Hypertension Flashcards
What is the diagnosis of HTN based on?
Measurements not symptoms
What is required to make a diagnosis of HTN?
The average of 2 or more blood pressure readings taken at each of two or more visits after an initial screening.
What is the prehypertension BP classification?
SBP- 120-139 mmHg OR DPB- 80-89 mmHg
What is the stage 1 hypertension BP classification?
SBP- 140-159mmHg OR DBP 90-99mmHg
What is the stage 2 hypertension BP classification?
SBP- >/= 160mmHg OR DBP >/=100mmHg
What are the risk factors associated with the development of CV dz?
In those older than age 50, systolic blood pressure (SBP) of >140 mmHg is a more important cardiovascular disease (CVD) risk factor than diastolic BP (DBP)
Beginning at 115/75 mmHg, CVD risk doubles for each increment of 20/10 mmHg
Those who are normotensive at 55 years of age will have a 90 percent lifetime risk of developing hypertension
Every _____ mmHg increase in SBP or ______ mmHg increase DBP doubles the risk of cardiovascular dz?
Every 20 mmHg increase in SBP or 10 mmHg increase in DBP doubles the risk of cardiovascular disease
What are the benefits of antihypertensive therapy?
35-40% reduction in stroke
20-25% reduction in myocardial infarction
>50% reduction in heart failure
What are the mechanisms for controlling blood pressure?
Mean arterial pressure= CO x PVR
Baroreceptor/sympathetic nervous system
Renin-angiotensin-aldosterone system
Is baroreceptor/SNS short or long term controlled? And what receptors is is mediated by?
Short-term controlled
Mediated by beta1 receptors in the heart
Mediated by alpha1 receptors in arterioles
Is renin-angiotensin-aldosterone system short or long term control?
Long term control
What is the early function of the proximal tubules?
Organic solutes and sodium bicarbonate are reabsorbed.
Na+/H+ exchanger on luminal membrane
H+ combines with filtered HCO3- to make carbonic acid => Carbonic Anhydrase=> H20 and CO2 in cell
What is the late function of the proximal tubule?
Sodium chloride reabsorption
Na+/H+ exchanger continues w/o bicarbonate causing luminal pH to drop
Activates Cl-/base exchanger causing NaCl reabsorption
What is the function of the thin limb of the loop of henle?
Does not participate in NaCl reabsorption
Does participate in H20 absorption (osmotic)
What is the function of the thick ascending limb (diluting segment) in the loop of henle?
Actively reabsorbs 35% of filtered NaCl (2Cl-/Na+K+ pump)
Impermeable to water – dilutes tubular fluid
K+ increases in cell secondary to interstitial Na/K ATPase which is then luminally excreted
Resultant electrochemical gradient drives Ca2+ and Mg2+ reabsorption via intercellular pathways
What is the function of the distal convoluted tubule?
- Actively reabsorbs 10% filtered NaCl via Na/Cl pump (pharmacologically distinct- drugs that target the first pump don’t affect this pump)
- Impermeable to water – further dilution
- No potassium recycling across interstitial membrane (no Ca2+ or Mg2+ exchange)
- Active calcium reabsorption under influence of PTH
What is the function of the collecting tubule?
–2-5% NaCl reabsorption – Not active
Principal cells – separate ion channels for Na
–Major site of potassium secretion – more Na absorbed greater K excretion
Regulated by aldosterone
–Active hydrogen ion excretion via the intercalated cells
–ADH activity – regulates water permeability, therefore, volume and concentration
What is the major site of potassium secretion in the kidney?
Collecting tubule
What is the primary therapeutic objective for HTN?
Reduction of blood pressure
Limit the development of subsequent organ damage
Reduction of blood pressure is done by drugs whose MOA do what?
Alter blood volume
Cardiac output (HRxSV)
Peripheral vascular resistance
Limiting development of subsequent organ damage includes limiting what?
LVH, angina, MI, heart failure, stroke, chronic kidney disease, peripheral arterial disease, retinopathy
What is another name for primary HTN?
Essential HTN
What causes primary HTN?
Cause unknown 90% of all cases Risk Factors: Age Genetic predisposition Obesity ETOH Smoking Physical inactivity
What causes secondary HTN?
Identifiable cause:
Vascular disease
Endocrine disorders- DM
Drugs – Corticosteroids, anorexiants/decongestants, thyroid hormone excess, OCPs, NSAIDs/COX-2, occassionally TCA’s and venlafaxine, excessive licorice
What are the signs of HTN?
Elevated BP often the only sign
Other signs may develop due to complications of the disease:
retinal hemorrhages, AV nicking, arteriolar narrowing
neurologic deficits
extra heart sounds
left ventricular hypertrophy
What are the symptoms of HTN?
Often asymptomatic Symptoms often due to complications of the disease: cardiovascular cerebrovascular renal
What is step 1 to the step by step approach to treatment of HTN?
Decide whether or not drug therapy is indicated
What is step 2 to the step by step approach to treatment of HTN?
Establish a treatment goal
No diabetes, no kidney dz: goal <130/80 mmHg
What is step 3 to the step by step approach to treatment of HTN?
Promote lifestyule modification
- Weight reduction
- Adopt DASH eating plan
- Dietary sodium restriction
- Physical activity
- Moderation of alcohol conumption
What is DASH?
Dietary Approaches to Stop Hypertension (diet rich in potassium and calcium)
What is step 4 to the step by step approach to treatment of HTN for stage 1?
(without compelling indications)
1st choice Thiazide
2nd choice ACEI, ARB, BB, CCB, or combination
What is step 4 to the step by step approach to treatment of HTN for stage 2?
(without compelling indications)
2-drug combination for most:
Thiazide + ACEI, or ARB, or BB, or CCB
What is the initial treatment for normal BP classification?
None
What is the initial treatment for prehypertension BP classification?
No comorbities: lifestyle modification
Comorbidities: drug therapy
What is the initial treatment for stage 1 HTN BP classification?
Drug therapy
What is the initial treatment for stage 2 HTN BP classification?
Drug therapy (usually two drugs required)
What are the treatments for heart failure?
1st choice: ACEI* +BB
2nd choice :Aldosterone antagonist or Amlodipine or Felodipine or Thiazide
What are the treatments for coronary artery disease?
1st choice: BB + ACEI*
2nd choice: Amlodipine or Felodipine or Thiazide
What are the treatments for diabetes?
1st choice: ACEI or ARB
2nd choice: BB or Thiazide or CCB
What are the treatments for chronic kidney disease?
1st choice : ACEI or ARB
2nd choice: BB or CCB
What are the treatments for recurrent stroke?
1st choice: ACEI + Thiazide
2nd choice: BB or ARB or CCB
What are the treatments for systolic hypertension?
1st choice : Thiazide
2nd choice: Long-acting dihydropyridine CCB
What can be used in patients that are unable to take ACE inhibitors?
ARB (angiotensin receptor blockers)
Can mild HTN be controlled by a single drug?
Yes and frequently
What does drug choice for treatment of HTN depend on?
Race, ace, concurrent illnesses
What are 50% of failures of tx of HTN due to?
Noncompliance
What is step 5 to the step by step approach to treatment of HTN?
Follow up and monitoring
Should occur monthly until BP is reached.
SrCr should be drawn 1-2x yearly
Once BP is at goal and stable, follow up can occur every 3-6 months; more frequently if the patient has other co-morbidities.
What is the failure to reach goal BP in patients who are adhering to full doses of a 3 drug regiment that includes a diuretic?
Resistant hypertension
What should be done for resistant HTN?
Work up for underlying medical conditions
Some patients may require 6-7 drugs in this situation.
Target tissues for anti-hypertensive agents include?
- -The sympathetic nerves which release the vasoconstrictor NE
- -The kidney which regulates blood volume
- -The heart which generates CO
- -The arterioles which determine PVR
- -Endothelial cells which regulate circulation levels of the endogenous hypertensive and hypotensive agents such as angiotensin II and NO, respectively
- -The CNS, which senses the BP and controls set point by regulating some of the systems involved.
What are drugs affecting body sodium balance?
Diuretic and dietary manipulation of sodium balance
What are the mechanisms that increase vascular resistance due to excessive body sodium?
increased vessel rigidity
increased fluid retention
increased release of norepinephrine and epinephrine from sympathetic terminals and adrenal medulla
How does dietary sodium restriction help HTN?
- -The restriction of dietary sodium alone can significantly decrease arterial pressure although to varying degrees in patients with essential hypertension.
- -Obese subjects have a more pronounced decrease in arterial pressure with sodium restriction.
- -The restriction of dietary sodium can markedly improve the efficacy of antihypertensive drugs.
What is recommended as first line therapy for uncomplicated HTN (monotherapy or adjunctive)?
Diuretics
What are diuretics proven to do?
Decrease sick of stroke, MI, CHF, and total mortality
Does antihypertensive action correlate with diuretic activity?
No
Hydrochlorothiazide (HCTZ)-MOA
Thiazide diuretic
Inhibit luminal NaCl transport in distal tubule
Changes in urine ionic content –> increase loss of Na+, K+, water
Short-term - sodium & water excretion = decreases plasma volume
Long-term - decrease peripheral vascular resistance
Hydrochlorothiazide (HCTZ)- therapeutic uses
- -HTN - thiazide diuretics lose efficacy as renal function declines and are generally not used if creatinine clearance is < 30 mL/min
- -CHF- thiazide diuretic + loop diuretic = synergistic diuretic effect
- -Nephrogenic diabetes insipidus
- -Prevent kidney stones due to hypercalciuria