Papers by Allison McLarty
Multicenter evaluation of left ventricular assist device implantation with or without <scp>ECMO</scp> bridge in cardiogenic shock
Artificial organs, Mar 8, 2024
The Annals of Thoracic Surgery, Nov 1, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
208: Does an Open Chest Predict Hospital Mortality in Adult Venoarterial Ecmo?
Critical Care Medicine, Dec 15, 2022
Asaio Journal, May 1, 2017
Ventricular assist devices (VAD) became in recent years the standard of care therapy for advanced... more Ventricular assist devices (VAD) became in recent years the standard of care therapy for advanced heart failure with hemodynamic compromise. With the steadily growing population of device recipients, various post-implant complications have been reported, mostly associated with the hyper-shear generated by VADs that enhance their thrombogenicity by activating platelets. While VAD design optimization can significantly improve its thromboresistance, the implanted VAD need to be evaluated as part of a system. Several clinical studies indicated that variability in implantation configurations may contribute to the overall system thrombogenicity. Numerical simulations were conducted in the HeartAssist 5 (HA5) and HeartMate II (HMII) VADs in the following implantation configurations: (i) Inflow cannula angles -115° and 140° (HA5); (ii) three VAD circumferential orientations: 0°, 30° and 60° (HA5 and HMII); and (iii) 60° and 90° outflow graft anastomotic angles (AA) with respect to the ascending aorta (HA5). The stress accumulation of the platelets was calculated along flow trajectories and collapsed into a probability density function (PDF), representing the "thrombogenic footprint" (TF) of each configuration-a proxy to its thrombogenic potential (TP). The 140° HA5 cannula generated lower TP independent of the circumferential orientation of the VAD. 60° orientation generated the lowest TP for the HA5 versus 0° for the HMII. An AA of 60° resulted in lower TP for HA5. These results demonstrate that optimizing the implantation configuration reduces the overall system TP. Thromboresistance can be enhanced by combining VAD design optimization with the surgical implantation configurations for achieving better clinical outcomes of implanted VADs.
International Journal of Artificial Organs, Jul 12, 2019
Recurrent bleeding events are a common complication of left ventricular assist devices leading to... more Recurrent bleeding events are a common complication of left ventricular assist devices leading to significant morbidity. Clinicians may be reluctant to discontinue all antithrombotic therapies in this setting because of the risk of thrombotic events. To evaluate the safety of this strategy, we conducted a retrospective review of patients within our institution's left ventricular assist device program from February 2010 to July 2018 who had all antithrombotic therapies discontinued in response to recurrent bleeding events requiring hospitalization. Thrombotic and bleeding outcomes after discontinuation of therapy were assessed and compared. Seven patients out of 87 (8%) were identified and included in this analysis. One patient experienced pump thrombosis in the setting of driveline infection with an overall rate of thrombotic events of 0.08 per-patient-year. Sixteen gastrointestinal bleeding events occurred after discontinuation of antithrombotic therapy (1.35 per-patient-year) compared with 37 prior to discontinuation (4.28 per-patient-year) resulting in a significant reduction (reduction rate = 0.32; 95% confidence interval = [0.17, 0.58]; p < .001). Thrombotic complications were rare among patients with HeartMate II left ventricular assist device support who suffered recurrent bleeding events and in whom antithrombotic therapy was, therefore, discontinued. Gastrointestinal bleeding was significantly reduced in this group; however, angioectasia-related gastrointestinal bleedings remained problematic.
The Journal of Thoracic and Cardiovascular Surgery, Nov 1, 1993
The effects of pulmonary denervation and rejection on contractions of bronchial smooth muscle and... more The effects of pulmonary denervation and rejection on contractions of bronchial smooth muscle and epithelial modulation of these contractions were studied in dogs after denervation in right lung autotransplantation (n =6) and acute rejection after right lung aUotransplantation (n =8). Immunosuppression was withdrawn from the latter group after 5 days; rejection developed after 3 additional days. A significant (p < 0.05) increase in mean peak airway pressure occurred with rejection of aUotransplanted lungs. Rings cut from third-order bronchi of transplanted and contralateral unoperated (native) lungs in each animal were suspended in organ chambers for the measurement of isometric force. In some rings, the epithelium was removed mechanically. Acetylcholine (cholinergic neurotransmitter), serotonin (platelet-product), histamine (mast ceU product), and endothelin-l (endothelium-derived contracting factor) caused concentration-dependent contractions in all rings. In bronchi from native lungs, rings with epithelium contracted less than those without epithelium. This difference was lost after autotransplantation. The smooth muscle and epithelium were affected differendy by autotransplantation. Contractions of rings without epithelium decreased in response to acetylcholine. and endothe6n-l, whereas contractions of rings with epithelium increased in response to histamine and 5-hydroxytryptamine (p < 0.05). During acute rejection, contractions were the same as those after autotransplantation. Bronchial content of endothelin increasedfourfold with rejection. Relaxations to isoproterenol and prostaglandin E2 were similar in both groups. In conclusion, denervation reduced the ability of the smooth muscle to contract. The degree of acute pulmonary rejection seen in this study did not further affect bronchial contractions. Modulation of contractions by the bronchial epithelium was lost with both denervation and rejection. (
Journal of Heart and Lung Transplantation, Apr 1, 2018
Purpose: Operative and hemodynamic mechanisms have been implicated in right heart failure (RHF) f... more Purpose: Operative and hemodynamic mechanisms have been implicated in right heart failure (RHF) following surgical Left Ventricular Assist Device (LVAD) implantation. We investigated the effects of percutaneous LVAD (Impella, Abiomed) support on right ventricular (RV) load and adaptation acutely and during support. Methods: We reviewed all patients receiving an Impella for cardiogenic shock at our institution between July 2014 and April 2017, including only those with pre-and post-Impella invasive hemodynamic measurements. Hemodynamic data was recorded immediately prior to Impella implantation and at 12-hour intervals up to 96 hours post implantation. Results: Twenty-five patients were included. Hemodynamics are depicted in the Figure . Cardiac output increased progressively during Impella support. PAWP improved early post-Impella but did not further improve during support. Markers of RV adaptation (right ventricular stroke work index, right atrial pressure (RAP), and RAP to pulmonary artery wedge pressure ratio (RAP:PAWP)) were unchanged acutely but progressively improved during Impella support. Total RV load (effective arterial elastance; E a ) and resistive RV load (pulmonary vascular resistance (PVR)) improved progressively during support. The relationship between RV load and RV adaptation (E a /RA and E a /RAP:PAWP) was constant throughout. Median vasoactiveinotrope score declined after Impella placement, and continually declined with Impella support. Conclusion: Percutaneous LVAD support in patients with cardiogenic shock did not acutely worsen RV adaptation, in contrast to previously-described hemodynamic effects of surgically implanted LVADs. Further, RV load progressively improved during support, and the noted RV adaptation improvement during support was load-dependent as depicted by constant Ea/RA and Ea/RAP:PAWP relationships. These findings further implicate the operative changes associated with surgical LVAD implantation in early RHF following durable LVAD.
Nuclear Medicine Communications, 1993
Zenodo (CERN European Organization for Nuclear Research), Jan 10, 2022
No The activity is a systematic investigation: an activity that involves a prospective plan which... more No The activity is a systematic investigation: an activity that involves a prospective plan which incorporates data collection, either quantitative or qualitative, and data analysis to answer a question No The activity is designed to develop or contribute to generalizable knowledge: designed to draw general conclusions (i.e., knowledge gained from a study may be applied to populations outside of the specific study population) Yes. The activity meets the definition of research in the Common Rule (OHRP). Go on to the next section. No. The activity does not meet the definition of research in the Common Rule. Go to Section II -FDA Determination. 1. Indicate whether the research meets the following criteria: No The research involves living individuals No The investigator will obtain data or information about those Individuals Will the investigator (whether professional or student) obtain EITHER of the following:
Endothelium-derived factors modulate contraction of bronchial smooth muscle
American Journal of Physiology-regulatory Integrative and Comparative Physiology, May 1, 1993
Experiments were designed to determine how changes in the ratio of specific vascular endothelium-... more Experiments were designed to determine how changes in the ratio of specific vascular endothelium-derived factors might affect reactivity of bronchial smooth muscle. The epithelium was mechanically removed from rings of third-order canine bronchi, and the rings were suspended in organ chambers for measurement of isometric force. Rings of pulmonary artery were cut; in some the endothelium was mechanically removed. The arterial rings were everted and pairs, with and without endothelium, were incubated with control solution, NG-monomethyl-L-arginine (L-NMMA), indomethacin, or both L-NMMA and indomethacin for 90 min. They were then inserted into the lumen of the bronchial rings. Cumulative concentration-response curves to acetylcholine and 5-hydroxytryptamine were obtained. There was no significant difference in response between bronchi containing arteries with or without endothelium incubated with control solution. Contractions of bronchi containing arteries without endothelium, incubated in either L-NMMA or indomethacin, increased from control. However, in rings containing arteries with endothelium, incubation with either inhibitor decreased bronchial contractions. Incubation with both inhibitors eliminated the difference. These results suggest that the vascular endothelium produces factors that can both contract and relax bronchial smooth muscle. With inhibition of production of either nitric oxide with L-NMMA or prostanoids with indomethacin, release of other endothelium-derived factors occurs that attenuates contractions of bronchial smooth muscle. Therefore, an imbalance in the ratio of production of endothelium-derived factors may contribute to bronchospastic disorders.
Clinical Medicine Insights, 2015
Heart failure continues to be a significant health care problem in the United States. The inciden... more Heart failure continues to be a significant health care problem in the United States. The incidence is over 5.8 million in this country and over 23 million worldwide. The annual cost in the United States is over 39 billion dollars. Despite advanced medical therapy and the current cocktail of beta blockers, diuretics, and ACE/ARBs, the diagnosis of heart failure still carries a mortality of 39% at one year and 50% at five years, 2 rivaling many diagnoses of cancer. Once readmissions for exacerbations of heart failure recur, survival worsens. For this reason, heart transplantation was developed, and since the initial landmark transplant in 1967, with effective immunosuppression, has become the gold standard of therapy for end-stage heart failure with contemporary one-and threeyear survival of 90% and 82%. However, the number of heart transplants performed annually worldwide has plateaued at about 4,000 because of donor availability, leaving thousands at risk of dying. In addition, the average time on the waiting list for a transplant can be excessive with mortality on the waiting list up to 45%. For this reason, alternate forms of mechanical support for the failing heart have long been sought. In 1966, DeBakey reported the first successful use of a ventricular assist device (VAD) for post-cardiotomy support. The first NIH funded study was conducted in 1978. History documents the inexorable drive toward miniaturized implantable support with the first implantable VAD placed in 1991. Industry was an integral partner in product development, and in 2001, the HeartMate XVE was FDA approved as the first implantable VAD for bridge-to-transplantation (BTT). Outcomes were improved enough for the question to arise as to the applicability of the therapy to patients not eligible for transplantation. This hypothesis was tested in the prospective, randomized multicenter REMATCH trial, where HM XVE implantation was compared to optimal medical therapy for patients not considered eligible for transplant. Patients on VAD support had survival at one year increased by 50%. VADs as a form of permanent or destination therapy (DT) were approved by the FDA in 2003. Current indications for LVAD implantation as DT include patients (1) with New York Heart Classification Class 4 heart failure, (2) with optimal medical therapy for six of the past nine months, (3) with life expectancy greater than two years, and (4) not a candidate for heart transplant. This therapy was revolutionary but limited by device failure at 18 months because of failure of bearings and inflow and outflow valves. 9 This necessitated a dramatic shift in design. The concept of continuous flow pumps was conceived and developed in 1988 after a meeting of heart surgeons from Baylor College of Medicine with NASA engineers. The first human implant of the MicroMed DeBakey Noon VAD was in Germany in 1998, which was the first continuous flow VAD in man. Early concerns about the human physiology being incompatible with lack of pulsatility were laid to rest as first
The Journal of Thoracic and Cardiovascular Surgery, May 1, 2019
Impact of Acute Pulmonary Rejection on Cardiac Function
Circulation, 1995
BackgroundExperiments were designed to define cardiac function in dogs with single lung allograft... more BackgroundExperiments were designed to define cardiac function in dogs with single lung allografts during acute rejection of the allografted lung.Methods and ResultsLeft lungs were either autotransplanted (n=4) or allotransplanted (n=8) in adult male mongrel dogs. All allotransplanted animals were maintained on triple-drug immunosuppression (cyclosporine, azathioprine, and steroids) for 5 days after the operation. In 4 allotransplanted animals, treatment was discontinued, allowing the animals to reject (usually after a further 3 days; rejecting group); 4 other allotransplanted animals were maintained on immunosuppression for an additional 3 days (immunosuppressed group). Another group of dogs were not operated on but were maintained on the same immunosuppression as the rejecting group (controls). All experimental animals underwent fast computed tomographic scanning with measurement of left ventricular pressure and calculation of ventricular chamber volumes, cross-sectional areas of coronary arteries, myocardial perfusion, and intramyocardial blood volume. Neither cardiac output, left ventricular mass, left ventricular pressure, nor myocardial oxygen consumption was altered during acute rejection of lung allografts. However, left ventricular contractility (systolic elastance, Emax) and ejection fraction were depressed to approximately one half (P&lt;.05) in acutely rejecting animals compared with other groups. The cross-sectional area of the coronary arteries was less in autotransplanted and allotransplanted treated animals than in animals that were not operated on. Cross-sectional area of the coronary arteries was decreased by an additional 30% in the rejecting group (P&lt;.05).ConclusionsThe results of this study indicate that acute rejection of a single lung allograft decreases cardiac performance and reduces diameter of coronary arteries in the recipient. Alterations of circulating humoral factors and activated leukocytes may contribute to these changes.
208: Does an Open Chest Predict Hospital Mortality in Adult Venoarterial Ecmo?
Critical Care Medicine
Lung Cancer in Nonsmokers- a Risk Factor Analysis
A110. LUNG CANCER RISK, SCREENING, TREATMENT, AND OUTCOMES
SAVE score with lactate modification predicts in-hospital mortality in patients with ongoing cardiac arrest during VA-ECMO cannulation
The International Journal of Artificial Organs, 2021
The survival after veno-arterial extracorporeal membrane oxygenation score and its lactate modifi... more The survival after veno-arterial extracorporeal membrane oxygenation score and its lactate modification predict in-hospital mortality in patients based on pre-extracorporeal membrane oxygenation variables. Cardiac arrest history is a significant variable in these scores; however, patients with ongoing cardiac arrest during cannulation were excluded from these models. The goal of this study is to validate the survival after veno-arterial extracorporeal membrane oxygenation score with a lactate modification among patients with ongoing cardiac arrest. In our study, the survival after veno-arterial extracorporeal membrane oxygenation score predicted mortality in all patients, but did so with higher discrimination among ongoing cardiac arrest patients with a lactate modification.
JTCVS open, Mar 1, 2022
Objective: The changing surgical education landscape in surgical training pathways greatly dimini... more Objective: The changing surgical education landscape in surgical training pathways greatly diminished cardiac surgical knowledge, interest, and skills among general surgery trainees. To address this issue, our department developed a cardiac surgery simulation program. Methods: All simulation sessions lasted at least 2 hours and occurred during resident physician protected education time. Participants were postgraduate year 2 through 5 general surgery residents assisted by staff and led by cardiac surgery faculty. Five of the 6 sessions were porcine heart wet labs simulating coronary anastomoses, surgical aortic valve replacement, mitral valve repair and replacement, and left ventricular assist device implantation. The transcatheter aortic valve replacement session was designed as a video simulation and a manikin for wire manipulation and implantation. At the end of each lab, all participants were surveyed about their experiences. Results: An average of 10 resident physicians participated in each session (range, 8-13), for a total of 120 simulation hours. One hundred percent of residents surveyed agreed that the labs improved knowledge and understanding of the disease process, improved understanding of cardiac surgical principles, and helped acquire skills for surgical residency and treatment. Factors that residents cited for increased attendance rate included protected education time, hands-on experience, and a high faculty-to-resident ratio. Conclusions: This program successfully demonstrates that cardiac surgery training and simulation can be integrated into general surgery residency programs, despite the lack of cardiac surgery requirements. Additional metrics for future study includes technical grades on resident physicians' performance to further assess the value of this program. (JTCVS Open 2022;9:179-84) Example of simulation session with 2:1 resident-tofaculty ratio. Cardiac surgery simulation can be integrated into general surgery residency programs. This is important to drive general surgery resident interest in pursuing a cardiac surgery career.
A literature review: pre-/post-operative atrial fibrillation for thoracic aortic aneurysm procedures
Vessel plus, 2022
Atrial fibrillation (AF) is among the most frequent cardiac surgical arrhythmias documented. The ... more Atrial fibrillation (AF) is among the most frequent cardiac surgical arrhythmias documented. The global AF prevalence is estimated at over 33 million cases, with estimates ranging up to 6.1 million cases in the United States. Among cardiac surgical patients, the risk factors for new-onset post-operative AF (POAF) include Caucasian race with increased prevalence documented in older men. Due to trends of earlier thoracic aortic aneurysm (TAA) detection and treatment, it is timely to review the AF association with adverse TAA clinical outcomes. Towards this goal, a comprehensive PubMed literature review was performed. For this initial Medline literature search, the MeSH search strategy included “thoracic aortic aneurysm” and “atrial fibrillation”. Based on the pertinent articles identified, the limited literature available for preoperative TAA AF and the predictors of POAF following TAA procedures were reviewed. Given only a handful of publications addressing these pre-/post-operative AF topics were identified using this very broad initial search approach, a knowledge chasm exists–as very little is known about TAA patients with pre-operative or new-onset post-operative AF. Given the paucity of evidence-based information available, clinically relevant TAA-specific research questions have been raised to guide future TAA AF-related investigations.
Clinical Medicine Insights, 2015
Introductory Editorial - Heart Failure: An Exploration of Recent Advances in Research and Treatment (A)
DOAJ (DOAJ: Directory of Open Access Journals), Oct 1, 2015
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Papers by Allison McLarty