PERSPECTIVE

ROBOTICS IN CARDIAC SURGERY: A DREAM BECOMING REALITY

Gennaro Ismeno, MD; Lucia Torracca, MD; Andrea Quarti, MD; Ottavio Alfieri, MD Division of Cardiac Surgery, San Raffaele Hospital, Milan - ITALY

 ABSTRACT

 Introduction

 THE ROBOT

 THE “DA VINCI” INTUITIVE SURGICAL SYSTEM

 CLINICAL APPLICATIONS

 THE SAN RAFFAELE HOSPITAL EXPERIENCE

 DISCUSSION

 CONCLUSION

 References

ABSTRACT

The introduction of robotic systems in clinical cardiac surgery has offered the possibility to realize complete endoscopic cardiac operations.
These computer-enhanced systems have been applied in coronary surgery, mitral valve surgery and in few simple congenital cardiac defects.
Despite the good clinical results, operative times are still prolonged compared with standard surgery and a number of conversion has been reported.
The early experience with robotic systems has been exciting although his application its limited to selected patients.
Further development in these technologies could extend the application of these techniques to a larger group of patients.
(Heart Views. 2001; 2(3):93-97)
©2001 Hamad Medical Corporation.

Key Words:

     robotic heart surgery    computer-enhanced surgery    endoccopic cardiac surgery

Introduction

The introduction of new surgical instruments, peripheral techniques for cardiopulmonary by-pass and three-dimensional video assistance during the last few years made possible the widespread acceptance of minimally invasive cardiac surgery (1,2).
For many years, median sternotomy was the approach of choice for traditional cardiac surgery.
With the remarkable improvement of clinical results, surgeons thought there was a need to get better operative results with less postoperative trauma.
The technique of minimally invasive surgery was therefore developed.
The main goal of minimally invasive cardiac surgery is to avoid large incisions in order to reduce the overall surgical trauma and to improve aesthetic results(3).
Moreover the technique produces less discomfort and pain.
In addition, patients can be discharged earlier, recover faster and resume normal life.
Consequently, overall surgical costs to the patients are reduced (4,5). Ideally, complete preservation of the integrity of the chest as obtained with totally endoscopic surgical procedures should be the ultimate target of the surgeon.
Although true endoscopic access to the heart may be beneficial to the patient, it has not been realistically feasible due to the constraints of conventional and currently available surgical instruments.
However, with the introduction of computer-enhanced instrumentation systems and robots, the development of totally endoscopic cardiac surgery is becoming a reality.

THE ROBOT

For many years, industry has utilized robots in assembly lines to perform repetitive tasks with high precision at a high frequency.
Similar robots, programmed to carry out a precise task such as drilling a hole or inserting probes, are used in orthopedic surgery and in neurosurgery (6,7).
Robots were introduced into clinical cardiac surgery only in 1998.
The first robot utilized during a cardiac operation was AESOP (Computer Motion, Goleta, CA, USA), which allowed precise positioning of the endoscope during minimally invasive mitral valve solo surgery by simple speech commands (8,9).
The system eliminates the need for an assistant who has to guide the endoscope for the leading surgeon. For endoscopic cardiac surgical applications, two telemanipulation systems are currently in use: the “da Vinci” system (Intuitive Surgical, Mountain
View, CA, USA) and the Zeus telemanipulator made by Computer Motion.

View, CA, USA) and the Zeus telemanipulator made by Computer Motion.
These devices are in constant control by the surgeon who works at an input device called the "master".
A manipulator, termed "slave", executes the commands or motions of the surgeon.
After successful studies in cadavers and animals, both devices are currently undergoing clinical testing and are utilized for a variety of procedures in several institutions throughout the world. Our experience at the S.
Raffaele Hospital is limited to the “da Vinci” system.

THE “DA VINCI” INTUITIVE SURGICAL SYSTEM

This system (Fig 1) has two primary components: the surgeon’s viewing and control console, the "master" and surgical arm unit.
The surgical arm unit has three arms: two arms hold two instruments and the third arm holds the camera.
These arms are introduced into the body through ports.
The arms' placement into the body is regulated by a system that assures that at the point of contact between the body and the arms, only rotation movements are allowed and not translations to eliminate the risk that the forces applied to the system are transmitted to the patient.
Through these arms, different types of instruments are inserted into the surgical field.
The tips of the instruments are designed like standard surgical instruments with functions such as needle holder, scissors, dissectors and scalpel.
All the instruments have a tiny electro-mechanically controlled wrist (Endo-WristTM) that offers seven degree of freedom to the tip of the instruments, and thus providing the dexterity and flexibility of the human hand.
Instrument tips in the display are electronically aligned to ensure the hand-eye orientation and natural feeling found in conventional surgery.
The third arm holds the camera. This is a 3-dimensional endoscope with two separate optical channels.
Two 3-chip CCD cameras with 800 lines of resolution are used.
The images are presented directly in the viewer on the two continuous tone CRT monitors.
Resolution of the scope is 2.0 mrad/line pair. Working with the system, the surgeon sits at the console and looks at the operative field through the monitor.
Beneath the monitor he grasps two handles that can be rotated, advanced, tilted and withdrawn like in open-heart surgery.
All of the surgeon's hand movements are translated in real- time to the surgical instruments in the operative field.
Both the instrument shaft and the tip can be re-oriented and adjusted.
If released the instruments hang perfectly still.
The system is endowed by a "motion scaling"
software, which translates large movements in extremely precise micro-movements and by a tremor filter to maximize the surgical precision.
However, lack of tactile feedback is a limitation of this robotic system at present.

CLINICAL APPLICATIONS

Robotic technology has been used for coronary artery by-pass surgery (CABG), closure of atrial septal defect (ASD) and mitral valve repair.
In order to minimize risk to the patient associated with a radical new technology, robotics programs have been generally introduced gradually with caution and, keeping always in mind the possible need of conversion to conventional surgery.
Endoscope harvesting of the left internal thoracic artery (LITA) is the most common clinical application of robotic technology in cardiac surgery.
This procedure is carried out following the insertion of the endoscope and robotic instruments into the left hemithorax through the appropriately selected intercostal spaces.
In patients with single-vessel disease who undergo a minimally invasive direct coronary artery bypass (MIDCAB) procedure (namely a LITA to LAD anastomosis), the endoscopic LITA harvesting using a robotic system allows minimization of the incision and may help to reduce the pain associated with excessive rib-spreading necessary for LITA takedown under direct vision.
In many patients with multivessel disease undergoing revascularization through a sternotomy, the endoscopically harvested LITA has been successfully anastomosed to the LAD using either the “da Vinci” or Zeus telemanipulation system (10,11).
In Dresden, Germany, the “da Vinci” device is currently routinely used for endoscpic bilateral thoracic artery takedown, followed by multivessel revascularization using the so- called Dresden technique [left anterior minithoracotomy in the third intercostal space, direct aortic cannulation, institution of cardiopulmonary by-pass and cardioplegic arrest of the heart] (12).
This approach is particularly attractive for diabetic patients in whom harvesting of both thoracic arteries through midline sternotomy is associated with a not negligible prevalence of wound complications.
The first successful case of totally endoscopic coronary surgery (LITA harvesting and LITA to LAD anastomosis) has been reported by Loulmet et al.
(13)
For this operation, the endoscope is inserted at the 4th intercostal space in the anterior axillary line and the instrument ports are usually created at the 3rd and 6th intercostal space slightly anteriorly.
The LITA is dissected as a pedicle from the first rib to the 6th intercostal space using low- energy cautery. The LITA to LAD anastomosis is performed during cardioplegic arrest of the heart using the Port-Access system for cardiopulmonary by-pass and aortic occlusion.
Totally endoscopic LITA to LAD anastomosis using robotic instrumentation is currently carried out in a number of institutions with a variable proportion of conversion (14,15).
Recently, the same procedure has been performed on the beating- heart, using a stabilizer inserted through an accessory port (16-20). Successful totally endoscopic revascularization of two vessels (LAD and RCA) has been carried out.(21).
Closed chest closure of ASD has been carried out in some institutions using the “da Vinci” system (21,22).
For this procedure, femoral and jugular vein cannulation and the Port-Access method for closed-chest cardiopulmonary by-pass are required.
With appropriate robotic instruments, the pericardium is opened longitudinally and both venae cavae are dissected and temporarily occluded by snared tapes.
Following cardioplegic cardiac arrest, the right atrium is opened and the intracardiac defect is corrected. Rapid postoperative recovery along with excellent cosmetic result has been reported.
The “da Vinci” system has also been utilized in mitral valve reconstructive surgery.
Mohr et al in Leipzig has accumulated the largest experience this field (23).
During the last few years, Chitwood in the USA has been performing operations on a substantial number of patients with mitral insufficiency (personal communication) through a small thoracotomy.
The operation is not totally endoscopic, since a small thoracotomy in the 4th intercostal space is required, similar to that used for minimally invasive mitral valve repair.
The three dimensional videoscope is inserted through the incision, while the robotic instruments are advanced through two additional ports in the 2nd and 6th intercostal spaces in the midaxillary line.
Mitral repair has been accomplished following adequate exposure of the valve with a variety of techniques, including quadrangular resection, prosthetic ring implantation and “edge-to-edge” repair.
Recently, Lagne et al were able to avoid the small thoracotomy and performed the first completely endoscopic mitral valve repair using
the “da Vinci” telemanipulation system (24).
Mohr and Chitwood have described other successful totally endoscopic mitral valve repair (23).

THE SAN RAFFAELE HOSPITAL EXPERIENCE

From November 1999 to August 2000 the “da Vinci” Intuitive Surgical System has been used in our Institution in 42 cardiac surgical procedures (Table 1).
In 31 patients the robotic system was successfully utilized for LITA harvesting.
In 11 of these patients the operation was completed with a small left anterior thoracotomy to perform the LITA to LAD anastomosis on the beating heart (MIDCAB).
In 19 patients multiple conventional CABG procedure was carried out through midline sternotomy.
In 1 patient, the Dresden technique has been applied to perform a multivessel revascularization. All patients who underwent a MIDCAB procedure were angiographically controlled postoperatively, and graft patency with well-functioning anastomosis was invariably documented.
After an initial learning curve, the procedural time for LITA harvesting has been substantially reduced and is now around 30 minutes.
We have used the robotic system to treat 5 patients with an ostium secundum ASD and 2 patients with a patent foramen ovale and an aneurysm of the interatrial septum who presented after recurrent episodes of cerebral embolism.
All the procedures were carried out totally endoscopically and no complication was observed. The mean aortic cross-clamp time was 63±22 minutes and the mean cardiopulmonary by-pass time was 102±40 minutes.
Successful closure of the ASD has been documented postoperatively in all patients.
All patients were discharged from the hospital 6 days after the operation, with the patients immediately resuming their normal life style.
Finally, 4 patients with mitral insufficiency underwent mitral valve repair using robotic instrumentation along with a small thoracotomy in the 4th intercostal space.
In 3 patients a perfect competent mitral valve was created using the edge-to-edge technique, while the fourth patient required a reoperation during the same hospitalization to correct residual mitral incompetence.

DISCUSSION

Preliminary results in cardiac operations using currently available robotic systems show that computer- enhanced surgery is safe.
Although the possibility of prompt conversion to conventional surgery is ever-present, preliminary experience has not shown patients to be exposed to additional operative risk.
While a substantial proportion of conversions is reported, mortality and relevant morbidity are negligible.
The quality of computer- enhanced surgery seems to be similar to that offered by conventional surgery in terms of graft and anastomosis patency (25), effective ASD correction (21,22), and mitral valve repair (9,23).
In addition, rapid postoperative recovery and excellent cosmetic results are invariably reported. Procedural times, however, still exceed those required in conventional surgery, and this is an important limitation of robotic surgery at the present time.
Only a few cardiac operations are currently performed with the help of robots.
In coronary surgery, almost exclusively single- vessel revascularizations of the anterior wall are performed, and only the simplest intracardiac operations are carried out.
Endoscopic harvesting of the internal thoracic arteries is a useful application of robotic technology in coronary surgery, particularly when a MIDCAB procedure or a Dresden approach is planned.

CONCLUSION

The early experience with computer-enhanced telemanipulation systems throughout the world has been exciting.
Although many limitations have been observed, it is hoped that improvements in computer software will overcome these limitations.
With further refinements and the development of adjunct technologies, the technique of computer-enhanced endoscopic cardiac surgery will evolve and may prove beneficial for a larger patient population.

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