Download Tachycardias, an overview of acute and long term

Tachycardias, from the EMT to the
EP lab. An overview of acute and
long-term therapies
Nikhil Joshi, MD
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)
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
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
AVNRT
AVNRT
• Most common type of regular SVT
• Rates ranging from 100-280 BPM
• More common in women, typically presents in mid20s, 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
Typical AVNRT
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
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
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
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
Catheter ablation
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
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
Atrial flutter
• “sawtooth” pattern ECG – most common form
with negative p-waves inferiorly, and positive pwaves 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 250-350 bpm, with variable
conduction to the ventricle
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
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
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
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
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
Ventricular Tachycardia
• Monomorphic VT – often scar mediated
• Polymorphic VT (including Torsades)
– Acute ischemia
– Electrolyte disturbances
– scar
• Ventricular Fibrillation
– Acute MI
– Degeneration from another rhythm
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
Pre-excited tachycardia
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
Acute Treatment
• Focus on assessing hemodynamics/perfusion
• Synchronized Cardioversion or Defibrillation
for any hemodynamic instability
• ?Adenosine
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
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