Rate control The first-line agents for rate control are beta-blockers and calcium channel blockers (CCBs) within the non-dihydropyridine class, such as diltiazem and verapamil. Non-dihydropyridine CCBs are prescribed over the dihydropyridine class since the non-dihydropyridine class have negative chronotropic (rate) effect and negative dromotropic effect (conduction velocity). When controlling the ventricular response of AF, beta-blockers and CCBs may be enough to convert AF back to normal sinus rhythm (NSR) since the SA node resumes its function as the pacemaker of the heart. Providers should use caution with beta- blockers and CCBs in decompensated heart failure since they have a negative inotrope action (negative force of contraction). Other agents such as digoxin can be used, although it is reserved for heart failure patients or those with hypotension who do not respond to beta blockers or CCBs (Chung et al., 2020; Frost et al., 2017; Hindricks & Potpara, 2020; Walsh & Caple, 2018). Prescribing implications for APRNs for medications utilized for rate control are related to the medication’s mechanism of action. Baseline 12 lead or continuous ECG monitoring is necessary to assess for bradycardia and various forms of heart block. A first-degree heart block would not warrant holding these medications. A first-degree heart block would be expected from the negative chronotropic and dromotropic mechanism of action. However, if the patient develops a second-degree or third-degree heart block, holding the medications, assessing for hemodynamic stability, and collaborating with cardiology would be the next course of action. In some instances, if a second- or third-degree heart block continues, the patient may benefit from transcutaneous pacing, temporary venous pacemaker, or permanent pacemaker. If invasive hemodynamics are being measured via a pulmonary artery catheter, it is expected that beta-blockers or negative inotropic drugs would be held to maintain a cardiac index of 2.0. Beta blockers, which are cardio-selective, are metoprolol (Lopressor, Toprol XL); atenolol (Tenormin); nebivolol (Bystolic), and esmolol (Brevibloc). Clinically, metoprolol and esmolol could be the agents of choice for acute onset AF, whereas other agents could be considered for persistent/chronic AF. The non- cardioselective beta blockers are carvedilol (Coreg), labetalol (Trandate), and the prototype beta blocker propranolol (Inderal). When using noncardioselective beta blockers, which block both beta 1 and beta 2 receptors, it is important to monitor for wheezing and avoid in patients with asthma. Many providers utilize carvedilol when AF occurs with patients with systolic heart failure as it has Beta 1, Beta2, and alpha blockade. The alpha blockade is advantageous in this patient population to reduce afterload or resistance in the weakened left ventricle. Titration of rate control medications can be more aggressive in the inpatient Rhythm control The conversation on determining which agents are utilized for rhythm control is more complex. The major question here focuses on whether the patient has structural heart disease. If a patient has no structural heart disease, dofetilide, flecainide, propafenone, sotalol, and amiodarone can be used. If the patient has structural heart disease with coronary artery disease, the agents that can be utilized are dofetilide, dronedarone, sotalol, and amiodarone (Chung et al., 2020; Frost et al., 2017; Walsh & Caple, 2018). With a patient in heart failure, the choices are limited to amiodarone and dofetilide. The reasoning behind which agents to use in the cases where structural heart disease is present and, specifically with heart failure, is based on their arrhythmic potential as related to the prolongation of the QT interval. Amiodarone rarely causes torsades de pointes, with an incidence of less than 1% (Giardina & Zimetbaum, 2018). In addition, despite seeing a prolongation of the QT interval (500 ms), the incidence of the prolonged QT interval associated with
setting where continuous monitoring is available. Intravenous administration can be utilized initially and then converted to oral dosages (Chung et al., 2020; Frost et al., 2017; Hindricks & Potpara, 2020; Walsh & Caple, 2018). Patients should be educated on how to monitor their pulse and blood pressure. Ideally, education should be done with the family or significant others using the teach-back method. Rising slowly from a supine position to prevent orthostatic hypotension is prudent, especially for the elderly. Diabetic patients should be educated on the risk of hypoglycemia with vigilance in monitoring. As with any medication, patients should be educated to never abruptly stop beta blockers second to the rebound tachycardia. As noted previously, digoxin, can be used for rate control, yet it is reserved for systolic heart failure patients or those with hypotension who do not respond to or have contraindications to beta blocker and calcium channel blocker administration. There are several important considerations with digoxin. First, digoxin and potassium compete with each other to bind to Na-K-ATPase. If potassium levels are low, digoxin has increased binding, which increases digoxin serum levels and resultant digoxin toxicity. Assuring a normal potassium level is essential in care. Secondly, digoxin has a narrow therapeutic index. The recommended serum levels are between 0.8 to 2 ng/mL. Signs and symptoms of digoxin toxicity are anorexia, nausea, vomiting, changes in vision (halo vision, yellow or green-tinted vision), and bradycardia. If digoxin levels are dangerously high, the antidote, digoxin immune fab (digibind), can be administered. Thirdly, the kidneys excrete approximately 70% of digoxin in direct proportion to the patient’s glomerular filtration rate, hence those with acute kidney injury or chronic kidney disease should be monitored closely for toxicity. Another prescribing consideration with digoxin is it has a variable rate of absorption between brands, so patients should not switch between brands (David & Shetty, 2021; Hindricks & Potpara, 2020). Nursing consideration: In review, beta blockers and non- dihydropyridine class CCBs are used for rate control as first- line agents. The use of cardioselective agents can be utilized in patients with pulmonary disease. Cardizem is the most prescribed non-dihydropyridine class CCB over verapamil. Clinically, providers will avoid both beta blockers and CCB in decompensated heart failure. Here, digoxin may be the drug of choice second to its positive inotropic effect. The practice guidelines recommend starting one agent and titrating the drug to the desired dose/effect as long as long as the patient does not experience undesired adverse effects. Adding on a second agent may be necessary to maximize the negative chronotropic and dromotropic effect. ventricular arrhythmias is low (Chung et al., 2020; Frost et al., 2017; Walsh & Caple, 2018). Amiodarone is classified as a Class III antiarrhythmic primarily affecting phase III of the action potential by blocking potassium rectifier currents. Unlike other class III agents, amiodarone also blocks beta-adrenergic receptors, calcium channels, and sodium channels, hence it works on more than one phase of the action potential. It has the ability to decrease SA node automaticity, AV node conduction velocity, and inhibit ectopic pacemaker automaticity, all of which are effective in terminating AF (Florek & Girzadas, 2021). First, the pharmacokinetic and dynamic profile of amiodarone will be discussed. A unique feature of amiodarone is that it is a highly lipid-soluble medication and takes many days to reach a steady state after IV loading or oral loading doses are given. As it is taken up and stored in adipose tissues such as the muscles, liver, lungs, and skin, it results in a large volume of distribution. Because of this large volume of distribution and high protein
Page 62
Book Code: AUS3024
EliteLearning.com/Nursing
Powered by FlippingBook