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13 Cards in this Set

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What are the 3 general causes of Bradyarrhythmias?
***AV node conduction abnormalities
First degree heart block
-Widened PR
Second degree heart block
-Mobitz I, Mobitz II
Third degree heart block
-2:1/3:1/4:1 AV block
Third degree heart block
Describe first degree AV block and some possible causes/treatment
Usually results from slowing of AV conduction. Associated with:
1)increased vagal tone
2)Digoxin/Beta blocker admin
3)Infectious (lyme, viral)
4)Hypothermia
5)Electrolyte (hypo/hyperkal,hypo/hypercal, hypomag)
6)Congenital Heart Dz
7)Rheumatic fever
8)Cardiomyopathy

Treatment is not necessary if CO is maintained
Describe second degree AV block and some possible causes/treatment
1) Mobitz I (Wenkebach)- gradual PR lengthening followed by a dropped QRS. Possible causes include:
1)increased vagal tone
2)Digoxin/Beta blocker admin
3)Infectious (lyme, viral)
4)Hypothermia
5)Electrolyte (hypo/hyperkal,hypo/hypercal, hypomag)
6)Congenital Heart Dz
7)Rheumatic fever
8)Cardiomyopathy
2) Mobitz II - abrupt failure of AV conduction causing a dropped QRS. More serious because it can cause a complete heart block
3) Fixed ratio AV block is when the QRS follows every 2nd, 3rd, or 4th P wave. This is a result of AV or His injury. Can progress to complete heart block.

Treatment is not necessary for Mobitz I, and a pacemaker is required for type II and fixed ratio
Describe third degree AV block and some possible causes/treatment
Third degree heart block is when no atrial impulses are conducted to the ventricles. Atrial rate is normal for persons age, but ventricular rate is slowed (40-55bpm). Possible causes include:
1)Congenital heart disease
2)Open heart surgery
3)cardiomyopathy (Lyme disease)
4)Maternal lupus

Treatment: will require a pacemaker
What is the differential diagnosis for narrow complex tachycardia?
1)Sinus tach - fever, stress, dehydration, anemia
2)Orthodromic Reentrant Tachy - mostly from a concealed bypass tract (AVNRT, Ebsteins anomaly, Transposition of great arteries)
A flutter - atrial surgery, myocarditis, structural heart disease, dilated atria, severe TR
Afib - LAE, WPW, myocarditis
What is the differential for wide complex tachycardia?
1) Vtach - congenital or acquired heart disease resulting in vent. dilataion or hypertrophy, drug ingestion, WPW ART
2) Vfib - Terminal rhythm that develops after hypoxia, ischemia, electrical injury, predisposing factors include WPW and long QT syndrome.
How is a narrow complex tachy treated?
Depends on cause, but usually progresses in the following order:
1) Vagal maneuvers - ice on face/carotid massage
2) Pharmacotherapy - If vagal maneuvers are unsuccessful, then adenosine is used to block AV node to break SVT (AVNRT, WPW ORT, concealed bypass tract ORT). If adenosine works and WPW is not suspected then the child is started on Digoxin to prevent future events. If adenosine reveals WPW, a beta blocker is used because digoxin can slow AV node conduction and speed up accessory pathway conduction causing an ART.
3) Cardioversion - indicated with unstable narrow complex tachy and CHF or hypotension. also used in unstable Aflutter.
What situations justify the use of Adenosine. When is it effective?
Use adenosine first line in narrow complex tachycardias. It will be effective if the AV node is involved.

Adenosine will be ineffective on narrow complex tachy that results from increased automaticity or a reentrant mechanism not involving the AV node. (sinus tach, ectopic atrial tachy, junctional ectopic tachy, aflutter, sinoatrial reentrant tachy)
After cardioversion is done for a narrow complex tachy, what is the next step?
Pt. is started on dig, beta blockers, procainamide, amio, sotalol, or quinidine/dig combo to prevent recurrences. Ideally the patient would be loaded with Dig and then put on procainamide in an attempt to convert the arrhythmia. Load with digoxin because procainamide has vagolytic activity that could increase the ventricular rate and cause acute hemodynamic derioration.
What can be used to convert Afib?
Cardioversion, Quinidine, Procainamide, or amiodarone. Long term maintenance is done with quin or procain.
How is a wide complex tachy treated?
1)Hypotensive patients:
Treat immediately with cardiopulmonary resuscutation and synchronized cardioversion. The sinus rhythm can then be maintained with IV lidocaine or amiodarone.

2)Normotensive patients: treat with IV lidocaine or amiodarone
What is the likely origin of a wide complex bradyarrhythmia?
likely to be escape rhythms from the His bundle or Purkinje system (idioventricular) and are at high risk to progress to complete heart block
When treating SVT, what is the first thing you need to rule out?
WPW