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20 Cards in this Set
- Front
- Back
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Triggered EAD
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Cellular; Before full repolarization, prolonged AP; Pause dependent
Screwed up K+ channel or leaky Na+ channel |
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Triggered DAD
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Cellular; After full repolarization; Excessive Cytoplasmic Ca+2
Ca+2 induced rapic pacing |
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Re-entry
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Ultrastructural not cellular!
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Ibutilide pharmacokinetics
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Potent Class III antiarrhythmic drug; IV use
Rapid effect (w/in minutes) NO hemodynamic effects 1 mg over 10 min (continue to monitor) |
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Ibutilide
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Effective in termination of recent onset of AF
High efficacy for acute termination of new onset AF/AF Can cause ventricular arrhythmias; Paroxysmal Ventricular Fibrillation (pause between T and QRS complex); Long QT syndrome (TdP) |
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Long QT syndrome/TdP
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All block the slowly activating K+ channel Ikr
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Drugs at risk for TdP
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Amiodarone, Ibutilide, quniidine, sotalol, Chloroquine, methadone and more
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Long QT syndrome Tx
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Discontinue
MgSO4 2 g IV bolus over 1-2 minutes K+ repletion to 4.5 to 5.0 mEq/L (shortens AP) Isoproterenol infusion |
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Catecholaminergic Polymorphic Ventricular Tachycardia Clinical presentation
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Collapsed while running; in VF; varrying QRS appearance; Recurrent syncope (always during physical extertion)
PVC's Bidirectional VT!!!! Arrhythmias immediately resolve after exercise was stopped |
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CPVT outlook
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Mortality in untreated cases 30-50% before age 20-30
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CPVT genetics
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Dominant inherited syndrome associated with mutations in the Cardiac Ryanodine Receptor Gene (RyR2: Ca+2 induced Ca+2 release channel)
Recessive: mutation in Calsequestrin gene CASQ2 Both result in abnormal elevated cytoplasmic Ca+2 |
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What drug can cause CPVT?
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Digoxin
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RyR2 Ca+2 channel funciton
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Intracellular channel between the SR and the cytoplasm
Responsible for the controlled systolic release of Ca+2 from the SR-->cardiac contraction Mutations-->leaky channel-->elevated intracellular Ca+2 |
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What drugs can activate the RyR2 channel?
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Epinephrine w/ B-receptor-->protein kinase
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Tx of CPVT
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Decrease adrenergic stimulation
prohibition of high level physical activity Long term B-blocker Defib implantation Possibly selective use of cardiac sympathetic denervation (ablation of stellate ganglion) |
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Tachycardia induced cardiomyopathy clinical presentation
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Shortness of breath
Pitting edema Decline in functional status Easier to sleep with head elevated Puse 160, RR 22, BP 102/54 Jugular venous pressure elevated Crackles S3 gallop, rhythm is irregularly irregular Severe left atrial enlargement |
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CHADS2 score factors
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HTN, Age>74, Diabetes, Stroke (2x points)
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Tachycardia induced cardiomyopathy
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Reversible left ventricular systolic dysfunction complicating tachyarrhythmias
LV contractility decline, ECM remodeling, LV chamber dilation, severity systolic impairment, tachycardia recurrence; late sudden cardiac death reported |
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Mech of Tachycardia induced cardiomyopathy
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unknown but may be d/t transformation of fibroblast penotype and decreased ventricular collagen concentration and cross linking
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Tx of Tachycardia induced cardiomyopathy
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External cardioversion
Amiodarone loading (orally) Warfarin dose and digoxin are both reduced (amiodarone may increase drug levels of both) Continue to f/u (lung tox, liver enzymes, thyroid function) |
