CD&D Contributing Writer
Robotic-assisted, minimally invasive cardiac procedures avoid the drawbacks of traditional heart surgery, such as the blood loss, pain and scarring that typically results from cutting through the breastbone or opening the ribs.
Since 2006, Christine McCarty, MD, chair of cardiac surgery at Pinnacle Health Community Hospital (Harrisburg, Pennsylvania) has performed more than 100 surgeries with the da Vinci robotic system from Intuitive Surgical (Sunnyvale, California), bannered as reducing the chance of infection, shortening hospital stays and improving recovery times.
In a recent webcast, McCarty demonstrated also how the da Vinci surgical system enables more precise minimally invasive coronary bypass.
Seated at a console a few feet away from the patient, a surgeon views a 3D image of the surgical field and uses mechanical "hands" to translate the surgeon's movements into more precisely targeted movements of the surgical instruments.
A condensed video of a six-hour beating-heart surgery performed by McCarty was introduced by moderator John Pennock, MD, describing the patient as an otherwise healthy 59-year-old man who had experienced chest pain. A stress test and heart catheterization revealed abnormal vascularization of the lateral wall of the heart and 100% occlusion of the circumflex.
"The left anterior descending artery is very small and his left diagonal is also blocked," Pennock says.
The surgery involves the traditional approach of using mammary arteries dissected from the chest wall as grafts to replace the blocked vessels and bring blood back to the heart muscle, traditionally done by cutting open the sternum and employing heart-lung bypass. Using the da Vinci system, however, McCarty can do this via three small ports: one for a 3D camera, two for the left- and right-hand instruments.
Needed: a special team
McCarty says that "a special team [is needed] to make this dream operation a reality," noting that her team, including an anesthesiologist — "who gives us some really special techniques" — has been together for two years.
The small openings are made posteriorly to the heart, the trocars are inserted, and CO2 is used to force the lung back from the field of view.
"This surgery is ideal for left-sided revascularization," McCarty says, "but right-sided work is a little dicey with robotics."
After placement of the trocars, McCarty moves away to the da Vinci. By manipulating its operating controls, she directs a tissue forcep with one hand, an electrosurgical dissector with the other and activates the electrosurgical energy with her foot on a pedal. Her movements translate to the robot's hands instantaneously.
An assistant nurse practitioner at the patient's side changed the instruments in the robotic arms at McCarty's request.
An Internet question: "How is the feel and touch of what you are doing?"
Visual senses take over for tactile
McCarty explains: "Your senses take over in a different way. Tactile impressions are replaced with improved visualization."
She continues her explanation: "The heart is rotated slightly to the left due to the deflated lung. We are now confident that the vessel graft will be adequate, so we start taking down the diseased arteries.
"Then we isolate the right internal mammary artery (IMA), and when that's clean and free we will take down the left one. This is like a Navy pilot landing a plane on a moving ship. We have a moving heart and a moving field."
McCarty acknowledges a steep learning curve for the robotic revascularization approach, saying it should be done only by "a proficient off-pump surgeon," and adding: "Only in this last year have we been completely confident in our ability to treat all varieties of patients with this technique."
Using small titanium clips to prevent bleeding, McCarty dissects the IMA free of its veins and completes the dissection. With the IMA fully dissected it is clipped proximally and becomes a free graft. It is removed from the field and tested at the surgical table to be sure it is leak-free.
Then the left IMA is approached, the proximal end left untouched so blood flow will come through it from its normal channels. Instead of using RF energy, significant branches of the IMA are clipped so that thermal energy transfer to the IMA is minimized.
The clips are loaded and placed in the robotic arm by assistants. McCarty calls for a scissors, and a slight nudge of the robotic arms by the assistant signals the exchange of instrumentation.
"This left IMA really needs to be preserved in some ways," McCarty says. "It is a survival benefit to the patient. No other conduit will replicate the results from the IMA to the left anterior descending artery of the heart."
The best candidates
Pennock says the best candidates for the procedure "are those with left-sided lesions of the coronary arteries and stentable right coronary arteries. We are comfortable with the use of hybrid revascularization where the cardiologist manages some vessels and the surgeon manages some.
"There are usually some vessels too small for surgery but ideal for stent placement."
McCarty has prepared both IMAs for anastamosis, and after the robot is pulled back from the surgical field, she does a standard, minimally invasive revascularization.
The camera port is enlarged slightly to allow a 3" retractor to be inserted to help stabilize the heart. The pericardium is opened to find the target arteries and verify their condition. Wearing surgical loupes, McCarty takes the free graft from the table, the right IMA marked with dye to show a straight line so that twisting does not occur. She is then performs a T (artery to artery) anastamosis.
A questioner asks about the difficulty of switching between the robotic and open surgery methods.
McCarty says that fine dexterity "is somewhat lost when you move back to open, but I am able to brace the instruments so the impact of this is minimized to the patient."
The T part of the graft right IMA is then sewn to the circumflex artery and the left IMA to the diagonal artery.
"Before we leave," McCarty explains, "we use the Spy intraoperative angiography system from Nova-daq Technologies [Toronto] to test the patency of our anastamosis. We use fluorescein dye. We inject 1 cc with 10 cc normal saline bolus. We bring the camera back in and are able to fluoresce the dye on a low level laser camera. The anesthesiologist injects the dye and the bolus.
The whiteness of the right IMA connects to the circumflex and the real-time flow of the vessel shows that the graft is patent." She highlights the importance of this because of the small incision and limited field of vision. "It takes about three minutes to do this test."
The small chest incision is closed traditionally and the patient awakens and is moved to the recovery area. Pennock concludes: "The big advantage to the patient here is the very small chest incision. Post-op pain will be minimized and breathing will not be painful as with a split sternum incision." She adds: "Coughing and deep breathing is very important to prevent pneumonia and other complications post-operatively."