dysrythmias Flashcards
class IA Na blocker mechanism:
slows phase 0 depolarization
class IB Na blocker mechanism:
shortens phase 3 repolarization
class IC Na blocker mechanism:
markedly slows phase 0 depolarization
class II beta-blocker mechanism:
suppress phase 4 depol
class III K+ blocker mechanism:
prolongs phase 3 repol
class IV Ca++ blocker mechanism:
shortens AP
Class IA drug. This drug blocks Na+ channels in their open (activated) or closed (inactivated) states. This drug slows phase 0 depol and suppresses arrhythmias caused by increased normal automaticity. This drug inhibits ectopic and ventricular arrhythmias. This drug is indicated for atrial and ventricular tachyarrhythmias, used to maintain sinus rhythm post cardioversion. What is this drug?
quinidine
contraindications for quinidine:
heart block, SA node dysfunction, cardiogenic shock, sever uncomplicated heart failure, schizophrenia, SLE w/ procainamide
ADRs of quinidine:
arrhythmias, N/V/D, cinchonism, metabolism inhibited by cimetidine, induced by phenytoin, rifampin, barbituates, decreases digoxin clearance
Class IA drug. This drug is a derivative of procaine. Actions similar to quinidine. This drug is metabolized to n-acetylprocainamide (NAPA) which prolongs duration of AP (class III properties). What is the drug?
procainamide
ADRs of procainamide:
hypotension with IV route thus give PO, 25-30% reversible lupus erythematous-like syndrome with chronic use, asystole or ventricular arrhythmias at toxic concentration, depression, hallucination, psychosis
Class IA drug. This drugs actions are similar to quinidine. This drug produces negative inotropic effects, decreasing contractility in LV dysfunction, contraindicated in heart failure, causes peripheral vasoconstriction. What is this drug?
disopyramide.
disopyramide is used to treat?
ventricular arrhythmias
Disopyramide is an alternative to:
procainamide and quinidine
disopyramide ADRs:
anticholinergic sides (urinary retention, blurred vision, dry mouth, constipation), proarrhythmic
Class IB. This drug is the prototype and DOC for emergency treatment of cardiac arrhythmias. This drug shortens phase 3 repolarization and decreases the duration of the action potential. This drug suppresses arrhythmias caused by abnormal automaticity. This drug does not cause a negative inotropic effect. This drug is indicated for ventricular arrhythmias post MI or arising from myocardial ischemia. What is this drug?
Lidocaine
what are the contraindications for lidocaine?
SA disorders. AV block
what are the ADRs for lidocaine?
confusion, slurred speech, drowsiness, parasthesias, agitation, cardiac arrhythmias
Class IB. This drug’s action’s are similar to lidocaine. This drug is indicated for chronic ventricular arrhythmias associated with previous MI. What is the name of this drug?
mexiletine
Class IB. This drug is indicated for tx of ventricular tachyarrhythmias. ADRs for this drug include pulmonary toxicity that can lead to fibrosis. What is this drug?
tocainide
Class IC. questionable safety. This drug blocks Na+ channels and slows phase 0 depolarization. This drug can be oral or IV. This drug is indicated for refractory ventricular arrhythmias. What is this drug?
flecainide
What are the contraindications for flecainide?
CHF (negative inotropic effect)
ADRs for flecainide?
dizziness, blurred vision, HA, nausea, can aggravate pre-existing arrhythmias or induce life-threatening ventricular tachycardia that is resistant to treatment.
This drug has a similar action to flecainide:
propafenone
Class II agents. These drugs diminish phase 4 depolarization. Indications for these drugs are to prevent ventricular arrhythmias post MI, tachyarrhythmias caused by increased sympathetic activity (NE & epi), atrial flutter and fibrillation, AV nodal reentrant tachycardia. What are these drugs?
propranolol, metoprolol, esmolol
Class III agents. These drugs block potassium channels thus prolonging both repolarization and duration of AP thus lengthening effective refractory period. These drugs are indicated for ventricular and supraventricular arrhythmias. What are these drugs and what are their respective routes of administration?
sotolol (betapase)-oral. amiodarone (cordarone,pacerone)-oral&IV. dofetilide.
Class III agent. Potent beta-blocker activity. This drug is effective in preventing arrhythmia recurrence and decreasing mortality in pts with sustained VTACH. The ADR for this drug is torsade de pointes (3-4%). What is this drug?
Sotolol
Class III agent. This drug is indicated for persistent afib and HF or CAD w/ impaired LVF. This drug is restricted to MDs who have completed manufacturer’s training. This drug is a proarrhythmic. What is this drug?9
dofetilide
Class III agent. This drug contains iodine and is structurally related to thyroxine. this drug exhibits class I,II,III, and IV actions. The dominant effect of this drug is prolongation of AP duration and refractory period. This drug possesses antianginal and and antiarrhythmic activity. This drug is indicated for refractory SVT and ventricular tachyarrhythmias. This drug does not reduce incidence of sudden death or prolonged survival in pts w/ CHF. Half-life is several weeks and clinical effects are achieved in around six weeks. What is this drug?
amiodarone
What are the long-term use ADRs of amiodarone?
pulmonary fibrosis, GI intolerance, tremor, ataxia, hyper- or hypothyroidism, neuropathy, muscle weakness, accumulation of iodine leads to blue skin discoloration.
Class IV agents. Ca++ channel blocker. These drugs slow phase 4 depolarization and slowed conduction in tissues dependent on Ca++ currents such as the AV node. These drugs are?
Verapamil (PO). Diltiazem (PO/IV)
Class IV agents (verapamil and diltiazem) are indicated for?
atrial arrhythmias, reentrant supraventricular tachycardia, reducing ventricular rate in atrial flutter and fibrillation, HTN, angina
ADRs for class IV agents (verapamil and diltiazem) are?
hypotension due to peripheral vasodilation. contraindicated in pts with preexisting depressed cardiac fxn due to neg inotropic properties.
This is an endogenous nucleoside that acts at tissues in the lungs , afferent nerves, and platelets:
Adenosine
adenosine pharmacokinetics:
short duration of action (15 sec)
contraindications for adenosine:
2nd and 3rd degree heart block. sick sinus syndrome
adenosine indications:
DOC for abolishing supraventricular tachycardia
adenosine ADRs:
transient facial flushing, chest pain, dyspnea, bronchospasms
Digoxin indications:
control ventricular rate in Afib and Aflutter
Digoxin ADRs:
ectopic ventricular beats –> VTACH/VFIB (treated with lidocaine)
Pt presents with sxs of palpitations, irregular pulse, dizziness, and dyspnea. What is this pt presenting with?
atrial fibrillation
Severe sxs of a fib are?
acute HF, unstable angina, hypotension
two types of afib:
paroxysmal (self-terminating) and persistent (not self terminating)
does acute treatment differ for paroxysmal and persistent afib?
no
General tx of tachycardia:
DCC(direct current cardioversion) for pt who are severely symptomatic or hemodynamically unstable
anticoagulation therapy for afib:
parenteral heparin then transition to oral warfarin, ASA, or dabigatran
IV meds for ventricular rate control:
beta-blockers, diltiazem, or verapamil. amiodarone is typically used when other drugs have failed or cannot be given or when cardioversion is desired in addition to rate control
restoration of normal sinus rhythm is accomplished by?
DCC. chemical cardioversion can be used but is less effective than DCC but may be used when determination of an effective agent is required for long term therapy (procainamide, quinidine)
