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 radius of the outflow tube is 1 cm and the LVAD pump generates a pressure of 45 mm Hg, what is the velocity of blood through the outflow tube if peripheral resistance is 1 mm Hg⋅s⋅mL⁻¹?

A) 45/π cm/s
B) 45/π cm³/s
C) 45 cm/s
D) 45 cm³/s

Correct Answer:

Verified

Unlock this answer now
Get Access to more Verified Answers free of charge

Access For Free