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TACHYARRHYTHMIAS (treatment (Antiarrhythmic drugs (Often the first line of…
TACHYARRHYTHMIAS
treatment
Antiarrhythmic drugs
- Often the first line of treatment
- Side effects: severity of heart failure, pro-arrhythmic effects
- Class I – sodium channel blocking agents
– Reduce the ability of the cell to depolarize
– Slowed conduction
• 1A: prolong the refractory period
– e.g.: quinidine, procainamide, disopyramide
• 1B: shorten the refractory period
– e.g.: lignocaine, mexyletine
• 1C: little effect on the refractory period
– e.g.: flecainide, propafenone
- Class II – Beta-blockers
– ↓ activity of sympathetic nervous system
• e.g.: propranolol, metoprolol, atenolol,esmolol
- Class III – Potassium channel blockers
– prolong refractoriness
• e.g.: amidarone, sotalol, dofetilide
- Class IV – Calcium channel blockers
– ↓ automaticity of the SA and AV node
– Prolong action potential
• e.g.: verapamil, diltiazem
- Class V – cardiac glycosides
– ↑ activity of parasymphathetic nervous system • e.g.: digoxin
- Class VI
– Hyperpolarization of the SA and AV node
– Rapid and short-acting
• e.g.: adenosine
Ablation
- destruction of a fragment of tissue responsible for the formation of arrythmias
- irreversible
- AVNRT, (AVRT) with an accessory pathway, including WPW syndrome, Normal heart VT, Atrial flutter, Atrial tachycardia, Atrial fibrillation.
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diagnostics
- Symptoms:
• Palpitations – frequency, regularity, onset.
• Loss of consciousness – duration, return of consciousness
• Comorbidities
• Medications
• Family history
- Standard ECG - 10-15 sec.
- Holter monitor – 24-48 hours recording period
- „tele-ECG” – activated by a patient
- Event Recorder – activated by a patient (upon feeling a symptom), worn for 30 days
- Implantable Loop Recorder (ILR) – activated automatically or by a patient
– under the skin in a pectoral area – several months of recording
tests
- Treadmill test – arrythmias provoked by exercise
- Tilt Table Test – diagnostics of recurrent syncope
- echocardiogram – diagnostics of structural heart disease
- Pharmacological assays – propafenon, adenosine.
- Blood tests – electolytes, glycemia, hormones
- Genetic tests
- Esophageal Electrophysiological Procedure
– Non-invasive – electrode inserted into esophagus
– Induction of supraventricular arrhythmia
– Only supraventricular arrhythmias can be diagnosed
- Electrophysiological Study - EPS
– Invasive which tests electrophysiological properties of the heart
– Induction of arrhythmia
– Possibility of treatment – RF ablation
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Mechanisms
Impulse formation
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Disorder
- Too fast = tachycardia
e.g. sinus tachycardia
ectopic atrial tachycardia
nonparoxysmal junctional tachycardia (NPJT)
accelerated idioventricular rhythm (AIVR)
- Too slow = bradycardia (e.g. sinus node dysfunction)
Impulse conduction
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Disorder
• Atrial flutter
• Atrial fibrillation
• AVRT
• AVNRT
• Ventricular tachycardia
• Ventricular fibrillation
nomenclature
- Paroxysmal – sudden onset and sudden cessation
- Sustained – time period > 30 sec & require intervention for termination
- Non-Sustained – < 30 sec & Spontaneously terminates
- Recurrent – periodically & separated by periods of no tachycardia longer than the periods of tachycardia.
- Incessant – periods of tachycardia are longer than normal sinus rhythm
- Monomorphic – originate from a single focus, QRS (P) complex similar, RR (PP) intervals are equal
- Polymorphic – originate from multiple foci, QRS (P) complex different, RR (PP) intervals are unequal
VENTRICULAR ARRHYTHMIAS
- Benign (idiopathic)
• ventricular tachycardia / ectopy from RVOT/LVOT/Ao
• fascicular ventricular tachycardia
we use ablation and pharmacotherapy
- malignant
• VT/VF + after MI
• VT/VF + cardiomyopathies (DCM, HCM, ARVC)
• VT/VF + chanellopathies (LQTS, Brugada syndrome, CPVT)
we use ICD and ablation
Pacemaker cells
- Sinoartial node - 60-100 BPM
- Atrioventricular node - 40-60 BPM
- His-Purkinje fibers - 20–40 BPM
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ECG distinction between supraventricular tachycardia (SVT) with bundle branch block and ventricular tachycardia (VT)
- VT is more likely than SVT with bundle branch block where there is:
a very broad QRS (>0.14 s)
atrioventricular dissociation
a bifid, upright QRS with a taller first peak in V1
a deep S wave in V6
a concordant (same polarity) QRS direction in all chest leads (V1–V6)