Supraventricular Arrhythmias: An Electrophysiology Primer

Carol Chen-Scarabelli, MSN, APRN, BC, CCRN

Disclosures

Prog Cardiovasc Nurs. 2005;20(1):24-31. 

In This Article

Epidemiology

The high incidence of atrial arrhythmias is mostly due to AF. However, sinus tachycardia, another atrial arrhythmia, is a common physiologic response to stressors such as pain, fever, exercise, or anxiety. Other arrhythmias arising from the atrium include multifocal AT, which is typically observed in elderly patients with pulmonary disease, and AFL, which is often associated with cardiomyopathy, hyperthyroidism, and electrolyte imbalance.[15]

As previously mentioned, AF is the most common arrhythmia and its prevalence increases with advancing age, with greater prevalence in patients over the age of 69 years.[16] More than 2.2 million people in the United States alone are affected by AF and have a 1.5-1.9-fold increase in the risk of death.[16] The incidence of new-onset AF doubles with each decade of age, independent of other risk factors.[17] In fact, it is predicted that the number of patients with AF will increase 2.5-fold by the year 2050, to affect over 5.6 million US adults.[6] There are distinct gender differences in mortality risk from AF, with a 1.5-fold increase for men, compared with a 1.9-fold increase for women.[18,19]

Risk factors for the development of AF include: hypertension (HTN), diabetes mellitus, male gender, congestive heart failure, and valvular disease, with HTN being the dominant risk factor.[17,20] In both men and women, HTN and diabetes were found to be significant independent predictors of AF, with HTN conferring a 1.5-fold risk in men and 1.4-fold risk in women while diabetes conferred a 1.4-fold risk in men and a 1.6-fold risk in women.[17] Risk assessment also includes left atrial diameter, left ventricular wall dimensions, and left ventricular systolic function.[17,20] Due to the risks, notably stroke, associated with this arrhythmia, there has been much focus on prevention and treatment of AF, which is responsible for 15%-25% of all cerebrovascular accidents in the United States alone.[16] Numerous clinical trials have documented no advantage of rhythm over rate control in the treatment of AF.[21,22] Risk factors for cerebrovascular accident due to AF include: male gender, rheumatic valve disease, congestive heart failure, HTN, diabetes, previous history of a cerebrovascular accident or transient ischemic attack, advanced age, global left ventricular dysfunction, coronary artery disease, mitral stenosis, or the presence of a prosthetic valve.[16]

This reentrant arrhythmia is more common in the elderly, with a greater prevalence in men than in women. It is associated with hypoxia, hyperthyroidism, cardiomyopathy, alcohol intake, electrolyte imbalance, and pheochromocytoma. Although two thirds of AFL patients have HTN or coronary artery disease, the remaining one third has no cardiac disease ( Table II ).[23]

This arrhythmia is fairly uncommon and is usually seen in elderly patients, predominantly men, with pulmonary disease. The distinguishing feature of this arrhythmia is the presence of three or more distinct P-wave morphologies.[24]

These arrhythmias occur less frequently than atrial arrhythmias and involve the AV node. The two most common types are AVNRT and AVRT.[15] AVNRT is more common in women than in men, and accounts for 50%-60% of narrow QRS atrioventricular tachyarrhythmias.[15,25] Both AVNRT and AVRT occur more commonly in younger patients, but unlike AVNRT, AVRT is more common in males (2:1 ratio) and it affects less than 0.5% of the population.[15] AVRT commonly presents at a younger age than AVNRT and is associated with Ebstein anomaly. However, most patients do not have evidence of structural heart disease. AVRT is the result of two or more conducting pathways (i.e., the AV node, and one or more bypass tracts).[15] Other less common AV arrhythmias include nonparoxysmal junctional tachycardia and junctional ectopic tachycardia. These rare arrhythmias are usually observed after vascular surgery, post-MI, in digoxin toxicity, and in children after congenital heart surgery.[15]

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