Brady Arrhythmia M R Samieinasab MD Interventional Electrophysiologist

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 venous pressures cardiac output perfusion ‘Pacemaker Syndrome’ Symptoms

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: – – – – – 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 -60 bpm 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

• 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 5 x 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

• Rate? • Regularity? • P waves? • PR interval? • QRS duration? Interpretation? 60 bpm Regular Normal 0. 36 s 0. 08 s 1 st 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)

• 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 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 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/ Procedure/Treatment administer 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: – – Symptomatic bradycardia Sinus Node Disease (SND), or Sick Sinus Syndrome Complete Heart Block Chronotropic Incompetence • Usually excludes “low grade” blocks (Mobitz I and 1 st 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. 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. 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 second- or 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 infra. His 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. Permanent pacemaker implantation is indicated for type II second-degree AV block. 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 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. I IIa IIb III 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?