William E Cohn

Baylor College of Medicine, Houston, Texas, United States

Are you William E Cohn?

Claim your profile

Publications (148)460.86 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: For more than 30 years, heart transplantation has been a successful therapy for patients with terminal heart failure. Mechanical circulatory support (MCS) was developed as a therapy for end-stage heart failure at a time when cardiac transplantation was not yet a useful treatment modality. With the more successful outcomes of cardiac transplantation in the 1980s, MCS was applied as a bridge to transplantation. Because of donor scarcity and limited long-term survival, heart transplantation has had a trivial impact on the epidemiology of heart failure. Surgical implementation of MCS, both for short- and long-term treatment, affords physicians an opportunity for dramatic expansion of a meaningful therapy for these otherwise mortally ill patients. This review explores the evolution of mechanical circulatory support and its potential for providing long-term therapy, which may address the limitations of cardiac transplantation.
    11/2015; 2015(3):1-11. DOI:10.1155/2015/849571
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Retained blood occurs when drainage systems fail to adequately evacuate blood during recovery from cardiothoracic surgery. As a result, a spectrum of mechanical and inflammatory complications can ensue in the acute, subacute, and chronic setting. The objectives of this review were to define the clinical syndrome associated with retained blood over the spectrum of recovery and to review existing literature regarding how this may lead to complications and contributes to poor outcomes. To better understand and prevent this constellation of clinical complications, a literature review was conducted, which led us to create a new label that better defines the clinical entity we have titled retained blood syndrome. Analysis of published reports revealed that 13.8% to 22.7% of cardiac surgical patients develop one or more components of retained blood syndrome. This can present in the acute, subacute, or chronic setting, with different pathophysiologic mechanisms active at different times. The development of retained blood syndrome has been linked to other clinical outcomes, including the development of postoperative atrial fibrillation and infection and the need for hospital readmission. Grouping multiple objectively measurable and potentially preventable postoperative complications that share a common etiology of retained blood over the continuum of recovery demonstrates a high prevalence of retained blood syndrome. This suggests the need to develop, implement, and test clinical strategies to enhance surgical drainage and reduce postoperative complications in patients undergoing cardiothoracic surgery.
    Innovations Technology and Techniques in Cardiothoracic and Vascular Surgery 11/2015; 10(5):296-303. DOI:10.1097/IMI.0000000000000200
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective: Ventricular reconditioning and device weaning in select patients with continuous-flow left ventricular assist devices (CF LVADs) has been shown to be feasible. However, little is known regarding the outcomes associated with different surgical methods of device removal. We examined the effect of surgical explantation approach on early and late outcomes. Methods: We retrospectively reviewed data from all patients who underwent successful ventricular weaning and CF LVAD explantation at our center. Patients were stratified by surgical approach. Descriptive univariate statistics, multivariate regression, and survival analyses were performed. Patients were censored by transplant, device reimplantation, or end of follow-up. Results: Twenty-seven patients were identified who underwent successful removal of a CF LVAD (25 HeartMate II, 2 HeartWare) after 532 ± 424 days of support (range, 42-1937 days). Four approaches were used that vary primarily in the degree of retained pump material: complete pump removal with plug ventriculotomy closure (n = 13; 48%), pump housing explant with ligation of the inflow and outflow grafts (n = 7; 26%), ligation of the outflow graft and driveline transection (n = 5; 19%), and driveline transection alone (n = 2; 7%). Mean overall postexplant survival was 1286 ± 947 days (range, 143-3072 days). Overall time-to-event and survival analyses showed no significant association between surgical approach and postoperative length of stay (P = .7), stroke (P = .12), reoperation (P = .4), or survival (P = .12). Conclusions: For patients who receive device therapy, pump deactivation and removal represents a favorable outcome. All methods are feasible and produce similar early and late survival and clinical outcomes.
    The Journal of thoracic and cardiovascular surgery 09/2015; DOI:10.1016/j.jtcvs.2015.08.024 · 4.17 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: IntroductionPatients undergoing catheter ablation for ventricular tachycardia (VT) may require epicardial mapping. In patients with end stage heart failure, hybrid surgical epicardial mapping and ablation during the period of left ventricular assist device (LVAD) implantation may be considered in select patients to reduce post-LVAD ventricular tachycardia.Methods and ResultsFrom March 2009 through October 2012, 5 patients (4 men and 1 woman, age range 52–73yrs) underwent open chest electrophysiology study and epicardial mapping for recurrent ventricular tachycardia while the heart was exposed during the period of LVAD implantation. Epicardial mapping was considered if patients had recurrent VT despite failed prior endocardial ablation and/or EKG features of an epicardial exit. Activation and/or a substrate mapping approach were employed during all procedures. Three of 5 patients (60%) had acute procedural success. In all patients, VT was either eliminated or significantly reduced with epicardial ablation. One patient had mediastinal bleeding delaying sternal closure. During a follow-up period of 363±368 days, 4 patients died due to non-arrhythmic causes.Conclusions Open-chest hybrid epicardial mapping and ablation for recurrent VT is feasible and can be considered in select patients during the period of LVAD implantation.This article is protected by copyright. All rights reserved
    Journal of Cardiovascular Electrophysiology 09/2015; DOI:10.1111/jce.12839 · 2.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Introduction: In the setting of increasingly complex medical therapies and limited physician resources, the recent emergence of 'smart' technology offers tremendous potential for improved logistics, efficiency, and communication between medical team members. In an effort to harness these capabilities, we sought to evaluate the utility of this technology in surgical practice through the employment of a wearable camera device during cardiothoracic organ recovery. Methods: A single procurement surgeon was trained for use of an Explorer Edition Google Glass™ (Google Inc., Mountain View, CA) during the recovery process. Live video feed of each procedure was securely broadcast to allow for members of the home transplant team to remotely participate in organ assessment. Primary outcomes involved demonstration of technological feasibility and validation of quality assurance through group assessment. Results: The device was employed for the recovery of four organs: a right single lung, a left single lung, and two bilateral lung harvests. Live video of the visualization process was remotely accessed by the home transplant team, and supplemented final verification of organ quality. In each case, the organs were accepted for transplant without disruption of standard procurement protocols. Media files generated during the procedures were stored in a secure drive for future documentation, evaluation, and education purposes without preservation of patient identifiers. Conclusions: Live video streaming can improve quality assurance measures by allowing off-site members of the transplant team to participate in the final assessment of donor organ quality. While further studies are needed, this project suggests that the application of mobile 'smart' technology offers not just immediate value, but the potential to transform our approach to the practice of medicine.
    World Journal of Surgery 08/2015; DOI:10.1007/s00268-015-3235-x · 2.64 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We tested the short-term effects of completely nonpulsatile versus pulsatile circulation after ventricular excision and replacement with total implantable pumps in an animal model on peripheral vascular permeability. Ten calves underwent cardiac replacement with two HeartMate III continuous-flow rotary pumps. In five calves, the pump speed was rapidly modulated to impart a low-frequency pulse pressure in the physiologic range (10-25 mm Hg) at a rate of 40 pulses per minute (PP). The remaining five calves were supported with a pulseless systemic circulation and no modulation of pump speed (NP). Skeletal muscle biopsies were obtained before cardiac replacement (baseline) and on postoperative days (PODs) 1, 7, and 14. Skeletal muscle-tissue water content was measured, and morphologic alterations of skeletal muscle were assessed. VE-cadherin, phospho-VE-cadherin, and CD31 were analyzed by immunohistochemistry. There were no significant changes in tissue water content and skeletal muscle morphology within group or between groups at baseline, PODs 1, 7, and 14, respectively. There were no significant alterations in the expression and/or distribution of VE-cadherin, phospho-VE-cadherin, and CD31 in skeletal muscle vasculature at baseline, PODs 1, 7, and 14 within each group or between the two groups, respectively. Although continuous-flow total artificial heart (CFTAH) with or without a pulse pressure caused slight increase in tissue water content and histologic damage scores at PODs 7 and 14, it failed to reach statistical significance. There was no significant adherens-junction protein degradation and phosphorylation in calf skeletal muscle microvasculature after CFTAH implantation, suggesting that short term of CFTAH with or without pulse pressure did not cause peripheral endothelial injury and did not increase the peripheral microvascular permeability. Copyright © 2015 Elsevier Inc. All rights reserved.
    Journal of Surgical Research 06/2015; DOI:10.1016/j.jss.2015.06.035 · 1.94 Impact Factor
  • William E Cohn · Daniel L Timms · O H Frazier ·
    [Show abstract] [Hide abstract]
    ABSTRACT: A practical artificial heart has been sought for >50 years. An increasing number of people succumb to heart disease each year, but the number of hearts available for transplantation remains small. Early total artificial hearts mimicked the pumping action of the native heart. These positive-displacement pumps could provide adequate haemodynamic support and maintain the human circulation for short periods, but large size and limited durability adversely affected recipients' quality of life. Subsequent research into left ventricular assist devices led to the use of continuous-flow blood pumps with rotating impellers. Researchers have attempted to integrate this technology into modern total artificial hearts with moderate clinical success. The importance of pulsatile circulation remains unclear. Future research is, therefore, needed into positive-displacement and rotary total artificial hearts.
    Nature Reviews Cardiology 06/2015; 12(10). DOI:10.1038/nrcardio.2015.79 · 9.18 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Arteriovenous fistulae (AVFs) created by conventional surgical techniques are associated with suboptimal short- and long-term patency. This study investigated the feasibility of creating fistulae with a percutaneous system and evaluated the utility of percutaneous AVFs (pAVFs) in providing hemodialysis access. From August 2012 to September 2013, a percutaneous system was used to attempt pAVF creation between the proximal ulnar artery and a closely associated ulnar vein in 33 patients. Technical success, adverse events, and time to pAVF maturity were recorded, as was clinical effectiveness at 6 months. A pAVF was successfully created in 32 of 33 patients (97%). Four patients died during the follow-up period from causes unrelated to the procedure; one patient was lost to follow-up. Of the remaining 27 patients, 24 were undergoing successful dialysis via their pAVF at 6 months. Two additional patients had usable access but did not initiate dialysis during the study. One spontaneous pAVF thrombosis occurred in a patient with preexisting central vein stenosis. Cumulative pAVF patency at 6 months was 96.2% (26 of 27; standard error, 3.8%). Mean time to pAVF maturation was 58 days (range, 37-168 d). There was one serious procedure-related adverse event and five minor procedure-related adverse events. Although larger studies are required to validate efficacy in a wide range of patients, this study demonstrates hemodialysis access successfully created with an endovascular catheter-based system. Patency of pAVFs and time to maturation were superior to published results of surgical techniques. Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.
    Journal of vascular and interventional radiology: JVIR 04/2015; 26(4). DOI:10.1016/j.jvir.2014.12.018 · 2.41 Impact Factor

  • The Journal of Heart and Lung Transplantation 04/2015; 34(4):S24-S25. DOI:10.1016/j.healun.2015.01.055 · 6.65 Impact Factor

  • The Journal of Heart and Lung Transplantation 04/2015; 34(4):S248. DOI:10.1016/j.healun.2015.01.688 · 6.65 Impact Factor

  • The Journal of Heart and Lung Transplantation 04/2015; 34(4):S41-S42. DOI:10.1016/j.healun.2015.01.099 · 6.65 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cardiac surgical procedures carry a high risk of perioperative bleeding. Surgical sealants are often used to prevent suture line bleeding. PreveLeak™ is a surgical sealant composed of bovine serum albumin, a polyaldehyde cross-linker, and other components that forms a soft, flexible, water-tight, mechanical seal that is biocompatible and bioresorbable. A prospective, multicentre study evaluated PreveLeak use in 44 subjects undergoing 63 cardiac procedures, primarily coronary artery bypass grafting (n = 23/63, 36.5%) and aortic valve replacement (n = 19/63, 30.2%). PreveLeak was applied to 127 suture lines and the time to sealing evaluated upon clamp release. The primary safety endpoint was the incidence of significant bleeding, infections, neurological deficits and immune/inflammatory allergic responses within 6 weeks post-treatment; subjects were followed for 3 months. Immediate sealing was achieved at all sites in 42 of 44 subjects (95.5%) and 125 of 127 treatment sites (98.4%). There were nine primary safety events: eight infections and one transient neurological deficit. Most adverse events were mild (n = 46/71, 64.8%) or moderate (n = 18/71, 25.4%) in severity. One adverse event (transient vasospasm) was considered possibly sealant-related. One death occurred due to a cardiac arrest. PreveLeak prevented bleeding at 98.4% of treated sites and was well tolerated; adverse events were consistent with those commonly observed in subjects undergoing surgical procedures. These results compared favourably with published studies of other sealants. The observed prevention of bleeding is clinically important in cardiac surgical patients. A randomized, comparative study is justified to further evaluate PreveLeak and confirm the findings from this study. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
    Interactive Cardiovascular and Thoracic Surgery 03/2015; 20(6). DOI:10.1093/icvts/ivv061 · 1.16 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background The potential for myocardial reconditioning and device explantation after long-term continuous-flow LVAD support presents an opportunity to delay or avoid transplantation in select patients. Methods Thirty patients (of 811) with end-stage heart failure supported with continuous-flow LVADs were assessed for device explantation. Each patient underwent an individualized process of weaning focused on principles of ventricular unloading, gradual reconditioning, and transition to medical therapy. Results After varying reconditioning periods, 27 patients underwent LVAD explant (16 men, 11 women; age, 39±12 years). Three patients were evaluated for explantation but could not be weaned (2 men, 1 woman; age 22±6 years). The duration of LVAD support was 533±424 days (42–1937) for the explant cohort and 1097±424 days (643–1483) for the non-explant cohort. Left ventricular end diastolic dimension, LV ejection fraction, systolic pulmonary artery pressure, cardiac output, and cardiac index in the explant cohort were significantly improved at explantation (all, p<0.05). Two late deaths occurred after LVAD explantation despite satisfactory native cardiac function, and 1 patient required resumption of LVAD support 2.7 years after device removal. The remaining explant patients remain in NYHA classes I-II with medical management alone (mean survival post-explant, 1172±948 days). All 3 candidates who could not be weaned were ultimately transplanted. Conclusions The potential for recovery of native left ventricular function after long-term continouous-flow LVAD support should encourage a more aggressive approach to ventricular reconditioning with the goal of device explantation and a return to medical management, particularly in young patients with dilated cardiomyopathy.
    The Journal of Heart and Lung Transplantation 09/2014; 34(6). DOI:10.1016/j.healun.2014.09.015 · 6.65 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective Although the development of continuous flow ventricular assist devices (CF-VAD) has improved VAD reliability, VAD exchange is still occasionally necessary. The focus of this study was to analyze our institution’s entire experience with primary CF-VAD implants, evaluate baseline variables, determine which factors predict the need for exchange, and evaluate the impact of exchange on survival and event-free survival. Methods We retrospectively reviewed the data of all patients in a single center who received a primary CF-VAD implant between December 1999 and December 2013. All CF-VAD exchanges were reviewed; demographics, indications, pre-operative and operative data, and clinical outcomes were summarized. Univariate and multivariable regression analyses were performed to ascertain predictors for exchange. Time-to-event and survival analyses were also performed. Results We identified 469 patients who underwent 546 CF-VAD implantations. Of these patients, 66 (14%) underwent 77 exchanges from one CF-VAD to another. The primary indications included hemolysis or thrombosis (n=49; 63,6%), infection (n=9; 11.7%), or other causes (n=19; 24.7%). Survival was not significantly different between exchange and non-exchange groups. Multivariable regression analysis identified a history of cerebrovascular events as a significant predictor for exchange. Among exchange patients, 11 underwent heart transplantation, 3 had their CF-VADs explanted, 26 had ongoing support, and 26 died during device support. Conclusions In our series of contemporary CF-VAD exchanges, history of prior cerebrovascular events was a significant predictor for exchange. Exchange did not impact early or late survival. Our data suggest aggressive surgical treatment of pump-related complications with exchange is safe and justified.
    Journal of Thoracic and Cardiovascular Surgery 09/2014; 149(1). DOI:10.1016/j.jtcvs.2014.08.054 · 4.17 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Rotary blood pumps are emerging as a viable technology for total artificial hearts, and the development of physiological control algorithms is accelerated with new evaluation environments. In this article, we present a novel hybrid mock circulation loop (HMCL) designed specifically for evaluation of rotary total artificial hearts (rTAH). The rTAH is operated in the physical domain while all vasculature elements are embedded in the numerical domain, thus combining the strengths of both approaches: fast and easy exchange of the vasculature model together with improved controllability of the pump. Parameters, such as vascular resistance, compliance, and blood volume, can be varied dynamically in silico during operation. A hydraulic–numeric interface creates a real-time feedback loop between the physical and numerical domains. The HMCL uses computer-controlled resistance valves as actuators, thereby reducing the size and number of hydraulic elements. Experimental results demonstrate a stable interaction over a wide operational range and a high degree of flexibility. Therefore, we demonstrate that the newly created design environment can play an integral part in the hydraulic design, control development, and durability testing of rTAHs.
    Artificial Organs 09/2014; 38(9). DOI:10.1111/aor.12380 · 2.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although there is limited consensus about the strict requirement to deliver pulsatile perfusion to the human circulatory system, speed modulation of rotary blood pumps is an approach that may capture the benefits of both positive displacement and continuous flow blood pumps. In the current stage of development of the BiVACOR Total Artificial Heart emphasis is placed on providing pulsatile outflow from the pump. Multiple pulsatile speed profiles have been applied in preliminary in-vivo operation in order to assess the capability of the TAH to recreate a physiologic pulse. This paper provides an overview about recent research towards pulsatile BiVACOR operation with special emphasis on motor and control requirements and developments.
  • Holley C Love · Daniel L Timms · Frank Nestler · O H Frazier · William E Cohn ·
    [Show abstract] [Hide abstract]
    ABSTRACT: A mock circulatory loop was constructed to facilitate total artificial heart development. The loop includes many novel features such as a pressure-regulated tank to simulate exercise conditions, controllable systemic and pulmonary vascular resistance to create left-right flow imbalances as seen in postural change and breathing, and a left atrial suction valve. Dual HeartMate II pumps and the BiVACOR® rotary total artificial heart were used to generate pressure and flow data characterizing the flow loop.
  • Hari R Mallidi · Jatin Anand · William E Cohn ·
    [Show abstract] [Hide abstract]
    ABSTRACT: Mechanical circulatory support of the failing heart has become an important means of treating end-stage heart disease. This rapidly growing therapeutic field has produced impressive clinical outcomes and has great potential to help thousands of otherwise terminal patients worldwide. In this review, we examine the state of the art of mechanical circulatory support: current practice, totally implantable systems of the future, evolving biventricular support mechanisms, the potential for myocardial recovery and adjunctive treatment methods, and miniaturized devices with expanded indications for therapy.
    Texas Heart Institute journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital 04/2014; 41(2):115-20. DOI:10.14503/THIJ-14-4143 · 0.65 Impact Factor

  • The Journal of Heart and Lung Transplantation 04/2014; 33(4):S204. DOI:10.1016/j.healun.2014.01.891 · 6.65 Impact Factor

  • The Journal of Heart and Lung Transplantation 04/2014; 33(4):S237-S238. DOI:10.1016/j.healun.2014.01.913 · 6.65 Impact Factor

Publication Stats

1k Citations
460.86 Total Impact Points


  • 2010-2015
    • Baylor College of Medicine
      • Department of Surgery
      Houston, Texas, United States
  • 2004-2015
    • Texas Heart Institute
      • Division of Cardiovascular Surgery
      Houston, Texas, United States
  • 2014
    • St. Luke's Episcopal Health System
      Houston, Texas, United States
  • 2007-2013
    • St. John's Episcopal Hospital
      Rockaway, New Jersey, United States
  • 2008-2011
    • Houston Methodist Hospital
      Houston, Texas, United States
    • University of Cincinnati
      Cincinnati, Ohio, United States
  • 2009
    • St. Luke School of Medicine
      Houston, Texas, United States
  • 2008-2009
    • University of Houston
      • Department of Mechanical Engineering
      Houston, Texas, United States
  • 1997-2003
    • Beth Israel Deaconess Medical Center
      • Department of Surgery
      Boston, Massachusetts, United States
  • 1995-2003
    • Harvard Medical School
      • Department of Medicine
      Boston, Massachusetts, United States
  • 2000
    • Rhode Island Hospital
      Providence, Rhode Island, United States