Vascular Shunts

Question 1

T/F: A portosystemic shunt is a good example of an arterio-venous malformation.

Answer 1

False, portosystemic shunts are abnormal communications between 2 venous systems [venovenous shunts].

Question 2

Arteriovenous malformations lead to ________ ________.

Answer 2

Tissue hypoxia [this is because most arterial blood is bypassing the capillary bed and going directly into the draining vein.]

Question 3

The most common site for an AV fistula is the ______.

Answer 3

Liver

Question 4

These types of shunts have the most severe consequences.

Answer 4

Central A-V shunts

Question 5

Pain, swelling, edema, palpable bruit/thrill [the feeling of machinery buzz if you put your hand over the skin], are all signs of what?

Answer 5

Local consequences of a peripheral A-V shunt.

Question 6

____ to _____ of aortic blood flow may be diverted into the ductus with PDAs.

Answer 6

1/2 to 1/3

Question 7

In PDAs, the ductus connects the aorta to the ______ ______. Blood then travels back to the lungs, down to the left atrium and then the left ventricle again. Over time this leads to left ventricular hypertrophy and left sided heart failure.

Answer 7

Pulmonary artery

Question 8

What is Elsenmenger Syndrome?

Answer 8

Condition associated with some high flow shunts [VSDs and PDAs].

Question 9

With high flow shunts the flow is typically from ______ to ______, except over time it becomes ______ to ______ which leads to cyanosis and is typically an irreversible change.

Answer 9

Left to right.

Right to left.

Question 10

With portosystemic shunts, blood bypasses the liver and enters systemic circulation via the ______ _______ _______.

Answer 10

Caudal vena cava

Question 11

Congenital extrahepatic shunts are mostly associated with ______ ______ ______, these are also the most common type of shunts.

Answer 11

Small breed dogs [like Yorkshire terriers.]

Question 12

Congenital intrahepatic shunts are mostly associated with ______ _______ ______.

Answer 12

Large breed dogs [like Labs and Siberian huskies].

Question 13

Acquired multiple extra hepatic shunts are caused when we do what?

Answer 13

Try to treat a portosystemic shunt and we end up causing portosystemic hypertension. (changing the blood flow somehow).

Question 14

The most common shunt for is the ______ ________ ______ _______ ______.

Answer 14

Single extrahepatic portal systemic shunt

Question 15

Extrahepatic shunts occur when you have different types of veins (like the portal vein or splanchnic vein) dumping blood into the _______ ______.

Answer 15

Vena cava

Question 16

Intrahepatic shunts is where a branch of the portal vein communicates direclty with hepatic vein within the ________ _______.

Answer 16

Hepatic parenchyma

Question 17

PDV (Patent ductus venosus) is where the ______ _____ connects with the ______ _____.

Answer 17

Umbilical vein connects with the Vena Cava [thus bypassing the liver].

Question 18

The 2 different forms of portal vein hypoplasia are what?

Answer 18

1. Idiopathic noncirrhotic portal hypertension
2. Portal Vein Hypoplasia-Microvascular Dysplasia

Question 19

Multiple extrahepatic shunts develop in response to what?

Answer 19

Response to prolonged sublethal portal hypertension.

Question 20

The problem with multiple acquired shunts when performing surgery is that what?

Answer 20

Many of the branches are present in the falciform fat and can be easily nicked during surgery.

Question 21

Hepatic arteriovenous malformation is where you have multiple aberrant shunting vessels resulting in communication between ______ _______ and ______ _______. This results in severe portal hypertension and multiple acquired shunt formation to relieve pressure in portal vasculature.

Answer 21

Hepatic artery and Portal vein

Question 22

Hypoglycemia, hypoalbuminemia, hypocholesterolemia, hypokalemia, microcytosis, clotting factor deficiencies and stunted growth are all consequences of _______ _______ _______.

Answer 22

Portal systemic shunts [PSS].

Question 23

A dog that has a known PSS presents with head pressing, what is the most likely cause?

Answer 23

Hepatic encephalopathy

Question 24

The most common type of crystals associated with PSS are ________ ________ crystals.

Answer 24

Ammonium Biurate

Question 25

Because bile acids recirculate over and over again in systemic blood (bypassing the liver), we’d expect our bile acids test results to look how?

Answer 25

High pre- and post-prandial bile acids.

Question 26

What is wrong with this dog?

Answer 26

Nothing! Notice the iodinated contrast medium was injected into an exteriorized loop of jejunum, enters portal circulation and goes up into the liver nicely. Blood will then exit and dump into the caudal vena cava.