Ventricular Assist Device Flashcards
What is a VAD?
A ventricular assist device. Used to partially or fully replace the function of a failing ventricle. (It’s basically a pump).
At what stage of heart disease would a VAD be required?
Refractory reactions requiring special intervention (stage D, near the end)
How are VAD’s used in the context of a patient’s condition?
Bridge to recovery (VAD used to assist heart function until it recovers)
Bridge to transplantation (VAD used to keep heart failure patient alive until heart transplant available)
Destination therapy (VAD used to support patient ineligible for heart transplant for the rest of their lives)
Describe the mechanical properties of contemporary VAD’s.
They are continuous flow pumps. Centrifugal pumps or axial flow impeller driven pumps.
Side effect: no pulse or significantly lowered pulse intensity.
What is the main difference between first and second generation VADs?
First generation = pulsatile
Second generation = non-pulsatile, impeller (think propeller) driven
What were the significant findings of the REMATCH trials (1998-2001)?
Survival rate for end-stage heart failure patients was 23% with VADs as compared to 8% with optimal medical management.
Two major complications of VADs = mechanical failure and infection.
LVAD group also had improved metabolic and clinical function at time of transplant + significantly less incidence of renal failure and right heart failure
What is a tandem heart pVAD (percutaneous/outside ventricular assists device)? Goals of its use?
Extracorporeal centrifugal pump, capable of delivering up to 5 L/min; assists in the operation of both ventricles
Assist LV function, decrease myocardial O2 demand, increased CO and MAP.
Pre-operatively, what should you find out about a patient on VAD?
> Is it 1st or 2nd/3rd gen? (pulsatile or not?)
> Anti-coagulation status (LVAD pts are usually on anti-coag therapy with warfarin; need to convert to IV heparin)
> Flow rate of pump?
> Will there be interference from electrocautery (where is the surgical site?)?
Where should you connect the LVAD once the patient enters the OR?
Connect it to the main power supply.
You notice low LVAD output with progressive increase in CVP. What could be happening and what should you do?
These symptoms suggest right ventricular dysfunction. Assess and determine whether you need to administer positive inodilators or pulmonary vasodilators.
What are anesthetic considerations when managing patients with VADs?
The VADs do not follow Starlings law with respect to stroke volume so can pump the volume delivered to it – therefore, inadequate prefilling = inadequate flow ; too much afterload = too much back up and therefore inadequate flow (Risk of thrombosis).
Invasive monitoring should be used (central venous or pulmonary artery catheter, or TEE) for procedures in which great changes in intravascular volume is anticipated.
Attenuate/minimize sympathetic response during laryngoscopy and take particular care to avoid hypertension.
Factors that increase PVR and decrease RV function can limit LVAD flow.
