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Cardiac Medications. Calcium Channel Blockers, Nitrates & Beta Blockers. Calcium Channel Blockers. Verapamil (Calan, Isoptin) Nifedipine (Procardia) Diltiazem (Cardizem) Amlodipine (Norvasc) Bepridil (Vascor) Felodipine (Plendil). Isradipine (DynaCirc) Mibefradil (Posicor)
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Cardiac Medications Calcium Channel Blockers, Nitrates & Beta Blockers
Calcium Channel Blockers • Verapamil (Calan, Isoptin) • Nifedipine (Procardia) • Diltiazem (Cardizem) • Amlodipine (Norvasc) • Bepridil (Vascor) • Felodipine (Plendil)
Isradipine (DynaCirc) • Mibefradil (Posicor) • Nicardipine (Cardene) • Nimodipine (Nimotop) • Nisoldipine (Sular)
Uses • Angina Pectoris • Hypertension • Treatment of SVTD’s • Atrial Flutter • Atrial Fibrillation • PSVT
Mechanisms of Action • Increase the time that calcium channels are closed • Relaxation of arterial smooth muscle but not a great deal on venous smooth muscle - significant afterload effects - little preload effects
Slows or inhibits the SA and AV node discharge • Slows atrioventricular conduction thus inhibits SVTD’s • Reduces inotropy in the heart • Reduced wall tensions and lower MVO2 demands
Lowers blood pressure due to arterial smooth muscle relaxation • Increases AV capture time - prolongs the refractory period of the AV node - thus, there is a negative chronotropic effect • Reduced vasospasms of epicardial vessels - reduces Prinzmetal angina
Side Effects • Bradycardia • Hypotension, Fainting & Syncope • Angina • Sedation • Flushing
Some Concerns….. • Recent evidence in the literature indicates that nifedipine may have arrhythmigenic capabilities
Nitrates • Nitroglycerin (Niong, Nitrobid)
Uses Of Nitroglycerin • Treat all forms of angina pectoris usually on an acute basis rather than a prophylactic basis
Mechanisms of Action • Vasodilate both arterial and venous smooth muscle resulting in reduced preload and afterload • Reduces end-diastolic filling pressures
Increases blood flow to the endocardial plexus by dilating the epicardials • Lowers MVO2
Side Effects • Fatigue & Orthostatic hypotension • Syncope • Headaches • Nausea • Vomiting
Beta Blockers • Propranolol (Inderal) non-selective • Atenolol (Tenorman) beta-1 selective • Pindolol (Visken) non-selective • Timolol (Blocarden) non-selective • Nadolol (Corgard) non-selective
Labetalol (Trandate) non-selective • Metaprolol (Lopressor) beta-1 selective • Carvedilol (Coreg) non-selective • …and many more
Beta adrenergic receptors : • beta-1 stimulate heart rate increases & increases contractile force • beta-2 stimulate bronchodilation and vasodilatation
Beta Adrenergic Blockade Causes……. • Lowering of the BP • inhibit norepinephrine release • inhibit vasoconstriction by catecholamines
Reduction of Cardiac Output • slows electrical conduction velocity • reduces sympathetic tone over the heart
Inhibition of Renin Release by the Kidneys • prevents renin from causing angiotensin I to transform to angiotensin II which acts as a potent vasoconstrictor • thus we have permissive vasodilatation
Reduced MVO2 • Reduction of angina • After-load is reduced • Longer diastolic filling times resulting in increased heart perfusion
Inhibits atrial and ventricular ectopies • Beta-blockers are cardioprotective
Medical Uses • Treatment of : • angina • hypertension • atrial & ventricular dysrhythmias • panic attacks • migraine headaches • reduces the incidence of esophageal bleeding due to varices
Side Effects • Bronchoconstriction - due to non-selective beta-blockade of beta-2 receptors • Inhibition of liver glycogenolysis