Transcript Atrial Tachycardia - Thomas Jefferson University
PROPERTIES
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Arrhythmias - Part 1
Karima Sajadi, MD Sarah A. Stahmer MD Cooper University Hospital
Objectives
• • • • Understand the basic mechanisms that give rise to arrhythmias Review the basic types of tachy-arrhythmias and their treatment Review the presentation of wide complex tachycardias and their treatment Review the basic types of brady-arrhythmias and their treatment Slide 3
Mechanisms
• • • Enhanced automaticity – spontaneous depolarization of the myocytes that are normally not arrhythmogenic Triggered activity – depolarizations that are triggered by the preceding beat and occur during or after repolarization Reentry – existence of slow and fast conducting pathways that allow antero- and retrograde conduction Slide 4
Tachydysrhythmias
Tachydysrhythmias Regular Narrow complex Wide complex
Sinus Tachycardia Atrial Tachycardia Atrial Flutter AVNRT/AVRT
Ventricular tachycardia Pacer-mediated tachycardia SVT with pre-existing BBB SVT with rate-dependent BBB Narrow complex
MAT Atrial Fibrillation Atrial Flutter with variable block
Irregular Wide complex
Torsade des Pointes Ventricular fibrillation Slide 5
Regular Narrow-Complex Tachyarrhythmias
1. Sinus tachycardia 2. Atrial tachycardia 3. 3. Atrial flutter 4. 4. Paroxysmal supraventricular tachycardia – A. AVNRT (AV nodal reentry tachycardia) – B. AVRT or ORT (Orthodromic reciprocating tachycardia) Slide 6
Sinus Tachycardia
• • Physiologic response rather than a pathologic rhythm Maximal rate = 220 bpm – age (years) Slide 7
Sinus Tachycardia
• Causes: – Fever, anxiety, hypovolemia, thyrotoxicosis – Peripheral vasodilatation – Exogenous catecholamines (cocaine, amphetamine, dopamine) – Anticholinergics (TCAs, Benadryl) – LV dysfunction (CHF, myocardial ischemia) – RV dysfunction (PE, RV infarct) Slide 8
Sinus Tachycardia
• ECG Recognition: – Discrete P waves before every QRS, constant PR interval – Rate should vary in response to respirations, vagal stimulation, pain, stress – An isolated sinus tachycardia is a potentially life threatening rhythm until the underlying cause is identified and treated! Slide 9
Sinus Tachycardia
Slide 10
Atrial Tachycardia
• • • A single ectopic atrial pacemaker Causes: – Enhanced automaticity – Reentry – patients with a history of cardiac surgery – Triggered activity – think digoxin toxicity ECG recognition: – Atrial rate 150-250 bpm – slower than atrial flutter, with which it can be confused – Ectopic P wave morphology distinct from baseline sinus node P wave Slide 11
Atrial Tachycardia
Slide 12
Atrial Flutter
• • • Mechanism: regular microreentry circuit that rotates counterclockwise around right atrium Inherently unstable and converts to NSR or atrial fibrillation Causes: ischemic heart disease, congestive CM, PE, myocarditis, hyperthyroidism, etc Slide 13
Atrial Flutter
• • ECG recognition: – atrial rate 250-230, ventricular rate 75-150 bpm – if variable ventricular response then it is irregular – sawtooth wave pattern in inferior leads.
Treatment: – depends on time of onset (> or < than 48 hrs) – preserved or impaired heart function – presence of WPW syndrome Slide 14
Atrial Flutter: 1:1
Slide 15
Atrial Flutter 2:1
Slide 16
AVNRT
• Mechanism: – reentry at AV node or perinodal tissue.
– triggered by premature atrial conduction (PAC) – PAC conduction is blocked down the fast pathway (with a long refractory period) – conducted anterograde through the slow pathway (with a short refractory period) – reenters via recovered fast pathway Slide 17
AVNRT
• • • ECG recognition: – Narrow complex regular tachycardia at 140-280 bpm – P wave not seen due to simultaneous atria/ventricular activation Causes: – Atrial stretch (ACS, CHF) – irritability (exogenous catecholamines) – inflammation (pericarditis) Treatment: – Vagal maneuvers, adenosine – beta-blockers, diltiazem, digoxin Slide 18
AVNRT
Slide 19
Atypical AVNRT
Slide 20
AVRT or ORT
• • • Less common than AVNRT, difficult to distinguish from AVNRT on EKG Mechanism: – macroreentry through normal conducting system and an accessory AV pathway – impulse conducts anterograde down the AVN – reenters via an accessory pathway, resulting in narrow-complex tachycardia – P wave visible due to delayed activation of the atria ECG recognition: – P wave follows QRS Slide 21
ORT
• • Causes: same as AVNRT Treatment: – AV-nodal blocking agents are usually effective due to antegrade activation of the ventricles via the AVN – Ablation treatment has a 95% success rate Slide 22
AVRT or ORT
Slide 23
ORT
Slide 24
ORT after Adenosine
Slide 25
Irregular Narrow-Complex Tachyarrhythmias
1. Multifocal Atrial Tachycardia (MAT) 2. Atrial fibrillation 3. Atrial flutter with variable block Slide 26
MAT
• • Mechanism: – absent single dominant pacemaker – multiple atrial foci fire independently ECG recognition: – at least 3 different P wave morphologies – variable P-R, P-P, R-R intervals – isoelectric baseline present to distinguish from atrial fibrillation Slide 27
MAT
• Causes: – COPD, hypoxia – Pulmonary Hypertension – CHF – Theophylline toxicity – Electrolyte abnormalities (low K/Mg) • Treatment: – treat underlying cause – Magnesium, Verapamil may be beneficial Slide 28
MAT
Slide 29
Atrial Fibrillation
Slide 30
Atrial Fibrillation
• • Mechanism: – due to multiple reentrant wavelets between left and right atria ECG recognition: – irregularly irregular rhythm – disorganized atrial activity – no clear P waves between QRS complexes Slide 31
Atrial Fibrillation
• Causes: – Ischemic heart disease, HTN – pericarditis – “holiday heart” – thyrotoxicosis, etc • Treatment: – Rate control – Cardioversion (chemical or electrical) – Anticoagulation Slide 32
Atrial Flutter with Variable Block
• • Mechanism: – Atrial rate up to 300 bpm – not all depolarizations conduct through the AV node – especially in patients on medications that block AV node ECG recognition: – irregular narrow QRS complexes – the ratio of atrial flutter waves to QRS complexes varies (2:1, 3:1, etc) Slide 33
Atrial Flutter with Variable Block
Slide 34
Conclusion
• • This concludes part 1 of the arrhythmia presentation.
Continue to Arrhythmias Part 2 for the next installment of this lecture.
• Cases studies and references for this section are found at the end of Arrhythmias Part 3.