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- Calcium Channel Blocker
- Class IV antidysrhythmic
Mechanism of Action:
- Diltiazem inhibits the influx of extracellular calcium across both the myocardial and vascular smooth muscle cell membranes. Resulting in dilation of the coronary and systemic arteries; improved oxygen delivery to the myocardial tissue; and decreased total peripheral resistance, systemic blood pressure, and afterload.
- It is a negative dromotrope & creates refractoriness in the AV node. Its effects on calcium channels in SA and AV nodes, and peripheral vasculature are equipotent.
- Atrial fibrillation & atrial flutter with a rapid ventricular response
- Multifocal atrial tachycardia
- 2nd or 3rd degree AV block (in the absence of a functioning pacemaker)
- Sick Sinus Syndrome (in the absence of a functioning pacemaker)
- Cardiogenic shock
- Atrial fibrillation or atrial flutter associated with WPW or short PR syndrome (Lown-Ganong-Levine Syndrome)
- Ventricular tachycardia
- Wide-complex tachycardia of unknown origin
- AMI (associated with CHF or left ventricular dysfunction)
- Advanced aortic stenosis
- Hypotension (less than 90 mmHg)
- Renal / Hepatic Impairment
- Pregnancy (C)
DOSE: IV: 10 mg slow over 2 minutes. Repeat every 10-15 minutes PRN rate control. MAX 40 mg.
- Rarely required, doses are the same as adult.
- (Medical Control Order) 0.25 mg/kg IV over 2 minutes (Usual dose about 20 mg). May repeat in 15 minutes @ 0.35 mg/kg IV over 2 minutes
- First or second degree AV block
- Ventricular dysrhythmias
- CHF, Edema
- Hypotension, Syncope
- Chest pain
- May prolong the sedative effects of midazolam.
- May enhance the effects of ASA and prolong bleeding time.
- Additive effects with antihypertensives, alpha-blockers, & diuretics.
- Should not be used in combination with IV beta-blockers. The negative inotropic, chronotropic, & hypotensive effects can induce heart failure.
- Calcium salts can antagonize the hypotensive effects, but do not seem to have an effect on AV conduction.
- Incompatible with simultaneous furosemide injection.
- As always, unstable tachycardias with serious signs or symptoms warrant cardioversion.
- Hypotension may result and warrants careful monitoring of vital signs.
- PVCs may be present on conversion of PSVT to sinus rhythm.
- Medical Control may order (occasionally, physician preference) a pretreatment of calcium chloride for hypotensive or borderline hypotensive patients.
- Infusions are often not required prehospital with abbreviated transport times. Bolus Diltiazem has (in some studies) been shown to maintain therapeutic levels for 24-48 hours.
- AHA dosing for adults: 0.25 mg/kg IV over 2 minutes (Usual dose about 20 mg). May repeat in 10-15 minutes @ 0.35 mg/kg IV over 2 minutes .