Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content +++ KEY FEATURES +++ ESSENTIALS OF DIAGNOSIS ++ Atrial rate of 150–250 bpm Atrioventricular (AV) block of 2:1 Often associated with digitalis toxicity +++ GENERAL CONSIDERATIONS ++ Increasingly seen in advanced organic heart disease and severe pulmonary disease Digoxin toxicity must be suspected A ventriculophasic response is often seen (P-P intervals containing QRS complexes are shorter than those that do not) May be secondary to automaticity or triggered activity Exacerbated by hypokalemia, particularly when associated with digoxin excess +++ CLINICAL PRESENTATION +++ SYMPTOMS AND SIGNS ++ Related underlying cardiac disease and ventricular rate Shortness of breath Rarely chest pain Palpitations Gastrointestinal symptoms secondary to digitalis toxicity +++ PHYSICAL EXAM FINDINGS ++ Varying S1 Disproportionate jugular a waves compared with pulse (2:1) Carotid sinus massage may slow pulse rate (not advised in digitalis toxicity owing to induction of serious ventricular arrhythmia) +++ DIFFERENTIAL DIAGNOSIS ++ Other forms of atrial tachycardia Atypical AV nodal reentrant tachycardia Atrial flutter +++ DIAGNOSTIC EVALUATION +++ LABORATORY TESTS ++ CBC, basic metabolic panel Serum digoxin level (may not correlate with toxicity, which is a clinical diagnosis) Arterial blood gas analysis if there is evidence of advanced lung disease +++ ELECTROCARDIOGRAPHY ++ Shows atrial tachycardia usually with 2:1 AV block The ventricular rate is often within the normal range Varying block may also be noted +++ IMAGING STUDIES ++ Echocardiogram to assess underlying heart disease +++ DIAGNOSTIC PROCEDURES ++ None required +++ TREATMENT +++ CARDIOLOGY REFERRAL ++ When secondary to digitalis toxicity usually can be managed by a generalist When tachycardia is persistent with advanced heart disease, cardiology referral is required +++ HOSPITALIZATION CRITERIA ++ Almost all patients require hospitalization secondary to advanced nature of underlying disease +++ MEDICATIONS ++ Withdraw digoxin when appropriate In life-threatening conditions, consider digoxin (Digibind) 228 mg (6 vials); life-threatening ingestions may require more Correct electrolyte abnormalities Therapies targeted at abolishing the arrhythmia are unrewarding In persistent cases, AV block with medication may be achieved to control ventricular rate +++ THERAPEUTIC PROCEDURES ++ If the tachycardia is secondary to advanced heart disease and not related to digitalis toxicity, then radiofrequency ablation may be attempted with a mapping (contact or noncontact) system +++ SURGERY ++ Usually not required +++ MONITORING ++ ECG monitoring in hospital Digoxin level monitoring during Digibind therapy +++ DIET AND ACTIVITY ++ Related to underlying heart ... GET ACCESS TO THIS RESOURCE Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. Access My Subscription GET ACCESS TO THIS RESOURCE Subscription Options Pay Per View Timed Access to all of AccessCardiology 24 Hour $34.95 (USD) Buy Now 48 Hour $54.95 (USD) Buy Now Best Value AccessCardiology Full Site: One-Year Individual Subscription $595 USD Buy Now View All Subscription Options