Coronary Artery Disease
Complications
Cardiac
Arrhythmias/Dysrhythmias
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Conduction System
 Four Properties of Cardiac Tissue
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Automaticity – ability to initiate an impulse
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Contractility – ability to respond mechanically to an impulse
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Conductivity – ability to transmit an impulse along a membrane in an orderly manner
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Excitability – ability to be electrically stimulated

Cardiac Conduction
System
Specialized neuromuscular tissue
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PR Interval:
 SA Node – upper R atrium through Bachman’s
Bundle
 AV Node – internodal pathway
 Bundle of His
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QRS Complex:
 Right and Left Bundle Branches
 Purkinje Fibers

Cardiac Conduction

Cardiac Monitoring
PQRS Complex

Cardiac Action Potential

Calculating Heart Rate
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EKG paper is a grid where time is measured along the horizontal axis.
Each small square is 1 mm in length and represents 0.04 seconds.
Each larger square is 5 mm in length and represents 0.2 seconds.
Voltage is measured along the vertical axis - 10 mm is equal to 1mV in voltage.
Heart rate can be easily calculated from the EKG strip:
Heart rate can be easily calculated from the EKG strip:
• When the rhythm is regular:
• the heart rate is 300 divided by the number of large squares between the QRS complexes.
• e.g., if there are 4 large squares between regular QRS complexes, the heart rate is 75 (300/4=75).
• The second method can be used with an irregular rhythm to estimate the rate:
• Count the number of R waves in a 6 second strip and multiply by 10.
• e.g., if there are 7 R waves in a 6 second strip, the heart rate is 70 (7x10=70).

Cardiac Monitoring
Cardiac Rate

Cardiac Monitoring
Amplitude / Duration

12 Lead EKG

EKG Leads

12-Lead EKG

Reciprocal EKG Changes

Cardiac Monitoring
Chest Lead Placement

Cardiac Monitoring- MCL

Cardiac Monitoring
Normal Sinus Rhythm

Cardiac Monitoring
PQRS Complex

Cardiac Monitoring
Cardiac Rhythm Analysis
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Analyze the P waves – rate/rhythm
Analyze the QRS complexes – rate/rhythm
Determine the heart rate
Measure the PR Interval
Measure the QRS duration
Interpret the rhythm
Clinical significance? Hemodynamic status?
Appropriate Tx

Cardiac Monitoring
Normal Sinus Rhythm

Cardiac Monitoring
Normal Sinus Rhythm

EKG / Heart Sounds

Cardiac Monitoring
Normal Sinus Rhythm
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Atrial & Ventricular rhythms: regular
Rate: 60-100 beats/min
P waves: present consistent configuration, one P wave prior to each QRS complex
PR interval: .12 – .20 sec and constant
QRS duration: -.04 to .10 sec and constant

Cardiac Monitoring
Sinus Dysrhythmias

Cardiac Monitoring
Sinus Bradycardia
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SA Node discharges < 60 beats/ min
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Etiology: >parasympathetic stimulation / vagus nerve
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Assess: LOC, Orientation, VS, PO, pain, escaped ventricular ectopy
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Tx: If patient is symptomatic – raise legs up, move patient, Atropine – ACLS Bradycardia

Cardiac Monitoring
Sinus Tachycardia Sinus Bradycardia

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Cardiac Monitoring
Sinus Tachycardia
SA Node discharge > 100 beats/ min
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Etiology: Sympathetic stimulation – normal or abnormal response
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Tx: Treat underlying cause
 Cardiac Supply Problems
 Cardiac Demand Problems
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E.g., hypovolemia, hypoxemia, anxiety, pain, anemia, angina
 Regular Narrow QRS - Adenosine

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Sustained
Tachy / Brady Dysrhythmias
Chest discomfort, or pain, radiation to jaw, back, shoulder or upper arm
Restlessness, anxiety, nervousness
Dizziness, syncope
Change in pulse strength, rate, rhythm
Pulse deficit
Shortness of breath, dyspnea
Tachypnea, Orthopnea
Pulmonary rales
S3 or S4 heart sounds
Jugular vein distention
Weakness, fatigue
Pale, cool skin, diaphoresis
Nausea, vomiting
Decreased urine output
Hypotension

Cardiac Monitoring
PSVT

Cardiac Monitoring
Paroxysmal Supraventricular
Narrow QRS Tachycardia (PSVT)
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SA Node rate 100-280 beats/min - M ean 170 beats/min
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Etiology: Pre-excitation syndrome, e.g., Wolff-
Parkinson White (WPW) Syndrome
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Assess: Weakness, fatigue, chest pain, chest wall pain, hypotension, dyspnea, nervousness
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Tx: Valsalva maneuvers: bearing down, gagging, ocular pressure, vomiting, carotid sinus massage,
 Meds: Adenosine

Cardiac Monitoring
Interference

Cardiac Monitoring
Atrial Flutter / Fibrillation

Cardiac Monitoring
Atrial Flutter / Fibrillation

Cardiac Monitoring
Atrial Fibrillation
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Most Common dysrhythmia in the US
Multiple rapid impulses from many atrial foci, rate of 350-600/min—depolarize the atrial in a disorganized and chaotic manner – atrial quiver
Results:
 No P waves
 No atrial contracts
 No atrial kick
 Irregular ventricular response

Cardiac Monitoring
Atrial Fibrillation
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Etiology: MI, RHD with Mitral Stenosis,
CHF, COPD, Cardiomyopathy,
Hyperthyroidism, Pulmonary emboli, WPW
Syndrome, Congenital heart disease
** Mural Thrombi – increased risk for pulmonary & systemic thromboemboli to brain & periphery
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Assess: VS, PO, Pulse Deficit, chest pain, syncope, hypotension
 Symptoms worsen with increased ventricular response

Cardiac Monitoring
Atrial Fibrillation
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Tx:
 TEE – Trans-esophageal echocardiogram
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Identifies thrombi on valves
 Medications to decrease the ventricular response - Metoprolol (Lopressor)
 Oxygen
 Prophylactic anticoagulation
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Lovenox - Coumadin – long term
 Cardioversion

Cardiac Monitoring
Atrial Fibrillation
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Tx:
 Medications to decrease the ventricular response
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Narrow QRS irreg rhythm–diltiazem; beta-blockers
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Wide QRS reg rhythm – amiodarone
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Wide QRS irreg rhythm – digoxin, diltiazem, verapermil, amiodarone
 Oxygen
 Prophylactic anticoagulation
 Cardioversion

Cardiac Monitoring
Atrial Fibrillation
Cardioversion
 Synchronized countershock
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50 – 100 Joules
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Avoids delivering shock during repolarization
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Patent intravenous line
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Patient sedated – Versed
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Oxygenation
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ABC
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Assess: VS, PO, Monitor cardiac rate - rhythm
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Administer antidysrhythmic medication

Cardiac Monitoring
Junctional Escape Rhythm

Cardiac Monitoring
Junctional Escape Rhythm
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Impulse generated from AV nodal cells at the AV Junction
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Escape pacemaker
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Rate 40-60 beats/ min
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Transient
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Assess: Patient hemodynamic stability

Cardiac Monitoring
Premature Ventricular
Contractions

Cardiac Monitoring
NSR – V. Tach – V. Fibrillation

Cardiac Monitoring
Ventricular Tachycardia

Cardiac Monitoring
Ventricular Dysrhythmias

Cardiac Monitoring
Premature Ventricular
Contractions

Cardiac Monitoring
Premature Ventricular
Contractions (PVCs)_
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Early ventricular complexes
 Followed by compensatory pause
 Fit between two NSR beats - interpolated
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Unifocal, multifocal, couplet, triplets, bigeminy, trigeminy, quadrigeminy
 3+ = ventricular tachycardia
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Etiology: myocardial ischemia, <K+, CHF, metabolic acidosis, airway obstruction

Cardiac Monitoring
Premature Ventricular
Contractions (PVCs/
Ventricular Tachycardia with Pulse
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Assess: LOC, hemodynamic status-continuous cardiac monitoring of rhythm & rate, VS, PO, peripheral perfusion
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Tx: Underlying cause + Oxygen,
Amiodarone IV bolus / Infusion

V. Tachycardia/V. Fibrillation
Pulseless
 TX: CPR BLS - Airway, Breathing, Circulation
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Shockable Rhythm VT/VF: Defibrillate – 120-200 Joules
 CPR x 5 cycles
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Check rhythm – shockable?
Defibrillate (biphasic 200 J / monophasic 360 J
 Resume CPR
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Epinephine 1 mg IV (repeat q3-5 mins) / Vasopressin
 CPR x 5 cycles
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Check rhythm – shockable?
Defibrillate (biphasic 200 J / monophasic 360 J
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Resume CPR
 Antiarrhythmics: amiodarone/lidocaine
 Magnesium – torsades de pointes

Cardiac Monitoring
V Fib - Agonal Rhythm

Common Causes of
Dysrhythmias
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Cardiac
 Accessory pathways, conduction defects, congestive heart failure, left ventricular hypertrophy, myocardial cell degeneration, myocardial infarction
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Other Conditions
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Acid-base imbalances, alcohol, coffee, tea, tobacco, connective tissue disorders, drug effects or toxicity, electric shock, electrolyte imbalances, emotional crisis, hypoxia, shock, metabolic disorders (e.g. thyroid), near-drowning, poisoning

Cardiac Monitoring
Heart Block
1 st , 2 nd Types I & II

Cardiac Monitoring
Heart Blocks

Cardiac Monitoring
First Degree AV Block
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First Degree AV Block: all sinus impulses eventually reach ventricles
 Prolonged PR Interval >.20
 Etiology: AV nodal ischemia – right coronary artery (inferior MI); hypokalemia, increased beta-blockers or calcium channel blockers, narcotics, excessive vagal stimulation
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Assess: Hemodynamically stable
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Tx: withhold offending medication; oxygen; atropine, notify physician; observe

Cardiac Monitoring
Second Degree AV Block
Mobitz Type I - Wenckebach
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Each impulse takes progressively longer
 Progressive lengthening of PR Interval
 Followed by a dropped beat (missing QRS complex) & a pause
 May need temporary transvenous pacer
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Etiology: Often transient following anterior / inferior wall
MI – may revert to 1 st Degree AV Block
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Assess: Hemodynamic stability
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Tx: Atropine / May require Temporary Transcutaneous
Pacemaker / CPR / ACLS Protocol

Cardiac Monitoring
Second Degree AV Block Mobitz
Type I - Wenckebach

Cardiac Monitoring
Second Degree AV Block
Mobitz Type II
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Etiology: Infranodal block in one of the bundle branches
 Dropped QRS complex without progressive lengthening of
PR interval
 P wave with no QRS complex following
 Random block
 May progress to 3 rd Degree AV Block – need for permanent pacer
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Assess: Hemodynamic stability
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Tx: Atropine / Transcutaneous pacemaker / CPR /
ACLS Protocol

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Cardiac Monitoring
Third Degree AV Block
No sinus impulses conduct to the ventricles
AV dissociation – rate: 40/min
PR interval not constant – no relationship with P and
QRS complex
Ventricular pacemaker – may abruptly fail causing ventricular asystole
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Etiology: Anterior Wall MI; hypoxemia, electrolyte disturbances, cardiac surgery

Cardiac Monitoring
Third Degree AV Block
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Assess: Hemodynamic stability
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Tx:
 CPR
 ACLS Protocol
 Pacemaker

Cardiac Monitoring
Paced Rhythm

Cardiac Monitoring
Paced Rhythm

Indications for
Permanent Pacemaker
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Chronic atrial fibrillation with slow ventricular response
Fibrosis or sclerotic changes of the cardiac conduction system
Hypersensitive carotid sinus syndrome
Sick sinus syndrome
Sinus node dysfunction
Tachydysrhythmias
Third-degree AV block

Cardiac Monitoring
Ventricular Standstill
Pulseless Asystole
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CPR
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ACLS Protocol
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Tx: Atropine, Epinephrine, dopamine

Pulseless Asystole
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Shockable Rhythm? No – BLS/CPR
Epinephrine 1 mg IV (may repeat q3-5 mins)
(or one dose of Vasopressin)
Atropine
5 cycles of CPR
Shockable rhythm? NO - CPR
Yes – Pulseless V Fib

Cardiac Dysrhythmias
 ASSESS THE PATIENT
 Treat the underlying cause
 Support hemodynamically
 Emergency Cardiac Medication
 CPR
 Transcutaneous/Transvenous pacemaker
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Information and emotional support to patient & family

New Cardiac Advances
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Implantable cardioverter – defibrillator
(AICD)
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Automatic external defibrillator (AED)
 ABCD
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Cardiac Ablation Therapy
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BLS
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ACLS