Hemodynamics: Ch 17 Flashcards
what is flow? steady flow?
movement of a fluid from one location to another; fluid moving at a constant speed or velocity
how does blood move in pulsatile & phasic flows?
variable velocity
what are 4 descriptions of pulsatile flow?
arterial, cardiac contraction, high rate, higher pressure
4 descriptions of phasic flow?
venous, respiration, low rate, lower pressure
how would you describe flow? velocity?
how much vol, vol/time; how fast, distance/time
one single blood cell travelling rapidly is described as what?
high velocity, low flow
what is laminar flow? what are the 2 types? describe each
flow streamlines are layered, aligned, parallel.
1. plug flow - small regions, similar velocities (narrow doppler spectra)
2. parabolic flow - layers have individual speeds, highest in the center slower at vessel wall. (concentric rings of flow)
what is turbulent flow? what is it associated with?
chaotic flow in many directions and speeds, no streamlines; cardiovascular pathology and increased velocities (stenoses);
in turbulent flow when the flow energy is lost what is it converted to? what is turbulence aka?
sound (murmurs bruits) or vibration (thrill); doppler spectral broadening
what is a vortex? eddy currents?
swirling pattern of rotational flow; turbulent flow
what is reynold’s number? what are the values?
a unitless number indicating whether flow is laminar or turbulent. less than 1500 = laminar, more than 2,000 = turbulent
what on the machine can mimic turbulence even with normal flow?
doppler gain settings
what is Bernoulli’s principle? how is this seen in stenosis?
describes relationship bw pressure (potential energy) and flow (kinetic energy); more kinetic en less potential en in stenosis.
