Bradycardia, pacing
Bradycardia is defined as any rhythm
disorder with a heart rate less than 60
beats per minute. (Typically it will be
<50/min)
Bradycardia can be a normal nonemergent
rhythm. For instance, well
trained athletes may have a normal heart
rate that is less than 60 bpm.
Symptomatic bradycardia
Symptomatic bradycardia exists when the
following 3 criteria are present:
1.) The heart rate is slow;
2.) The patient has symptoms;
3.) The symptoms are due to the slow heart
rate.
Symptoms
Syncope
Dizziness
Congestive heart failure
Mental confusion
Palpitations
Shortness of breath
Exercise intolerance
Causes of Conduction Defects
Coronary Artery Disease
Idiopathic Degeneration
Calcification
Endocarditis
Heart Surgery
RF Ablation
Diagnosis
Electrocardiogram (ECG)
Exercise ECG or stress test
Holter monitor (24 to 72 hour ECG)
Tilt table test
Electrophysiology (EP) study:
External loop recorder
Insertable loop recorder
BUDOUCNOST - MONITORY
Insertable Reveal XT
Injectable Reveal
Objemově 1/9
Životnost 3 roky
MRI kompatibilní
Sinus Node Dysfunction
Sinus bradycardia
Sinus arrest
SA block
Brady-tachy
syndrome
Chronotropic
incompetence
Sinus bradycardia--etiologies
often seen as a normal variation in athletes,
during sleep, or in response to a vagal
maneuver. If the bradycardia becomes slower
than the SA node pacemaker, a junctional
rhythm may occur.
15-25% Acute MI, esp. affecting inferior wall
Hypothyroidism, infiltrative diseases
(sarcoid, amyloid, hyperkalemia)
Drugs: beta-blockers, digitalis, calcium channel
blockers, amiodarone, cimetidine, lithium
Digoxin Effect
Sinus Node Dysfunction –
Sinus Arrest
Failure of sinus node discharge resulting in the
absence of atrial depolarization and periods of
ventricular asystole
– Rate = 75 bpm
– PR interval = 180 ms (.18 seconds)
2.8-second arrest
Sinus Node Dysfunction –
Bradycardia-Tachycardia (Brady-Tachy)
Syndrome
Intermittent episodes of slow and fast
rates from the SA node or atria
– Rate during bradycardia = 43 bpm
– Rate during tachycardia = 130 bpm
Chronotropic Incompetence
Max
Rest
Heart
Rate
Time
Start
Activity
Stop
Activity
Quick
Unstable
Slow
Sick Sinus Syndrome--etiology
Often due to sinus node fibrosis, SNode arterial
atherosclerosis, inflammation (Rheumatic fever,
amyloid, sarcoid)
Occurs in congenital and acquired heart disease
and after surgery
Hypothyroidism, hypothermia
Drugs: digitalis, lithium, cimetidine, methyldopa,
reserpine, clonidine, amiodarone
Most patients are elderly, may or may not have
symptoms
AV Block
First-degree AV
block
Second-degree AV
block
– Mobitz types I and II
Third-degree AV
block
Bifascicular and
trifascicular block
First-Degree AV Block
AV conduction is delayed, and the PR
interval is prolonged (> 200 ms or .2
seconds)
– Rate = 79 bpm
– PR interval = 340 ms (.34 seconds)
340 ms
Second-Degree AV Block –
Mobitz I (Wenckebach)
Progressive prolongation of the PR interval until
a ventricular beat is dropped
– Ventricular rate = irregular
– Atrial rate = 90 bpm
– PR interval = progressively longer until a P-wave fails
to conduct
200 360 400
ms ms ms
No
QRS
Second-Degree AV
Block – Mobitz II
Regularly dropped ventricular beats
– 2:1 block (2 P waves to 1 QRS complex)
– Ventricular rate = 60 bpm
– Atrial rate = 110 bpm
P P QRS
2nd degree block Type II (Mobitz 2)
Normal PR intervals with sudden failure of a p wave to
conduct
Usually below AV node and accompanied by BBB or
fascicular block
Often causes pre/syncope; exercise worsens sxs
Generally need pacing, possibly urgently if symptomatic
Third-Degree AV Block
No impulse conduction from the atria to the
ventricles
– Ventricular rate = 37 bpm
– Atrial rate = 130 bpm
– PR interval = variable
3rd Degree AV Block
Complete AV disassociation, HR is a ventricular rate
Will often cause dizziness, syncope, angina, heart failure
Can degenerate to Vtach and Vfib
Will need pacing, urgent referral
Hypersensitive Carotid Sinus
Syndrome (CSS)
Extreme reflex response to carotid sinus
stimulation
Results in bradycardia and/or vasodilation
Can be induced by:
– Tight collar
– Shaving
– Head turning
– Exercise
Bradycardia Pharmacology
Atropine: The first drug of choice for
symptomatic bradycardia.
Dopamine: Second-line drug for
symptomatic bradycardia when atropine is
not effective.
Epinephrine: Can be used as an equal
alternative to dopamine when atropine is
not effective.
Pacemakers
Pacemakers are the electronic devices
that can be used to initiate
the heartbeat when the heart´s
intrinsic electrical system cannot
effectively generate a rate adequate
to support cardiac output
Pacemaker history
First pacemaker implanted in 1958
First ICD implanted in 1980
Greater than 500,000 patients in the US
population have pacemakers
115,000 implanted each year
Types of Pacemaker
Temporary pacemaker
Permanent pacemaker
Indications for a temporary
pacemaker
Acute myocardial infarction with:
– Asystole.
– Symptomatic bradycardia with hypotension
not responsive to atropine).
– Bilateral bundle branch block (BBB)
(alternating BBB or right bundle branch block
(RBBB) with alternating left anterior hemiblock
(LAHB)/left posterior hemiblock (LPHB)).
Indications for a temporary
pacemaker
Acute myocardial infarction with:
– New or indeterminate age bifascicular block
with first-degree AV block.
– Mobitz type II second-degree AV block.
– A pacemaker is only indicated in an inferior
myocardial infarction if these conduction
disturbances are present.
Indications for a temporary
pacemaker
Bradycardia not associated with acute
myocardial infarction:
– Asystole.
– Second-degree or third-degree AV block with
haemodynamic compromise or syncope at
rest.
– Ventricular tachyarrhythmias secondary to
bradycardia.
Indications for a temporary
pacemaker
Suppression of drug-resistant ventricular
tachyarrhythmia or supraventricular
tachycardia.
Drug overdose, eg digoxin, betablockers,
verapamil.
Indications for Pacing
Symptomatology
+ Documented Events
Reliable Indications for
Pacing
Causes of Conduction Defects
Coronary Artery Disease
Idiopathic Degeneration
Calcification
Endocarditis
Heart Surgery
RF Ablation
Summary of Pacemaker Indications
Sinus node dysfunction
AV block
Bifascicular and trifascicular block
Hypersensitive Carotid Sinus Syndrome
(CSS)
Vasovagal Syncope (VVS)
Transvenous Access
Internal Jugular
External Jugular
Subclavian
Axillary
Cephalic
elektrody
Epicardiální
Endocardiální
Kardiostimulátor, CRT - P
Implantace síňové elektrody
Komorová elektroda
Pacemaker Coding
The NASPE/BPEG code …
– First letter indicates the chamber being paced :
A for Atrium, V for Ventricle, D for Double, O for none
… VVI : pacing in the ventricle
… AAI : pacing in the atrium
… DDD : pacing in both chambers
Pacemaker Coding
The NASPE/BPEG code …
– Second letter indicates the chamber being
sensed :
A for Atrium, V for Ventricle, D for double, O for none
… VVI : sensing in the ventricle
… AAI : sensing in the atrium
… DDD : sensing in both chambers
Pacemaker Coding
The NASPE/BPEG code …
– Third letter indicates the reaction to sensing :
I = Inhibited, T = Triggered, D = Double, O = none
e.g. VVT :
A pacing pulse is emitted simultaneously with
any detection, as in VVI pacing will also occur if no
activity is detected during the lower rate interval
… before : avoid ‘standstill’ during interference
today : mainly a diagnostic mode
Providing Optimal Pacing
Therapy
Heart rate increase
Stroke volume maximization
Atrial based pacing
Normal ventricular activation sequence
Mode Selection Decision Tree
DDIR with
SV PVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
Determining the Optimal Pacing
Mode: Mrs. Peacock
Patient information:
– Documented symptomatic sinus bradycardia
– When exercise tested, rate does not increase appropriately with
increasing work loads
– At present, AV conduction is intact
Is AV conduction
intact?
Mode Selection Decision Tree:
Mrs. Peacock
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
Mode Selection Decision Tree:
Mrs. Peacock
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
Mode Selection Decision Tree:
Mrs. Peacock
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
Determining the Optimal Pacing
Mode: Professor Plum
Patient information:
– Professor Plum has intermittent 2nd degree Type II AV block
with symptoms
– Professor Plum’s atrial rate responded appropriately to an
exercise test
P P QRS
Mode Selection Decision Tree:
Prof. Plum
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
Is SA node function
presently adequate?
Mode Selection Decision Tree:
Prof. Plum
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
Mode Selection Decision Tree:
Prof. Plum
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
Determining the Optimal Pacing
Mode: Colonel Mustard
Patient information:
– Colonel Mustard has complete heart block and intermittent atrial
flutter
– Colonel Mustard’s heart rate does not reach 100 bpm in
response to an exercise stress test
Mode Selection Decision Tree:
Colonel Mustard
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
Mode Selection Decision Tree:
Colonel Mustard
Mode Selection Decision Tree:
Colonel Mustard
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
Determining the Optimal Pacing Mode: Mr.
Green
Patient information:
– Mr. Green has brady-tachy syndrome with intact AV conduction
– Mr. Green’s heart rate does not reach 100 bpm in response to an
exercise stress test
Mode Selection Decision Tree:
Mr. Green
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
Mode Selection Decision Tree:
Mr. Green
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
Mode Selection Decision Tree:
Mr. Green
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
Determining the Optimal Pacing
Mode: Mrs. White
Patient information:
– Mrs. White has chronic atrial fibrillation with an irregular
ventricular rate
– Mrs. White’s heart rate does not reach 100 bpm in response to
an exercise stress test
Mode Selection Decision Tree:
Mrs. White1
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
1Hypothetical patient example
Mode Selection Decision Tree:
Mrs. White1
DDIR with
SVPVARP
DDDR with
MS
N
VVI
VVIR
Are they
chronic?
Y
Y N
DDD, VDD
DDDR DDDR
Y N
Is AV conduction
intact?
Is SA node function
presently adequate?
Symptomatic
bradycardia
Are atrial
tachyarrhythmias
present?
Is SA node function
presently adequate?
Is AV conduction
intact?
Y
Y N
AAIR
DDDR
DDD, DDI
with RDR
N N(SSS)
(CSS,
VVS)
N
1Hypothetical patient example