Cardiac Rhythm Disturbances Flashcards
Instability as related to cardiac rhythm d turbances means that the dysrhythmia is
(1) impairing perfusion and threatening vital organ function
( 2) has the potential to deteriorate into cardiac arrest
most common bradycardia
- sinus bradycardia
- junctional rhythm
less commonly, idioventricular rhythm
Atrial fibrillation or flutter with slow ventricular response are uncommon; these rhythms are usually seen in patients
experiencing significant conduction system disease,
ssick sinus syndrome
suffering from excessive AV node blocking medications.
If the patient is unstable, the vast majority of AV blocks
third-degree heart block
followed much less frequently by second-degree AV block
If the patient is stable, most frequently seen
- second-degree type I AV block
third-degree AV block is less common
second-degree type II AV block is quite rare.
Atropine MOA
enhances the automaticity of the sinoatrial (SA) node and p tiates conduction through the AV node by direct vagolytic activity.
β-Adrenergic agents MOA
chronotropic and inotropic cardiac activity,
as well as enhancing electrical conduction within the AV node and infranodal system,
thus their potential to produce ischemia and ectopy
Glucagon
inotropic and chronotropic cardiac activity independent of the β-adrenergic receptors.
Glucagon is primarily used for bradycardias due to cardiotoxicity from β-blocker or calcium channel–blocker overdose.
most appropriate pacing method for the acutely symptomatic patient
Transcutaneous pacing
Atropine
0.5- to 1.0-milligram IV push; may repeat every 3–5 min until desired heart rate is achieved or to total dose of 3 milligrams
Most effective for bradydysrhythmias due to sinus and higher AV nodal disease
Dopamine
IV infusion at rate 2–20 micrograms/kg/min; titrate to desired heart rate
May precipitate myocardial ischemia and ectopy
Epinephrine
IV infusion at rate 2–10 micrograms/min; titrate to desired heart rate
May precipitate myocardial ischemia and ectopy
Glucagon
3–10 milligrams IV infused over 1–2 min, followed by an IV continuous infusion of 1–5 milligrams/h
Used for cardiotoxicity associated with β-blocker and calcium channel–blocker overdose
Limited human data are available supporting its use Nausea and vomiting are often limiting side effects Tachyphylaxis may develop during infusion
Adenosine
6-milligram rapid IV push;
if after 1–2 min the dysrhythmia persists,
repeat rapid IV push with 12 milligrams;
may repeat once more if dysrhythmia persists
Effective in terminating narrow QRS complex reentrant tachydysrhythmias involving the AV node
Verapamil
5–10 milligrams IV bolus over 2–3 min;
if after 15 min the dysrhythmia persists,
may repeat with dose of 10 milligrams
Effective in terminating narrow QRS complex reentrant tachydysrhythmias involving the AV node and reducing ventricular rate in atrial fibrillation or flutter