ECGs Flashcards
Arrhythmias (dysarrhythmia)
Abnormal cardiac rhythm
*Prompt assessment of abnormal cardiac rhythm and patients response is critical
12 - Lead ECG
Looks at 12 areas in the heart Anterior Lateral sides Septum NOT posterior or right ventricle
P
Atrium depolarization ( SA node fires causing atrium to contract) if patient has a P wave they are in sinus rhythm
PR interval
- What does it measure
- What is the normal PR interval
- What is the PR interval represent
- Measures from the beginning of the P wave to the beginning of the of the QRS complex.
- Normal PR interval is 0.12-0.20 (5 small squares)
- The PR interval represents atrial depolarization
QRS Complex
- What does it measure
- What is the normal QRS complex
- What is the QRS complex represent
- Measure this complex from the beginning of the Q wave until the end of the S wave.
- The normal QRS complex is 0.04-0.10 seconds (2 1/2 small squares)
- The QRS complex represents ventricular depolarization…… Atrium repolarization
NB: Remember that not all QRS complexes contain all the QRS waves! Q-first deflection is negative R- Postive deflection after a Q wave S- Negative deflection after an R wave
T wave
Repolarization of ventricles (relax and resting)
QT interval
- Where to measure it
- What does it measure?
- Normal?
- Prolonged QT interval means?
- Beginning of QRS till the end of the T wave
- Measures the length of the time it takes for the ventricle to contract and relax
- Normal QT interval: 0.35-0.45 seconds
- Can lead to life-threatening arrythmias ( low magnesium (alcohol can lower))
ST segment
- below the isoelectric line
- Above the isoelectric line
Place a ruler under the PR interval
1** If the bottom part of the ST segment line is more than one small square (1mm) below the PR interval, then the patient is having myocardial ischemia
2** If the bottom part of the ST segment is more than small square(1mm) above the PR interval, then the patient is probably having a MI
Small square seconds
0.04 second
Large square seconds
0.02 seconds
Number of large squares in a 6-second strip
30
Phases of Cardiac Action Potential
phase 0: Upstroke or rapid depolarization and corresponds with ventricular contraction
: Initial impulse
Phase 1,2,3 Repolarization
1: Overshot
2: plato (little change) opening of the Ca channels helps to sustain contraction… CCB work here
If someone has a low EF (
If the rhythm is regular 2 methods to estimate HR
1.
2.
- Count the number of QRS complexes in a 6 strip x 10
- Count number of small squares between two R waves and divide into 1500.
Count number of large squares between two R waves and divide into 300
Steps in assessing the Cardiac Rhythm
Steps 1-7
Step 1: Heart rhythm (regular vs irregular) P-P/ R-R intervals identical Step 2. Heart Rate Step 3. P waves Step 4. PR interval Step 5. QRS Complex Step 6. ST Segment Step 7. T wave
Normal Sinus rhythm ECG characteristics
Rate: 60-100 bpm P present P waves precede every QRS complex P-R ratio is 1:1 Causes: normal Tx: always be sure your patient has a pulse
The absolute refractory period
occurs when excitability is zero and the heart tissue cannot be stimulated. Nothing is strong enough to elicit another contraction
Beginning of the QRS complex till middle of the T wave
The relative refractory period
Heart is almost back to normal but is still unstable
Occurs from the middle of the T wave till the end.
If a strong enough impulse hits this area can cause life-threatening arrythmias… R on T phenomenon
ST- elevation
MI coronary artery is occluded
ST- depression
Ischemia or non stemi MI
Partically goes through whole ventricle
Deep and wide q waves (had a previous MI) St will go back to normal
Sinus Bradycardia
Rate: less than 60
P present
P waves precedes each QRS complex
P-R ratio is 1:1
Causes of Sinus Bradycardia
2.S/S
Carotid sinus massage Hypothermia Increased vagal tone Administration of parasympathomimetic drugs *Hypothyroidism * increased ICP *Obstructive jaundice * Inferior wall MI 2. Pale, cool skin, hypotension, weakness,angina,dizziness or syncope, confusion,or disorientation, SOB
Sinus Bradycardia TX
Asymptomatic and hemodynamically stable:NONE
Symptomatic: ATROPINE
Temporary pacing
Dopamine/Epinephrine infusion
Sinus Tachycardia
Rate: >100/min
P present
P waves precedes every QRS
P-R ratio 1:1
Sinus Tachycardia Causes
- S/S
Exertion Anxiety Fever Anemia Stimulants Hyperthyroidism pain Drugs 2. S/S: Dizziness, dyspnea, hypotension, angina
Sinus Tachycardia TX
Determined by underlying causes
- B-adrenergic blockers to reduce HR and myocardial oxygen consumption
(Gold Standard in HF and ST elevation MI)
Supraventricular Tachycardia/ Narrow complex tachycardia (normal QRS)
Arrhythmias originating in an Ectopic pacemaker site in the atria (not SA node)
Involves enhance automaticity of arterial tissue or conduction of the Ectopic impulse
Rhythm is regular
Ventricular response is greater than 150/min and generally less than 200/min
No P wave
NO PR interval
QRS complex: 0.04-0.10
(If normal QRS -ectopic foci is in atrium
Causes Of Supraventricular tachycardia
Unknown etiology Emotional Stress Excessive intake of alcohol, caffeine, or tobacco valvular heart disease (Rheumatic) Coronary artery disease Digitalis toxcitiy
Tx of SVT
If Hemodynamically stable
Stable (hemodynamically)
- attempt vagal maneuver (slows down heart): Deep cough, Hold breath and bare down, Suction tracheal tubes make them gag stimulates vagus nerve.
- ADENOSINE Pharmacological cardioversion (stops the heart so somefully the SA node kicks in, short half life less than 6 sec, going to feel bad)
- If After 3 doses of adenosine, the rhythm continues and the patient is stable, the MD may order a CCB or Beta blocker
Tx of SVT
If Hemodynamically unstable
Unstable (diaphoretic, cold and clammy)
* synchronized cardioversion
Synchronized Cardioversion
The “SYNC” button is pressed on the machine so that every R wave is flagged
*If this is not done an R on T phenomenon may occur and the patient will go into a pulseless dysrhythmia
*Patient is sedated prior to the procedure
It stops Heart and hopefully SA node kicks in again
Pad placement
Not put over the nipple on the right side because it burns skin
Avoid piercings/ pacemakers
Give Versed - sedation blocks short term memory
Im clear your clear were all clear … Discharge
Have to put machine into synchronized mode each use
Atrial Flutter
Atrial Tachycardia identified by recurring, regular, sawtooth-shaped flutter waves
*May be fast, slow regular or irregular
Eropic foci 300x/min
Av node blocks so many of the impulses
One ectopic foci in the atrium initiating the rhythm
Atrium 300 ( 1 large square) but ventricles 75 ( 4 large squares)
AV node protects the ventricles
Atrial flutter occurs with usually:
CAD Mitral valve disorder Pulmonary embolus Chronic lung disease Cardiomyopathy (Atriums not able to empty properly so blood just sits and can form clots) Left artium has a pocket.. blood flows(if clots) goes into left ventricle and out the aorta -> stroke
Clinical significance of Atrial Flutter
The high ventricular rates (>100bpm) and the loss of the “atrial kick” can decrease CO and cause serious consequences such as Heart failure
Patients wit AFlutter are at increased risk for strokes b/c of the risk of thrombus formation in the atria from stasis of blood.
** Coumadin is used to prevent stroke in pts with atrial flutter of longer than 48 hour duration
NEED ANTICOAGULANTS
TX for Atrial Flutter if stable
Stable
- Amidodarone
- Digoxin
- Beta blockers
- CCB
- After therapeutic anti-coagulation, return for elective synchronized cardioversion
TX for Atrial Flutter if unstable
Synchronized cardioversion (if pulse)
TX for Atrial Flutter
Diltiazem, digoxin, beta blockers used to control ventricular rate
Antiarrhythmic drugs used to convert atrial flutter to sinus rhythm or maintain a sinus rhythm
Radiofrequency catheter ablation used a curative therapy ( a catheter is placed in the RA b/w the inferior vena cava and the tricuspid valve, with low voltage, high-frequency form of electrical energy the tissue is ablated(destroyed)
Atrial Fibrillation
Arrthymia arsing from Ectopic foci(many) in the atrium discharging impulses at a rate if 400 or more per min
*The atria quiver or fibrillate
* No P Waves
*NO PR interval
*GRS Complex 0.04-0.10 sec (NORM)
{Irregular HR} ASKA Fibrillation Causes
unknown etiology Associated with emotional stress or excessive alcohol consumption Valvular heart disease Hypertensive or coronary heart disease Cardiomyopathy Myocarditis Pericarditis Heart Failure Hyperthyroidism Pulmonary Disease Following cardiac surgery
Clinical significance of a fibrillation
Can often result in decreased CO b/C of ineffective atrial contractions or loss of atrial kick, a rapid ventricular response or both
Thrombi may form in the atria as a result of blood stasis. An embolized clot may develop and travel to the brain, causing a stroke.
- Overall risk for stroke increases five-fold with atrial fibrillation
Risk of stroke is even higher in pts with structural heart diseases, HTN, and over the age of 65 yrs old
- Anticoagulation with coumadin used to prevent strokes
Atrial fibrillation TX
Goals: decrease in ventricular response (to 48 hours before attempt at conversion to sinus rhythm
The cardioversion procedure can cause clots to dislodge which increases the patient’s risk for stroke
If on coumadin (takes 3-5 days to become therapeutic levels)
Measure INR normally want 2-2.5 (if to low- clot.. if to high-bleed… Heparin measure PTT
Newer non-vitamin K antagonist oral anti-coagulants (no tests to monitor.. give based on wt)
Davigatran (pradaxa)
Rivaroxaban (Xarelto)
Apixaban (Eliquis)
Ventricular arrhythmias
Ventricular arrhythmias originate in the ventricles below the branching portion of the bundle of HIS and includesL
Premature Ventricular Contractions (PVC’s)
Ventricular Tachycardia ( with or without a pulse)
Ventricular fibrillation. Most of these rhythms are or have the potential to be life threatening and demands immediate recognition and treatment
Premature Ventricular Contractions (PVC’s)
Rhythm: Underlying rhythm usually regular, irregular with PVC
The P wave none associated with PVC however p waves associated with the underlying rhythm
PR interval : not measurable
QRS for PVC wide bizarre, different from the QRS complexes of the underlying rhythm
PVC causes
Can be common becoming more frequent with age Unknown etiology and can occur in healthy hearts Anxiety Excessive caffeine and alcohol intake Drugs Hypoxia Acidosis Electrolyte imbalance CHF MI Valvular or ischemic heart disease Reperfusion following thrombolytic therapy and angioplasty, heart surgery or placement of leads or catheters in the ventricles
PCV TX
Tx is usually guided by the number of PVC’s usually the more concerning if greater then 6 min, couplets, runs of 3, or consecutive PVC’s, R on T phenomena
Tx is also guided by how symptomatic the patient is with the PVC
*reverse possible causes
*Amioodarone, lidocaine, Procainamide
Descriptors of PVCs
Unifocal- Look the same as coming from the same ectopic focus
Multifocal- look different as coming from various ectopiv foci
Bigeminy: every other complex is a PVC ex normal beat, PVC, normal beat,PVC
Trigeminy- Every third complex us a PVC
Couplet- Two PVC together
Triplet- 3 PVC together (aKA a 3 beat run of ventricular tachycardia)
Monomorphic ventricular Tachycardia
Rhythm: regular Rate: Greater thhan 140/min P waves: No P waves are associated with ventricular tachycardia. However SA node continues to beat independently and sinus P waves may occasionally be seen PR interval: not measurable QRS complex: Wide and bizarre
Monomorphic ventricular Tachycardia Causes
usually occurs b/c of some underlying heart disease Myocardial ischemia or infarction*** Cardiomyopathy Mitral valve prolapse CHF Digitalis toxicity Antiarrhythmic medications Electrolyte imbalances Reperfusion Mechanical stimulation of the endocardium by a wire or catheter
Monomorphic ventricular Tachycardia TX
Pulse and is stable
Pulse and is stable: **Amidodarone Lidocaine Procainamide *If Rhythm converts, then start and IV maintenance drip with the same antiarrhythmic that converted the rhythm
Monomorphic ventricular Tachycardia Pulse and unstable
Prepare of synchronized cardioversion
Monomorphic ventricular Tachycardia Pulseless and unresponsive
CPR
Defibrillation (b/c no pulse only used with pulseless ventricular tachycardia and fibrillation
— The machine is not in SYNC mode
—Before discharging the machine you still need to “clear” everyone
Polymonomorphic ventricular Tachycardia
Rhythm: regular or irregular Rate: greater than 150/min P wave: Not identifiable PR interval: not measurable QRS complex: wide and bizarre with variations in its electrical polarity T wave: not discernible
Polymonomorphic ventricular Tachycardia causes
Baseline QT normal: Same etiology as ventricular tachycardia
Baseline QT prolonged:
Look for causes of prolongation of QT interval
Low magnesium levels
Antiarrhythmic medications
Changes in medication
Tricyclic antidepressants
Haldol
Congenital long QT syndrome (esp if young pt)
Polymonomorphic ventricular Tachycardia TX
Baseline QT interval prolonged:( Torsade de Pointe) Magnesium 1-2 grams IV*
Ventricular Fibrillation
Rhythm: No pattern or regularity, Ventricular activity appears as Fibrillatory waves with no recognizable pattern Rate: Cannot be determine P waves: none PR interval: None QRS complex: cannot be determine
Ventricular Fibrillation Causes
CAD MI and Myocardial ischemia Untreated ventricular tachycardia Underlying Heart disease Acid-base imbalances Electric shock Severe hypothermia Drug toxicity Electrolyte imbalances Artifact: Not true rhythm if see patient and they're up and orientated not true v fib (electrical interference)
Ventricular Fibrillation TX
Same as pulseless ventricular tachycardia
*CPR
*Debrillation
Iv drug epinephrine ( everyone without a pulse gets it, it is a potent vasoconstrictor to increase blood flow to heart)
Implantable Cardiover-defibrillator
Programmed to read rhythms
Internal shock, hurts
Asytole
Rhythm: none
Rate: None
Complexes: none
Heart is stopped
Asystole Tx
Start CPR
Check a second lead to confirm asystole
When IV established give Epinephrine
may give vasopressin to replace first or second doese of epinephrine
If witnessed or known downtime consider transcutaneous pacing
Search for possible contributing factors
Pulseless Electrical Activity
You may have a rhythm on the monitor but no detectable pulse
Organized electrical depolarization occurs but no synchronous shortening of myocardial fibers
Pulse comes from contractility (squeeze)
Pulseless Electrical Activity causes
same as asystole
*advanced cardiac disease, a severe cardiac conduction system disturbances, or end -stage HF
Pulseless Electrical Activity Tx
Rapid identification and tx of underlying reversible causes is critical for treating PEA
Initiate CPR
Epinephrine
Vasopressin
Causes -Think about the H’s and T’s
H’s: Hypovolemia, hypoxia, Hydrogen ions(acidosis), Hypo-hyperkalemia, hypoglycemia, Hypothermia
T’s: Toxins/Tablets (drug overdose), Tamponade, Tension Pneumothorax, Trauma (hypovolemia, increased ICP)
AV Heart block
- An AV heart block is a disturbance in the atrioventricular conduction of the heart
- Normally AV node acts as a bridge b/w the atria and the ventricles
- An AV block is a failure or delay in conduction across the bridge
- The PR interval measures the time b/w the initial depolarization of the atria and the initial depolarization of the ventricles
AV heart block includes
First degree AV Block (mild)
Second degree AV block type 1
Seond degree AV block type 11
Third degree AV block or complete Heart block
Pacemakers
a battery-powered device that delivers an electrical stimulus to the myocardium resulting in contraction Reasons to pace a pt: Symptomatic Bradycardia Sinus Arrest Slow atrial fibrillation Alternating brady and tachy arrythmias Second degree heart block type 11 Third degree heart block Asystole
