EKG Final

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The heart has three tissue layers. What are they?: 1. Endocardium
2. Myocardium
3. Pericardium
a. Visceral pericardium (epicardium)
b. Parietal pericardium
What are the 4 chambers?: Right atrium, right ventricle, left atrium, left ventricle.
What are the 4 heart valves? Where are they located?: Two semilunar valves:
Pulmonary valve- between the right ventricle and the pulmonary trunk.
Aortic valve- between the left ventricle and the aorta.
Two atrioventricular valves:
Tricuspid valve- between the right atrium and ventricle
Mitral valve- between the left atrium and ventricle.
Rearrange the following list to show how the blood flows through the body beginning with the vena cava: Aorta Pulmonary circulation Vena cava Left ventricle Systemic circulation Right atrium Left atrium Right ventr: Vena cava, right atrium, right ventricle, pulmonary circulation, left atrium, left ventricle, aorta, systemic circulation.
How does the heart receive its nutrients from the blood? Is it during systole or diastole?: Blood drains into the coronary arteries during diastole.
What are the three layers of the wall of an artery?: Tunica intima
Tunica media
Tunica adventitia
Cardiac cycle?: From the end of one contraction to the next.
Diastole?: When the myocardium is relaxed and cardiac filling and coronary perfusion occurs.
Systole?: When the myocardium is contracting.
Ejection fraction? (What is normal?): Ratio of the amount of blood pumped from the ventricles to the amount remaining at the end of diastole.
(2/3 is the normal ejection fraction)
Stroke volume?: The amount of blood ejected by the heart in one contraction.
Cardiac output?: The volume of blood the heart pumps in 1 minute.
Preload?: The pressure within the ventricles at the end of diastole; commonly called the end-diastolic volume.
Afterload?: The resistance against which the heart must pump.
Starling's law of the heart?: The more the myocardium is stretched (up to a certain point) the more forceful the subsequent contraction will be.
Cardiac output = stroke volume x __________: heart rate
cardiac output x systemic vascular resistance = ______________: blood pressure
What 2 components of the autonomic nervous system regulate the heart?: Parasympathetic system, sympathetic system.
Sympathetic system: Neurotransmitter? 2 principal types of receptors?: Norepinephrine, alpha and beta.
Where are the alpha receptors located? What do they cause?: In the peripheral blood vessels.
Vasoconstriction.
There are 2 types of beta receptors- beta 1 and beta 2. Where are they located? What do they cause?: Beta 1 receptors in the heart cause an increase in rate and contractility.
Beta 2 receptors in the lungs cause bronchodilation.
Parasympathetic system: Neurotransmitter?: Acetylcholine.
Chronotropy?: Pertaining to heart rate.
Inotropy?: Pertaining to cardiac contractile force.
Dromotropy?: Pertaining to the speed of impulse transmission.
What are the 3 electrolytes that affect cardiac function?: Na+
K+
Ca++
Intercalated discs?: Specialized bands of tissue inserted between the myocardial cells that increase the rate at which the action potential is spread from cell to cell.
Syncytium?: A group of cardiac muscle cells that physiologically function as a unit.
The heart has 2 syncytia... ______ syncytium ___________ syncytium: Atrial, ventricular.
What is the "all or none" principle?: The only way the impulse can be conducted is through the atrioventricular node.
Resting potential?: The normal resting state of cardiac cells.
Cardiac depolarization?: Quick reversal of the resting potential caused by a rapid influx of Na+ into the cell.
Action potential?: An influx of positive ions into the cell followed by a change in polarity.
Repolarization?: Return of a muscle cell to its preexcitation resting state.
Excitability?: The ability of the cells to respond to an impulse.
Automaticity?: The ability of a cell to spontaneously generate and discharge an impulse.
Conductivity?: The ability of a cell to transmit an impulse.
Contractility?: The ability of the cells to shorten and lengthen muscle fibers.
Pacemaker cells?: Cells that spontaneously depolarize.
Rate of spontaneous depolarization: SA node = AV node = Purkinje system =: 60-100 bpm.
40-60 bpm.
15-40 bpm.
What is an EKG?: An EKG is a graphic representation of the heart's electrical activity.
What is an electrode?: A sensing device that picks up the electrical activity of the heart.
What is a lead?: A view of the heart provided by the electrodes.
What are the 3 types of EKG leads?: 1. Bipolar limb leads.
2. Augmented limb leads (unipolar limb leads).
3. Precordial leads.
A single lead can provide coconsiderable information including...: Rate, regularity, rhythm interpretation.
Lead __ is the most common monitoring lead.: II.
Lead II looks __ at the heart.: Up.
When a wave of depolarization moves toward an electrode the EKG shows a ________ deflection.: Positive.
When a wave of depolarization moves away from an electrode the EKG shows a ________ deflection.: Negative.
Each small box represents ____ seconds. Each large box (made up of 5 small boxes) represents ___ seconds.: 0.04
0.2
What is a normal P wave?: Upright, slightly rounded, smooth.
Why is a P wave upright?: It represents a wave of depolarization moving toward a positive electrode (in lead II).
What is a normal PRI?: 0.12-0.20 seconds (3-5 small boxes)
What is the duration of a normal QRS complex?: <0.12 seconds (<3 boxes)
The Q wave is the first ________ deflection after the P wave. The R wave is the first ________ deflection after the P wave. The S wave is the first ________ deflection after the R wave.: Negative, positive, negative.
What is a normal T wave?: Rounded and upright, usually taller and wider than the P wave.
A normal ST segment is flat on the isoelectric line. An abnormal ST segment can be ________ or _________.: Elevated, depressed.
The refractory period of the heart is divided into 2 portions: ________ refractory period ________ refractory period: Absolute, relative.
Absolute refractory period?: No stimulus can excite the cardiac muscle cells.
Relative refractory period?: Some, but not all of the cells are repolarized. If stimulated, only some will depolarize.
Always use a 5 step process...: 1. Rhythm (regularity)
2. Rate
3. P waves
4. PR intervals
5. QRS complexes
Step 1: Rhythm (2 questions): 1. Are the RR intervals regular?
2. Are the PP intervals regular?
If the rhythm is irregular, ask the following questions...: Is it regular except for 1 or 2 oddball beats?
Is the rhythm regularly irregular or irregularly irregular?
Step 2: Two methods for determining rate...: 1. Boxes method.
2. Six second method.
What is a rate called that is too slow?: Bradycardia.
What is a rate called that is too fast?: Tachycardia.
Bradycardia is a rate less than __ bpm. Tchycardua is a rate greater than ___ bpm.: 60, 100.
Step 3: The P waves. Ask the following questions...: Are there ANY P waves present?
Are the P waves upright?
Do the P waves all look alike?
Is there a P wave in front of every QRS?
Is there a QRS behind every P wave?
Step 4: Check the duration of the PRI. What is normal?: 0.12-0.20 seconds or 3-5 small boxes.
If the PRI is too short (<0.12 seconds), what does that mean?: 1. Pacemaker site is below the SA node- in the atria or in the AV junction.
2. Bypass tract between the atria and the ventricles.
If the PRI is prolonged (>0.20 seconds), what does that mean?: A block in the AV node.
Step 5: Check the duration of the QRS complex. What is normal?: Less than 0.12 seconds (3 boxes).
If the QRS is too wide (>0.12 seconds), what does that mean?: It could be a number of things. For example:
-Ventricular rhythm.
-PVC.
-Drug effects.
-Bundle branch block.
-Hyperkalemia.
Normal sinus rhythm: Rhythm: regular
Rate: 60-100 bpm
P waves: normal in configuration, precede each QRS
PRI: 0.12-0.20 seconds
QRS: <0.12 seconds
Sinus tachycardia: Rhythm: regular
Rate: 100-150 bpm (may be faster)
P waves: normal in configuration, precede each QRS
PRI: 0.12-0.20 seconds
QRS: <0.12 seconds
Sinus tachycardia etiology: Excercise, pain, hypoxemia, shock, some drugs, agitation, caffeine, nicotine.
Sinus bradycardia: Rhythm: regular
Rate: 40-60 bpm (may be slower)
P waves: normal in configuration, precede each QRS.
PRI: 0.12-0.20 seconds
QRS: <0.12 seconds
Is a sinus bradycardia always bad?: No.
Sinus bradycardia etiology: Damage to SA node, increased parasympathetic tone, hypoxemia, normal in conditioned athletes.
Sinus arrhythmia: Rhythm: irregular
Rate: 60-100 bpm (may be slower)
P waves: normal in configuration, precede each QRS
PRI 0.12-0.20 seconds
QRS: <0.12 seconds
Sinus arrhythmia etiology: Respirations (increase in HR with inspiration, decrease in HR with expiration)
Sinus block and sinus arrest etiology: Insult to the SA node, increased parasympathetic tone, hypoxemia.
sinus block: The SA node discharges an impulse that is bloked before it exits the node.
The rhythm resumes in step with the beats preceding the pause.
sinus arrest: The SA node fails to discharge an impulse at all.
The rhythm resumes out of synch with the beats preceding the pause.
How do we recognize sinus P waves?: Upright in lead II, they all look alike, PRI> 0.12 seconds.
Atrial rhythms...: originate in the atria.
wandering atrial pacemaker definition: Pacemaker site shifts between: SA node, other atrial sites, and AV junction. P waves keep changing.
wandering atrial pacemaker interpretation: Rhythm: regular- slightly irregularly irregular
Rate: 60-100 (may be slower)
P waves: vary (should be 3 different mophologies)
PRI: may vary
QRS: <0.12 seconds
wandering atrial pacemaker etiology: May be associated with lung disease, may be normal in the young.
multifocal atrial tachycardia definition: Similar to WAP but rate is >100 bpm.
multifocal atrial tachycardia interpretation: Rhythm: regular-slightly irregularly irregular
Rate: >100
P waves: vary (should be 3 different morphologies)
PRI: may vary
QRS: <0.12 seconds
multifocal atrial tachycardia etiology: Uncommon, not well understood. Associated with heart or lung disease, associated with theophylline use (no longer commonly prescribed).
premature atrial contraction definition: Results from premature discharge of an ectopic atrial focus. Characterized by premature abnormal P wave accompanied by normal QRS followed by a pause.
premature atrial contraction interpretation: Rhythm: underlying is usually regular made irregular because of premature beat
Rate: underlying rate with PAC
P waves: P wave of PAC may be abnormal or even buried in preceding T wave.
PRI: may be normal or <0.12 seconds
QRS: usually <0.12 seconds
premature atrial contraction etiology: Caffeine, tobacco, alcohol, sympathomimetic drugs, ischemic heart disease, hypoxia, digitalis toxicity, ideopathic.
paroxysmal atrial tachycardia definition: Results from rapid discharge of ectopic focus in atria. May be indistinguishable from paroxysmal junctional tachycardia and therefore referred to as paroxysmal supraventricular tachycardia (PSVT).
paroxysmal atrial tachycardia interpretation: Rhythm: regular
Rate: 150-250
P waves: seldom seen because buried in the T waves; if seen, all alike
PRI: may be normal or <0.12 seconds, not always measurable
QRS: usually <0.12 seconds (unless there's aberrant conduction)
paroxysmal atrial tachycardia etiology: Caffeine, nicotine, alcohol, stress, overexertion, sympathomimetic drugs, underlying heart disease.
atrial fibrillation definition: 1. A fib is caused by many irritable atrial foci firing at rapid rate resulting in rapid chaotic atrial rhythm...
2. The atrial impulses bombard the AV node but only some pass through creating a random ventricular pattern- irregularly irregular.
atrial fibrillation interpretation: Rhythm: irregularly irregular
Atrial rate: very fast, chaotic
Ventricular rate: varies
P waves: fibrillatory waves
PRI: not measurable
QRS: <0.12 seconds (unless aberrant conduction
atrial fibrillation etiology: Underlying heart disease, coronary artery disease, hypertension, alcohol.
What are the problems associated with A fib?: 1. Blood pools in the atria causing clots leading to possible stroke.
2. A fib with a rapid ventricular return (uncontrolled rate).
3. Because of the chaotic electrical activity, the atria don't contract leading to reduced cardiac output.
If the atria don't contract, how des the blood get into the ventricles?: Gravity!
atrial flutter definition: Rapid discharge of an ectopic focus in the atria causing atrial rate of 250-500. Only some impulses are conducted through to the ventricles causing slower ventricular rate.
atrial flutter interpretation: Rhythm: regular or irregular
Atrial rate: 250-450
Ventricular rate: varies
P waves: sawtooth flutter waves
PRI: not measurable
QRS: <0.12 seconds
atrial flutter etiology: Underlying heart disease, may result from MI, chronic heart failure.
premature junctional contraction definition: Results from premature discharge of ectopic focus. Characterized by normal QRS and pause.
juncitonal rhythm definition: Originates in the AV junction and takes over when the SA node slows or pauses.
junctional rhythm interpretation: Rhythm: regular
Rate: 40-60
P waves: may be before, after, or buried in the QRS, frequently inverted
PRI: <0.12 or absent
QRS: usually <0.12 seconds
junctional rhythm etiology: Increased vagal tone, pathological slow SA node, heart block.
accelerated junctional rhythm definition: Identical to a junctional rhythm except the rate is 60-100.
accelerated junctional rhythm interpretation: Rhythm: regular
Rate: 60-100
P waves: may be before, after, or buried in the QRS, frequently inverted
PRI: <0.12 or absent
QRS: usually <0.12 seconds
accelerated junctional rhythm etiology: Digitalis effect, after heart surgery or MI, ischemia in the AV junction.
paroxysmal junctional tachycardia definition: Results from rapid discharge of ectopic focus in junction. May be indistinguishable from paroxysmal atrial tachycardia and therefore referred to as paroxysmal supraventricular tachycardia (PSVT).
paroxysmal junctional tachycardia intrpretation: Rhythm: regular
Rate: >100
P waves: inverted; can occur before, after, or buried in QRS
PRI: <0.12 seconds or absent
QRS: usually <0.12 seconds (unless there's aberrant conduction)
paroxysmal junctional tachycarida etiology: Underlying heart disease, ischemia in the AV node, metabolic disturbances.
Ventricular rhythms...: ...originate in the ventricles BELOW the branching portion of the bundle of His.
All ventricular rhythms have a ____ QRS.: Wide.
premature ventricular contraction definition: Results from discharge of an ectopic ventricular focus. Characterized by wide premature distorted QRS with no P wave and followed by a pause.
PVC interpretation: Rhythm: irregular due to premature beat
Rate: varies, can occure in a variety of rhythms
P wave: none with PVC
PRI: none
QRS: wide (>0.12 seconds)
PVC etiology: Myocardial ischemia, increased sympathetic tone, hypoxia, electrolyte disturbances, idiopathic causes, acid base disturbances.
ventricular tachycardia definition: Results from very rapid discharge of ectopic ventricular focus. Usually reflects marked myocardial irritability, may be with a pulse or pulseless.
ventricular tachycardia interpretation: Rhythm: usually regular, may be slightly irregular
Rate: 140-250
P wave: none from ventricles; although usually buried, sinus P waves are sometimes visible
PRI: none
QRS: wide (>0.12 seconds)
ventricular tachycardia etiology: Myocardial ischemia, increased sympathetic tone, hypoxia, acid base disturbances, electrolyte disturbances, ideopathic causes.
ventricular fibrillation defintion: Completely chaotic elctrical activity in the ventricles resulting in a complete lack of ventricular contractions. Always pulseless.
ventricular fibrillation interpretation: Rhythm: chaotic
Rate: none
P wave: none
PRI: none
QRS: none
ventricular fibrillation etiology: MI, hypoxemia, electrolyte disturbances, electrical shock, drugs (digitalis and sympathomimetics).
idioventricular rhythm defintion: A ventricular escape rhythm that results from the failure or blockage of impulses from higher pacemakers.
idioventricular rhythm interpretation: Rhythm: usually regular
Rate: <40
P wave: none
PRI: none
QRS: >0.12 seconds, bizarre
idioventricular rhythm etiology: Slowing of higher pacemakers, high degree AV block, may be first organized rhythm following successful defibrillation.
asystole definition: NO cardiac electrical activity.
asystole interpretation: Rhythm: none
Rate: none
P wave: none
PRI: none
QRS: none
asystole etiology: May be first event in cardiac arrest, failure of conduction system to fire, final EKG in all deaths.
What happens at the AV node in a normal heart? How long is a normal PRI?: The impulse is delayed. the PRI lasts 0.12-0.20 seconds.
There are 4 different AV blocks...: 1. First degree
2. Second degree- Type I
3. Second degree- Type II
4. Third degree
first degree AV block definition: With a first degree block there is a simple delay at the AV node but all impulses are transmitted through.
first degree AV block interpretation: Rhythm: regular
Rate: varies, but atrial and ventricular are the same
P waves: sinus; one P wave to each QRS
PRI: >0.20, remains constant
QRS: usually normal
first degree AV block etiology: Increased vagal tone, MI, drugs (digitalis, amiodorone, beta blockers, calcium channel blockers), idiopathic.
third degree AV block definition: With third degree heart block there is no conduction between the atria and the ventricles. Complete heart block!!
The atria continue to be paced by the SA node at the intrinsic rate of ______ bpm.: 60-100
The venticles are paced by a pacemaker in the AV junction at an intrinsic rate of _____ bpm.: 40-60.
Or by a pacemaker within the ventricles at an intrinsic rate of _____ bpm.: 15-40
third degree AV block interpretation: Rhythm: atrial-regular, ventricular-regular
Rate: atrial and ventricular have different rates
P waves: sinus with no relation to QRS
PRI: varies greatly
QRS: may be <0.12 or wide
third degree AV block etiology: Acute MI, cardiac drugs, ischemic heart disease, insult to AV node.
There are two different second degree blocks...: Second degree type I is also called Mobitz I or sometimes Wenckebach.
Second degree type II is also called Mobitz II.
second degree type I definition: Each successive sinus impulse has increasing difficulty passing throuhg the AV node. Finally one is completely blocked.
second degree AV type I interpretation: Rhythm: atrial-regular, ventricular-irregular
Rate: varies
P waves: sinus; more P waves than QRSs
PRI: become progressively longer until P is nonconducted
QRS: <0.12
second degree AV type I etiology: Increased vagal tone, commonly seen in inferior MI, cardiac drugs, insult to AV node.
second degree type II definition: The SA node transmits a regular serioes of impulses creating P waves. One impulse makes it through the AV node generating a QRS. The next one, up to several, impulses are completely blocked. The EKG strip shows a series of unaccompanied P waves before another impulse finally makes it through the AV node.
second degree AV type II interpretation: Rhythm: atrial-regular, ventricular-irregular
Rate: varies
P waves, sinus; more P waves than QRSs
PRI: normal or prolonged, constant
QRS: <0.12 or wide
second degree AV type II etiology: Hypoxemia, ischemic disease, MI, cardiac drugs, insult to AV node.
We know that all ventricular rhythms have wide QRS complexes. Does that mean that all rhythms that have wide QRS complexes originate in the ventricles?: Nope.
apex: The lower heart border.
point of maximal impulse (PMI): The physical examination landmark that is an indicator of the heart's position within the thorax.
fibrous pericardium: The outer, tough, inelastic, fibrous sac.
serous pericardium: Inner, thin, two-layered, fluid-secreting membrane.
epicardium: The visceral layer.
myocardium: The thick, middle, muscular layer that makes up the bulk of the heart wall.
endocardium: A smooth, thin layer of tissue that lines the heart chambers and valves.
systemic circuit: A large circuit that includes the left side of the heart and vessels, which carry blood to the body and back to the right heart.
pulmonary circuit: A small circuit that include the right side of the heart and vessels, which carry blood to the lungs and back to the left heart.
interatrial septum: The wall dividing the right and left atrium.
interventricular septum: A thicker wall dividing the right and left ventricle.
tricuspid valve: Separating the right atrium from the right ventricle.
pulmonic valve: Separates the right ventricle from the pulmonary arteries.
mitral valve: Separates the left atrium from the left ventricle.
aortic valve: separates the left ventricle from the aorta.
atrioventricular valves: The tricuspid and mitral valves.
chordae tendinae: "Heart strings."
semilunar valves: The aortic and pulmonic valves.
collateral vessels (collateral circulation): Small arteries that provide the potential for cross flow from one artery to the other.
myocardial cells: Working or mechanical cells.
actin and myosin: Contractile protein filaments.
electrolyte: A substance whose molecules dissociate into charged particles (ions) when placed in water, producing positively and negatively charged ions.
cation: An ion with a positive charge.
anion: An ion with a negative charge.
membrane channels (pores): Openings through which ions pass back and forth between the extracellular and intacellular spaces.
concentration gradient: Particles in solution move, or diffuse, from areas of higher concentration to areas of lower concentration.
electrical gradient: Charged particles also diffuse, but the diffusion of charged particles is influenced not only by the concentration gradient but also by an electrical gradient.
sodium-potassium pump: A mechanism that actively transports ions across the cell membrane against its electrochemical gradient.
right bundle branch: Conducts the electrical impulse to the right ventricle.
left bundle branch: Divides into two divisions: the anterior fascicle and the posterior fascicle.
anterior fascicle: Carries the electrical impulse to the anterior wall of the left ventricle.
posterior fascicle: Carries the electrical impulse to the posterior wall of the left ventricle.
Purkinje fibers: Conduction fibers.
His-Purkinje system: Refers to the bundle of His, bundle branches, and the Purkinje fibers.
P wave: Depicts atrial depolarization, or the spread of the impulse from the SA node throughout the atria.
PR interval: Represents the time from the onset of atrial depolarization to the onset of ventricular depolarization.
PR segment: The short isoelectric line between the end of the P wave to the beginning of the QRS complex.
QRS complex: Depicts ventricular depolarization, or the spread of the impulse throughout the venricles.
ST segment: Represents the end of ventricular depolarization and the beginning of ventricular repolarization.
T wave: Represents the latter phase of ventricular repolarization.
U wave: Thought to represent further repolarization of the ventricles.
QT interval: Represents both ventricular depolarization and repolarization
R-R interval: From one R wave to the next R wave.
biphasic deflection: A deflection haveing both a positive and negative component.
supernormal period: During this period the cardiac cells will respond to a weaker than normal stimulus.
p pulmonale: The abnormal P wave in right atrial enlargement.
p mitrate: The abnormal P waves seen in left atrial enlargement.
Wolff-Parkinson-White (WPW) syndrome: An example of a bypass channel.
J point: The point where the QRS complex ends.
QS complex: If the entire complex is negative.
R prime: The second R wave.
S prime: The second S wave.
notch: A wave that changes direction but doesn't cross baseline.
five-leadwire system: Five electrode pads and five leadwires are used.
three-leadwire system: Three electrode pads and three leadwires are used.
arrhythmia (dysrhythmia): Refers to all rhythms other than the normal sinus rhythm of the heart.
tachy-brady syndrome: Sick sinus syndrome.
sinus pause: A broad term used to describe rhythms in which there is a sudden failure of the SA node to initiate or conduct an impulse.
ectopic: Rhythms that originate from any site other than the SA node.
ectopic pacemaker: A pacemaker other than the sinus node.
altered automaticity: The automaticity of the sinus node does not exceed that of all other parts of the conduction system.
triggered activity (after-depolarization): An abnormal condition in which myocardial cells may depolarize more than once after stimulation by a single electrical impulse.
reentry: An impulse travels through an area of myocardium, depolarizes it, and then reenter that same area to depolarize it again.
aberrantly conducted PACs: PACs associated with a wide QRS complex.
bigeminal PACs: Every other beat.
trigeminal PACs: Every third beat.
Quadrigeminal PACs: Every fourth beat.
couplets: Couplets.
atrial escape beats: Ectopic atrial beats that occur late instead of early.
T-P wave: The T wave and P wave appear as one deflection.
flutter waves: Sawtooth deflections.
fibrillatory waves: Irregular, wavy deflections.
coarse fibrillatory waves: Large fibrillatory waves.
fine fibrillatory waves: Small fibrillatory waves.
fib-flutter: Flutter waves mixed with fibrillatory waves.
controlled atrial fibrillation: When the ventricular rate is less than 100 bpm.
uncontrolled atrial fibrillation (atrial fibrillation with a rapid ventricular response): When the ventricular rate is greater than 100 bpm.
junctional escape beats: Ectopic junctional beats that occur late instead of early.
supraventricular: Any rhythm above the bifurcation of the bundle of His.
heart block: Arrhythmias in which there is delayed or failed conduction of supraventricular impulses through the AV node into the venricles.
Stokes-Adams attacks (Stokes-Adams syncope): Fainting spells associated with complete heart block.
sequential depolarization: Depolarization of one ventricle before the other.
uniform or unifocal PVCs: PVCs that are identical in size, shape, and direction.
multiform or multifocal PVCs: PVCs from different ectopic sites.
interpolated PVC: A PVC sandwiched between two normally conducted sinus beats, without greatly disturbing the regularity of the underlying rhythm.
R-on-T phenomenon: A PVC that has occurred during the vulnerable period of repolarization.
ventricular escape beats: Ventricular beats that occur late instead of early.
ventricular flutter: VT occurring at rates greater than 250 bpm.
torsades de pointes: "Twisting of the points."
coarse ventricular fibrillation: When fibrillatory waves are large.
fine ventricular fibrillation: When fibrillatory waves are small.
sensing: The pulse generator is able to "see" intrinsic patient beats.
firing: The pulse generator has delivered a stimulus to the heart.

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