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Cardiac Diagnostic Studies (PowerPoint)

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					Hypertension: the silent killer




     Leslie Mickles, RN, MSN
             Statistics
• Afflicts almost 1 billion people
  worldwide and is a leading cause of
  morbidity and mortality.
• More than 20% of Americans are
  hypertensive, and one-third of these
  Americans are not even aware they are
  hypertensive.
  Blood Pressure Physiology
Pressure in cardiovascular system controlled by:

•Heart rate
•Stroke volume:
  • Actual blood volume
  • Contractility
•Total peripheral resistance:
  • small arterioles are most important due to small
    diameter and ability to constrict to the point of
    almost stopping blood flow.
    Compensatory Mechanisms
         Effecting BP
• Baroreceptor reflex
  • Carotids and Aortic Arch
  • Brainstem to the vasomotor centre (VMC)
  • Activation of the sympathetic nervous system
    • increased contractility of the heart (beta receptors)
    • vasoconstriction of both the arterial and venous
      side of the circulation (alpha receptors)
• Renin-angiotensin system (RAS)
• Aldosterone release
Renin Angiotensin Cycle
                    Receptor
     Tissue                                     Stimulation Causes
                    Subtype
                               Stimulation of these receptors in the heart produces a
                               more rapid heart rate as well as more forceful heart
Heart Muscle                   muscle contractions. Drugs that stimulate beta1
                     beta 1
and Fatty Tissue
                               receptors may, therefore, be useful in the treatment of
                               clients with depressed cardiac function
                               Stimulation of the beta2 receptors in bronchial muscle
Smooth Muscle                  results in muscle relaxation, thereby increasing the
of the Peripheral              diameter of the air channels and promoting improved
Vasculature and      beta 2
                               gas exchange. Beta2 stimulants (agonists) are sometimes
Airway
                               used, therefore, to treat bronchial asthma or other
(bronchial)
                               conditions marked by breathing difficulty.
                               When alpha1 (α1) receptors are stimulated, either by a
Peripheral Blood               neurotransmitter or a drug, the smooth muscle
Vessels and                    associated with them contracts. This contraction may
                     alpha 1
Sphincters of GI
                               result in an increase in blood pressure due to
and GU Tracts
                               constriction of peripheral blood vessels.

                               These receptors seem to function as “controllers” of
Located on the                 neurotransmitter release by the presynaptic neuron.
Presynaptic          alpha 2   Inhibition of tansmitter release causes hypotension,
Neuron
                               anaesthesia, vasoconstriction
                       Receptor Sites Stumulation

alpha-receptor                    beta-receptor

vasoconstriction                  vasodilation (b2)

iris dilation                     cardioacceleration (b1)

intestinal relaxation             intestinal relaxation (b2)


intestinal sphincter
                                  uterus relaxation (b2)
contraction


bladder sphincter contraction     bronchodilation (b2)
  Hypertension Definitions
• Hypertension is a systolic BP >140 and
  a Diastolic BP >90 based on the average
  of two or more correct blood pressure
  measurements taken during two or
  more contacts with a health care
  professional.
    Types of Hypertension
• Primary (essential) Hypertension:
  means the cause can not be identified
  (90-95%)

• Secondary Hypertension: cause can be
  traced to some underlying disorder (e.g.
  renal disease, tumor of the adrenal
  medulla) 5%
      Identifiable Causes
• Drug induced
• Renal failure
• Primary aldosteronism
• Renovascular disease
• Thyroid and parathyroid disease
           Risk Factors
• Smoking
• Age
• Gender
• Race
• Family history
• Obesity
• Stress
• Excess Sodium intake
• Alcohol intake
• Elevated serum lipids
       Cultural Considerations
African Americans develop hypertension earlier in life, and
it is more severe at any decade of life. The estimated
prevalence of individuals with hypertension in the
population at large is as follows:

POPULATION                 MALES               FEMALES
American Indians           26.8%               27.5%
African Americans          35.0%               34.2%
Anglo-Americans            24.4%               19.3%
Asian/Pacific Islanders    9.7%                8.4%
Cuban Americans            22.8%               15.5%
Mexican Americans          5.2%                22.0%
Puerto Ricans              15.6%               11.5%

(American Heart Association, 1999d)
        Aging Effect on BP
• As one ages there is an accumulation of
  atherosclerotic plaque in arteries.
• Arteries become less elastic.
• Since arteries are less elastic the arterial
  pressure is elevated with the force of
  blood being pumped out from the left
  ventricle.
BP         SBP       DBP     Lifestyle Meds
Class      (mm Hg)   (mm Hg) Mod

Normal <120          <80      Enc     No meds
                                      indicated
PreHTN 120-139       80-89    Yes     No Meds
                                      indicated
Stage I    140-159   90-99    Yes     Thiazide
HTN                                   Diuretics,
                                      (poss ACE,
                                      CCB.ARB,
                                      BB)
Stage II    160      100    Yes     Two meds
HTN
 Target Organs Damaged by
        Hypertension
• Heart (Angina, MI, hypertrophy,
  failure)
• Brain (TIA or Stroke)
• Eyes (loss of vision, retinopathy)
• Kidneys (chronic renal failure)
• Peripheral artery disease
         Manifestations
• Retinal hemorrhages
• Visual changes
• Papilledema (swelling of the optic
  nerve)
• Headaches
• Heart failure, or chest pain
• Slurred speech, hemiparesis, weakness
  – suggestive of TIA (temporary) or CVA
• Elevated BUN and Creatinine
                  Treatment
• Identify underlying cause if possible
• Keep BP <140/90
• Stepped Care Approach
  • Step I: Life style modifications: wt reduction, restrict
    Na intake, stop smoking, reduce alcohol consumption,
    reduce stress, increase exercise.
  • Step II: One medication started, usually a diuretic, but
    may be an ARB, ACE inhibitor or calcium channel
    blocker.
  • Step III: If ineffective, change dose or class of
    antihypertensive med or add a second medication.
  • Step IV: Adjustment of previous dosages, and addition
    of another antihypertensive med until desired control
    of BP obtained. Note many medications come as a
    fixed combination of drugs
      Hypertensive Crisis
• Hypertensive Emergency:
  • A situation in which the BP must be
    lowered immediately to halt damage to
    target organs
• Hypertensive Urgency;
  • situation in which BP must be lowered
   with a few hours.
       Hypertensive Crisis
• Treatment:
  • Arterial line
  • Intravenous medication – typically nipride
    or nitroglycerin
  • May also use cardene, or IV vasotec
  • Lower BP but with MDs parameters.
    Typically not below 140/90 or you will
    impede cerebral perfusion
  • Supportive care for any symptomatology
     Hypertensive Urgency
• Managed with oral medication such as
  • Fast acting loop diuretics (Lasix, Bumex)
  • ACE inhibitors, ARBs, calcium channel
    blockers, beta blockers
• Close monitoring of BP – A line or
  Dynamap cycling
                     Loop Diuretics
Action             Named because the work int eh loop of Henle. Block the
                   chloride pump in the ascending loop of Henle (where
                   normally 30% of all filtered Na is reabsorbed) decreasing Na
                   reabsorption and producing copious amounts of urine.
Naming             Generic names tend to end in “…ide” i.e. furosemide (Lasix),
                   bumetanide (Bumex), torsemide (Demadex).
Indication         Used in treatement of severe edema, acute pulmonary
                   edema, CHF or hypertension because they can precipitate the
                   lose of up to 20 lbs of water per day. Preferred diuretic for
                   rapid and extensive diuresis.
Contraindication   Hypersensitivity, electrolyte imbalance, anuria, severe renal
                   failure, hepatic coma, pregnancy and lactation.

Adverse Effects    Hypokalemia, alkalosis (due to lose of bicarb with urine),
                   hypotenison, dizziness, ototoxicity and even deafness,
                   hyperglycemia (with long term use), dehydration/
                   hypovolemia.
Nursing            Teaching regarding daily weights, potassium replacement.
Considerations     Report signs of hypotension or hypovolemia. Also monitor
                   BUN and creatinine to ensure not overly dehydrated.
                   Thiazide Diuretics
Action              Belong to the chemical class of drugs called sulfonamides.
                    They work by blocking the chlorides movement out of the
                    renal tubules (and thereby Na+ movement). Blocking the
                    chloride pump keeps the Na and Cl in the tubules for
                    excretion in the urine.
Naming              Generic name tends to end in “….thiazide” i.e.
                    hydrochlorothiazide (Hydrodiuril), chlorothiazide (Diuril),
                    bendroflumethiazide, (Naturetin), hydroflumethiazide
                    (Saluron), methyclothiazide (Enduron)
Indication          Monotherapy or adjunctive thearpy for hypertension. Also,
                    treatement of edema associated with CHF or with liver or
                    renal disease. Mild diuretics compared to loop diuretics.
Contraindication    Hypersensitivity, fluid or electrolyte imbalance, renal and/or
                    liver disease. Pregnancy and lactation.
Adverse Effects     GI upset, CNS complications, hypovolemia, hypokalemia,
                    hypovolemia/dehydration.
Nursing             Monitor fluid and electrolyte balance closely, especially for
Considerations      hypokalemia. Hypokalemia may cause leg cramps and
                    cardiac arrhythmias. Also monitor BUN and creatinine to
                    ensure not overly dehydrated.
    Potassium Sparing Diuretics
Action             Potassium-sparing diuretics decrease sodium reabsorption at
                   collecting tubules, inducing diuresis; decrease activity of
                   aldosterone at collecting tubules.

Naming             No common ending to their names. Include: amiloride
                   (Midamor), sprionolactone (Aldactone), and triamterene
                   (Dyrenium)
Indication         Particularly useful in treating hypertension and edema
                   associated with CHF in patients at high risk if hypokalemia
                   would develop (i.e. patients on digoxin). Drug of choice for
                   hyperaldosteronism.
Contraindication   Hypersensitivity, hyperkalemia, renal disease, or anuria.


Adverse Effects    Hyperkalemia which can lead to lethargy, confusion, ataxia,
                   muscle cramps and cardiac arrhythmias.

Nursing            Closely monitor fluid and electrolyte balance (especially K+).
Considerations     Also monitor BUN and creatinine to ensure not overly
                   dehydrated.
         Vasodilators: Nitroprusside
Action            Liberates nitric oxide (-NO)spontaneously in solution and thus
                  causes arteriolar and venous dilitation.
Indication        Nipride is indicated for immediate reduction of BP in
                  hypertensive crisis. Also utilized post-op to control blood
                  pressure and reduce bleeding (i.e. post craniotomy). Utilized to
                  reduce afterload and preload and thereby improving Cardiac
                  Output in CHF and Cardiogenic Shock.

Contraindication Hypersensitivity to nitroprusside or any component of the
                 formulation; treatment of compensatory hypertension (aortic
                 coarctation, arteriovenous shunting)
Adverse Effects   Cyanide toxicity. Thiocynate levels > 100 mcg/ml may cause:
                  drowsiness, lethargy, nausea and vomiting and muscle
                  twitching progressing to convulsions and coma. High
                  concentrations suppress thyroid function
Nursing           Light sensitive. Infusion bag must be covered to block light and
Considerations    changed every 24 hours to prevent more rapid degredation to
                  thicynate. Monitor for manifestation of cyanide toxicity.

				
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