Hemocompatibility Evaluation of a Novel Ambulatory Pulmonary Assist System Using a Lightweight Axial-Flow Pump

The Pulmonary Assist System (PAS) is currently under development as a wearable respiratory assist system. In this study, the hemocompatibility of the PAS's axial-flow mechanical pump (AFP) was compared to other contemporary mechanical pumps in an acute ovine model. The PAS was attached to a normal sheep in a venovenous configuration using one of three pumps: 1) AFP, 2) ReliantHeart HeartAssist 5 (control), or 3) Abbott Pedimag (control) (n = 5 each). Each sheep was supported on the PAS for 12 hours with two L/minute of blood flow and four L/minute of sweep gas. Hemolysis, coagulation, inflammation, and platelet activation and loss were compared among the groups. In this study, the plasma-free hemoglobin (pfHb) was less than 10 mg/dl in all groups. The pfHb was significantly lower in the AFP group compared to other groups. There was no significant clot formation in the pumps and oxygenators in all groups. Furthermore, no significant differences in coagulation (oxygenator resistance, fibrinopeptide A), inflammation (white blood cell counts, IL-8), and platelet activation and loss (p-selectin, platelet counts) were observed among the groups (all, p > 0.05). This study demonstrates equivalent hemocompatibility of the PAS's AFP to other contemporary mechanical pumps with a reduced level of hemolysis on startup.

Midterm Outcomes After Aortic Valve Neocuspidization (Ozaki Procedure) in Adults

BACKGROUND

Trileaflet aortic valve neocuspidization (AVN) using autologous pericardium (Ozaki procedure) is an emerging surgical treatment option for aortic valve diseases. Although excellent results have been reported from Japan, data pertaining to its use in the United States are sparse.

METHODS

All adult patients who underwent AVN (AVN group) or surgical aortic valve replacement (SAVR) with a bioprosthetic valve (SAVR group) between 2015 and 2022 were identified. Propensity score matching was used to adjust the baseline characteristics between the 2 groups.

RESULTS

A total of 101 patients underwent AVN, and 1816 patients underwent SAVR with a bioprosthetic valve. None in the AVN group required conversion to SAVR. Before matching, mean age in the AVN group was 68.5 ± 8.8 years, and 56 patients (55.4%) underwent concomitant procedures. Preoperatively, 3 (3%) had endocarditis. Bicuspid valve was observed in 38 (38.4%). None died at 30 days in the AVN group. The median follow-up duration was 3.2 years. After propensity score matching, the expected survival and freedom from at least moderate aortic regurgitation at 5 years was 91.7% ± 3.1% and 97.6% ± 1.7%, respectively. Propensity score matching yielded 77 patients in each group. The Kaplan-Meier curve demonstrated equivalent survival at 5 years between the 2 groups (P = .95). Additionally, freedom from at least moderate aortic regurgitation was comparable at 5 years (P = .23).

CONCLUSIONS

AVN can be safely performed for a variety of aortic valve diseases, with or without concomitant operations. AVN demonstrated similar midterm outcomes compared with SAVR with a bioprosthetic valve in the United States adult population.

Infectious complications following contemporary left ventricular assist device implantation

BACKGROUND

The aim of this study is to evaluate the source of infectious complications following contemporary left ventricular assist device (LVAD) implantation and to determine the impact of infections on patient outcomes.

METHODS

All patients who underwent centrifugal LVAD implantation between 2014 and 2020 at a single center were retrospectively reviewed. Postimplant infections were categorized as VAD-specific, VAD-related, or non-VAD according to previously published definitions. Postoperative survival and freedom from readmission were assessed using Kaplan-Meier analysis. Univariable and multivariable analyses were performed to determine the risk factors for postoperative infectious complications.

RESULTS

A total of 212 patients underwent centrifugal LVAD implantation (70 HeartMate 3, 142 HeartWare HVAD) during the study period. One hundred and two patients (48.1%) developed an infection, including 34 VAD-specific, 11 VAD-related, and 57 non-VAD. Staphylococcus species were the most common source of postoperative infection (n = 57, 33.7%). In multivariable analysis, diabetes significantly impacted overall postoperative infection rate. At 12 and 24 months, respectively, Kaplan-Meier survival was 81.1% and 61.6% in the infection group and 83.4% and 78.1% in the noninfection group (p = 0.006). Within the total cohort, 12- and 24-month freedom from infection were 46.2% and 31.9%, respectively. Patients with infectious complication had significantly lower rate of transplantation (16.4% vs. 43.6%; p < 0.001), increased overall mortality (46.3% vs. 17.3%, p < 0.001), and increased rates of noncardiac readmission (58.2% vs. 37.3%, p = 0.007).

CONCLUSIONS

Infections are common following contemporary LVAD implantation and are most commonly non-VAD related. Patients with postoperative infectious complications have significantly reduced rates of transplantation, survival, and freedom from noncardiac readmission.

Pre-implant right ventricular free wall strain predicts post-LVAD right heart failure

BACKGROUND

The aim of this study is to evaluate the predictive utility of preoperative right ventricular (RV) global longitudinal strain (GLS) and free wall strain (FWS) on outcomes following left ventricular assist devices (LVADs) implantation.

METHODS

Preoperative transthoracic echocardiograms were retrospectively reviewed in adults undergoing continuous-flow LVAD implantation between 2004 and 2018 at a single center. Patients undergoing pump exchange were excluded. RV GLS and FWS were calculated using commercially available software with the apical four-chamber view. The primary outcome was RV failure as defined by the Interagency Registry for Mechanically Assisted Circulatory Support within 1-year post-LVAD insertion.

RESULTS

A total of 333 patients underwent continuous-flow LVAD implantation during the study period and 137 had adequate preoperative studies for RV strain evaluation. RV FWS was found to be a significant predictor of postoperative RV failure in univariate analysis (odds ratio [OR] = 1.12, p = .03), and this finding persisted after risk adjustment in multivariable analysis (OR = 1.14, p = .04). Using the optimal cutoff value of -5.64%, the c-index of FWS in predicting RV failure was 0.65. RV GLS was not associated with post-LVAD RV failure (OR = 1.07, p = .29). PCWP was the only additional significant predictor of RV failure using multivariable analysis (OR = 0.90, p = .02).

CONCLUSION

Pre-implant RV FWS is predictive of RV failure in the first postoperative year after LVAD implantation.

Outcomes of left ventricular assist device implantation in hypercoagulable patients

BACKGROUND

The aim of this study was to evaluate outcomes of left ventricular assist devices (LVADs) in patients who tested positive for hypercoagulable hematologic disorders.

METHODS

Adults undergoing continuous-flow LVAD implantation with preoperative hypercoagulability testing between 2004 and 2018 at a single center were reviewed. Hypercoagulability was defined as testing positive for antiphospholipid antibody, anticardiolipin antibody, lupus anticoagulant, protein C, protein S, factor V Leiden, and/or heparin-induced thrombocytopenia. The primary outcome was survival on the original LVAD. Secondary outcomes included rates of thromboembolic complications and readmission for intravenous heparin treatment.

RESULTS

A total of 270 LVAD patients with pre-implant hypercoagulability testing were included, and 157 (58%) tested positive for a hypercoagulable disorder. Of those testing positive, 10 (6.4%) had a clinical pre-LVAD history of thromboembolic events. Survival was comparable between hypercoagulable and non-hypercoagulable patients (1 year: 73.3% vs 78.9%, P = .2195, 2-year: 60.7% vs 62.8%, P = .3627). Rates of pump thrombosis (14.0% vs 13.3%, P = .8618), hemolysis (4.5% vs 3.5%, P = .3536), stroke (18.5% vs 14.2%, P = .3483) and readmission for IV heparin therapy (87.3% (n = 137) vs 77.9% (n = 88), P = .7560) were similar. Outcomes were comparable in patients with positive hypercoagulable tests when stratified by pre-implant clinical history of hypercoagulability as well as stratified by recent preoperative exposure to heparin or warfarin.

CONCLUSIONS

In this series, positive laboratory tests for hypercoagulability were common amongst patients undergoing LVAD implantation although few had positive clinical histories. Survival and freedom from thromboembolic complications were comparable to non-hypercoagulable patients. Hypercoagulability alone should therefore not serve as a contraindication to LVAD implantation.

Distal Extent of Surgery for Acute Type A Aortic Dissection

Acute type A aortic dissection (TAAD) is a complex disease associated with extremely high morbidity and mortality for which we advocate a coordinated, protocol-driven system of care delivery that begins at patient diagnosis and continues throughout and beyond aortic reconstruction. Essential components of TAAD repair include prompt restoration of true lumen blood flow with obliteration of the false lumen flow, resection of the primary tear sites, restoration of valvular competency, and elimination of any organ malperfusion. This article focuses specifically on extent of repair of the aortic arch and explains our protocols regarding cannulation location and technique, cerebral and distal organ protection strategy, management of the brachiocephalic vessels, and extent of distal aortic reconstruction. We describe an operative strategy for TAAD repair that includes (1) continuous neurocerebral monitoring in all cases, (2) uninterrupted antegrade and/or retrograde cerebral perfusion (depending upon extent of arch repair) during open arch reconstruction, (3) aortic arch replacement technique with or without brachiocephalic vessel replacement using a custom trifurcate graft, and (4) descending aortic stabilization with or without the use of an elephant or frozen elephant trunk (distal stent graft). Our protocol for extent of aortic arch and brachiocephalic reconstruction has been standardized and is predicated on distinct pathoanatomic findings and/or cerebral malperfusion that are outlined.

Supraphysiologic control over HIV-1 replication mediated by CD8 T cells expressing a re-engineered CD4-based chimeric antigen receptor

HIV is adept at avoiding naturally generated T cell responses; therefore, there is a need to develop HIV-specific T cells with greater potency for use in HIV cure strategies. Starting with a CD4-based chimeric antigen receptor (CAR) that was previously used without toxicity in clinical trials, we optimized the vector backbone, promoter, HIV targeting moiety, and transmembrane and signaling domains to determine which components augmented the ability of T cells to control HIV replication. This re-engineered CAR was at least 50-fold more potent in vitro at controlling HIV replication than the original CD4 CAR, or a TCR-based approach, and substantially better than broadly neutralizing antibody-based CARs. A humanized mouse model of HIV infection demonstrated that T cells expressing optimized CARs were superior at expanding in response to antigen, protecting CD4 T cells from infection, and reducing viral loads compared to T cells expressing the original, clinical trial CAR. Moreover, in a humanized mouse model of HIV treatment, CD4 CAR T cells containing the 4-1BB costimulatory domain controlled HIV spread after ART removal better than analogous CAR T cells containing the CD28 costimulatory domain. Together, these data indicate that potent HIV-specific T cells can be generated using improved CAR design and that CAR T cells could be important components of an HIV cure strategy.

Maternal mosaicism confounds the neonatal diagnosis of type 1 Timothy syndrome

The presence of 2 distinct populations of somatic or germline cells within a single individual harboring different genotypes is termed mosaicism. Recent reports suggest that parental mosaicism is involved in the heritability of type 1 Timothy syndrome (TS1), an extremely rare and life-threatening multisystem disorder characterized by severe QT interval prolongation, syndactyly, and several other complications. Although full TS1 is caused by a single missense mutation in the CACNA1C-encoded cardiac calcium channel, mosaic TS1 parents can display isolated syndactyly without additional phenotypic manifestations. A newborn boy presented with syndactyly at birth. The presence of syndactyly in his mother led to a diagnosis of benign familial syndactyly. However, at 9 months of age, during his first syndactyly-corrective surgery, intraoperative electrocardiograms revealed extreme QT prolongation and 2:1 atrioventricular block. A comprehensive cardiac evaluation was performed, and both mother and child were tested genetically, confirming a clinical suspicion of TS1. Only the patient tested positive for the TS1 mutation; however, more extensive molecular testing revealed a limited presence of the mutation in maternally-derived DNA. This case illustrates the potential of parental mosaicism to confound the diagnosis of potentially life-threatening genetic diseases, such as TS1. Here, a mother with a partial TS1 phenotype and genetically confirmed mosaicism transmitted the TS1-causative mutation to her son, resulting in fully expressive TS1. Thus, a shared partial phenotype should not be dismissed as a benign or insignificant finding, but should be evaluated further to rule out the possibility of parental mosaicism concealing a potentially fatal heritable disease.