System and method to simulate hemodynamics
A system for hemodynamic simulation comprises a vessel having properties of a blood vessel, a reservoir containing a quantity of fluid, tubing connecting the vessel and reservoir, and at least one pump for circulating the fluid within the system. Fluid can be tissue culture medium or blood analog fluid, and the vessel may include mammalian cells attached to its inside. A drive system, comprising two reciprocating drive shafts that are coupled by a cam, enables the uncoupling of pulsatile flow and pulsatile pressure to provide independent control over wall shear stress and circumferential strain. The shaft drives two pumps that are 180 degrees out-of-phase and are connected upstream and downstream of the vessel, and effect this uncoupling.
1 . A system configured to produce biomechanical conditions, comprising
a specimen unit configured to hold a specimen;
a pump system coupled to the specimen unit and configured to generate pressure and flow conditions in the specimen unit;
a drive system coupled to said pump system; and
wherein said drive system is configured to control said pump system to independently control each of pulsatile fluid flow and pulsatile pressure waveform biomechanical conditions at the specimen unit.
2 . The system of claim 1 , wherein the pulsatile fluid flow and the pulsatile pressure waveform are generated to control phase, wherein a phase variation is between 0 to 180 degrees.
3 . The system of claim 2 , wherein the phase variation is greater than 100 degrees.
4 . The system of claim 3 , wherein the pulsatile fluid flow, the pulsatile pressure magnitude and phase hemodynamic conditions are selectively controlled to determine shear stress or circumferential strain at the specimen unit.
5 . The system of claim 1 , wherein a predetermined set of hemodynamic conditions are controlled to within a prescribed percentage over a length L and radius r at the specimen unit.
6 . The system of claim 1 , further comprising at least one specimen arranged in said pressure and flow conditions in the specimen unit.
7 . The system of claim 6 , wherein said specimen comprises a plurality of specimens arranged in parallel or in series, and wherein said specimen comprises a graft.
8 . The system of claim 6 , wherein said specimen is an excised vessel before bypass implantation.
9 . The system of claim 1 , wherein a plurality of pumps in the pump system are selectively operated out of phase with each other.
10 . The system of claim 1 , wherein said pump system comprises at least one of a first pump subsystem, a second pump subsystem or a third pump subsystem, wherein said first pump subsystem is configured to control input frequency and amplitude of an oscillatory flow at the specimen unit, wherein said second pump subsystem is configured to control output frequency and amplitude of an oscillatory flow at the specimen unit, and wherein said third pump subsystem is configured to control an external pressure waveform at the specimen unit.
11 . The system of claim 1 , wherein the pump system comprises:
a steady state pump subsystem configured to control a volume and speed of a steady state flow of the flow loop; and
at least one member selected from the group of
a first pump subsystem configured to control an input pressure pulse and input flow of the input pressure pulse upstream of the specimen unit,
a second pump subsystem configured to control an output pressure pulse and output flow of the input pressure pulse downstream of the specimen unit, and
a third pump subsystem configured to control an external pressure/flow at the specimen unit.
12 . The system of claim 1 , wherein the biomechanical conditions comprise reproducing three-dimensional hemodynamic conditions.
13 . A method for producing hemodynamic conditions, comprising:
providing a chamber for producing hemodynamic conditions therein;
providing a pump system for generating pressure and flow conditions in the chamber;
controlling said pump system to independently control each of pulsatile fluid flow and pulsatile pressure waveform hemodynamic conditions in the chamber.
14 . The method of claim 13 , wherein the hemodynamic conditions produce three-dimensional hemodynamic conditions.
15 . The method of claim 13 , wherein the pulsatile fluid flow and the pulsatile pressure waveform are generated to control phase, wherein a phase variation is greater than 100 degrees.
16 . The method of claim 15 , wherein the pulsatile fluid flow, the pulsatile pressure waveform and phase hemodynamic conditions are selectively controlled to determine shear stress or circumferential strain at the specimen unit.
17 . The method of claim 14 , wherein providing the pump system comprises:
providing a steady state pump configured to control a volume and speed of a steady state flow of the flow loop; and
providing at least one of a first pump configured to control an input pressure pulse waveform and input flow of an input pressure pulse upstream of the chamber, a second pump configured to control an output pressure pulse waveform and output flow of an output pressure pulse downstream of the chamber or a third pump configured to control an external pressure/flow at the chamber.
18 . The method of claim 14 , wherein said controlling said pump system comprises controlling input frequency and amplitude of an oscillatory flow at the chamber, output frequency and amplitude of an oscillatory flow at the chamber and an amplitude of a constant flow at the chamber.
19 . The method of claim 14 , further comprising providing at least one specimen arranged in said hemodynamic conditions in the chamber, wherein said specimen is an excised vessel before bypass implantation.
20 . A system configured to produce hemodynamic conditions, comprising
a specimen unit configured to hold a specimen;
a pump system coupled to the specimen unit and configured to generate pressure and flow conditions in the specimen unit; and
a drive system unit coupled to said pump system;
wherein said drive system unit is configured to control the pump system to independently control fluid flow, pressure and diameter variation hemodynamic conditions for the specimen unit.
21 . A system configured to produce hemodynamic conditions, comprising:
a specimen unit configured to hold a specimen;
a pump system coupled to the specimen unit and configured to generate pressure and flow conditions in the specimen unit; and
a drive system unit coupled to said pump system;
wherein said drive system unit is configured to control the pump system to independently control each of magnitude and phase of wall shear stress (WSS) and magnitude and phase of pulsatile circumferential strain (CS) to create a range of stress phase angle (SPA).