6
Diagnosis
Cardiovascular Problems
Î Continuous-flow devices account for the majority of durable LVADs
implanted today. Most early generations of LVADs had pulsatile
pumps. Intracorporeal pulsatile devices are no longer available
commercially, but paracorporeal (the pump sits outside of the
patient's body) pulsatile devices are still in use (Figure 3).
Î The two most common causes of pump failure are disconnection of the
power and failure of the driveline.
Î There is a risk of de novo thrombus formation within the pump, which
can cause hemolysis and a drop in flow.
• Patients with MCS are usually anticoagulated with antiplatelet agents
and warfarin, but there is still an increased risk of pump thrombosis,
thromboembolism, and stroke despite therapeutic anticoagulation.
Î Additional causes of poor pump flow are RV dysfunction, suboptimal
pump orientation, or compromise of the inflow/outflow cannula.
Î Preexisting RV dysfunction is common before LVAD implantation
because of the effect of the primary cardiomyopathy, pulmonary
hypertension, or both.
Î Although significant new ischemic events or pulmonary emboli are
rare in patients with an LVAD, tachyarrhythmias are common.
Non-Cardiovascular Problems
Î The most common adverse events during long-term mechanical support
are infection (particularly in the driveline), bleeding, and stroke.
Î It is important to understand the difference between blood flow and
perfusion when assessing any patient with suspected cardiovascular
hemodynamic instability, especially patients with an LVAD, in whom
the peripheral arterial pulse is not a reliable indicator.
• In patients without an LVAD, an MAP >60 mm Hg will usually still provide
adequate tissue perfusion.
• In the noninvasive assessment of the BP of a patient with a continuous- flow
LVAD, use of a manual BP cuff and a Doppler is the recommended approach, with
NIBP as a secondary option because of the limitations of NIBP assessment in this
population.
• Clinical findings such as skin color and capillary refill are reasonable predictors
of the presence of adequate flow and perfusion, especially in MCS-supported
pulseless patients.
