test 6 Flashcards
What is Hypertension
•A sustained systolic blood pressure of greater than 140 mmHg or a sustained diastolic pressure of greater than 90 mmHg
Prehypertension
• 120-139/80-89 mmHg
Stage I hypertension
• 140-159/90-99 mmHg
Stage II hypertension
• ≥ 160/ ≥ 100 mmHg
Primary (Essential) HTN
- No identifiable cause
- Most common form
- 90%
Secondary HTN
- Caused by a specific disease process
* Valve disease, coarctation of aorta, pregnancy
Diagnosis of HTN
- Repeated, reproducible measurements of elevated blood pressure
* At least three pressure readings over several weeks
* Evidence of organ damage
Risk Factors for HTN
- Advance age
- Diabetes
- Obesity
- Family history
- Stress
- Smoking
- Poor diet (high fat and sodium)
- Lack of physical activity
Complications of HTN
- Stroke
- Ischemic heart disease
- LV hypertrophy
- Aortic aneurysm
- Arrhythmias
- End organ damage
* Kidneys, eyes
most antihypertensives work by
- Reducing cardiac output and/or (HR and contractility)
- Decreasing peripheral resistance (vascular tone)
BP = CO X PVR
4 anitomical sites that control BP
1) arteries
2) veins
3) heart
4) kidneys
- all controlled by CNS (sympathetic nerves)
Cardiac output and peripheral vascular resistance are controlled by two overlapping control mechanism
- Baroreceptor reflexes
2. Renin-angiotensin-aldosterone system
Baroreceptors and the Sympathetic Nervous System
•Responsible for the rapid, moment to-moment
adjustments in blood pressure
•Located in the aortic arch and carotid sinuses
Renin-angiotensin-aldosterone System
• Baroreceptors respond to reduced arterial pressure by releasing renin
• Renin converts angiotensinogen -> angiotensin I
• Angiotensin I -> angiotensin II by Angiotensin-converting enzyme (ACE)
• Angiotensin II is a potent vasoconstrictor
• Angiotensin II decreases glomerular filtration and increases aldosterone secretion
• Aldosterone increases renal sodium and water reabsorption
-kidneys handle the long term control of BP by controlling the blood volume
More than likely to treat HTN
•Frequently more than one category of drug therapy is used to treat HTN to minimize side-effects (combination therapy)
Antihypertensive Drugs
- Angiotensin II receptor blockers
- Renin inhibitors
- ACE inhibitors
- Diuretics
- β-blockers
- Calcium channel blockers
- α-blockers
- Others
Current recommendations are to initiate
therapy with
- Thiazide diuretic
- ACE inhibitor
- Angiotensin receptor blocker (ARB)
- Calcium channel blocker
Diuretics
- Lower BP by depleting the body of sodium and water, therefore, reducing blood volume
- Safe
- Inexpensive
- Often the first-line drug of choice
- Often used in combination therapy
how does Thiazide Diuretics work
•Inhibit the Na+/Cl cotransporter in the distal tubule
•Increase sodium and water excretion causing a decrease in extracellular volume
-decrease cardiac output => decreasing BP
-decrease in PVR
Thiazide Diuretics
- Useful in combination therapy with:
* β-blockers, ACE inhibitors, ARBs, potassium sparing diuretics - Not effective in patients with inadequate kidney function because drug needs to be excreted in the tubular lumen where the transporter exists
- Can induce hypokalemia, hyperuricemia, hyperglycemia
- Not recommended during pregnancy
How do Loop Diuretics work
•Inhibit the Na+/K+/2Cl- cotransporter in the ascending limb
•Blocks Na+, K+, and 2Cl reabsorption in the kidneys
•Cause decreased renal vascular resistance
•Cause increased renal blood flow
-increases excretion of Na, K, and Cl
Loop Diuretics
- Acts promptly
- Works well in patients with poor renal function
- Can cause hypokalemia
Potassium-sparing Diuretics
- Aldosterone receptor antagonist
* Causes more sodium and water to pass into the collecting duct - Reduces potassium loss in the urine
- Used in combination with loop and thiazide diuretics to reduce potassium loss
β-blockers
•Block β1 and/or β2 receptors
•Decrease sympathetic outflow from CNS
•Decease CO
• HR and contractility
•Inhibit release of renin from kidneys -> decreases anigotensin II => decrease in PVR => decreased BP
-decrease in angiotensin II => decrease in adosterone => decrease in Na and water reabsorption => decreased CBV => decreased CO => decreased BP
-decrease in BP
β-blockers Adverse Effects
- Bradycardia
- Hypotension
- Fatigue
- Insomnia
- Sexual dysfunction
- Altered lipid pane
* Decrease HDL
* Increase triglycerides
β-blockers that can be given through IV
• Esmolol, metoprolol, and propranolol
Stop using β-blockers?
- Abrupt withdrawal may induce
- Angina
- MI
- Death
- Must be tapered over a few weeks
how do ACE Inhibitors work
- Block the angiotensin converting enzyme (ACE)
- Prevents pulmonary and renal endothelium from converting angiotensin I into angiotensin II (potent vasoconstrictor)
- Decrease angiotensin II levels in the blood
- Vasodilation of arterioles and veins
- Increase bradykinin levels
- Reduce secretion of aldosterone
* Resulting in decrease sodium and water retention
angiotensin converting enzyme (ACE) and bradykinin
- ACE is responsible for the breakdown of bradykinin
- Bradykinin Increases production of nitric oxide and prostacyclin by blood vessels
* Potent vasodilators
ACE Inhibitors: Therapeutic Uses
- Course of action in patients with diabetic nephropathy (diabetic kidney disease)
* Slows progression
* Decreases albuminuria - Standard of care following MI
Chronic treatment of ACE Inhibitors achieves
- Sustained blood pressure reduction
- Regression of LV hypertrophy
- Prevention of ventricular remodeling after MI
ACE Inhibitors: Adverse Effects
- Dry cough (number one cause of being taken off drug)
- Rash
- Fever
- Altered taste
- Hypotension
- Hyperkalemia
- Fetal malformations
how do angiotensin II receptor blockers (ARBs) work
- Block angiotensin II receptors
* Decreasing activation by angiotensin II - Produce arteriolar and venous dilation
- Block aldosterone secretion
* Lowering BP and decreasing sodium and water retention - Does not increase bradykinin levels
angiotensin II receptor blockers (ARBs) course of action in patients with
- Diabetes Mellitus (DM)
- Heart failure (HF)
- Chronic kidney disease
angiotensin II receptor blockers (ARBs) Adverse effects
- Similar to ACE inhibitors
* Less risk of cough - Should not be combined with ACE inhibitors
* Similar mechanism and adverse effects - Teratogenic (Don’t take while pregnant)
How do Renin Inhibitors work
- Directly inhibits renin
* Decreases sodium and water retention - As effective as ARBs, ACE inhibitors, and thiazides
- Should not be combined with ACE inhibitor or ARB
- Can cause diarrhea and cough
- Contraindicated during pregnancy
how do Calcium Channel Blockers work
- Prevents inward movement of calcium into heart cells and smooth muscle of the coronary and peripheral arteriolar vasculature
- Causes smooth muscle relaxation
- Dilates mainly arterioles
- Can be used as initial therapy or add-on therapy
what do α1-blockers do
- Selectively block the α1 -receptors in arterioles and venules
- Decrease PVR and BP by causing relaxation of both arterial and venous smooth muscle
- Cause reflex tachycardia and postural hypotension
- Cause salt and water retention
* Used with diuretic - Not used as initial treatment for HTN
α/β-blockers
•Labetalol and carvedilol
•Block α1, β1, and β2
receptors
• PVR and BP (block α1)
•Carvedilol is mainly used to treat heart failure
•Labetalol used to treat gestational hypertension
Clonidine (CATAPRESS)
- α2 agonist
- Decreases sympathetic outflow from CNS
* PVR and BP - Causes relaxation of venules
Clonidine: Side Effects
- Dry mouth
- Sedation
- Constipation
- Rebound HTN following abrupt withdrawal
Methyldopa (ALDOMET)
- α2 agonist
- Similar to clonidine
- Decreases sympathetic outflow from CNS
- Used to treat HTN during pregnancy
how does hydralazine work
- Causes reflex stimulation of heart
* Increased contractility, HR, and oxygen consumption
* Causes angina, MI, or heart failure - Increases renin causing sodium and water retention
- Used in conjunction with a β-blocker and diuretic to reduce side effects
- Can be used during pregnancy
- Can cause lupus-like syndrome at high doses
Minoxidil: Side Effects (vasodilator)
- Severe tachycardia
* Dose-dependent - Palpitations
- Angina
- Headache
- Sweating
- Hypertrichosis
* Excessive hair growth - Co-administered with β-blocker and diuretic
Nitroprusside: Side Effects
- Accumulation of cyanide (cyanide poisoning)
* Use is limited to 3 days or less - Arrhythmias
- Excessive hypotension
Treatment of HTN on Pump
- Flow
- Anesthetic depth
- Drugs
