T5: Dysrhythmias, Defib, Pacemakers Flashcards
parasympathetic nervous system ____ the rate of the SA node
decreases
sympathetic nervous system ____ the rate of the SA node
increases
SA node is the
pacemaker of the heart
bpm of SA node
60-100 beat/minutes
what are the secondary pacemakers
AV node and Purkinje fibers
bpm of av node
40-60 bpm
bpm of purkinje fibers
20-40 bpm
placing 12-lead ECG
-Clip excessive hair on chest wall
-Rub skin with dry gauze
-May need to use alcohol for oily skin
-Apply electrode pad
-Artifact-movement or poor lead contact
when a client presents with a dysrhythmia what should the nurse do
assess the clinical status of the patient, do not treat the monitor
normal sinus rhythm (NSR)
*refers to a rhythm that starts in the SA node at a rate of 60 to 100 times per minute and follows the normal conduction pathway.
sinus tachycardia
*normal sinus rhythm. The sinus rate is 101 to 200 beats/minute
sinus tachycardia is associated with
*physiologic and psychologic stressors
treatment for sinus tachycardia
*Guided by cause (e.g., treat pain)
*Vagal maneuver
*β-blockers (metoprolol)
sinus bradycardia
*the conduction pathway is the same as that in sinus rhythm but the SA node fires at a rate less than 60 beats/minute
Sinus bradycardia may be a normal sinus rhythm in
*aerobically trained athletes and in some people during sleep.
clinical manifestations of sinus bradycardia
*Hypotension
*Pale, cool skin
*Weakness
*Angina
*Dizziness or syncope
*Confusion or disorientation
*Shortness of breath
treatment for sinus bradycardia
Unstable: atropine
stable: pacemaker
*Stop offending drugs
atrial fibrillation
*characterized by a total disorganization of atrial electrical activity due to multiple ectopic foci resulting in loss of effective atrial contraction.
*rate may be as high as 350 to 600 beats/minute.
in a fib the P wave is replaced by
*chaotic, fibrillatory waves.
a fib caused a
decrease in CO and an increased risk for stroke and clots
treatment for a-fib
*Drugs to control ventricular rate and/or convert to sinus rhythm (amiodarone and ibutilide most common)
*Electrical cardioversion
*Anticoagulation
*Radiofrequency ablation
*Maze procedure with cryoablation
Paroxysmal Supraventricular Tachycardia (PSVT)
A dysrhythmia originating in an ectopic focus anywhere above the bifurcation of the bundle of His. P wave is often hidden in preceding T wave, but if seen may have an abnormal shape. The PR interval may be shortened or normal, and QRS is usually normal.
BPM for PSVT
150 to 220 beats/minute
PSVT is associated with
*overexertion, stress, deep inspiration, stimulants, disease, digitalis toxicity, hormones, anesthesia
clinical manifestations of PSVT
*HR is 150-220 beats/minute (add for clarification)
*HR > 180 leads to decreased cardiac output and stroke volume
*Hypotension
*Dyspnea
*Angina
what medication should be given if the patient is symptomatic with PSVT
IV adenosine
treatment for PSVT
*Vagal stimulation
*IV adenosine
*IV β-blockers
*Calcium channel blockers
*Amiodarone
*DC cardioversion
Adenosine half life
10 seconds
first degree heart block
*a type of AV block in which every impulse is conducted to the ventricles but the time of AV conduction is prolonged. After the impulse moves through the AV node, the ventricles usually respond normally.
clinical manifestations first degree heart block
*Typically not serious
*Patients asymptomatic
treatment for first degree heart block
*No treatment
*Monitor for changes in heart rhythm
third degree heart block
complete heart block, Atrial and ventricular rhythms are regular but unrelated to each other.
Third-degree AV block usually results in
reduced CO with subsequent ischemia, HF, and shock.
treatment for symptomatic patietns with third degree heart block
*a transcutaneous pacemaker is used until a temporary transvenous pacemaker can be inserted.
what drugs are used as a temporary measure to increase HR and support blood pressure until temporary pacing is started in third degree heart block
dopamine (Intropin), and epinephrine
A run of three or more PVCs defines
ventricular tachycardia
ventricular tachycardia
occurs when an ectopic focus or foci fire repeatedly and the ventricle takes control as the pacemaker rate 150-250bpm
Monomorphic VT has QRS complexes that are
*the same in shape, size, and direction.
Polymorphic VT occurs when
*the QRS complexes gradually change back and forth from one shape, size, and direction to another over a series of beats.
why is v-tach considered life threatening
*because of decreased CO and the possibility of deterioration to ventricular fibrillation
treatment for stable v-tach (with pulse)
*treated with antidysrhythmics or cardioversion if more unstable
treatment for unstable v-tach (no pulse)
*treated with CPR and rapid defibrillation
ventricular fibrillation
*a severe derangement of the heart rhythm characterized on ECG by irregular waveforms of varying shapes and amplitude.
ventricular fibrillation results in an
*unresponsive, pulseless, and apneic state.
treatment for ventricular fibrillation
*immediate CPR and ACLS
*Defibrillation
*Drug therapy (epinephrine, vasopressin)
torsades de pointes
*polymorphic VT associated with a prolonged QT interval of the underlying rhythm.
treatment for torsades de pointes
Treatment same as VT but ALSO include Magnesium as treatment-reduces irritability
Pulseless Electrical Activity (PEA)
*a situation in which organized, electrical activity is seen on the ECG, but there is no mechanical heart activity and the patient has no pulse.
common causes of PEA
Hs and Ts
*Hypovolemia
*Hypoxia
*Hydrogen ion (acidosis)
*Hyper-/hypokalemia
*Hypoglycemia
*Hypothermia
*Toxins
*Tamponade (cardiac)
*Thrombosis (MI and pulmonary)
*Tension pneumothorax
*Trauma
treatment of PEA
CPR followed by intubation and IV epinephrine
Treatment is directed toward correction of the underlying cause
asystole
*Represents total absence of ventricular electrical activity
*No ventricular contraction
clinical manifestations of asystole
*Patient unresponsive, pulseless, apneic
treatment of asystole
*immediate CPR and ACLS measures
*Epinephrine and/or vasopressin
*Intubation
Sudden Cardiac Death (SCD)
unexpected death from cardiac causes
Defibrillation
*the treatment of choice to end VF and pulseless VT.
defibrillation is most effective when
*completed within 2 minutes of dysrhythmia onset
general steps for defibrillation:
1.Start CPR while obtaining and setting up defibrillator
2.Turn on and select energy
3.Make sure sync button is turned off
4.Apply gel pads
5.Charge
6.Position paddles firmly on chest
7.Ensure “All clear”!!!!!
8.Deliver charge
Synchronized Cardioversion
*Choice of therapy for ventricular ( VT with a pulse) or supraventricular tachydysrhythmias
*Synchronized circuit delivers a countershock on the R wave of the QRS complex of the ECG
Implantable Cardioverter-Defibrillator (ICD)
*Consists of a lead system placed via subclavian vein to the endocardium
*Battery-powered pulse generator is implanted subcutaneously
*Sensing system monitors HR and rhythm - delivering 25 joules or less to heart when detects lethal dysrhythmia
Implantable Cardioverter-Defibrillator (ICD) Patient and Caregiver Teaching
1.Follow-up appointments
2.Incision care
3.ARM RESTRICTIONS
4.Sexual activity
5.Driving
6.Avoid direct blows
7.Avoid large magnets, MRI
8.Air travel not restricted
9.Avoid antitheft devices
10.What to do if ICD fires
11.Medic Alert ID
12.ICD identification card
13.Caregivers to learn CPR
Implantable Cardioverter-Defibrillator (ICD) *Variety of emotions are possible:
*Fear of body image change, recurrent dysrhythmia, pain with ICD discharge , Anxiety about going home
*Participation in an ICD support group should be encouraged
pacemakers
*Used to pace the heart when the normal conduction pathway is damaged
pacemaker: fixed mode
SET Consistent rate always
pacemaker: demand mode
firing only when HR drops below preset rate
Antitachycardia pacing:
*delivery of a stimulus to the ventricle to terminate tachydysrhythmias
*Overdrive pacing:
*pacing the atrium at rates of 200-500 impulses/minute to terminate atrial tachycardias
Pacemaker Spike
precedes each pacemaker-induced QRS complex– narrow, biphasic deflection.
Temporary Pacemakers
*Power source outside the body
Temporary Pacemakers: transvenous
*Transvenous-through Central line
Temporary Pacemakers: epicardial
through chest wall post surgery
Temporary Pacemakers: trancutaneous
through skin in emergency
Epicardial pacing involves
*attaching an atrial and ventricular pacing lead to the epicardium during heart surgery.
use transcutaneous pacing at
*lowest current that will “capture”
Failure to sense occurs when
when the pacemaker fails to recognize spontaneous atrial or ventricular activity, and it fires inappropriately
*This can result in the pacemaker firing during the excitable period of the cardiac cycle resulting in VT.
Failure to capture occurs when
*the electrical charge to the myocardium is insufficient to produce atrial or ventricular contraction. This can result in serious bradycardia or asystole.
pacemaker post procedure
*Limit arm and shoulder activity
-no driving, may put arm in sling
*Monitor insertion site for bleeding and infection
*Patient teaching important
