Pictures of the Future    Spring 2006

Why Simulation Saves Lives

A Siemens training center that specializes in simulating complex interventional procedures on the heart helps prospective as well as experienced cardiologists hone their skills.

When pilots climb into the cockpit of an airplane for their very first flight, their every move is sure to be perfectly executed, because flight simulators have prepared them thoroughly for taking on this demanding responsibility. "Regular simulator training has been an integral part of pilots’ training and careers for years," says Professor Wolfram Voelker, Medical Director at the University Medical Clinic in Würzburg. "That’s how they learn to master emergency situations and other challenges."

Now, medical doctors are also venturing into the world of simulators, not to keep planes in the sky, but to keep patients out of trouble. In an effort to avoid beginners’ mistakes or to familiarized themselves with new, advanced surgical techniques, some doctors are turning to simulations that can be practiced without human patients. But in spite of its practical benefits, medical simulation training is still rare. "There are only a handful of training facilities in Europe that offer simulation technology," Voelker explains.

One such facility is the Siemens Medical Solutions Training Center in Forchheim, Germany. Siemens has been conducting workshops for prospective cardiologists at the facility since the fall of 2004.

"The workshops are specifically designed for physicians who want to gain more expertise in surgical heart procedures," explains Voelker, who developed the course concept in cooperation with his colleagues and Siemens. "One of the things doctors practice at the facility is to insert a stent—a small tube of metal mesh—into a constricted coronary blood vessel," he adds. The curriculum of the two-day training course contains practical exercises and seminars.

In addition to simulation facilities such as the Cathi simulator, the Training Center provides a functional heart catheterization laboratory including an X-ray system—i.e. an operating room especially equipped for heart examinations and surgical procedures. Here, doctors undergo training utilizing genuine X-rays, the only difference being that instead of a human patient lying on the operating table, there’s a silicone heart that rhythmically pumps water instead of blood through narrow silicone veins, which permit authentic catheters, wires, balloons and stents to be passed through them. But before they practice here, course participants gain experience at the Cathi simulator.

Dr. Lotte Possler from the Julius Hospital in Würzburg is under pressure there right now. Her "patient"—a full-sized medical dummy—has suffered a heart attack. But which coronary vessel is blocked and where? The affected vessel must be widened quickly to save the patient’s life. Under Voelker’s tutelage, Possler selects the best guide catheter and guide wire. Then she tries to push the thin wire through the coronary artery to the point of constriction. The pushing-forward maneuver is in fact genuine, but the position and the movement of the wire in the blood vessels are calculated by a simulation program and displayed on a monitor. Possler even feels the actual rubbing of the wire against the blood vessel walls, and the movement of the patient’s heart.

Navigating the catheter is by no means easy. The wire curvature isn’t quite right, so Possler has to withdraw it and start over again. She uses virtual X-rays to illuminate the dummy’s heart in order to follow the path through the vessels on the screen. Which setting is the best, and which radiation angle is the most appropriate? As in reality, the aspiring cardiologist has to position the X-ray equipment in the simulation with great skill, so that she can see a good X-ray projection on the screen.

An assisting course participant injects a contrast medium into the dummy’s synthetic artery at Possler’s instruction. Immediately, the monitor shows X-ray images of the vascular system. But no one has to be concerned about excessive radiation exposure for the patient or the team of doctors, or about an overly high dose of contrast agent. Although the X-ray system is genuine and is really put into position, the X-rays themselves are simulated by the Cathi system and the contrast agent is only water.

Now that the wire has passed the point of constriction, Possler’s next task is to push a balloon catheter over the wire in such a way that the tiny balloon is placed at the catheter’s tip in the constricted area. An assistant pumps up the balloon and releases the pressure again after 30 seconds. Following the widening of the vascular wall, Possler has to select and insert the appropriate stent that will stabilize the widened point of constriction permanently. But which is the right one? Should it be 25 mm long? Or would a 30-mm stent with a 3.55-mm diameter be better? Luckily, Possler has an expert standing at her side to offer advice. The stent is inserted and the procedure is successful. The virtual patient has been saved.

Database Heart. "With Cathi, experienced as well as junior cardiologists can perfect their catheter procedures on coronary vessels," explains Ulrike Kornmesser, a physics Ph.D who is the General Manager of Cathi GmbH, a cooperation partner of Siemens Medical Solutions. "They learn how to use instruments and X-ray machines correctly and efficiently, and they gain experience in optimal dosing of contrast agents and X-rays." The models of beating hearts are realistic and the database that supports the heart model on which simulations are based is constantly expanded.

The vascular constrictions integrated into the simulation program can be adapted to varying levels of training. The more the cardiologist practices, the more complex the vascular constrictions become. "We can also simulate complications, such as a contrast agent allergy, dissections—when an artery’s tissue layers split—or perforations of the vascular wall," says Kornmesser. "Doctors can then practice how to handle these situations, which rarely occur in reality." But Kornmesser doesn’t want to reveal how Cathi determines the actual position of the wire in the model and appears to display the heart environment on the monitor as an X-ray image: "That’s a company secret," she says.

Stress-Free Practice. "As a university professor and member of the Interventional Cardiology Work Group of the German Cardiac Society, I have a special interest in optimizing education for our physicians," says Voelker. "The Siemens Training Center is ideal in this regard. State-of-the-art X-ray systems, a very good infrastructure and outstanding support from the Siemens team all play a role. What’s more, the ambience provides a pleasant learning environment that more traditional university clinics don’t always offer."

In conventional hospital training programs, aspiring cardiologists learn new operating techniques by watching and copying. But often the lessons take place on the fly, because the daily hospital routine is hectic and the heart catheter laboratory has to handle a tremendous workload each day. "At the center in Forchheim, on the other hand, workshop participants can take their time working with the different functions of the X-ray system and handling the catheter materials," states Voelker.

The learning concept is bearing fruit. Following two days of intensive training, course participants are highly satisfied with what they’ve learned. "I enjoyed the workshop very much, especially the combination of theory and practical exercises on the model," says Possler. "Before this I had carried out about 300 catheter examinations in the clinic, whereby the emphasis was on making a diagnosis. I’ve performed only a few interventions, such as widening a blood vessel, and never completely on my own. But here, I was able to calmly watch how my colleagues carry out a surgical procedure, and I received individualized instruction from experienced professors as to how to perform it myself—something that just isn’t possible in a busy hospital environment."

"In the future, simulators will mean that physicians will be able to go into their first catheter examination with a certain amount of experience—and without having to gain it on the patient first," predicts Voelker. "And a simulator certificate for certain surgical procedures could become a standard requirement in as little as five years," he adds. The cooperation between Siemens and medical partners results in a high level of training—and ultimately, patients will benefit most of all.
                                                                                                       Ulrike Zechbauer