ACP Medicine

Atrial Fibrillation Part 1

Atrial fibrillation (AF) is a supraventricular tachyarrhythmia defined by rapid, irregular atrial activation. This disordered atrial activation results in loss of coordinated atrial contraction; irregular electrical input to the atrioventricular (AV) node typically leads to sporadic ventricular contractions. On an electrocardiogram, AF is characterized by the absence of visible discrete P waves, the presence of […]

Atrial Fibrillation Part 2

Restoration and maintenance of sinus rhythm Sinus rhythm can be restored with medication, electrical shocks, or a combination of both. Electrical shocks typically are more effective than medication for cardioversion and pose a lower risk of life-threatening ventricular arrhythmias. However, shocks require conscious sedation. In a proportion of patients refractory to medication or electrical shocks, […]

Atrial Fibrillation Part 3

Pharmacologic Approaches to Maintaining Sinus Rhythm Except for patients in whom the cause of AF is reversible, pharmacologic therapy likely will be required to maintain sinus rhythm after cardioversion. In approximately 50% of AF patients who undergo cardioversion to sinus rhythm, AF will return within 1 year if prophylactic drug therapy is not employed; AF […]

Supraventricular Tachycardia Part 1

Over the past decade, enormous strides have been made in the treatment of patients with supraventricular tachycardia (SVT). Although acute therapy for SVT continues to require drugs or cardioversion, advances in the understanding of the mechanisms of SVT have led to the development of catheter ablation procedures for most forms of SVT.1 These procedures often […]

Supraventricular Tachycardia Part 2

Long-term Therapy A wide variety of drugs have proved effective for controlling episodes of AVNRT, including beta blockers,9 calcium channel blockers,12 and digoxin13 [see Table 1]. Long-term drug therapy is associated with frequent recurrences and adverse effects, however. In patients without structural cardiac disease, class IC an-tiarrhythmic agents (e.g., flecainide, propafenone) are more effective than […]

Ventricular Arrhythmias Part 1

Ventricular tachyarrhythmias characteristically are sudden in onset, unpredictable, and transitory. Consequently, their assessment and treatment present extraordinary challenges to the clinician. Moreover, the prognosis for patients with these arrhythmias is quite variable. In some patients, ventricular ectopic activity may be benign and without sequelae, but in other patients, comparable ectopy is a harbinger of ventricular […]

Ventricular Arrhythmias Part 2

Signal-averaged electrocardiography Signal-averaged electrocardiography may be useful for estimating risk in patients with heart disease and ventricular ectopy. This noninvasive test detects signals from areas of slow conduction in the arrhythmogenic regions on the periphery of an MI. The surface ECG is recorded for approximately 250 beats, and the signal is averaged by a computer […]

Ventricular Arrhythmias Part 3

Proarrhythmia Proarrhythmia refers to the worsening of an existing arrhythmia or the induction of a new one by an antiarrhythmic drug. Three types of proarrhythmia have been described: torsade de pointes (the most common), incessant ventricular tachycardia, and extremely wide complex ventricular rhythm. Torsade de Pointes Torsade de pointes is triggered by early afterdepolarizations in […]

Pacemaker Therapy

Worldwide, more than 250,000 permanent cardiac pacemakers are implanted each year. As the population ages and as indications for pacemakers expand, the number of implants continues to increase. Advances in technology have played an important role in the evolution of pacemaker therapy: currently available pacemakers are smaller and more reliable than older models and contain […]

Acute Myocardial Infarction Part 1

Conduction abnormalities are common in the setting of acute myocardial infarction.11-15 Pathophysiologic mechanisms include ischemia, necrosis, autonomic influences, and the neurohumoral response to injury. Temporary transvenous pacing is often required during the acute phase of an infarction. The need for temporary pacing does not, however, predict the need for permanent pacing, given that many of […]

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