In LVAD patients, a postoperative process that
will provide adequate LVAD flow and tissue perfusion
can be ensured with careful intraoperative anesthesia
management, and patient hemodynamics will be
less affected by the underlying pulmonary and right
ventricular dysfunction.[
6,
7] The first step in patient
management during anesthesia preparations is advanced
hemodynamic monitoring. In patients with advanced
heart failure, a decrease in left ventricular preload
or an increase in left ventricular afterload can cause
rapid hemodynamic decompensation.[
8] These patients
require large amounts of circulating catecholamines
to maintain vasoconstriction.[
9,
10] Suppression of the
sympathetic system during induction or maintenance
of anesthesia may cause severe decompensation
in this patient group.[
11-
13] In patients undergoing
LVAD implantation, TEE is a useful diagnostic and
monitoring tool that provides insight into the position
of the access cannula, ventricular contraction, filling
pressures, and valve functions.[
14-
16] In our patient
series, all patients underwent perioperative a TEE
examination.
Evaluation of right ventricular functions is of
particular importance.[17] Right ventricular function
is affected by preload, PVR, and contractility. Upon
initialization of the LVAD device, right ventricular
preload increases, and left ventricular afterload can
be optimized by adjusting the device flow. After the
LVAD is implanted, the ventricular septum should
be in a neutral to left position with the left ventricle
moderately decompressed. Insufficient left ventricle
decompression causes rightward septal shift and a
decrease in LVAD flow, while excessive ventricular
decompression causes the septum to deviate to the
left and the device to suction, compromising the
contractility of the right ventricle.
The interventricular septum may deviate to the left,
impairing the septal contribution to right ventricular
contraction and causing RVF. When RVF develops,
it will increase left ventricular failure due to the septal
compound system.[18] Therefore, visual control with
TEE gains importance during the termination of
CPB to assess the need for fluid and inotropic support during the incremental raising of the LVAD flow.
The presence and degree of RVF can be successfully
defined with monitoring and TEE examination.
Although various definitions of RVF and risk
scoring systems have been defined, there is no
standard accepted classification that guides treatment
algorithms.[19] Existing definitions are generally based
on the treatment of RVF. High dose and duration
(more than two weeks) inotropic support RVAD,
ECMO, and long-term use (two to 14 days) of inhaled
nitric oxide are indicated as RVF treatment.[20-22]
Clinical differences are common in the detection
and management of intraoperative RVF. Although
the general strategies are known, the literature
on treatment combinations, timing, and doses is
limited. In our algorithm, patients were classified
as mild, moderate, and advanced RVF by evaluating
postoperative hemodynamic parameters (MAP,
CVP, and PCWP), echocardiographic parameters
(TAPSE, right ventricular fractional area change
[RVFAC], interventricular septum position,
and tricuspid valve function) and preoperative
echocardiographic findings. Patients were managed
according to this evaluation of RVF. The main
purpose of the treatment algorithm was to optimize
preload, afterload, and contractility using pulmonary
vasodilators and inotropes. The requirement of
inotropes or mechanical support was determined
according to these parameters.
Inotropes, such as milrinone, or pulmonary
vasodilators, such as nitric oxide and iloprost (PGI2
analogue), support the right ventricle by reducing
afterload and optimizing preload.[23] Inhaled nitric
oxide can produce a 43% reduction in PVR and
decrease transpulmonary gradient (TPG).[24] In our
patients, 20-30 ppm nitric oxide was used in 38
(46.34%) patients. In addition, hypoxia, hypercarbia,
and acidosis should be avoided to minimize PVR.[18]
Right ventricular failure after LVAD is encountered
in 5 to 44% of operated patients across studies that
use varying definitions of RVF.[25] Advanced RVF was
detected in three (3.6%) of our patients, moderate RVF
in 12 (14.6%) patients, and mild RVF in 48 (58.5%)
patients. Due to varying definitions of RVF, no
comparison with other studies could be made in this
respect. The vasoactive inotropic scoring system is an
objective indicator of inotrope therapy. Many studies
have shown a correlation between high VIS values and
poor outcomes.
Albeit, cut-off values for VIS vary greatly between
studies.[26] In a study conducted in adult cardiac
surgery patients, one-year mortality was higher in
patients with a VIS ≥30.[27] In a study on the
prognostic value of VIS after LVAD implantation,[28]
high postoperative VIS (≥20) was associated with
adverse in-hospital outcomes and was a good predictor
of in-hospital mortality. In our study, the mean VIS
value was 25.7±1.3 in patients with advanced RVF,
19.5±1.5 in moderate RVF, 10.8±1.6 in mild RVF,
and 3.6±1.1 in patients without any RVF. Both RVF
and mortality are more frequent with high VIS
values. The necessity of using RVAD after LVAD is
reported as 2.6%.[29] In The European Association For
Cardio Thoracic Surgery, (EACTS) expert opinion
statement, it was revealed that RVAD was required
at a rate of 6 to 28% in patients using LVAD.[30] In
our series, RVAD was used in one (5%) of 20 patients
with moderate and severe RVF. Two patients with
advanced RVF could not be weaned from RVF,
and RVAD, which is the next treatment step, could
not be used due to sepsis and multi-organ failure.
Right ventricular failure after LVAD implantation
is associated with high mortality and morbidity.[22]
The RVF development rate is 9 to 42% after LVAD
implantation,[22] and the mortality rate is stated to be
8%.[30] In our patient series, the mortality rate was
25% in patients with advanced RVF and 8.3% in
patients with moderate RVF. When RVF is excluded
from grouping, mortality is 9.7% in all patients.
The limitations of this study include its
retrospective data collection and the relatively limited
number of cases. Due to the limited number of
patients with different grades of RVF, a statistically
significant comparison was challenging. However,
we believe it is important that the same treatment
algorithm is applied to all patients, and thus we aimed
to share our intraoperative patient management to
form a basis for prospective studies.
In conclusion, intraoperative management during
LVAD implantation requires a multidisciplinary
approach and is crucial in the presence of RVF. A
standardized method for defining the RVF severity
and a well-defined treatment protocol according to its
degree of severity is lacking. Defining the degree of RVF
is essential to provide optimal treatment. We suggest
our definitive criteria for evaluating mild, moderate,
and severe RVF after LVAD implantation, which is
helpful for a stepwise approach to management. The
clinical criteria proposed here can be helpful for future studies aiming at a universal algorithm for defining
the management of RVF after LVAD implantation.
Ethics Committee Approval: The study protocol was
approved by the Dr. Siyami Ersek Thoracic and Cardiovascular
Surgery Training and Research Hospital Ethics Committee
(Date/no: 08-03-2021/E-28001928-604.01.01). The study
was conducted in accordance with the principles of the
Declaration of Helsinki.
Patient Consent for Publication: A written informed
consent was obtained from each patient.
Data Sharing Statement: The data that support the
findings of this study are available from the corresponding
author upon reasonable request.
Author Contributions: All authors contributed equally
to the article.
Conflict of Interest:The authors declared no conflicts
of interest with respect to the authorship and/or publication
of this article.
Funding: The authors received no financial support for
the research and/or authorship of this article.