Passage In the Event of End-Stage Heart Failure, a Left Ventricular

Passage
In the event of end-stage heart failure, a left ventricular assist device (LVAD) can be used as a heart transplant bridge to keep a patient alive.  The first iterations of LVADs were pulsatile and mimicked the physiological pumping action of the heart (Figure 1) .
Figure 1  A pulsatile-flow LVAD schematicA pulsatile-flow LVAD assists ventricular systole by mechanically pumping blood from a weakened left ventricle into the aorta through a pair of one-way valves.  The pressure differential ΔP generated by the pump is related to cardiac output (CO) and vascular resistance (VR) :ΔP = CO × VREquation 1The efficiency and performance of the heart (or LVAD) can be determined by the patient's cardiac pressure-volume (PV) loop.  A cardiac PV loop plots the pressure and volume of the blood in the left ventricle throughout a single cardiac cycle (Figure 2) .
Figure 2  Cardiac PV Loop of a pulsatile-flow LVADBlood pressure is often represented by only two numbers:  arterial systolic and diastolic pressures.  A more detailed representation of blood pressures is shown in a blood pressure profile, which graphs the blood pressure throughout the length of the different vessel groups (Figure 3) .  Multiple pressure fluctuations are shown within a vessel because the pressure is traced across multiple cardiac cycles.
Figure 3  Blood pressure profile of the different vessels
-If the pulsatile-flow LVAD in Figure 2 pumps with a frequency of 1.5 Hz, what is the volumetric flow rate of blood throughout the systemic circulatory system?

A) 2,800 mL/min
B) 6,300 mL/min
C) 9,900 mL/min
D) 10,800 mL/min

Correct Answer:

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