Download Trends February 2016 Cardiac Anatomy [Compatibility Mode]

2/12/2016
The following information is not intended for
the EMT to gain enough information to
interpret any cardiac rhythm
It is provided to help understand the cardiac
muscle, the electrical system and the
mechanical cells of the heart
Remember to follow state protocol and your
medical director’s guidelines
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Cardiovascular Anatomy
More than 60 million Americans have some
form of cardiovascular disease.
Cardiac Physiology
◦ Coronary heart disease (CHD), a type of CVD, is
the single largest killer of Americans.
Electrocardiographic Monitoring
Sudden death from CHD is often
preventable.
◦ Prompt recognition of symptoms
◦ Quality health care
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Public education about CHD
◦ Risk factors
◦ Recognition of signs and symptoms of heart
attack
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
1
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Tissue Layers
https://youtu.be/oHMmtqKgs50
◦ Endocardium
◦ Myocardium
◦ Pericardium
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Chambers
Valves
◦ Atria
◦ Atrioventricular
Valves
Superior chambers
◦ Ventricles
Inferior chambers
Tricuspid valve
Mitral valve
◦ Semilunar Valves
◦ Septum
Interatrial
Interventricular
Aortic valve
Pulmonic valve
◦ Papillary Muscles
◦ Chordae Tendonae
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Coronary Circulation
Coronary Circulation (cont.)
◦ Coronary arteries originate in the aorta, just
above the leaflets of the aortic valve.
◦ Left Coronary Artery
◦ Right Coronary Artery
Supplies the left ventricle, the interventricular septum,
part of the right ventricle, and the heart’s conduction
system.
2 branches
Supplies a portion of the right atrium and right ventricle
and part of the conduction system
2 branches
Posterior descending
Marginal branch
◦ Coronary vessels receive blood during diastole
Anterior descending
Circumflex
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
2
2/12/2016
Coronary Circulation (cont.)
◦ Blood drains via:
Anterior great cardiac vein
Lateral marginal veins
◦ Veins empty into the coronary sinus.
◦ Anastamoses among the various branches of the
coronary arteries allow collateral circulation.
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Arterial system
Venous system
◦ Carries oxygenated blood from the heart
◦ Transports blood from the peripheral tissues
back to the heart
◦ Functions under low pressure
Blood is under high pressure
◦ Smaller structures called arterioles, control blood
flow to various organs by their degree of
resistance
Terminate at capillaries where exchange takes place
Muscular contraction and valves
◦ Blood enters the venous system through the
capillaries
Venules
Veins
Venae cava
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
The Cardiac Cycle
◦ Diastole
Relaxation/filling phase
◦ Systole
Ejection fraction
Normally, 2/3 of ventricular volume is ejected
◦ Stroke volume
Amount of blood ejected in 1 cycle
Dependent on
Preload
Cardiac contractility
Afterload
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
3
2/12/2016
The Cardiac Cycle
◦ Starling’s Law
The more the myocardial muscle is stretched, the greater
its force of contraction will be.
The more diastolic volume, the greater the cardiac
output.
◦ Cardiac Output
Volume of blood that the heart pumps in 1 minute
Stroke volume (mL)  heart rate (bpm) = cardiac output
(mL/min).
Nervous Control
of the Heart
◦ Autonomic Control
of the Heart
Sympathetic
Parasympathetic
◦ Chronotropy
◦ Inotropy
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
The Heart as an Endocrine Organ
Role of Electrolytes
◦ Hormones are secreted by the heart in response
to hemodynamic stress
◦ Effects
◦ Electrolytes that affect cardiac function include
Diuresis (loss of water), natriuresis (loss of sodium), and
vasodilation
Sodium (Na+)
Plays a major role in depolarizing (contraction)
Calcium (Ca++)
Takes part in myocardial depolarization and myocardial
contraction
Potassium (K+)
Influences repolarization (resetting for contraction)
Chloride (Cl–)
Magnesium (Mg++)
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
The heart has two syncytia:
◦ Atrial syncytium
Contracts from superior to inferior
◦ Ventricular syncytium
Contracts from inferior to superior
The only way an impulse can be conducted
from the atria to the ventricles is through
the atrioventricular (AV) bundle.
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
4
2/12/2016
Each component of the conductive system
has its own intrinsic rate of self-excitation.
◦ SA node = 60–100 beats per minute
◦ AV node = 40–60 beats per minute
◦ Purkinje system = 15–40 beats per minute
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Electrocardiogram (ECG) is a graphic record
of the heart’s electrical activity.
◦ Tells you nothing about the heart’s pumping
ability, which you must evaluate by pulse and
blood pressure.
The body acts as a giant conductor of
electricity.
◦ The heart is its largest generator
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Electrical Impulses
◦ Positive impulses
Deflect upward
◦ Negative impulses
Deflect downward
◦ The isoelectric line
Absence of deflection
Artifact
Electrodes on the skin can detect the total
electrical activity within the heart.
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
ECG Leads
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Lead Systems and Heart Surfaces
◦ Bipolar (Limb)
Einthoven’s Triangle
Leads I, II, III
Provide only one view of the
heart
◦ Augmented (Unipolar)
aVR, aVL, aVF
◦ Precordial
V1 – V6
Measure electrical cardiac
activity on a horizontal axis
Help in viewing the left
ventricle and septum
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
5
2/12/2016
Routine Monitoring
◦ Routine ECG monitoring generally uses only
one lead
◦ Most common monitoring leads are either lead
II or the modified chest lead 1 (MCL1)
◦ Einthoven’s triangle offers a basis for placing
the leads
Single lead cannot
show:
Information from a
single lead shows:
◦ Presence of an infarct
◦ Axis deviation or
chamber
enlargement
◦ Right-to-left
differences in
conduction
◦ Quality or presence
of pumping action
◦ Rate
◦ Regularity
◦ Time to conduct an
impulse
Place the electrodes on the chest wall
Lead placement
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Relationship of
the ECG to
Electrical Events
in the Heart
◦ ECG Components
P Wave
QRS Complex
T Wave
U Wave
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Tachycardia
◦ Etiology
May be precipitated by stress, overexertion, smoking,
caffeine or an irritated area of the heart muscle
◦ Clinical Significance
May be tolerated well by healthy patients for short
periods
Marked reduction in cardiac output can precipitate
angina, hypotension, or congestive heart failure
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bradycardia
Rules of Interpretation
◦ Etiology
Increased vagal tone, pathological slow SA node
discharge, heart block, intrinsic disease
◦ Clinical Significance
Ventricular Escape Complexes
and Rhythms
Rate
Decreased cardiac output
Rhythm
◦ Treatment
Keep supine to help brain perfusion
Tier with ALS if possible
Be prepared to start CPR if patient still is unconscious
Pacemaker
Site
P Waves
PRI
QRS
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
15–40
Escape complex, irregular;
escape rhythm, Regular
Ventricle
None
None
>0.12 seconds, bizarre
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
6
2/12/2016
Rules of Interpretation
Ventricular Fibrillation
Rate
Rhythm
No organized
rhythm
No organized
rhythm
Pacemaker
Site
Numerous
ventricular foci
P Waves
Usually absent
PRI
None
QRS
None
Ventricular Fibrillation
◦ Etiology
Wide variety of causes, often resulting from advanced
coronary artery disease
◦ Clinical Significance
Lethal dysrhythmia with no cardiac output and no
organized electrical pattern
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Ventricular Fibrillation
Rules of Interpretation
◦ Treatment
Initiate CPR
Defibrillate with 360 J (or biphasic equivalent)
Control the airway and establish IV access
◦ ALS
Administer epinephrine 1:10,000 every 3–5 minutes
Consider 40 IU Vasopressin IV (one time only)
Consider second-line drugs
Amiodarone
Lidocaine
Artificial Pacemaker
Varies with
pacemaker
Rate
Rhythm
Pacemaker
Site
P Waves
PRI
Provide continuous compressions
QRS
May be regular or
irregular
Depends upon
electrode placement
None produced by
ventricular pacemakers;
pacemaker spike
If present, varies
>0.12 seconds,
bizarre
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Artificial Pacemaker Rhythm
Artificial Pacemaker Rhythm
◦ Etiology
◦ Problems with Pacemakers
Single vs. dual chamber pacemakers
Fixed-rate vs. demand pacemakers
◦ Clinical Significance
Used in patients with a chronic high-grade heart block,
sick sinus syndrome, or severe symptomatic bradycardia
Battery failure
“Runaway” pacers
Displaced leads
◦ Management Considerations
Identify patients with pacemakers
Treat the patient
◦ Use of a Magnet
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
7
2/12/2016
Bledsoe et al., Paramedic Care: Principles & Practice, Volume 3: Medical Emergencies, 3rd Ed.
© 2009 by Pearson Education, Inc. Upper Saddle River, NJ
8