Mario Gaudino, Gianni D Angelini, Charalambos Antoniades, Faisal Bakaeen, Umberto Benedetto, Antonio M Calafiore, Antonino Di Franco, Michele Di Mauro, Stephen E Fremes, Leonard N Girardi, David Glineur, Juan Grau, Guo-Wei He, Carlo Patrono, John D Puskas, Marc Ruel, Thomas A Schwann, Derrick Y Tam, James Tatoulis, Robert Tranbaugh, Michael Vallely, Marco A Zenati, Michael Mack, and David P Taggart. 2018. “Off-Pump Coronary Artery Bypass Grafting: 30 Years of Debate.” J Am Heart Assoc, 7, 16, Pp. e009934.
George S Avrunin, Stefan C Christov, Lori A Clarke, Heather M Conboy, Leon J Osterweil, and Marco A Zenati. 2018. “Process Driven Guidance for Complex Surgical Procedures.” AMIA Annu Symp Proc, 2018, Pp. 175-184.Abstract
Surgical team processes are known to be complex and error prone. This paper describes an approach that uses a detailed, validated model of a medical process to provide the clinicians who carry out that complex process with offline and online guidance to help reduce errors. Offline guidance is in the form of a hypertext document describing all the ways the process can be carried out. Online guidance is in the form of a context-sensitive and continually updated electronic "checklist" that lists next steps and needed resources, as well as completed steps. In earlier work, we focused on providing such guidance for single-clinician or single-team processes. This paper describes guiding the collaboration of multiple teams of clinicians through complex processes with significant concurrency, complicated exception handling, and precise and timely communication. We illustrate this approach by applying it to a highly complex, high risk subprocess of cardiac surgery.
Marco A Zenati and Deepak L Bhatt. 2018. “Real-world revascularization therapy in heart failure: It's a jungle out there!” J Thorac Cardiovasc Surg, 156, 4, Pp. 1422-1423.
RD Dias, MC Ngo-Howard, MT Boskovski, MA Zenati, and SJ Yule. 2018. “Systematic review of measurement tools to assess surgeons' intraoperative cognitive workload.” Br J Surg, 105, 5, Pp. 491-501.Abstract
BACKGROUND: Surgeons in the operating theatre deal constantly with high-demand tasks that require simultaneous processing of a large amount of information. In certain situations, high cognitive load occurs, which may impact negatively on a surgeon's performance. This systematic review aims to provide a comprehensive understanding of the different methods used to assess surgeons' cognitive load, and a critique of the reliability and validity of current assessment metrics. METHODS: A search strategy encompassing MEDLINE, Embase, Web of Science, PsycINFO, ACM Digital Library, IEEE Xplore, PROSPERO and the Cochrane database was developed to identify peer-reviewed articles published from inception to November 2016. Quality was assessed by using the Medical Education Research Study Quality Instrument (MERSQI). A summary table was created to describe study design, setting, specialty, participants, cognitive load measures and MERSQI score. RESULTS: Of 391 articles retrieved, 84 met the inclusion criteria, totalling 2053 unique participants. Most studies were carried out in a simulated setting (59 studies, 70 per cent). Sixty studies (71 per cent) used self-reporting methods, of which the NASA Task Load Index (NASA-TLX) was the most commonly applied tool (44 studies, 52 per cent). Heart rate variability analysis was the most used real-time method (11 studies, 13 per cent). CONCLUSION: Self-report instruments are valuable when the aim is to assess the overall cognitive load in different surgical procedures and assess learning curves within competence-based surgical education. When the aim is to assess cognitive load related to specific operative stages, real-time tools should be used, as they allow capture of cognitive load fluctuation. A combination of both subjective and objective methods might provide optimal measurement of surgeons' cognition.
George S Avrunin, Lori A Clarke, Heather M Conboy, Leon J Osterweil, Roger D Dias, Steven J Yule, Julian M Goldman, and Marco A Zenati. 2018. “Toward Improving Surgical Outcomes by Incorporating Cognitive Load Measurement into Process-Driven Guidance.” Softw Eng Healthc Syst SEHS IEEE ACM Int Workshop, 2018, Pp. 2-9.Abstract
This paper summarizes the accomplishments and recent directions of our medical safety project. Our process-based approach uses a detailed, rigorously-defined, and carefully validated process model to provide a dynamically updated, context-aware and thus, "Smart" Checklist to help process performers understand and manage their pending tasks [7]. This paper focuses on support for teams of performers, working independently as well as in close collaboration, in stressful situations that are life critical. Our recent work has three main thrusts: provide effective real-time guidance for closely collaborating teams; develop and evaluate techniques for measuring cognitive load based on biometric observations and human surveys; and, using these measurements plus analysis and discrete event process simulation, predict cognitive load throughout the process model and propose process modifications to help performers better manage high cognitive load situations. This project is a collaboration among software engineers, surgical team members, human factors researchers, and medical equipment instrumentation experts. Experimental prototype capabilities are being built and evaluated based upon process models of two cardiovascular surgery processes, Aortic Valve Replacement (AVR) and Coronary Artery Bypass Grafting (CABG). In this paper we describe our approach for each of the three research thrusts by illustrating our work for heparinization, a common subprocess of both AVR and CABG. Heparinization is a high-risk error-prone procedure that involves complex team interactions and thus highlights the importance of this work for improving patient outcomes.
Heather M Conboy, George S Avrunin, Lori A Clarke, Leon J Osterweil, Stefan C Christov, Julian M Goldman, Steven J Yule, and Marco A Zenati. 2017. “Cognitive Support During High-Consequence Episodes of Care in Cardiovascular Surgery.” IEEE Int Interdiscip Conf Cogn Methods Situat Aware Decis Support, 2017.Abstract
Despite significant efforts to reduce preventable adverse events in medical processes, such events continue to occur at unacceptable rates. This paper describes a computer science approach that uses formal process modeling to provide situationally aware monitoring and management support to medical professionals performing complex processes. These process models represent both normative and non-normative situations, and are validated by rigorous automated techniques such as model checking and fault tree analysis, in addition to careful review by experts. Context-aware Smart Checklists are then generated from the models, providing cognitive support during high-consequence surgical episodes. The approach is illustrated with a case study in cardiovascular surgery.
Nathan A Wood, David Schwartzman, Marco A Zenati, and Cameron N Riviere. 2017. “Physiological motion modeling for organ-mounted robots.” Int J Med Robot, 13, 4.Abstract
BACKGROUND: Organ-mounted robots passively compensate heartbeat and respiratory motion. In model-guided procedures, this motion can be a significant source of information that can be used to aid in localization or to add dynamic information to static preoperative maps. METHODS: Models for estimating periodic motion are proposed for both position and orientation. These models are then tested on animal data and optimal orders are identified. Finally, methods for online identification are demonstrated. RESULTS: Models using exponential coordinates and Euler-angle parameterizations are as accurate as models using quaternion representations, yet require a quarter fewer parameters. Models which incorporate more than four cardiac or three respiration harmonics are no more accurate. Finally, online methods estimate model parameters as accurately as offline methods within three respiration cycles. CONCLUSIONS: These methods provide a complete framework for accurately modelling the periodic deformation of points anywhere on the surface of the heart in a closed chest.
Christopher L Tarola, Jacquelyn A Quin, Miguel E Haime, Jennifer M Gabany, Kristin B Taylor, Kay B Leissner, and Marco A Zenati. 2016. “Computer-Assisted Process Modeling to Enhance Intraoperative Safety in Cardiac Surgery.” JAMA Surg, 151, 12, Pp. 1183-1186.
Yang Zhu, Nathan A Wood, Kevin Fok, Tomo Yoshizumi, Dae Woo Park, Hongbin Jiang, David S Schwartzman, Marco A Zenati, Takafumi Uchibori, William R Wagner, and Cameron N Riviere. 2016. “Design of a Coupled Thermoresponsive Hydrogel and Robotic System for Postinfarct Biomaterial Injection Therapy.” Ann Thorac Surg, 102, 3, Pp. 780-786.Abstract
BACKGROUND: In preclinical testing, ventricular wall injection of hydrogels has been shown to be effective in modulating ventricular remodeling and preserving cardiac function. For some approaches, early-stage clinical trials are under way. The hydrogel delivery method varies, with minimally invasive approaches being preferred. Endocardial injections carry a risk of hydrogel regurgitation into the circulation, and precise injection patterning is a challenge. An epicardial approach with a thermally gelling hydrogel through the subxiphoid pathway overcomes these disadvantages. METHODS: A relatively stiff, thermally responsive, injectable hydrogel based on N-isopropylacrylamide and N-vinylpyrrolidone (VP gel) was synthesized and characterized. VP gel thermal behavior was tuned to couple with a transepicardial injection robot, incorporating a cooling feature to achieve injectability. Ventricular wall injections of the optimized VP gel have been performed ex vivo and on beating porcine hearts. RESULTS: Thermal transition temperature, viscosity, and gelling time for the VP gel were manipulated by altering N-vinylpyrrolidone content. The target parameters for cooling in the robotic system were chosen by thermal modeling to support smooth, repeated injections on an ex vivo heart. Injections at predefined locations and depth were confirmed in an infarcted porcine model. CONCLUSIONS: A coupled thermoresponsive hydrogel and robotic injection system incorporating a temperature-controlled injectate line was capable of targeted injections and amenable to use with a subxiphoid transepicardial approach for hydrogel injection after myocardial infarction. The confirmation of precise location and depth injections would facilitate a patient-specific planning strategy to optimize injection patterning to maximize the mechanical benefits of hydrogel placement.
Nahid Saberi, Mohsen Mahvash, and Marco Zenati. 2015. “An artificial system for selecting the optimal surgical team.” Annu Int Conf IEEE Eng Med Biol Soc, 2015, Pp. 218-21.Abstract
We introduce an intelligent system to optimize a team composition based on the team's historical outcomes and apply this system to compose a surgical team. The system relies on a record of the procedures performed in the past. The optimal team composition is the one with the lowest probability of unfavorable outcome. We use the theory of probability and the inclusion exclusion principle to model the probability of team outcome for a given composition. A probability value is assigned to each person of database and the probability of a team composition is calculated from them. The model allows to determine the probability of all possible team compositions even if there is no recoded procedure for some team compositions. From an analytical perspective, assembling an optimal team is equivalent to minimizing the overlap of team members who have a recurring tendency to be involved with procedures of unfavorable results. A conceptual example shows the accuracy of the proposed system on obtaining the optimal team.
Marco A Zenati, Michael J Gaziano, Joseph F Collins, Kousick Biswas, Jennifer M Gabany, Jacquelyn A Quin, Jerene M Bitondo, Faisal G Bakaeen, Rosemary F Kelly, Laurie A Shroyer, and Deepak L Bhatt. 2014. “Choice of vein-harvest technique for coronary artery bypass grafting: rationale and design of the REGROUP trial.” Clin Cardiol, 37, 6, Pp. 325-30.Abstract
The Randomized Endo-vein Graft Prospective (REGROUP) trial ( NCT01850082) is a randomized, intent-to-treat, 2-arm, parallel-design, multicenter study funded by the Cooperative Studies Program (CSP No. 588) of the US Department of Veterans Affairs. Cardiac surgeons at 16 Veterans Affairs (VA) medical centers with technical expertise in performing both endoscopic vein harvesting (EVH) and open vein harvesting (OVH) were recruited as the REGROUP surgeon participants. Subjects requiring elective or urgent coronary artery bypass grafting using cardiopulmonary bypass with use of ≥1 saphenous vein graft will be screened for enrollment using pre-established inclusion/exclusion criteria. Enrolled subjects (planned N = 1150) will be randomized to 1 of the 2 arms (EVH or OVH) after an experienced vein harvester has been assigned. The primary outcomes measure is the rate of major adverse cardiac events (MACE), including death, myocardial infarction, or revascularization. Subject assessments will be performed at multiple times, including at baseline, intraoperatively, postoperatively, and at discharge (or 30 days after surgery, if still hospitalized). Assessment of leg-wound complications will be completed at 6 weeks after surgery. Telephone follow-ups will occur at 3-month intervals after surgery until the participating sites are decommissioned after the trial's completion (approximately 4.5 years after the full study startup). To assess long-term outcomes, centralized follow-up of MACE for 2 additional years will be centrally performed using VA and non-VA clinical and administrative databases. The primary MACE outcome will be compared between the 2 arms, EVH and OVH, at the end of the trial duration.
Alaa Shalaby, Marwan Refaat, Joan Lacomis, and Marco Zenati. 2014. “Post occlusive left atrial appendage thrombosis with extension into the left atrium.” BMJ Case Rep, 2014.Abstract
A 67-year-old man underwent left atrial appendage (LAA) exclusion concomitant with mitral valve surgery and radiofrequency ablation maze procedure. On transoesophageal echocardiography anticipating ablation for left atrial tachycardia, an echodense thrombus was visualised in the LAA location with apparent intracavitary extension into the left atrium. Based on CT imaging findings, the echo represented thrombosis of a large left atrial appendage with probable extension into the left atrium.
Faisal G Bakaeen, Marco A Zenati, and Deepak L Bhatt. 2013. “Conduits in coronary artery bypass grafting.” Semin Thorac Cardiovasc Surg, 25, 4, Pp. 273-9.Abstract
Modern cardiac practice in the United States is conservative when it comes to using bilateral internal mammary or radial artery grafts in coronary artery bypass surgery. Here, we examine the evidence regarding using other arterial grafts instead of veins as a complement to left internal mammary artery in surgical revascularization. In addition, we put our report in perspective relative to prevailing practice, professional societal guidelines, and future directions in coronary artery bypass grafting.
Benjamin A Steinberg, Philip D Beckley, Thomas F Deering, Carol L Clark, Alpesh N Amin, Kenneth A Bauer, Byron Cryer, Moussa Mansour, James M Scheiman, Marco A Zenati, Kristin L Newby, Frank W Peacock, and Deepak L Bhatt. 2013. “Evaluation and management of the atrial fibrillation patient: a report from the Society of Cardiovascular Patient Care.” Crit Pathw Cardiol, 12, 3, Pp. 107-15.Abstract
Atrial fibrillation (AF) is the most common cardiac dysrhythmia, and its prevalence is growing. The care of patients with AF is complex and involves multiple specialties and venues of care. Guideline recommendations are available for AF therapy; however, their implementation can be challenging. The Society of Cardiovascular Patient Care has developed an accreditation program, formulated by an expert committee on AF. Accreditation is based on specific criteria in 7 domains: (1) community outreach, (2) prehospital care, (3) early stabilization, (4) acute care, (5) transitions of care, (6) clinical quality measures, and (7) governance. This document presents the rationale, discussion, and supporting evidence for these criteria, in an effort to maximize effective and efficient AF care.
Nathan A Wood, Kevin Waugh, Tian Yu Tommy Liu, Marco A Zenati, and Cameron N Riviere. 2013. “Space-Time Localization and Registration on the Beating Heart.” Rep U S, 2012, Pp. 3792-3797.Abstract
This paper presents a framework for localizing a miniature epicardial crawling robot, HeartLander, on the beating heart using only 6-degree-of-freedom position measurements from an electromagnetic position tracker and a dynamic surface model of the heart. Using only this information, motion and observation models of the system are developed such that a particle filter can accurately estimate not only the location of the robot on the surface of the heart, but also the pose of the heart in the world coordinate frame as well as the current physiological phase of the heart. The presented framework is then demonstrated in simulation on a dynamic 3-D model of the human heart and a robot motion model which accurately mimics the behavior of the HeartLander robot.
Nagina Malguria, Michael Hanley, Michael Steigner, Kanako K Kumamaru, Nicole Wake, Marco Zenati, and Frank J Rybicki. 2013. “Static and cine CT imaging to identify and characterize mediastinal adhesions as a potential complication for patients underdoing "redo sternotomy".” AJR Am J Roentgenol, 201, 1, Pp. W72-4.Abstract
OBJECTIVE: The purpose of this article is to describe the image acquisition, identification, and reporting of postoperative adhesions in patients undergoing CT for "redo sternotomy" surgical planning. CONCLUSION: Adhesions appear as linear fibrous bands that join structures in the mediastinum viewed on static images. Confirmation by cine imaging shows deformation of mediastinal structures. Identification and reporting of adhesions will likely guide surgeons to safer interventions.
Hossein G Almassi, Sharon A Pecsi, Joseph F Collins, Laurie A Shroyer, Marco A Zenati, and Frederick L Grover. 2012. “Predictors and impact of postoperative atrial fibrillation on patients' outcomes: a report from the Randomized On Versus Off Bypass trial.” J Thorac Cardiovasc Surg, 143, 1, Pp. 93-102.Abstract
OBJECTIVE: The study objective was to determine the predictors of postoperative atrial fibrillation (POAF) in patients randomized to conventional coronary artery bypass graft (on-pump coronary artery bypass [ONCAB]) versus beating heart coronary surgery (off-pump coronary artery bypass [OPCAB]). METHODS: The subgroup of 2103 patients (of 2203 enrollees) in the Randomized On Versus Off Bypass trial with no POAF was studied (1056 patients in the ONCAB group and 1047 patients in the OPCAB group). Univariate and multivariate analyses were used to identify the predictors of POAF and the impact of POAF on outcomes. RESULTS: Use of ONCAB versus OPCAB was not associated with increased rates of POAF. Older age (P < .0001), white race (P < .001), and hypertension (P < .002) were predictors of POAF on multivariate analysis. In general, POAF led to a higher rates of reintubation (ONCAB: 6.3% vs 0.8% no POAF, P < .001; OPCAB: 7.4% vs 1.8% no POAF, P < .0001) and prolonged ventilatory support (ONCAB: 7.1% vs 2.3% no POAF, P = .001; OPCAB: 9.2% vs 3.4% no POAF, P = .0003). The rate of any early adverse outcome was higher in patients with POAF (all patients: 10% POAF vs 4.7% no POAF, P < .0001; ONCAB: 9% POAF vs 4.3% no POAF, P = .008; OPCAB: 11% POAF vs 5.1% no POAF, P = .001). The 1-year all cause mortality was higher with POAF for both groups (ONCAB: 5.4% POAF vs 2% no POAF, P = .009; OPCAB: 5.1% POAF vs 2.6% no POAF, P = .07). POAF was independently associated with early composite end point (odds ratio [OR], 2.23; confidence interval [CI], 1.55-3.22; P < .0001), need for new mechanical support (OR, 3.25; CI, 1.39-7.61; P = .007), prolonged ventilatory support (OR, 2.93; CI, 1.89-4.55; P < .0001), renal failure (OR, 5.42; CI, 1.94-15.15; P = .001), and mortality at 12 months (OR, 1.94; CI, 1.14-3.28; P = .01). CONCLUSIONS: In the Randomized On Versus Off Bypass trial, the strategy of revascularization did not affect the rate of POAF. Age, race, and hypertension were predictors of POAF. POAF was independently associated with a higher short-term morbidity and higher 1-year mortality rates.
NA Patronik, MA Zenati, and CN Riviere. 2012. “A Study Ex Vivo of the Effect of Epicardial Fat on the HeartLander Robotic Crawler.” IFMBE Proc, 37, Part 1, Part 3, Pp. 227-230.Abstract
A tethered epicardial crawling robot known as HeartLander has been developed for minimally-invasive surgery on the beating heart. The crawler has been tested in vivo many times in a porcine model, a model which provides generally authentic conditions in many ways; however, the pigs tested generally have little epicardial fat, whereas the epicardial fat in human patients will be considerable. As a result, it is necessary to determine the effect of such fat on the performance of the crawler. In one experiment, using fresh ovine hearts ex vivo, clogging of the suction chambers of the crawler during sliding over tissue with active suction was investigated for a variety of thicknesses of epicardial fat. In a second experiment, the maximum traction force during each step was measured when sliding with active suction repeatedly over the same location for a variety of fat thicknesses. The clogging experiment showed accumulation of fat in the suction chamber, with the amount dependent on the state of the epicardial membrane, but the suction line did not clog. The traction experiment showed that traction was maintained in all cases except when the epicardial membrane was excised completely.
Nicholas A Patronik, Takeyoshi Ota, Marco A Zenati, and Cameron N Riviere. 2012. “Synchronization of epicardial crawling robot with heartbeat and respiration for improved safety and efficiency of locomotion.” Int J Med Robot, 8, 1, Pp. 97-106.Abstract
BACKGROUND: HeartLander is a miniature mobile robot designed to navigate over the epicardium of the beating heart for minimally invasive therapy. This paper presents a technique to decrease slippage and improve locomotion efficiency by synchronizing the locomotion with the intrapericardial pressure variations of the respiration and heartbeat cycles. METHODS: Respiratory and heartbeat phases were detected in real time using a chest-mounted accelerometer during locomotion in a porcine model in vivo. Trials were conducted over the lateral aspect of the heart surface to test synchronized locomotion against an unsynchronized control. RESULTS: Offline evaluation showed that the respiration and heartbeat algorithms had accuracies of 100% and 88%, respectively. Synchronized trials exhibited significantly lower friction, higher efficiency, and greater total distance traveled than control trials. CONCLUSION: Synchronization of the locomotion of HeartLander with respiration and heartbeat is feasible and results in safer and more efficient travel on the beating heart.
Nathan A Wood, David Schwartzman, Marco A Zenati, and Cameron N Riviere. 2012. “Toward Onboard Estimation of Physiological Phase for an Epicardial Crawling Robot.” Proc IEEE RAS EMBS Int Conf Biomed Robot Biomechatron, 2012, Pp. 6290716.Abstract
HeartLander is a miniature mobile robot which adheres to and crawls over the surface of the beating heart to provide therapies in a minimally invasive manner. Although HeartLander inherently provides a stable operating platform, the motion of the surface of the heart remains an important factor in the operation of the robot. The quasi-periodic motion of the heart due to physiological cycles, respiration and the heartbeat, affects the ability of the robot to move, as well as localize accurately. In order to improve locomotion efficiency, as well as register different locations on the heart in physiological phase, two methods of identifying physiological phases are presented: sliding-window-based and model-based. In the sliding-window-based approach a vector of previous measurements is compared to previously learned motion templates to determine the current physiological phases, while the model-based approach learns a Fourier series model of the motion, and uses this model to estimate the current physiological phases using an Extended Kalman Filter (EKF). The two methods, while differing in approach, produce similarly accurate results on data recorded from animal experiments in vivo.