Augusto D’Onofrio, Gino Gerosa
Division of Cardiac Surgery, University of Padova, Padova, Italy
The development of new techniques for the treatment of almost all structural heart pathologies that do not require cardiopulmonary bypass and aortic cross-clamping, such as transcatheter aortic valve
replacement and transapical mitral chordae implantation, define a new age of our specialty: the micro-invasive (μICS) cardiac surgery era.
The Journal of Heart Valve Disease 2015;24:528-530
The technical evolution that has occurred during the past two decades now enables cardiac surgeons to perform almost all operations through a minimally invasive approach. Aortic valve replacement (AVR), as well as root and ascending aorta replacement, may be performed through an upper ministernotomy or second intercostal space minithoracotomy with either central or peripheral cannulation. The development of sutureless aortic valve prostheses has made minimally invasive AVR simpler and faster, thus potentially setting it as the new standard in the very near future. There are many centers worldwide that now routinely perform robotic or video-assisted mitral valve operations using port-access techniques. The final goal of minimally invasive cardiac surgery (MICS) is to accomplish cardiac operations through the smallest possible skin incision, thus reducing blood loss, pain, functional impairment and rate of wound dehiscence, ultimately leading to better cosmetic results, a faster postoperative recovery and overall better results if compared to conventional cardiac surgery.
Despite these potential advantages, many surgeons still prefer to perform conventional operations, since the learning curve and the complex set-up of a MICS program in terms of time as well as human and financial resources might not be counterbalanced by the clinical outcome. In fact, there is no evidence in the literature showing a clear superiority of MICS over conventional surgery. MICS still requires cannulation of the great vessels, cardiopulmonary bypass (CPB) and aortic cross-clamping that are all known to have a non-negligible impact on the patient’s body. In particular, CPB generates a systemic inflammatory response with the production of cytokines and potential harmful effects (1) on organ function, while the aortic cross-clamp time has been independently associated with mortality (2). This is particularly evident in patients who are in a poor clinical condition preoperatively.
Recently, many techniques that require neither CPB nor aortic cross-clamping, and which often may be performed in a totally percutaneous fashion, have been developed in order to treat the same diseases addressed by MICS. Transcatheter aortic valve replacement (TAVR) may be considered one of the biggest breakthroughs in cardiac surgery, as it enables the implantation of an aortic valve prosthesis on the beating heart, with no need for CPB. Moreover, if it is performed through a transfemoral approach there is no need for general anesthesia and intubation. TAVR has shown excellent early and mid-term results (3) and, when compared to surgical aortic valve replacement (SAVR) in selected patients, it has proven to be non-inferior (4) or even better (5). Similarly, a new technique for transapical beating heart mitral valve repair with artificial chordate implantation has been recently developed, with initial promising results (6). Furthermore, transcatheter percutaneous edge-to-edge mitral valve repair is now a well-established procedure with good early and mid-term results (7).
Transcatheter mitral valve replacement has already been performed in humans, and hopefully will soon be readily available (8).
It goes without saying that these new procedures clearly are much less invasive than MICS as they are done a) on the beating heart, b) with no need for CPB, c) in a totally percutaneous fashion or with a very small skin incision, d) after with local anesthesia only and e) using multimodality imaging techniques. Therefore we propose to include these new entity: MICRO-INVASIVE CARDIAC SURGERY (μICS) era. We need to understand that this is not a futuristic visionary scenario – it is already happening, and it is reality. Thinking that μICS would be just reserved to a restricted number of inoperable patients and that, ultimately, cardiac surgery would never change its basis would be an unforgivable error for us, and in particular for our young fellows. Therefore, we need to rethink our vision of cardiac surgery and be ready to reshape our mentality. Let us consider interventional cardiologists. The diagnostic role is now just a marginal part of their practice, and it will be probably even more marginal in the future. Coronary computed tomography (CT) will soon replace diagnostic coronary angiography; three-dimensional echocardiography, nuclear magnetic resonance and cardiac CT-scanning are already able to answer to the great majority of diagnostic dilemmas. Today, interventional cardiologists routinely treat structural heart diseases as interatrial septal defects, left atrial appendages, aortic valve stenosis and mitral valve regurgitation. All of these procedures should be considered as μICS, and that being said, interventional cardiologists might be considered part of the minimally invasive cardiac surgeons’ tribe. In fact they are much closer to surgeons than to clinical cardiologists, due to the fact that they perform procedures which treat structural heart diseases.
Now, where is the border between cardiac surgery and interventional cardiology? Is it just a matter of catheter skills? Do we really believe that it’s going to be impossible for a surgeon to manipulate guidewires after an appropriate training? Will there be really a difference between cardiac surgeons and interventional cardiologists within the next 20 years? Time will tell, but it’s already time to think about it and be ready for these changes. Here are some reflections. First, interventional cardiologists and cardiac surgeons now have the potential to work in the same department rather than in two different divisions, as they both treat structural heart diseases. There would be an enormous advantage with this new organization. It is clear - though many would never admit it - that today’s cardiologists and surgeons are fighting for patients. The PARTNER trial and the SYNTAX trial, and the way in which these have impacted on the real world, are clear examples of that. The choice of procedure for a patient is often biased by the limited option that a department, or a physician, has to treat a disease, or by who is seeing the patient first, whether a surgeon or a cardiologist. For example, an interventional cardiologist could encourage a patient with a three-vessel coronary artery disease to undergo a percutaneous revascularization while they are already in the catheter laboratory, even if that particular patient would have gained more benefit from a coronary bypass operation. On the other hand, a cardiac surgeon who doesn’t perform TAVR could suggest AVR to a high-risk patient, even if that patient would have more likely benefitted from a micro-invasive transfemoral TAVR. The possibility of making surgeons and cardiologists work together not only in a Heart-Team but also in a Structural Heart Disease Department means no bias any longer, and also means a choice of the best treatment for every single patient, whether conventional surgery, MICS or μICS.
Second, we should implement cardiac surgery training with catheter-based techniques and percutaneous structural heart operations. Whilst our generation will probably be only marginally affected by this ongoing revolution, for our fellows who are about to start their individual practice in the next four or five years this is going to be a big deal. The absence of catheter skills in their training would have detrimental effects, as it would reduce their chances of having an active role in this new era of μICS that they strongly deserve for their passion, sacrifices and commitment to the job.
Third, a completely equipped hybrid operating room should be the place where μICS is performed. Safety during these procedures should be the most important issue. This achievement requires up-to-date technology, teamwork, multidisciplinary assessment, and also a timely identification and treatment of complications that, especially in μICS, might easily be fatal. During conventional surgery we are used to managing intraoperative complications with the use of CPB, as we have a visible direct access to the great vessels; however, this is not always possible during μICS. The institution of CPB in μICS procedures may be challenging, as there is no direct access to the great vessels, which are often heavily diseased. For this reason, preoperative planning and intraoperative treatment by skilled physicians is mandatory, and it is impossible to imagine performing such complex procedures in a conventional catheter laboratory by operators with no experience in CPB institution and conversion to conventional surgery.
In conclusion, we are facing a new era of structural heart disease treatment. Micro-invasive cardiac surgery enables the treatment of many diseases through operations that do not require CPB and often do not require general anesthesia and skin incisions. This would make the difference between interventional cardiology and cardiac surgery almost undetectable. There would simply be a wide spectrum of procedures, from conventional open-heart surgery to μICS passing through MICS, and we should be intelligent enough to accept the situation, understand it, and change our vision for our future and for the future of our fellows. A ‘paradigm shift’ has been described by Thomas Kuhn as a scientific revolution: a change in the basic assumptions, or paradigms, within the ruling theory of science (9). We cannot reject the evidence that μICS is already part of our daily practice to posit the never-ending superiority and immortality of traditional surgery. We, as cardiac surgeons, should be part of this new era with no fear of losing our identity as our dedication to technologic advancement has made possible all the incredible achievements so far. It is now time to try even harder, as we are probably facing the greatest scientific revolution in our community since the invention of extracorporeal circulation.
Dr. A. D’Onofrio is physician proctor for Edwards Lifesciences.
1. Esper SA, Subramaniam K, Tanaka KA. Pathophysiology of cardiopulmonary bypass: Current strategies for the prevention and treatment of anemia, coagulopathy, and organ dysfunction. Semin Cardiothorac Vasc Anesth 2014;18:161-176
|Editorial: Shifting a Paradigm of Cardiac Surgery: From Minimally Invasive to Micro-Invasive|
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