Heart Transplantation and Ventricular Assist Devices
Heart transplantation and VAD patients face unprecedented challenges
during the coronavirus disease 2019 (COVID-19) pandemic. These
populations are at increased risk for acquiring COVID-19 infection. For
heart transplant (HT) clinicians, the global pandemic has unique
implications for patients, including those on the waiting list and
transplant recipients.
Many centres have inactivated most of their HT waiting list, reserving
active transplant status for only those patients with a presumed waiting
list mortality of 1 to 2 weeks, thus limiting transplant to patients in
tiers 1 or 2 of the new heart allocation policy. For listed patients who
are hospitalized without a strict contraindication to durable left
ventricular assist device implantation, LVAD as a bridge to transplant
may be a viable strategy to get at-risk patients home and out of the
hospital, minimizing their exposure to COVID-19. Left ventricular assist
device implants should not be performed in elective cases because of
resource constraints and potential for nosocomial infection.
The COVID-19 pandemic has had far-reaching implications for donor
selection, organ procurement, waiting-list candidates, and transplant
programmes.[30] Given the limitations of current testing and risks
for asymptomatic transmission and infection, the HT community must be
careful to select uninfected donors. As the pandemic continues to
evolve, a centre’s transplant volume may require staged reduction to
meet ITU bed, staffing, and medical equipment needs of the majority
nontransplant population.
Important decisions have already appeared about actively listed
patients. At any given time, a significant portion of patients are
waiting in-hospital for HT. These patients are at higher risk for
contracting the virus compared with others waiting at home. If they
subsequently contract COVID-19, they are at risk for more severe
infection because of their underlying health conditions, and risk
delisting. For listed patients, transplant centres should highlight the
waiting list mortality risk–benefit ratio and provide institutional
updates.
Left ventricular assist device patients are affected by long‐standing
cardiovascular diseases and subjected to variations of the normal
cardiovascular physiology, thus requiring an even closer monitoring
during the COVID‐19 outbreak. Potential deleterious effects of such a
situation can be a delayed recognition of LVAD‐related complications,
misdiagnosis of COVID‐19, and impaired social and psychological
well‐being for patients and families.
LVAD patients are at increased risk of COVID‐19 infection for several
reasons including most LVAD patients share the same risk factors for
COVID‐19 infection and represent a very vulnerable population. These
patients may manifest impaired immunity with increased risk for
opportunistic infections[1] and activation or enhanced release of
the inflammatory cytokines in COVID‐19 may augment the pre‐existing
myocardial injury.[31]This “functionally immunocompromised state”
increases susceptibility to complications from opportunistic infections.
Due to the general reorganization of healthcare resources in many
hospitals, elective LVAD implantations have been reduced to allow for a
higher availability of intensive care beds. Consequently, only patients
classified as INTERMACS profile 1 and 2 are being considered for LVAD
implantation.
With suspension of elective surgeries there is a potential morbidity and
mortality increase in LVAD candidates waiting for implantation.
Furthermore, there is a risk that the close connection between LVAD
patients and their treating centres becomes looser with increased
LVAD‐related complications and impaired well‐being. Patients undergoing
HT/LVAD evaluation experiencing delays in listing and/or surgery can
develop worsening nutritional, functional, or hemodynamic status. LVAD
supported patients with the indication of bridge to transplantation
might decline an offer to undergo heart transportation because of the
fear of being infected from the donor or because they fear they will not
get the optimal care from the overstressed healthcare system. Although
delay of these procedures may not immediately affect clinical outcomes,
there are important long-term and indirect implications for patients
with HF.
While it is important to prevent COVID‐19, the routine care should not
be discontinued to avoid severe complications both on clinical and
psychological sides. Therefore, specific LVAD management algorithms
should be implemented by every implanting and referring LVAD centre to
aim for early diagnosis and treatment of COVID‐19 or LVAD complications.
COVID-19 can create a prothrombotic environment in some patients
resulting in acute pulmonary embolism which may lead to acute right
ventricular failure. Early recognition of right ventricular dysfunction
and early intervention in patients who are hypotensive can be
lifesaving. The Impella RP is a temporary heart pump that provides right
ventricular circulatory support for patients who develop right side
ventricular failure or decompensation caused by COVID-19 complications,
including pulmonary embolus. For critically ill patients the Impella RP
can be rapidly deployed in a matter of minutes using a minimally
invasive technique in the cardiac catheterization laboratory or
operating room.
In LVAD patients with COVID-19 developing right ventricular (RV)
failure, medical management is the mainstay of therapy. Management
should be focused on volume management and optimization of RV preload,
reduction in RV afterload, improvement in the contractile state of the
right ventricle and optimization of cardiac rhythm.[32] Regulation
of the LVAD parameters is equally as important. Device speeds are chosen
to obtain satisfactory haemodynamic goals without inappropriate left
ventricular unloading, maintaining a rightward or neutral position of
the interventricular septum and limiting cardiac output while
maintaining an adequate mean arterial pressure. Vasodilatation or low
systemic perfusion pressures may result in inappropriate unloading of
the left ventricle and can contribute to leftward septal shift and
suction events which impair LVAD output and RV function and may
additionally trigger ventricular arrhythmias.
Serum lactate dehydrogenase (LDH) is a recognized biomarker for early
recognition of lung injury and assessment of severity in
COVID‐19.[18] In addition, a change in biomarker levels may be
useful in grading COVID‐19 severity in LVAD patients. Increase in LDH in
LVAD patients may raise specific concerns of haemolysis or LVAD
thrombosis and concomitant stroke. Infection, itself, acts as a trigger
for inflammatory response predisposing to pump thrombosis, ischaemic or
haemorrhagic stroke in LVAD patients.[33]
In patients with acute hypoxaemic respiratory failure due to COVID‐19,
prone ventilation may be effective in COVID‐19‐related severe ARDS
(improving lung mechanics and gas exchange). However, it may be
problematic in HF patients on LVAD support as prone positioning could
result in complications such as compression of outflow graft and
driveline, impaired venous return from increased thoracic pressure,
hardware malpositioning, and worsening right ventricular (RV)
haemodynamics. However, the probability of impaired functioning of the
LVAD by rotation or mechanical compression seems to be very low.