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Medical Meeting Reports

American College of Surgery Clinical Congress

October 10-15, 1999


COMPUTER-INTERFACED MICROSURGICAL ROBOTS MAY MAKE MINIMAL INVASIVE ENDOSCOPY A REALITY FOR CARDIAC SURGERY
font=>By Paul Recchia, Ph.D.

R. Damiano, MD, Penn State, Hershey, Pennsylvania, presented results of work with robotic assistance to enable endoscopic cardiac surgery.

The Quest for the Holy Grail

The revolution in minimally invasive surgery has had minimal effect on cardiac surgery, because of the issues that result from performing procedures "off-pump" -- without a heart lung machine on a beating heart. At present, only a small percentage of patients (less than 5%) with coronary artery disease are treated at major centers with Off-Pump Coronary Bypass Grafting (OPCBG) and 20% of coronary bypass graft procedures in the US are performed off-pump. Now, however, there is a movement toward minimally invasive endoscopic surgery with robotic instruments.

The Challenges to Overcome

Traditional endoscopic surgery on the beating heart is almost insurmountably difficult and rarely performed. The fixed parts of standard endoscopic tools make it hard to access vessels around the heart; cardiac movement makes it difficult to focus precisely; and, because of their length, traditional endoscopic tools magnify tremor, limiting dexterity.

A Possible Answer: Computer Interface Microrobotic Instrumentation

The emerging technology of medical robotics may provide an new approach to minimally invasive procedures on the heart. The computer-intermediated instruments closely mimic the dexterity of the human wrist in positioning instruments, thereby eliminating tremors. New imaging systems provide cardiac surgeons with a 3-D field of vision. The new systems have particular applicability to cardiac surgery.

Animal Study

Dr. Damiano first demonstrated the feasibility of microsurgical robots in bypass graft procedures on cows. The endoscopic minimally invasive procedure (MIP) set out to correct experimentally-induced occlusions of the left anterior descending (LED) coronary artery, followed by anastomosis of the left internal mammary artery (LIMA) to the LED. The endpoints of the study were blood flow and ventricular function. The time to perform the anastomosis were within an acceptable range. The animals survived 4-6 weeks. These results were presented to the FDA, and the investigators were allowed to proceed with a clinical trial on humans.

Clinical Trial

The initial protocol design for bypass graft procedures with a minimally invasive robotic system was a prospective, nonrandomized, single-center trial. Recently additional centers in the US were added to the trial. The study was approved for 20 patients; results were shown on the first 15 patients. The average patient was 59 years of age, there were 10 males, 5 females, and there was an average of 2.5 grafts per patient. Average setup time was 15 minutes. The MIP was a modified subzyphoid approach with three ports of entry. The fastest surgery time was 17 minutes. A 10-week follow-up was performed on all patients. Results: 87% (13/15) grafts demonstrated excellent flow. Average ICU stay was one day; average length of stay was 4 days.

Conclusion

Dr. Damiano concluded: "There is a tremendous potential for how computer systems can enable surgeons to perform new operations otherwise stunted by technical and human limits. We are potentially limited only by our imaginations as to what these technologies can do as they become more and more affordable." He predicts that advances in medical robots will make off-pump cardiac surgery a common procedure. Studies are now underway around the world on beating heart.

Ortho Biotech

Funded through an unrestricted educational grant by Ortho Biotech.



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