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Coronary Artery Disease Complications Cardiac Arrhythmias/Dysrhythmias Conduction System Four Properties of Cardiac Tissue Automaticity – ability to initiate an impulse Contractility – ability to respond mechanically to an impulse Conductivity – ability to transmit an impulse along a membrane in an orderly manner Excitability – ability to be electrically stimulated
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Cardiac Conduction System Specialized neuromuscular tissue PR Interval: SA Node – upper R atrium through Bachman’s Bundle AV Node – internodal pathway Bundle of His QRS Complex: Right and Left Bundle Branches Purkinje Fibers
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Cardiac Conduction
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Cardiac Monitoring PQRS Complex
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Cardiac Action Potential
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Calculating Heart Rate Calculating Heart Rate EKG paper is a grid where time is measured along the horizontal axis. 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 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. 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. 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: When the rhythm is regular: the heart rate is 300 divided by the number of large squares between the QRS complexes.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).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: 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.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).e.g., if there are 7 R waves in a 6 second strip, the heart rate is 70 (7x10=70).
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Cardiac Monitoring Cardiac Rate
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Cardiac Monitoring Amplitude / Duration
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12 Lead EKG
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EKG Leads
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12-Lead EKG
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Reciprocal EKG Changes
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Cardiac Monitoring Chest Lead Placement
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Cardiac Monitoring- MCL
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Cardiac Monitoring Normal Sinus Rhythm
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Cardiac Monitoring PQRS Complex
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Cardiac Monitoring Cardiac Rhythm Analysis 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
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Cardiac Monitoring Normal Sinus Rhythm
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EKG / Heart Sounds
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Cardiac Monitoring Normal Sinus Rhythm Atrial & Ventricular rhythms: regular Atrial & Ventricular rhythms: regular Rate: 60-100 beats/min Rate: 60-100 beats/min P waves: present consistent configuration, one P wave prior to each QRS complex P waves: present consistent configuration, one P wave prior to each QRS complex PR interval:.12 –.20 sec and constant PR interval:.12 –.20 sec and constant QRS duration: -.04 to.10 sec and constant QRS duration: -.04 to.10 sec and constant
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Cardiac Monitoring Sinus Dysrhythmias
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Cardiac Monitoring Sinus Bradycardia SA Node discharges < 60 beats/ min Etiology: >parasympathetic stimulation / vagus nerve Assess: LOC, Orientation, VS, PO, pain, escaped ventricular ectopy Tx: If patient is symptomatic – raise legs up, move patient, Atropine – ACLS Bradycardia
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Cardiac Monitoring Sinus Tachycardia Sinus Bradycardia
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Cardiac Monitoring Sinus Tachycardia SA Node discharge > 100 beats/ min Etiology: Sympathetic stimulation – normal or abnormal response Tx: Treat underlying cause Cardiac Supply Problems Cardiac Demand Problems 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
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Cardiac Monitoring PSVT
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Cardiac Monitoring Paroxysmal Supraventricular Narrow QRS Tachycardia (PSVT) SA Node rate 100-280 beats/min - M ean 170 beats/min Etiology: Pre-excitation syndrome, e.g., Wolff- Parkinson White (WPW) Syndrome Assess: Weakness, fatigue, chest pain, chest wall pain, hypotension, dyspnea, nervousness Tx: Valsalva maneuvers: bearing down, gagging, ocular pressure, vomiting, carotid sinus massage, Meds: Adenosine
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Cardiac Monitoring Interference
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Cardiac Monitoring Atrial Flutter / Fibrillation
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Cardiac Monitoring Atrial Fibrillation 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
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Cardiac Monitoring Atrial Fibrillation 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 Assess: VS, PO, Pulse Deficit, chest pain, syncope, hypotension Symptoms worsen with increased ventricular response
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Cardiac Monitoring Atrial Fibrillation Tx: TEE – Trans-esophageal echocardiogram Identifies thrombi on valves Medications to decrease the ventricular response - Metoprolol (Lopressor) Oxygen Prophylactic anticoagulation Lovenox - Coumadin – long term Cardioversion
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Cardiac Monitoring Atrial Fibrillation Tx: Medications to decrease the ventricular response Narrow QRS irreg rhythm–diltiazem; beta-blockers Wide QRS reg rhythm – amiodarone Wide QRS irreg rhythm – digoxin, diltiazem, verapermil, amiodarone Oxygen Prophylactic anticoagulation Cardioversion
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Cardiac Monitoring Atrial Fibrillation Cardioversion Synchronized countershock 50 – 100 Joules Avoids delivering shock during repolarization Patent intravenous line Patient sedated – Versed Oxygenation ABC Assess: VS, PO, Monitor cardiac rate - rhythm Administer antidysrhythmic medication
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Cardiac Monitoring Junctional Escape Rhythm
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Impulse generated from AV nodal cells at the AV Junction Escape pacemaker Rate 40-60 beats/ min Transient Assess: Patient hemodynamic stability
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Cardiac Monitoring Premature Ventricular Contractions
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Cardiac Monitoring NSR – V. Tach – V. Fibrillation
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Cardiac Monitoring Ventricular Tachycardia
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Cardiac Monitoring Ventricular Dysrhythmias
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Cardiac Monitoring Premature Ventricular Contractions
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Cardiac Monitoring Premature Ventricular Contractions (PVCs)_ Early ventricular complexes Followed by compensatory pause Fit between two NSR beats - interpolated Unifocal, multifocal, couplet, triplets, bigeminy, trigeminy, quadrigeminy 3+ = ventricular tachycardia Etiology: myocardial ischemia, <K+, CHF, metabolic acidosis, airway obstruction
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Cardiac Monitoring Premature Ventricular Contractions (PVCs/ Ventricular Tachycardia with Pulse Assess: LOC, hemodynamic status-- continuous cardiac monitoring of rhythm & rate, VS, PO, peripheral perfusion Tx: Underlying cause + Oxygen, Amiodarone IV bolus / Infusion
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V. Tachycardia/V. Fibrillation Pulseless TX: CPR BLS - Airway, Breathing, Circulation Shockable Rhythm VT/VF: Defibrillate – 120-200 Joules CPR x 5 cycles Check rhythm – shockable? Defibrillate (biphasic 200 J / monophasic 360 J Resume CPR Epinephine 1 mg IV (repeat q3-5 mins) / Vasopressin CPR x 5 cycles Check rhythm – shockable? Defibrillate (biphasic 200 J / monophasic 360 J Resume CPR Antiarrhythmics: amiodarone/lidocaine Magnesium – torsades de pointes Advanced Cardiac Life Support Defibrillation – V Fib / pulseless & polymorphic V tach Meds:
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Cardiac Monitoring V Fib - Agonal Rhythm
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Common Causes of Dysrhythmias Cardiac Accessory pathways, conduction defects, congestive heart failure, left ventricular hypertrophy, myocardial cell degeneration, myocardial infarction Other Conditions 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
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Cardiac Monitoring Heart Block 1 st, 2 nd Types I & II
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Cardiac Monitoring Heart Blocks
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Cardiac Monitoring First Degree AV Block 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 Assess: Hemodynamically stable Tx: withhold offending medication; oxygen; atropine, notify physician; observe
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Cardiac Monitoring Second Degree AV Block Mobitz Type I - Wenckebach 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 Etiology: Often transient following anterior / inferior wall MI – may revert to 1 st Degree AV Block Assess: Hemodynamic stability Tx: Atropine / May require Temporary Transcutaneous Pacemaker / CPR / ACLS Protocol
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Cardiac Monitoring Second Degree AV Block Mobitz Type I - Wenckebach
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Cardiac Monitoring Second Degree AV Block Mobitz Type II 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 Assess: Hemodynamic stability 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 Etiology: Anterior Wall MI; hypoxemia, electrolyte disturbances, cardiac surgery
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Cardiac Monitoring Third Degree AV Block Assess: Hemodynamic stability Tx: CPR ACLS Protocol Pacemaker
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Cardiac Monitoring Paced Rhythm
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Indications for Permanent Pacemaker 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
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Cardiac Monitoring Ventricular Standstill Pulseless Asystole CPR ACLS Protocol Tx: Atropine, Epinephrine, dopamine
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Pulseless Asystole Shockable Rhythm? No – BLS/CPR Shockable Rhythm? No – BLS/CPR Epinephrine 1 mg IV (may repeat q3-5 mins) Epinephrine 1 mg IV (may repeat q3-5 mins) (or one dose of Vasopressin) (or one dose of Vasopressin) Atropine Atropine 5 cycles of CPR 5 cycles of CPR Shockable rhythm? NO - CPR Shockable rhythm? NO - CPR Yes – Pulseless V Fib Yes – Pulseless V Fib
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Cardiac Dysrhythmias ASSESS THE PATIENT Treat the underlying cause Support hemodynamically Emergency Cardiac Medication CPR Transcutaneous/Transvenous pacemaker Information and emotional support to patient & family
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New Cardiac Advances Implantable cardioverter – defibrillator (AICD) Automatic external defibrillator (AED) ABCD Cardiac Ablation Therapy BLS ACLS
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