Perioperative Mx of pts with ventricular assist devices undergoing non-cardiac surgery blue book article Flashcards
What are ventricular assist devices?
Mechanical circulatory support devices giving temporary or long-term support for pts with advanced heart failure non-responsive to maximal medical therapy.
They can support the LV, RV or both.
What is funding for VADs approved for?
as a bridge to heart transplantation
What’s the periop M&M with pts with VADs undergoing non-cardiac surgery or pregnancy?
low in the immediate periop period & @ 12/12 follow-up
What’s the physiological goal of a VAD?
reduce LV work & provide adequate systemic perfusion by active unloading of the LV & returning blood to the aorta under +ve pressure
blood is drained from the LV apex via an inflow cannula & returned to the ascending aorta via an outflow cannula
What are the 3 devices used for VAD support in ANZ? type of continuous flow pump? pump speed? where implanted? anticoagulation targets (warfarin)?
Heartmate II- axial pump- 9000rpm- subdiaphragmatically implanted- INR 2.5-3.5
Heartmate III- magnetically driven centrifugal pump- 5000-6000rpm- implanted within the pericardium- INR 2-3
HeartWare HVAD- magnetically driven centrifugal pump- 2500rpm- implanted within the pericardium- INR 2-3
all use continuous flow pumps
While it’s not an approved indication in ANZ, what’s the most common indication for VAD implantation worldwide?
destination therapy- in pts with advanced HF ineligible for heart transplant
What proportion of pts with VADs have unplanned hospitalisation within the first 6/12 of device placement? main reasons?
30%
bleeding
infection (esp driveline)
stroke or device thrombosis (pts require strict anticoagulation regimen)
RHF
What are the most common non-cardiac procedures for pts with VADs?
UGI endoscopy (incr risk GI bleeding as these pts need anticoagulation)
Should cardiac anaesthetists be involved in the care of pts with VADs presenting for non-cardiac surgery?
yes if major surgery, the pt has multiple comorbidities or is on long-term pharmacological support
They should be managed at cardiac centres with experience in VADs, though
What’s the most notable periop issue for pts with VADs? others?
hypotension
AKI
excess bleeding
arrhythmias
What should occur for periop Ax/planning of pts undergoing elective surgery with VADs?
Multi-D Ax by anaesthetist, procedurals, HF cardiologist, VAD nurse specialist or perfusionist
May require consultation with card surg or haematologist
Ax:
functional status
organ function (renal, hepatic, haematological, obtain ECG & CXR, up-to-date echo for all but the most minor procedures & particularly focus on RV function which is often impaired)- correct any reversible issues eg. electrolytes, hypotension
meds
function of the VAD
function of any ICD or pacemaker
Planning:
anticipate greater than usual blood loss & blood typed & X-matched for transfusion
Monitoring:
-IABP for all but the most minor procedures (use US guidance given non-pulsatile arterial flow)
-Large-bore IV as bleeding risk
-Non-invasive BP monitoring (eg. intermittent MAP via doppler US)
-pulse ox trace quality poor due to non-pulsatile flow but can still get readings
-NIRS (near infra-red cerebral spectroscopy) is useful, doesn’t rely on pulsatile flow
-BIS useful since haemodynamic responses to nociception/awareness may be absent or blunted
-place external defibrillator pads prior to induction
-consider CVC if large fluid shifts or inotrope requirement anticipated
-intra-op TOE useful for most cases
-cardiac surgeon should be immediately available for procedures occurring in close proximity to a VAD
-VAD specialist present, interrogate device prior to OT & be present throughout- should advise anaesthetist & procedurals particularly if reduced VAD flow (L/min) for a given pump speed (rpm)
-on transfer to OT, VAD uses it’s battery power (battery life 6-10 hrs); once pt positioned, connect to UPS
-spare batteries should remain with pt throughout the case
-pacemaker tech- common in pts with VAD. program to asynchronous mode immediately prior to any surgery & antitacchycardia & defibrillator functions disabled
-post-op likely extubated but then to ICU, if minor procedure CCU may be appropriate
optimise intravascular volume, prevent hypox/hypercapnia (PVR), avoid nosocomial sepsis, adequate analgesia to limit SNS stimulation.
urgently assess any change in VAD functioning with echo.
keep pt connected to external defibrillator until any ICD or pacemaker is reprogrammed.
recommencement of anticoagulant & anti platelets is a multi-D discussion- no evidence incr thromboembolic risk if bridging heparin omitted yet no incr rate of periop bleeding or transfusion if use heparin- once acute bleeding risk passed, use UFH to bridge until INR >2.
What factors confound physical examination of pts with VADs?
arterial pulses typically non-palpable
NIBP requires portable continuous wave Doppler device
device hum obscures any HS & murmurs
Along with anticoagulation with warfarin, what else are pts with VADs on?
antiplatelet- aspirin or if aspirin resistance, clopidogrel added
What’s the anticoagulation plan for pts with VAD undergoing surgery?
elective: withhold warfarin for 5 days, bridge with UFH infusion once INR <2.0
emergency: reverse to INR <1.5 depending on procedure & pts thrombotic risk- should use a factor concentrate NOT vitamin K, given the pt will require warfarin reintroduction early postop
Why are major regional & neuraxial techniques typically avoided in pts with VADs?
risks ass’d with anticoagulation & higher incidence of hepatic dysfunction
