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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. Bradycardia /asystole cardiac output
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Brady Arrhythmia M.R Samieinasab, MD, Interventional Electrophysiologist Chamran Heart Hospital
Normal Impulse Conduction Sinoatrial node AV node Bundle of His Bundle Branches Purkinje fibers
Bradycardia /asystole cardiac output perfusion Symptoms AV dyssnchrony venous pressures ‘Pacemaker Syndrome’ Symptoms Symptom Basis
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 • Those related to problems with impulse conduction Sinus node AV node
Classification of Bradyarrhythmias • Problems with Impulse Formation • Sinus Arrest • Sinus Bradycardia • Chronotropic Incompetence • Brady/Tachy syndrome
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
Rate? 50-75 bpm • Regularity? Phasic variations • P waves? normal • PR interval? 0.12 s • QRS duration? 0.10 s Interpretation? 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).
Heart Rate 130 bpm 95 bpm 60 bpm Activity • 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 Running Walking Sleeping 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
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? 60 bpm • Regularity? Regular • P waves? Normal • PR interval? 0.36 s • QRS duration? 0.08 s Interpretation? 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)
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? 40 bpm • Regularity? Regular • P waves? Nl, 2 of 3 no QRS • PR interval? 0.14 s • QRS duration? 0.08 s Interpretation? Advanced AV Block
Third-Degree AV BlockComplete 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 Complete left bundle branch block Right bundle branch block and left posterior hemiblock Right bundle branch block and left anterior hemiblock
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
Diagnostic Test for Bradyarrhythmia: • EKG • Holter Monitoring • Implantable Loop Recorder • EPS
Investigation of the Site of AV Conduction Disease by Electrophysiologic Study (EPS)
Management : • Drug • Electrolyte Imbalance • Hypothyroidism • Post MI • PPM Implantation
Classification of Recommendations and Level of Evidence Level of Evidence:
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 1st degree) Epstein et al. “ACC/AHA/HRS Guidelines for Device-Based Therapy.” JACC Vol. 51, No. 21, 2008.
I I I IIa IIa IIa IIb IIb IIb III III III Sinus Node Dysfunction Permanent pacemaker implantation is indicated for sinus node dysfunction (SND) with documented symptomatic bradycardia, including frequent sinus pauses that produce symptoms. Permanent pacemaker implantation is indicated for symptomatic chronotropic incompetence. Permanent pacemaker implantation is indicated for symptomatic sinus bradycardia that results from required drug therapy for medical conditions.
I IIa IIb III I I IIa IIa IIb IIb III III Sinus Node Dysfunction (cont’d) 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. 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. Permanent pacemaker implantation may be considered in minimally symptomatic patients with chronic heart rate less than 40 bpm while awake.
I I I IIa IIa IIa IIb IIb IIb III III III Sinus Node Dysfunction (cont’d) Permanent pacemaker implantation is not indicated for SND in asymptomatic patients. 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. Permanent pacemaker implantation is not indicated for SND with symptomatic bradycardia due to nonessential drug therapy.
I I IIa IIa IIb IIb III III Acquired Atrioventricular Blocks in Adults Permanent pacemaker implantation is indicated for third-degree 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 third-degree 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.
I I IIa IIa IIb IIb III III Acquired Atrioventricular Blocks in Adults (cont’d) Permanent pacemaker implantation is indicated for third-degree 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. Permanent pacemaker implantation is indicated for third-degree 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.