Pearls from Dr. Angelo Biviano
Anti-tachycardia pacing = pacing the ventricle fast so that the ventricular tachycardia is suppressed by pre-empting of the depolarization of myocytes around a myocardial scar
Posted 08/25/16 10:32:15 AM by Anna Krigel
Vaughn Williams classification of antiarrhythmic drugs
- Class IA (moderate Na channel blocking) - procainamide, quinidine, disopyramide
- Class IB (mild Na channel blocking) - lidocaine, mexilitine, phenytoin
- Class IC (severe Na channel blocker) - flecainde, propafenone
- Class II - beta adrenergic receptor blockers
- Class III (K channel blocking) - amiodarone, dofetilide, ibutilide, sotalol, dronedarone
- Class IV - non-dihydropyridine calcium channel blockers
Posted 08/25/16 10:38:17 AM by Anna Krigel
- For stable VT, initiate antiarrhythmic drug therapy
- IV amiodarone
- IV lidocaine
- IV procainamide
- Urgent electrical cardioversion
- For chronic therapy
- Beta blockers - offer survival benefit
- ICD therapy - offer survival benefit
- Ablation - kills tissue in scar where tachycardia is coming from, though no survival benefit
- Antiarrhythmic drug therapy - primarily sotalol or amiodarone, though no survival benefit
Posted 08/25/16 10:47:27 AM by Anna Krigel
Long QT predisposes to torsades de pointes -> treatment can be to place temporary pacemaker and pace the patient faster to lower the QT interval
Lidocaine shortens QT interval
Posted 08/25/16 10:48:38 AM by Anna Krigel
For further reading...
Posted 08/25/16 10:54:15 AM by Anna Krigel
Syncope in Elderly
- Syncope = decrease in brain perfusion leading to loss of postural tone
- Neurally mediated (neurocardiogenic syncope, carotid hypersensitivity)
- Orthostasis (PD c/b ANS dysfcn, multi-system atrophy, drugs, DM)
- Arrhythmia (Afib, AV block, SSS, VT)
- CV/structural (MI, AS, PE)
Posted 11/07/16 09:14:15 AM by Matthew Cummings
Characteristics of Complete Heart Block
- More P waves than QRS complexes exist and no relationship (AV dissociation) exists between them.
- Escape rhythm may arise within the AV node (resulting in a narrow QRS complex), or lower in the conduction system (producing a wide QRS complex).
- The ventricular rate varies from 30–40 beats/min.
- Atrial rate is faster than the ventricular rate (60–100 beats/min) presumably in response to the hemodynamic consequences of the block (relative hypotension).
Posted 11/07/16 09:21:07 AM by Matthew Cummings
Accelerated junctional rhythm
- Rate of an AV junctional pacemaker exceeds >> rate of sinus node due to increased automaticity in AV node + decreased automaticity in sinus node.
- Narrow complex (QRS < 120ms), ventricular rate ~60 – 100 bpm
- Retrograde P waves may be present (inverted in the inferior leads, upright in aVR + V1).
- AV dissociation may be present with the ventricular rate usually greater than the atrial rate.
- Junctional Escape Rhythm: 40-60 bpm
- Accelerated Junctional Rhythm: 60-100 bpm
- Junctional Tachycardia: > 100 bpm
- Causes of junctional rhythms
- Digoxin toxicity
- Myocardial ischaemia
- Cardiac surgery (classically mitral valve)
Posted 11/07/16 09:28:09 AM by Matthew Cummings
When to consider PPM?
- Symptomatic bradycardia that cannot be reversed (meds, electrolytes, etc)
- Mobitz II or CHB even if asymptomatic (ventricular/junctional escape = unreliable = high-risk for hemodynamic collapse)
- Formal indications below
Posted 11/07/16 09:43:53 AM by Matthew Cummings
For further reading...
Posted 11/07/16 09:46:33 AM by Matthew Cummings
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