COMMON ARRHYTHMIAS Diagnosis and Therapy

Transcription

1 COMMON ARRHYTHMIAS Diagnosis and Therapy Zachary D. Goldberger, MD, FACC, FHRS Assistant Professor of Medicine Division of Cardiology UW School of Medicine Harborview Medical Center

2 FINANCIAL OR OTHER RELATIONSHIP DISCLOSURE: None

3 KEY POINT Regular or irregular Irregular Regular

4 Sinus Tachycardia Sinus tachycardia: sinus rhythm with a HR >100 bpm Short differential diagnosis: Physiologic (e.g., exercise, excitement, pregnancy) Pain /anxiety Drugs (e.g., alpha/beta-agonists, stimulants, withdrawal) Hypovolemia (e.g., bleeding, vomiting, diarrhea) Heart failure (CO=HR x SV) Pulmonary embolism Acute MI Endocrine (e.g., hyperthyroidism, pheochromocytoma)

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6 Are there P waves?

7 Atrial Fibrillation with Rapid Ventricular Response Most common pathologic arrhythmia Hallmarks: irregularly irregular, no P waves AVERAGE rate >100 bpm (count QRS s, multiply by 6) Narrow complex (when ventricles activated normally) May be acute, paroxysmal, or chronic Always try to account for etiology

8 Atrial fibrillation with a rapid ventricular response: irregularly irregular, no P waves, >100 bpm Some associated causes/conditions: Aging Hyperthyroidism Hypertension Post-operative (esp post cardiac surgery) Valvular disease (esp mitral stenosis) Sepsis/infection (esp endocarditis) Coronary artery disease (including ischemia/acs) Pulmonary disease (COPD, PE)

9 Mechanism of Atrial Fibrillation Synchronized Activation Multiple Wavelets

10 KEY POINT When you see an irregularly irregular rhythm, suspect atrial fibrillation (and confirm by absence of P waves)

11 Atrial Flutter Common pathologic arrhythmia Hallmarks: saw tooth flutter waves, may be regular or irregular Rate depends on degree of conducted flutter waves (usually ) Narrow complex May be acute, paroxysmal, chronic

12 Atrial Flutter Atrial flutter can be regular or irregular Conduction may be variable (e.g., 3:1, 4:1) Caution! Irregularity may mimic atrial fibrillation, but irregularity not random 300/min, so rates approximate 150 (2:1), 100 (3:1), 75 (4:1), etc

13 Atrial flutter with 2:1 conduction (150 bpm). The saw-tooth appearance is not always easily apparent with 2:1 conduction.

14 KEY POINT When you see a narrow complex tachycardia at ~150 bpm, suspect atrial flutter with 2:1 conduction

15 CASE 1 A 27 year-old woman comes to the ED with palpitations which began 2 hours ago. She says she was watching television when she suddenly began to feel as though her shirt was fluttering and had a sensation of someone pounding on her neck. She has had similar episodes occurring twice yearly for approximately 5 years, but now they are increasing--she has had 5 episodes during the past 6 months. Her previous episodes have always started and resolved suddenly, never lasting longer than 10 minutes; she has noticed that they occasionally resolve with coughing. Her medical history otherwise is unremarkable, and she takes no medications. Her family history is significant for the death of her father from a myocardial infarction at age 55 years. The patient's vital signs reveal a HR of 180/min and her BP is 124/75 mmhg. She appears mildly anxious, but alert and oriented. Physical examination reveals prominent jugular venous pulsations and tachycardia. She has no carotid bruits, and the remainder of her exam is normal. An ECG is performed:

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17 Which of the following is the most appropriate next step in management? A. Administration of intravenous adenosine B. Carotid sinus massage C. Direct current cardioversion D. Observation only E. Oral metoprolol therapy

18 CASE 1, cont d Carotid sinus massage is performed. Her pulse remains 180/min and blood pressure is now 100/60 mmhg. The patient remains alert and oriented but appears increasingly anxious. Intravenous adenosine is administered, after which normal sinus rhythm is restored with a pulse of 85/min. A. Flecainide therapy B. Metoprolol therapy C. Reassurance only D. Refer for radiofrequency ablation E. Refer for an implantable cardioverter-defibrillator

19 AV Nodal Reentrant Tachycardia

20 Clinical syndrome Paroxysmal SVT (PSVT) Subset of all SVTs, but often simply called SVT Narrow complex Regular, rapid, abrupt onset and termination P waves, if seen, are not of sinus origin Defined as: AV nodal reentrant tachycardia (AVNRT) AV reentrant tachycardia (AVRT) (Ectopic) atrial tachycardia (AT)

21 Paroxysmal SVT (PSVT) KEY POINT: Mechanism is either: Automatic (ectopic atrial tachycardia) Reentrant (AVNRT, AVRT) AV nodal reentry (Ectopic) atrial tachycardia AV reentry Note: atrial flutter is also a reentrant rhythm, and may be paroxysmal, but not typically classified as PSVT

22 Which is not a common symptom of a supraventricular tachycardia? A.Chest pain (if underlying heart disease) B.Dyspnea C.Light-headedness D.Palpitations E.Syncope

23 AV Nodal Reentrant Tachycardia (AVNRT)

24 AV Nodal Reentrant Tachycardia Regular, narrow complex tachycardia, sudden onset and termination Usually bpm (range 110 to >250) Most common of the PSVTs, more common in young adults without structural heart disease, >70% women Subtle findings on ECG aid in diagnosis retrograde P waves in certain leads Don t mistake for junctional tachycardia

25 Acute Termination: AVNRT Vagal maneuvers always try first (carotid sinus massage, Valsalva maneuver) If ineffective, or possibility of carotid plaque (i.e., elderly, bruit present), administer adenosine (6 mg IV, may increase to 12 mg, 2-3 times)

26 Long-Term Therapy: AVNRT 3 strategies to treat/prevent AVNRT: Reassurance Pharmacologic therapy Invasive therapy

27 Long-Term Therapy: AVNRT Pharmacologic therapy: flecainide/propafenone during symptomatic episodes (pill-in-the-pocket) Antiarrhythmics carry proarrhythmic risk, careful selection of appropriate patients AV nodal blockers Radiofrequency ablation: ~99% curative procedure, low complication rate (Low) risk of AV node injury/ablation, and risk of invasive EP study itself

28 CASE 2 A 35 y/o man was playing basketball when he experienced the acute onset of palpitations. They lasted approximately 3 minutes, and subsided when he kneeled down. His teammates encouraged him to present to his internist the next day. He has experienced palpitations for nearly 20 years. He was referred to a cardiologist during college who did not feel further cardiac testing was needed. He takes no medications, and his examination is unremarkable. His ECG is shown below:

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30 What do you tell the patient? A. Surgery will offer the most effective therapy for this condition. B. Your palpitations are likely due to anxiety. C. This problem may worsen as you get older. D. Antiarrhythmics are less effective than a catheter ablation. E. You have a high risk of sudden death.

31 SA node Wolff-Parkinson-White Pattern/Syndrome AV node Bypass Tract Substrate for AVRT AVRT=reentry around bypass tract Short PR (<120 msec) Delta wave (slurring/notching upstroke of QRS) QRS >100 msec

32 WPW and AVRT Ganz and Friedman. N Engl J Med 1995;332:

33 Asymptomatic Preexcitation (WPW Pattern) Short PR (<120 ms) Delta wave (slurring/notching upstroke of QRS) QRS >100 ms

34 Long-Term Therapy: AVRT Radiofrequency ablation: ~90-95% curative, low complication rate Treating asymptomatic WPW pattern is controversial Not every bypass tract capable of rapid conduction and risk of pre-excited a-fib is generally low, and risk-stratification requires careful evaluation Patients with high-risk occupations (e.g., bus driver, pilot) often receive mandatory ablation

35 AVRT (before) and WPW (after)

36 KEY POINT Suspect AVRT when the ECG in sinus rhythm shows a WPW pattern (i.e., pre-excitation)

37 PSVT: Summary Slide Ferguson J, DiMarco J. Circulation 2003;107:

38 KEY POINT Adenosine is a safe, effective therapy for narrow-complex tachycardias suspected to be PSVT (i.e., diagnostic, potentially therapeutic)

39 A 65 y/o man presents with chest pain. The first ECG is taken on admission. He undergoes a procedure. The second ECG is performed 3 hours later.

40 What is the most appropriate step in management (after seeing the 2 nd ECG)? A. Activate the cardiac catheterization laboratory B. Administer IV amiodarone C. Administer IV lidocaine D. Direct current cardioversion E. Observation only

41 Acute inferolateral MI (ST elevations in II, III, avf, V5, V6)

42 Acute MI is resolving, likely treated with PCI or thrombolytics Beats 6-11: accelerated idioventricular rhythm (AIVR) AIVR common with acute MI, associated with reperfusion after thrombolytic agents or PCI, occurring spontaneously This arrhythmia is generally short-lived (minutes or less), and usually requires no specific therapy. Not a new BBB. No need for BBs, amiodarone, lidocaine, cath lab reactivation, troponins, etc

43 An 85 y/o man with severe emphysema is admitted to the medical intensive care unit due to acute shortness of breath and tachycardia. His pulse is irregular; you perform an ECG:

44 What is the most appropriate step in management? A. DC cardioversion B. IV amiodarone C. IV beta-blockers and initiate anticoagulation once stable D. Oral theophylline E. Oxygen and nebulizers

45 Multifocal Atrial Tachycardia 1 2 3

46 Multifocal Atrial Tachycardia 3 consecutive, different (non-sinus) P waves at rapid rate, varying PR interval Suspect with irregularly irregular rate, especially with COPD, pulmonary hypertension, coronary/valvular heart disease, hypomagnesemia, theophylline therapy First-line treatment: management of the underlying condition. IV magnesium may also be helpful even with normal magnesium levels; rate control with BBs, CCBs Antiarrhythmic medications in general are not helpful in suppression of multifocal AT Do NOT cardiovert (can provoke VT)

47 CAUTION! A-fib mimic! Need to look for p- waves!

48 KEY POINT When you see an irregularly irregular rhythm, suspect atrial fibrillation (but confirm by absence of P waves)

49 AV Block Delay between atrial and ventricular activation allows ventricle time to fill Excessive slowing or interruption = AV block

50 AV conduction disorders: 2 nd major cause of bradyarrhythmias (after SA node dysfunction) Key clinical decision: Does this patient need a pacemaker? Decision (usually) relies on three factors: Symptoms Site of block Degree of block AV block

51 Key Questions What is the degree of block? 1 st, 2 nd, 3 rd degree (complete) What is the most likely level of block / delay? Nodal (narrow QRS) often benign Infranodal (wide QRS) potentially lethal

52 Causes Autonomic factors ( vagal tone) RCA ischemia / infarct (AV nodal artery in 85%) Mediations (β-blockers, Ca ++ -channel, digitalis) Electrolyte (e.g., hyperkalemia) Inflammatory (rheumatic fever, SLE, myocarditis) Infectious (Lyme, toxoplasmosis, Chagas, endocarditis ) Congenital Anterior MI Infiltrative dz (e.g., amyloid, sarcoid, lymphoma) Degeneration / fibrosis of conduction tissue Neuromuscular dz (e.g., myotonic dystrophy, Kearns-Sayre, Erb s dystrophy) Iatrogenic (e.g., surgery, post-ablation)

53 Prolonged PR interval (First-degree AV block)

54 Not block, per se delay Prolonged PR interval (First-degree AV block) P waves (usually sinus) followed by QRS with uniformly prolonged PR (>200 ms) Usually ms, but can be longer All impulses transmitted from atrial ventricles

55 2 nd Degree AV Block Characterized by intermittently dropped QRS complexes Mobitz type I (AV Wenckebach) Mobitz type II Wenckebach AV block = nodal Mobitz type II AV block = infranodal Karel Wenckebach ( )

56 2 nd Degree, Mobitz I AV Block

57 AV Wenckebach Each stimulus from atria has PROGRESSIVE difficulty traversing the AV node to ventricles (i.e., node increasingly refractory) Atrial impulse ultimately not conducted ( dropped QRS ) Cycle followed by relative recovery, and starts all over

58 Mobitz II Type II AVB is infranodal (wide QRS present) Abruptly dropped QRS: without PR prolongation without the shortening of PR after dropped QRS

59 Complete (3 rd Degree) AV Block

60 Complete (3 rd Degree) AV Block NO stimuli are transmitted from the atria to the ventricles Each paced independently SA node usually the pacemaker Ventricles paced by nodal or infranodal escape pacemaker, located below point of block Rate usually bpm

61 Atrial rate faster than ventricular rate Ventricular rate slow, usually regular Regularity is key remember, 2 nd degree block irregular (group beating) No consistent P-QRS relationship (AV dissociation)

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63 Recipe for 3 rd degree (complete) heart block: 1)Bradycardia, REGULAR (usually <50 bpm) 2)Atrial rate > Ventricular rate 3)AV dissociation

64 Summary: Atrioventricular Conduction Disturbances Prolonged PR/first degree (nodal delay) 2 nd degree Mobitz I (intranodal) 2 nd degree Mobitz II (infranodal) Complete/3 rd degree (intra or infranodal)

65 KEY POINTS 3 rd degree block is slow and regular, without dropped QRS s Mobitz I and II are irregular (pauses due to dropped QRS s)

66 Permanent Pacemakers Key indications to know for ABIM exam: Symptomatic sinus bradycardia (including required drug therapy for medical conditions [i.e., betablockers for HF]) Symptomatic AV block Mobitz II AV block usually requires a pacemaker Do NOT implant for reversible causes (i.e., Lyme carditis with AV block) Note: 2 nd /3 rd degree AV block that occurs after STEMI: Anterior: does not usually improve (necrosis) Inferior: can improve (vagally mediated)

67 Implantable Cardioverter-Defibrillators Key indications to know for ABIM exam: Survivors of VT/VF arrest (with nonreversible cause) Ischemic/nonischemic cardiomyopathy, LVEF 35%, NYHA Class II or III Need to be >40 days post-mi Optimize medical therapy for at least 3 months prior to ICD (i.e., increase ACE, BB) Consider biventricular ICD for symptomatic HF patient with LVEF 35%, and wide QRS complex (e.g., LBBB)

68 A 79 y/o woman is brought into the ED by EMS. Her neighbor found her in the hallway of their apartment building, obtunded. No records are available.

69 What is the most appropriate next step in management? A. Activate the cath lab B. Administer naloxone C. Emergent hemodialysis D. Insert a transvenous pacemaker E. Order a brain MRI

70 Hyperkalemia Mild-Moderate Moderate-Severe Severe

71 You can now. Identify and treat paroxysmal SVT Distinguish atrial fibrillation and MAT Recognize a reperfusion arrhythmia Recognize and differentiate AV block Identify who may need a pacemaker or ICD Recognize the ECG signature of a life threatening electrolyte abnormality

72 AVNRT AVRT Narrow-complex Narrow or wide complex Reentry: fast and slow AV pathways Reentry: AV node and bypass tract Young, generally female (32±18 y/o) Younger (23±14 y/o) No risk of sudden death Baseline ECG: normal Tachycardia may show no P waves, (don t confuse with junctional tachycardia) or P waves just after QRS complex Low risk of sudden death (preexcited atrial fibrillation) Baseline ECG: WPW Tachycardia may show P waves more distinct from QRS complex