Download Cardiac Dysrhythmias Exam: Junctional and Ventricular Arrhythmias with Solutions and more Exams Nursing in PDF only on Docsity!
NSCC-7150 Final Set Exam With
Complete Solutions
what is a junctional dysrhythmia? - ANSWER rhythms that originate in the AV junction
Why do junctional dysrhythmias occur? - ANSWER Junctional dysrhythmias occur because the SA node fails to fire or the impulse from the SA node is blocked at the AV node- so a secondary pacemaker site in AV junction take over
what are the 4 types of junctional dysrhythmias? - ANSWER 1- premature junctional contractions
2- junctional escape rhythm
3- junctional tachycardia
4- supraventricular tachycardia
where does the site of impulse formation occur for premature junctional contractions? - ANSWER junctional tissue
how does a PJC occur? - ANSWER PJC occurs when an impulse-forming cell fires 'earlier'/prematurely than the regular interval for impulses
is there atrial depolarization in PJCs? - ANSWER Yes- the impulses that originate in the junctional tissue will still result in atrial depolarization- however the P waves (if visible) will look different from each other
atrial tissue is depolarized in a retrograde manner (reverse)
3 ways the P wave may appear in a PJC - ANSWER 1- inverted
2- buried in the QRS complex thus not visible
3- after the QRS complex
in all these cases, depolarization starts at the AV junction and proceeds from there
T/F PJC can occur as a single isolated beat, or in cluster of groups of beats - ANSWER TRUE
describe the conduction problem in PJCs - ANSWER pacemaker site can be the SA node with the occasional or cluster of beats from back up pacemaker in the AV junction- these back up beats happen prematurely
possible causes of PJCs - ANSWER alcohol, tobacco, other stimulants, cardiac disease
or dig toxicity
implications for O2 supply & demand in PJCs - ANSWER depends on frequency of PJC which can affect overall HR, loss of atrial kick with each PJC which affects preload and overall decrease in CO
interventions for PJCs - ANSWER assess pt, are the premature beats causing symptoms? pharmacologic interventions to speed up SA node firing may be prescribed.
beta adrenergic antagonists (beta blockers) or calcium channel antagonists (calcium channel blockers) may be used if pt symptomatic
tx underlying cause
rate and rhythm of PJCs - ANSWER -rate may be normal depending on number of PJCs occurring
-rhythm underlying regular but may appear irregular with premature beats
what is a junctional escape rhythm? why does this occur? - ANSWER in JER, the secondary pacemaker site in the junctional tissue takes over the role of impulse formation
usually occurs when the primary pacemaker site in the SA node fails
what is there inherent firing rate of junctional pacemaker sites? - ANSWER 40-
Regular rate of a JER vs accelerated junction rhythm - ANSWER regular: 40-60 bpm
accelerate: 60-100 bpm
electrical conduction of JER - ANSWER impulse initiated in the junctional tissue, atrial tissue depolarized in retrograde manner, ventricular depolarization occurs in 'normal' manner so the QRS complexes will appear normal
3 ways the P wave may appear in a JER - ANSWER same as PJC
-inverted
-buried in the QRS complex thus not visible
-after the QRS complex
A JER with rate of 60-100 bpm is called what? - ANSWER accelerated JER
conduction problem of JERs - ANSWER -source of impulse of the junction, conduction occurs normally thru AV and ventricle conduction system
-concern with this rhythm is whether the rate is sufficient to meet pt needs
-assess pt and response to rhythm
interventions for junctional tachy - ANSWER assess pt, if cause is readily apparent treat the cause, if cause not easily defined treat symptoms
(amiodarone)
rate and rhythm of junctional tachy - ANSWER rate is greater than 100 hence the tachy
rhythm is regular
What is SVT (Supraventricular Tachycardia)? - ANSWER supra/ventricular - above ventricles
tachy- fast (> 100 bpm)
So- SVT are dysrhythmias with a fast rate whose site of impulse formation is above the ventricles
4 types of SVT - ANSWER atrial fib
atrial flutter
atrial tachy
junctional tachy
what do you call a SVT that starts suddenly or ends suddenly? - ANSWER paroxysmal SVT
T/F when going thru the steps of determining a rhythm, the term SVT is given to a rhythm where we cannot differentiate between a fib, a flutter, atrial tachy or junctional tachy - but the only thing you can be certain of is that the rhythm originates from some point above the ventricles - ANSWER TRUE
SVT Implications for O2 supply & demand - ANSWER HR of 150 bpm may result in significant hemodynamic compromise for some pts, increases myocardial oxygen supply demand in all pts
SVT interventions - ANSWER -vagal maneuvers such as coughing, bearing down, carotid sinus massage) may be used to slow down SVT
-drugs such as adenosine
characteristics of ventricular dysrhythmias (2) - ANSWER -rhythms that originate in the ventricles
-can be fast or slow
when do fast ventricular dysrhythmias occur? - ANSWER occur when an irritable focus or multiple foci take over from pacemaker sites higher up in the conduction system (ie: override the SA node or the junctional tissue)
when do slow ventricular rhythms occur? - ANSWER occur when the SA node or AV junction pace maker sites fail or are completely blocked ,and a pacemaker site in the conduction system below the AV junction takes over pacemaker role
5 types of ventricular dysrhythmias - ANSWER 1- premature ventricular contractions (PVCs)
2- ventricular tachycardia (V tach)
3- ventricular fibrillation (V fib)
4- ventricular escape or idioventricular rhythm
5- accelerated idioventricular rhythm
What is a premature ventricular contraction - ANSWER arises from an irritable focus within the ventricles that fires prematurely to initiate an ectopic or abnormal beat
define uni-focal and multi-focal PVCs - ANSWER uni-focal - PVCs that arise from the same abnormal focus
multi-focal- PVCs that arise from more than one abnormal foci
which is worse multi-focal or uni-focal PVC? - ANSWER multifocal are considered to be more threatening as they indicate widespread irritability in the ventricles
describe the appearance of the QRS in a PVC? - ANSWER wide and bizarre looking- because the impulse originates in the ventricles and does not travel thru the normal conduction system, as a result depolarization takes longer so it is wider, bizarre and often slurred or notched
define ventricular bigeminy, trigeminy, & quadrigeminy - ANSWER BI-geminy: every 2nd beat is a PVC
TRI-geminy: every 3rd beat is a PVC
QUAD-rigeminy: every 4th beat is a PVC
define the PVC terms: couplet, triplet and run - ANSWER COUP-let: 2 PVCs occurring together
what happens to the atria in v tach? where is the P wave? - ANSWER atrial usually continue to be depolarized independently- dissociated form the ventricular activity
P wave typically not visible and are buried in bizarre, wide QRS complexes
why is the QRS complex wide and bizarre in V tach? - ANSWER same as in PVCs, appear abnormal but impulses originate from the ventricles, and takes longer to depolarize which makes them wide
site of impulse formation in v tach - ANSWER ventricular tissue
possible causes of v tach? - ANSWER heart disease (esp ischemic ad valvular disease), dig tox, hypoxemia, electrolyte imbalances, acid base disturbances
implications to O2 supply & demand in v tach - ANSWER -increased HR increases myocardial oxygen demand/consumption which can lead to further ischemia and tissue damage
-loss of atrial kick as v rate is over the SA node rate and loss of synchronization between atria and ventricles
-rapid HR shortens diastolic filling time, ventricles do not get enough time to fill - decrease in SV and CO
-coronary artery perfusion impaired d/t shortened diastolic filling time, impacts contractility and CO
what determines the interventions for V tach - ANSWER if the pt has a pulse or not
intervention for pt in v tach with & without a pulse - ANSWER with: cardioversion
without: defibrillation
rate and rhythm of v tach - ANSWER rate usually between 100-250bpm but can be higher
rhythm is regular
which ACLS algorithm do you follow if your pt is experiencing v tach with a pulse? - ANSWER tachycardia algorithm
which ACLS algorithm do you follow if your pt is experiencing v tach without a pulse - ANSWER cardiac arrest algorithm
in a pt experiencing v tach with a pulse, what is the next step to determine? - ANSWER are they stable or unstable? (ie: SOB, hypotensive, CP, decreased LOC)term-
what do you do if your v tach pt with a pulse is stable? - ANSWER ALCS recommends using drugs to convert or slow down the dysrhythmia. Drug of choice based on whether the QRS complex is wide or narrow
what do you do if your v tach pt with a pulse is unstable? - ANSWER ACLS recommends synchronized cardioversion
how would you describe ventricular fibrillation - ANSWER bad news, hearts electrical activity is chaotic, irregular and disorganized
T/F in v fib, the pt has a pulse - ANSWER FALSE- the ventricles quiver rather than contract in an organized manner, therefore no effective CO, and NO pulse
T/F v fib is not compatible with life. - ANSWER TRUE
how would you describe the morphology of v fib rhythm? - ANSWER no discernable complexes or waveforms in the ECG strip showing v fib
site of impulse formation in v fib - ANSWER ventricular tissue
causes of v fib - ANSWER myocardial ischemia is the main cause
implications to O2 supply and demand in ventricular escape rhythms - ANSWER slow ventricular rate and loss of atrial kick will result in decrease CO
interventions for ventricular escape rhythms - ANSWER -assess pt, are they symptomatic? tx symptoms
-atropine to increase rate
-external pacemaker may be warranted and is recommended
is there a P wave in VER? - ANSWER no, impulse from ventricular tissue hence no P wave, thus no PR interval measurable
loss of atrial kick
what is an accelerated idioventricular rhythm? - ANSWER it is a ventricular escape rhythm aka idioventricular rhythm but the rate is accelerated at 40-100bpm
when does accelerated idioventricular or VER occur most frequently? - ANSWER post-thrombolytic therapy
name as many of the reversible causes in the ACLS cardiac arrest algorithm as you can
- ANSWER hypovolemia, hypoxia, acidosis, hypo/hyperkalemia, tension pneumothorax, hypothermia, toxins, cardiac tamponade, pulmonary/coronary thrombosis
what assessments determine if ROSC has been achieved? - ANSWER -return of pulse, BP
-abrupt sustained increase in PETCO2 typically greater than or = to 40mmhg
-spontaneous arterial pressure waves in intra-arterial monitoring
6 characteristics of quality CPR - ANSWER -push hard least 2 inches (5cm) deep
-push fast at 100-120 bpm
-minimize interruptions in compressions
-switch compressor every 2 mins or more frequent if fatigued
-avoid excessive ventilation
-if no advanced airway, 30:2 compression ventilation ratio
how to administer adenosine IV in the adult tachy w/ pulse ACLS algorithm - ANSWER -adenosine rapid IV push - given FAST
-initial dose 6mg rapid IV push followed with NS flush
-second dose if required 12mg
what 2 considerations are there to make in synchronized cardioversion in the ACLS adult tachy algorithm? - ANSWER -sedation
-if reg narrow complex consider adenosine
first step of the ACLS adult tachy algorithm - ANSWER assess appropriateness for clinical condition- typically HR of greater than or equal to 150 bpm if tachyarrhythmia
what are AV blocks? - ANSWER atrioventricular blocks are a group of dysrhythmias that are characterized by a delay or blockage of impulse within the conduction system
3 things AV blocks clinical significance depend on - ANSWER 1- the degree or severity of the block
2- rate of the secondary pacemaker
3- pts response to the AV block
name the 4 types of AV block rhythms: - ANSWER 1- first degree AV block
2- second degree AV block TYPE 1 (AKA Wenckebach)
3- second degree AV block TYPE 2
4- third degree AV block
rate and rhythm of first degree AV block - ANSWER rate 60-100bpm
rhythm regular
what is second degree type 1 AV block also known as - ANSWER Wenckebach
describe the impulse pathway of second degree AV block type 1 - ANSWER SA node initiates impulses, however each impulse is delayed in the AV node a little longer than the preceding one, until one is finally completely blocked. the impulses that are conducted thru the AV node are conducted normally thru the ventricles
describe the morphology of second degree AV block type 1 - ANSWER P wave, QRS complex, T wave appear normal because impulses follow normal conduction system, but the PR interval will become progressively longer until a QRS is missed or dropped
classic pattern of PR intervals in second degree AV block type 1 - ANSWER longer longer, dropped; longer, longer, dropped.
conduction problem of second degree AV block type 1 - ANSWER impulses take progressively longer to conduct thru AV node (progressively longer PR interval) - eventually P waves falls during the refractory period of the ventricles and therefore will not be conducted thru resulting in a QRS is missed/dropped
cause of second degree AV block type 1 - ANSWER ischemia of the AV node secondary to right coronary artery occlusion
also drugs such as beta blockers, digoxin, and inferior MIs
implications to O2 supply & demand in second degree AV block type 1 - ANSWER effects on CO are directly related to how slow the underlying rhythm is and the number of dropped QRS complexes, and there is potential for this block to progress into more severe block like third degree av block
interventions for second degree AV block type 1 - ANSWER assess pt, usually asymptomatic, if HR (ventricular) is below 60, and pt has symptoms, atropine or
temporary pacing may be considered
rate and rhythm of second degree AV block type 1 - ANSWER rate: 60-100 bpm (may be slower) atrial rate greater than ventricular rate
rhythm: irregular
describe the impulse pathway in second degree AV block type 2 - ANSWER some impulses are blocked from travelling from the SA node into the lower conduction system , while other impulses are conducted
describe the morphology of second degree AV block type 2 - ANSWER -PR interval will be the same length for all complexes (fixed PR interval, often prolonged)
-P waves appear normal, but there are more P waves than QRS complexes
-QRS complex appear normal
describe the significance of the P : QRS ratio in second degree AV block type 2 - ANSWER can vary within one ECG strip, but the P : QRS ratio indicates the number of impulses that are being blocked
Is type 1 or type 2 second degree AV block more serious? - ANSWER type 2- as it frequently progresses to the worst type of av block (3rd degree) and cardiac output may be severely compromised from the infrequent QRS complexes which represent ventricular contraction and generate CO
what does the P : QRS ratio represent in second degree AV block type 2 - ANSWER the ratio of impulses arriving at the AV junction to impulses that are conducted thru the ventricles
when interpreting second degree AV block type 2, what is key to analyze and state? - ANSWER key to analyze is the ratio of impulses arriving at the AV junction to impulses that are conducted thru the ventricles , and when interpreting to state the ratio (ie: second degree AV block type 2 with a 2:1 block)
how are the atria depolarized in third degree av block - ANSWER the SA node continues to fire even tho the impulses are not being conducted which creates atrial depolarization as usual - normal looking P wave
T/F because of the complete AV block, there is no relationship between atria and ventricle activity - ANSWER TRUE
what is the term for when the atrial pacemaker (SA node) and the ventricular pacemakers operate completely independently in third degree av block - ANSWER AV dissociation - because the atrial and ventricular chambers are, electrically speaking, dissociated from each other
what happens to rate and rhythm of the atria and ventricles in third degree av block? - ANSWER atrial and ventricular rates will be different but each rhythm will have its own regular rate
describe the morphology of third degree av block - ANSWER - p wave normal
-no true PR interval
-absolutely no relationship between P wave and QRS complexes
-QRS complexes will vary depending on level of secondary or escape pacemaker (narrow or wide and bizarre)
where does the complete block occur in third degree av block? - ANSWER can occur anywhere from the AV junction --> down (ie: AV node, bundle of HIS, bundle branches)
narrow QRS complex in third degree av block means... - ANSWER impulse is originating from an escape rhythm just below the junction therefore narrow QRS complex
wide and bizarre QRS complex in third degree av block means... - ANSWER impulse is originating from an escape rhythm from the ventricles therefore a wide QRS complex
T/F in third degree av block, the father the pacemaker site is from the AV node, the wider the QRS complexes will be - ANSWER TRUE
explain the conduction problem in third degree av block - ANSWER impulses generated by the SA node are completely blocked and not conducted thru to ventricles, so a secondary or escape pacemaker site stimulates the ventricles
cause of third degree av block - ANSWER ischemia or MI
implications to O2 supply & demand in third degree av block - ANSWER effect on CO is based on:
-how slow the V rate is (slower the V rate, lower the CO)
-loss of atrial kick, SA node completely blocked so no atrial kick is present to assist with ventricular filling, decrease up to 30% CO
interventions for third degree av block - ANSWER check, assess pt. Atropine is symptomatic, but likely temporary pacing will be initiated
rate and rhythm of third degree av block - ANSWER rate: atrial rate greater than ventricular rate
rhythm: atrial rate and ventricular rate are regular in their own way. NO relationship between atria and ventricles
briefly state how to recognize each AV block: - ANSWER -First degree: look for constant prolonged PR intervals (>0.20s)
-Second degree T1: look for progressively longer PR intervals until a QRS complex is dropped/missed (Wenckebach pattern)
-Second degree T2: look for fixed prolonged PR, with more Ps than QRS complexes, state the ratio and underlying rhythm
-Third degree: Av dissociation- atria and ventricles at regular rates but no relationship, the farther the pacemaker is from the AV node, the wider the complexes are
and oxygen supply
which dysrhythmias require cardiac pacing? - ANSWER sinus brady or sinus arrest
all the AV blocks
sick sinus syndrome
tachy-dysrhythmias
what are the 2 other non-dysrhythmic indications for pacing - ANSWER -myocardial ischemia or infarction (that results in AV blocks or bradycardia)
-post cardiac sx, as the surgical process or associated edema can disrupt conduction
what is the pulse generator of a cardiac pacemaker and what does it do? - ANSWER it is the power source
generates an electrical current that is transmitted to the heart, and also has circuitry capable of sensing the hearts intrinsic rhythm
how is the pulse generators electrical impulse transmitted? - ANSWER via the pacing lead(s)
T/F settings of a cardiac pacemaker can be tailored to meet an individual pts needs - ANSWER TRUE
Which basic settings (3 dials) are required for temporary, single chamber pacing? - ANSWER 1) desired HR- set to level that will support adequate CO for the pt (30-180)
strength of electrical impulse- delivered to cardiac tissue in order to initiate depolarization (0.1-20)
sensitivity of the pacemaker system to the pts intrinsic electrical activity (20-.5)
How is strength of electrical impulse expressed in pacemaker settings? - ANSWER output, or mA
how is appropriate mA for a pt determined? (3 steps) - ANSWER -by increasing the mA dial while watching the pts ECG looking for evidence of paced beats
-once paced beat noted, output level is noted and referred to as the pacing threshold
-mA usually set to approx. 2-3 times the pacing threshold
defined 'sensitivity' in pacemaker settings - ANSWER the 'size' of electrical activity that needs to be generated during a pts intrinsic depolarization in order for the pacemaker to sense it.
How is sensitivity set in pacemaker settings? - ANSWER -set in millivolts (mV)
-higher the mV, the larger the amount of electrical activity the heart has to generate in order for the pacemaker to recognize it
low vs high mV settings - ANSWER low mV setting means that the pacemaker is more sensitive to pt electrical activity
high mV setting means that the pacemaker is less sensitive to pts electrical activity
why is the sensitivity setting important? - ANSWER it allows the pacemaker to work in concert with the pts own electrical activity
IE: when the pacemaker senses the pts intrinsic activity, it will respond in a pre-programmed manner, usually by inhibiting itself from firing so it prevents it from firing on the pts T wave, etc.
how is the sensitivity setting determined? - ANSWER determine the level of mV at which the pacemaker can sense pts activity (sensing threshold) and then set the sensitivity to 1/2 of that level
(IE: if the sensing threshold was 4mV, set sensitivity to 2mV)
