The Heart

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The Heart

• Chapter 14
• BS

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Traveling Through the HeartCirculation

• The continuous one-way movement of the blood
• The prime mover that propels blood throughout the
  body is the heart

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The Heart

• Is slightly bigger than your fist, weighs about 1
  pound
• It is located between the lungs in the center and
  a bit left of the midline (5th intercostal space,
  mid-clavicular)
• The apex of the heart is the point and it is
  pointed towards the left
• The heart beats, this is called contractions or
  strokes, it usually beats on average of 72 beats
  per minute and carries on for a whole lifetime
  (hopefully)

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Structures of the Heart

• There are 3 different tissue layers of the heart,
  middle, inner and outer
• The inner most layer has 4 important layers
  itself
• Endocardium
• Myocardium
• Epicardium
• Pericardium

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Endocardium

• This lines the interior of the heart and chambers
  and forms the valves
• (open the door to the model and you can see the
  endocardium)

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Myocardium

• This is the thickest layer,
• this is known as the
• working layer
• Meat Potatoes of the heart,
• this is the lower, meaty part of
• the heart
• This part is so meaty, it needs its own
  circulation system (coronary circulation)
• Here, contraction of 1 fiber causes the whole
  group to contract

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Epicardium

• This is the outer covering of the heart
• Along with the serous lining of the pericardial
  cavity, this layer forms the pericardium
• Epicardium and pericardium are basically the same
  thing

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Pericardium

• This layer contains
• serous fluid
• This is the double
• membranous fibroserous
• sac that encloses the heart
• and the organs of the great vessels
• This layer holds the heart in place
• This layer touches the epicardium, they look like
  2 pieces of glass with water between them, they
  slide when the heart contracts

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Cells of the heart

• The cells of the heart are striated to allow for
  rapid transfer of electrical impulses between the
  cells
• Another feature of cardiac muscle tissue is that
  it branches. This branching allows for the
  contraction of one fiber to lead to the
  contraction of a whole group of fibers, this is
  important in the working of the heart muscle

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Right Heart vs. Left Heart

• The human heart is really a double pump
• RIGHT SIDE LEFT SIDE
• Pumps blood low in pumps oxygenated blood
• Oxygen to the lungs to the rest of the body
• The 2 sides are completely divided by a septum -
  a septum is a wall dividing 2 cavities.

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Septum of the heart
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Blood Flow through the heart

• Blood enters the superior and inferior vena cava
• Enters the Right atrium
• Travels through the Tricuspid valve
• before it enters into the Right ventricle, it
  goes
• Through the pulmonary valve
• Out the pulmonary artery to the lungs and picks
  up O2
• Out of the lungs and up into the pulmonary vein
• Through the Left atrium and mitral valve or
  bicuspid valve
• Down through the Left ventricle and out the
  aortic valve
• Out into the aorta and to the brain and body

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There are 4 chambers to the heart

• 1. Right Atrium
• 2. Right Ventricle
• 3. Left Atrium
• 4. Left Ventricle

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Right Atrium

• Thin walled chamber
• Receives blood from the superior and inferior
  vena cava returning from the body tissues
• This blood contains low O2
• Superior vena cava brings blood from the head and
  chest and arms
• Inferior vena cave brings blood from the trunk of
  the body and the legs

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Right Ventricle

• Pumps the venous blood received from the right
  atrium into the lungs
• It pumps into a large pulmonary trunk which then
  divided into right and left pulmonary arteries
  which branch to the lung

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Left Atrium

• Receives blood high in oxygenation through the
  pulmonary vein right from the lungs

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Left Ventricle

• This chamber has the thickest wallwhy???
• It pumps oxygenated blood to all parts of the body

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Broken ventricles or premature ventricular beats

• What will the patient look like?

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Four Valves

• These valves work one way directing the flow of
  blood through the heart, they keep the blood from
  flowing backwards
• These valves are located at the entrance and exit
  of each ventricle
• These valves opening and closing is what makes
  the lub-dub heart sounds

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Lub-Dub Sounds

• Closure of the atrioventricular valves makes the
  first heart sound lub
• Closure of the semilunar valves makes the second
  heart sound - dub

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Entrance Exit Valves

• Entrance Valves Exit Valves
• Atrioventricular semi-lunar
• Tricuspid/bicuspid pulmonic valves
  aortic valves

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Chordae tendineae

• Thread-like cords that connect the free edges of
  the atrioventricular valves to the papillary
  muscles in the ventricles

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Blood supply to the myocardium

• Remember when we talked about the myocardium?
• The myocardium is the muscle of the heart, it is
  the thickest layer and is responsible for pumping
  blood through the vessels.
• The layer under the myocardium, the lining that
  is around the interior of the heart, is called
  the endocardium. This lining comes in contact
  with the blood flow through the heart chambers

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Blood flow through the heart chambers

• Is called coronary circulation, it consists of
• Right coronary arteries
• Left coronary arteries

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• BIG PROBLEM WHEN CIRCULATION STOPSgtgtgtgtgtgtgtgtgtgtgt

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Blockage of coronary arteries

• Causes dull and heavy pain that may radiate to
  the arm, jaw, or back
• Pt describes the pain to be vise-like, or
  producing a feeling of compression or squeezing
  of the chest
• Decreased blood flow to the coronary arteries
  causes angina pectoris (chest pain) or M.I.
• C.A.D.coronary artery disease usually caused by
  plaque build-up, leads to angina or M.I.

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Blocked Coronary Artery
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Coronary Artery Occlusion
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The work of the heart

• Although the Left and Right side of the heart are
  separated from each other, they work together
• Blood is squeezed through the chambers by a
  contraction of heart muscle beginning in the
  thin-walled upper chambers called the atria,
  followed by a contraction of the thick muscle of
  the lower chambers called the ventricles. This
  is the lub-dub sound

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The active an inactive phase

• Systole contraction of the chambers of the
  heart. The myocardial fibers shorten making the
  chamber smaller and forcing blood out (this is
  the active phase)
• Diastole The normal period in the heart cycle
  during which the muscle fibers lengthen, the
  heart dilates, and the cavities fill with blood.
  (this is the inactive phase)

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Cardiac Output

• A unique property of the heart is its ability to
  adjust the strength of a contraction to the
  amount of blood received
• If I am at rest, not much contraction is needed
• If I am exercising, blood needs to get pumped out
  forcefully to meet my oxygen needs, the heart has
  the ability to do this

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Cardiac Output

• Is the volume of blood pumped by each ventricle
  in 1 minute
• Cardiac output is determined by multiplying the
  stroke volume by the heart rate SV x HR
• Stroke volume is the amount of blood ejected by
  the left ventricle at each heartbeat, is around
  70ml/beat
• Average heart beat is approx. 75 beats /minute
• Cardiac output is 70x75 5,250, this tells
  Dr.s how much cardiac reserve a pt has

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Heart Rate

• Is the number of times the heart beats per minute
  our book states 75 beats/minute

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Preload-contractility-afterload

• Preload is the stretching of muscles fibers in
  the ventricles, this occurs at end diastole. The
  more blood volume, the greater the fibers stretch
• Contractility refers to the ability of the
  myocardium to contract normally
• Afterload refers to the pressure that the
  ventricles must generate to overcome the higher
  pressure in the aorta to get the blood out of the
  heart

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Blood Flow

• As the blood makes its way through the vascular
  system, it travels through 5 distinct types of
  blood vessels
• 1. Arteries
• 2. Arterioles
• 3. Capillaries
• 4. Venules
• 5. Veins

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Arteries

• Have thick muscular walls to accommodate the flow
  of blood at high speeds and pressures
• Arteries take oxygenated blood away from the heart

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Arterioles

• These have thinner walls than arteries
• Arterioles constrict or dilate to control blood
  flow to the capillaries

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Capillaries

• Are microscopic, their walls are composed of only
  a single layer of endothelial cells
• Capillaries receive blood from the arterioles

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Venules

• Venules gather blood from the capillaries
• A venules wall is thinner than that of arteries

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Veins

• Have thinner walls than arteries
• Veins bring de-oxygenated blood back to the heart

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How many miles does our blood circulate through

• 60,000 miles of arteries, arterioles,
  capillaries, veins and venules, keep blood
  circulating to and from every functioning cell in
  the body

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The Hearts Conduction System

• Electrical energy stimulates the heart muscle to
  contract, this allows blood to move throughout
  the body

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Internal pacemaker (SA NODE)

• The conduction system of the heart contains
  pacemaker cells which do 3 things
• 1. Automaticity known as the sinoatrial (SA)
  node, located in the upper wall of the Right
  atrium
• 2. Conductivity
• 3. Contractility

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SA Node

• The SA node contains K receptors just where the
  blood enters the superior vena cave
• When the K filled blood rushes past the SA node,
  it excites the Right atrium
• It then sends an electrical impulse to the AV
  node and sends the impulse down to the Bundle of
  HIS, down to the perkinje fibers and back up the
  heart

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AV Node (atrioventricular node)

• This node is located in the inter-atrial septum
  at the bottom of the right atrium

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The Bundle of His (hiss)

• Is an atrioventricular bundle
• This is located at the top of the
  interventricular septum

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Purkinje Fibers

• These conduction myofibers are located beneath
  the ventricles of the heart. These are at the
  bottom near the apex
• These form the last part of the cardiac
  conduction system

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Electricity through the heart

• 1) SA node
• 2) AV node
• 3) Bundle of His
• 4) L. Bundle Branch R. Bundle branch
• 5) Perkinje Fibers

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Intercalated Discs

• These are special membranes between the cells of
  the heart that allow for rapid flow of impulses
  throughout the heart muscle

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The Conduction Pathway

• The order in which impulses travel through the
  heart is as follows
• 1. Sinoatrial (SA) Node
• 2. Atria contracts
• 3. Atrioventricular (AV) Node is stimulated
• 4. Bundle of His
• 5. Purkinje Fibers
• 6. Stimulates the ventricles

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EKG

• Checks the rhythm of the heart muscle by looking
  at the wave it makes
• A normal rhythm is called Normal Sinus Rhythm

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Normal Sinus rhythm
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Atrial Fibrillation
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Ventricular Fibrillation
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Control of the Heart Rate

• Influences that allow the heart to meet changing
  needs rapidly
• 1. Autonomic nervous system (ANS)
• 2. Sympathetic nervous system (SNS)
• 3. Cranial nerve X vagus nerve, it slows the
  heart by acting on the SA and AV node

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Variations in Heart Rates

• Bradycardia slow heart rate lt 60 beats/minute.
  During rest and sleep, can fall even lower
• Tachycardia fast heart rate gt100 beats/minute.
  Normal during exercise or stress or occurs under
  abnormal circumstances
• Sinus arrhythmia is a regular variation in
  heart rate d/t changes in the rate and depth of
  breathing
• Premature Beat a heart beat comes too early,
  occurs when one takes in caffeine, nicotine or
  r/t stress or heart disease PVC- premature
  ventricular contraction

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Murmur

• Usually d/t faulty action of a valve
• If a valve fails to close tightly and blood leaks
  back, a murmur is heard
• OR
• If there is narrowing of a valve opening, youll
  have a murmur

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Heart Disease

• Any layer of the heart can become inflamed
• Endocarditis endocardium
• Myocarditis myocardium
• Pericarditis pericardium
• These inflammatory disease are often d/t
  infection
• Heart Disease is the most common cause of death
  in the U.S.

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Agents that cause heart disease

• Congenital Heart disease born with it
• Rheumatic Heart disease starts with rheumatic
  fever as a child
• Coronary artery disease involves the walls of
  the vessels that supply the heart with blood
• Congestive Heart Failure deterioration of heart
  tissues, usually r/t HTN

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Congenital Heart Disease

• Often results from fetal developmental defects,
  these include
• Atrial Septal defect
• Patent (open) ductus arteriosus (PDA) the
  vessel that connects the pulomonary artery to the
  aorta should close after birth
• Ventricular Septal defect (VSD) hole in the
  septum
• Coarctation of the aorta narrowing of the aorta
• Tetrology of Fallot (TET) causes a blue baby

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Shunt Blood from Right Atrium to Left Atrium
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Patent foramen ovale
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• Shunt Blood from Right Atrium to Left Atrium

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PDA
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Tetrology of Fallot (TET)

• Tetralogy of Fallot is rare, but it is the most
  common form of cyanotic congenital heart disease

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Tetralogy of Fallot is a birth defect of the
heart consisting of four abnormalities that
results in insufficiently oxygenated blood pumped
to the body. At birth, infants may not show the
signs of the cyanosis but later may develop
episodes of bluish skin from crying or feeding
called "Tet spells".
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Ductus Venosus Shunt blood from Liver
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Rheumatic fever and heart disease

• Streptococci release toxins during infection
• The antibodies that attack the strep, attack the
  valves
• Mitral valve on Left becomes inflamed
• The valve cusps thicken and harden
• Pulmonary congestion occurs

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Coronary Artery Disease

• The coronary arteries undergo degenerative
  changes over time
• The vessels narrow d/t soft plaque
  (athersclerosis) and overtime, crack and harden
  (arteriosclerosis)
• This narrowing causes blood to not flow well

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Ischemia

• A lack of blood supply to tissues
• Coronary arteries get clogged up, blood cant
  flow well, lack of O2 ischemia, causes death to
  tissues

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M.I. myocardial infarction

• When complete closure of a vessel occurs, the
  muscle dies
• Infarct is when the muscle dies

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Angina Pectoris

• This is your warning that there is blockage
• This is the calm before the storm
• The pain before the heart attack
• Meds are given to help open up vessels
• Nitroglycerine used to dilate coronary arteries
  to improve circulation to the heart
• Given sub-lingual (S.L.) take 1 tab every 5
  minutes until pain is gone, take no more than 3
  tabs/15 minutes, can cause low BP

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Heres how it goes

• Eat bad food high cholesterol
  arteriosclerosisischemia and low blood
  flowangina which is paininfarct which is when
  there has been such low blood flow, the heart
  muscle actually dies this term is M.I.

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Nitroglycerine

• Must be kept in a dark
• bottle away from light
• and air
• Pills will tingle in the mouth when they are
  taken and when they are not expired, if no
  tingling occurs, replacement pills need to be
  purchased, these are not fresh pills
• Pts should replace nitro pills approx. Q 3 months

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Heart Failure CHF
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Broken Left Ventriclewhat happens?

• Blood cannot exit the aorta and go to the body
  d/t left ventricle muscle decreased
• It backs up into the Left Atrium, and sits there
• When stasis occurs, water sits there but the
  stuff in the vessels is unequal, water moves
  out into the lungs to try and equal itself and
  now water goes to the lungs

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Fluid Collection

• Left-sided heart pulmonary edema
• Pt has S.O.B., dyspnea, pink frothy sputum
• Right sided heart edema to neck veins, arms,
  hands, fingers, belly, legs, and feet

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Pink Frothy Sputum
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What to do for CHF

• The pump is not strong and is causing a back up
  of blood..
• You need a better pump
• Cant get a transplant
• What else can you do?????
• Meds

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Digoxin (Lanoxin)

• Cardiotonic
• Increases cardiac strength and slows HR
• Side effects bradycardia, anorexia
• There is a narrow margin of safety between
  therapeutic and toxic effects
• Toxic effects visual disturbances such as seeing
  green and yellow halos, confusion
• Labs must be done to check the Dig. levels

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Lasix (furosemide)

• Diureticcalled a loop diuretic because of where
  it works, in the Loop of Henle in the nephron in
  the kidney
• Increases urine output
• Side effects dehydration, low BP, decrease K

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Potassium Replacement (K) for pts who are
hypokalemic low K

• K-Dur
• Taken P.O.
• Side effects are arrhythmias
• Normal K level 3.5-5.0

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Today.

• Drs are adding ACE Inhibitors Diuretics for the
  treatment of CHF
• Which sided heart failure is likely to cause the
  death of a patient? RIGHT or LEFT

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The Heart in the Elderly

• The heart ages over time
• Decrease in contraction and strength
• Valves become less flexible
• Murmurs develop
• Cardiac output decreases
• They get abnormal rhythms
• They have heart block

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Prevention of Heart Disease

• Risk factors that CANNOT be modified
• Age
• Gender
• Heredity
• Body type
• Risk factors that CAN be modified
• Smoking physical activity
• Weight/diet BP/Disease
• Physical activity Diabetes, gout

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Heart Studies

• Stethoscope
• Electrocardiogram (EKG) or (ECG)
• Catheterization
• Fluoroscope
• Echocardiography (ultrasound of heart)

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Treatment of Heart Disease

• Medical approaches pacemakers
• Surgical approaches bi-pass
• Combines approaches

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Clubbing d/t chronic low levels of O2
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Medications

• Digitalis
• Nitroglycerine
• Beta-blockers Metoprolol
• Antiarrhythmic agents
• Slow calcium channel blockers
• Anticoagulants
• Aspirin

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ACE inhibitors

• Most info. Is at RN level however
• Liver makes angiotensinogen and sends it out
• Kidney makes renin and sends it out
• Together, those 2 convert to angiotensin I
• Then it turns into angiotensin II
• This sparks the sympathetic nervous system
• Then the adrenals get stimulated to send ADH,
  where theres salt there water
• All this is in an effort to raise BP

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ACE inhibitor

• Puts a stop to the conversion of angiotensin I
  into angiotensin IInow you wont have high BP

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Calcium Channel Blocker(slow calcium)

• These work by disrupting the flow of calcium into
  the heart
• It slows the contractions
• Norvasc (amlodipine)
• Cardizem (diltiazem)
• Procardia (nifedipine)
• Calan (verapamil)

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BP Pulse
ACE inhibitors ? ?
Beta blockers ? ?
Calcium Channel blockers ? ?
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Correction of arrhythmias

• Application of pace maker
• It is at a set rate to fire when HR is below what
  Dr. sets it at.
• Implantable cardioverter-defibrillator (ICD)

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Heart Surgery

• Coronary Artery Bypass
• Angioplasty using a balloon to dilate the
  clogged up vessel
• Valve replacement
• Surgical transplant of heart or lungs
• Artificial heart

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Echocardiography(AV)
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Atherosclerosis (AV)
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Stress Test (AV)
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Cardiac Cath (AV)
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Dyes

• Cardiac caths are done using dye
• If your pt is allergic to iodine OR shellfish,
  they CANNOT receive this dye
• It will cause a severe allergy and even death

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Angioplasty (AV)
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Angioplasty-scraping (AV)
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Angioplasty with laser (AV)
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Stent (AV)
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Myocardial Infarction
Ischemia caused Infarction
Angina Pectoralis is a symptom of Ischemia
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Thrombolytics (AV)
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Electrocardiography
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How to care for a pt who is having an M.I.

• Administer nitroglycerine to help open the
  coronary arteries
• Give O2
• Give morphine to relieve the pain
• Provide a calm environment
• Administer aspirin if the pt can take P.O.

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The End