BRADYCARDIAFor CATH LAB STAFF

台大醫院雲林分院陳建鈞

BRADYCARDIA • HEART RATE < 50 bpm

• High variability of human heart rate

• Infant • Athelet

Evaluation of bradycardia • ECG • RATE • RHYTHM • P, atrial rhythm, QRS, pattern, Knowledge

• Clinical symtpoms/signs • Low cardiac output

• Dizziness, near syncope, syncope, ischaemic chest pain, and hypoxic seizures

• Sudden death risk

• Drug, medical condition (thyroid…)

•

Management of bradycardia • ACLS !!

• Avoid offending drug • (beta-blocker, CCB, digoxin, AAD)

• Drug increase heart rate • IV Dopamine, isoproterenol, atropine…• Aminophylline, beta-agonist

• Permanent pacemaker !

Cardiac Arrhythmia

• Normal sinus rhythm• HR: 60 - 100 / min

• Bradyarrhythmia

• sinus bradycardia, sick sinus syndrome

• AV block, A fib. with SVR

• Hypersensitive carotid sinus syndrome

• Sinus node is supplied by the RCA in 60% of people and by the LCX in 40%.

• AV node is supplied by the RCA in 90% and by the LCX in 10% of patients.

• Right bundle supplied by LAD

• Left bundle supplied by branches of the RCA and LADZimetbaum PJ, Josephson ME. NEJM, 2003

Taken from www.baptistoneword.org

Conduction System Anatomy

Sinus Nodal Dysfunction

• Definition• Rate / Duration• Physical conditioning• Chronotropic incompetence (max HR <100/min)

• Etiology (intrinsic vs. extrinsic)• Degeneration• Ischemia• Drug / Electrolyte• Surgery / Transplantation• Family history• Neurocardiogenic

Evaluation of Sinus Nodal Dysfunction

• History / Physical examination

• Thyroid function / electrolyte

• ECG

• UCG

• Holter ECG / Loop event recorder

• Treadmill testing

• EP study

SA Block

2nd degree SA exit block type I

HR: 91bpm, PR:142bpm

2nd degree SA exit block type II

Sick Sinus Syndrome vs. Syncope

Tachycardia-Bradycardia Syndrome

EP Study in Sinus Nodal Dysfunction

• Sinus nodal recovery time• cSRT < 550 ms• SRT/NSR < 150%• Total recovery time < 5 sec

• Sinoatrial conduction time• 45 to 125 ms

• Sinus nodae electorgram• SACT: 60-110 ms• Depolarization duration < 200 ms

Sinus Nodal Recovery Time

Sinoatrial Conduction Time

Limitation of EPS in Sinus Nodal Dysfunction

• Autonomic nerve modulation• Vagal dominant• Intrinsic heart rate (107-0.53x age)• Total autonomic blockade (Atropine/Esmolol)

• More specific, less sensitive• Sensitivity: 54% (35-93%)• Specificity: 88% (combined with SACT)

• Other issue:• Secondary pause: SA exit block• Pacing rate and duration• SA entrance block

Definition of AV Block• First-degree: PR interval > 0.2 sec• Second-degree:

• Mobitz type I (Wenchebach): inconstant PR interval • Progressive increase in PR interval• RR interval may progressively decrease• Grouping of QRS

• Mobitz type II: constant PR interval before and after single block beat• Advanced: 2:1; 3:1; 4:1… AV block

• Third-degree (complete): AV dissociation

[PACE 1993; 16: 1221-1226]

Causes of Cardiac Conduction Disturbances

• Ischemic heart disease• Infectious and inflammatory heart disease• Infiltrative heart disease• Degenerative processes• Congenital• Surgical, RFCA and alcohol septal ablation • Drug and toxin• Electrolyte disturbances• Neuromyopathic disorders (HLA-B27)

AV block

2nd degree AV block

1. Identify the mechanism

2nd degree Mobitz type I AV block(Wenckebach phenomenon)

HR: 44bpm, PR: 292ms

2:1 AV block

HR: 41bpm, PR: 192ms

Three degree (Complete) AV blockHR: 43bpm

HR: 45bpm

Complete AV block

AV block vs. Syncope

Atrial Fibrillation with slow ventricular rate

Escape rhythm

• When the ventricles are not stimulated as a result of automaticity or conduction problems

• Marked sinus bradycardia, sinus pause, complete AV block

• Junctional vs. ventricular escape rhythm• Junctional: narrow, rate: 40~60bpm•Ventricular: wide, rate: 20~40bpm

Sinus bradycardia with junctional escape rhythmHR: 50bpm

Complete AV block with ventricular escape rhythmHR: 27bpm

AV BlockComplete in presence of A Fib

EP Study in AV Conduction Disturbances

• Key point• QRS width, site of block• Escape rate• Syncope

• His electrogram• AH block; Intra-His block; HV block• HV time: < 55 ms

• Stress test• Incremental atrial pacing• After ventricular pacing• pharmacological test

2.Identify Etiology

2.Identify Etiology

Bundle Branch Block

Classification of Trifascicular Block

• AV 1:1 conduction• Alternating RBBB and LBBB• Fixed RBBB with alternating LAH and LPH block• RBBB + prolonged HV interval• LBBB + prolonged HV interval

• During second- or third-degree AV block• Permanent trifasicular block: complete AV block• Permanent bifasicular block

• RBBB with alternating LAH and LPH block• Alternating RBBB and LBBB

[PACE 1993; 16: 1221-1226]

Alternation Bundle Branch Block

Thank You….

ACC/AHA Guidelinesfor Pacemaker and ICD Implant

• Level of Evidence (Cardiology)A. data derived from multicenter randomized

trials

B. data from limited or non-randomized studiesor observational studies

C. expert consensus but no formal studies

Gregoratos, Circ 1998; 97: 1325-1335

Symptomatology +Documented Events

ECG documentation in the medical record is essential !

Reliable Indicationsfor Pacing

=

Indications For Pacing

• Sick Sinus Syndrome• Heart Block• Carotid Sinus Hypersensitivity

and Neurocardiogenic Syncope• HOCM, DCM

Indications For Pacing

• Sinus Bradycardia • Sinus Arrest• SA Exit Block• Bradycardia-

Tachycardia Syndrome• Symptomatic

chronotropic incompetence

Sinus Node Dysfunction (Sick Sinus Syndrome)

Class I Indications:Pacing in Sinus Node Dysfunction

1. Symptomatic bradycardia or frequent symptomatic sinus pauses (Level of Evidence: C)

2. Symptomatic chronotropic incompetence (Level of Evidence: C)

3. Symptomatic bradycardia that results from required drug therapy (Level of Evidence: C)

Max

Rest

HeartRate

Time

StartActivity

StopActivity

Quick

Unstable

Slow

Chronotropic Incompetence1. Identify the mechanism

Class IIa Indications: Pacing in Sinus Node Dysfunction

1. SN dysfunction occurring spontaneously or as a result of necessary drug therapy, with HR <40 bpm, when a clear association between significant symptoms consistent with bradycardia and the actual presence of bradycardia has not been documented (Level of Evidence: C)

2. Syncope of unknown etiology when SN dysfunction is provoked or discovered during EP testing that is thought to be clinically significnat (Level of Evidence: C)

Class IIb & III Indications: Pacing in Sinus Node Dysfunction

Class IIb

2. In minimally symptomatic patients, chronic heart rates <40 bpm, while awake.

Class III

3. SN dysfunction in asymptomatic patients(Level of Evidence: C)

2. SN dysfunction in patients with symptoms that are clearly documented in the absence of bradycardia (Level of Evidence: C)

3. SN dysfunction with symptomatic bradycardia due to nonessential drug therapy.

Pacing In Acquired AV Block

Class I Indications: Pacing for Acquired AV Block

1. Third-degree or advanced second-degree AV block at any anatomic level with:

a) Symptoms (including heart failure) attributable to AV block (C)

b) Arrhythmias and other medical conditions that require drugs that result in symptomatic bradycardia (C)

c) Documented asystole 3.0sec. any escape rate <40 bpm, or any escape rhythm below the AV junction in awake, asymptom-free patients (C)

d) A documented asystole >5 sec in awake, asymptomatic patients in atrial fibrillation (C)

e) After catheter ablation of the AV junction (C)f) Postoperative AV block not expected to resolve after

cardiac surgery (C)g) Neuromuscular diseases with AV block, with or without

symptoms of bradycardia (B)

Class I Indications:Pacing for Acquired AV Block

2.Asymptomatic third-degree AV block at any anatomic site with an average awake ventricular rate >40bpm in patients with cardiomegaly or LV dysfunction (C)

3.Second-degree or third-degree AV block during exercise in the absence of myocardial ischemia (C)

4.Symptomatic second-degree AV block regardless of type or site of block (B)

Class IIa Indications: Pacing for Acquired AV Block

1. Advanced second-degree or third-degree AV block at any anatomic site with an average ventricular rate >40bpm in the absence of cardiomegaly (C)

2. Asymptomatic type second-degree AV block at intra- or infra-His levels found at EP study (B)

3. First- or second-degree AV block with symptoms similar to those of "pacemaker syndrome“(B)

4. 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 RBBB, pacing becomes a class I recommendation (B)

Class IIb Indications: Pacing for Acquired AV Block

1.AV block due to drug use or toxicity when the block is expected to recur even after withdrawal of the drug (B)

2.Neuromuscular diseases with any degree of AV block (including first degree AV block), with or without symptoms (B)

Class III Indications: Pacing for Acquired AV Block

1.Asymptomatic first-degree AV block (B)

2.Asymptomatic type I second-degree AV block at a site above the His level or not known by EP study (B)

3.AV block expected to resolve and unlikely to recur (e.g., drug toxicity, Lyme disease, etc), or during hypoxia in sleep apnea syndrome in absence of symptoms (B)

Pacing for Chronic Bifascicular and Trifascicular Block

-risk of sudden death or progression to complete heart block

Class I Indications: Pacing in Chronic Bifasicular and

Trifasicular Block

1. Intermittent third-degree or advanced second-degree AV block (B)

2.Type II second-degree AV block (B)

3.Alternating bundle-branch block (C)

Class IIa Indications: Pacing in Chronic Bifasicular and

Trifasicular Block

1. Syncope not demonstrated to be due to AV block when other likely causes, specifically ventricular tachycardia, have been excluded (B)

2. Incidental finding at EP study of markedly prolonged HV interval (≧ 100 ms) in asymptomatic patients (B)

3. Incidental finding at EP study of pacing-induced infra-His block that is not physiological (B)

Class IIb & III Indications: Pacing in Chronic Bifasicular and

Trifasicular Block

Class IIa1. Neuromuscular diseases…with any

degree of fascicular block, with or without symptoms (C)

Class III2. Fascicular block without AV block or

symptoms (B)

2. Fascicular block with first-degree AV block without symptoms (B)

Pacing In congenital AV block• Without congenital heart disease

• Symptomatic• Wide QRS escape rhythm

• EP test: Infra-Hisian block• <55 bpm in infants; • <50bpm with long pause (2~3X BCL)

• Special consideration in Congenital heart disease• Post-op• HF<70bpm in infants; • <40bpm or pause >3sec

Pacing in Neurocardiogenic Syncope

Pacing in Neurally Mediated Reflex Syncope

Class I

Recurrent syncope caused by carotid sinus hypersensitivity, defined as minimal carotid sinus pressure inducing ventricular asystole of >3 seconds in patients not receiving medications that depress the sinus node or AV conduction (Level of Evidence: C)

Class IIa

Syncope in the absence of definite provocative event with a pause of ≥3 seconds with carotid massage (Level of Evidence: C)

Class IIb

Recurrent symptomatic neurocardiogenic syncope with a cardioinhibitory response during tilt-table testing (Level of Evidence: B)

Class III

A cardioinhibitory response during carotid sinus stimulation without symptoms or with vague symptoms (Level of Evidence: C)Situational vasovagal syncope in which avoidance behavior is effective (Level of Evidence: C)

Head-Up Tilt Table Testing

• Protocol• Fast > 2 hours• continuous ECG and

blood pressure mornitering

• Tilt to 60~80°• 20~45 minutes

2.Identify Etiology

Head-Up Tilt Test (HUT)2.Identify Etiology

NBG Code Review

IChamber

Paced

IIChamber

Sensed

IIIResponseto Sensing

IVProgrammableFunctions/Rate

Modulation

VAntitachy

Function(s)

V: Ventricle V: Ventricle T: Triggered P: Simpleprogrammable

P: Pace

A: Atrium A: Atrium I: Inhibited M: Multi-programmable

S: Shock

D: Dual (A+V) D: Dual (A+V) D: Dual (T+I) C: Communicating D: Dual (P+S)

O: None O: None O: None R: Rate modulating O: None

S: Single (A or V)

S: Single (A or V)

O: None

3.Identify Treatment

Pacing Mode SelectionFactor to consider when choosing pacing mode• Underlying rhythm disturbance• Overall physical condition• Associated medical condition• Exercise capacity• Chronotropic response to exercise• Effect of pacing mode on long-term morbidity and

mortality

Pacing mode selection• DDD/AAI (atrial based pacing) vs. VVI (ventricular

based pacing)

• lower mortality• lower Af incidence

• ACC/AHA 2008 Guidelines for Choice of Pacemaker

~AV synchrony~

VVI

AAI

DDD

Pacing Mode Selection

Pacing Mode Selection