LVADS

Question 1

after load sensitivity of cf LvAD

Answer 1

CF LVAD flow highly sensitive to after load. therefore need a narrow range of pressures

Question 2

HEAD CURVE

of axial vs rotary LVAD

Answer 2

Pump head pressure (dP across the pump) vs flow.
Centrifugal pumps have a flat head curve — operate over a wide range of flow for a small dP.
- results in some pulsatility

Question 3

Effect of flat head curve on low flow conditions

Answer 3

steeper head curve of axial pumps responds to an increase in SVR by increasing the pressure generated across the pump, limiting the decrease in flow by increasing outlet pressure.

At low-flow conditions, this retains the capability to enforce high blood pressures with adequate LV volume.

** However, it also results in high inlet suction that in a low LV volume state can potentiate arrhythmias, create suction events, or lead to hemolysis.

Question 4

formula for PI for HM 2

Answer 4

he formula for calculating a PI for the HeartMate II (PIHM II) [(flowmax – flowmin)/flowavg] 10.