Transcript The Heart Chapter 14 B&S

The Heart
Chapter 14
B&S
Traveling Through the Heart
Circulation
• The continuous one-way movement of the
blood
• The prime mover that propels blood
throughout the body is the heart
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)
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
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)
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 it’s own circulation
system (coronary circulation)
• Here, contraction of 1 fiber causes the whole
group to contract
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
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
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
Right Heart vs. Left Heart
• The human heart is really a double pump
• RIGHT SIDE
LEFT SIDE
• Pumps blood low in
• Oxygen to the lungs
pumps oxygenated blood
to the rest of the body
• The 2 sides are completely divided by a
septum - a septum is a wall dividing 2
cavities.
Septum of the heart
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
There are 4 chambers to the heart
•
•
•
•
1. Right Atrium
2. Right Ventricle
3. Left Atrium
4. Left Ventricle
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
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
Left Atrium
• Receives blood high in oxygenation
through the pulmonary vein right from the
lungs
Left Ventricle
• This chamber has the thickest
wall…why???
• It pumps oxygenated blood to all parts of
the body
Broken ventricles or premature
ventricular beats
• What will the patient look like?
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
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
Entrance & Exit Valves
• Entrance Valves
• Atrioventricular
• Tricuspid/bicuspid
valves
Exit Valves
semi-lunar
pulmonic &
aortic valves
Chordae tendineae
• Thread-like cords that connect the free
edges of the atrioventricular valves to the
papillary muscles in the ventricles
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
Blood flow through the heart
chambers
• Is called coronary circulation, it consists of:
• Right coronary arteries
• Left coronary arteries
• BIG PROBLEM WHEN CIRCULATION
STOPS>>>>>>>>>>>
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.
Blocked Coronary Artery
Coronary Artery Occlusion
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 thinwalled upper chambers called the atria, followed
by a contraction of the thick muscle of the lower
chambers called the ventricles. This is the lubdub sound
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)
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
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
Heart Rate
• Is the number of times the heart beats per
minute = our book states 75 beats/minute
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
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
Arteries
• Have thick muscular
walls to
accommodate the
flow of blood at high
speeds and pressures
• Arteries take
oxygenated blood
away from the heart
Arterioles
• These have thinner walls than arteries
• Arterioles constrict or dilate to control
blood flow to the capillaries
Capillaries
• Are microscopic, their walls are composed
of only a single layer of endothelial cells
• Capillaries receive blood from the
arterioles
Venules
• Venules gather blood from the capillaries
• A venule’s wall is thinner than that of
arteries
Veins
• Have thinner walls than arteries
• Veins bring de-oxygenated blood back to
the heart
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
The Heart’s Conduction System
• Electrical energy stimulates the heart
muscle to contract, this allows blood to
move throughout the body
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
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
AV Node (atrioventricular node)
• This node is located in the inter-atrial
septum at the bottom of the right atrium
The Bundle of His (hiss)
• Is an atrioventricular bundle
• This is located at the top of the
interventricular septum
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
Electricity through the heart
• 1) SA node
• 2) AV node
• 3) Bundle of His
• 4) L. Bundle Branch & R.
Bundle branch
• 5) Perkinje Fibers
Intercalated Discs
• These are special membranes between
the cells of the heart that allow for rapid
flow of impulses throughout the heart
muscle
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
EKG
• Checks the rhythm of the heart muscle by
looking at the wave it makes
• A normal rhythm is called Normal Sinus
Rhythm
Normal Sinus rhythm
Atrial Fibrillation
Ventricular Fibrillation
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
Variations in Heart Rates
• Bradycardia – slow heart rate < 60
beats/minute. During rest and sleep, can fall
even lower
• Tachycardia – fast heart rate >100
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
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,
you’ll have a murmur
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.
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
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
Shunt Blood from Right Atrium to Left
Atrium
Patent foramen ovale
Shunt Blood from Right Atrium to Left
Atrium
PDA
Tetrology of Fallot (TET)
• Tetralogy of Fallot is rare, but it is the most
common form of cyanotic congenital heart
disease
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".
Ductus Venosus
Shunt blood from
Liver
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
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
Ischemia
• A lack of blood supply to tissues
• Coronary arteries get clogged up, blood
can’t flow well, lack of O2 = ischemia,
causes death to tissues
M.I. – myocardial infarction
• When complete
closure of a vessel
occurs, the muscle
dies
• Infarct is when the
muscle dies
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
Here’s how it goes…
• Eat bad food = high cholesterol=
arteriosclerosis=ischemia and low blood
flow=angina which is pain=infarct which is
when there has been such low blood flow,
the heart muscle actually dies= this term is
M.I.
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
• Pt’s should replace nitro pills approx. Q 3
months
Heart Failure = CHF
Broken Left Ventricle
what 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
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
Pink Frothy Sputum
What to do for CHF
• The pump is not strong and is causing a
back up of blood…..
• You need a better pump
• Can’t get a transplant…
• What else can you do?????
• Meds
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
Lasix (furosemide)
• Diuretic…called 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+
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
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
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
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
Heart Studies
•
•
•
•
•
Stethoscope
Electrocardiogram (EKG) or (ECG)
Catheterization
Fluoroscope
Echocardiography (ultrasound of heart)
Treatment of Heart Disease
• Medical approaches –
pacemakers
• Surgical approaches
– bi-pass
• Combines
approaches
Clubbing d/t chronic low levels of O2
Medications
•
•
•
•
•
•
•
Digitalis
Nitroglycerine
Beta-blockers – Metoprolol
Antiarrhythmic agents
Slow calcium – channel blockers
Anticoagulants
Aspirin
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
ACE inhibitor
• Puts a stop to the conversion of
angiotensin I into angiotensin II…now you
won’t have high BP
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)
BP
Pulse
ACE inhibitors
↓
↑
Beta blockers
↓
↓
Calcium
Channel
blockers
↓
↓
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)
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
Echocardiography(AV)
Atherosclerosis (AV)
Stress Test (AV)
Cardiac Cath (AV)
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
Angioplasty (AV)
Angioplasty-scraping (AV)
Angioplasty with laser (AV)
Stent (AV)
Myocardial Infarction
Ischemia
caused
Infarction
Angina Pectoralis is a symptom of Ischemia
Thrombolytics (AV)
Electrocardiography
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.
The End