Antidysrhythmics Flashcards
Steps of Normal Heart Contraction
- Ca2+ influx in SA and AV nodes starts AP
- Na+ influx (depolarization) in ventricular muscle cells
- K+ efflux (repolarization) ends AP
Describe Heart Contraction
AP generation that leads to contraction of the myocardial muscle
Arrhythmia
“no rhythm”
Asystole
no heartbeat
4 Types of Dysrhythmias
- Tachdysrhythmias
- Bradydysrhythmias
- Supraventricular Tachycardia
- Ventricular Tachycardia
Tachydysrhythmias
- increased HR
- common
Bradydysrhythmias
- HR is slowed
Supraventricular Tachycardia
- 120-250 bpm
- AV block desirable
Paroxysmal SVT
- episodic
- sudden
- returns to normal w/in 24 hrs
Persistent SVT
- longer than 7 days
- treatment is needed
Permanent SVT
- lasts more than a year despite treatment
Atrial Fibrillation
most common
Ventricular Tachycardia
- ventricular muscle problem (non sustained <30sec or sustained >30sec)
- more dangerous
Causes of Dysrhythmias
- ischemic heart disease
- myocardial infarction
- cardiomyopathy
- myocarditis
- electrolyte imbalances
Symptoms of Dysrhythmias
- palpitations dizziness
- fainting
- dyspnea
- *sometimes asymptomatic
How do Antidysrhythmics work?
- most suppress abnormal electrical impulse formation or conduction
Class I MOA
- block sodium channels
- stop depolarization
Class II MOA
- B Blockers
- this stops CA from releasing and decreases cell activity
- block SNS stimulation (AV block)
Class II Indications
- supra ventricular and ventricular dysrhythmias
Class II Example
Metoprolol
Class III MOA
- K channel blockers
- prolongs repolarization and therefore AP
- extends refractory period
Class III Example
Amioderone- very effective
Amioderone Adverse Effects
- 75% serious problems
- 10% die
Amioderone Indications
- ventricular tachycardia or fibrillation, atrial fibrillation, or flutter
- if resistant to other drugs
- sustained ventricular tachycardia
Class IV MOA
- CCBs
- reduce cell electrical activity
- inhibits Ca cell entry
- act on AV node- reduce conduction velocity (Av block)
Class IV Examples
- Diltiazem
- Verapamil
Class IV Indication
- paroxysmal SVT
- rate control
not for ventricular dysrhythmics
Adverse Effect of All Antidysrhythmics
dysrhythmia
Digoxin MOA
- AV block
- slows HR
Adenosine MOA
- slows conduction through the AV node (AV block)
- convert supraventricular tachycardia to sinus rhythm
Adenosine Adverse Effects
- may cause asystole for a few seconds
- dysrhythmias
Adenosine 1/2 Life and and Route
- short (10-20 sec)
- fast IV push
Adverse Effects of Dysrhythmics to Watch Out For
- SOB
- Edema
- Dizziness
- Syncope (fainting)
- toxicity
Patient Teaching for Antidysrhythmics
- pt to take radial pulse for 1 min (report<60)
Therapeutic Responses to Monitor For
- decrease BP
- decrease edema
- regular pulse rate
- pulse rate w/o major irregularities
- improved CO
