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 Doppler Patterns In Abdominal Vessels  Celiac Axis Scan transversely, look for “seagull” High systolic flow, some diastolic flow. Some spectral broadening Flow does not change after meals 29  Hepatic Artery Scan transversely, try porta hepatis or through ribs. Low resistance flow—lots of diastolic component Spectral Broadening is present Approx. 11% of hepatic arteries arise from the SMA Always check in heart transplant pts! Occlusion of the Hepatic Artery is a life- threatening complication!  Similar Image Pg. 185 Fig 8-76 B. Transverse Hepatic Artery Flow Pg. 198 31  Splenic Artery Most turbulent celiac branch—tortuous vessel Prone to aneurysm, especially in pts with chronic pancreatitis Always do Doppler exam of pancreatic pseudocysts, could be aneurysm instead. 32  Superior Mesenteric Artery Scan from sagittal plane Usually high resistance in fasting state After meal, becomes nonresistive with enhanced diastolic flow. Use Doppler of SMA to diagnose stenosis or occlusion of mesenteric vessels. 33  Similar Image Pg. 185 Fig. 8-76 D. Pg. 198 fig. 9-52 B. Sagittal SMA High resistance-fasting pt. with Low diastolic 34  Renal Artery The Main Renal Artery has low resistance pattern. Continuous flow provides constant perfusion to renal tissues. Spectral Broadening present Flow is dampened as get more peripheral into the kidney 35  Renal Artery Stenosis Very difficult to diagnose in native kidneys because can’t see entire vessel. -Renal Artery Occlusion can ONLY be diagnosed if entire vessel is examined. -Another problem is that pts with RA occlusion will quickly develop collaterals which may be mistaken for the renal artery. 36  Renal Artery Stenosis Also, at least 30% of patients have - multiple renal arteries. -If there is separation of the renal pelvis, DO NOT simply assume that it is hydronephrosis—USE DOPPLER—it may just be prominent renal vessels.  Renal Transplants In the main renal artery there is normally turbulence at the anastomosis (connection made at vessels from new kidney to transplant patient) -Only 12% of transplant pts develop RA stenosis (will see distal turbulence) -RA occlusion easier to diagnose because there is only one artery feeding the transplanted kidney. 38  Renal Transplant Rejection Normal transplants have low resistance flow. During rejection, resistance increases—have less and less diastolic flow. -May use Pulsatility Index or Resistive Index to quantify. RI of.7 or less=good perfusion RI of.7 to.9= possible rejection RI >.9=probable rejection 39 Doppler Patterns in Abdominal Vessels Renal Veins- - variable flow like IVC. -May be invaded by tumor or clot. -Always check in transplant patients 40 Doppler Patterns in Abdominal Vessels Normal Rt. Renal Vein flow Similar image Pg. 187 Fig. 8-79 8th Ed. Pg. 201 fig. 9-56 Rt. Renal Vein flow Flow above and below baseline like the IVC pattern 41 Doppler Patterns in Abdominal Vessels 7. Inferior Vena Cava- -Variable waveform. -Always check for tumor or clot. 42 Doppler Patterns in Abdominal Vessels 8. Hepatic Veins- -If normal have a variable pattern similar to IVC. Budd-Chiari Syndrome -thrombosis of hepatic veins. -rare disease-associated with: hematologic disorders,oral contraceptives,collagen disease,echinococcus,times just before/after pregnancy Sonographic Appearance-hepatic veins appear small/filled with echogenic 43  IVC Waveform Pg. 187 Fig. 8-81 A. Flow above and below baseline reflecting reflux of blood from Rt. Atrium during systole and variations 44 IVC/Hepatic Veins Pg. 179 Fig. 8-81 C. Complex waveform Above and below Baseline- reflux with Respiratio ns IVC/Hepatic Veins Pg. 179 Fig. 8-81 B. Triphasic flow of Hepatic veins with: Systolic (S), Diastolic (D) and atrial (a) components  Doppler Patterns in Abdominal Vessels 9. Portal Vein Toward Liver/Hepatopetal - -Relatively continuous flow at low velocities -Varies with respirations -With thromobosis—see thrombus in the PV, also, dilated SMV, Splenic Vein 47 Normal Portal Vein Flow Pg. 188 Fig. 8-82 Monophasic and Hepatopetal flow (toward the liver) 48  Doppler Patterns in Abdominal Vessels Cavernous Transformation of Portal Vein- -collaterals around the portal vein in patients with chronic PV obstruction. Diagnostic Criteria: 1.Extrahepatic PV not seen 2.Echogenic area at porta hepatis due to fibrosis 49 Cavernous Transformation (not in text)  Portal Hypertension -Usually result of intrinsic liver disease (cirrhosis or cancer, PV thrombosis) -Portal flow is hepatofugal-away from liver (Chronic) 51  Portal Hypertension Doppler Findings: -Low velocity in Portal Vein -Patent Umbilical Vein (ligamentum Teres) - (definitive diagnosis) -Flow varies from patient to patient -Loss of respiratory variation 52  Portal Hypertension 2-D Ultrasound Findings: -DilatedPortal, Splenic, Superior Mesenteric Veins -Patent Umbilical Vein -Varices (Collaterals) -Splenomegaly w/dilated vessels -Decreased Respiratory Response 53 Portal Hypertension Pg. 226 Gig. 9-38 A. Flow Revers al In Main Portal vein Portal Hypertension Pg. 226 Gig. 9-38 B. Flow Revers al In Main Portal Vein- Below the baselin e Spontane ous Shunting- venous collaterals Pg. 224  Spontaneous Shunting 1.Gastroesophageal: collaterals arise (varices) in the submucosa of the esophagus where the esophageal branches of the Left Gastric Vein form anastomoses with the hemiazygous and azygos veins. 57  Spontaneous Shunting 2. Paraumbilical Vein: looks like continuation of Left Portal Vein and extends down anterior abdominal wall to umbilicus. If not recannalized (patent) known as the Ligamentum Teres (pg. 209) Recanalized Umbilical Vein Pg. 226 Fig. 9-39  Spontaneous Shunting 3. Hemorrhoidal Anastomoses: Occur between the superior and middle hemorrhoidal veins. 60  Spontaneous Shunting Retroperitoneal Anastomoses: See small vessels around pancreas. Dilation of vessels may cause thickening of omentum- especially in children Use Doppler to distinguish from nodes These all occur in the body’s attempt to decompress portal hypertension.  Surgical Porto-Systemic Shunts 1. Portacaval- PV drains into IVC 2. Mesocaval- SMV drains into IVC 3. Splenorenal- Splenic Vein drains into Lt Renal vein 4. TIPS-Transjugular Intrahepatic Portosystemic shunt catheters are placed in the liver to drain from portal veins into hepatic veins Can verify patency of each of these with 62 Mesocaval Shunt Pg. 229 Fig. 9-41 TIPS Pg. 229 Fig. 9-42  Abdominal Aortic Aneurysm (AAA)- Aneurysm=a permanent localized dilation of an artery, with an increase in diameter of greater than 1.5 times its normal diameter 65  Abdominal Aortic Aneurysm (AAA)- Occurs in 5-7% of people over the age of 60 in the USA. People at High risk: Over age 60 Have Hypertension Smokers Have Vascular Disease (Coronary or Peripheral) Diagnosis often made by Dr. feeling pulsatile abdominal mass Abdominal Aortic Aneurysm- AAA Three predisposing factors: 1.Arteriosclerosis—most common 2.Syphilis 3.Trauma 67 Abdominal Aortic Aneurysm- AAA Clinical Symptoms: -may impinge on adjacent structures-- obstruction -may occlude a vessel and cause an embolism if it ruptures—intense back pain, drop in Hematocrit (45% of total blood volume, Red blood cells + White Blood Cells + Platlets) - 75% are asymptomatic *Ultrasound is method of choice to follow AAA’s Classification of Aneurysms 1. True Aneurysm 2. False Aneurysm(pseudoaneurysm)  True Aneurysms Lined by all 3 layers of the aorta Forms when the wall of the vessel gets weak Some occur secondary to underlying heart diseases  False Aneurysms (pseudoaneurysm) Not lined by all 3 layers of the Aorta A pulsatile hematoma that results from leakage of blood into the soft tissue abutting the punctured artery, with subsequent fibrous encapsulation and failure of the vessel wall to heal. Can occur after trauma by an accident or surgery or interventional cardiac catheterization or angiography procedure With color Doppler can see flow into protuberance during systole and out during diastole True v.s False Aneurysm Pg. 163 Fig. 8- 36 True False/pseudoaneurysm Descriptions of Aneurysms 1.Fusiform: most common presentation usually of the distal aorta at the bifurcation diffuse dilation of the vessel Elongated and tapering at both ends (spindle shaped) 73  Descriptions of Aneurysms 2. Saccular: larger than fusiform connected to the vessel lumen by a “mouth” or “stalk” may be partially or completely filled with thrombus can be very difficult to differentiate from a retroperitoneal mass or lymphadenopathy Descriptions of Aneurysms Pg. 163 Fig. 8- 37 75  Locations of Aortic Aneurysms 1.Infrarenal—located below the origin of the renal arteries (most common) 2.Perirenal—involves the level of the origin of the renal arteries— hard to repair 3.Suprarenal—located above the renal artery origins-may extend above diaphragm 76  Growth Patterns for Abdominal Aneurysms The normal aortic lumen diameter= Less than 3cm Ultrasound has a 98.8% accuracy rate for detecting aortic aneurysms (provided good technique is used)Therefore Ultrasound is the modality of choice for imaging. If the aneurysm is less than 6cm, it will have a very slow growth pattern, so the 77 patient is re-evaluated each year.  AAA Statistics * 75% of patients will survive for a year if the AAA is less than 6cm *50% of patients will survive for a year if the AAA greater than 6cm *25% of patients will survive for a year if the AAA greater than 7cm There is a 75% risk of fatal rupture if the AAA is greater than 7cm 78  AAA Statistics *1% of AAA (Less than )