| Term | Definition |
| 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 |
