Lecture 10 9/5/24 Flashcards
Which diagnoses fall into the supraventricular tachyarrhythmia category?
-premature supraventricular complexes
-supraventricular tachycardia
-atrial fibrillation
Which diagnoses fall into the ventricular tachyarrhythmia category?
-premature ventricular complexes
-ventricular tachycardia
-ventricular fibrillation
Why are arrhythmias clinically important?
-they can cause clinical signs such as syncope and sudden death
-relentless tachycardia can result in development of myocardial dysfunction
What are the main causes of cardiac related sudden death?
-ventricular tachycardia that progresses to ventricular fibrillation
-severe bradycardia
What are the general approaches to treating tachyarrhythmias and bradyarrhythmias?
-tachyarrhythmias are treated pharmacologically
-bradyarrhythmias are most often treated trough electronic pacing and occasionally medically
What are the two reasons to treat arrhythmias in the short-term?
-if the arrhythmia is associated with clinical signs
-if the patient is at risk of sudden cardiac death and treatment will reduce the risk
Why are arrhythmias not always treated?
-anti-arrhythmic agents can worsen arrhythmias in rare cases
-evidence that anti-arrhythmic therapy decreases mortality is lacking
What are the classifications for anti-arrhythmic drugs and their mode of action?
-Class 1: sodium blockade
-Class 2: beta blockade
-Class 3: potassium blockade
-Class 4: calcium blockade
What are the characteristics of digoxin?
-weak positive inotrope
-vagomimetic effect
-slows AV conduction by impacting the SA node
What are the characteristics of Class 1 and 3 drug usage?
-used to suppress abnormal, spontaneous depolarizations
-act on the myocardium
What are the characteristics of class 2 and 4 and digoxin drug usage?
-used to slow ventricular response to atrial tachyarrhythmia
-act on conduction system
-block conduction at AV node
When is medical therapy indicated for tachycardia?
-persistent tachycardia
-frequent episodes of tachycardia
-frequent “couplets” or “triplets” of premature complexes
Which type of diseases are associated with atrial premature complexes?
diseases that cause atrial enlargement
Which supraventricular tachyarrhythmia is the most commonly treated?
atrial fibrillation
Which agents used to treat SVTA diseases slow AV nodal conduction?
-calcium channel antagonists
-beta-adrenergic antagonists
-digoxin
Which agents used to treat SVTA diseases increase atrial refractory period?
-procainamide
-class 3 agents
-class 1c agents
What are vagal maneuvers?
pressure/massage applied to the ocular globes or carotid sinuses to initiate a reflex that results in vagal discharge with a principal effect on the conduction system
What response is possible when vagal maneuvers are performed on a patient with sinus tachycardia?
gradual slowing
What response is possible when vagal maneuvers are performed on a patient with “accessory pathway” tachycardia?
abrupt termination
What response is possible when vagal maneuvers are performed on a patient with atrial tachycardia?
AV block
When urgently treating supraventricular tachycardia, what are the mainstays of therapy?
-vagal maneuvers
-diltiazem
-esmolol
When chronically treating supraventricular tachycardia, what are the mainstays of therapy?
-digoxin
-diltiazem
-atenolol
Which disease is associated with atrial distention?
atrial fibrillation
What are the two therapeutic strategies for treating atrial fibrillation?
-rate control: patient remains in AFib and drugs are used to slow ventricular response rate
-rhythm control: pharmacologic or electrical conversion to sinus rhythm
When is rate control used to treat AFib?
-when AFib complicates structural heart disease
-when AFib is idiopathic
When is rhythm control used to treat AFib?
in some cases where AFib is idiopathic
What is the main course of therapy for treating ventricular tachyarrhythmias related to extra-cardiac disease?
addressing the non-cardiac, predisposing factors
When is pharmacologic therapy indicated in VTA treatment?
-when associated with clinical signs
-when rate is rapid
What is the treatment hierarchy for VTA?
-lidocaine
-procainamide
-injectable amiodarone
-beta blockade
-DC countershock under GA
Which drugs are used in the chronic management of VTA?
-sotalol
-mexiletine
-amiodarone
-combinations of medications
What are the two etiologic categories of 2nd degree AV block?
-type 1: functional and related to elevated vagal tone
-type 2: intrinsic AV node/AV bundle disease
When does AV block become an important indication for cardiac pacing?
when the patient has high grade 2nd degree or 3rd degree AV block (3:1 AV conduction ratio or greater)
What is the treatment for sick sinus syndrome?
cardiac pacing
