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3 . 2020

The future of cardiac surgery: minimally invasive VAD implantations

Abstract

In the last twenty years, left ventricular Assist Devices (LVADs) have evolved from rescue to regular therapy in the treatment of terminal heart failure. A widespread trend in surgery is the use of less invasive procedures. The reduction of surgical trauma is commonly known to reduce complications associated with large incisions especially blood transfusions or length of hospital stay and many patients request less invasive techniques. Since 2014 our centers main implantation strategy for LVADs is a minimal-invasive technique. In this article, we describe and discuss the bench to bedside development of the "Hannover Technique" which successfully enables surgeons to implant LVADs minimally invasively and has been successfully transferred to many centers worldwide.

Keywords:Left Ventricular Assist Device (LVAD), minimally invasive, implantation, Hannover Technique

Funding. The study had no sponsor support.
Conflict of interests. The authors declare no conflict of interests.
Contribution. Authors contributed equally.
For citation: Dogan G., Hanke J.S., Deniz E., Merzah A., Li T., Mariani S., Haverich A., Schmitto J.D.The future of cardiac surgery: minimally invasive VAD implantations. Clinical and Experimental Surgery. Petrovsky Journal. 2020; 8 (3): 17-20. DOI: https://doi.org/10.33029/2308-1198-2020-8-3-17-20

In the last twenty years, left ventricular Assist Devices (LVADs) have evolved from rescue to regular therapy in the treatment of terminal heart failure. In the past, devices were rather bulky and notwithstanding being life saving devices for many, the quality of life of the patients was severely impaired by heavy equipment and short battery capacity. The shift in strategy from pulsatile to continuous flow devices and consecutively from axial to centrifugal flow enabled engineers to decrease the size of the pump housings. While not being perfect devices, the current third generation of VAD has brought many innovations from bench to bedside such as artificial pulsatility, lighter equipment and extended battery capacities up to 18 hours resulting in increased survival rates as well of improved quality of life after VAD implantation.

A widespread trend in surgery is the use of less invasive procedures. The reduction of surgical trauma commonly reduces complications associated with large incisions especially blood transfusions or length of hospital stay. Additionally, many patients request less invasive procedures due to their cosmetically favorable results.

Lawrence Cohn was one of the pioneers in mini-mally-invasive cardiac surgery procedures. In the year 2009 and 2010 Prof. Schmitto had the honor to work with him during his stay at Harvard Medical School and was eager to learn new surgical techniques from him [1-3]. When Schmitto transitioned back to Germany to Hannover Medical School to work in the heart failure team with Prof. Martin Strueber, he was inspired to apply this knowledge to MCS surgery. Schmitto and Strueber started to brainstorm less invasive techniques for LVAD implantation and tested them eagerly in the animal laboratory. Ultimately, in 2011 we were successfully able to transfer the newly invented technique into human use.

The "Hannover Technique" for minimally-invasive LVAD implantation consists out of a hemi sternotomy combined with an anterolateral thoracotomy [4-11]. The original trick of this procedure is to tunnel the outflow graft intra-pericardially and spare a full sternotomy. Thus, the pericardium of the heart remains closed and there is no need to manipulate the position of the heart inside the thorax. Duirng the first years, this novel, innovative surgical technique faced a lot of criticism within the old conventional cardio-surgical world. Critiques said that the only benefit is sparing of the sternum, the risk of the minimal invasive procedure was initially declared to remain too high and the operation too difficult. However, only five-six years later, while gaining more and more experience at many different centers who where mainly trained in Hannover with this technique, the Hannover Team was able to show that there are indeed mayor benefits such as reduction of right heart failure and blood transfusions, the simplification of re-do procedures (including tunneling the outflow graft through the left pleural space) as well as a shorter in-hospital stay for patients after LVAD implantation.

Today, the Hannover Team successfully trained colleagues from all over the world in using the "Hannover Technique" and the technique successfully received CE mark (2016) as well as FDA approval (2018) for LVAD implantation. Therefore, the story of the "Hannover Technique" is an excellent example from bench to bedside implementation of a surgical technique which was being developed of Prof. Schmitto and Strueber's Team at Hannover Medical School (see figure).

The minially-invasive VAD-technique as described by Schmitto et al.

Example, in an actual issue of Artificial Organs two surgical centers describe their experiences with alternative LVAD implantation techniques. Ozer et. al from the department of cardiovascular surgery of the Kartal Kosuyolo Hospital in Istanbul, Turkey, present their experience with the transition from conventional technique to the less-invasive approach in left ventricular assist device surgery.

Kawabori et. al from the Division of Cardiotho-racic Transplant and Assist Devices from the Baylor College of Medicine in Houston, Texas, U.S.A. also report their experience of less invasive LVAD implantation technique as described by Schmitto at al. This group performed a retrospective study on eight patients who underwent LVAD implantation via a sternum sparing approach and outflow graft anastomosis to the descending aorta.

While both techniques impose a learning curve on surgeons, it is surely important to know about alternative techniques to conventional LVAD implantation and about their benefits to the patients [12-29]. Less-invasive LVAD implantation has become a standard in minimally-invasive and should be in the portfolio or every MCS surgeon. As shown in the article of Ozer et al. it is easily possible to transfer this technique into other programs with a steep learning curve. Anatomic variations like porcelain aorta or reoperative cases, challenging hemodynamics such as right heart failure or other challenges in LVAD surgery often require creative solutions. Therefore, it is important to be aware of alternative implantation techniques such as the anastomosis of the outflow graft to the descending aorta.

In the future, we will see many additional innovations in the design and function of ventricular assist devices. Pump miniaturization, transdermal power supply and improvements of hemocompatibility are suspected to even further improve outcomes and survival after VAD implantation. Thus, cardiac surgeons will continue to adapt implantation techniques to the new designs and possibly even further miniaturize VAD implantation.

References

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CHIEF EDITOR
CHIEF EDITOR
Sergey L. Dzemeshkevich
MD, Professor (Moscow, Russia)

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