Return to work after coronary artery bypass grafting and aortic valve replacement surgery: A scoping review.

BACKGROUND: Coronary artery bypass grafting surgery and aortic valve replacement surgery are essential treatment options for people suffering from angina pectoris or aortic valve disease. Surgery aims to prolong life expectancy, improve quality of life, and facilitate participation in society for the individuals afflicted. The aim of this review was to explore the literature on work participation in patients following coronary artery bypass grafting or aortic valve replacement surgery, and to identify demographic and clinical characteristics associated with returning to work. METHODS: A scoping review framework of Arksey and O'Malley was chosen. Four electronic databases: Medline, CINAHL, Embase, and Google Scholar were searched for studies in English, Swedish, Danish or Norwegian between January 1988 and January 2020. A blinded selection of articles was performed. The data were then charted and summarized by descriptive numerical analyses and categorized into themes. RESULTS: Forty-five out of 432 articles were included in the final full-text analysis. Absence from work following coronary artery bypass graft grafting or aortic valve replacement surgery lasted on average 30 weeks, whereas 34% of the patients never returned to work. Being female, suffering from pre-existing depression, having limited secondary education, or low income were associated with decreased return to work rates. Previous employment was a decisive factor for returning to work after surgery. Data on return to work after aortic valve replacement were scarce. CONCLUSIONS: A significant number of patients never return to work following coronary artery bypass grafting or aortic valve surgery, and the time interval until work return is longer than expected. Failure to resume work represents a threat to the patients' finances and quality of life. Nurses are in a unique position to assess work-related issues and have an active part in the multi-disciplinary facilitation of tailored occupational counselling after cardiac surgery.

Implementation of a beating heart system for training in off-pump and minimally invasive coronary artery bypass.

BACKGROUND: Several training devices have been developed to train anastomotic skills in off-pump coronary artery bypass grafting (OPCAB). However, assessment of trainees' improvement remains challenging. The goal of this study was to develop a new practical scoring chart and investigate its reliability and utility for anastomotic skills in OPCAB and minimally invasive direct coronary artery bypass (MIDCAB). METHODS: A training device was used, which included a beating heart model installed in a dedicated box. A soft plastic tube was used as the left anterior descending artery, and a porcine ureter was used as the left internal mammary artery. Five cardiac surgery fellows (Fellows, > 5 year of surgical experience) and five residents or medical students (Residents, ≤ 5 year of surgical experience) were enrolled for this study. Before and after training, skills were evaluated using a scoring chart that took into account anastomotic time, leakage, shape, flow measurement, and self-estimation. RESULTS: Mean total score of all trainees was 15.4 ± 4.0 at pre-training and 18.5 ± 2.4 at post-training (P = 0.05). Before training, there was a significant difference in the total score between Fellows and Residents (18.6 ± 2.2 vs 12.2 ± 2.4 points, P = 0.002), which disappeared after training (19.4 ± 2.5 vs 17.6 ± 2.2 points, P = 0.262). Residents benefitted from training with improvements in their time, total score, score for time, score for flow and subtraction score; however, these effects were not seen in Fellows. The most evident training effect was improvement of self-estimation, which was also seen in Fellows. CONCLUSIONS: Residents were most likely to derive benefit from these training models with regard to both efficiency and quality. Training models seem to have an important role in making surgeons feel more comfortable with the procedure.

Experience with porcine beating heart simulator for coronary artery bypass surgery residency training.

OBJECTIVE: To evaluate the effect of our uniquely designed beating heart simulator for coronary artery bypass surgery residency training. METHODS: The balloon of intra-aortic balloon pump (IABP) was inserted into the left ventricle of an isolated porcine heart to form a beating heart simulator. This model simulated off-pump coronary artery bypass grafting (OPCABG), and the nonbeating heart model simulated the on-pump coronary artery bypass grafting (ONCABG) for training of surgeons. From 2017 to 2019, 60 trainees were randomly divided into nonbeating and beating heart simulator training groups. The training period was 3 months. The performance of anastomosis was evaluated at the beginning (after 1 month), midpoint (after 2 months), and at the end of the assessment (after 3 months). RESULTS: Trainees improved their performance of coronary artery anastomosis respectively after 3 months of training, whether they were trained on beating heart simulator or nonbeating heart simulator (P < .05). On both nonbeating and beating heart simulator test, trainees in the beating group performed better than those in the nonbeating group in the use of microsurgical instruments, anastomotic quality, and anastomotic speed after 3 months of training (P < .05). CONCLUSIONS: The effect of our uniquely developed beating heart simulator training was better than those of nonbeating heart simulator for OPCABG and ONCABG training of surgeons during residency.

Coronary Anastomosis Simulation: Directed Interventions to Optimize Success.

BACKGROUND: The role of simulation-based training in coronary artery bypass grafting remains undefined. Barriers to simulator use include clinical and personal obligations, insufficient materials, and lack of mentorship. The purpose of this study was to implement a longitudinal, residency-wide coronary anastomosis simulation curriculum. METHODS: A prospective observational study was conducted from 2018 to 2019 at a single academic center. All residents of the Thoracic Surgery training program participated. Each participant was provided a low-fidelity coronary anastomosis simulator, high-quality instruments, and faculty mentor. Formal assessments were held quarterly, and residents were encouraged to practice alone and with their mentor. Baseline and follow-up metrics were compared with simple descriptive statistics. RESULTS: Seventeen residents and 12 faculty participated in the study. Residents demonstrated increased use of the simulator, with 21% participating in independent practice at baseline and 82% in the fourth quarter (P = .02). The median score on the Thoracic Surgery Directors Association Vessel Anastomosis Assessment improved from 42 out of 65 at baseline to 54 out of 65 in the fourth quarter (P = .04), and mean anastomosis time was reduced by 5 minutes 6 seconds (P = .02). Over 12 months, junior residents demonstrated a mean reduction in anastomosis time of 6 minutes 36 seconds, and senior residents decreased anastomosis time by 3 minutes 6 seconds (P = .02). CONCLUSIONS: Providing residents with a low-fidelity coronary anastomosis trainer with high-quality instruments and a faculty mentor improved rates of independent practice, Thoracic Surgery Directors Association assessment scores, and anastomosis time. Our next step is validating the coronary simulator curriculum by measuring improvement of resident performance in the operating room.

Simulation Training in Minimally Invasive Direct Coronary Artery Bypass Grafting.

BACKGROUND: To evaluate the effect of minimally invasive direct coronary artery bypass (MIDCAB) simulator for cardiac residency training. METHODS: A total of 26 resident surgeons who had never trained for coronary artery anastomosis participated in this training program. They received coronary artery anastomosis training on off-pump coronary artery bypass grafting (OPCAB) simulator for 15 h. After training, their performance of anastomosis was evaluated on the OPCAB simulator according to 12 items and a 5-point global rating scale. Based on the total score of assessment, those with an individual score of 12-36 formed group A, while group B was composed of the remaining trainees. The two groups then received another 15 h coronary artery anastomosis training on the MIDCAB simulator, and the performance was assessed. RESULTS: Trainees improved their performance of coronary artery anastomosis after training on the OPCAB simulator. Group A was composed of 7 trainees with an individual with a total score of 12-36 points and group B was composed of the remaining 19 trainees. After MIDCAB simulator training, significant differences were noted in the pre- and post-training values in the A group (P < .001), and the assessment value of group A was significantly better than those of group B (P < .05). No significant difference was detected between pre- and post-training values in group B after MIDCAB simulator training (P > .05). CONCLUSION: We concluded that trainees who performed well in OPCAB simulation training can also perform better in MIDCAB, and our designed MIDCAB simulator was useful for residency training.

Comparison of the effects of coronary artery anastomosis training between senior and junior surgeons.

OBJECTIVE: Many countries are facing a shortage of cardiac surgeons, who are crucial in meeting the demands of growing number of patients in need of coronary artery bypass grafting. This situation poses a serious challenge, especially in China. The purpose of this study is to determine whether cardiac surgeons are suitable for training in coronary artery anastomosis at an earlier stage in their career. METHODS: We divided 12 cardiac surgeons with no prior experience in coronary artery anastomosis into senior and junior groups for training and assessment. All trainees received training in coronary artery anastomosis for a defined period. We performed in vivo and in vitro examinations before and after training, respectively. Additionally, we assessed individual surgical performance of surgeons by using performance rating scores, including different aspects of surgical skills rated on a five-point scale. RESULTS: The post-training scores (overall, junior, senior) were significantly higher than the pre-training scores (overall, junior, and senior). We observed no differences in pre-training and post-training scores between the junior and senior groups. CONCLUSION: Senior surgeons did not had any significant advantages over junior surgeons with respect to coronary artery anastomosis in the absence of training. Junior surgeons achieved the same results as the senior surgeons after training.

Train early and with deliberate practice: simple coronary surgery simulation platform results in fast increase in technical surgical skills in residents and students.

OBJECTIVES: The amount of intense and focused training with the specific goal to improve performance (i.e. deliberate practice) is a predictor of expert-level performance in multiple domains of psychomotor skill learning. Simulation training improves surgical skills in cardiac surgery. We established a training programme that enables early surgical exposure and assessment. We investigated the training effects in coronary surgery simulations in trainees with different levels of surgical experience. METHODS: The early surgical exposure and assessment programme comprises a low- and high-fidelity simulation, self-organized training, instructed workshops and a stepwise challenge increase. Performance was assessed with a multidimensional skill matrix using video recordings. Two groups of trainees [students (N = 7), 1-/2-year residents (N = 6)] completed introductory training (pretraining, level 1) and two 3-week training periods (levels 2 and 3). Fellows (N = 6) served as controls. Residents and students underwent deliberate practice training with specific training targets. Fellows performed regularly scheduled coronary surgery cases. Entry and exit assessments were conducted for levels 2 and 3. RESULTS: Fellows did not improve overall performance. Residents and students showed significant improvements in both technical accuracy and completion times. Residents reached an overall performance level comparable to fellows. Students reached similar accuracy of surgical skills with longer completion times [level 3 exit score/time: fellows 27 (24-29)/min; residents 27 (21-30)/min, P = 0.94; students 17 (17-25)/min, P = 0.068]. CONCLUSIONS: Deliberate practice training resulted in a fast and substantial increase in surgical skills in residents and students. Unexperienced residents reach performance levels of fellows. Deliberate practice simulation programmes should be a mandatory component of surgical training.

The implication of seniority of supervising attending surgeon on the reexploration rate following elective coronary artery bypass grafting.

BACKGROUND AND AIMS: During coronary artery bypass graft (CABG) surgery, the residual hemostasis procedures, from weaning cardiopulmonary bypass to closing sternotomy, are always completed by residents and supervised by attending surgeons. We want to evaluate the teaching effectiveness for residents under the supervision of attending surgeons with different levels of seniority. MATERIALS AND METHODS: Between January 1st 2001 and December 31st 2010, 2279 consecutive CABG surgeries were performed in our medical center. In total, 83 patients underwent a reexploration for postoperative bleeding. All causes of bleeding were identified and recorded. Competent attending surgeons were defined as having >3 years' experience and young attending surgeons with ≦3 years' experience. We compared the reexploration rate and aimed to identify the common sources of bleeding by the two groups. We also assessed the impact of attending experience on the outcomes and major complications after reexploration. RESULTS: There were 36 surgical bleeding and 17 non-surgical bleeding in the young group and 16 surgical bleeding and 14 non-surgical bleeding in the competent group. The young group experienced more mediastinal drainage before a reexploration and a longer time interval to a reexploration. However, both are without statistical significance. Furthermore, the young group has a significant longer hospital stay. The most common intra-pericardium surgical bleeding included two-stage cannulation, side branch of the left internal mammary artery (LIMA), and side branch of vein grafts. The most common extra-pericardium surgical bleeding included a puncture hole by sternal wires, LIMA bed, and fragile sternum. CONCLUSION: Young attending surgeons indeed had both higher incidence of reexploration and surgical bleeding after a CABG. However, the supervisor experience only impacted hospital stay, not major complications or mortality after a reexploration. This might imply the competent attending surgeons provide higher teaching effectiveness for the hemostasis procedure after CABG.

3D printing for preoperative planning and surgical training: a review.

Surgeons typically rely on their past training and experiences as well as visual aids from medical imaging techniques such as magnetic resonance imaging (MRI) or computed tomography (CT) for the planning of surgical processes. Often, due to the anatomical complexity of the surgery site, two dimensional or virtual images are not sufficient to successfully convey the structural details. For such scenarios, a 3D printed model of the patient's anatomy enables personalized preoperative planning. This paper reviews critical aspects of 3D printing for preoperative planning and surgical training, starting with an overview of the process-flow and 3D printing techniques, followed by their applications spanning across multiple organ systems in the human body. State of the art in these technologies are described along with a discussion of current limitations and future opportunities.

Bilateral Internal Mammary Artery Use Can Be Safely Taught Without Increasing Morbidity or Mortality.

BACKGROUND: Evidence shows a likely survival benefit with the use of bilateral internal mammary arteries (BIMA) compared with a single internal mammary artery (SIMA). Nonetheless, BIMA use is often not used or taught because of a perceived increase in operative time and complexity. This study aimed to evaluate operative time, morbidity, and mortality in both resident and nonresident cases using BIMA compared with SIMA. METHODS: Consecutive patients undergoing isolated coronary artery bypass grafting (October 2012 to April 2015) at a single institution were reviewed. Cases were stratified on the basis of the use of SIMA versus BIMA and resident teaching versus nonresident teaching cases. Primary outcomes included operative time, postoperative morbidity, and mortality. RESULTS: A total of 416 patients were identified; 335 of 416 (81%) patients received a SIMA, and 81 of 416 (19%) patients received BIMA. A total of 184 of 416 (44%) were resident cases: 143 of the 335 (43%) SIMA cases and 41 of the 81 (51%) BIMA cases. Use of BIMA in resident cases was associated with a longer operative and cardiopulmonary bypass (CPB) time than resident SIMA cases, but this increased time did not affect morbidity or mortality. Use of SIMA versus BIMA in nonresident cases had no significant difference on total operative time, CPB time, postoperative morbidity, or mortality. Overall, operative and 1-year mortality rates were similar in the SIMA and BIMA groups (SIMA: 1.2%, 1.8%, respectively; BIMA: 0%, 0%, respectively; p = NS). CONCLUSIONS: In the hands of an experienced surgeon, BIMA use can be effectively performed without an increase in operative or CPB time. In resident teaching cases, BIMA use may increase operative time, but it can be safely taught without affecting morbidity or mortality.

Novel Dry-Lab Training Method for Totally Endoscopic Coronary Anastomosis: A Pilot Study.

OBJECTIVE: We describe our original dry-lab training system for nonrobotic and beating heart endoscopic coronary artery anastomosis. METHODS: All the materials used for this training were commercially available. We selected a boxed machine, which can produce pulsatile movements of artificial vessels, and on its roof, we installed a two-dimensional home video camera and a monitor. A multiple-holed plate was placed in front of the machine, and through these holes, a trainee inserted endoscopic surgical instruments and anastomosed the artificial vessels by running fashion while watching the monitor. This training program has four stages. During the first stage, a trainee has to demonstrate mastery in conducting a conventional off-pump coronary artery anastomosis without assistance. The second stage is the "nonbeating" version, and the third stage is the "beating" version with the model mentioned previously. After a trainee gets accustomed to the third stage, the original artificial vessel is replaced with an extremely fragile one, and this is the fourth stage. Our trainee conducted one hundred fourth-stage anastomoses and each procedure was recorded with the video camera. We analyzed several factors from the videos and evaluated the efficacy of the training method. We compared the outcomes of the first 50 consecutive anastomoses with the following 50 ones and described the learning curves. RESULTS: The comparison showed a significant decrease in anastomotic time and vessel injury. We considered the quality of anastomosis acceptable after 47 anastomoses, and anastomotic time fell below 15 minutes at the 81st training at the fourth stage. CONCLUSIONS: Our dry-lab system might be an effective training method for endoscopic coronary anastomosis.

Consensus-Derived Coronary Anastomotic Checklist Reveals Significant Variability Among Experts.

BACKGROUND: Surgical skill assessment tools frequently reflect the opinions of small groups of surgeons. That raises concerns over their generalizability as well as their utilization when applied broadly. A Delphi approach could engage a broad group of experts to identify key elements for a checklist assessing coronary anastomotic skill, improving generalizability. METHODS: Expert surgeons in North America (10 or more years in practice, actively teaching coronary artery surgery) were contacted randomly to participate. Consenting surgeons first provided items they believed were mandatory when performing a coronary artery bypass. These were then entered into a three-round Delphi. Positive consensus was reached when 75% or more of participants ranked an item mandatory. RESULTS: Sixteen faculty consented to participate. Each participant provided 25 ± 10 items. The 407 items provided were condensed, resulting in 146 items in the final list, divided into six sections based on the conduct of the operation. Twenty-three items reached consensus in the first round, 14 in the second, and 3 in the third. These 40 items represented only 27% of the initial 146 items. Agreement within sections varied widely, from 0% for "management of assistants" to 47% for "testing and final steps." CONCLUSIONS: A randomly selected group of experts using a Delphi approach can generate a checklist to assess construction of a coronary artery bypass. Considerable disagreement among experts regarding what steps are mandatory calls into question the generalizability of any locally developed checklist.

Training in Coronary Artery Bypass Surgery: Tips and Tricks of the Trade.

Coronary artery bypass is often the first procedure cardiac surgeons are confronted with during their residencies. This article discusses the surgical steps and the potential difficulties encountered during this procedure and how they can be solved. The "point of view" of an experienced surgeon is provided to the trainees and to the readers.

How Safe Is it to Train Residents to Perform Coronary Surgery With Multiple Arterial Grafting? Nineteen Years of Training at a Single Institution.

The learning curve of coronary artery bypass grafting (CABG) with multiple arterial grafting (MAG) is perceived to be associated with increased surgical morbidity and potentially poorer long-term outcomes. We compared short-term outcomes and long-term survival in patients who underwent CABG with MAG performed by attending surgeons or resident trainees at a single institution over a period of 19 years. Using our institutional database, we identified 3039 patients undergoing MAG from 1996-2015. Of those, 958 (32%) were operated on by residents and 2081 (68%) by attending surgeons. Propensity score matching and mixed-effects models were used to compare the 2 groups. Operative mortality rate was 0.3% and 0.4% among patients operated by residents and attending surgeons, respectively (P = 0.71), with no significant differences among the groups in postoperative complications. After a mean follow-up time of 11 ± 4 years, survival probability at 5, 10, and 15 years was 95.1% ± 0.7% vs 96.4% ± 0.6%, 87.0% ± 1.1% vs 87.8% ± 1.1%, and 76.6.% ± 1.8% vs 77.6% ± 1.8% in the resident and attending surgeon group, respectively. Resident and attending surgeon cases showed comparable risk of death (hazard ratio [HR] = 1.01; 95% CI: 0.80-1.28; P = 0.92). The equipoise between the 2 groups was confirmed among cases receiving bilateral internal thoracic arteries only (HR = 0.88; 95% CI: 0.54-1.43; P = 0.61), radial artery (HR = 1.22; 95% CI: 0.92-1.61; P = 0.15), or their combination (HR = 0.74; 95% CI: 0.33-1.65; P = 0.47). The present analysis confirms that adequately supervised trainees can perform CABG with MAG without compromising patient safety and long-term survival.

Outcomes of Trainees Performing Coronary Artery Bypass Grafting: Does Resident Experience Matter?

BACKGROUND: Outcomes after coronary artery bypass graft surgery (CABG) are known to be dependent on attending surgeon volume, but the impact of resident experience is unknown. Our objective was to assess the influence of resident experience to understand the learning curve for CABG. METHODS: From 2008 to 2014, all isolated on-pump CABG (n = 1,668) during which a resident performed the entire operation (including sternotomy, mammary artery harvest, coronary anastomoses, and closure) were reviewed. Operations were stratified by individual resident CABG experience. Primary outcomes included operative time, which was further divided into "opening time" (incision to bypass initiation), cardiopulmonary bypass times, cross-clamp times, and "closing times" (bypass termination to close). Secondary outcomes included 30-day mortality and major complications. RESULTS: Operative time was 29.7 minutes longer (p < 0.001) during residents' first 30 CABG, primarily driven by longer opening and closing times. After controlling for resident, attending physician, preoperative risk, number of grafts, and redo status, the completion of 30 operations improved operative time by 25 minutes (p < 0.001), the majority of which included opening time (13 minutes, p < 0.001). Minor differences in bypass and cross-clamp times were not clinically meaningful, and there were no differences in 30-day mortality or major complications with respect to resident experience. CONCLUSIONS: Total operative time during CABG is dependent on resident experience, with significant improvement by approximately the 30th case. Importantly, these differences do not translate into worse outcomes. These data support trainees performing all components of CABG-even early in the residency experience.

Simulation of Anastomosis in Coronary Artery Bypass Surgery.

Developing cardiac surgical skills and experience takes years of practice. Cardiac trainees need to develop technical proficiency in order to enhance quality of care and patient safety. Simulation-based models are common resources for teaching procedural skills in both undergraduate and postgraduate medical education. Suitable and accessible educational platforms can play a progressively important role in the training process for young surgeons in the area of cardiac surgery. Coronary artery bypass graft (CABG) surgery consists of a wide range of pathologic anatomies and surgical techniques. In this paper we introduce a novel, synthetic, biomimetic platform that allows for the realistic practice of the CABG surgery. The prototype uses a polyvinyl alcohol hydrogel which has been designed to mimic the geometric properties of vasculature. The proposed models look and feel like human tissue and possess somewhat consistent mechanical properties. In this study, we apply the platform to simulate a case of autogenous saphenous vein bypass grafting of a patient. An autogenous saphenous vein graft is placed from the aorta to the left anterior descending coronary artery. The standard procedures of the coronary artery bypass surgery were successfully simulated. Using the proposed technology, other complicated surgeries such as end to end, side to end, and sequential anastomoses can be simulated such that these models lend themselves very well to various types of anastomoses.

Single crossclamp: Safe training tool for coronary artery bypass grafting.

OBJECTIVE: The single-crossclamp technique for coronary artery bypass grafting is recognized to reduce manipulation of the ascending aorta, and thereby improve neurological outcomes. However, there is a perceived disadvantage of long cardiopulmonary bypass and crossclamp times. Our objective was to evaluate outcomes with this technique and determine whether it is safe for training. METHODS: Patients undergoing coronary artery bypass between October 2005 and February 2014 with use of the single-crossclamp method were divided into 2 groups: a consultant group (n = 1024), and a trainee group (n = 504), depending on the primary surgeon. Their outcomes were compared. RESULTS: The consultants operated on more nonelective patients who had a higher risk profile (mean additive EuroSCORE I 4.05 vs. 3.80, p = 0.085; logistic EuroSCORE I 4.36 vs. 3.64, p = 0.002). There were 9 (0.9%) deaths in the consultant group and 5 (1%) in the trainee group. The mean number of grafts in the consultant group was greater, but the crossclamp time was similar and cardiopulmonary bypass time was shorter. There were 4 (0.4%) cerebrovascular events in the consultant group and 3 (0.6%) in the trainee group. Postoperative stay was shorter in the trainee group (7.19 vs. 7.97 days, p = 0.033). Other complication rates were similar. CONCLUSIONS: The technique has excellent outcomes, especially neurological, and is safe for training junior surgeons.

Characterizing the Operative Experience of Cardiac Surgical Trainees: What Are Residents Really Doing in the Operating Room?

BACKGROUND: The present study aimed to describe and compare the operative experience of cardiothoracic surgical residents for basic and advanced cardiac surgical procedures. METHODS: Data were obtained from the 2015 Thoracic Surgery Directors Association Survey administered to all thoracic surgical residents taking the yearly In-Service Training Examination (n = 356). Residents were asked whether they routinely served as the operative surgeon on various cardiac operations and operative tasks. Results were stratified by postgraduate year (PGY), residency type, and primary career interest. RESULTS: The survey response rate was 100%. Considering all training pathways, only 2 of 13 cardiac operations surveyed were routinely performed by graduating chief residents as the operative surgeon: coronary artery bypass grafting (CABG; 92%) and aortic valve replacement (AVR; 88%). Off-pump CABG, minimally invasive mitral valve operation, and transcatheter aortic interventions were infrequently (<30% of the time) performed by graduating residents as the operative surgeon. These results were similar when residents with a career interest in general thoracic surgery were excluded from the analysis. For the operative progression of integrated 6-year (I-6) residents, most began to routinely cannulate for cardiopulmonary bypass, perform proximal coronary anastomoses, and harvest the mammary artery during PGY3. The majority (>50%) of I-6 residents performed CABG as the operative surgeon by PGY4. CONCLUSIONS: There is pronounced heterogeneity in the cardiac operative experience of cardiothoracic surgical residents in the United States, with only CABG and AVR routinely performed by graduating residents as the operative surgeon. This heterogeneity may lead to insufficient training in certain procedures for many graduates.