Abdominal Vessel Doppler Flow Patterns PDF

Abdominal Vessel Doppler Flow Patterns Abdominal Vascular Pathologies  Doppler Technique Sample volume “gate” is placed in the vessel and adjusted to encompass, but not exceed the diameter Angle of gate must should be 60 degrees or less in order to be accurate(adjusted...

Abdominal Vessel Doppler Flow Patterns Abdominal Vascular Pathologies  Doppler Technique Sample volume “gate” is placed in the vessel and adjusted to encompass, but not exceed the diameter Angle of gate must should be 60 degrees or less in order to be accurate(adjusted by angle knob on the control panel) Patient may need to suspend respirations while some vessels are or above the baseline= Flow toward the transducer Sample Volume “Gate”  Abdominal Doppler Techniques Doppler commonly used to detect: The presence or absence of blood flow The direction of blood flow Flow Disturbance Patterns Also has been used for: Tissue Characterization Waveform Analysis 4  Presence/Absence of Flow Doppler frequently used to distinguish vascular structures from nonvascular structures. (for example: the CBD from the Hepatic Artery) 5  Direction of Flow Can detect reversal of flow Used to distinguish arteries from veins (for example: in portal hypertension,the blood in the portal vein may be hepatofugal (away from the liver) instead of hepatopedal (toward the liver = Normal) Hepato-Petal- used more often  Disturbance of Flow Flow will be faster with a disturbance (post stenosis) Swirls and eddies-not smooth. (turbulent flow, chaotic, eddy currents, moving in different directions) May be due to stenosis of a vessel or dilation of an aneurysm.  Tissue Characterization Area of Research Doppler is thought to be capable of characterizing tissue because of specific perfusion patterns characteristic of some tissues or states of tissue activity. 8  Tissue Characterization- Examples Hepatocellular Carcinomas (Liver Ca): appear to have specific Doppler pattern. Peripancreatic Artery Pseudoaneurysms have turbulent flow patterns. Pancreatic Tumors may have specific flow pattern  Doppler Waveform Analysis The shape of spectral waveform provides information about the vascular impedance of the organ the vessel supplies (How much pressure/effort is required to get the blood into the organ) Spectral Analysis tells the velocity (speed + direction)and turbulence of the blood flow. 10  Nonresistive/Low Resistance Waveform A Lot of diastolic flow Supply Organs that need CONSTANT PERFUSION Examples: Internal Carotid Artery, Hepatic Artery 11 Resistive/High Resistance Waveform Very little diastolic flow May even have reverse flow during diastole Supply organs that DO NOT need constant perfusion Ex: External Carotid Artery, Brachial Artery Text 7th Ed. Similar image Pg. 185 Pg. 198 Fig. 8-76 A. & D. Fig. 9-52 Low Resistance (increased diastolic flow) (Hepatic Artery) High Resistance (Low diastolic flow) (SMA) 13 Flow patterns/resistance in Celiac vs SMA vs Aorta Pg. 185 Fig. 8-76 D.  Quantifying Resistance Resistive Index: ratio that compares peak systole velocity to minimum diastole velocity. (Peak Systolic – Min Diastolic) RI= Peak Systolic Velocity *Less than 0.7 = Normal 15  Spectral Display x axis= Time (horizontal axis) Y axis= Doppler Shift Frequency (velocity) (vertical axis) z = Quantity of blood flowing at a given velocity (gray scale-more blood =brighter signal) 16 Y Pg. 20 Fig. 1-29 X Spectral Display Plug Flow /laminar: Clear “window” in spectral waveform—Most of the blood cells are traveling at about the same velocity across the vessel. (smooth) Opposite of Spectral Broadening Fill-in of the spectral window is caused by friction between the cells and the arterial walls/stenotic areas Spectral Wave- Form with a “Clean Window ” Below the trace Spectral Broadening Pg. 19 Fig. 1-26 Abdominal Doppler Techniques Doppler often performed on routine abdominal sonograms Have patient hold his/her breath to get best Doppler Info- Set Doppler Sample Volume (gate) to cover vessel width, but NOT larger than the vessel. If the sample volume is too large, noise and “ghost” echoes may appear from surrounding vessels and structures. 23 Abdominal Doppler Techniques Aliasing- A Doppler artifact seen with high frequencies where the peak of the wave form “wraps” around and appears below the baseline To correct the issue change to a lower frequency transducer or switch to Continuous Wave Doppler if possible. Aliasing Pg. 130-131 Fig. 7- Abdominal Doppler Techniques Angle of Doppler beam to blood flow MUST be less than 60 degrees! If angle is more than 60 degrees, the velocity calculations will be inaccurate. Top of color Map = Toward the Transducer Bottom of Color Map = Away from Transducer Abdominal Doppler Techniques Blue Red Pg. 21 Fig. 1-32 Top of color Map = Toward the Transducer Bottom of Color Map = Away from Transducer