Conventional Treatment Strategies
Several strategies are available for treating arrhythmias, and the approach varies depending on the type of arrhythmia. For bradycardia, or slow heart rate, a pacemaker can be implanted to help ensure the heart beats quickly enough. Tacchycardias (fast heart rate) and fibrillations (irregular heart rate) can be treated with medications to slow the heart rate. A procedure called cardioversion uses electrical current, either synchronized or unsynchronized (defibrillation) with the cardiac cycle, to treat abnormally fast heart rate (tachyarrhythmia) or uncoordinated & irregular electrical activity in the heart (fibrillation). Another treatment option involves ablation of portions of heart tissue from which improper electrical signals are originating. In addition, since atrial fibrillation increases ischemic stroke risk, anticoagulant medications such as warfarin (Coumadin®) or dabigatran (Pradaxa®) are used to prevent blood clot formation in people with this arrhythmia (Gallego 2012; Ho 2012; MayoClinic 2011a).
This section will outline several arrhythmia treatment considerations:
It may be possible to stop an arrhythmia that begins above the ventricles by using vagal maneuvers that affect the vagus nerve, which is a part of the nervous system responsible for controlling the heartbeats. Some examples of these maneuvers, which often cause the heart rate to slow, include holding your breath and straining (Valsalva maneuver), dunking your face in icy water, and coughing; a physician may be able to recommend other maneuvers to slow down a fast heartbeat (NHLBI 2011b).
Arrhythmias can be treated with a variety of medications. The type of arrhythmia present and the unique characteristics of each patient determine which type of drug should be used and how. Because the clinical assessment of arrhythmias and the algorithm that physicians employ to determine the best pharmacologic treatment strategy is complex, this protocol will not discuss all of the specific roles of drugs in the various types of arrhythmias. Rather, we will outline the basic classification of drugs that may be utilized as part of pharmacologic arrhythmia management. Individuals with any type of arrhythmia should consult with a physician experienced in arrhythmia management to be properly evaluated and treated.
A classification method called the Vaughan-Williams system is widely used to categorize antiarrhythmic agents based on their effects on the electrophysiological system of the heart. This classification system characterizes antiarrhythmic drugs as follows (Weirich 2000; Ganjehei 2011; Homoud 2008):
Class I agents: Sodium-Channel Blockers. Class I antiarrhythmic agents are further subclassified as class IA, IB, or IC agents depending on how strongly they block sodium channels. Examples of class I agents include procainamide (Procanbid®), disopyramide (Norpace®), and flecainide (Tambocor®).
Class II agents: Beta-Adrenergic Blockers or “Beta-Blockers”. Some common beta-blockers are carvedilol (Coreg®), metoprolol (Lopressor®), and propranolol (Inderal®).
Class III agents: Potassium-Channel Blockers. Drugs in this class include sotalol (Betapace®), dofetilide (Tikosyn®), and ibutilide (Corvert®).
Class IV agents: Calcium Channel Blockers. A few common drugs that fall into this category include amlodipine (Norvasc®), diltiazem (Cardizem®), verapamil (Calan®).
Other agents: There are several antiarrhythmic drugs whose mechanisms are complex and/or not fully understood; they are usually grouped into this category. One frequently used drug that falls into this category is digoxin (Campbell 2001).
It should be noted that the Vaughan-Williams System has some considerable limitations because some drugs – such as amiodarone (which is typically considered a class III agent) for example – exhibit actions characteristic of more than one Vaughan-Williams class (Schmidt 2011). Therefore, physicians cannot rely solely on classification of antiarrhythmic agents in this manner when determining the best drug strategy for each patient.
In some cases of arrhythmia, cardioversion (ie, the process of delivering an external electrical jolt through the chest to the heart) may be utilized to reset the heart to its normal rhythm. The machine used to deliver the electrical current is called a defibrillator (Hebbar 2002a; Shea 2008; Sucu 2009).
Another technique often employed to treat arrhythmias is catheter ablation. This procedure involves the insertion of a thin wire catheter into a blood vessel in the groin, arm, or neck, which is then guided to the heart. Radiofrequency energy is then delivered through the wire to generate heat and destroy (ablate) small sections of tissue in the heart responsible for triggering the arrhythmia (Davoudi 2012). Other ablation techniques include application of extreme cold (ie, “cryoablation”) or high frequency ultrasound through the catheter to destroy the arrhythmogenic tissue (Narayan 2012; Joseph 2012).
Treatment for heart arrhythmias may also involve the use of an implantable device. Several types of such devices are currently available.
A pacemaker is an implantable, battery-operated device that is used in cases of slow or irregular heart rate. Implanting a pacemaker involves surgically placing the device under the skin, near the collarbone. An insulated wire connects the device to the right side of the heart, where it is permanently anchored. In cases of slow or abnormal heart rhythms, the device emits an electrical signal that stimulates the heart to beat at a normal rate. The device typically remains in a “switched off” mode when the heartbeat is normal (NHLBI 2011a; ExitCare 2012).
In ventricular fibrillation, which is a potentially life-threatening disorder, an implantable cardioverter-defibrillator (ICD) may be placed near the left collarbone, similarly to a pacemaker. The ICD does not turn off and monitors heart beats continuously. It acts as a pacemaker in cases of bradycardia and sends high-energy electrical impulses to reset the heart in cases of ventricular fibrillation or tachycardia (Estes 2011; Vlay 2009; NHLBI 2011a).
In some cases, surgery may be the recommended treatment for heart arrhythmias.
This procedure involves making surgical incisions in the atria, which heal into carefully placed scars that force cardiac electrical impulses to travel along a preset pathway and cause the heart to beat efficiently. The resulting scars form boundaries and create a ‘maze’ for electrical impulse to travel along. Rather than using a scalpel, scars can be created by using a ‘cryoprobe’ to apply extreme cold or a radiofrequency device that applies heat. Since this procedure requires open-heart surgery, it is typically reserved for patients who do not respond to other types of treatment (Nakamura 2012; MayoClinic 2011a).
Coronary Bypass Surgery
Coronary bypass surgery or coronary artery bypass graft (CABG) is performed in cases of severe coronary artery disease with frequent ventricular tachycardia. This procedure may help improve the blood supply to the heart and reduce the frequency of ventricular tachycardia (MayoClinic 2011a).