ABD VESSEL DOPPLER FLOW PT 3

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Questions and Answers

What is the main reason for spontaneous shunting in the body?

To enhance blood flow to the heart

To decompress portal hypertension (correct)

To decrease the size of varices

To increase blood pressure

Which vein extends to the umbilicus and is known as the Ligamentum Teres when not recanalized?

Inferior Mesenteric Vein

Paraumbilical Vein (correct)

Superior Mesenteric Vein

Portal Vein

Which of the following describes the most common cause of Abdominal Aortic Aneurysm (AAA)?

Syphilis

Arteriosclerosis (correct)

Trauma

Congenital Defect

What clinical symptom is NOT commonly associated with an Abdominal Aortic Aneurysm (AAA)?

Constipation Signup and view all the answers

Which of the following is NOT a type of surgical portosystemic shunt?

Arterial Shunt Signup and view all the answers

What is the percentage of AAA occurrences in people over the age of 60 in the USA?

5-7% Signup and view all the answers

What method is preferred for following abdominal aortic aneurysms (AAA)?

Ultrasound Signup and view all the answers

Which of the following veins is involved in the hemorrhoidal anastomoses?

Superior and middle hemorrhoidal veins Signup and view all the answers

What characterizes a true aneurysm compared to a false aneurysm?

Lined by all three layers of the aorta Signup and view all the answers

Which of the following describes a fusiform aneurysm?

Most common presentation, elongated and spindle-shaped Signup and view all the answers

Which growth pattern is associated with abdominal aneurysms less than 6 cm in diameter?

Very slow growth pattern with annual evaluations Signup and view all the answers

What is a characteristic feature of a saccular aneurysm?

Connected to the vessel lumen by a mouth or stalk Signup and view all the answers

Where is the most common location for abdominal aortic aneurysms?

Infrarenal region, below renal artery origins Signup and view all the answers

Which of the following conditions can lead to the formation of a false aneurysm?

Trauma or surgical intervention Signup and view all the answers

What imaging modality is preferred for detecting aortic aneurysms?

Ultrasound Signup and view all the answers

What is the normal aortic lumen diameter considered for diagnostic purposes?

Less than 3 cm Signup and view all the answers

Study Notes

Spontaneous Shunting - Venous Collaterals

Venous collaterals form as a result of portal hypertension
These arise in specific locations:
- Gastroesophageal: Varices in esophagus, where esophageal branches of Left Gastric Vein connect with hemiazygous and azygos veins
- Paraumbilical Vein: Continuation of Left Portal Vein, extending down anterior abdominal wall to umbilicus. Absent recanalization (patent) is Ligamentum Teres (pg. 209)
- Hemorrhoidal Anastomoses: Between superior and middle hemorrhoidal veins
- Retroperitoneal Anastomoses: Small vessels around pancreas. Vessel dilation can cause omentum thickening, especially in children. Doppler is used for distinguishing from nodes. These all decompress portal hypertension.

Surgical Porto-Systemic Shunts

Portacaval: Portal Vein (PV) drains into Inferior Vena Cava (IVC)
Mesocaval: Superior Mesenteric Vein (SMV) drains into IVC
Splenorenal: Splenic Vein drains into Left Renal vein
TIPS: Transjugular Intrahepatic Portosystemic shunts: Specialized catheters placed in liver to drain portal veins into hepatic veins. Patency (openness) is verified.

Abdominal Aortic Aneurysm (AAA)

AAA: permanent dilation of abdominal aorta. Diameter >1.5x normal diameter
Risk Factors:
- Age over 60
- Hypertension
- Smokers
- Pre-existing vascular disease (coronary or peripheral)
Diagnosis: Detection of a pulsatile abdominal mass.
Predisposing factors:
- Arteriosclerosis (most common)
- Syphilis
- Trauma
Clinical Symptoms:
- Impingement on adjacent structures (obstruction)
- Vessel occlusion (embolism)
- Rupture presents with intense back pain, and reduction in hematocrit (45% of total blood volume). 75% of AAA patients are asymptomatic. Ultrasound is used in monitoring.
Classification:
- True Aneurysm: Lined by all 3 layers of the aorta. Develops from a weakened arterial wall. Secondary to underlying heart diseases.
- False Aneurysm (Pseudoaneurysm): Not lined by all three layers. Results from blood leakage into surrounding tissue. Associated with trauma, surgery, or catheterization. A pulsatile, fibrous-covered hematoma exists. Color Doppler is used to detect blood flow in the protuberance during systole and outflow during diastole.
Descriptions of Aneurysms:
- Fusiform: Most common. Diffuse dilation of vessel usually on the distal aorta at the bifurcation. Elongated and tapers at both ends (spindle-shaped)
- Saccular: Larger than fusiform. Connected to the vessel lumen by a "mouth" or "stalk". Often filled with thrombus (blood clot). Difficult to distinguish from retroperitoneal masses of lymphadenopathy.
Locations:
- Infrarenal: Below renal arteries (most common)
- Perirenal: Involves the level of renal arteries origins. Difficult to repair.
- Suprarenal: Above renal artery origins. Can extend above diaphragm.
Growth Patterns: Normal aortic diameter is <3cm. Ultrasound 98.8% accurate. For AAA <6cm, patient monitoring is annually.
AAA Statistics:
- 75% survival for a year if <6cm.
- 50% survival for a year if >6cm.
- 25% survival for a year if >7cm.
- Rupture risk is 75% for >7cm.
- 1% rupture rate for <5cm.
- 5% mortality during repair if asymptomatic rupture is addressed before it happens. - 50% mortality during emergency repair if rupture happens.
Ultrasound Findings:
- Evaluate entire abdominal aorta (diaphragm to common iliac arteries)
- Measure the proximal, mid, distal Aorta. Right and Left Common Iliac Arteries.
- Normal aortic measure is <3cm. Tapers distally. Aorta with non-tapering distal region is aortic ectasia.
Aneurysm Thrombus: Presence of aneurysm requires evaluation for thrombus. Old thrombus presents as medium to low-level gray echoes due to calcifications. Beware of artifacts.
Aortic Aneurysm extending above diaphragm: Difficult to image.
Transverse Abdominal Aortic Aneurysm: Measurements are taken.
Abdominal Aortic Rupture: Sites of rupture typically occur laterally below Renal vessels. May cause hemorrhage into pararenal or perirenal spaces. Displaces kidneys and obliterates psoas muscles, or displaces vessels.
Rupture Complications: Large AAAs can compress adjacent structures like CBD (obstruction). Renal artery problems causing hypertension and ischemia. Aneurysm with Retroperitoneal fibrosis can cause ureter problems.
Aortic Graft: Abdominal aortic aneurysms are repaired with Dacron graft material. Grafts are very echogenic, and aneurysms may swell or develop pseudoaneurysms (a vascular, fluctuant mass) after graft surgery, due to leaks.
Aorta Graft Techniques: Early graft placement is localized to aorta, bifurcation or in femoral artery. Advancements allowed graft placement into renal arteries.
A Endovascular Graft Complications: Endoleaks can occur immediately after placement. Leak type, technique, and aorta affect this complication rate.
Other Pulsatile Masses:
- Lymphadenopathy: Pulses with aorta. Usually a result of Lymphoma. Retroperitoneal nodes are most common cause of pulsatile abdominal mass in ultrasound.
- Pancreatic Tumors: hypoechoic; displaces pancreas. - Retroperitoneal Sarcomas: Rare malignant tumor, same space as lymphadenopathy. Echogenicity varies with tissue composition (Fatty more echogenic than Fibrous or myomatous).
Aortic Dissection: Separation of aortic wall layers with blood flowing through a "false lumen". Typical symptoms are known aneurysm, sudden excruciating chest pain, radiated to back, and patients are usually 40-60, usually males, with hypertension. Possible causes include tearing of intimal layer of the tunica intima for ascending aorta dissections. Tearing occurs in the tunica media for ruptures in other locations. Separation can circle the entire circumference of aorta or occur in limited segment of wall, with potential for body cavity rupture. 3 types of aortic dissection exist.
- Type I: Starts at aortic root, stretches entire aortic arch, high risk of cutting off artery supply to arteries.
- Type II: Begins at or below subclavian artery origin, may extend to abdominal aorta or not. Associated with Marfan's Syndrome. - Type III: Starts at lower descending aorta, extends into abdominal aorta. Risk of artery supply being cut to renal arteries.
Causes of Dissection: Cystic Medial Necrosis weakens arterial wall. Marfan's Syndrome; a genetic disorder causes progressive stretching of arteries. Hypertension.
Rupture of Aortic Aneurysm: Signs: Excruciating pain (especially abdominal), shock, and expanding abdominal mass. 40-60% mortality during operation for rupture. Sites of rupture are infrarenal or suprarenal regions (lateral wall, below renal vessels). May cause hemorrhage into pararenal space with displacement of kidneys, obliteration of psoas muscle. Hemorrhage can occur in perirenal spaces, displacing vessels at the renal hilum and compressing aortic walls together. Large ruptures can compress adjacent structures like CBD or renal artery.

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Description

This quiz covers the formation of venous collaterals due to portal hypertension and various surgical porto-systemic shunts. Learn about the specific locations of collaterals and the types of shunts such as portacaval, mesocaval, and TIPS. Test your knowledge on this crucial aspect of vascular surgery and its implications on portal hypertension.