Test 1 Flashcards
What is the difference between ECG and Continuous cardiac monitoring
Provides information about cardiac status
- as it is happening
- it does not diagnose pump problems(CHF, heart failure, cor pul)
- Records electrical activity in the heart
- records dysrhythmias
Dysrhythmias are caused by
Hypoxia, Ishemia, Sypathetic stimulation, drugs, Electrolyte imbalance, rate, stretch
1 reason adult cardiac arrest
Underlying heart problem
1 reason kids cardiac arrest
Resp failure/ Sepsis
Heart blood path
Superior Vena Cava, Inlet of the superior vena cava, right atrium, inlet of the inferior vena cava, Coronary sinus, Inferior vena cava, Coronary sinus, Inferior vena cava, Tricuspid valve, Right Ventricle, Interatrial septum, Interventricular Septum, Left atrium, Mitral valve, Left ventricle
During a fib. blood starts
elsewhere other than SA node
Heart conduction
- SA Node
- AV node
- Bundle of His
- Bundle branches
- Purkinje fibers
SA Node-
Automaticity
AV Node-
- Conduction is delayed at the AV node to allow the ventricles to fill with blood
- Also limits the rate of ventricular stimulation during excessive atrial firings
Purkinje fibers-
Finger like branches that penetrate the cardiac muscle
Properties of cardiac muscle
- Contractile muscle fibers
2. Auto-rhythmic cells
Contractile muscle fibers
Responsible for pumping activity of the heart, Make up bulk of musculature of myocardium
Auto-rhythmic cells
Make up 1% of cardiac cells, most found in SA node, cause myocardial fibers to contract, stimulate and create action potential
Four properties of cardiac muscle
- Automaticity
- Excitability
- Conductivity
- Contractility
Excitability
Response to stimulation or irritation, Ischemia and hypoxia cause myocardial cells to become more excitable (irritated)
Conductivity
Unique ability of the heart cells to transmit electrical current from cell to cell throughout the entire conductive system
Contractility
Is the ability of cardiac muscle fibers to shorten and contract in response to an electrical stimulus
Electrolytes responsible for electricity
- Potassium (K+)
- Sodium (Na+)
- Calcium (Ca2+)
Nervous System Role
plays important role in the rate of impulse formation, conduction, and contraction strength
Sympathetic stimulation role
- Cause increase in HR
- Increase in AV conduction
- Increase in heart contractility
- increase in excitability
Parasympathetic role
- Decrease in HR
- Decrease in AV conduction
- Decrease in contractility
- Decrease in excitability
Continuous Cardiac Monitor 5 leads
White in the clouds over grass (green), with crap in the middle, then smoke (black) over fire (red)
Ectopic beat
any heart beat originating outside the SA node
Foci/Focus
Where the ectopic beat originates
Dysrhythmias
abnormal cardiac conduction, also termed arrhythmia
Escape beat
a heart beat that originates outside the sinus node after a period of SA node inactivity
Myocardial ischemia
partial or complete obstruction of blood flow, reducing oxygen supply to the heart
angina
chest pain associated with reduced coronary blood flow
Stable Angina
Persistent reoccurring chest pain that usually occurs with exertion
Unstable Angina
Unexpected chest pain, usually occurring during rest. Chest pain is usually more intense and lasts for a longer period of time
Myocardial infarction
death of muscle tissue
Atrial kick
Responsible for cardiac output (10-30% ventricular filling)
Heart block
Conduction stopped or insignificantly delayed
Automaticity
ability of heart to beat on own
PVCs
Premature ventricular contractions
Syncope
Fainting (lack of blood flow)
STEMI
ST elevated myocardial infarction (BAD)
Normal rates: SA Node, AV junction, Bundle Branches, Purkinje Network
SA- 50-100
AV- 40-60
Bundle-30-40
Purkinji- 30-40
Steps to reading ECG
- HR
- Heart rhythm (reg/ irreg) R-R interval
- Presence of P wave
- Is there a QRS following each P wave
- PR interal (is it less than 0.20)
- QRS complex (Is it less than 0.12 seconds)
- ST segment (baseline)
PVC
Wide ectopic beat from ventricles
ECG systems use the same standard paper and run at the same speed of
25mm/sec
Each small ECG square=
0.04
Each large ECG square=
0.20, containing 5 small squares
1 second on a ECG strip=
5 large squares
Ventricle rhythm, comparing the R-R ratio with the longest/ shortest… how many seconds to make irregular
> 0.12
P Wave
Represent atrial conduction originated in the SA node, Paces the heart.
- Less than 2.5 mm in height
- more than 0.10 seconds in length
PR Interval
Normal 0.12-0.20 seconds
-Longer= delay in conduction through the AV node (AV block)
Complete heart block=
third degree heart block
QRS Complex
-Normal is less than 0.12 seconds long,
Represents ventricular depolarization
Rules of QRS
- If the first deflection is downward than it is a Q wave
- The initial upward deflection is an R wave
- The first neg. deflection following R is an S wave
- QS is a negative deflection with no positive deflection at all
- regardless of missing waves it is still called QRS complex and represents ventricular depolarization
T wave
reflects ventricular repolarization, inverted T waves suggest ischemia
ST segment
Normally baseline, A depressed ST segment suggests myocardial ischemia
-an elevated segment suggests myocardial infarction
Sinus Dysrhythmias
Sinus bradycardia- Regular rhythm, HR < 60bpm,
Sinus tachycardia- Regular rhythm, HR 100-160bpm
Supraventricular Tachycardia
Ventricular rate: 150-250bpm
- Regular rhythm
- P waves may be hard to see
- Narrow QRS
- Connect SVT to adenosine as first line drug
- Cardioversion
Cardioversion
machine cardioverts on R wave (synchronize)
Resents heart
Defibrillation
shock whenever
Atrial flutter
-flutter or saw tooth wave is produced by same ectopic beat (outside SA node)
-Flutter wave replaces P (sinus)wave
-Atria Rate 250-350bpm
Commonly seen in pts with atrial fibrillation
Complications of atrial flutter
-Diminishes atrial filling: results in minimal atrial assistance in filling the ventricles (10-30% CO)
-Development of thrombi in atrial walls: need for blood thinners
(blood in atrial for too long)
Atrial Fibrillation
- The AV node is bombarded with hundreds of ectopic atrial beats at various rates and amplitudes
- atrial rate: >400 (chaotic and irregular)
- RHYTHM is regular
Treatment options for A. Fib.
Reduce the heart rate with cardioversion,
Medication to maintain normal rhythm:amiodarone,
medication to control ventricular rate: calcium channel blockers, beta blockers,
Medication to reduce atrial thrombus: coumadin, Pradaxa, Xarelto, Eliquis,
Cardiac ablaton: burn places in heart
A. Fib Symptoms
Racing heartbeat, irregular Heart palpitations Dizziness Sweating Chest pain or pressure SOB Confusion Fatigue Reduced ability to exercise A. Fib may be occasional, persistent, or permantent FROM POOR CARDIAC OUTPUT
Associated causes of A flutter and A fib
COPD, CHF, Valvular heart disease, Chronic hypertension, Ischemic heart disease, MI
First Degree AV block
Normal rate, regular rhythm, one p wave before each QRS,
- PR prolonged and constant (longer than 0.20)
- usually no tx needed
Second Degree AV block- Wenkebach type 1
- Progressive prolongation of the PR interval until a Pwave is not conducted
- Patterns repeats itself
- it occurs when an abnormality in the AV junction delays or blocks conduction of some of the impulses through the AV node
Second Degree AV block- Mobitz type II
PR intervals: for conducted p waves, P-R intervals is consistent (normal or can have a 1st degree block), muliple p waves not followed by QRS wave
Mobitz type II result from
serious problem such as MI or ischemia, requires tx to improve cardiac output, pacemaker is indicated
3rd degree (complete) AV block
Normal everything, but no measurable PR intervals, heart must pace to maintain acceptable cardiac output
List one major complication/ risk of having Atrial fib.
Thrombi= must be on blood thinners, and emboli= stroke
Symptomatic Bradycardia
(Need IV access)
- HR is slow
- Pt has symptoms
- Symptoms due to slow HR
Bradycardia symptoms
Chest discomfort or pain, SOB, decrease LOC, Weakness, fatigue, light headed, dizziness, and presyncope or syncope similar to tachycardia