Renovascular hypertension and Renal Artery Stenosis

Question 1

What is renovascular hypertension?

Answer 1

elevated BP caused by conditions that interfere with circulations to kidney.

Often can coexist with other causes of HTN e.g. essential hypertension.

accounts for 1-3% of all causes for hypertension

Question 2

Why is renovascular hypertension considered a continuum of disease?

Answer 2

Can range from:
Asymptomatic incidental renal artery stenosis
to renovascular hypertension
to accelerated cardiovascular disease, CHF, stroke
to ischaemic nephropathy.

Question 3

Pathogenesis of renovascular HTN

Answer 3

need >80% of stenosis to see changes in flow/pressure.

involves activation of RAAS and depends on the presence/absence of contralateral kidney

Question 4

RAAS activation:

Answer 4

Renal ischaemia -> renin production
ANG -> via renin -> ANG 1 -> ACE -> ANG2

ANG2 causes:

1) ↑ Aldosterone → ↑ sodium retention → ↑ cardiac output → ↑ LV hypertrophy, myocyte growth+remodelling
2) vasoconstriction → ↑ peripheral resistance → ↓cardiac output

Overall raised BP

Question 5

Pathophysiology of HTN in unilateral renal artery stenosis

Answer 5

Kidney with stenosis:

• reduced renal perfusion
• RAAS activation
• Renin -> ANG 2 -> aldosterone = HTN

Normal kidney:

• increased renal perfusion
• reduced RAAS
• Na+ excretion via pressure natriuresis.

Overall HTN is due to ANG2, but no fluid overload element.

Question 6

Pathophysiology of HTN in bilateral renal artery stenosis or stenosis of solitary kidneys

Answer 6

Overal reduced renal perfusion:

-