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Cardiac DYs

QuestionAnswer
Conduction System of the Heart Extrinsic Autonomic Nervous System
Sympathetic fight or flight reflex
Parasympathetic slows heart rate and decease force of contractions.
Automaticity An inherent (intrinsic) ability of the heart muscle tissue to initiate electrical impulse and contract in a rhythmic pattern
Irritability (Excitability): The ability of the heart muscle tissue to respond to a stimulus
Sinoatrial (SA) Node Located in the upper part of the RA Site of normal impulse origin; pacemaker of the heart Intrinsic ability to generate 60-100 beats per minute
Atrioventricular (AV) Node Located at the base of the RA Slows the impulse to allow the atria to contract and the ventricles to fill with blood Intrinsic ability to generate 40-60 beats per minute Serves as the back-up pacemaker of the heart
Bundle of His Divides into the right and left bundle branches that extend down the sides of the interventricular septum
Purkinje Fibers Fine conduction fibers deep in the ventricles Serves as the final back-up pacemaker of the heart Intrinsic ability to generate 20-40 beats per minute. contraction emptys of the ventricles
Cardiac Cycle is composed of both the electrical activity caused by automaticity and the mechanical or muscular response known as contraction
Electrical Activity Depolarization and Repolarization
Mechanical Activity Systole and Diastole
Can you have electrical activity with out machanical Activity? YES..Electrical activity precedes mechanical activity
Identify the flow of electricity through the heart's conduction system SA node > AV node > Bundle of HIS Purkinje Fibers
12 different leads - GIVE HOW MANY VIEWS 10 electrodes -4 electrodes (wires) attached to each of the limbs 6 electrodes (wires) placed around the chest
Electrode Placement Limb electrodes are placed on the limbs or on the body close to where the limbs join the torso (left and right shoulder; left and right abdomen below the umbilicus)
Electrode Placement V1- 4th Intercostal Space (ICS); Right Sternal Border V2- 4th Intercostal Space (ICS); Left Sternal Border V3- Halfway between V2 and V4 V4- 5th (ICS); Lt Midclavicular Line V5- 5th ICS; Lt Anterior-Axillary Line V6- 5th ICS; Lt Mid-Axillary Line
Electrocardiogram Standard 12-Lead (Views) ECG 3 Standard limb leads (Views) Leads I, II, and III
Standard 12-Lead (Views) ECG) 3 Augmented voltage limb leads (Views): Leads aVR, aVL, and aVF
6 Precordial leads (Views): Leads V1, V2, V3, V4, V5, and V6
Out of the 9 leads what is the 10th Ground
Precordial Leads: 6 Precordial leads (chest leads) are positioned onchest wall directly over the heart. Unipolar leads (positive electrode) and the heart as a center reference
Horizontal boxes measure time Small Box = 0.04 seconds or 40 milliseconds 5 Small Boxes= 1 Large Box Large Box = 0.20 seconds or 200 milliseconds 5 Large Boxes = 1 seconds or 1000 milliseconds
Vertical boxes measure voltage or amplitude: Small Box = 0.1 mV (1 mm2) Large Box = 0.5 mV (5 mm2)
Waveforms and Intervals The normal ECG tracing is composed of P, Q, R, S, and T waves.
These waveforms emerge from a flat baseline called (neither positive nor negative isoelectric line
Any waveform projected above the isoelectric line is considered positive
any projected below the line is considered negative
PR Interval Normal PR interval is ___ 0.12 to 0.20 seconds (3-5 small boxes)
PR Interval Measured from ___ beginning of the P wave to where the QRS complex begins
PR Interval---define PR interval measures the time it takes for the impulse to depolarize the atria, travel to the AV node, and then dwell there briefly before entering the Bundle of His.
Q Wave: First negative deflection after the P wave May or may not be present Pathologic if > 0.04 seconds or more than ¼ height of R wave (Seen in patients who have had MI)
R Wave: First positive or upright deflection after the P wave R wave is normally tall; amplitude varies across leads R prime (R’) is a second positive deflection in the QRS complex
S Wave Negative deflection after the R wave The waveform must go below the isoelectric line Second negative deflection S prime (S’)
QRS Complex Generic term for the waveforms that indicated ventricular depolarization Many people do not have all three distinct waveform in their QRS complex
QRS Interval: Measured from the beginning to end of QRS complex First deflection, either neg (Q wave) or pos (R wave), that follows the P wave indicates the beginning of the QRS interval Normal QRS interval is 0.06-0.12 seconds (1.5-3 small boxes)
T Wave: Represents Represents ventricular repolarization
What does the T wave follow? the QRS complex
T wave amplitude should be no greater _____ than 5 small boxes (5 mm high) and upright
Changes in T wave amplitude can indicate _____ electrical disturbances resulting from electrolyte imbalance or MI. For example, hyperkalemia can cause tall, peaked T waves; inverted T wave = ischemia
Waveforms and Intervals ST Segment: Connects the QRS complex to the T wave ST segment is usually isoelectric, or flat In some conditions the ST segment may be depressed (falling below baseline) or elevated (rising above baseline)
ST segment depression = Ischemia
ST segment elevation = Injury or Infarct (MI)
Waveforms and Intervals QT Interval:Measured from the beginning of the QRS complex to the end of the T wave
QT Interval: Measures the time taken for the ventricular depolarization and repolarization
QT Interval: Normal QT intervals are based on ___ HR (0.32-0.50 sec)
QT Interval: The slower the __, the longer the normal __ The faster the __, the shorter the normal __ Represents refractory periods of the ventricles Normal QT intervals are based on HR (0.32-0.50 sec) The slower the HR, the longer the normal QT The faster the HR, the shorter the normal QT Represents refractory periods of the ventricles
Waveforms and Intervals U Wave: A small waveform of unknown origin If present, it immediately follows the T wave and is of same deflection (T wave positive  U wave positive)
U Wave is an abnormal or normal finding? U wave is sometimes a normal finding (Dx of disease should be dependent on more specific indicators)
U waves may be seen in patients with electrolyte imbalance (Hypokalemia) and in those who have had an MI
Interpretation of Dysrhythmias Systemic analysis focuses attention on the following areas: Rhythm Regularity (Rhythmicity): both atrial and ventricular Rate: both atrial and ventricular Waveform Configuration and Location Intervals
Determine Rhythm Regularity must be___ Must be analyzed in both the atria and the ventricle
Determine Rhythm Regularity:P waves are used to establish atrial regularity
Determine Rhythm Regularity:R waves are used to establish ventricular regularity
Regular rhythm if __________ between points (peak P wave or peak R wave) one small box or less
Irregular Rhythm: Regular Irregular: rhythm that has a pattern Irregular Irregular: rhythm that has no pattern (A-Fib)
Determine Rate:Normally, the atria and ventricles depolarize at__________ the same rate
P waves are used for calculation of the atrial rate
R waves are used for calculation of the ventricular rate
Rule of 1500 is used is used to calculate the exact rate of a regular rhythm
Rule of 10 is used to calculate the approximate rate of either regular or irregular rhythms
Rule of 1500: Regular Rhythm (Exact) 2 consecutive P or R waves are located; the tallest point of either P or R wave is located Number of small boxes between the tallest points of 2 consecutive P or R waves is counted, and divided into 1500 to determine the HR in beats per minute
the 5 things you need to read P, PR, QRS, Rate, Rytheme
Waveform Configuration & Location Normal waveforms P, Q, R, S ,and T should occur in their natural order P wave should precede each QRS QRS complexes should be followed by T wave T waves should be followed by the next subsequent P wave
Intervals A final important aspect of the systematic analysis of rhythm strips is the assessment of the intervals. Assess the following intervals: PR Interval QRS Interval QT Intervals
Identify the waves and intervals of a normal ECG tracing, then state the electrical activity they represent and their normal time intervals. P wave: Atrial Depolarization PR Interval: 0.12-0.20 seconds QRS Complex: Ventricular Depolarization QRS Interval: 0.06-0.12 seconds ST Segment: Isoelectric, or flat T wave: Ventricular Repolarization; Upright
Dysrhythmias Any cardiac rhythm that deviates from normal sinus rhythm (normal conduction and intervals).
Dysrhythmias Results from alteration in the formation and conduction of impulses from the SA node to the rest of the myocardium. Results from irritability (excitability) of myocardial cells that generate impulses.
Dysrhythmias: treat- yes or no NO.-Signs and symptoms and treatment depends on the type and severity of the dysrhythmia.
Normal Sinus Rhythm rhythm originates in the SA node
Normal Sinus Rhythm is characterized by: Rhythm: regular (consistent R-R and P-P) Rate: 60-100 bpm P waves: precede each QRS complex, normal configuration, and each P wave is identical PR Interval: normal (0.12-0.20 second) QRS Interval: normal (0.06-0.12 second) T Waves: upright
Common Dysrhythmias Sinus Tachycardia Sinus Bradycardia Supraventricular Tachycardia Atrial Flutter and Atrial Fibrillation Atrioventricular Block Premature Ventricular Contractions Ventricular Tachycardia Ventricular Fibrillation Ventricular Standstill or Asystole
Sinus Tachycardia ST: rapid, regular rhythm originating in the SA node
Sinus Tachycardia Etiology: ST is a normal response (gradual) to stimulation of the sympathetic nervous system
Sinus Tachycardia Clinical Manifestation Many patients asymptomatic Occasional palpitations Hypotension Angina SOB Diaphoresis
Sinus Tachycardia Medical Management: Directed at treating the underlying cause Normally not caused by cardiac problem
Sinus Bradycardia slow, regular rhythm originating in the SA node
Sinus Bradycardia Etiology: Parasympathetic nervous system is stimulated, causing decrease in heart rate
Sinus Bradycardia Clinical Manifestation:R/T Degree of Decrease CO) May be asymptomatic Decrease LOC Fatigue Hypotension Lightheadedness and Syncope SOB Chest Pain Pulmonary Congestion
Sinus Bradycardia Medical Management: Directed toward the primary cause Maintain cardiac output Pacing (Transcutaneous, Transvenous, Permanent) Medications: Atropine (0.6-1.0 mg IVP). Dopamine (5-20ug/kg/min). Epinephrine (2-10ug/min). Isoproteronol (2-10ug/min
Supraventricular Tachycardia SVT: sudden onset of a rapid rhythm originating above the AV node (usually in the atria)
Supraventricular Tachycardia Etiology: Typically associated with increased automaticity. Causes include: Drugs (Digs) Alcohol Mitral Valve Prolapse; Injury to the Atria; Pericarditis Emotional Stress Pulmonary Disease Smoking Hormone Imbalance Electrolyte Imbalances Hypothermia
Supraventricular Tachycardia Clinical Manifestation: Palpitations Decrease LOC Hypotension Fatigue Lightheadedness SOB/Dyspnea Chest Pain
Supraventricular Tachycardia Medical Management Looks at how well the patient tolerates the dysrhythmia and at the overall clinical picture.
SVT:Medical Management: focus Focus is aimed at decreasing the HR and eliminating the underlying cause.
Atrial Fibrillation Electrical activity in the atria is disorganized, causing the atria to fibrillate or quiver rather than contract as a unit
Atrial Fibrillation Characterized by Rhythm: IIR Rate: Atrial: Not measurable (350-600 bpm) Ventricular:(100-180 bpm); RVR (rapid ventricular response)-patient may present unstable P : Not distinguishable PR: Not measurable QRS: Usually normal (0.06-0.12 sec) T: upright
Atrial Fibrillation Etiology: Typically associated with heart and pulmonary disease.
Atrial Fibrillation Causes include Atherosclerosis MI and Cardiac Surgery Hypertension Pulmonary Embolism Mitral Valve Disease CHF, Cardiomyopathy (Congenital Abnormalities) Chronic Obstructive Pulmonary Disease (COPD) Thyrotoxicosis
Atrial Fibrillation Clinical Manifestation: Palpitations Decrease LOC Hypotension Fatigue Lightheadedness SOB and Dyspnea Angina (Chest Pain) S/Sx of Decrease Cardiac Output Thrombi formation which may lead to embolisms (PE, MI, CVA, Periphery)
Atrial Fibrillation Medical Management Focus on treating the irritability of the atria, slowing the ventricular response (rate control), converting rhythm, and correcting the underlying cause
Atrial Fibrillation:Goal of therapy is to prevent atrial thrombi from becoming embolisms in the body. Anticoagulation (Heparin, Coumadin)
Atrial Fibrillation:Pharmacologic Cardioversion Calcium Channel Blockers (Diltiazem, Verapamil), Antidysrhythmics (Amniodarone), Beta Blockers, Digoxin.
Electric Cardioversion: Synchronized Electric Shock
Atrial Flutter A dysrhythmias that arises from a single irritable focus in the atria Waveform associated with Atrial Flutter are flutter waves or F waves Waveform has an appearance much like the teeth of a saw’s blade;continually & perfect regularity
Atrial Flutter Characterized by Rhythm: Reg (Fixed Ratio: 2:1, 3:1, 4:1) Rate: Atrial: 250-350 bpm Ventricular: Variable; depends on AV node conduction P: Replaced with multiple flutter waves PR: Not measurable QRS: Usually normal (0.06-0.12 second) T: Not distinguishable
Atrial Flutter Etiology: Most commonly seen in patients with heart (valvular) disease.
Atrial Flutter Causes include Causes similar to A-Fib Atrial Stretching and Enlargement CAD/Atherosclerosis Hypertension Valvular Disease CHF, Cardiomyopathy (Congenital Abnormalities) Stimulants
Atrial Flutter Medical Management: Focus on treating the irritability of the atria, slowing the ventricular response (rate control), converting rhythm, and correcting the underlying cause
Atrial Flutter Electric Cardioversion: Synchronized Electric Shock. Radiofrequency Catheter Ablation
Atrioventricular (AV) Blocks Defect in the AV Node (Junction) impairs conduction of impulses from the SA node to the ventricles. Impairment may cause slowed conduction of impulses, intermittent blockage of impulses, or complete blockage of impulse conduction.
Atrioventricular (AV) Blocks Three Kinds: First Degree AV Block Second Degree AV Block (Type I and Type II) Third Degree AV Block
First Degree AV Block; Delayed conduction through the AV junction and shown--- on the ECG as a prolong PR interval
First Degree AV Block Characterized by: Rhythm: Regular Rate: Normal (Often Sinus Bradycardia) P waves: precede each QRS complex, normal configuration, and each P wave is identical PR Interval: Prolong (greater than 0.20 seconds) QRS: Usually normal (0.06-0.12 second) T: Upright
First Degree AV Block Etiology First Degree Block is a common dysrhythmia in the elderly and in patients with cardiac disease (Atherosclerosis, CHF). As the normal conduction pathway ages or becomes diseased, impulse conduction becomes slower than normal.
First Degree AV Block:Clinical Manifestations: Usually, no hemodynamic changes are associated
First Degree AV Block Medical Management: Assess and treat hemodynamic (decrease CO) instability R/T Bradycardia.
Second Degree AV Block: Type I Mobitz I or Wenckebach Occurs at the level of the AV Node and is illustrated by a steadily lengthening of PR interval until the AV Node is unable to conduct one or more electrical impulses to the ventricles.
Second Degree AV Block: Type I Characterized by: Rhythm: Reg (P-P) Irreg (QRS-QRS) Rate: Normal (Often S.B with Pause); P > QRS P: precede each QRS complex, normal configuration, and each P wave is identical; Ratio 1:1 for 2, 3, or 4 cycle then 1:0; dropped P PR: Progressive lengthening until QRS c
Second Degree AV Block: Type II Mobitz II is a more severe form of AV Block Conduction delay occurs below the AV Node, often at the level of the bundle branches.
Second Degree AV Block: Type II:SA Node generate impulses, P wave occur at regular intervals, but----- SA Node generate impulses, P wave occur at regular intervals, but impulses are occasionally blocked, resulting in a P wave with no QRS after it.
Second Degree AV Block: Type II May progress to the more clinically significant third degree block
Second Degree AV Block: Type II Characterized by: Rhythm: Regularly (P-P) Irregular (R-R) Rate: Normal or Sinus Bradycardia; P wave > QRS complex P waves: More P waves than QRS complexes; Ratio 2:1, 3:1 PR Interval: Normal or prolonged but constant QRS: Normal for conducted beats T: Upright
Second Degree AV Block: Type II-Etiology: Medications (digitalis, beta blockers). CAD Hypoxemia.
Second Degree AV Block: Type II:Clinical Manifestations: Signs of decreased cardiac output (hypotension, chest pain, SOB, decrease LOC).
Second Degree AV Block: Type II:Medical Second Degree AV Block: Type II:Management: Prepare for pacing (Transcutaneous followed by Transvenous, and potentially permanent
Third Degree AV Block Complete Heart Block, AV Dissociation. No relationship between P wave and QRS complexes
Third Degree AV Block:Characterized by Rhythm: Reg (P-P);Irreg (R-R) Rate: Atrial: Norm; VT: Generated in the ventricle, and usually 20-40 bpm. P: More P waves than QRS complexes PR: Not Measurable. QRS: Prolonged; wide and bizarre (looks like a PVC) T: Usually inverted (as with PVCs).
Third Degree AV Block Etiology: Medications (digitalis, beta blockers). CAD Hypoxemia.
Third Degree AV Block Clinical Manifestations: Signs of decreased cardiac output (hypotension, chest pain, SOB, decrease LOC).
Third Degree AV Block Medical Management: Pacing (Transcutaneous followed by Transvenous, and most likely placement of a permanent pace maker).
Premature Ventricular Contraction(PVC Common ventricular dysrhythmia; the beat can be generate anywhere in the ventricles. Foci (Unifocal, Multifocal); Pattern (Bigeminy, Trigeminy); Sequence (Couplet, Triplet)
Ventricular Tachycardia (VT) VT is a rapid, life-threatening dysrhythmia that originates in the ventricles.Three or more PVCs in a row.
Characterized by: Rhythm: reg. Rate:140-240 beats per minute. P: Not visible (depolarizing ventricles). PR: Not Measurable QRS: Prolonged; Wide (greater than 0.12 secs) and Bizarre T: Usually deflected opposite the QRS complex; Is difficult to identify.
Ventricular Tachycardia (VT) : Acute MI, Hypoxemia, Metabolic Acidosis (Especially Lactic Acidosis), Electrolyte Disturbances (Potassium and Magnesium), Drug Toxicity (Digitalis).
Clinical Manifestations Pulselessness.
Ventricular Tachycardia (VT)Medical Management: Depends on if rhythm is stable or unstable (Pulse or Pulseless) Stable with Pulse: Medications  Synchronized Cardioversion Unstable with Pulse: Synchronized Cardioversion Pulseless: Basic Life Support (BLS)  Defibrillation  ACLS ASAP
Ventricular Fibrillation (VF) VF is a chaotic, life-threatening dysrhythmia characterized by a quivering of the ventricles that results in total loss of CO. VF is a state of clinical death. VF (Fine, Coarse)
Pacemaker Device that delivers an electrical current to stimulate depolarization of the heart via electrodes (atria, ventricles).
Pacemaker: used for treat symptomatic bradycardia, second degree AV block (type II) and third degree AV block. Pacemakers can be set at a fast rate to overdrive or interrupt symptomatic tachydysrhythmias.
Pacemaker Permanent Transvenous Epicardial
Pacemaker: Temporary: Transthoracic Transvenous Epicardial
Cardioversion Synchronized electric shock Synchronized electric shock to disrupt the ectopic pacemaker that is causing the dysrhythmia and allow the SA node to take control. Used for Tachydysrhythmias
Which nursing diagnosis focuses on the abnormal aspects of dysrhythmias? Decreased cardiac output
Nursing Interventions Pulseless Arrest Interventions: Basic Life Support (BLS) ACLS ASAP
Nursing Interventions Bradydysrhythmia Interventions Avoid activities that increase vagal tone (vomiting, gagging, valsalva maneuver, or endotracheal suctioning). Medications (Atropine, Epinephrine) Cardiac Pacing.
Created by: ninja3lake