Download 1st Degree AV Block

Brady Arrhythmia
M.R Samieinasab, MD,
Interventional Electrophysiologist
Chamran Heart Hospital
Definition: HR slower than 60/min
Normal Impulse Conduction
Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers
Symptom Basis
Bradycardia
/asystole
AV dyssnchrony


CO2
 venous pressures
 cardiac output


 perfusion
O2
‘Pacemaker
Syndrome’


Symptoms
Symptoms
CO2
O2
Symptoms of Bradycardia
• Usually occurs when heart is not pumping enough blood
to meet body's needs. This often happens when the heart
rate is very slow or remains slow for a long period of time.
• Related to organ hypo-perfusion and include:
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–
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Dizziness or lightheadedness
Fainting (syncope) or near-fainting
Tiredness (fatigue)
Shortness of breath
Palpitations
Chest pain (angina)
Increased difficulty exercising
Confusion or difficulty concentrating
Some people with bradycardia do not have symptoms
Yan, Gan-Xin (2011). Management of Cardiac Arrhythmias. New York: Springer Science. pg.
307.
Classifications of Bradyarrhythmias
• There are two types of bradyarrhythmias
– Those related to problems with impulse formation
Sinus node
AV node
– Those related to problems with impulse conduction
Classification of Bradyarrhythmias
• Problems with Impulse Formation
– Sinus Arrest
– Sinus Bradycardia
– Chronotropic Incompetence
– Brady/Tachy syndrome
Practice Rhythm Strips
Sinus Bradycardia
• Sinus Node depolarizes very slowly
• If the patient is symptomatic and the rhythm is persistent
and irreversible, may require a pacemaker
Sinus Bradycardia
Causes
• Hypothyroidism
• Drugs
• During vomiting or vasovagal syncope
• Increased intracranial pressure
• Hypoxia, hypothermia
• Infections
• Depression
• Jaundice
Practice Rhythm Strips
Sinus Pause/Arrest
Rate
Varies
P-P Regularity
Irregular
R-R Regularity
Irregular
P wave
Present, except during pause
P:QRS Ratio
1:1, associated
PR Interval
Normal
QRS Width
Normal
Sinus Node Exit Block
Rate
Varies
P-P Regularity
Irregular
R-R Regularity
Irregular
P wave
Present, except during dropped beats
P:QRS Ratio
1:1, associated
PR Interval
Normal
QRS Width
Normal
Rate
40-60bpm
P-P Regularity
None, or Regular if antegrade or retrograde
R-R Regularity
Regular
P wave
Variable (none, antegrade, or retrograde)
P:QRS Ratio
None, or 1:1 if antegrade or retrograde
PR Interval
None, short, or retrograde
QRS Width
Normal
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•
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
Interpretation?
50-75 bpm
Phasic variations
normal
0.12 s
0.10 s
Sinus Arrhythmia
Sinus Arrest
• Failure of sinus node discharge
• Absence of atrial depolarization
• Periods of ventricular asystole
• May be episodic as in vaso-vagal syncope, or carotid sinus
hypersensitivity
– May require a pacemaker
Chronotropic Incompetence
The heart rate is unable to change in response
to the body’s metabolic demand.
Griffen, Brian P. (2011). Manual of Cardiovascular Medicine. Philadelphia: Lippincott,
Williams, and Wilkins. (pg. 79).
• Normal, healthy heart is able to increase peak cardiac output by up to 5x
baseline with exercise
• In chronotropic incompetence, patient may only be able to double cardiac
output over baseline
• An increase in stroke volume only may limit activity and
cause symptoms
Heart
Rate
130 bpm
Running
95 bpm
Walking
60 bpm
Sleeping
Activity
1
Nordlander R, Hedman A, Phersson SK. Rate responsive pacing and exercise capacity—a comment. PACE.
1989;12:749-751.
2
Stone J, Crossley G. Current sensor technology for heart rate modulation by artificial pacing. Clinical
Electrophysiology Review. 1999;3:10-14
Practice Rhythm Strips
Brady/Tachy Syndrome
• Intermittent episodes of slow and fast rates from the SA node
or atria
• Brady < 60 bpm
• Tachy > 100 bpm
• Sinus Node Disease
– Patient may also have periods of AF and chronotropic incompetence
– Most common pacing indication
Curtis, Anne B. (2011). Fundamentals of Cardiac Pacing. Massachusetts: John and Bartlett
Publishers. (pg. 24).
High Vagal Tone
• Usually in the young
• Normal heart rate response during exercise
• Normal intrinsic heart rate
• Bradycardia may be severe enough to cause syncope
(especially in familial form)
Bradycardia Classifications
• Problems with Impulse Conduction
– Exit Block
– First Degree AV block
– Second Degree AV block
• Mobitz Type 1 – Wenckebach
• Mobitz Type 2
– Third Degree AV block – Complete heart block
– Bifasicular/Trifasicular block
Exit Block
• Transient block of impulses from the SA node
– Sinus Wenckebach is possible, but rare
• Pacing is rare unless symptomatic, irreversible, and
persistent
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
Interpretation?
60 bpm
Regular
Normal
0.36 s
0.08 s
1st Degree AV Block
First-Degree AV Block
• PR interval > 200 ms
• Delayed conduction through the AV Node
- Example shows PR Interval = 320 ms
- Not an indication for pacing
- Some consider this a normal variant (not an arrhythmia)
Wenckebach Block
Second-Degree AV Block – Mobitz I
• Progressive prolongation of the PR interval until there is
failure to conduct and a ventricular beat is dropped
• Otherwise known as Wenckebach block
– Usually not an indication for pacing
Second-Degree AV Block – Mobitz II
• Regularly dropped ventricular beats
– 2:1 block (2 P-waves for every 1 QRS complex)
– Atrial rate = 75 bpm, Ventricular rate = 42 bpm
• A “high grade” block, usually an indication for pacing
– May progress to third-degree, or Complete Heart block (CHB)
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Rate?
Regularity?
P waves?
PR interval?
QRS duration?
40 bpm
Regular
Nl, 2 of 3 no QRS
0.14 s
0.08 s
Interpretation? Advanced AV Block
Third-Degree AV Block
Complete Heart Block
• No impulse conduction from the atria to the ventricles
– Atrial rate = 130 bpm, Ventricular rate = 37 bpm
– Complete A – V disassociation
– Usually a wide QRS as ventricular rate is idioventricular
Fascicular Block
Right bundle branch
block and left
posterior hemiblock
Right bundle branch block
and left anterior hemiblock
Complete left bundle
branch block
Trifascicular Block
• Complete block in the right bundle branch, and
• Complete or incomplete block in both divisions of the left
bundle branch
• Identified by EP Study
Knowledge Checkpoint
Knowledge Checkpoint
.
• Diagnostic Test for Bradyarrhythmia:
• EKG
• Holter Monitoring
• Implantable Loop Recorder
• EPS
Sinus Bradycardia
Investigation of
the Site of AV
Conduction
Disease by
Electrophysiologi
c Study (EPS)
Management :
• Drug
• Electrolyte Imbalance
• Hypothyroidism
• Post MI
• PPM Implantation
Classification of Recommendations
and Level of Evidence
Class I
Class IIa
Class IIb
Class III
Benefit >>> Risk
Benefit >> Risk
Additional studies with
focused objectives
needed
Benefit ≥ Risk
Additional studies with
broad objectives needed;
Additional registry data
would be helpful
Risk ≥ Benefit
No additional studies
needed
Procedure/ Treatment
SHOULD be
performed/
administered
IT IS REASONABLE to
perform procedure/
administer treatment
Procedure/Treatment
MAY BE CONSIDERED
Procedure/Treatment
should NOT be
performed/administered
SINCE IT IS NOT
HELPFUL AND MAY
BE HARMFUL
Level of Evidence:
Level A:
Data derived from multiple randomized clinical trials or meta-analyses
Multiple populations evaluated;
Level B:
Data derived from a single randomized trial or nonrandomized studies
Limited populations evaluated;
Level C:
Only consensus of experts opinion, case studies, or standard of care
Very limited populations evaluated
Common Pacing Indications
• The AHA and ACC have defined the indications for pacing
based on the underlying arrhythmia
• At its simplest patients with the following conditions are
commonly indicated for a pacemaker:
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Symptomatic bradycardia
Sinus Node Disease (SND), or Sick Sinus Syndrome
Complete Heart Block
Chronotropic Incompetence
• Usually excludes “low grade” blocks (Mobitz I and 1st
degree)
Epstein et al. “ACC/AHA/HRS Guidelines for Device-Based Therapy.” JACC Vol. 51, No. 21, 2008.
Sinus Node Dysfunction
I IIa IIb III
Permanent pacemaker implantation is indicated for sinus
node dysfunction (SND) with documented symptomatic
bradycardia, including frequent sinus pauses that produce
symptoms.
I IIa IIb III
Permanent pacemaker implantation is indicated for
symptomatic chronotropic incompetence.
I IIa IIb III
Permanent pacemaker implantation is indicated for
symptomatic sinus bradycardia that results from required
drug therapy for medical conditions.
Sinus Node Dysfunction (cont’d)
I IIa IIb III
Permanent pacemaker implantation is reasonable for SND
with heart rate less than 40 bpm when a clear association
between significant symptoms consistent with bradycardia
and the actual presence of bradycardia has not been
documented.
I IIa IIb III
Permanent pacemaker implantation is reasonable for
syncope of unexplained origin when clinically significant
abnormalities of sinus node function are discovered or
provoked in electrophysiological studies.
I IIa IIb III
Permanent pacemaker implantation may be considered in
minimally symptomatic patients with chronic heart rate
less than 40 bpm while awake.
Sinus Node Dysfunction (cont’d)
I IIa IIb III
Permanent pacemaker implantation is not indicated for
SND in asymptomatic patients.
I IIa IIb III
Permanent pacemaker implantation is not indicated for
SND in patients for whom the symptoms suggestive of
bradycardia have been clearly documented to occur in the
absence of bradycardia.
I IIa IIb III
Permanent pacemaker implantation is not indicated for
SND with symptomatic bradycardia due to nonessential
drug therapy.
Acquired Atrioventricular Blocks
in Adults
I IIa IIb III
Permanent pacemaker implantation is indicated for thirddegree and advanced second-degree atrioventricular (AV)
block at any anatomic level associated with bradycardia
with symptoms (including heart failure) or ventricular
arrhythmias presumed to be due to AV block.
I IIa IIb III
Permanent pacemaker implantation is indicated for thirddegree and advanced second-degree AV block at any
anatomic level associated with arrhythmias and other
medical conditions that require drug therapy that results in
symptomatic bradycardia.
Acquired Atrioventricular Blocks
in Adults (cont’d)
I IIa IIb III
Permanent pacemaker implantation is indicated for thirddegree and advanced second-degree AV block at any
anatomic level in awake, symptom-free patients in sinus
rhythm, with documented periods of asystole greater than
or equal to 3.0 seconds or any escape rate less than 40
bpm, or with an escape rhythm that is below the AV node.
I IIa IIb III
Permanent pacemaker implantation is indicated for thirddegree and advanced second-degree AV block at any
anatomic level in awake, symptom-free patients with atrial
fibrillation (AF) and bradycardia with 1 or more pauses of at
least 5 seconds or longer.
Acquired Atrioventricular Blocks
in Adults (cont’d)
I IIa IIb III
Permanent pacemaker implantation is indicated for thirddegree and advanced second-degree AV block at any
anatomic level after catheter ablation of the AV junction.
I IIa IIb III
Permanent pacemaker implantation is indicated for thirddegree and advanced second-degree AV block at any
anatomic level associated with postoperative AV block that
is not expected to resolve after cardiac surgery.
Acquired Atrioventricular Blocks
in Adults (cont’d)
I IIa IIb III
Permanent pacemaker implantation is indicated for
asymptomatic persistent third-degree AV block at any
anatomic site with average awake ventricular rates of 40
bpm or faster if cardiomegaly or left ventricular (LV)
dysfunction is present or if the site of block is below the AV
node.
I IIa IIb III
Permanent pacemaker implantation is indicated for secondor third-degree AV block during exercise in the absence of
myocardial ischemia.
Acquired Atrioventricular Blocks
in Adults (cont’d)
I IIa IIb III
Permanent pacemaker implantation is reasonable for
persistent third-degree AV block with an escape rate
greater than 40 bpm in asymptomatic adult patients
without cardiomegaly.
I IIa IIb III
Permanent pacemaker implantation is reasonable for
asymptomatic second-degree AV block at intra- or infraHis levels found at electrophysiological study.
I IIa IIb III
Permanent pacemaker implantation is reasonable for
first- or second-degree AV block with symptoms similar
to those of pacemaker syndrome or hemodynamic
compromise.
Acquired Atrioventricular Blocks
in Adults (cont’d)
I IIa IIb III
Permanent pacemaker implantation is reasonable for
asymptomatic type II second-degree AV block with a
narrow QRS. When type II second-degree AV block
occurs with a wide QRS, including isolated right bundlebranch block, pacing becomes a Class I
recommendation. (See Section 2.1.3, “Chronic
Bifascicular Block” of the full text guidelines.)
Acquired Atrioventricular Blocks
in Adults (cont’d)
I IIa IIb III
Permanent pacemaker implantation is not indicated for
asymptomatic first-degree AV block. (See Section 2.1.3,
“Chronic Bifascicular Block” of the full-text guidelines.)
I IIa IIb III
Permanent pacemaker implantation is not indicated for
asymptomatic type I second-degree AV block at the
supra-His (AV node) level or that which is not known to
be intra- or infra-Hisian.
I IIa IIb III
Permanent pacemaker implantation is not indicated for
AV block that is expected to resolve and is unlikely to
recur (e.g., drug toxicity, Lyme disease, or transient
increases in vagal tone or during hypoxia in sleep
apnea syndrome in the absence of symptoms).
Chronic Bifascicular Block
I IIa IIb III
Permanent pacemaker implantation is indicated for
advanced second-degree AV block or intermittent
third-degree AV block.
I IIa IIb III
Permanent pacemaker implantation is indicated for
type II second-degree AV block.
I IIa IIb III
Permanent pacemaker implantation is indicated for
alternating bundle-branch block.
Chronic Bifascicular Block (cont’d)
I IIa IIb III
Permanent pacemaker implantation is reasonable for
syncope not demonstrated to be due to AV block when
other likely causes have been excluded, specifically
ventricular tachycardia (VT).
I IIa IIb III
Permanent pacemaker implantation is reasonable for an
incidental finding at electrophysiological study of a
markedly prolonged HV interval (greater than or equal to
100 milliseconds) in asymptomatic patients.
I IIa IIb III
Permanent pacemaker implantation is reasonable for an
incidental finding at electrophysiological study of pacinginduced infra-His block that is not physiological.
Chronic Bifascicular Block (cont’d)
I IIa IIb III
Permanent pacemaker implantation may be considered in
the setting of neuromuscular diseases such as myotonic
muscular dystrophy, Erb dystrophy (limb-girdle muscular
dystrophy), and peroneal muscular atrophy with
bifascicular block or any fascicular block, with or without
symptoms.
I IIa IIb III
Permanent pacemaker implantation is not indicated for
fascicular block without AV block or symptoms.
I IIa IIb III
Permanent pacemaker implantation is not indicated for
fascicular block with first-degree AV block without
symptoms.
Hypersensitive CSS and
Neurocardiogenic Syncope
I IIa IIb III
I IIa IIb III
I IIa IIb III
Permanent pacing is indicated for recurrent syncope
caused by spontaneously occurring carotid sinus
stimulation (CSS) and carotid sinus pressure that
induces ventricular asystole of more than 3 seconds.
Permanent pacing is reasonable for syncope without
clear, provocative events and with a hypersensitive
cardioinhibitory response of 3 seconds or longer.
Permanent pacing may be considered for significantly
symptomatic neurocardiogenic syncope associated
with bradycardia documented spontaneously or at the
time of tilt-table testing.
Hypersensitive CSS and
Neurocardiogenic Syncope (cont’d)
I IIa IIb III
Permanent pacing is not indicated for a hypersensitive
cardioinhibitory response to carotid sinus stimulation
without symptoms or with vague symptoms.
I IIa IIb III
Permanent pacing is not indicated for situational
vasovagal syncope in which avoidance behavior is
effective and preferred.
Knowledge Checkpoint
Name the four most common pacemaker indications.
Knowledge Checkpoint
Permanent pacing is _______________ for situational
vasovagal syncope in which avoidance behavior is effective
and preferred.
Indicated? or Not Indicated?
Knowledge Checkpoint
Permanent pacemaker implantation is ______________
for sinus node dysfunction (SND) with documented
symptomatic bradycardia, including frequent sinus pauses
that produce symptoms.
Indicated? or Not Indicated?
Knowledge Checkpoint
Permanent pacemaker implantation is _____________ for
symptomatic chronotropic incompetence.
Indicated? or Not Indicated?