Tachycardias, from the EMT to the EP lab. An overview of acute and long-term therapies. Nikhil Joshi, MD

Transcription

1 Tachycardias, from the EMT to the EP lab. An overview of acute and long-term therapies Nikhil Joshi, MD

2 Talk outline Narrow complex tachycardia Regular SVT AVNRT, AVRT, AT Atrial Flutter/Fibrillation Wide complex tachycardia Ventricular tachycardia SVT with aberrant conduction (LBBB, RBBB) Antidromic SVT (accessory pathway mediated)

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6 Supraventricular Tachycardia AVNRT This is a reentry tachycardia with a functional, anatomic circuit, involving predominantly the AV Node AVRT this is a reentry tachycardia with an anatomic circuit involving the AV Node, the ventricle and an accessory pathway AT this is usually a tachycardia of abnormal automaticity, resulting from firing of a focus besides the sinus node

7 Regular, narrow complex tachycardia Acute treatment focuses include hemodynamic stabilization and supportive care Mostly these are well tolerated, even with heart rates approaching 200s (younger patients) Often express symptoms of racing heart, feeling dizzy, sensation in throat Syncope rare, consider degeneration to another rhythm, or significant hypotension

8 AVNRT

9 AVNRT Most common type of regular SVT Rates ranging from BPM More common in women, typically presents in mid- 20s, but very young and very old cases also seen Difficult to see p-waves on ECG pseudo s-wave in III pseudo R in V1

10 Typical AVNRT

11 Acute Therapy Vagal maneuvers Valsalva/coughing, Carotid Sinus Massage, Ice/cold water immersion Enhance Vagal Tone Cause slowing of conduction through the AV Node (and prolongs refractoriness) Can be effective in terminating AVNRT via effects on either the slow or fast pathway

12 Carotid Sinus Massage Patient should be supine with extension of neck Apply firm, steady pressure for 5-10 seconds L carotid may be more effective Be cautious in elderly patients, and avoid bilateral carotid stimulation

13 Adenosine Acts upon AV node in manner similar to Ach Causes cellular hyperpolarization, also causing prolonged refractoriness Rapid onset/offset, but warn patients about symptoms Effective in termination of reentrant arrhytmias that are dependent upon AV nodal conduction Sometimes can also terminate or transiently suppress focal arrhythmias Caution of use in Wide Complex Rhythms

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16 Other considerations for SVT Beta blockers Calcium channel blockers Amiodarone Less effective for acute termination, but can be considered as therapy for prevention, especially if patients prefer to avoid ablation

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18 Catheter ablation

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23 Orthodromic AVRT Narrow complex tachycardia Acute evaluation and treatment similar to that of AVNRT This is still a NARROW complex tachycardia (conduction is DOWN the AV node, and UP an accessory pathway) Vagal maneuvers, adenosine, AVN blocking agents still effective acute therapy

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29 Atrial Tachycardia Typically an ectopic focus outside of the sinus node likely enhanced automaticity More likely to see in patients with underlying heart disease Less responsive to adenosine, may slow with AV nodal blockers Ablation focuses on localizing site of impulse initiation and ablating

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32 Atrial flutter sawtooth pattern ECG most common form with negative p-waves inferiorly, and positive p- waves in V1 (counterclockwise) Atypical forms also exist, especially with underlying structural heart disease (mitral valve) or prior cardiac surgery/ablation May be difficult to discern p-waves if very rapid conduction Atrial rates often bpm, with variable conduction to the ventricle

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34 Acute treatment Hemodynamic stabilization Response to pharmacologic agents is variable Adenosine will slow transiently, can be helpful to see the flutter waves AVN blockers can help slow, unlikely to convert Amiodaroe may slow or convert (be cautious with unknown duration, unless unstable Cardioversion if unstable only, especially if duration or anticoagulation status unknown

35 Catheter ablation Definitive RX for typical flutter (medications less effective, often not well tolerated) Can be curative for various atypical forms as well, but often recur

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41 Atrial fibrillation ECG - irregularly irregular, no clear discernable p waves ( coarse afib can appear like p-waves) More common in older population Can exist in otherwise young/healthy hearts

42 Acute treatment Rate control with AVN blocking agents No response to adenosine may see transient slowing only Electrical cardioversion if unstable, but again be weary if duration and anticoagulation status unknown

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45 Atrial Fibrillation Triggers Pulmonary Veins Superior Vena Cava IVC, Coronary Sinus, others Ablation focuses on electrical isolation of the pulmonary veins, thought to be the primary trigger for atrial fibrillation

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51 Ventricular Tachycardia Monomorphic VT often scar mediated Polymorphic VT (including Torsades) Acute ischemia Electrolyte disturbances scar Ventricular Fibrillation Acute MI Degeneration from another rhythm

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53 SVT with aberrancy Often AVNRT or AVRT with pre-existing or rate-related bundle branch block Can also be atrial fibrillation or flutter Aberrancy can be transient, having an old ECG is helpful but not always available

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56 Pre-excited tachycardia

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59 WCT 80% is VT (wider = more likely VT) If history of MI, structural heart disease then VT even more likely VT often has northwest axis negative in lead I and inferior leads

60 Acute Treatment Focus on assessing hemodynamics/perfusion Synchronized Cardioversion or Defibrillation for any hemodynamic instability?adenosine

61 Catheter Ablation Approach for SVT with aberrancy and Antidromic tachycardia is similar to narrow SVT ablation VT ablation typically focuses on identifying areas of scar, that are known to be triggers In some cases, a focal PVC or area can trigger polymorphic VT/VT and can be targeted

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63 Summary/Conclusions Most tachycardias, both narrow and wide are amenable to some form of definitive therapy after acute stabilization In the case of most SVTs, often catheter ablation is curative Afib and VT tend to recur, especially in sicker patients with chronic heart conditions