Transcript File - Respiratory Therapy Files

Lecture Notes
Chapter 17
Functional Anatomy of
the Cardiovascular
System
Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.
1
Gross Anatomy of the Heart
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Lies in mediastinum behind sternum
Apex points to the left
Point of maximal impact (PMI)
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The apical beat
5th Intercostal space
at mid-clavicular line
Causes of PMI shift
• Left Sided Pneumothorax
• Pg. 301
ConceptQuestion
17-1
Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.
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Clinical Focus 17-1
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32 y.o. man. Severe chest wall injury sustained in
automobile accident. Conscious, anxious, c/o
dyspnea and chest pain. Distending neck veins,
tachycardia; systolic blood pressure of 90mmHg.
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Read the discussion (pg. 304)
1. The patient exhibits signs of ________________
2. What is this disease?
3. Cause of distended neck veins?
4. Cause of increased HR?
5. Cause of low systolic pressure?
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Pericardium
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Loose-fitting membranous sac
Parietal vs. visceral pericardium (epicardium)
Pg. 302
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Parietal = outter sac
Visceral (epicardium) = inner
The fluid in between = pericardial fluid… Acts
as lubrication allowing for smoother,
frictionless movement as the heart beats.
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Anatomy of the Heart
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Heart wall
 Epicardium, Myocardium, Endocardium
 Myocardium =
Heart chambers and valves
 2 atria and 2 ventricles
 RA receives deoxygenated blood from
superior vena cava, inferior vena cava
 LA receives oxygenated blood from
pulmonary veins
• Greater muscle mass than the right
ventricle
Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.
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Anatomy of the Heart
Fig. 17-3
Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.
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Anatomy of the Heart

Heart chambers and valves
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Atrial-ventricular valves
• Tricuspid = Right or Left side? ConceptQuestion
17-2
• Mitral = Right or Left side?
• PURPOSE = prevent back flow of blood during ventricle
contractions

Ventricular outflow
pg 302
• Right Ventricle Pumps through
_________________
• Left Ventricle Pumps through
__________________
• Prevents backflow of blood into the ventricles
during ventricle relaxation
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Clinical Focus 17-3
Mitral Valve Stenosis
Person with Severe Mitral Valve Stenosis
requires oxygen and shows signs of
pulmonary edema.
What is Pulmonary Edema?
What is the connection of a cardiac problem
leading to a pulmonary problem?
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Clinical Focus 17-2
Ventricular Septal Defect (VSD)
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What is it?
Mixing of blood from the two chambers
Treatment?
If patient is symptomatic (SOB), it will need
surgical correction.
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
Coronary Circulation
Though the heart pumps blood, it also
receives oxygenated blood to sustain itself
Coronary arteries
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Left and right coronaries
• 1. Right coronary is the dominant blood supplier
• 2. Originate immediately above aortic semilunar valve
• 3. “The heart relies almost exclusively on the two main
coronary arteries.” pg 305

In the heart, there is a lack of collateral circulation
if…
1. If blood flow is blocked = ischemia (tissue hypoxia) and
central chest pain (angina pectoris)
2. Myocardial infarction (MI) = heart muscle tissue death
MONA – Morphine, Oxygen, Nitroglycerin(vasodilator),
Asprin (prevent blood clot)
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Angina Pectoris
pg 306
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Aka Chest Pain
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Caused by: Coronary artery disease
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The pain is often felt beneath the sternum, in the left
arm, and in the neck
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“About 35% of all deaths in the United States are
caused by coronary artery disease” (CAD) pg. 306
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Coronary Circulation
Coronary veins
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pg 307
Flow parallel to arteries
Empty into right atrium (coronary sinus)
Oxygen requirement and blood flow
O2 extraction ≈70% (compare to 25% whole body)
  during exercise =  coronary flow
 O2 need governs coronary blood flow
Tachycardia is a response by the heart that it needs more
oxygen
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During exercise, because the heart can’t extract more oxygen from the
supply it’s getting… It needs to increase the blood flow by increasing the
heart rate and get oxygen more quickly.
If you give the patient oxygen, the heart rate will come back down.
Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.
13
Cardiac Conduction System
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pg 309
Specialized cardiac muscle tissue (not neurons)
Atria contract at last second (“atrial kick”) to complete
ventricular filling
Conduction
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Sinoatrial node (SA node) – Initiates Electrical Impulses. Travel
down to the AV Node.
Atrioventricular node (AV node) - Triggers initial contraction of
ventricles. Trigger travels down the AV bundle.
AV bundle aka “bundle of His”. The AV Bundle triggers down the
right and left bundle branches.
Bundle branches terminate into the Purkinje fibers
Purkinje fibers carry the electrical signal to the ventricles (apex of
the heart).
Ventricles receive signal and contract.
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Systole vs. Diastole
Diastole
Ventricle is relaxed and
fills with blood
Systole
Ventricle contracts
and ejects blood
Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.
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Example
In the _____________ phase, the mitral valve
and tricuspid valve is open, but the semilunar
valves remain closed.
A. Aortic
B. Diastolic
C. Systolic
D. Anacrotic
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Example
In the ______________ phase, the mitral
valve and tricuspid valve remain closed, but
the semilunar valves open.
A. Aortic
B. Diastolic
C. Systolic
D. Anacrotic
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Cardiac Conduction System
Time
“Stalls” for
Time
Fig. 17-10
Total Time From Electrical Signal To Ventricular Contraction =
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Cardiac Cycle
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Cardiac Cycle refers to a complete pumping cycle
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Ventricular filling PRELOAD
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Contraction (systole) and relaxation (diastole)
Beginning of Systole to the end of diastole = 0.8 seconds
80% passive + 20% atrial “kick”
80% is blood flowing from atria into ventricle
At the last moment, the atria kicks 20% more blood into the
ventricle to get the ventricle ready to pump
Ventricular emptying (contraction) AFTERLOAD
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Closure of the AV valves (1st heart sound)
Isovolumetric contraction (all valves closed)
Resistance to ejection = afterload
pg 316
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Volume of blood during cardiac cycle
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Ventricular filling PRELOAD
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Ventricular emptying (contraction) AFTER LOAD
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120 mL of blood total in this phase
“End-Diastolic” Volume
Normal amount of blood that is ejected = Stroke volume = 70
mL
How much is left in the ventricle?
• 50mL
• = “End-Systolic” Volume (Not the same as stroke volume)
Cycle repeats itself and the ventricle is filled back up
to 120mL in the preload phase.
If 70mL out of 120mL is ejected, what’s the
percentage of ejected blood?
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… this is known as…
EJECTION FRACTION
 Ejection fraction… Percentage is 58 or about
60%. (Normal ≈ 60%.)
 A low ejection fraction =
 Indicates = Less than 50%
indicates poor contractility and pumping failure
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On the flip side, during exercise, the ejection
fraction may increase up to 90%
pg 316
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From Previous Slide

Ventricular emptying (contraction) AFTER LOAD
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Normal amount of blood that is ejected = Stroke volume = 70 mL
How much is left in the ventricle?
• 50mL
• = “End-Systolic” Volume (Not the same as stroke volume)
Two ways to calculate Stroke Volume
1. Cardiac Output(mL) / HR
2. Preload – Afterload
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Determining Stroke Volume
Cardiac Output(mL) / HR
Example:
C.O = 5L/min
HR = 80/min
S.V. = ____ mL
Example:
C.O. = 3 L/min
HR = 120/min
S.V. = ______ mL
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Determining Stroke Volume
The following information is obtained:
HR 120/min
Preload volume 120mL
Afterload Volume 80mL
B/P 109/75mmHg
What is the stroke volume?
A. 210mL
B. 90mL
C. 50mL
 D. 40mL
Preload – Afterload (D)
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Summary
Which of the following is known as enddiastolic volume?
A. Afterload
B. Stroke Volume
C. Preload
D. Diastole
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C. Preload
Go back 5 slides ago
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Regulation of Pumping Activity
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Normally, the blood that comes in (Right Atrium) is
pumped out (Left Ventricle) at the same rate
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The heart has the ability to adapt to inflow
changes
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“Frank-Starling Mechanism”
The heart may lose its ability to adapt is the left
ventricle’s muscle has been over stretched
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Left Ventricle Fails
Blood backs up
Congestive Heart Failure
pg 314
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