was reduced or absent on TLP-coated materials. Tethered liquid perfluorocarbon permitted heparin-free ECLS without altering device performance and prevented thrombus deposition versus immobilized heparin. Pending multiday in vivo testing, TLP is a promising biomaterial solution to eliminate anticoagulation requirements during ECLS.

Thromboelastography on-the-go: Evaluation of the TEG 6s device during ground and high-altitude Aeromedical Evacuation with extracorporeal life support.

BACKGROUND: Coagulation monitoring capabilities during transport are limited. Thromboelastography (TEG) is a whole-blood clotting test measuring clot formation, stabilization, and fibrinolysis and is traditionally performed in a laboratory. We evaluated a new point-of-care TEG analyzer, TEG 6s (Haemonetics, Braintree, MA), in a large animal model of combat-relevant trauma managed with extracorporeal life support during ground and high-altitude aeromedical evacuation. The objective was to compare TEG 6s used during transport versus the predicate device, TEG 5000, used in the laboratory. We hypothesized that TEG 6s would be comparable with TEG 5000 during dynamically changing transport conditions. METHODS: Thromboelastography parameters (R, K, angle, MA, LY30) derived by TEG 6s and TEG 5000 were compared during transport of 8 swine. TEG 6s was transported with animals during ground transport and flight. TEG 5000 was stationary in an adjacent building. TEG 6s activated clotting time (ACT) was compared with a Hemochron Junior ACT analyzer (Accriva Diagnostics, San Diego, CA). Statistics were performed using SAS 9.4 with Deming regressions, Spearman correlations, and average differences compared. RESULTS: Correlation between devices was stronger at sea-level (R, r = 0.7413; K, r = 0.7115; angle, r = 0.7192; MA, r = 0.8386; LY30, r = 0.9099) than during high-altitude transport (R, r = 0.4787; K, r = 0.4007; angle, r = 0.3706; MA, r = 0.6573; LY30, r = 0.8481). Method agreement was comparable during stationary operation (R, r = 0.7978; K, r = 0.7974; angle, r = 0.7574; MA, r = 0.7841; LY30, r = 0.9140) versus ground transport (R, r = 0.7927; K, r = 0.6246; angle, r = 0.6967; MA, r = 0.9163; LY30, r = 0.8603). TEG 6s ACT trended higher than Hemochron ACT when subjects were heparinized (average difference, 1,442 ± 1,703 seconds) without a methodological difference by Deming regression. CONCLUSION: Mobile TEG 6s during ground and altitude transport is feasible and provides unprecedented information to guide coagulation management. Future studies should assess the precision and accuracy of TEG 6s during transport of critically ill.

Duplex Ultrasound Surveillance After Uncomplicated Endovascular Abdominal Aortic Aneurysm Repair.

OBJECTIVES: Health-care costs and risks of radiation and intravenous contrast exposure challenge computed tomography angiography (CTA) as the standard surveillance method after endovascular abdominal aortic aneurysm repair (EVAR). We reviewed our experience using Duplex ultrasound scan (DUS) as an initial and subsequent surveillance technique after uncomplicated EVAR. METHODS: The medical records of patients who underwent EVAR from 2004 to 2014 with at least 1 postoperative imaging study were retrospectively reviewed. Duplex ultrasound scan was the primary modality, with CTA reserved for patients with suspicious findings. RESULTS: Mean follow-up was 3.2 years for 266 patients. Fifty-seven endoleaks (7 type I, 50 type II) were detected in 51 patients (19%). Nineteen (33%) endoleaks were identified and monitored by DUS alone. Nine (16%) endoleaks were identified on CTA without prior DUS. Twenty-two (39%) endoleaks were identified on DUS and confirmed by CTA; 6 of these patients had a secondary intervention. When compared to subsequent CTA, there were 7 discordant results: 4 false-negative and 3 false-positive endoleaks on DUS. Two of these patients with discordant results required intervention. Follow-up CTA was not obtained for the other 2 patients due to severe comorbidities including renal disease. One of these patients eventually developed abdominal aortic aneurysm rupture and death. Among 88 patients with both DUS and CTA, positive predictive value and negative predictive value for DUS were 0.88 and 0.94, respectively. Sac size on DUS compared to CTA resulted in an interclass correlation coefficient of r = .84. CONCLUSIONS: In our experience, DUS was safe and effective for initial and follow-up surveillance after uncomplicated EVAR.