Clinical Treatment of Arrhythmias Flashcards
Slow arrhythmia
brady arrhythmias
If the rhythm is too slow, where in the conduction system is it affected?
- sinus node
- AV node
- below the av node
Sinus node dysfunctions
- Sinus bradycardia
- sinus arrest/pause
- tachy-brady syndrome
- chronotropic incompetence
Sinus Arrest
Failure of sinus node discharge resulting in the absence of atrial depolarization and periods of ventricular asystole
Bradycardia-Tachycardia (Brady-Tachy) Syndrome
Intermittent episodes of slow and fast rates from the SA node or atria
AV node dysfunctions
- first degree AV block
- Mobitz I 2nd degree AV block (Wenkebach)
1st degree AV block
AV conduction is delayed, and the PR interval is prolonged (> 200 ms or .2 seconds). each atrial signal is conducted to the ventricles (1:1 ratio).
Second-Degree AV Block – Mobitz I (Wenckebach)
Progressive prolongation of the PR interval until a ventricular beat is dropped
-Ventricular rate: irregular
below the AV node dysfunctions
- Mobitz II 2nd degree AV block
- complete heart block
Second-Degree AV Block – Mobitz II
- Intermittently dropped ventricular beats preceded by constant PR intervals
- The infranodal (His bundle) tissue is most commonly the site of Mobitz II block.
Third-Degree AV Block
- No impulse conduction from the atria to the ventricles
- PR interval = variable
- also referred to as complete heart block
When should you be concerned about a bradyarrhythmia pt?
- When the patient is symptomatic, no matter which part of the conduction system is affected.
- When the rhythm is infranodal (below the AV node).
Treatment of bradyarrhythmia?
- Find and treat reversible causes– ischemia/infarction, hypothyroidism, neurologic causes, Lyme disease
- Stop offending medications, if possible: antiarrhythmics, clonidine, lithium, among others.
- Acute treatment for unstable patient: beta-agonists (dopamine or isoproterenol), transcutaneous pacing, temporary transvenous pacing.
- Long term: Permanent pacemaker
Types/origins of tachyarrhythmias
Above ventricle: -Supraventricular Tachycardias (SVT) Ventricles: -Ventricular Tachycardia -Ventricular Fibrillation
Acute treatment of irregular SVT
If unstable: shock
Stable: can control their rates, use antiarrhythmics, or cardioversion
5 C’s of A. Fib management
Cause: Reverse Control Rate antiCoagulation (I know, no C there) Control Rhythm Cure: Ablation
Common causes of A. Fib
Hypertension 14% IHD Mitral valve Disease Alcohol Cardiomyopathies Hyperthyroidism Lone AF 14%
Immediate Tx of A Fib
Cardiovert
Control the Rate
Pharmacological rhythm control in A fib
Less successful
Does not require sedation
Class III agents- ibutilide, amiodarone, dofetilide, sotalol
Class IC agents- flecainide, propafenone
Electrical rhythm control in A Fib
DC Shock 70-90% success
Day procedure in hospital
Needs sedation
T or F: Patients with recurrent AF may require long term maintenance medications to control rhythm
True, especially if they are symptomatic in AF.
When are Class IC agents contraindicated?
in CAD and structural heart disease
Should Patients with a rhythm control agent should still be anticoagulated?
Yes, risk still present for thromboembolism, as rhythm control is not a cure.
T or F: Digoxin controls rate during exercise well
False
Rate control medications
Betablockers Digoxin Verapamil Diltiazem Amiodarone: can be used as a rate-controlling agent, especially in setting of decompensated heart failure.
Which medications control HR during exercise?
Betablockers and rate limiting Ca Antagonists
T or F: Use of medications in combination can develop heart block
True
Tx strategies for atrial flutter
- Similar to A Fib
- Catheter ablation more successful than medications, 95% cure rate
- with successful catheter ablation, anticoagulation no longer necessary
- Lower ablation risk when compared to A fib
List other SVT categories
- AV nodal reentrant tachycardia (circuit within the AV node): most common, accounts for ~65% of regular SVTs (not including AF/flutters).
- Accessory pathway-mediated tachycardias: abnormal connection between atrium and ventricle.
- Focal atrial tachycardias: least common, abnormal focus of atrial tissue with enhanced automaticity– a “hotspot”.
Tx options for other SVTs
- Nonpharmacologic maneuvers: vagal maneuvers.
- Pill in pocket: Medication only with symptoms.
- Long term: beta blockers, calcium channel blockers to block AV node, Class I antiarrhythmics to suppress hotspots or premature beats that are triggers for tachycardia.
- Ablation
What are the 2 types of arrhythmias?
Tachy- and bradyarrhythmia
What is chronotropic incompetence
inability to mount age-appropriate HR with exercise
An SVT can be subdivided into those that are _________________.
irregular and those that are regular.
Irregular SVT can be broken down into what 3 types?
-atrial fibrillation, where there are no discrete P waves
Regular SVTs have what P to QRS ratio?
1:1, (sometimes can’t see p waves)
Acute treatment of regular SVT
adenosine
T or F: Cardioversion can be achieved either with drugs or electricity
True, Drugs are less successful but do not require sedation .
T or F: atrial flutter Can be more difficult to rate or rhythm control than AF
True
What is the most common SVT?
AV nodal reentrant tachycardia, circuit w/in the AV node
What is the least common SVT?
Focal atrial tachycardias
If pt has coronary artery disease, 90% of the time the wide complex tachycardia is _______
Ventricular tachyarrhythmia
What is the acute Tx approach for stable ventricular Tachyarrhythmias?
-Medications: Amiodarone Lidocaine Procainamide -Treat underlying causes
What is the acute Tx approach for UNstable ventricular Tachyarrhythmias?
- SHOCK
- Treat underlying causes
- Medications
T or F: If there is structural heart disease with the ventricular arrhythmia, then they most likely will require a defibrillator.
True
First line of therapy for ventricular tachyarrhythmias?
Ablation and medications are first line therapy , ICDs are sometimes contraindicated
When is a defibrillator needed for VTs?
- Secondary prevention: When the patient has had a sudden cardiac arrest due to VT or VF without a reversible cause (ischemia, drugs, electrolytes).
- Primary prevention: When the patient has not had a cardiac arrest but is at significant risk.
What is the difference b/t the leads of a pacemaker and an ICD?
ICD leads have coils
Sudden Cardiac Death (SCD) prognosis
Only one-third of SCD cases are resuscitated and 10% survive to leave the hospital, many with morbidities
The go to treatment for Any unstable tachyarrhythmia
SHOCK
How can adenosine help dx SVT?
helps you see the P wave