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.
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