Cardiac Assist Devices Flashcards
ECMO
pt being put on bypass that is not having cardiac surgery
is the heart arresting and cross clamp placed during ECMO?
no
what is the purpose of ECMO
keep pt alive during ACUTE cardiac or respiratory failure
venovenous (VV) ECMO
drawn from right side of heart
oxygenated by ECMO
returned to right side of heart
when is VV ECMO indicated?
respiratory failure
can you use VV ECMO for a pt with cardiac failure
no
cannula for venovenous ECMO
outer lumen for drain blood to ECMO
inner lumen infuses blood back into RA
Venoarterial (VA) ECMO
blood removed from right heart
oxygenated by ECMO
returned to left side of heart via arterial cannula
when is VA ECMO indicated?
cardiac and respiratory failure
what is the advantage of VA ECMO compared to VV ECMO
VA can be used in cardiac failure
oxygenation improved pulm vasculature and decrease pulm HTN then heart failure resolves
disadvantage to VA ECMO (compared to VV ECMO) 3
1- non pulsatile perfusion
2- potentially less oxygen to coronary arteries
3- higher chance of emboli entering arterial circulation
why is there potentially less oxygen to coronary arteries in VA ECMO?
because oxygen supply is better when it enters from the heart rather than machine
Ventricular Assist Device (VAD)
artificial heart placed in pt with heart failure to help ventricle pump
how does VAD work? 3
1 tubing placed inside ventricle
2- tubing withdraws some blood into a pump
3- pumps back into body through reinfusion tube
how does VAD increase CO?
helps heart pump
improves hearts own ability to pump by relieving fluid overload
what are VAD meant to be a bridge for?
heart transplant, they have risk of clotting and stroke
what are the three types of VADs?
1-long term intracorporeal VAD
(pump and tubing in body)
2- short term intracorporeal VAD (catheter)
3- short term extracorporeal VAD (tubing inside with pump outside)
long term intracorporeal VAD
long term use in pt with permanent HF
insertion with open heart surg and bypass
internal catheter VAD other name
impella cardiac assist device
how does internal catheter VAD work?
small pump in LV that removes blood from LV and pumps to aorta
extracorporeal VAD other name
tandem heart
when is tandem heart indicated
acute HF when weakened from recent heart surgery
extracorporeal VAD how does it work
venous catheter inserted in femoral vein into RA then LA
draws oxygenated blood out to VAD
pumps back in via arterial cannula in femoral artery
anesthetic implications for pt with VAD undergoing non cardiac surgery (6)
a line required MAP used to trend BP usually on anticoagulants RSI indicated Electromagnetic interference can alter function more susceptible to infection chest compression controversial
why do we need an aline for people with VADs?
flow is nonpulsatile thus NIBP are inaccurate
what should the MAP be at for people with VAD?
60mmHg
why are VAD pts usually on anticoagulants
pumps cause hemolysis and thrombolytic events
what causes electromagnetic interference?
bipolar cautery is preferred
if monopolar must be used then place grounding pad away from VAD
why are chest compressions controversial in VAD pts
can dislodge cannulas and lead to immediate death
OR will die without compressions
4 anesthetic considerations for pt with VAD
identify and talk to VAD team
secure a power source for VAD
establish safe coagulation plan with surgeon and cardiologist
hemodynamic stability crucial
what is the VAD team composed of?
cardiac surgeons, nurses, perfusionists etc
What information do you need from the VAD team?
pump speed and flow
rpm and L/min
How long do VAD batteries last?
6 hr
what is included in coagulation plan for VAD pts?
get coagulation labs (PT, PTT, INR)
pts on warfarin should switch to heparin before elective surgery
what two things do you need to be cautious of VAD patients with hemodynamic stability?
maintain preload (pump flow decrease when preload decrease) avoid hypertension (decreases output of device when afterload is increased) **blood can pool in heart and cause thrombi**
intra aortic balloon pump
balloon inserted into aorta via femoral artery
attached to console that triggers inflation and deflation
when does the IABP balloon inflate?
dichrotic notch of aline or t wave of ECG
when does the IABP balloon deflate
at or prior to R wave
what things can trigger balloon inflation?
ECG
aline waveform
pacemaker
benefit of balloon inflation
diastole,
increases diastolic pressure
increases Coronary perfusion pressure
benefit of ballon deflation
systole
sucks blood forward
decrease afterload and oxygen demand
increases CO
how much can a IABP increase CO by?
40%
when is IABP indicated?
cardiogenic shock
acute heart attack
difficulty weaning off bypass
c pulse heart pump
extra aortic balloon pump
“permanent”
epicardial sensing leads attached to LV
benefits of C pulse heart pump
placed thoracotomy (not sternotomy) no anticoagulants bc external to vasculature
when does the balloon inflate c pulse pump? benefit?
diastole
increase coronary blood flow
increases CO (second pulse)
when does the balloon deflate c pulse pump? benefit?
prior to systole (detection of R wave)
decrease afterload
increases CO
