N250 DYSRHYTHMIAS EXAM QUESTIONS AND ANSWERS
WITH COMPLETE SOLUTIONS GRADED A++
dysrhythmia
include
- sinus bradycardia and tachycardia
- AV blocks
- atrial fibrillation
- ventricular asysytole
- premature atrial complexes (PACs) and premature ventricular complexes (PVCs)
- supra ventricular tachycardia
- ventricular tachycardia
- ventricular fibrillation
disorder of the electrical impulses within the heart that causes disturbances of the heart
rate, heart rhythm or both
may initially produce symptoms related to the hydrodynamic effect they cause, such as
a decrease in cardiac output
some dysrhythmias increase the risk of clot formation within the chambers of the heart
physiology review
no action potential on the exam
,the heart is both an electrical system and a pump
to work effectively the electrical system and pump must work together
electrical system stimulates muscle contraction and relaxation and coordinates the
forward flow of blood from the atria to the ventricles and out to the body.
every beat represents multiple ion shifts (action potential) across cell membranes that
initiates an electrical stimulus and cause muscle contraction.
Basic Electrophysiology
resting potential state cells are polarized and ready to accept an impulse
depolarization the cells receive and respond to an electrical stimuli (movement of
charged particles to make inside of cell positive)
repolarization movement of charged particles to make the cell negative again
absolute refractory period the heart cannot accept another impulse
relative refractory period a greater than normal impulse can cause electrical
discharged
like flushing the toilet: the time right after you flush the toilet and you jiggle the handle
and nothing happens, that's the absolute refractory period. the heart will not accept a
new pulse.
before the toilet bowl is done filling, you can hit that handle a little but harder than
normal and get it to flush. this is your relative refractory period.
,PROPERTIES OF CARDIAC CELLS
Automaticity - the ability to initiate a response
Excitability - the ability to respond to an impulse
Conductivity - the ability to transmit an impulse
Contractility - the ability to respond to an electrical impulse with a pump action
CONDUCTION SYSTEM
SA node (sinoatrial)
heart's primary pacemaker
- spontaneously generates impulses at a rate of 60-100 beats per minute
- Impulses move from the SA node through the atrial muscle which causes atrial
depolarization
- Reflected as a p wave on the ECG/EKG
- Atrial muscle contraction should follow blood should be pushed out of the atrium down
to the ventricle.
AV node (atrioventricular)
- Here the transitional cells cause impulses to slow down or be delayed before
proceeding to the ventricles. this is important ti remember when we talk about heart
blocks.
- This is represented by the PR segment on the ECG
- This delay allows the atria to contract and the ventricles to fill. lack of this delay time
, results in improper filling and thus decreased cardiac output.
Bundle of His
- Connects with the distal portion of the AV node and continues through the
intraventricular septum
- Divides off into right and left bundle branches
- the right goes to the right ventricle and the left to the left.
Purknje fibers
- Ends of the right and left bundle braches
- Responsible for the rapid conduction of electrical impulses throughout the ventricles
- Leads to ventricular depolarization and subsequent ventricular contraction
BASIC CARDIAC RHYTHM
WHAT IS AN ECG OR EKG (ELECTROCARDIOGRAM)?
ELECTROCARDIOGRAM
- Graphic representation (picture) of cardiac electrical activity
- Each phase of the cardiac cycle is reflected by specific waveforms
- The electrodes record waveforms that appear on the paper or monitor and represent
the electrical current.
- A lead provides one view of the heart's electrical activity
WITH COMPLETE SOLUTIONS GRADED A++
dysrhythmia
include
- sinus bradycardia and tachycardia
- AV blocks
- atrial fibrillation
- ventricular asysytole
- premature atrial complexes (PACs) and premature ventricular complexes (PVCs)
- supra ventricular tachycardia
- ventricular tachycardia
- ventricular fibrillation
disorder of the electrical impulses within the heart that causes disturbances of the heart
rate, heart rhythm or both
may initially produce symptoms related to the hydrodynamic effect they cause, such as
a decrease in cardiac output
some dysrhythmias increase the risk of clot formation within the chambers of the heart
physiology review
no action potential on the exam
,the heart is both an electrical system and a pump
to work effectively the electrical system and pump must work together
electrical system stimulates muscle contraction and relaxation and coordinates the
forward flow of blood from the atria to the ventricles and out to the body.
every beat represents multiple ion shifts (action potential) across cell membranes that
initiates an electrical stimulus and cause muscle contraction.
Basic Electrophysiology
resting potential state cells are polarized and ready to accept an impulse
depolarization the cells receive and respond to an electrical stimuli (movement of
charged particles to make inside of cell positive)
repolarization movement of charged particles to make the cell negative again
absolute refractory period the heart cannot accept another impulse
relative refractory period a greater than normal impulse can cause electrical
discharged
like flushing the toilet: the time right after you flush the toilet and you jiggle the handle
and nothing happens, that's the absolute refractory period. the heart will not accept a
new pulse.
before the toilet bowl is done filling, you can hit that handle a little but harder than
normal and get it to flush. this is your relative refractory period.
,PROPERTIES OF CARDIAC CELLS
Automaticity - the ability to initiate a response
Excitability - the ability to respond to an impulse
Conductivity - the ability to transmit an impulse
Contractility - the ability to respond to an electrical impulse with a pump action
CONDUCTION SYSTEM
SA node (sinoatrial)
heart's primary pacemaker
- spontaneously generates impulses at a rate of 60-100 beats per minute
- Impulses move from the SA node through the atrial muscle which causes atrial
depolarization
- Reflected as a p wave on the ECG/EKG
- Atrial muscle contraction should follow blood should be pushed out of the atrium down
to the ventricle.
AV node (atrioventricular)
- Here the transitional cells cause impulses to slow down or be delayed before
proceeding to the ventricles. this is important ti remember when we talk about heart
blocks.
- This is represented by the PR segment on the ECG
- This delay allows the atria to contract and the ventricles to fill. lack of this delay time
, results in improper filling and thus decreased cardiac output.
Bundle of His
- Connects with the distal portion of the AV node and continues through the
intraventricular septum
- Divides off into right and left bundle branches
- the right goes to the right ventricle and the left to the left.
Purknje fibers
- Ends of the right and left bundle braches
- Responsible for the rapid conduction of electrical impulses throughout the ventricles
- Leads to ventricular depolarization and subsequent ventricular contraction
BASIC CARDIAC RHYTHM
WHAT IS AN ECG OR EKG (ELECTROCARDIOGRAM)?
ELECTROCARDIOGRAM
- Graphic representation (picture) of cardiac electrical activity
- Each phase of the cardiac cycle is reflected by specific waveforms
- The electrodes record waveforms that appear on the paper or monitor and represent
the electrical current.
- A lead provides one view of the heart's electrical activity
