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M6 13-005

Exam 4: Cardiovascular System; Cardiac Dysrhythmias

Conduction system of the heart Autonomic Nervous System
Autonomic Nervous System Sympathetic & Parasympathetic
Conduction System Heart Muscle Characteristics Automaticity & Irritability
Automaticity & Irritability Characteristics that affect the conduction system
SA Node Site of normal impulse origin
Bachmann's Impulse leaves the SA node, traveling through the atria via ____
40-60 BPM Impulse wave continues to the AV node of the heart @
Bundle of His Divides into the right and left bundle branches that extend down either side of the interventricular septum
Purkinjie Fibers Generates in impulse of 20-40 BPM
20-40 BPM Pukinjie Fibers impulse rate
Flow of electricity through hearts conduction system SA node> AV node> Bundle of his, (right and left bundle branches) Purkinjie Fibers
EKG (ECG) Graphic study of the recording of the electrical activity of the myocardium
Depolarization the conducted cardiac impulse transiently reverses membrane polarity. In this depolarized phase the myocardium is incapable of further contraction.
Repolarization The process whereby the membrane, cell, or fiber, after depolarization, is polarized again, with positive charges on the outer and negative charges on the inner surface.
EKG Machine Records the heart's electrical activity from electrode sensors placed on the skin
Hoizontal axis Represents time
Vertical Axis Represents voltage
.02 Seconds 1 square on rhythm strip equals
1 second 1 Block (5 squares) on rhythm strip equals
3 seconds 15 blocks on rhythm strip equals
Rate Determination Methods (4) Cardiac Ruler Method, Six second Tracing Method, 300 Method, 1500 Method
P, Q, R, S, and T Waves Components of the Normal ECG Complex
P Wave First positive deflection representing depolarization of the atria. (0-0.2 seconds)
Q Wave First NEGATIVE deflection after the P wave
R Wave First POSITIVE deflection after the P wave
S Wave NEGATIVE deflection after the R wave
QRS Complex Represents ventricular depolarization. (0.06-0.12 Seconds)
PR Interval Represents the time it takes an impulse to travel from the SA node across the atria t the AV node fibers (0.12-0.20)
T Wave Represents repolarization of the ventricle
ST Segment Represents early repolarization of the ventricular muscle.
Steps for interpreting the EKG Systemic analysis, Determine Heart Rate, Determine Rhythm
Rhythm Strip Find P waves, measure P-R interval, Measure the QRS complex, Find the T waves, Evaluate the ST segment, Measure the QT interval
Dysrhythmia Any cardiac rhythm that deviates from normal conduction with normal intervals. Results from irritability of myocardial cells that generate impulses.
Normal Sinus Rhythm (NSR) (StriP) Rate: 60-100 bpm Rhythm: Regular (Consistent R-R & P-P) P Wave: Present for each QRS complex, Normal config, normal P-R interval, Normal QRS interval, T wave upright
Types of Dysrhythmias Sinus Tachycardia, Sinus Bradycardia, Supraventricular Tachycardia, Atrial Flutter/Fibrillation, Atrioventricular Block, Premature Ventricular Contracions, Ventricular Tachycardia, Ventricular Fibrillation
Dysrhythmias are a result of what? Either an alteration of the formation of the impulse through the SA node to the rest of the myocardium or irritability of the myocardium cells.
Sinus Tachycardia (Strip) Rate: greater than 100 Rhythm: Regular P Wave: present for each QRS complex, normal config, and each P wave is identical P-R interval: normal QRS Complex: Normal T Wave: Normal
Sinus Tachycardia (Etiology) Sympathetic Nervous System stimulates the heart, increasing the rate. Increase is gradual.
Sinus Tachycardia (Causes) Anxiety Exercise Fever Shock, hypotension Medications (i.e. vasopressors, albuterol) Hyperthyroidism. Heart failure, angina Stimulants (caffeine, nicotine, amphetamines) Hypothermia, Pain
Sinus Tachycardia (Manifestations) Many Pt's asymptomatic, occasional palpitations, Hypotension, Angina, SOB, Diaphoresis, HF
Sinus Tachycardia (Medical Management) Directed at treating the underlying cause, normally not caused by cardiac problem
Sinus Bradycardia (Strip) Rate: Less than 60 BPM. Rhythm: R-R & P-P intervals are regular P Wave: Present for each QRS complex, normal configuration, and each P wave identical PR interval: Normal QRS Complex: Normal T Wave: Normal
Sinus Bradycardia (Etiology) Parasympathetic nervous system is stimulated, causing the SA node to slow
Sinus Bradycardia (Underlying Causes) Normal in the well-conditioned athlete Medications (B-blockers, digoxin) Hypothyroidism Cardiac diseases; predominately acute MI Sleep Hypothermia Vagal stimulation (i.e., vomiting, bearing down, holding breath) Intracranial tumors
Sinus Bradycardia (Manifestations) May be asymptomatic Fatigue Hypotension, Lightheadedness, and syncope
Sinus Bradycardia (Medical Management) Atropine (0.6-1.0 mg IVP) Transcutaneous pacing, until transvenous pacer available Dopamine (5-20ug/kg/min) Epinephrine (2-10ug/min) Isoproteronol (2-10ug/min)
Supraventricular Tachycardia (Strip) Rate: usually 150-250 Rhythm: Regular P Wave: Present for each QRS complex, normal configuration, and each P wave is identical PR Interval: Normal QRS Complex: Normal T Wave: Normal
Supraventricular Tachycardia (Etiology) Cause not typically associated with heart disease
Supraventricular Tachycardia (Manifestation) Palpitations, angina, lightheadedness, fatigue SOB, dyspnea Change in LOC
Supraventricular Tachycardia (Medical Management) Determine Pt tolerance of dysrhythmia Focus is aimed at decreasing the heart rate and eliminating the underlying cause Adenosine: 6mg-12mg-12mg
Atrial Flutter (Strip) Rate: Variable Rhythm: Regular or irregular P Wave: Multiple P's/QRS PR Interval: Varies (have to count it) QRS complex: Varies T Wave: May not be visible
Atrial Fibrillation (Etiology) Atherosclerosis Cardiac surgery, acute MI Mitral valve disease, cardiac stretch Digitalis preparations HF, cardiomyopathy, HTN, volume overload COPD (Chronic Obstructive Pulmonary Disease) Thyrotoxicosis
Atrial Flutter/Fibrillation (Manifestations) Palpations Lightheadedness Syncope Angina Change in LOC Pulmonary Edema Decreased Cardiac Output Thrombi form that may cause embolism
Atrial Flutter/Fibrillation (Medical Management) Focused on controlling rate, converting rhythm and providing anticoagulation. Synchronized cardioversion: if unstable, or unresponsive to meds Calcium channel Blockers Digoxin Amiodarone Heparin/Coumadin
Amiodarone used to help keep the heart beating normally in people with life-threatening heart rhythm disorders of the ventricles (the lower chambers of the heart that allow blood to flow out of the heart).
Atrioventricular Blocks A defect in the AV slows or impairs conduction
3 Types of Atrioventricular Blocks First Degree AV Block Second Degree AV Block (Types I & II) Third Degree AV Block
First Degree AV Block (Strip) Delayed conduction through the AV Node causes prolonged PR INterval
Second Degree AV Block (Type I) Mobitz I Wenckelbach
Second Degree AV Block (Type II) Mobitz II Classical
Third Degree AV Block Complete Heart Block complete AV Dissociation
Premature Ventricular Contractions Extra, abnormal heartbeats that begin in one of your heart's two lower pumping chambers (ventricles).
Premature Ventricular Contractions (Etiology) Irritability of the ventricular musculature
Premature Ventricular Contractions (Strip) Rate: Varies Rhythm: Usually regular w/ PVC coming earlier than next expected P Wave: No t visible, hidden in the PVC PR interval: not visible QRS Complex: Wide and bizarre (greater than 0.12 seconds "sore-thumb" appearance) T Wave:dflect opposite QR
Premature Ventricular Contractions (P Wave) the SA node continues to transmit impulses- but the impulses does not reach the ventricles because the ventricle is depolarized by the PVC
Premature Ventricular Contractions (Medical Management) Focus on treating the underlying cause. Evaluate Electrolytes Assess for hypoxia and treat prn Monitor for effect on hemodynamics
Ventricular Tachycardia (Strip) Rate: 140-240 BPM Rhythm: Regular Pwave: not visible QRS Complex: wide and bizarre (Greater than 0.12 secs) T Wave: usually deflected opposite to the QRS complex & difficult to see
Ventricular Tachycardia (P Wave) SA node continues to transmit impulses normally, until it becomes hypoxic, but impulses are not transmitted to ventricle, as ectopic focus is depolarizing ventricles
Ventricular Tachycardia (Etiology) Acute MI, Hypoxemia, Metabolic Acidiosis (especially lactic acidosis), Electrolyte disturbances (K+ & Mg+), Toxicity to certain drugs, such as digitalis or isoproterenol
Ventricular Tachycardia (Clinical Manifestations) Fatigue, SOB, Dyspnea, Lightheadedness, syncope, hyptotension, shock, chest pain, pulselessness
Ventricular Tachycardia (Medical Management) Depends on if rhythm os stable or unstable and whether VT is confirmed or suspected.
Ventricular Tachycardia (Drug Therapy) Amidarone, Lidocane, Magnesium, Procinamide
Ventricular Fibrillation Rapid and disorganized ventricular pulsation. Produces clinical death & must be reversed immediately, or Pt will die. SAWTOOTH!!!
Ventricular Fibrillation (Strip) Rate: Unmeasurable Rhythm: Irregular P Wave: Not present PR Interval: Not present QRS Complex: Not measurable (no definable complexes) T Wave: not present
Ventricular Fibrillation (Etiology) Myocardial ischemia or infarct Deteriorating ventricular rhythms (such as V-Tach) Acidosis Electrolyte imbalances Hypothermia Digitalis or quinidine toxicity
Ventricular Fibrillation (Manifestations) Loss of conciousness Loss of pulse, respiration and blood pressure Death
Ventricular Fibrillation (Management) Check pulse Airway: open the airway Breathing Circulation
Abnormality in ST Rate too high
Abnormality in SB Rate too low
Abnormality in SVT Rate too high May also have shortened PR interval
Abnormality in A Flutter Atrial rate too high May be irregular Ventricular rate may also be high
Abnormality in A Fib No P waves Irregularly irregular Ventricular rate may also be high
Abnormality in First Degree AV Block Prolonged PR interval
Abnormality in Second Degree AV Block (Type I) Irregular Consecutively prolonged PR interval until a QRS complex is dropped More Ps than QRSs
Abnormality in Second Degree AV block (Type II) Irregular P waves are not conducted More Ps than QRSs
Abnormality in Third Degree AV Block No relationship between P and QRS More Ps than QRSs Prolonged QRS
Abnormality in PVC Prolonged QRS
Abnormality in V Tach Rate too high No visible P waves QRS prolonged
Abnormality in V Fib No discernible waveforms
Antiarrhythmic Agents Suppression of cardiac arrhythmias
Antiarrhythmic Agents (Action) Correct arrhythmias bey a variety of mechanisms, depending on the group used
Antiarrhythmic Agents (Therapeutic Goal) Dcrease symptomatology and increase hemodynamic performance.
Antiarrhythmic Agents (Choice) Depends on etiology of arrhythmia and individual patient characterisitc
Antiarrhythmic Agents Class 1A (Drug) Disopyramide Procainamide Quinidine
Antiarrhythmic Agents Class 1B (Drug) Lidocane
Antiarrhythmic Agents Misc (Drug) Adenosine Digoxin
Antiarrhythmic Agents 1A (Mechanism) Depresses Na conductance, increases action Potential duration (APD) and effective refractory period (ERP), decreases membrane responsiveness
Antiarrhythmic Agents 1B (Mechanism) Increases K conductance, decreases APD and ERP
Antiarrhythmic Agents Misc. (Mechanism) Slows conduction through the AV node. Decreases conduction velocity and prolongs the effective refractory period in the AV node.
Antiarrhythmic Agents Nursing Implications Monitor BP, Pulse, and ECG before and routinely throughout therapy. Check Apical pulse before administering meds. Withhold if <50 or >120bpm. Monitor I&Os and daily weights.
Cardioversion Used for tachydysrhythmias when pharmacological intervention has been unsuccessful or the patient is compromised by a decreased cardiac output.
Current is discharged during cardioversion At the QRS Complex
Pacemaker Battery-operated device that initiates and controls the heart rate Used for patients with bradydysrhythmias, tachydysrhythmias, or 2nd and 3rd degree heart block that cannot be controlled with medications alone
Pacemaker dysfunction S/S Change in LOC, Bradycardia, Hypotension
Created by: jtzuetrong