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285 Cards in this Set

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What is an Isoelectric Line?
The absence of any electrical impulse, on an ECG (EKG)
What is Artifact?
Deflection on the ECG produced by factors other than the heart's electrical activity.
Explain Negative and Positive Deflection
Negative is the impulses that travel away from the lead.
Positive is the impulses that travel toward the lead.
What are Bipolar Leads?
ECG leads applied to the arms and legs that contain 2 electrodes of opposite (positive and negative) polarity: Leads I, II, III
What is Einthoven's Triangle?
The triangle around the heart formed by the bipolar limb leads.
RA (-,-)
LA (+,-)
LL (+,+)
What is the most common lead?
Lead II, The LL, it acts as a camera watching the hearts activity come toward it and away from it. Although it states LL (Left Left) it can be placed on the lower torso.
Which Lead picks up the activity from the Bachmanns bundles?
lead I, it reflects lateral activity from the SA node to the Atrias.
What are Unipolar Limb Leads?
ECG Leads applied to the arms and legs, consisting of one polarized (positive) electrode and a nonpolarized reference point that is creaated by the ECG machine combining two additional electrodes; also called augmented limb leads; leads aVR, aVL and aVF
What are augmented limb leads?
Another term for unipolar limb leads, reflecting the fact that the ground lead is disconnected, which increases the amplitude of deflection on the ECG tracing.
What are precordial (chest) leads?
ECG leads applied to the chest in a pattern that permits a view of the horizontal plane of the heart; leads V1, V2, V3, V4, V5, and V6.

All leads are unipolar
How is the time graphed on ECG paper
25mm per second. Each small square box on graph paper represents a 1mm squared. Each vertical line: 0.4sec = 40ms The big box represents 5mm squared. (5mm/sec). Time moves on the horizontal but is measured on the vertical line.
How is Amplitude measured
each small box represents 0.1 mv.

Each large box represents .5mv.
Standard calibration = 1mv (2 large boxes)
What is PQRST Segment?
ECG components.
P wave
QRS complex
T wave
U wave
What does the QRS complex represent?
The ventricular depolarization.
What does the T wave represent?
Ventricular repolarization
What is the PR interval?
Should be normally 0.12 - 0.20 seconds
(between 3 small - 5 small boxes)
What is the QRS interval?
Should be 0.08 - 0.12 Seconds
What is the Q - T Interval?
0.33 - 0.42 Seconds (not really used to interpret ECG)
What is the S-T Segment?
It is associated with Myocardial infarctions.
Depression normally seen with ischemia.
Elevation normally seen with MI.
5 step rule for interpreting a rhythm strip
1.Rate
2.Rhythm
3.p waves
4.PRI
5.QRS
How to analyze rate
6 second method (most common)
heart rate calculator rulers
R-R interval
Triplicate Method
How to analyze rhythm
regular
Occasional irregular
Regulary Irregular
Irregularly Irregular
How to analyze a P wave?
Are P waves present?
Are the P Waves regular?
Is there 1 P wave for each QRS complex?
Are the P waves upright or inverted? (they should always be upright and no inverted)
Do all the P waves look alike?
P-R interval
Represents repolarization on atria and beginning of depolarization.
How do you analyze the QRS complex
Should be less than 0.12.
Do all the QRS complexes look alike?
What is the QRS duration?
Characteristics of a normal sinus rhythm
Rate: 60-100
Rhythm: Regular
P waves: Normal, upright, only before each QRS complex.
PR Interval: 0.12-0.20 seconds
QRS Complex: Normal, duration of ,0.12 seconds
What are some causes of dysrhythmias?
MI
trauma to myocardium
ANS imbalance
Distention of the chambers of the heart.
Blood gas abnormalities.
Electrolyte imbalances.
Drug Effects
Electrocution
Hypothermia
CNS Damage
Idiopathic Events
Normal Occurences
What is Ectopic Foci?
Ectopic beat. A beat that happens outside its normal pathway. Like an extra beat.
Classification of Dysrhythmias
Nature of Origin
magnitude
severity
Site of Origin
What are the 4 sinus dysrhythmias?
Sinus Bradycardia
Sinus Tachycardia
Sinus Dysrhythmia
Sinus Arrest
What are the characteristics of Sinus Bradycardia?
Rate <60
Rhythm: regular
Pacemaker Site: SA Node
P Waves: Upright & Normal
PRI: Normal
QRS: Normal

(it is not a normal sinus rhythm, but it IS a sinus rhythm)
What are the characteristics of Sinus Tachycardia?
Rate: >100
Rhythm: Regular
Pacemaker site: SA Node
P Waves: Upright & Normal
PRI: Normal
QRS: Normal
What are the characteristics of Sinus Dysrhythmia?
Rate:60-100
Rhythm: Irregular (there will be a delay without a pattern)
Pacemaker Site: SA Node
P Waves: Upright & Normal
PRI: Normal
QRS: Normal
What are the characteristics of Sinus Arrest? (dropped sinus beat)
Rate: Normal to slow
Rhythm: Irregular
Pacemaker Site: SA Node
P Waves: Upright & Normal
PRI: Normal
QRS: Normal
What are the characteristics of Atrial Tachycardia?
Rate: not usually Normal
Rhythm: Slightly irregular
PaceMaker Site: Varies among the SA Node, atrial tissue, and AV junction
P Waves: Variable or absent
PRI: Varies depending on source of impulse
QRS: Normal
What are the characteristics of Paroxysmal Supraventricular tachycardia (svt)?
Rate: 150-250
rhythm: regular
Pacemaker Site: Atrial (outside SA node)
P Waves: Often buried in preceding t waves
PRI: Usually normal
QRS: Usually Normal
What is Paroxysmal?
Immediate onset
What are the characteristics of Atrial Flutter?
Rate: Atrial rate 250-350, Ventricular rate varies
Rhythm: Usually Regular
Pacemaker Site: Atrial (outside SA node)
P Waves: F waves are present
PRI: Usually normal
QRS: Usually normal
What are the characteristics of Atrial Fibrillation?
Rate: 350-50 Ventricular rate varies
Rhythm: irregularly irregular
Pacemaker Site: atrial (outside SA Node)
P Waves: None discernable
PRI: None
QRS: Normal
What is Anastomosis?
The communication between two or more vessels.
What is collateral circulation?
a protective mechanism that provides an alternative path for blood flow in case of a blockage. Analogous to a river's developing tributaries to reach a larger body of water.
What is Poiseuille's Law?
a law of physiology stating that blood flow through a vessel is directly proportional to the radius of the vessel to the 4th power.
What is the tunica intima?
The innermost lining of the arteries and veins. It is a single cell layer thick.
What is the tunica media?
It is the middle layer of Arterlies and veins. It consists of elastic fibers and muscle. It gives blood vessels their strength and recoil. It is much thicker in arteries than in veins.
What is the tunica adventitia?
It is the outermost layer of the Arteries and veins. A fibrous tissue covering. It gives the vesels strength to withstand the pressures generated by the hearts contractions.
What is the cavity inside a vessel called?
The lumen.
What is the cardiac Cycle?
The period of time from the end of one cardiac contraction to the end of the next
What is Diastole?
The first phase of the cardiac cycle (the relaxation phase) The period of time when the myocardium is relaxed and cardiac filling and coronary perfusion occur
What is systole?
Th eperiod of the cardiac cycle when the myocardium is contracting
What is ejection fraction?
Ratio of blood pumped from the ventricle to the amount remaining at the end of diastole. The normal ventricle ejects about 2/3 of the blood is contains at the end of diastole.
What is Stroke Volume?
The amount of blood ejected by the heart in one cardiac contraction. It varies between 60 - 100 mL, with average being 70 mL.
What is atrial Systole?
It is the first contraction occuring relatively quick, this Atrial Kick boosts cardiac output.
What is Preload?
The pressure within the ventricles at the end of diastole; commonly called the end-diastolic volume.
What is the "Starlings Law of the heart"?
Law of physiology staating that the more the myocardium is stretched, up to a certain amount, the more forceful the subsequent contraction will be.
What is Afterload?
the resistance against which the heart must pump.
What 3 Factors does stroke volume depend on?
preload, Cadiac contractility and afterload.
What is the force and amount of each contraction influenced by?
Preload
What is Cardiac Output?
The amount of blood pumped by the heart in 1 min.

SVxHR=CO

The average CO is 5L/min or 5,000mL/min
How is Blood Pressure Calculated?
BP=COxSVR
What is the Cardiac Plexus?
It is a network of nerves at the base of the heart. The point where the sympathetic nervous system innervates the heart.
Trace the Sympathetic nerves from its origin.
The nsympathetic nerves arise from the thoracic and lumbar regions of the spinal cord, then leave the spinal cord and form the sypathetic chain, which runs along the spinal column. The cardiac plexus arises in turn from ganglia in the sympathetic chain and innervates both the atria and ventricles.
What is the chemical neurotransmitter for the sympathetic nervous system & the cardiac plexus?
norepinephrine. its release increases HR and contractile force, primarily through its actions on beta receptors.
What are the two principal types of receptors for the sympathetic nervous system?
Alpha and Beta
What are Alpha receptors?
They are receptors that are located in the peripheral blood vessels and are responsible for vasoconstriction.
What are Beta₁ Receptors?
They are primarily located in the heart, increase the HR and contrctility
What are Beta₂ Receptors?
They are principally located in the lungs and peripheral blood vessels, cause bronchodilation and peripheral vasodilation.
What is the general MOA for beta blockers?
They slow the HR and lower BP by blocking Beta₁ receptors, whose job is to increase HR and contractility.
What is the Vagus Nerve?
The 10th cranial nerve. Parasympathetic control of the heart occurs through the Vagus nerve. The vagal nerve fibers primarily innervate the atria, althou some innervate the upper ventricles.
What is the chemical neurotransmitter for the parasympathetic nervous system?
Acetylcholine. Its release slows both the HR and atroventricular conduction.
What is the Valsalva maneuver?
Forces expiration against a closed glottis, which can occur when lifting heavy objects.
Name three things that can stimulate the vagus nerve
The Valsalva maneuver, Carotid sinus massage, distention of the urinary bladder.
What is chronotropy?
Pertaining to autonomic control of the heart rate.
What does a negative chronotropic agent do?
It decreases the heart rate.
What is Inotropy?
Pertains to the autonomic control of of cardiac contractile force. The strength of the contraction.
What does a positive inotropic agent do?
And a negtive inotropic agent?
Positive: strengthens the cardiac contraction.
Negative: weakens it.
What is Dromotropy?
Pertains to the autonomic control of the rate of nervous impulse conduction.
What does a positive dromotropic agent do?
And a negative agent?
positive: speeds impulse conduction
Negative: slows conduction
What are the electrolytes that affect cardiac function?
sodium (Na+)
calcium (Ca++)
potassium (K+)
chloride (Cl-)
magnesium (Mg++)
What is the soldium role in cardiac function?
Plays a mojor role in depolarizing the myocardium.
What is the Calcium role in cardiac function?
calcium takes part in myocardial depolarization and myocardial contraction.
What is Hypercalcemia and how does it affect the heart?
hypercalcemia is too much calcium in the blood, can result in increased contractility.
What is Hypocalcemia and how does it affect the heart?
A condition where too little calcium if found in the blood. It is associated with decreased myocardial contractility and increased electrical irritabiltiy.
What role does Potassium play on the heart?
Potassium infuences repolarization.
What is hyperkalemia and how does it affect the heart?
Hyperkalemia is too much Potassium in the blood, it results in deceased automaticity and conduction
What is hypokalemia and how does it affect the heart?
A condition where too little Potassium is found in the blood, resulting in increased irritability.
What are intercalated disks?
Specialized bands of tissue inserted between myocardial cells that increase the rate in which the action potential is spread from cell to cell.
What is "syncytium"?
group of cardiac muscle cells that physiologicall function as a unit.
The heart is comprised of what three types of cardiac muscle?
Atrial
Ventricular
Specialized excitatiry and conductive fibers
Where are intercalated disks located?
They are located within the atrial and ventricular muscle fibers.
At what rate do intercalated disks conduct electrical impulses, and how does this affect the heart muscle?
400 times faster than the standard cell membrane. This increased speed results in the cardiac muscle cells to act as a unit "syncytium".
Name the two heart Syncytia.
The atrial syncytium
The ventricular syncytium
How does the atrial syncytium contract?
The atrial syncytium contracts from the superior to inferior, so that the atria express blood to the ventricles.
How does the ventricular syncytium contract?
The ventricular syncytium contracts from the inferior to the superior, expelling blood from the ventricles into the aorta and pulmonary arteries.
How are impulses conducted from the atria to the ventricles?
Through the atrioventricular (AV)bundle.
Explain the cardiac muscle "All or None" principle?
if a single muscle fiber becomes depolarized, the action potential will spread through the whole syncytium. Stimulating a single atrial fiber will thus completely depolarize the atria, same for the ventricles.
What is cardiac depolarization?
A reversal of charges at a cell membrane so that the inside of the cell becomes positive in relation to the outside;the opposite of the cell's resting state in which the inside of the cell is negative in relation to the outside. muscle contraction follows depolarizaton.
What is resting potential?
The normal electrical state of cardiac cells, which is approximately 90mV (millivolts)
What is action potential?
The stimulation of myocardial cells, as evidenced by a change in the membrane electrical charge, that subsequently spreads across the myocardium. This charge is so strong that it gives the inside of the cell a positive charge approx. 20mV greater than the outside.
What is repolarization?
The return of a muscle cell to its preexcitation resting state.
What is excitabilty?
Abiltiy of the cells to respond to an electrical stimulus.
What is conductivity?
The cells can propagate the electrical impulse from one cell to another
What is Automaticity?
Pacemaker cell's capability to self depolarize. The cell with the fastes rate of discharge becomes the hearts pacemaker.
What is the SA node?
The sinoatiral node. Located high in the right atrium, considered the highes cell in the conductive system with the fasted rate of automaticity.
What is contractility?
The cardiac cell's ability to contract.
What is the internodal atrial pathway?
It connects the SA node to the AV node. It conducts the depolarization impulse to the atrial muscle mass through the atria to the AV junction then to the AV node and on to the AV fibers.
What is the AV Junction?
The "gatekeeper". Slows the impulse and allows the ventricles time to fill.
What is the bundle if His?
The AV fibers form the bundle of His in the ventricles. It subsequently divides into the right and left bundle branches.
What is the Purkinje system?
The left and right bundle branches turn into the Purkinje system which spreads across the myocardium.
What is a rhythm strip?
An EKG printout
What is an electrocardiogram?
(ECG) The graphic recording of the hearts electrical activity. It may be displayed either on paper or on an oscilloscope.
What is artifact?
The deflection on the ECG produced by factors other than the heart's electrical activity
What does the EKG not tell you?
The hearts pumping ability. You must elvaluate by pulse and BP.
How do positive impulses appear on an EKG?
It appears as an upward deflection
How do negative impulses appear on an EKG?
It appears as a downward deflection.
What is an isoelectric line?
a flat line representing the absence of any electrical impulse.
If the patient is diaphoretic, how do you apply the electrodes?
Wipe the skin and apply tincture of bensoin before applying the electrodes.
What is a "lead"
A pair of electrodes.
What are the 3 types of EKG leads?
Bipolar
Aumented
Precordial
What are bipolar leads?
Most frequently used EKG leads applied to the arms and legs that contain two electrodes of opposite polarity; leads I,II,and III
Any electrical impulse moving toward a positive electrode will result in what?
It will cause a positive (upward deflection) on the EKG strip.
Any electrical impulse moving toward the negative electrode will result in what?
It will cause a negative (downward deflection)
What is the Einthovens triangle?
The triangle around the heart formed by the bipolar limb leads.
What is the leads axis?
The direction from the negative to the positive electrode is the axis. Each lead shows a different axis of the heart.
What are the lead axis' in Einthovens triange?
lead I (top)= 0 degrees
lead II (right) = 60 degrees
lead III (left) = 120 degrees
What are augmented limb leads?
another term for unipolar leads, reflecting the fact that the ground lead is disconnected, which increases the amlitude of deflection on the EKG tracing.
What are Unipolar limb leads?
EKG leads applied to the arms and legs, consisting of one pos. electrode and a nonpolarized reference point that is created by the EKG machine combining two additional electrodes; also called augmented limb leads; leads aVR, aVI, aVF
What are precordial (chest) leads?
EKG leads applied to the chest in a pattern that permits a view of the horizontal plane of the heart; leads V1, V2, V3, V4, V5, V6
Why is lead II the most common lead used?
Most of the hearts electrical current flows toward its positive axis. It gives the best view of the EKG waves and best depicts the conduction system's activity.
What is the standard speed of the EKG paper?
25 mm/sec
What are the EKG paper graph measurements?
1 small box = 0.04 sec. (1mm2)
1 large box = 0.20 sec (5 mm2)
15 large boxes = 3 sec
30 large boxes = 6 sec
What is the P wave
The first component of the EKG, the P wave corresponds to atrial depolarization. On lead II it is a positive rounded wave before the QRS complex
What is the QRS complex?
Reflects ventricular depolarization. The Q wave is the first negative deflection. The R wave is the first positive deflection, the S wave is the first negative deflection after the R wave. Not all wave are always present.
What is the T wave?
reflects the repolarization of the ventricles. Normally positive in lead II, it is rounded and usually moves in the same direction as the QRS complex.
What is the U wave?
Follow T waves and are usually positive. U waves may be associated with electrolyte abnormalities or they may be a normal finding.
What is the PRI?
PR Interval: distance from the beginning of the P wave to the beginning of the QRS complex. Represents the time the impulse takes to travel from the atria to the ventricles.
What is the QRS interval?
The distance from the first deflection of the QRS complex tothe last. It represents the time necessary for ventricular depolarization.
What is an Occasionally irregular rhythm?
Only one or two R-R intervals on the strip are irregular.
What is a Regular Irregular Rhythm?
A patterned irregularity or group beating.
What is an Irregularly Irregular Rhythm?
The is no relationship among R-R intervals.
What is the definition of a normal sinus rhythm?
The normal heart rhythm, no abnormalities noted.
What is a dysrhythmia?
Any deviation from the normal electrical rhythm of the heart
What is an Arrhythmia?
The absence of cardiac electrical activity; often used interchangeably with dysrhythmia
How do you analyze the P waves?
P waves reflect atrial polarization. Answer the following questions:
Are P wave present?
Are the P waves regular?
Is there 1 P wave for every QRS?
Are the P waves Upright?
Do all the P waves look alike?
How do you analyze the PRI?
The PRI represents the time needed for atrial depolarization and conduction of the impulse to the AV node. Normally the time should show as 3-5 small boxes, any deviation is an abnormal finding.
How do you analyze the QRS complex?
The QRS complex represents ventricular depolarization. Answer these questions:
Do all of the QRS complexes look alike?
What is the QRS duration? Remember, anything longer than 0.12 sec (3 small boxes) is abnormal.
What is "antegrade"?
Antegrade means forward, The depolarization impulse is normally antegrade.
What is "retrograde"?
Retrograde means backwards. In certain dysrhythmia's, the depolarization is retrograde.
What is enhanced automaticity?
This condition results when ectopic foci automatically depolarize, producing ectopic beats.
What is an ectopic beat?
Cardiac depolarization resulting from depolarization of ectopic focus. PVC's and PAC's are examples of ectopic beats. They can intermittent or sustained.
What is Ectopic Focus
Nonpacemaker heart cell that automatically depolarizes. pl. ectopic foci
What is reentry?
It occurs when ischemia or another disease process alters two branches of a conduction pathway, slowing conduction in one branch and causing a unidirectional block in the other. An antegrade depolarization wave travels slowly through the branch with ischemia and is blocked in the branch with the unidirectional block, it is then conducted retrograde back to the branches origin. The tissue is no longer refractory, and stimulation occurs again. This can result in rapid rhythms such as PSVT or A-Fib.
What common dysrhythmias originate in the SA node?
Sinus bradycardia
Sinus tachycardia
Sinus dysrhythmia
Sinus arrest
What to dysrhythmias originating in the SA node often result from?
They often result from changes in automaticity tone. however, disease can exist in the SA node itself.
What are some of the common causes of Sinus tachycardia?
Exercise
Fever
Anxiety
Hypovolemia
Anemia
Pump Failure
Increased Sympathetic Tone
Hypoxia
Hyperthyroidsim
What are the Rules of interpretation?
Rate
Rhythm
Pacemaker Site
P Waves
PRI
QRS complex
What is the pharmacological treatment for Sinus Bradycardia?
Tx: Is gennerally unnecessary unless hypotension or ventricular irritability is present. It Tx is required: adm. 0.5mg bolus of Atropine Sulfate, repeat q 3-5min until satisfactory rate or reached max dose of 3.0mg.
What is the treatment for Sinus Tachycardia?
Tx is directed at the underlying cause. Hypovolemia, fever, hypoxia etc. should be corrected.
What is the treatment for sinus dysrhythmia?
typically, none required.
Define Sinus Bradycardia
Results from slowing of the SA node.
define Sinus Tachycardia
results from an increased rate of the SA node discharge
Define Sinus disrhythmia
Often results from a variation of the R-R interval. Is often a normal finding and is sometimes related to the respiratory cycle and changes in the intrathoracic pressure.
Define Sinus Arrest
occurs when the sinus node fails to discharge, resulting in short periods of cardiac standstill. This standstill can persist until pacemaker cells lower in the conductive system discharge or until the sinus node resumes discharge.
What are escape beats?
Heartbeat that occurs after a prolonged pause, or failure of the SA node to stimulate the heart to contract.
What are some common dysrhythmias originating in the atria?
Wandering atrial pacemaker
Multifocal atrial tachycardia
premature atrial contraction
Paroxysmal supraventricular tachycardia
What are the characteristics of a Wandering atrial Pacemaker?
Rate: Usually normal
Rhythm: Slightly irregular
Pacemaker Site: Varies among the SA node, atrial tissue, and the AV junction
P Waves: morphology changes from beat to beat; P waves may dissapear entirely
PRI: Varies
QRS: normal
Define Wandering Atrial Pacemaker
Also called ectopic tachycardia. The passive transfer of pacemaker sites from the SAnode to other latent pacemaker sites, causing variation in R-R interval and P wave morphology.
Define Multifocal Atrial Tachycardia
(MAT) Usually seen in acutely ill patients. Significant pulmonary disease is seen in about 60% of these patients. Three different P waves are noted indicating various ectopic foci.
How is Wandering Atrial Pacemaker treated?
if the patient is asymptomatic, observation is all that is needed. If the pt. is symptomatic consider adenosine or verapamil
How is MAT treated?
treatment of underlying medical disease usually resolves the dysrhythmia.
What is a noncompensatory pause?
A pause following an ectopic beat where the SA node is depolarized and the underlying cadence of the heart is interrupted. Usually seen in PAC
Define premature Atrial Contractions
(PAC) result from a single electrical impulse originating in the atria outside the SA node, which in turn causes a prematures depolarization of the heart before the next expected sinus beat.
Define Paroxysmal Supraventricular Tachycardia
(PSVT) Occurs when rapid atrial depolarization overrides the SA node. It may have a sudden onset that lasts minutes to hours then terminate abruptly.
What is a bruit?
the sound of the turbulent blood flow through a vessel; usually associated with artherosclerotic disease.
Define Atrial Flutter
results from a rapid atrial reentry circuit and an AV node that physiologically cannot conduct all impulses through to the ventricles.
Define A-Fib
results from multiple areas of reentry within the atria or from multiple ectopic foci bombarding an AV node that physiologically cannot handle all of the incoming impulses. AV conduction is random and highly variable.
The anterior decending artery and the circumflex artery supplies bllod to what part of the heart?
The left ventricle, interventricular septum, part of the right ventricle, and the heart's conduction system.
What is the tunica adventicia?
The fibrous covering layer of the vessel.
The normal cardiac output is approximately what volume?
5,000mL
positive inotropic and chronotropic effects result from what?
Stimulation of the heart by the sympathetic nervous system.
What is the normal duration of the QRS interval?
0.8-0.12 sec
Which atrial dysrhythmia is often an indication od serious underlying medical disease?
Multifocal Atrial tachycardia
(MAT)
Which atrial dysrhythmia has a characteristic sawtooth shaped P wave?
A-Fib
What is the diagnostic finding for first degree AV block on an EKG?
A P-R interval that is longer than 0.20 seconds
Which element of the EKG is normally between 0.8 and 0.12 seconds?
The QRS interval
No relationship among R-R intervals would classify which dysrhythmia?
Irregularly irregular
An R-R interval that varies with respirations indicates which dysrhythmia?
Sinus Dysrhythmia
What is the cheif difference between type I and type II second degree AV block?
The pattern of lengthening P-R interval before the blocked impulse in Type I second-degree AV block
The apex of the heart lies at approximately the level of the ...
Fourth Rib
left and Right Coronary arteries arise from the...
aorta
actual time sequence between ventricular contractions and ventricular relaxation is called...
Cycle
Resistence against which the heart must pump is called...
Afterload
Peripheral Vascular Resistance is determined by...
Vasocontriction and Vasodilation
Nerve endings in the SNS are called...
Adrenergic
Nerve endings in the PNS are called...
Cholinergic
Vasoconstriction and increased BP are effects of...
Alpha
increased HR and increased contractility are effects of...
Beta1
What are Myocardial working cells responsible for?
Generating contraction of heart muscles
What does physical contraction of myocardial tissues actually generate?
Blood flow
What does Threshold refer to?
The point at which a stimulus will produce a cell response
What cation returns to the inside of the cell at the end of cardiac depolarization?
Potassium
What cation returns to the outside of the cell at the end of cardiac depolarization?
Sodium
What is the absolute refractory period?
Corresponds with the beginning of the QRS complex to the peak of the T wave.
What is the conduction pathway that lies on top of the interventricular septum?
bundle of His
What is the term that defines the graphic representation of electrical activity of the heart?
Electrocardiogram
How many positive and negative leads do bipolar leads have?
One positive and One negative
How is time measured on the graph paper?
on the verticle line
How is amplitude measured on the graph paper?
On the horizontal line
The normal PRI is 0.12-0.20 sec. When there is a problem with progression of the impulse outside the normal route, this is indicated by a PRI of...
less than 0.12 sec.
What is a atrioventricular block?
AV block. The electrical impulse is slowed or blocked as it passes through the AV node.
What 2 important physiological purposes does the AV Junction serve?
1. It slows impulse to allow for atrial emptying and ventricular filling.
2. It serves as a backup pacemaker if the SA node or cells higher in the conductive system fail to fire.
What are transistional fibers?
The internodal fibers that blend to form the AV junction.
What is a compensatory pause?
The pause following an ectopic beat where the SA node is unnafected and the cadence of the heart is uninterrupted.
What is an AV block?
A delay or interruption between the atria and the ventricles.
How are AV blocks classified?
They can be classified according to the site or degree of the block. Blocks may occur at the AV node, the bundle of His, and below the bifurcation of the bundle of His.
What are the "traditional classification" of AV blocks?
1st degree
Type 1 2nd degree (Mobitz I or Wenckemach)
Type II 2nd Degree (Mobitz II, or infranodal)
Third degree AV Block (CHB)
What is a first degree AV block?
A delay in conduction at the level of the AV node rather that an actual block. The underlying rhythm must also be identified.
What is the most common cause of an AV block?
Ischemia
What are the Rules of interpretation for a 1st degree AVB?
Rate: depends on the underlying rhythm
Rhythm: usually regular, can be slightly irregular.
Pacemaker site: SA node or Atria
P waves: Normal
PRI: >0.20
QRS: usually less than 0.12 sec; may be bizarre in shape if conductive system disease exists in the ventricles.
What is the treatment for a 1st degree block?
No treatment is required except observation, unless the HR drops significantly.
What is a Type I Second-Degree AVB?
Also called Mobitz I or Wenckebach. An intermittent block at the level of the AV node. It produces a characteristic cyclic pattern in which the PRI become progressively longer until and impulse is blocked.
What are the common ratio of conduction for Type I Second Degree AVB?
5:4, 4:3, 3:2 or 2:1
What are the Rules of interpretation for Type I second degree AVB?
Rate: Atrial rate is unaffected, The ventricular rate may be normal or slowed
Rhythm: Atrial rhythm is typically regualr, ventricular rhythm is irregular because of the nonconducted beat.
Pacemaker site: SA node or atria
P waves: normal, some P waves are not followed by QRS
PRI: becomes progressively longer until the QRS complex is dropped, then the cycle repeats.
QRS complex: usually less than 0.12 sec; may be bizarre in shape if conductive system disease exists in the ventricles.
What is Type II Second degree AV Block?
Also called second degree Mobitz II or infranodal. An intermittent block characterized by P waves that are not cunducted to the ventricles, but without associated lengthening of the PRI before the dropped beat.
What is the common ratio of conduction for Type II second degree AVB?
4:1, 3:1, 2:1 The ratio may be constant or may vary
What are the rules of interpretation for Typre II second degree AVB?
Rate: Atrial rate is unaffected, ventricular rate is usually bradycardia.
Rhythm: regular or irregular, depending on whether the conduction ration is constant or varied.
Pacemaker site: SA node or atria.
P waves: normal, some P waves are not followed by QRS complexes
PRI:constant for conducted beats; may be greater than 0.21 sec
QRS complex: may be normal; however it is often greater than 0.12 sec because of abnormal ventricular depolarization sequence.
What is a third degree AVB?
A complete block (CHB). The absence of conduction between the atria and the ventricles resulting from complete electrical block at or below the AV node.
What are the rules of interpretation for Third degree AVB
Rate: atrial rate is unaffected. Ventricular rate is 40-60 if the escape pacemaker is junctional, less than 40 if the escape pacemaker is lower in the ventricles.
Rhythm: both atrial and ventricular rhythms are usually regular
Pacemaker site: SA node and AV junction or ventricle
P waves: normal. P waves show no relationship to the QRS complex, often falling within the T wave and QRS complex.
PRI: no relationship between P waves and R waves.
QRS complex: greater than 0.12 sec if pacemaker is ventricular; less than 0.12 sec if pacemaker is junctional
What common features do all dysrhythmias originating in the AV junction have?
Inverted P waves in Lead II
PRI less than .12
Normal QRS complex duration
What are premature junctional contraction?
PJCs result from a single electrical impulse originating in the AV node that occurs before the next expected sinus beat.
What is a compensatory pause?
The pause following an ectopic beat where the SA node is unaffected and the cadence of the heart is uninterrupted.
What are the rules of interpretation for PJC?
Rate: depends on the underlying rhythm
Rhythm: depends on the underlying rhythm usually regular except for the PJC
Pacemaker site: ectopic focus in the AV junction
P wave: inverted, may appear before or after the QRS, can be masked by the QRS or absent
PRI: if the P wave occurs before the QRS complex, the PRI will be less than .12, if the P wave occurs after the QRS complex, then technically it is a R-P interval.
QRS: usually normal, may be greater than .12 if the PJC is abnormally conducted through partial refractory ventricles
What is a Junctional escape Rhythm?
A dysrhythmia that results when the rate of the primary pacemaker, usually the SA node is slower than that of the AV node. The AV node then becomes the pacemaker.
What is the AV node's intrinsic rate?
40-60 bpm
What are the Rules of interpretation for Junctional escape Rhythm?
Rate: 40-60
Rhythm: Irregular in single junctional escape; regular in junctional escape rhythm.
Pacemaker site: AV junction
P Waves: inverted; may appear before or after QRS
PRI: If the P wave occurs before the QRS, the PRI will be <0.12. If the P wave occurs after the QRS, it is a P-R interval
QRS: Usually normal; may be greater than 0.12 sec.
What is the clinical significance of a junctional escape beat?
The slow HR can decrease cardiac output, possibly precipitating angina or other problems.
What is an Accelerated Junctional Rhythm?
Results from increased automaticity in the AV junction, causing the AV junction to discharge faster than its intrinsic rate.
What are the rules of interpretation for Accelerated Junctional Rhythm?
Rate: 60-100
Rhythm: Regular
Pacemaker Site: AV junction
P Waves: inverted; may appear before or after the QRS; P waves may be masked by the QRS or be absent.
PRI: If the P wave occurs before the QRS, the PRI will be <0.12, if it occurs after the QRS, it is an R-P interval.
QRS: Normal
What is Paroxysmal Junctional Tachycardia?
Develops when rapid AV junctional depolarization overrides the SA node. It often occurs in paroxysms. May also be called PVST.
What is Paroxism?
Sudden Onset.
What are the Rules of interpretation for Paroxysmal Junctional Tachycardia?
Rate: 100-180
Rhythm: Characteristically regular, except at onset and termination of paroxysms.
Pacemaker Site: AV junction
P Waves: Inverted (if present) They can occur before, during or after the QRS.
PRI: If the P waves occur before the QRS, the PRI will be <0.12
QRS: Normal
What is a ventricular escape beat?
Also called an idioventricular rhythm. Results either when impulses from higher pacemakers fail to reach the ventricles or when the discharge rate of higher pacemakers becomes less than the ventricles.
What are the rules of interpretation for Idioventricle rhythm?
Rate: 15-40
Rhythm: Irregular in a single ventricular escape complex. Vantricular escape rhythms are usually regular unless pacemakers site is low in the ventricular conductive system.
Pacemaker Site: Ventricle
P waves: none
PRI: none
QRS: greater than 0.12 sec and bizarre in morphology
What is an accelerated idioventricular rhythm?
An abnormally wide ventrular dysrhythmia the usually occurs during an AMI. It is a subtype of ventricular escape rhythm. Typically the rate is 60-110 Beats per minute.
What is a premature ventricular contraction?
A single ectopic impulse arising from irritable focus in either ventricle that occurs earlier than the next expected beat.
What is an interpolated beat?
A PVC that falls between two sinus beats without effectively interrupting this rhythm.
What is a coupling interval?
Distance between the preceding beat and the PVC.
What is a unifocal PVC?
If more than one PVC occurs, and each PVC has the same morphology, omplying one pacemaker site.
What is a multifocal PVC?
If more than one PVC occurs, and each PVC has different morphologies implying more than one pacemaker site.
What is Bigeminy?
Every other beat is a PVC
What is Trigeminy?
Every third beat is a PVC
What is Quadrigeminy?
Every fourth beat is a PVC
What are Repetitive PVC?
Two consecutive PVC without a normal complex in between. They can occur in groups of two or Three. More than three consecutive PVC are considered ventricular tachycardia.
What is a couplet?
A group of two repetitive PVC's
What is a triplet?
A group of three repetitive PVC's.
What can happen if PVC fall between the relative refractory period?
They can trigger dysrhythmias such as V-Fib.
What is the R on T phenomenon?
When PVC's fall within the relative refractory period
What are the rules of interpretation for PVCs?
Rate: depends on underlying rhythm
Rhythm: interrupts regularity of underlying rhythm
pacemaker site: Ventricle
P waves: none; however, interpolated P waves sometimes appear before a PVC
PRI: none
QRS: greater than 0.12 sec and bizarre in morphology.
What is the Lown grading system for premature beats?
Grade 0: No premature beats
Grade 1: <30 per hour
Grade 2: >30 per hour
Grade 3: Multifocal
Grade 4: Repetitive PVC
Grade 5: R on T phenomenon
What is Salvos?
A run of three or four PVC
What is ventricular tachycardia?
VT. Consists of three or more ventricular complexes in succession at a rate od 100 beats per min or more. This rhythm overrides the hearts pacemaker, and the atria and ventricles are asynchronus.
What is monomorphic VT?
The complexes all appear the same
What is polymorphic VT?
The complexes have different sizes and shapes. i.e. Torsades de pointes.
What are the Rules of interpretation for VT?
Rate: 100-250
Rhythm: Usually regular (can be slightly irregular)
Pacemaker site: If present, not associated with the QRS complexes.
PRI: none
QRS: greater than 0.12 sec and bizarre in morphology.
What is Torsades de Pointes?
A polymorphic ventricular tachycardia that differs in appearance and cause from VT in general. Most commonly caused by the use of certain antidysrhythmic drugs. The morphology of the QRS varies from beat to beat.
What is ventricular Fibrillation?
A chaotic ventricular rhythm usually resulting from the presence of many reentry circuits within the ventricles. There is no ventricular depolarization or contractions.
What are the rules of interpretation for VFib?
Rate: no organizes rhythm
Rhythm: no organized rhythm
Pacemaker Site: numerous ectopic foci
P waves: usually absent
PRI: absent
QRS: absent
What is asystole?
The absence of all cardiac electrical activity.
What are the rules of interpretation for Asystole?
Rate: no electrical activity
Rhythm: no electrical activity
Pacemaker site: no electrical activity
P waves: absent
PRI: absent
QRS: absent
What is an Artificial Pacemaker Rhythm?
Results from regular cardiac stimulus by an electrode implanted in the heart and connected to a power source.
In what areas are pacemakers placed?
The right ventricle: ventricular pacemaker
In both the right ventrical and atria: Dual chambered pacemaker
What is the R on T phenomenon?
When PVC's fall within the relative refractory period
What are the rules of interpretation for PVCs?
Rate: depends on underlying rhythm
Rhythm: interrupts regularity of underlying rhythm
pacemaker site: Ventricle
P waves: none; however, interpolated P waves sometimes appear before a PVC
PRI: none
QRS: greater than 0.12 sec and bizarre in morphology.
What is the Lown grading system for premature beats?
Grade 0: No premature beats
Grade 1: <30 per hour
Grade 2: >30 per hour
Grade 3: Multifocal
Grade 4: Repetitive PVC
Grade 5: R on T phenomenon
What is Salvos?
A run of three or four PVC
What is ventricular tachycardia?
VT. Consists of three or more ventricular complexes in succession at a rate od 100 beats per min or more. This rhythm overrides the hearts pacemaker, and the atria and ventricles are asynchronus.
What is monomorphic VT?
The complexes all appear the same
What is polymorphic VT?
The complexes have different sizes and shapes. i.e. Torsades de pointes.
What are the Rules of interpretation for VT?
Rate: 100-250
Rhythm: Usually regular (can be slightly irregular)
Pacemaker site: If present, not associated with the QRS complexes.
PRI: none
QRS: greater than 0.12 sec and bizarre in morphology.
What is Torsades de Pointes?
A polymorphic ventricular tachycardia that differs in appearance and cause from VT in general. Most commonly caused by the use of certain antidysrhythmic drugs. The morphology of the QRS varies from beat to beat.
What is ventricular Fibrillation?
A chaotic ventricular rhythm usually resulting from the presence of many reentry circuits within the ventricles. There is no ventricular depolarization or contractions.
What are the rules of interpretation for VFib?
Rate: no organizes rhythm
Rhythm: no organized rhythm
Pacemaker Site: numerous ectopic foci
P waves: usually absent
PRI: absent
QRS: absent
What is asystole?
The absence of all cardiac electrical activity.
What are the rules of interpretation for Asystole?
Rate: no electrical activity
Rhythm: no electrical activity
Pacemaker site: no electrical activity
P waves: absent
PRI: absent
QRS: absent
What is an Artificial Pacemaker Rhythm?
Results from regular cardiac stimulus by an electrode implanted in the heart and connected to a power source.
In what areas are pacemakers placed?
The right ventricle: ventricular pacemaker
In both the right ventrical and atria: Dual chambered pacemaker