Dysrhythmias Identification and Pharmacologic Treatment - Exam 6 Flashcards
Which comes first: mechanical activity of the heart or electrical activity of the heart?
Electrical activity comes first.
What is automaticity?
The unique ability of the cardiac muscle cells to generate and conduct electrical activity
What is the main pacemaker of the heart?
The SA node
What is the rate of discharge of the SA node?
60-100 bpm
What is the SA node’s backup?
The AV node
What is the rate of discharge of the AV node?
If the SA node fails to fire:
40-60 bpm
What is the back up if both of the natural pacemakers of the heart fail to discharge?
Purkinje fibers
What is the rate of discharge of the perkinje fibers?
20-40 bpm
Depolarization of what takes place during the P-wave?
atrial depolarization
Depolarization of what takes place during QRS?
ventricular depolarization
What is dysrhythmia?
The absence of a rhythmic pattern. A term also commonly used to refer to any deviation from the normal pattern of the heartbeat, or dysrhythmia. May also be called arrhythmia.
What is ectopic focus?
Any cell other than the sinus node which is initiating impulses and causing myocardial depolarization
What is excitability?
Ability of cardiac cells to be electrically stimulated
What is refractory period?
Repolarization of the cardiac muscle of which the cardiac muscle is resistant to stimulation. This refractory period consists of two stages: the absolute and relative refractory period. If a stimulus is strong enough during the relative refractory period, it can cause depolarization that could lead to a lethal cardiac rhythm.
What are common causes of dysrhythmias?
- Hypovolemia
- Hypoxia
- Hydrogen ion (acidosis)
- Hypo-Hyperkalemia (Ca, Mg)
- Hypoglycemia
- Hypothermia
- Toxins (caffeine, cocaine, drugs)
- Tamponade (cardiac)
- Tension pneumothorax
- Thrombus (coronary, pulmonary)
- Trauma (hypovolemia, SNS, increase ICP)
- Thyroid disorder
In the name of a rhythm, what does the first part refer to?
The first part tells the location of the impulse
“sinus bradycardia”
sinus = impulse originates from SA node
What is normal sinus rhythm?
Sinus rhythm is the normal heart rhythm in which the electrical impulse originates from the SA node
What is the ECG criteria for normal sinus rhythm?
- 60-100 bpm
- P-P interval regular and R-R interval regular
- P wave upright, uniform and 1 P wave for every QRS complex
- PRI 0.12-0.20 second
- QRS less than or equal to 0.12 seconds. Complex is uniform
What is sinus bradycardia?
Just like sinus rhythm, sinus bradycardia the electrical impulse originates from the SA node but at a slower rate, less than 60/minute
What is the ECG criteria for sinus bradycardia?
- This may be a “normal” rhythm for an individual
- Increased vagal tone due to valsalva or vomiting
- Hypothermia
- Hypothyroidism
- Acute MI
- Increase ICP
- Result of medications
- Beta blockers
- calcium channel blockers
- Digoxin
What is the clinical assessment for SB?
- SB may not result in any changes in a patient’s hemodynamic status
- SB may cause decrease cardiac output and thus hypotension
- Orthostasis
- Mental status changes, dizziness, or syncope due to low cerebral blood flow
- SB may cause symptoms of angina or shortness of breath
What are the nursing interventions for SB?
- If no symptoms, nothing is done
- ABCs
- HOB flat
- Assess hemodynamic response and associated symptoms
- O2 possibly
- IV access
- Atropine to increase HR (IVP for symptomatic patient)
- Pacemaker
What is sinus tachycardia?
Just like sinus rhythm, in sinus tachycardia the electrical impulse originates from the SA node but at a faster rate
What is the ECG crtieria for sinus tachycarida (ST)?
- More than 100bpm
- P-P interval regular and R-R interval regular
- P wave upright, uniform, and 1 P wave for every QRS complex
- PRI 0.12-0.20 seconds
- QRS less than or equal to 0.12 seconds. Complex is uniform
What are the possible causes of sinus tachycardia?
- Exertion
- Pain
- Fever
- Increased sympathetic stimuation: caffeine, tobacco, stress
- Hypovolemia
- Anemia
- Hypoxia
- Hyperthyroidism
What is the clinical assessment for ST?
- Hemodynamic changes may result from decrease in CO related to a decrease in the stroke volume
- Symptoms depend on the rate and the overall cardiac status
- Hypotension
- Orthostasis
- Dizziness or syncope
- Dyspnea
- Development of angina due to increase workload of the heart
What are the nursing interventions for ST?
- ABCs
- Treats underlying cause
- Control pain
- Treat fever
- Decrease stress and anxiety
- Limit intake of caffeine or tabacco products
- Treatments of hypovolemia or anemia
- Meds (goal is to slow HR)
- Beta blocers
- Calcium chennel blockers
What is supraventricular tachycardia (SVT)?
The electrical impulse originates outside the SA node in an ectopic site in either atrium. The rate for SVT is between 200-300 BPM