Minimally invasive valve surgery — that just does not roll off the tongue like “robotic” surgery. The robot stands for the Da Vinci telemanipulator and is one of the great successes of modern marketing in medicine. Initially developed to give excellent 3-dimensional visualization along with the ability of remote surgical manipulation, the Da Vinci robotic platform has been well adapted to prostatectomy surgery. The hope early on, was that this would expand to other areas such as general surgery, cardiac surgery, etc. The adoption and utilization of the Da Vinci robot in cardiac surgery has been slow. However, the learning curve required to achieve some degree of control with the robot, has enabled many surgeons to think of and train in minimally invasive valve surgery procedures.
Minimally invasive approaches in cardiothoracic surgery have to weighed in balance – safety is paramount when dealing with the major blood vessels, heart and lungs within the chest. This explains the reluctance of many practicing and experienced surgeons in adopting smaller incisions in cardiac surgery. The video-assisted thoracic surgery (VATS) revolution transformed many aspects of esophageal and lung surgery in the 1990s and has recently expanded to include lung resection.
Minimally invasive cardiac surgery made its first appearance in the early 1990s in the form of MIDCAB (minimally invasive direct coronary artery bypass). This utilized a mini-thoracotomy on the left side of the chest. Unfortunately, there were efficacy issues with the procedure and a significant amount of pain with that approach which prevented widespread adoption.
Over the next 15 years, the principles of the approach were modified and used to provide access to the mitral and tricuspid valves, while cardiopulmonary bypass support was provided by peripheral cannulation. Which brings us to the present – increasing numbers of minimally invasive cardiac procedures are being carried out to a great degree of success with the same safety profile as standard open procedures in selected centers by groups and teams that have built experience.
So, while the marketing imperative of being able to perform these procedures with less morbidity exists, there are some centers that have excellent results with these techniques. It is important that you find the right center for your procedure and be comfortable with them.
So, as consumers (patients, referring physicians, etc), these are the questions you have to ask of the surgeon/surgical team?
1. How many of these procedures have you done?
2. How long have been doing them?
3. What alternative procedures exist if the minimally invasive procedure fails?
4. Is the team comfortable performing these procedures?
5. What measures are used for pain relief?
6. When are these approaches not suitable in your particular circumstance?
7. How often will the patient be seen by an attending physician or a doctor?
8. What are the mechanisms of follow up?
How then do we perform these minimally invasive heart valve procedures?
This is an approach where a small incision of between 5 and 10 cm is made on one side of the chest, usually on the right side of the chest. Access to the heart is facilitate by clearing muscle off the underlying ribs. This potential gap between the ribs is spread to provide entry into the chest on that side. Depending on the location of this incision, the surgeon can directly access the aorta, right atrium and left atrium. This image below shows the retractor placed in between the ribs to provide access to the heart and structures within the chest. To allow safe operations on the heart, the patient is connected to the heart lung machine through incisions in the groin through which cannulae or tubes are inserted into the blood vessels there.
An incision below and lateral (away from) from the right nipple, which is typically under the breast in female patients provides potential access to the mitral and tricuspid valves.
An incision higher up, extending laterally from the midline is more typically used to approach the aortic valve. This incision while less invasive in terms of bone cutting, can be limited in terms of the quality of access to the aortic root. If for some reason, the aorta is very rigid and calcified, this incision would provide a limited view. In addition, if some procedure needs to be done on the ascending aorta (such as a replacement or repair), the minithoracotomy incision may not be adequate. Almost always, one or two ribs need to be dis-articulated or disconnected from the sternum to allow the access into the chest. That aspect is well tolerated and is not associated with significant pain or discomfort. However, the other factor may be that access to the rest of the heart is rather limited.
The full sternotomy where the sternum is divided from top to bottom is a complete incision in terms of maximal access and allows very complex cardiac procedures to be performed. There is some obligatory blood loss from oozing from the marrow as the cut edges are exposed. A common complication after cardiac surgery is bleeding and most of the bleeding arises from the sternum. The down-side to this incision is that the bone has to be approximated very carefully at the end and takes about 12 weeks to heal completely. Complications of this wound can have devastating consequences. Smaller versions of the sternotomy therefore have been proposed and used with great success. The lower mini-sternotomy is occasionally used to perform mitral and/or tricuspid valve procedures.
The upper mini-sternotomy provides excellent access to the aortic root, dome of the left atrium, and pulmonary artery. To avoid fixing an irregular bony incision, these incisions were often limited to a ‘J’ or reverse ‘L’ configuration in the upper mini-sternotomy. Approximating the bony fragments at the completion of the procedure may however, be not be entirely accurate. To expand the capability of the mini-sternotomy and allow reliable fixation at the end, we have promoted the use of inverted T shaped mini-sternotomies. The bony parts of the sternum can be approximated accurately and securely fixed with plates.
Robot Assisted Procedure
The Da Vinci Robot was developed by Intuitive Surgical, Mountainview, CA. This is a telemanipulator with excellent near 3-dimensional visualization utilizing a sophisticated scope which can be inserted a 12 mm port. The manipulating arms can be inserted through additional 10 mm ports. The actuation of the arms and the visualization is at a console that is remote from the patient and requires a patient side surgeon or assistant to help insert specific instruments and scopes through the ports. This robotic system is expensive and takes time to set up. There is also no tactile feedback and all manipulations have to be evaluated by visual cues. The field of vision is limited. The advantage of this system is the potential of performing complex procedures through small port sized incisions. The reality is that there is a significant learning curve that few surgeons manage to overcome without unfettered access to the robot. There is also the matter of the cost involved. In addition to the outlay of the robot, which is over 1.5 million dollars, there are multiple recurring expenses. For instance, each of the instruments can be re-used only 10 times, which accounts for further cost escalation. Regardless of the expense, learning curve and loss of tactile feedback, robotic procedures have been little more than a marketing ploy for certain centers. That may seem cynical but there are definite limitations to the utility and scope of the Da Vinci robot in cardiac procedures. In the setting of valve procedures, it is possible to perform relatively straightforward repairs of the mitral valve. However, valve replacements seem very difficult and almost impossible with robotic assistance.
When the Da Vinci robot failed to live up to its promise in the cardiac arena, found a prominent niche in urology in prostatectomy. A recent report in the JAMA studying outcomes with this approach on prostatectomies showed a significant cause for concern – despite some reduction in morbidity, the outcomes were equivalent to the open procedure in terms preservation of urinary continence and sexual function. One disturbing fact was the late incidence of strictures. A retrospective review of robotic experience at the University of Chicago, with a dedicated robotic cardiac surgeon and surgeon for over 18 months, showed that there was a significant increase in operative times. In terms of coronary artery surgery there was a definite incidence of late anastomotic complications that were difficult to address without a second open surgical procedure.
Regardless of the approach, the fundamental nature of surgery has to be to ensure a durable, excellent repair without harming the patient in any way. The quality of the cardiac procedure has to be at least as good as the traditional open procedure.