Cardiac Medications

1. Cardiac Medications C. Cummings RN, EdD

2. Cardiac Meds Cardiac Output = X Stroke Volume Heart Rate Afterload Preload Contractility Sympathetic Stimulation Meds PVR Venous Return Viscosity Ventricular Compliance Aortic Impedance

3. Preload • Function of the volume of blood to the LV and the compliance (ability of the ventricle to stretch) of the ventricles at the end of diastole (LVEDP) • Factors affecting are: venous return, total blood volume and atrial kick • Hypovolemic patient has too little preload • Heart failure patient has too much preload

4. Afterload • Ventricular wall tension or stress during systolic ejection • Increase in afterload relates to an increase in the work of the heart • Increased afterload R/T: • Aortic stenosis • Vasoconstriction and SVR • Blood volume and viscosity • To decrease, use vasodilators, decrease myocardial oxygen demand

5. Contractility • Inotrophy or enhancing strength, can be positive or negative • Sympathetic medications increase contractility • Ca++ is a medication that will increase contractility by increasing actin and myosin contractions • Digoxin also works to increase Ca++ channels by slowing the Na/Ca pump

6. Control of Heart Rate • SNS- sympathetic nervous system • Fight or flight • Increase HR, BP, respirations, dilate pupils • PNS- parasympathetic system • Decreases contractility, rate • Vagus nerves to the SA and AV nodes • Baroreceptors- pressure sensors in carotids and aortic arches • Chemoreceptors- pH levels in aortic arch • ANF- atrial natriuretic factor- hormone secreted by the atria in response to atrial pressure • Causes Na and water to be excreted and also vasodilates

7. Control of Stroke Volume • Preload • Increase use: • Fluid resusitation • Decrease use: • Diuretics and vasodilators • Afterload • Increase use: • Vasopressors • Volume expanders • Afterload • Decrease use: • Vasodilators • Diuretics • Decrease sympathetic stimulation • Contractility • Increase use: • Sympathetic stimulants • Decrease use: • CCB’s • Decrease sympathetics

8. Vasopressors • Sympathomimetic-inotrophic • Medications that mimic the sympathetic system, work on alpha, beta and dopamineric receptors • Require continuous monitoring of BP and heart rate • Alpha: vasoconstricts peripheral arterioles • Beta 1: Increased HR, contractility • Beta 2: Bronchodilation

9. Vasopressor • Dopamine • Stimulates alpha and beta receptors • In small doses (2-5 mcg/kg/min) produces renal vasodilation • Larger doses (max 20 mcg/kg/min) alpha and beta stimulation • Increases HR and BP • Precautions: • Give IV only, can sloughing of tissue with extravasation, if it does infiltrate, give phentolamine IV to the site • Tachyarrhythmias, palpations, hypotension if not hydrated, headache, dyspnea

10. Vasopressor • Epinephrine • Alpha-Adrenergic, beta 1 and beta 2 stimulant • Produces bronchodilation and vasoconstriction • Increases HR, BP and bronchodilates • Given IV, SQ and inhalation • Max is 20 mcg/min • Precautions: • Tachyarrhythmias • Angina • Nervousness, tremors • Hypertension • Works almost immediately IV • Watch for chest pain and HR >120, can cause cardiac arrest with too last a rate

11. Vasopressor • Norepinephrine • Stimulates alpha, beta receptors • Need to hydrate patient • Lacks beta 2 effects • Marked alpha vasoconstriction • Used in shock states • Max is 16 mcg/min • Precautions: • Closely monitor HR and BP, can elevate quickly • Monitor for peripheral vasoconstriction, in high doses, can constrict all extremities • Can decrease the C.O. if rate is too high

12. Vasopressor • Dobutamine • Synthetic cathecholamine with mainly beta effects • Mild stimulation of beta 2 • Increases myocardial contractility • Useful with heart failure patients • Max is 20 mcg/kg/min • Precautions: • Monitor for increased HR and BP • PVC’s and angina • Watch for shortness of breath • May be given over a long infusion for heart failure patients

13. Vasopressors- Phosphodiesterase Inhibitors • Cause increased levels of AMP and Ca++ • Medications: • Amrinone (Inocor) • Milrinone (Primacor) • Cause an increase in cardiac output and some decreased afterload • Effective in heart failure patients to increase C.O. • Precautions: • Given as a continuous IV infusion • Can cause PVC’s and V tach because of increased contraction • Monitor for drops in BP R/T decreased afterload • Watch for thrombocytopenia and abnormal liver function

14. Other Vasopressors • Phenylephrine (neo-synephrine) • Stimulates alpha receptors only • Used by anesthesia • Can increase myocardial demand • Works very quickly • Vasopressin (antidiuretic hormone) • Nonadrenergic peripheral vasoconstrictor • Used in VF and pulseless VT, 40Units • Used as an IV infusion in sepsis with peripheral vasodilation

15. Vasodilators- Direct Smooth Muscle Relaxants • Decrease PVR • Arterial and venous dilation • Improves cardiac output • Medications: • Nitroprusside (Nipride) • Nitroglyceride • Hydralazine (Apresoline) • Precautions: • Closely monitor BP, can drop dramatically, especially nipride • Long term nitroprusside therapy can lead to thiocyanate toxicity • NTG is used with unstable angina (given 5-300 mcg/min • Apresoline is not a continuous infusion, major side effect is tachycardia

16. Vasodilators- Ca++ Channel Blockers • Arterial vasodilation • Reduce the influx of calcium and decrease resistance • Used mostly for hypertension • Also to slow rapid rhythms, such as SVT, and Atrial fib • Medications: • Nicardipine (Cardene) • Nifedipine (Procardia) • Diltiazem (Cardizem) • Verapamil (Calan) • Side effects: • Hypotension, bradycardia, nausea, heart failure and peripheral edema

17. Vasodilators-ACE inhibitors • Vasodilate by blocking the conversion of angiotensin I to angiotensin II, decreases PVR • May drop BP dramatically if volume depleted • Stops Na and water retention • Medications: • Captopril (Capoten) • Enalapril (Vasotec) • Precautions: • Hypotension, chronic cough, neutropenia and elevated liver enzymes

18. Vasodilators- Alpha adrenergic blockers • Block peripheral alpha receptors in arteries and veins • Orthostatic changes may result • May lead to fluid retention • Medications: • Labetalol (normadyne) • Alpha & beta blocker • Decreased BP without increased HR • Used in aortic dissections • Phentolamine (Regitine) • Peripheral alpha blocker, decreases afterload • Used with pheochromocytomas

19. Vasodilators- DA-1 receptor agonists & Synthetic BNP • Dopamine DA-1 receptor agonists, vasodilates peripheral and renal arteries • Medication: • Fenoldopam (Corlapam) • Hypertensive emergencies • Watch for hypotension and tachycardia • Natrecor: • Brain naturietic peptide • Used for decompensated HR with dyspnea • Vasodilates pulmonary bed, reduces SVR and PVR • Lowers BNP levels • Infusion runs for 6-48 hours

20. Vaughn Williams Classification- Used for Antiarrhythmics • Class I agents interfere with the sodium (Na+) channel. • Class II agents are anti-sympathetic nervous system agents. Most agents in this class are beta blockers. • Class III agents affect potassium (K+) efflux. • Class IV agents affect calcium channels and the AV node. • Class V agents work by other or unknown mechanisms.

21. Class Ia • Medications: • Quinidine • Procainamide • Disopyramide • Type: • Na+ channel block intermediate • Use: • Ventricular arrhythmias • Prevents recurrent atrial fib, triggered by overactive vagal stimulation (Wolff-Parkinson-White syndrome) [edit] Class I agents

22. Class Ib • Medication: • Lidocaine • Phenytoin • Mexiletine • Type: • Na+ channel block fast • Use: • Ventricular tachycardia • Atrial fib • Prevention during and immediately after an MI, but it is now discouraged R/T increased risk of asystole

23. Class Ic • Medications: • Flecainide • Propafenone • Moricizine • Type: • Na+ channel block slow • Use: • Prevents paroxysmal atrial fib • Treats recurrent tachyarrhythmias of abnormal conduction system

24. Class II • Medications: • Propranolol • Esmolol • Timolol • Metoprolol • Atenolol • Type: • Beta Blocker • Use: • Decrease myocardial infarction mortality, used post MI • Prevent recurrence of tachyarrhythmias • Decrease Beta 1 and 2 stimulation, decrease HR and BP • Side effects of bradycardia, fatigue, wt. gain, impotence, depression

25. Class III • Medications: • Amiodarone • Sotalol (also a Beta) • Ibutilide • Dofetilide • Type: • K+ channel blocker • Use: • Ventricular tachyarrhythmias • Atrial flutter and atrial fib • Wolff-Parkinson-White syndrome • Side effects: • SOB, bronchospasm, renal or hepatic insufficiency • Photosensitive, use sunscreen and sunglasses, may cause bluing of periphery

26. Class IV • Medications: • Verapamil • Diltiazem • Type: • Ca++ channel blocker • Use: • Prevent recurrence of paroxysmal SVT • Reduce ventricular rate in patients with atrial fib • Decrease the contraction of muscle tissue, prevents slide of actin and myosin • Avoid grapefruit juice it can increase serum levels, as do high fat meals • Monitor thyroid function

27. Class V • Medications: • Adenosine • Digoxin • Type: • Work by other methods, direct nodal inhibition • Na/Ca pump • Use: • Supraventricular arrhythmias • Contraindicated in ventricular arrhythmias • Side effects: • Digoxin- bradycardia, anorexia, nausea & vomiting, yellow/green halos, heart blocks, arrhythmias, causes hypocalcemia and hypokalemia

28. Aspirin • Acts to reduce inflammation by inhibiting the production of prostaglandins • Decreases platelet aggregation, decreases the incidence of TIA’s and MI • Dosage of 81 mg maintenance, not enteric coated in MI • Monitor for GI bleeding, exfoliative dermatitis, Stevens-Johnson syndrome, tinnitus

29. Other Emergency Medications • Atropine: • Parasympathicolytic, enhances the SA node and AV node conduction • Used for bradycardia and asystole • Side effects: • Tachycardia, urinary retention, blurred vision, bowel obstruction, not for Complete heart block • Calcium Cl: • Enhances myocardial contractility for pts with elevated K, Mg and low Ca and CCB toxicity • Side effects: • Coronary and cerebral vasospasm, ventricular irritability, cautious if on Digoxin

30. Other Emergency Medications • Magnesium • Reduces post infarction arrhythmias and pump failure • Hypomagnesemia can cause refractory V fib and sudden cardiac death • Side effects: • Flushing, sweating, hypotension, sensation of heat, flaccid paralysis, circulatory collapse • Diprivan (Propofol) • Short acting sedative, used for sedation with patients who have airway and ventilatory support • Side effects: • Hypotension, rebound tachycardia and increased ICP when wean off, hepatotoxicity

31. Other Emergency Medications • Lorazepam (Ativan) • Benzodiazepine sedative • Effects last 6-8 hours • If given intraarterial can cause gangrene and limb loss • CNS depression is prominent if over 50 • Contraindicated if glaucoma • Watch for airway depression • Midazolam (Versed) • Benzodiazepine sedative • Effects last 1.5-2 hours • Depresses respiratory rate, apnea, can cause hypotension • Hiccups, headache, nausea, amnesia, confusion • Can be reserved with romazicon (flumazenil)

32. Other Emergency Medications • Succinylcholine • Neuromuscular blocking agent • Rapid acting agent for intubation • Side effects: • Hypotention, tachycardia, hyperkalemia, severe in neurologic patients myoglobinuria, malignant hyperthemia • Rocuronium or vecuronium • Neuromuscular blocking agent • Lasts 20-60 minutes • Can cause tachycardia, hypotension and bronchospasm in some patients, prolonged weakness if renal involvement