Lecture 6: Renovascular Hypotension

Question 1

What is renovascular hypotension?

Answer 1

Restriction of blood flow to the kidneys, development of cysts and atheroma

Question 2

What is atheroma?

Answer 2

Degeneration of artery walls due to fatty deposits that restrict circulation

Question 3

What is the level of renal blood flow?

Answer 3

20% of CO, 1L/min

Question 4

What happens when an organ commands more blood flow?

Answer 4

Has higher component to TPR

Question 5

What is the occurrence of ADPKD?

Answer 5

1/700

Question 6

What are the 10% of ADPKD cases with no family history due to?

Answer 6

• De novo mutations

- False paternity

Question 7

Where do cysts form in ADPKD?

Answer 7

Kidney 100%
Stomach, gall bladder, spleen 80%
Liver 70%
Heart 15%
Vessels 10%

Question 8

What do the cysts in ADPKD cause?

Answer 8

Cysts take over kidney and exert pressure on arteries - making them travel further distances and reduced diameter (restricting blood to kidneys)

Question 9

When do people present with ADPKD?

Answer 9

Early in life

Question 10

When do cysts appear in ADPKD?

Answer 10

In utero

Question 11

What percentage of nephrons do ADPKD cysts form from?

Answer 11

1%

Question 12

How do the ADPKD cysts survive?

Answer 12

Grow and separate from tubule - produce own fluid to survive - basement membrane is functioning abnormally and is allowing the cysts to grow past normal levels

Question 13

What genes are mutated in ADPKD?

Answer 13

PKD1: ch16, polycystin 1, 85%
PKD2: ch4, polycystin 2, 15%

Question 14

Whys is renal plasma flow low, but GFR normal in ADPKD?

Answer 14

GFR normal because Ang II tightens post glomerular capillaries to maintain pressure

Question 15

Where is renin found?

Answer 15

JGAs, vessels, cells lining cyst wall

Question 16

How much urine must you secrete daily?

Answer 16

At least 500mL

Question 17

What is the most concentrated you can make your urine?

Answer 17

1200mOsm

Question 18

What is renal artery stenosis?

Answer 18

Narrowing of renal arteries

Question 19

When is stenosis significant?

Answer 19

When there is >70% obstruction to renal blood flow

Question 20

What causes stenosis?

Answer 20

Atheroma (70%): environmental causes
Fibromuscular Dysplasia (25%): genetic, in young people (women) who don't have risk factors

Question 21

What is fibromuscular dysplasia?

Answer 21

Abnormal growth of renal arteries and presence of twists and obstructions

Question 22

Whys is plasma renin increased in 50% of patients with renal artery stenosis?

Answer 22

Because blood flow to the kidney is restricted so the kidney detects this as a reduced blood pressure

Question 23

What happens if you treat people with renal artery stenosis with ACE inhibitors?

Answer 23

Renal Failure

People with renal artery stenosis need RAS system to overcome narrowing of arteries - need to increase renal capillary blood pressure to maintain blood flow, flirtation and avoid failure