1. Indications for permanent pace maker implantation
Doc dr Midhat Nurkić FESC
UKC Tuzla
Klinika za kardiovaskularne bolesti
Welcome to Indications and Mode Selection, a course module in CorePace. The Indications and Mode Selection module addresses established and new indications for pacemaker implantation. It also provides guidance in choosing the appropriate mode for optimal pacing therapy.

2. Impulse Formation and Conduction Disturbances
We will start by discussing normal impulse fomation and then move into common conduction disturbances. As abnormal conduction is discussed we will correlate the AHA/ACC guidelines for pacemaker implantation related to that particular rhythm.

3. Normal Heart Function Sinoatrial Node
Initiation of the cardiac cycle normally begins with initiation of the impulse at the sinoatrial (SA) node. A resulting wave of depolarization passes through the right and left atria, which produces the P wave on the surface ECG and stimulates atrial contraction.

4. Atrioventricular Node
Normal Heart Function
Atrioventricular Node
Following activation of the atria, the impulse proceeds to the atrioventricular (AV) node, which is the only normal conduction pathway between the atria and the ventricles. The AV node slows impulse conduction which allows time for contraction of the atria and the pumping of blood from the atria to the ventricles prior to ventricular contraction. Conduction time through the AV node accounts for most of the duration of the PR interval.

5. Normal Heart Function Bundle of HIS
Just below the AV node, the impulse passes through the bundle of His. A small portion of the last part of the PR interval is represented by the conduction time through the bundle of His.

6. Normal Heart Function Left Bundle Branch (LBB)
Posterior Fascicle of LBB
Anterior Fascicle of LBB
After the impulse passes through the bundle of His, it proceeds through the left and right bundle branches. A small portion of the last part of the PR interval is represented by the conduction time through the bundle branches.
Right Bundle Branch (RBB)

7. Normal Heart Function Purkinje Fibers
Next the impulse passes through the Purkinje fibers (interlacing fibers of modified cardiac muscle). A small portion of the last part of the PR interval is represented by the conduction time through the Purkinje system.
Purkinje Fibers

8. Normal Heart Function
The impulse passes quickly through the bundle of His, the left and right bundle branches, and the Purkinje fibers leading to depolarization and contraction of the ventricles. The QRS complex on the ECG represents the depolarization of the ventricular muscle mass.

9. Normal Heart Function
The T wave on the ECG represents the repolarization and relaxation of the ventricles.
Atrial repolarization and relaxation occurs during the QRS complex.

10. Intervals Are Often Expressed in Milliseconds
One millisecond = 1 / 1,000 of a second
Part of understanding timing intervals requires an acquaintance with milliseconds. Many healthcare professionals are accustomed to measuring intervals in seconds. Timing intervals in pacing, however, are always measured in milliseconds. The exception to this is lower and upper rates, which are usually expressed in beats per minute/bpm.
The graphic above shows intervals in milliseconds of a normal sinus beat. The entire graph represents 1000 milliseconds or one second of time.
The smallest box on the ECG represents 40 milliseconds or .04 seconds. The medium box represents 200 milliseconds or .2 seconds.

11. Converting Rates to Intervals and Vice Versa
Rate to interval (ms):
60,000/rate (in bpm) = interval (in milliseconds)
Example: 60,000/100 bpm = 600 milliseconds
Interval to rate (bpm):
60,000/interval ( in milliseconds) = rate (bpm)
Example: 60,000/500 ms = 120 bpm
The way to convert bpm to milliseconds is to divide the rate into 60,000 (the number of milliseconds in one minute). Converting an interval in milliseconds to a rate in bpm is done by dividing 60,000 by the millisecond interval.

12. Normal Sinus Rhythm Atrial rate: 60-100 bpm
PR interval: ms ( seconds)
QRS interval: ms ( seconds)
QT interval: ms ( seconds)

13. Symptoms Syncope or pre-syncope Dizziness Congestive heart failure
Mental confusion
Palpitations
Shortness of breath
Exercise intolerance
Candidates for pacemaker implantation may present with any of the above symptoms or conditions.

14. Sinus Node Dysfunction
Sinus bradycardia
Sinus arrest
SA block
Brady-tachy syndrome
Chronotropic incompetence
Sinus node dysfunction encompasses a variety of impulse formation and conduction problems, including:
sinus bradycardia
sinus arrest
sinoatrial block
supraventricular tachycardias alternating with periods of bradycardia or asystole
chronotropic incompetence
When symptoms are present, the term sick sinus syndrome (SSS) is also used.
Note: As many as 30% of patients will have additional conduction abnormalities elsewhere in the conduction system.

15. Sinus Node Dysfunction – Sinus Bradycardia
Persistent slow rate from the SA node. The parameters from this waveform include:
Rate = 55 bpm
PR interval = 180 ms (.18 seconds)
Sinus bradycardia occurs when the SA node fires at a slow (< 60 bpm) rate.

16. Sinus Node Dysfunction – Sinus Arrest
2.8-second 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 arrest occurs when there is a pause in the rate at which the SA node fires. With sinus arrest there is no relationship between the pause and the basic cycle length.

17. Sinus Node Dysfunction – SA Exit Block
2.1-second pause
Transient blockage of impulses from the SA node
Rate = 52 bpm
PR interval = 180 ms (.18 seconds)
2.1-second pause
SA exit block occurs when the SA node fires, but the impulse does not conduct to the pathways that cause the atrium to contract. In SA exit block there is a relationship between the pattern and the basic cycle length (because the sinus node continues to fire regularly), approximately two, but less commonly three or four times the normal P-P interval.

18. Intermittent episodes of slow and fast rates from the SA node or atria
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
Brady-tachy syndrome occurs when the SA node has alternating periods of firing too slowly (< 60 bpm) and too quickly (> 100 bpm). Brady-tachy syndrome often manifests itself in periods of atrial tachycardia, flutter, or fibrillation. Cessation of the tacycardia is often followed by long pauses from the SA node.

19. Chronotropic Incompetence
Max
Rest
Heart
Rate
Time
Start
Activity
Stop
Quick
Unstable
Slow
It is important to be able to able to increase heart rate with activity (chronotropic competence). The pacemaker and mode selected should provide the ability to increase rate with activity either by “tracking” the sinus node or, if the sinus node is not chronotropically competent, by providing the rate response via a sensor.

20. Pacemaker Indication Classifications
Class I – Conditions for which there is evidence and/or general agreement that permanent pacemakers should be implanted
Class II – Conditions for which permanent pacemakers are frequently used but there is divergence of opinion with respect to the necessity of their insertion
Class IIa: Weight of evidence/opinion is in favor of usefulness/efficacy
Class IIb: Usefulness/efficacy is less well established by evidence/opinion
Class III – Conditions for which there is general agreement that pacemakers are unnecessary
The American College of Cardiology and the American Heart Association have determined guidelines for pacemaker implantation. These 1998 guidelines are divided into three classes. Class II has subcategories A and B.
Gregoratos G, et al. ACC/AHA guidelines for Implantation of cardiac pacemakers and antiarrhythmia devices: a report of the ACC/AHA Task Force on Practice Guidelines (Committee on Pacemaker Implantation). J Am Coll Cardiol :31;
JACC Vol. 31, no. 5 April 1998,

21. Sinus Node Dysfunction – Indications for Pacemaker Implantation
Class I Indications
Sinus node dysfunction with documented symptomatic sinus bradycardia
Symptomatic chronotropic incompetence
Class II Indications
Class IIa: Symptomatic patients with sinus node dysfunction and with no clear association between symptoms and bradycardia
Class IIb: Chronic heart rate < 30 bpm in minimally symptomatic patients while awake
Class III Indications
Asymptomatic sinus node dysfunction
Class I Indication(s):
1. Documented symptomatic sinus bradycardia, including frequent sinus pauses that produce symptoms. May be due to long-term drug therapy of a type and dose for which there is no accepted alternative
2. Symptomatic chronotropic incompetence (of the sinus node)
Class II Indication(s):
1a. Symptomatic patients with sinus node dysfunction and documented rates of < 40 bpm without a clear-cut association between significant symptoms and the bradycardia
1b. In minimally symptomatic patients, chronic heart rate < 30 bpm while awake
Class III Indication(s):
1. Asymptomatic sinus node dysfunction (sinus bradycardia, SA block, or sinus arrest). Also, sinus node dysfunction with symptomatic bradycardia due to nonessential drug therapy
2. Sinus node dysfunction in patients with symptoms suggestive of bradycardia that are clearly documented as not associated with a slow heart rate
Gregoratos G, et al. ACC/AHA guidelines for Implantation of cardiac pacemakers and antiarrhythmia devices: a report of the ACC/AHA Task Force on Practice Guidelines (Committee on Pacemaker Implantation). J Am Coll Cardiol :31;
JACC Vol. 31, no. 5 April 1998,

22. AV Block First-degree AV block Second-degree AV block
Mobitz types I and II
Third-degree AV block
Bifascicular and trifascicular block
AV block can manifest in the following ways listed above.

23. First-Degree AV Block
340 ms
AV conduction is delayed, and the PR interval is prolonged (> 200 ms or .2 seconds)
Rate = 79 bpm
PR interval = 340 ms (.34 seconds)
AV block can be described as a prolongation of the PR interval. The PR interval is the interval from the onset of the P wave to the onset of the QRS complex. First-degree AV block is defined by a PR interval greater than 0.20 seconds (200 msec). First-degree AV block can be thought of as a delay in AV conduction, but each atrial signal is conducted to the ventricles (1:1 ratio).

24. Second-Degree AV Block – Mobitz I (Wenckebach)
ms ms ms
No QRS
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
Second-degree AV block is characterized by intermittent failure of atrial depolarizations to reach the ventricle. There are two patterns of second-degree AV block. The first, Type I, is marked by progressive prolongation of the PR interval in cycles preceding a dropped beat. This is also referred to as Wenckebach or Mobitz Type I block.
The AV node is most commonly the site of Mobitz I block. The QRS duration is usually normal.

25. Second-Degree AV Block – Mobitz II
P P QRS
Regularly dropped ventricular beats
2:1 block (2 P waves to 1 QRS complex)
Ventricular rate = 60 bpm
Atrial rate = 110 bpm
Mobitz Type II second-degree AV block refers to intermittent dropped beats preceded by constant PR intervals. To differentiate Mobitz I from Mobitz II, note the PR interval in the beats preceding and following the dropped beat. If a difference between these two PR intervals is more than 0.02 seconds (20 msec), then it is Mobitz I. If the difference is less than 0.02 seconds, then it is Mobitz II.
The infranodal (His bundle) tissue is most commonly the site of Mobitz II block.
Note: Advanced second-degree block refers to the block of two or more consecutive P waves (i.e., 3:1 block).

26. Third-Degree AV Block
No impulse conduction from the atria to the ventricles
Ventricular rate = 37 bpm
Atrial rate = 130 bpm
PR interval = variable
Third-degree AV block is also referred to as complete heart block. It is characterized by a complete dissociation between P waves and QRS complexes. The QRS complexes are not caused by conduction of the P waves through the AV node to the ventricles, but rather the QRS is initiated at a site below the AV node (such as in the His bundle or the Purkinje fibers). This “escape rhythm” is normally 40–60 bpm if initiated by the His bundle (a junctional rhythm) and <40 bpm if initiated by the Purkinje fibers.

27. AV Block – Indications Class I Indications
3rd degree AV block associated with:
Symptomatic bradycardia (including those from arrhythmias and other medical conditions)
Documented periods of asystole > 3 seconds
Escape rate < 40 bpm in awake, symptom free patients
Post AV junction ablation
Post-operative AV block not expected to resolve
Second degree AV block regardless of type or site of block, with associated symptomatic bradycardia
Class I Indication(s):
In addition to those listed, other indications for 3rd degree block include:
Neuromuscular diseases with AV block such as myotonic muscular dystrophy, Kearns-Sayre syndrome, Erb’s dystrophy, and peroneal muscular atrophy.
Gregoratos G, et al. ACC/AHA guidelines for Implantation of cardiac pacemakers and antiarrhythmia devices: a report of the ACC/AHA Task Force on Practice Guidelines (Committee on Pacemaker Implantation). J Am Coll Cardiol :31;
JACC Vol. 31, no. 5 April 1998,

28. AV Block – Indications Class II Indications Class IIa:
Asymptomatic CHB with a ventricular rate > 40 bpm
Asymptomatic Type II 2nd degree AV block
Asymptomatic Type I 2nd degree AV block within the His-Purkinje system found incidentally at EP study
First-degree AV block with symptoms suggestive of pacemaker syndrome and documented alleviation of symptoms with temporary AV pacing
Class IIb:
First degree AV block > 300 ms in patients with LV dysfunction in whom a shorter AV interval results in hemodynamic improvement
In addition to those listed, other indications include:
Class II Indication(s):
IIa: Asymptomatic Type II 2° AV block. If not paced, asymptomatic Type II 2° AV block patients should be followed very closely because Type II 2° AV block patients with symptoms are at a high risk for developing CHB. Most patients with type II block are symptomatic, which is a Class I indication. True asymptomatic Type II block is rare and pacemaker therapy is generally recommended.
IIb: Marked first-degree AV block in patients with LV dysfunction and symptoms of congestive heart failure in whom a shorter AV interval results in hemodynamic improvement, presumably by decreasing left atrial filling pressure.
Gregoratos G, et al. ACC/AHA guidelines for Implantation of cardiac pacemakers and antiarrhythmia devices: a report of the ACC/AHA Task Force on Practice Guidelines (Committee on Pacemaker Implantation). J Am Coll Cardiol :31;
JACC Vol. 31, no. 5 April 1998,

29. AV Block – Indications Class III Indications
Asymptomatic 1st degree AV block
Asymptomatic Type I 2nd degree AV block at supra-His level
AV block expected to resolve and unlikely to recur (e.g., drug toxicity, Lyme Disease)
Gregoratos G, et al. ACC/AHA guidelines for Implantation of cardiac pacemakers and antiarrhythmia devices: a report of the ACC/AHA Task Force on Practice Guidelines (Committee on Pacemaker Implantation). J Am Coll Cardiol :31;
JACC Vol. 31, no. 5 April 1998,

30. Right bundle branch block and left posterior hemiblock
Bifascicular Block
Right bundle branch block and left posterior hemiblock
Bifascicular block is defined as one of the following:
Right bundle branch block and left posterior hemiblock (highlighted in red)
Right bundle branch block and left anterior hemiblock
Complete left bundle branch block
Bifascicular block is marked by prolonged QRS (> 120 ms or .12 seconds or longer).

31. Right bundle branch block and left anterior hemiblock
Bifascicular Block
Right bundle branch block and left anterior hemiblock
Bifascicular block
Right bundle branch block and left anterior hemiblock (highlighted in red and yellow)

32. Complete left bundle branch block
Bifascicular Block
Bifascicular block
Complete left bundle branch block (highlighted red)
Complete left bundle branch block

33. Trifascicular Block
Complete block in the right bundle branch and complete or incomplete block in both divisions of the left bundle branch
Trifascicular Block has the appearance of AV nodal block. Combinations that constitute trifascicular block are:
Right bundle branch block, complete left anterior fascicular block and complete left posterior fascicular block.
Combination of complete block in one or two subdivisions of the common bundle and incomplete block in one or two subdivisions.

34. Bifascicular and Trifascicular Block (Chronic) – Indications
Class I Indications
Intermittent 3rd degree AV block
Type II 2nd degree AV block
Class II Indications
Class IIa:
Syncope not proved to be due to AV block when other causes have been exluded, specifically VT
Prolonged HV interval ( >100 ms)
Pacing-induced infra-His block that is not physiological
Class IIb: None
Class III Indications
Asymptomatic fascicular block without AV block
Asymptomatic fascicular block with 1st degree AV block
Symptomatic advanced AV block that develops in patients with underlying bifascicular and trifascicular block is associated with a high mortality rate and a significant incidence of sudden death, though there is evidence of a slow rate of progression to 3rd degree AV block.
Syncope is common in patients with bifascicular block, and evidence proves an increased incidence of sudden cardiac death. Therefore, if the cause of syncope in the presence of bi/trifascicular block cannot be determined, prophylactic pacing is indicated.
PR and HV intervals have been identified as possible predictors of 3rd degree AV block and sudden death in the presence of underlying bifascicular block. However, the prolongation is often at the level of the AV node, and frequently there is no correlation between the PR and HV intervals and progression to 3rd degree AV block and the incidence of sudden cardiac death.
Gregoratos G, et al. ACC/AHA guidelines for Implantation of cardiac pacemakers and antiarrhythmia devices: a report of the ACC/AHA Task Force on Practice Guidelines (Committee on Pacemaker Implantation). J Am Coll Cardiol :31;
JACC Vol. 31, no. 5 April 1998,

35. Neurocardiogenic Syncope
Carotid Sinus Syndrome (CSS)
Vasovagal Syncope (VVS)
The two most common manifestations of neurocardiogenic syncope are CSS and VVS. While the role of pacing in CSS is fairly well established, the role pacing plays in VVS is subject to more debate.

36. 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
Other activities that stimulate the carotid sinus
Hypersensitive Carotid Sinus Syndrome (CSS) is a disease of the carotid sinus, a dilated portion of the carotid artery that has pressure-sensitive receptors that regulate heart rate and blood pressure. CSS is an extreme reflex response to carotid sinus stimulation and usually results in bradycardia and/or vasodilation. It can be induced by, among other things, a tight collar, shaving, head turning, exercise, and, of course, carotid sinus massage.

37. Mechanisms of Neurocardiogenic Syncope
Cardioinhibitory
Initiated by inappropriate drop in heart rate
Vasodepressor
Symptomatic decrease in systolic blood pressure due to vasodilation
Mixed
Includes components of cardioinhibitory and vasodepressor
Neurocardiogenic syncope can be classified by the dominant syncopal mechanism:
Cardioinhibitory- When syncope is primarily due to an inappropriate drop in heart rate, pacing intervention may be effective.
Vasodepressor- When syncope is primarily due to dialtion of the capillary bed, with resulting blood pooling. Pacing is probably ineffective in these patients.
Mixed- Significant cardioinhibition and vasodepression both occur.
Both CSS and VVS occur in all forms, although cardioinhibitory syncope occurs more commonly in CSS than VVS.

38. Vasovagal Syncope (VVS)
Neurally mediated transient loss of consciousness
Can be precipitated by:
Fear, anxiety
Physical pain or anticipation of trauma/pain
Prolonged standing
Symptoms include:
Dizziness
Blurred vision
Weakness
Nausea, abdominal discomfort
Sweating
Vasovagal syncope is a neurally mediated transient loss of consciousness and can be triggered by prolonged standing, fear, mental anguish, physical pain or anticipation of trauma or pain. The most common symptoms are dizziness, blurred vision, weakness, nausea, sweating, and abdominal discomfort.

39. CSS and VVS – Indications
Class I Indications
Recurrent syncope caused by carotid sinus stimulation; minimal carotid sinus pressure induces a period of asystole > 3 seconds in duration (CSS)
Gregoratos G, et al. ACC/AHA guidelines for Implantation of cardiac pacemakers and antiarrhythmia devices: a report of the ACC/AHA Task Force on Practice Guidelines (Committee on Pacemaker Implantation). J Am Coll Cardiol :31;
JACC Vol. 31, no. 5 April 1998,

40. CSS and VVS – Indications
Class II Indications
Class IIa:
Recurrent syncope without clear, provocative events and with a hypersensitive cardioinhibitory response
Syncope of unexplained origin when major abnormalities of sinus node function or AV conduction are discovered or provoked in EP studies
Class IIb:
Neurally mediated syncope with significant bradycardia reproduced by a head-up tilt table testing (VVS)
Tilt table testing is a diagnostic procedure which includes a tilt table elevated to a 60-90o angle with the patient’s head up. Substantial bradycardia (less than 40 bpm for a certain duration) asystole of > 3 seconds, or blood pressure falling enough to cause syncope indicate a positive test.
Gregoratos G, et al. ACC/AHA guidelines for Implantation of cardiac pacemakers and antiarrhythmia devices: a report of the ACC/AHA Task Force on Practice Guidelines (Committee on Pacemaker Implantation). J Am Coll Cardiol :31;
JACC Vol. 31, no. 5 April 1998,

41. CSS and VVS – Indications
Class III Indications
Asymptomatic with a positive response to carotid sinus massage (CSS)
Recurrent syncope, lightheadedness, or dizziness without a cardioinhibitory response (CSS/VVS)
Situational vasovagal syncope in which avoidance behavior is effective
Vague symptoms such as dizziness, light-eadedness, or both, with hyperactive cardioinhibitory response to CS stimulation
Gregoratos G, et al. ACC/AHA guidelines for Implantation of cardiac pacemakers and antiarrhythmia devices: a report of the ACC/AHA Task Force on Practice Guidelines (Committee on Pacemaker Implantation). J Am Coll Cardiol :31;
JACC Vol. 31, no. 5 April 1998,

42. Other Indications

43. Pacing After Cardiac Transplantation
Class I Indications
Symptomatic bradyarrhythmias/chronotropic incompetence not expected to resolve and meets other Class I indications for permanent pacing
Class IIa: None
Class IIb: Symptomatic bradyarrhythmias/chronotropic incompetence that, although transient, may persist for months and require intervention
Asymptomatic bradyarrhythmias
Class II Indications
Bradyarrhythmias after cardiac transplantation are common, occurring in 8%-23% of patients with transplantation and are usually associated with sinus node dysfunction. Approximately 50% of these patients demonstrate significant improvement within 6 to 12 months after transplantation, therefore, long term pacing is often unnecessary. However, patients with irreversible sinus node dysfunction or AV block with previously stated Class I Indications should have permanent pacing.
Gregoratos G, et al. ACC/AHA guidelines for Implantation of cardiac pacemakers and antiarrhythmia devices: a report of the ACC/AHA Task Force on Practice Guidelines (Committee on Pacemaker Implantation). J Am Coll Cardiol :31;
Class III Indications
JACC Vol. 31, no. 5 April 1998,

44. AV Block Associated with Myocardial Infarction – Indications
Class I Indications
Persistent and symptomatic 2nd or 3rd degree AV block
Persistent Type 2nd degree AV block in the His-Purkinje system with bilateral BBB or 3rd degree AV block within or below the His-Purkinje system
Transient advanced 2nd or 3rd degree infranodal AV block and associated bundle branch block
Class IIa: None
Class IIb: Persistent 2nd or 3rd degree AV block at the AV node level
Transient AV block in absence of intraventricular conduction defect
Pre-existing 1st degree AV block with bundle branch block
Class II Indications
Class III Indications also include:
Transient AV block in presence of isolated left anterior fasicular block (LAFB).
Acquired LAFB in absence of AV block.
The long-term prognosis of survivors of acute myocardial infarction who develop AV block is related primarily to the extent of myocardial damage and the character of intraventricular conduction disturbances rather than AV block itself, and do not necessarily depend on the presence of symptoms.
This list should also not be confused with the indications for temporary pacing in the post-myocardial infarction setting.
Gregoratos G, et al. ACC/AHA guidelines for Implantation of cardiac pacemakers and antiarrhythmia devices: a report of the ACC/AHA Task Force on Practice Guidelines (Committee on Pacemaker Implantation). J Am Coll Cardiol :31;
Class III Indications
JACC Vol. 31, no. 5 April 1998,

45. Summary of Pacemaker Indications
Sinus node dysfunction
AV block
Bifascicular and trifascicular block
Hypersensitive Carotid Sinus Syndrome (CSS)
Vasovagal Syncope (VVS)
Pacing after cardiac transplantation
AV block associated with myocardial infarction