Medication Summary
No medication therapy is specific to LGL. The goals of therapy are to identify the cause of tachycardia and to treat this cause appropriately.
Beta-blockers
Class Summary
Inhibit chronotropic, inotropic, and vasodilatory responses to beta-adrenergic stimulation and slow AV nodal conduction.
Metoprolol (Lopressor, Toprol XL)
Selective beta1-adrenergic receptor blocker that decreases automaticity of contractions. During IV administration, carefully monitor BP, heart rate, and ECG.
Atenolol (Tenormin)
Selectively blocks beta1-receptors with little or no effect on beta2 types.
Calcium channel blockers (nondihydropyridine)
Class Summary
In specialized conducting and automatic cells in the heart, calcium is involved in the generation of the action potential. Calcium channel blockers inhibit movement of calcium ions across the cell membrane, depressing both impulse formation (automaticity) and conduction velocity.
Verapamil (Calan, Covera, Isoptin)
Can diminish PVCs associated with perfusion therapy and decrease risk of ventricular fibrillation and ventricular tachycardia. By interrupting reentry at AV node, can restore normal sinus rhythm in patients with PSVT.
Diltiazem (Cardizem)
During depolarization, inhibits calcium ions from entering slow channels and voltage-sensitive areas of vascular smooth muscle and myocardium.
Cardiac glycosides
Class Summary
Decrease AV nodal conduction, primarily by increasing vagal tone.
Digoxin (Lanoxin)
Cardiac glycoside with direct inotropic effects in addition to indirect effects on cardiovascular system. Acts directly on cardiac muscle, increasing myocardial systolic contractions. Indirect actions result in increased carotid sinus nerve activity and enhanced sympathetic withdrawal for any given increase in mean arterial pressure.
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Lown-Ganong-Levine Syndrome. Electrocardiogram demonstrating a short PR interval of approximately 100 ms and normal QRS.
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Lown-Ganong-Levine Syndrome. Electrocardiogram demonstrating ventricular preexcitation. A delta wave, which corresponds to initial myocardial depolarization via a bypass tract, appears at the beginning of each QRS complex.
