TỔNG QUAN Bradyarrhythmias brady

Bradyarrhythmias What is bardyarrhythmia? • Abnormally slow heart rhythms • Can be caused by failure of the SA node to start the normal pacemaker impulse or defects in the conduction system that prevent the electrical impulses from reaching the ventricles • A very common disorder, affecting millions of people worldwide SA node AV node Symptoms of Arrhythmias • Syncope or presyncope • Chest tightening • Dizziness • Neck pulsations • Fatigue • Seizures • Shortness of breath • Exercise intolerance • Palpitations • Confusion Patient Assessment Basic indication for pacing: Symptomatic bradycardia How Are Bradyarrhythmias Diagnosed? • History and Physical Examination • EkG/ECG (Electrocardiogram) • Continuous ECG Recording ( Holter) • Graded Treadmill Test • External loop recorder • Insertable loop recorder (Reveal Plus) • Cardiac Electrophysiology Study (EP study) Types of Bradyarrhythmia Bradycardias •Sick Sinus Syndrome –Sinus Bradycardia –Sinus Pause SA node –Sinus Arrest –Bradycardia-Tachycardia –Chronotropic Incompetence AV node •Heart block –First Degree AV block –Second Degree AV Block –Complete AV Block –Bifascicular and trifascicular block Sick Sinus Syndrome (Sinus Node Dysfunction ) • Sinus bradycardia • Sinus arrest • SA block • Brady-tachy syndrome • Chronotropic incompetence 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 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 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 Bifascicular Block 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 Therapies Drug therapy Pacemaker Considerations: Drug Therapy • Common drugs: sympathomimetics, antiarrhythmics • Drug therapy may be life saving for emergency or temporary uses • Drug therapy is not recommended for long-term therapy Considerations: Drug Therapy vs Pacing • Compliance • Side effects • Tolerance • Long-term cost Therapy Options for Bardycardia •Medications are not effective in treating slow heartbeats •Treated by implanting a pacemaker Considerations: Paced vs Nonpaced 50-60% mortality without pacing at the end of the first year Considerations: Paced vs Nonpaced Shaw DB, Kekwick CA, Veale D, et al Survival in second degree AV block Br Heart J 1985;53:587-593 Pacing Indications Sick Sinus Syndrome • Sinus node dysfunction with documented symptomatic sinus bradycardia In some patients , bradycardia is iatrogenic and will occur as a consequence of essential long-term drug therapy of a type and dose for which there are no acceptable alternatives • Symptomatic chronotropic incompetence • Chronic heart rate < 30 bpm in minimally symptomatic patients while awake JACC Vol 31, no April 1998, 1175-1209 Pacing Indications Heart Block • Third-degree AV block at any anatomic level associated with any one of the following conditions: – Bradycardia with symptoms presumed to be due to AV block – Arrhythmias and other medical conditions that require drugs that result in symptomatic bradycardia – Documented periods of asystole greater than or equal to seconds or any escape rate less than 40 beats per minute (bpm) in awake, symptom-free patients – After catheter ablation of AV Junction – Postoperative AV block that is not expected to resolve – Neuromuscular diseases with AV block such as myotonic muscular dystrophy, Kearns- Sayre syndrome, Erb’s dystrophy (limb-girdle), and personal muscular atrophy JACC Vol 31, no April 1998, 1175-1209 Pacing Indications Heart Block • Second-degree AV block regardless of type or site of block, with associated symptomatic bradycardia JACC Vol 31, no April 1998, 1175-1209 Pacing Indications Chronic Bifascicular and Trifascicular • Intermittent third-degree AV block • Type II second-degree AV block JACC Vol 31, no April 1998, 1175-1209 Case Study: Sinus Pause Background: • 74 Year-old Female, Led active and independent life • Suffered multiple unexplained syncopal episodes and spells of seizure nV 0.4 0.2 08:23:21 0.0 -0.2 -0.4 :21 :22 :23 :24 :25 :26 :27 :28 :29 0.4 0.2 8:23:29 0.0 -0.2 :29 :30 :31 :32 :33 :34 :35 :36 :37 -0.4 0.4 0.2 0.0 08:23:37 -0.2 -0.4 :37 :38 :39 :40 :41 :42 :43 :44 :45 •Bradycardia with second pause and PVCs •Discontinued seizure medication •A dual chamber pacemaker was implanted Case Study: Heart Block Background: • 56 Year-old Female • syncopal episodes over nine months • Bruising and cuts from falling •2 minute asystole with burst of P wave activity •no subjunctional escape beats • idio-ventricular beats and gradually resumes normal conduction •Diagnosed with infra-Hisian AV block •Dual-chamber pacemaker implanted Case Study: Sinus Arrest Background: • 83 year-old female • Presented at emergency room after syncopal episode • Suffered burns and tendon damage from falling against radiator Ten-second slowing in heart rate followed by an eight-second sinus arrest Pacemaker implanted Patient has experienced no further syncope ... Electrophysiology Study (EP study) Types of Bradyarrhythmia Bradycardias •Sick Sinus Syndrome –Sinus Bradycardia –Sinus Pause SA node –Sinus Arrest –Bradycardia-Tachycardia –Chronotropic Incompetence... Syndrome (Sinus Node Dysfunction ) • Sinus bradycardia • Sinus arrest • SA block • Brady- tachy syndrome • Chronotropic incompetence Sinus Node Dysfunction – Sinus Bradycardia • Persistent slow rate from... pause 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