Pathophysiology of HTN

Question 1

What is the equation for MAP?

Answer 1

MAP = CO X SVR

Question 2

How does renal function affect the stroke volume?

Answer 2

Control of the Na balance

Question 3

How does renal function affect the peripheral resistance?

Answer 3

Renin Angiotensin System

Question 4

Does an increase in CO cause HTN generally?

Answer 4

No. An increase in CO is rarely the cause of persistent hypertension.

Question 5

What are the important humoral factors in SVR regulation?

Answer 5

• NE

- ATN II

Question 6

What effect does aldosterone have on Na?

Answer 6

Enhanced Na reabsorption by the proximal tubule

Question 7

Pressure Natriuresis

Answer 7

Regulation of the extracellular fluid volume by coupling increasing or decreasing urinary excretion of Na and water and related changes in blood volume and cardiac output to changes in renal perfusion pressure.

Question 8

What are the two levels at which kidneys can regulate the BP?

Answer 8

• Volume (Na)

- Vascular Tone (Renin-ATN)

Question 9

What are volume mediated causes of HTN?

Answer 9

Non-renal causes

1. Primary hyperaldosteronism
2. Cushing’s syndrome
3. Mineralocorticoid producing tumors

Renal causes

1. Renal failure
2. Acute glomerulonephritis

Question 10

What are vasoconstrictor mediated causes of HTN?

Answer 10

1. Pheochromocytoma
2. Unilateral renal artery stenosis
3. Hypercalcemia

Question 11

What is most monogenic HTN due to?

Answer 11

Most monogenic hypertension due to increase sodium retention

Question 12

Pheochromocytoma

Answer 12

A tumor of adrenal medulla which produces excessive amounts of epinephrine and nonepinephrine. This increased level of catecholamine produces severe hypertension due to intense vasoconstriction.

Question 13

Primary Aldosteronism

Answer 13

A tumor or hyperplasia of adrenal cortex leads to increased production of aldosterone. Aldosterone leads to sodium retention and expanded volume leading to severe hypertension. This is pure volume expansion.

Question 14

What type of HTN are most cases?

Answer 14

Essential HTN (Primary)

Question 15

What are some causes of secondary HTN?

Answer 15

• Kidney disease.
• Renal artery stenosis
• Hyperaldosteronism
• Pheochromocytoma

Question 16

How does renal artery stenosis cause HTN?

Answer 16

It leads to excessive production of renin

Question 17

How does unilateral renal artery stenosis respond to ACE-I?

Answer 17

Well. It should decrease the effect of angiotensin II

Question 18

How does unilateral renal artery stenosis of a solitary kidney respond to ACE-I?

Answer 18

Not well because there will still be a volume problem. Needs to be combined with a diuretic.

Question 19

What is the main problem in unilateral renal artery stenosis of a solitary kidney OR bilateral renal artery stenosis?

Answer 19

HTN due to volume increase

Question 20

What is the most common reason for secondary HTN?

Answer 20

Chronic kidney disease is the most common form of secondary hypertension

Question 21

What happens ti kidneys with essential HTN?

Answer 21

Essential Hypertension leads to hypertensive nephrosclerosis is also known as benign nephrosclerosis.

In early stages of hypertension, there is no histological abnormality noticed in kidneys. But over the course of time, there is gradual loss of nephron mass with progressive reduction of kidney size caused by cortical atrophy and fibrosis. This is secondary to afferent arteriolar hyalinization.

Question 22

What drugs can affect the auto regulation of the kidney?

Answer 22

Ca2+ Channel Blockers

Question 23

Myogenic Response

Answer 23

• Response to increased afferent arteriolar pressure:
  • stimulates reflexive vasoconstriction by stimulating smooth muscle cell contraction
• Response to decreased afferent arteriolar pressure:
  • stimulates reflexive vasodilation by stimulating vascular smooth muscle relaxation

Question 24

What happens to the pressure natriuresis curve in HTN?

Answer 24

There is shifting of pressure natriuresis curve to right in essential hypertension or reset at higher BP level.