Therapeutics: Arrhythmia 3
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The CAST trial showed that what two antiarrhythmic are the only ones to not increase mortality w/ long term use?
Amiodarone and Dofetilide
What two outcomes came from the CASt trial (besides Amiodarone and Dofetilide safety)?
- 1) Don’t treat premature ventricular contraction
- 2) A lot of anti-arrhythmic are toxic
What drugs can cause Sinus Bradycardia?
BB and CCBs
What is the dose of Atropine for a Hemodynamically unstable patient with Sinus Bradycardia?
0.5 mg IV bolus may repeat up to 3 mg (6x)
What are the steps in treating a Hemodynamically unstable patient with Sinus Bradycardia?
- Step 1 - Transcutaneous pacing
- Step 2 - Atropine
- Step 3 - Epinephrine or Dopamine
What is the dose of Epinephrine for a Hemodynamically unstable patient with Sinus Bradycardia?
2-10 mg/min IV
What is the dose of Dopamine for a Hemodynamically unstable patient with Sinus Bradycardia?
2-10 mg/kg/min IV
Would you D/C a BB if a person has 1stdegree HB?
No, maybe just lower the dose, as long as they aren’t symptomatic
What Drugs cause 1st degree HB?
Digoxin or AV nodal blocking drugs (BBs and CCBs)
What is the treatment for 1st degree HB?
How would you treat acute AV Nodal reentry tachycardia?
- Increase vagal tone w/ vagal maneuvers: Valsava, carotid sinus massage
- If doesn’t work: Adenosine 6 mg IV
- If doesn’t work: Adenosine 12 mg IV
What are the side effects of Adenosine?
Flushing, vasodilatation and bronchospasm (short lived)
What is Adenosine?
ATP, very short half life of 10 seconds
What is the AV Nodal reentry tachycardia maintenance treatment?
- Usually BB or CCB (Diltiazem or Verapamil)
- If doesn’t work: Clas 1A, 1C or III antiarrhythmics (most likely III)
- If all else fails: Radiofrequency ablation (80-90% curative)
How do you treat acute AV Accessory Tract Reentry Tachycardia?
- Same as AV nodal:
- Vagal maneuvers
- Then Adenosine 6 mg IV or 12 mg IV
What are the maintenance treatments for AV Accessory Tract Reentry Tachycardia?
- Highly effective: Class IC
- Effective: Class IA
- Effective: Amiodarone
- RF ablation 90-95% curative
What drugs are completely ineffective against AV Accessory Tract Reentry Tachycardia?
BBs, CCBs and Digoxin
Why should you not give CCBs or Digoxin to treat AV Accessory Tract Reentry Tachycardia?
May cause Ventricular fibrillation and kill the patient
What patients should not receive Class 1C drugs for AV Accessory Tract Reentry Tachycardia?
HF, Post MI and low EF/cardiomyopathy
What are the s/s of Atrial fibrillation?
- Impaired effort tolerance
- Some patients asymptomatic
What are the steps for managing Afib?
- Step 1: Control ventricular response – Rate control ( BB, CCB or amiodarone)
- Step 2: Terminate sustained episodes -Cardioversion
- Step 3: Prevent (or reduce) AFib recurrences –CCB , BB or antiarrhythmic
- Step 4: Prevent adverse outcomes –Devices and Anticoagulation
When would we choose to Control ventricular response with a rate control drug in Afib (BB, CCB or Amiodarone)?
Presenting w/ tachycardia
What is Step 1 to controlling Afib?
- Control ventricular response – Rate control ( BB, CCB or amiodarone)
- Acute setting:
- EF >40%: IV BB, diltiazem, or verapamil
- EF <40%: IV digoxin, amiodarone
- Chronic setting:
- EF >40%: Oral BB, diltiazem, verapamil
- EF <40%: Oral BB, digoxin
What is Step 2 to controlling Afib?
- Terminate sustained episodes –Cardioversion
- Usually electric
- Pharmacologic = give antiarrhythmic
- Can be surgical too
What is Step 3 to controlling Afib?
Prevent (or reduce) AFib recurrences –CCB , BB or antiarrhythmic
What is Step 4 to controlling Afib?
- Prevent adverse outcomes –Devices and Anticoagulation
- Antyicoagulant, Anti-platelet or Antithrombotic
- Left Atrial appendage closure
As a minimum all Afib pateitns should be discharged on what drugs?
Rate control drugs: BB or CCB (usually a BB)
When would you choose a CCB over a BB for a Discharged Afib patient?
Bronchospasm, asthma or COPD
Would you choose a BB or CCB for a patient with SHF being discharged with Afib?
BB (CCB CI)
Would you use Digoxin for Cardioversion?
What is Digoxin used for in Afib?
- Vagotonic in AV node
- Rate control – slows heart
- Partially inhibits Na/K- ATPase = increases intracellular Na and Ca = increases contraction
What is the target serum conc. of Digoxin for Afib?
0.8-2 ng/ml ( HF = 0.5-0.9)
What is the first s/s of Digoxin Toxicity?
What disease causes Digoxin toxicity?
What should you monitor when giving Digoxin for Afib?
- HR and rhythm
- Metabolic panel:
- Thyroid panel:
What are common interacting drugs with Digoxin?
amiodarone, verapamil, diltiazem
How should you monitor Digoxin levels for Afib?
- No loading dose: obtain 3-5 days after first dose
- Get a trough dose after that: at least 6-8 hours after last dose
- Dose Change: 5-7 days after change
How long does it take to reach Digoxin SS for ESRD?
The risk of embolism for Cardioversion is higher with drugs or electrical?
Same for both
When would you not send a patient home on an atiarrhythmic after Afib?
If we found the problem and there is low risk of reoccurance
When would you send a patient home on an atiarrhythmic after Afib for certain?
Risk factors dicatate a high likelihood or reoccurance
How long after electrical cardioverson should patient be on therapeutic anticoagulation or antithrombotic therapy?
- 4 weeks after cardioversion
- The decide to continue or not based on CHADS2 score
What anticoagulatns/antithrombotics are used post cardioversion at discharge?
warfarin, apixaban, dabigatran, rivaroxaban
What dose of UHF would you give if a patient is uncoagulated prior to Cardioversion?
80 U bolus followed by 18 U infusion
What are the options for a patient who needs cardioversion but is uncoagulated?
- UHF: 80 U bolus followed by 18 U infusion
- Enoxaparin: 1mg/kg bolus (usually used)
When do we not anticoagulate before Cardioversion?
- Therapeutic INR
- Already taking dabigatran, rivaroxaban, or apixaban
Describe the treatment for a person coming in with AFib < 48 hrs?
- Cardiovert with heparin or full dose LMWH (unless exempt)
- Anticoagulate/Antithrombotic for 4 weeks regardless of baseline stroke risk
- After 4 weeks Anticoagulate/Antithrombotic based on CHADS2 score
Describe the treatment for a person coming in with AFib > 48 hrs
- Unknown duration, or risk of thrombus in atrium:
- Option 1: Anticoagulate/Antithrombotic for 3 weeks before and 4 weeks after conversion, or
- Obtion 2: Obtain TEE and then convert with heparin or LMWH
- For All Options: After 4 weeks Anticoagulate/Antithrombotic based on CHADS2 score
The guidelines suggest Enoxaparin o UFH for anticoagulation before Cardioversion?
UHF, but usually use Enox
What classes of Antiarrhythmics can be used for Cardioverson?
1C and III
What are the Class IC agents used for Cardioverson and can they be used for maintenance?
- Flecainide – also used for maintenance
- Propafenone – also used for maintenance
What are the Class III agents used for Cardioverson and can they be used for maintenance?
- Amiodarone – also used for rate control and maintenance
- Dofetilide – also used for maintenance
- Ibutilide – only use is conversion
What MOA difference does propafenone and flecainide have and what effects does that have?
- propafenone has BB activity
- reduces HR
How do you renally adjust flecainide?
Cut dose in half
What is the cardioverson and maintenance dose for Flecainide?
- cardioverson: 200-300 mg po one time
- maintenance: 50-150 mg TID
How do 1C agents (propafenone and flecainide) cause cardioversion?
Decreasing conduction of electrical impulses
What is the Cardioverson and maintenance dose of Propafenone?
- Conversion: 450-600 mg po once
- Maintenance: 150-300 mg TID
What are the AEs for propafenone and flecainide?
Proarrhythmic and HF
What situation would prompt you to lower the Propafenone dose?
Class III agents work by:
delaying repolarization, prolonging action potential, and decreasing myocardial irritability
What Arrhythmic properties can Amiodarone treat?
Cardioverson, Rate control and Maintenance
What are the doses for Cadrioversion by Amiodarone?
- PO conversion: 600-1800 mg/D until 10 g total
- IV conversion: 6-7 mg/kg over 30-60 min; then 1200-1800 mg/D cont IV
What is the maintenance dose of Amiodarone after Cardioverson?
PO Maintenance: 200-400 mg/D
What is the major downside to amiodarone for cardioversion?
Slow onset, may take a week to convert
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