Sections View Full Chapter Figures Tables Videos Annotate 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 ... Your Access profile is currently affiliated with [InstitutionA] and is in the process of switching affiliations to [InstitutionB]. Please select how you would like to proceed. Keep the current affiliation with [InstitutionA] and continue with the Access profile sign in process Switch affiliation to [InstitutionB] and continue with the Access profile sign in process Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Error: Incorrect UserName or Password Username Error: Please enter User Name Password Error: Please enter Password Sign in Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free profile for additional features.