Pathophysiology of HTN Flashcards
What is the equation for MAP?
MAP = CO X SVR
How does renal function affect the stroke volume?
Control of the Na balance
How does renal function affect the peripheral resistance?
Renin Angiotensin System
Does an increase in CO cause HTN generally?
No. An increase in CO is rarely the cause of persistent hypertension.
What are the important humoral factors in SVR regulation?
- NE
- ATN II
What effect does aldosterone have on Na?
Enhanced Na reabsorption by the proximal tubule
Pressure Natriuresis
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.
What are the two levels at which kidneys can regulate the BP?
- Volume (Na)
- Vascular Tone (Renin-ATN)
What are volume mediated causes of HTN?
Non-renal causes
- Primary hyperaldosteronism
- Cushing’s syndrome
- Mineralocorticoid producing tumors
Renal causes
- Renal failure
- Acute glomerulonephritis
What are vasoconstrictor mediated causes of HTN?
- Pheochromocytoma
- Unilateral renal artery stenosis
- Hypercalcemia
What is most monogenic HTN due to?
Most monogenic hypertension due to increase sodium retention
Pheochromocytoma
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.
Primary Aldosteronism
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.
What type of HTN are most cases?
Essential HTN (Primary)
What are some causes of secondary HTN?
- Kidney disease.
- Renal artery stenosis
- Hyperaldosteronism
- Pheochromocytoma
How does renal artery stenosis cause HTN?
It leads to excessive production of renin
How does unilateral renal artery stenosis respond to ACE-I?
Well. It should decrease the effect of angiotensin II
How does unilateral renal artery stenosis of a solitary kidney respond to ACE-I?
Not well because there will still be a volume problem. Needs to be combined with a diuretic.
What is the main problem in unilateral renal artery stenosis of a solitary kidney OR bilateral renal artery stenosis?
HTN due to volume increase
What is the most common reason for secondary HTN?
Chronic kidney disease is the most common form of secondary hypertension
What happens ti kidneys with essential HTN?
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.
What drugs can affect the auto regulation of the kidney?
Ca2+ Channel Blockers
Myogenic Response
- 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
What happens to the pressure natriuresis curve in HTN?
There is shifting of pressure natriuresis curve to right in essential hypertension or reset at higher BP level.
