Fuad Moussa, MD, MSc, MMEd, FRCSC, FACS, FCCP discusses how he designed a curriculum to teach off-pump coronary bypass surgery to new surgeons.
Patients who need coronary artery bypass are getting older and more frail, and the procedures they require are complex. Off-pump coronary artery bypass – performed while the heart is beating – is a viable alternative but it is extremely technically demanding. The author discusses how he designed a curriculum to teach this highly technical skill to new surgeons using simulation.
When a narrowing or blockage in the arteries that supply blood to the heart causes a heart attack, a cardiac surgeon builds a graft to go around the blockage and open the blood flow. Typically, patients are connected to a heart-lung machine, which provides those functions during the procedure. The heart is stopped, and the surgeon works to build the grafts.
During off-pump coronary bypass – or beating-heart surgery – the surgeon builds these grafts while the heart continues to beat on its own.
Off-pump coronary bypass has traditionally been taught using the apprenticeship model -- but there are challenges.
This procedure is performed by just 13 per cent of cardiac surgeons in Canada1 At the University of Toronto, only two surgeons perform this procedure with any relative consistency.
The University of Toronto Cardiac Residency Program is a six-year direct-entry training program that provides wide exposure to adult and congenital abnormalities. Residents are trained using the apprenticeship model complemented by wet lab sessions and weekly didactic sessions. For off pump coronary artery bypass, there have been twice yearly wet lab sessions using anesthetized pigs, but without specific assessment tools.
A survey of cardiothoracic residencies across the United States in 2000 revealed that only 22 per cent of residents had performed more than 20 off-pump coronary bypass procedures during their training, and only 4 per cent of these had performed a complete operation including the most difficult bypass grafts of the circumflex coronary artery2. This may not be enough exposure to produce technical proficiency.
In addition to these concerns, other stresses on the apprenticeship model such as reduced work hours and ethical concerns about practicing on patients have created a need to develop a new way of teaching these highly technical skills.
What has been missing is a structured program that integrates simulation, didactic teaching, progressive skills acquisition and specific assessment tools.
As a cardiac surgeon, surgeon-teacher, and fellow of the Wilson Centre for Research in Education with an interest in simulation, the author set out to develop a progressive simulation-based training program for off-pump coronary artery bypass. The program is grounded in educational theory, and provides a safe opportunity for deliberate practice of the technical skills required to perform the procedure.
To learn all the steps of this surgery at once is overwhelming for residents. We set out to break the procedure down into reproducible tasks.
Working in collaboration with engineers from Colombia, South America, and an educational scientist at the Wilson Centre for Research in Education, the author mapped out the operation. The team observed and recorded 10 off-pump coronary bypass surgeries, with “think aloud” audio recordings of the critical issues that were perceived during the procedures, in order to capture and identify the points where surgical flow deviations are likely to occur during a standard procedure.
Using the diagrammatic language of the Motor and Cognitive Modeling Diagram 3, baseline performance for the first five procedures was mapped into a task-flow diagram, and refined during the remaining five procedures.
Analyzing the diagram allowed us to break the procedure down into small reproducible components that lend themselves well to the creation of simulation modules.
Using the Challenge Point Framework 4 we created five simulation stations and arranged them in increasing order of difficulty. Experience gained at each simulation station is built upon in the next. Each station has an objective and assessment criteria.
We worked with engineering students at the Universitad Pontificia Bolivariana in Colombia, South America, to build the simulation stations and beating heart simulator.
Station 1: Knot Tying.
Knot tying represents the most basic task during the off-pump coronary artery bypass procedure, and so it was the first station. A SmartSIM bench-top simulator was developed by the engineering students that measure air pressure in rubber tubing while the trainees ties surgical knots.
Objective: complete three throws of a one-handed slip knot.
Assessment: appropriate tension, knot security, efficiency of motion.
Station 2: Vascular Anastomosis (Suturing the bypass).
Creation of a vascular anastomosis is common to all parts of this operation. This is when the surgeon sutures the blood vessels together in an end-to-side fashion. A bench top simulator was developed for simulating this suturing technique. Rubber tubing is used to replicate conduits and targets.
Objective: perform the suturing steps for a standard vascular anastomosis.
Assessment: symmetry, efficiency of motion.
Station 3: Anastomosis on the stopped heart.
The engineering students built a silicone replica of the heart. It allows a simulated left internal mammary artery (LIMA) and left anterior descending artery (LAD) end to side anastomosis. This bypass is the most common and most important bypass.
Objective: perform a complete anastomosis on the static heart between the LIMA and the LAD.
Assessment: arteriotomy: in the centre and straight, bevels graft, lie of anastomosis: parallel to LAD, symmetry, efficiency of motion.
Station 4: Anastomosis on the beating heart.
The bench top heart simulator has a pneumatic mechanism that is able to duplicate the beating properties and rhythms of the human heart.
Objective: perform a complete anastomosis on the beating heart between the internal mammary artery (LIMA) and the left anterior descending artery (LAD)
Assessment: asks for help, application of octopus stablilizer, arteriotomy, bevels graft, lie of anastomosis parallel to LAD, symmetry, efficiency of motion.
Station 5: Anastomosis on the enucleated beating heart.
The most technically challenging anastomosis is between a conduit and the obtuse marginal branches of the circumflex coronary artery. To do this, the surgeon is required to move the heart out of the chest cavity (enucleate) to access the underside.
Objective: perform enucleation, perform a complete anastomosis on the beating heart between saphenous vein graft and the obtuse marginal artery.
Assessment: proper positioning, enucleation of heart, application of octopus stabilizer, arteriotomy, lie of anastomosis parallel to obtuse marginal artery, symmetry, efficiency of motion.
Determining and designing the simulation stations for off-pump coronary artery bypass wasn’t enough: these steps are of value when put into a total education curriculum. And so, we developed the simulation-augmented curriculum into a four-phase workshop that takes place over three days.
Phase 1: Didactic session. A powerpoint session with intraoperative video was showed to capture the residents’ attention. Objectives of the workshop set out, and the off-pump procedure and technical skills required explained to the participants. The simulation modules were presented with instructions on proper technique and a video with the surgeon performing the tasks on the simulators.
Phase 2: Pre-test. Participants performed the tasks at each station – in order of increasing complexity – to establish a baseline. Tutors/assessor were briefed on how to conduct global rating.
Phase 3: Deliberate practice with immediate feedback. Participants practiced as long as they wanted at each station. They received feedback back on the spot from the course tutors and other participants.
Phase 4: Post-test. The participants performed all the tasks again, and post-practice performance was determined.
We conducted the workshop with five surgical residents from the University of Toronto. We used a hybrid model to evaluate the program, encompassing traditional outcome-based evaluations as well as process-based evaluations. We also used qualitative methods to further identify areas for improvement.
Overall, we found that using this framework was effective and well received by the participants.
Participants thought that the latter simulation stations were more authentic but recognized the earlier stations were equally important.
Two participants stated that all of the simulation felt authentic: “All of them were equally essential. Probably the off-pump components were most authentic. All of them were realistic.” (Participant 2). “The sutures and instruments were authentic. The conduits were reasonable. The heart model was more realistic.” (Participant 3)
The participants agreed that having a tutor standing with them during the simulated procedure was helpful. Three said it would be beneficial to have more tutors present. One participants said the setting (an office space) was not authentic, and suggested being gloved and gowned in an OR with the supervisor present would be more realistic.
The trainees appreciated the technical skills being presented in a progressive way: “I think the process of the graduated skills was very good.” (Participant 4). All five said the sequencing of the tasks worked well.
Also of value was the repetition of task in a stress-free environment, the participants agreed. “There was exposure to new things in a non-threatening environment – an easy way to develop new skills and knowledge.” (Participant 5).
“It was very different from doing a technique for the first time in the operating room. It was more relaxing in the simulation. It was much safe than doing it on a real patient. For time issues, during the simulation you can take your time during the simulated procedure or skill. It was a much more comfortable than doing it for the first time in the OR.” (Participant 2).
Conclusion and Next Steps
We developed and implemented a progressive simulation-based training program for off-pump coronary artery bypass that is rooted in educational theory, and that provides a safe opportunity for deliberate practice of the technical skills required to perform the procedure.
The residents who participated, though few, rated the experience highly and demonstrated improvement in efficiency and skill development.
Simulation stations for teaching technical skills can’t stand alone: using simulation in conjunction with didactic teaching and organized into a structured workshop, is beneficial for teaching off-pump coronary artery bypass.
A larger, multi-site study is necessary to achieve statistical power.
I have since received a grant through the Sunnybrook Education Research Committee to study this simulation-augmented training program further, with the hope it will be added to the cardiac surgery curriculum at The University of Toronto in the near future.
About the Author
Dr. Fuad Moussa, is a cardiac surgeon at Sunnybrook Health Sciences Centre, Director of Undergraduate Surgical Education, and Assistant Professor in the Department of Surgery at the University of Toronto and recently completed a master’s degree in medical education. He is a member of The Wilson Centre for Research in Education with a special project in simulation in cardiac surgery.
His special interest is in "off-pump" (beating heart) coronary artery bypass surgery and minimally invasive beating heart coronary bypass surgery and he performed Toronto's first double bypass surgery through a small (5 cm) incision under the left breast.
Special acknowledgements are given to the guidance and mentorship of Drs. Adam Dubrowski and Rola Ajjawi. Dr. Sayra Crisancho and The Faculty of Engineering at The Pontificia University in Buccaramanga, Colombia were instrumental in facilitating the design of the simulators and the simulation-augmented curriculum. David Rojas Gualdron provided technical support during the management of the workshop. My clinical partners have shown support and patience for this endeavor.
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