Adrenergic & Angiotensin Block in CHF Flashcards
Action of:
Hydralazine
Isosorbide
Both are vasodilators:
Hydralazine: arterial vasodilation
Isosorbide: venous vasodilation
What structure produces: Angiotensinogen \_\_\_\_\_\_\_\_\_\_ Renin ACE
Angiotensinogen: Liver
__________
Renin: Kidney Juxtaglomerular cells
ACE: lungs (but found w/in the circulation)
*note: Renin and ACE are enzymes
Major side effect of hydralazine
drug induced SLE
Major side effect of isosorbide
hypotension, headache, dizziness
Major side effect of a combination of hydralazine and isosorbide
Headache
What triggers the Juxtaglomerular cells to trigger renin release?
- low blood pressure
- sympathetic nerves
- macula densa cells in distal convoluted tubules sensing low [Na+] and send prostaglandin to JG cells
Briefly Describe how the RAAS system works
- Renin produced by the JG cells will convert Angiotensinogen to Angiotensin I.
- Angiotensin I is converted to Angiotensin II by the endothelial cells in blood vessels (ACE)
- Angiotensin II affects smooth muscles, liver, kidneys, and
How does Angiotensin II affect:
- smooth muscles?
- kidney?
- Pituitary gland?
- Adrenal gland?
- vasoconstriction → ↑ resistance
- hold on to more water → ↑ volume → ↑ stroke volume
- secretes ADH and causes 1 + 2
- secretes aldosterone and causes 2
what structure secretes ADH? Aldosterone?
ADH? pituitary gland
Aldosterone? adrenal gland
The bradykinogen system runs side by side with the angiotensinogen system. Describe it.
- why is it important to know?
- Liver produces Bradykininogen
- It is converted by KallikRENIN to Bradykinin
- Bradykinin is converted by Kinase II (ACE) to inactive fragment
*if we use ACEI, then we have a drop in angiotensin II, but also an ↑ in bradykinin
↑ Bradykinin has what effects?
- potent pulmonary irritant
- cough
- large impact on LV remodeling
- Potent vasodilator (↑ afterload reduction)
What structures does Angiotensin II act on?
- Vascular smooth muscle
- CNS and Peripheral NS
- Adrenal cortex
- Direct kidney
- Brain
What are the CNS and Peripheral NS effects of Angiotensin II?
↑ sympathetic activity
→ ↑ Arteriolar constriction
→ ↑ CO
→→ ALL LEADING TO ↑↑ ARTERIAL BLOOD PRESSURE
What are effects of Angiotensin II on the adrenal cortex?
↑ aldosterone secretion
□ →→ ↑ NA Resorption
→→ ALL LEADING TO ↑↑ ARTERIAL BLOOD PRESSURE
What are effects of Angiotensin II on the brain?
↑ ADH (from pituitary gland)
Thirst
↑ Na + H2O retention
→→ ALL LEADING TO ↑↑ ARTERIAL BLOOD PRESSURE
Effects of angiotensin II
↑ Arteriolar constriction ↑ CO ↑ NA Resorption ↑ Na + H2O retention ↑ H2O absorption ↑ H2O ingestion □ →→ ALL LEADING TO ↑↑ ARTERIAL BLOOD PRESSURE
3 ACEI we need to know
*the prils
Captopril
Enlapril
Lisinopril
Enlapril
Bid (twice a day)
Lisinopril
once a day.
Captopril
short half life: 3x a day
Side effects of ACEI
- what can do use instead?
- cough
- hyperkalemia
- angioedema
- renal dysfunction
- neutropenia
- hypotension
- if these occur: can switch over to angiotension blocker (or even hydralazine/isosorbide - iffy)
ACEI DDI
○ NSAIDS BAD!!! § Inhibit renal protective prostaglandins ○ Lithium = salt § Bump up lithium levels § Narrow therapeutic index drug □ Seizure, coma, and death ○ K+ sparing diuretics ○ Loop diuretics ○ Salt substitutes
ACEI contraindications
○ Pregnancy
○ Renal Failure
○ Bilateral renal artery stenosis
○ Angioedema
○ Hyperkalemia
>5, you should reconsider…Do ACEI and ARBs reduce morbidity and mortality?
ACE inhibitors and ARBs are recommended in patients with HFrEF and current or prior symptoms, UNLESS contraindicated, to reduce morbidity and mortality ~equal
- using the two together, does not “stack” the reduction in mortality
Difference between ACEI and ARBs
ARBs: no cough (doesnt affect bradykinin), cheaper
- same side effects
MINUS COUGH!
- same DDI
- same precautions/contraindications
Non-renin systems
what is it
- examples
can convert angiotensinogen directly to Angiotensin I □ t-p Factor
□ Catepsin G
□ Tonin
non-ACE systems
what is it
- examples
Angiotensin I can be converted to angiotensin II by Non-ACE
□ Chymase
□ CAGE
□ Catepsin G
