Caring for Patients with Atrial Fibrillation

Question 1

cardiac arrhythmias are a frequent problem in clinical
practice
— occurring in up to –% of patients treated with digoxin
— –% of anesthetized patients
— over –% of patients with acute myocardial infarction (MI)

Answer 1

25
50
80

Question 2

arrhythmias may require treatment
— rhythms that are too rapid, too slow, or asynchronous can

Answer 2

reduce cardiac output

Question 3

some arrhythmias can precipitate more serious or even
lethal rhythm disturbances
— e.g. early premature ventricular depolarizations can
precipitate —
— in such patients, — drugs can be life saving

Answer 3

ventricular fibrillation
antiarrhythmic

Question 4

Dangers of Antiarrhythmics
— the hazards of antiarrhythmic drugs has led
to a continual reevaluation of their relative
risks and benefits
* in particular the fact that they can precipitate
lethal — in some patients
— in general, treatment of asymptomatic or
minimally symptomatic arrhythmias should
be …

Answer 4

arrhythmias
avoided

Question 5

— are
common in patients recovering from MI

Answer 5

premature ventricular contractions (PVCs)

Question 6

• increased numbers of PVCs are associated with an
  increased risk of

Answer 6

sudden death
» therefore, treat PVCs?

Question 7

— Cardiac Arrhythmia Suppression Trial (CAST)
* premature ventricular contractions (PVCs) are
common in patients recovering from MI
* increased numbers of PVCs are associated with an
increased risk of sudden death
» therefore, treat PVCs?

• (2) treated patients had
  significantly increased mortality compared to
  untreated patients

Answer 7

flecainide and encainide

Question 8

• therefore, the decision to initiate any form of
  — drug therapy should be predicated on
  the knowledge (or strong assumption) that benefits
  outweigh the risks
• — is no longer available for use

Answer 8

antiarrhythmic
encainide

Question 9

Treatments
— arrhythmias can be treated with drugs or
non-pharmacologic therapies
(4)

Answer 9

• pacemakers
• cardioversion
• catheter ablation
• surgery

Question 10

some arrhythmias should not be treated
(e.g. —)

Answer 10

CAST

Question 11

symptoms due to arrhythmias
(2)

Answer 11

• asymptomatic (benefit vs. risk?)
• palpitations (nothing to one person, debilitating
  to other)

Question 12

choose therapeutic approaches
* e.g. atrial fibrillation:
* to use drugs or not?
(3)

Answer 12

decrease ventricular rate,
restore sinus rhythm,
anticoagulated

Question 13

Principles of Antiarrhythmic Therapy
* Minimize Risk
— anti-arrhythmic drugs can cause —
— monitor — concentrations
— – interactions
— patient-specific contraindications

Answer 13

arrhythmias
plasma
drug

Question 14

patient-specific contraindications
* heart failure and —
* amiodarone can cause (2)

Answer 14

dronedarone
interstitial lung disease
and pulmonary fibrosis (what about COPD?)

Question 15

Signal Propagation through the Heart
— the electrical impulse that triggers a normal cardiac
contraction at regular intervals is in the —
* pacemaker cells spontaneously depolarize at a frequency of – beats per minute
— this impulse spreads rapidly through the atria and enters the —
* the AV node is normally the only conduction pathway between
the —
— conduction through the AV node is slow, requiring about —
* this delay provides time for atrial contraction to …

Answer 15

sinoatrial (SA) node
60-100
atrioventricular (AV) node
atria and ventricles
0.15 sec
propel blood into the ventricles

Question 16

Electrophysiology of Normal Cardiac
Rhythm
* Signal Propagation through the Heart
— the impulse then propagates through the
— system and invades all parts of
the —
— ventricular activation is complete in less
than —
— contraction of all of the ventricular muscle is
— and — effective

Answer 16

His-Purkinje
ventricles
0.1 sec
synchronous, hemodynamically

Question 17

Signal Propagation through the Heart
— on the electrocardiogram
* the PR interval is a measure of …
* the QRS duration indicates the …
» i.e. the — conduction time
* the QT interval reflects the …

Answer 17

conduction time from atrium to
ventricle
time required for all of the ventricular cells to be activated
intraventricular
duration of the ventricular action potential

Question 18

arrhythmias consist of cardiac depolarizations that deviate
from this normal propagation in one or more aspects
* there is an abnormality in (3)

Answer 18

the site of origin of the impulse,
its rate or regularity,
or its conduction

Question 19

skipped
many factors can precipitate or exacerbate
arrhythmias
(lots)

Answer 19

• ischemia, hypoxia, acidosis or alkalosis,
  electrolyte abnormalities, excessive
  catecholamine exposure, autonomic influences,
  drug toxicity (e.g. digoxin or antiarrhythmic
  drugs), overstretching of cardiac fibers, and the
  presence of scarred or otherwise diseased tissue

Question 20

all arrhythmias result from
(3)

Answer 20

• (1) disturbances in impulse formation
• (2) disturbances in impulse conduction
• or (3) both

Question 21

ARRHYTHMIA RESOURCES
(7)

Answer 21

▪ Normal Rhythm
▪ Bradycardia
▪ Heart Block
▪ Atrial Tachycardia
▪ Atrial Fibrillation
▪ Ventricular Tachycardia
▪ Ventricular Fibrillation

Question 22

Atrial fibrillation (AFib)
* characterized by

Answer 22

disorganized, rapid, and
irregular atrial activation with loss of atrial
contraction and with an irregular ventricular
rate that is determined by AV nodal conduction

Question 23

AFib
the ventricular rate tends to be rapid and
variable, between — beats/min, but
in some patients, it may exceed — beats/min

Answer 23

120 and 160
200

Question 24

AFib
patients with high vagal tone or AV nodal
conduction disease may have

Answer 24

slow ventricular
rates

Question 25

Types of AFib * Paroxysmal AFib — “paroxysm” = — episodes that start spontaneously and stop within -- days of onset — often initiated by — catheter ablation that isolates these foci usually abolishes ---, although some patients also have initiating foci in other locations. ATRIAL FIB

Answer 25

sudden attack or worsening 7 small reentrant or rapidly firing foci in sleeves of atrial muscle that extend into the pulmonary veins (PV) paroxysmal AF

Question 26

Persistent AFib — some patients progress over --- from paroxysmal to persistent AFib — persistence of the AFib is likely facilitated by (2) atrial abnormalities, particularly --- that (2) — long-standing persistent AFib (>1 year), significant fibrosis is usually present and it is difficult to restore and maintain ---

Answer 26

years structural and electrophysiologic fibrosis, uncouples atrial fibers promoting reentry and focal automaticity sinus rhythm

Question 27

Epidemiology * AFib is a major --- problem * AFib is the most common --- * Prevalence increases with ---

Answer 27

public health sustained arrhythmia age

Question 28

Prevalence increases with age — >95% of AFib patients are >-- years of age — prevalence by age 80 is ~--% — lifetime risk of developing AFib for men 40 years old is ~--% — lifetime risk of developing AFib for women 40 years old is ~--%

Answer 28

60 10 25 23

Question 29

ATRIAL FIBRILLATION ▪ Risk Factors (8)

Answer 29

* age * prior heart attack or heart disease * hypertension * diabetes mellitus * obesity * sleep apnea * excessive alcohol * smoking

Question 30

Risk of Sequela * AFib is also associated with a risk of developing --- and vice-versa — patients with --- have an increased risk of developing AF * AFib increases the risk of stroke by fivefold and is estimated to be the cause of ---% of strokes * AFib increases the risk of --- and silent strokes detected by MRI

Answer 30

heart failure 25 dementia

Question 31

ATRIAL FIBRILLATION ▪ Signs & Symptoms (6)

Answer 31

* irregular and rapid heartbeat — wearables helping to identify * heart palpitations or rapid thumping inside the chest * dizziness, sweating and chest pain or pressure * shortness of breath or anxiety * tiring more easily when exercising * fainting (syncope)

Question 32

Sequela (5)

Answer 32

* dizziness/falls * stroke — 5X increase in risk * chronic fatigue * additional arrhythmias * heart failure

Question 33

ATRIAL FIBRILLATION ▪ Treatments * Pharmacotherapy (5)

Answer 33

— beta blockers, digoxin, calcium channel blockers or amiodarone * slow heart rate — anticoagulants (covered elsewhere in course) * prevent stroke

Question 34

ATRIAL FIBRILLATION ▪ Treatments Electrical Cardioversion

Answer 34

— return heart to sinus rhythm

Question 35

ATRIAL FIBRILLATION ▪ Treatments Surgery (2)

Answer 35

— catheter ablation — pacemaker

Question 36

Singh/Vaughan-Williams (MechanismBased) Classification LEAD

Answer 36

L * Na+ channel blockade (Class 1A-C) — lidocaine E * blockade of sympathetic autonomic effects on the heart (Class 2) — esmolol A * prolongation of action potential duration and the effective refractory period (Class 3) — amiodarone D * Ca++ channel blockade (Class 4) — diltiazem

Question 37

Antiarrhythmic Therapy for AFib * Class 1 agents — sodium channel–blockers *(4) — options for subjects without significant --- — but (2) effects warrant avoidance in patients with coronary artery disease or heart failure

Answer 37

lidocaine, flecainide, propafenone, disopyramide structural heart disease negative inotropic and proarrhythmic

Question 38

ANTIARRHYTHMIC DRUGS ▪ Antiarrhythmic Therapy for AFib * Class 2 (β-adrenergic blockers) and Class 4 (calcium channel blockers) Agents — Class 2 b-blockers: (5) — Class 4 Ca++ channel blockers: (2) — help control ventricular rate by --- — improve symptoms — possess a low-risk profile — but have low efficacy for preventing AFib episodes

Answer 38

esmolol, atenolol, metoprolol, propranolol, sotalol diltiazem, verapamil slowing AVnodal conduction

Question 39

Antiarrhythmic Therapy for AFib * Class 3 Agents — potassium channel blockers prolonging action potential duration * (4) — --- should be initiated only in a hospital with ECG monitoring * --- worthy of same approach — dronedarone increases mortality in patients with --- — all of these agents have modest efficacy in patients with --- * ~---% will benefit

Answer 39

amiodarone, dronedarone, dofetilide, sotalol dofetilide sotalol heart failure paroxysmal AFib 30–50

Question 40

Antiarrhythmic Therapy for AFib * Class 3 Agents — amiodarone is more effective, maintaining sinus rhythm in approximately two-thirds of patients * it can be administered to patients with (2) * but, over --% of patients experience amiodarone-related toxicities during long-term therapy

Answer 40

heart failure and coronary artery disease 40

Question 41

Antiarrhythmic Treatments * Pacemakers — modern pacemakers are more resistant to --- — but, caution is required when using ---

Answer 41

electromagnetic interferences electrical devices (e.g., ultrasound and electric scalpels)

Question 42

Antiarrhythmic Treatments Drug Interactions — cytochrome P450-mediated (GI tract, liver) (2) — organic cation transporter (kidney) (2)

Answer 42

* amiodarone, diltiazem, verapamil * macrolide antibiotics (erythromycin, azithromycin, clarithromycin) * dofetilide * trimethoprim (e.g. sulfamethoxazole-trimethoprim)

Question 43

Other Drugs That Might Be Used * anxiolytics: — can be useful to lessen --- that may come from anticipation of a dental procedure * perhaps prevent/reduce increased release of --- that can exacerbate AFib or other arrhythmias — (3) * analgesics — (2) — interfere with --- that are highly bound to ---

Answer 43

stress and anxiety catecholamines diazepam, alprazolam, lorazepam, etc non-steroidal anti-inflammatory drugs (NSAIDs) and aspirin anticoagulants plasma proteins (e.g. warfarin)

Question 44

Other Drugs That Might Be Used * antibiotics (3)

Answer 44

— macrolide antibiotics (e.g. erythromycin, azithromycin, clarithromycin) — trimethoprim (e.g. sulfamethoxazoletrimethoprim) — fluoroquinolones (e.g. ciprofloxacin, ofloxacin, levofloxacin)

Question 44

— trimethoprim (e.g. sulfamethoxazoletrimethoprim) (1)

Answer 44

* can inhibit the organic cation transporter in the kidney to inhibit renal elimination of some drugs

Question 44

— macrolide antibiotics (e.g. erythromycin, azithromycin, clarithromycin) (1)

Answer 44

* can significantly inhibit cytochromes P-450 in liver and GI tract

Question 45

— fluoroquinolones (e.g. ciprofloxacin, ofloxacin, levofloxacin) (2)

Answer 45

* many potential adverse effects * can inhibit cytochromes P-450 and some can affect cardiac ion currents