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Kusumoto et al 2018 Bradycardia Clinical Practice Guidelines Circulation. 2019;140:e382–e482. DOI: 10.1161/CIR.0000000000000628 August 20, 2019 e421 CLINICAL STATEMENTS AND GUIDELINES Recommendation-Specific Supportive Text 1. Atropine is a parasympatholytic drug that enhances atrioventricular nodal conduction and automaticity, generally given in 0.5- to 1.0-mg IV increments. Current advanced cardiac life support recommendations advise early use of atropine for medical treatment of hemodynamically significant bradycardia, including atrioventricular block. Uncontrolled cohort studies suggest efficacy and clinical benefit, particularly in the setting of acute inferior MI.S6.3.2-1–S6.3.2-3 Atropine is unlikely to improve atrioventricular block at the His bundle or His-Purkinje level and isolated reports have suggested occasional worsened atrioventricular conduction and/or hemodynamic compromise in such patients. For this reason, atropine should be used judiciously in patients with atrioventricular block and wide QRS complexes that suggest the presence of significant His Purkinje disease. Adverse effects of atropine include dry mouth, blurred vision, anhidrosis, urinary retention, and delirium. Excessive increase in heart rate may be problematic, particularly in patients with acute MI. 2. Beta-adrenergic agonists such as isoproterenol, dopamine, dobutamine, and epinephrine exert direct effects to enhance atrioventricular nodal and, to a lesser degree, His-Purkinje conduction. These drugs may also enhance automaticity of subsidiary atrioventricular junctional and ventricular pacemakers in the setting of complete atrioventricular block. Clinical efficacy of dopamine was shown to be equivalent to transcutaneous pacing in 1 small randomized trial of patients with unstable bradycardia unresponsive to atropine in the prehospital setting.S6.3.2-7 Isoproterenol was shown to elicit an escape rhythm in 68% of pacemaker-dependent patients undergoing generator replacement.S6.3.2-4 Other data come from cohort studies of limited design.S6.3.2-3,S6.3.2-5,S6.3.2-6 Adverse effects of beta-adrenergic agonists may include elicitation of ventricular arrhythmias and induction of coronary ischemia, particularly in the setting of acute MI or unstable coronary artery disease. In addition, isoproterenol may exacerbate hypotension because of the vasodilatory effects. 3. Aminophylline is a methylxanthine compound that is a nonselective adenosine receptor antagonist and phosphodiesterase inhibitor. It is used clinically as a bronchodilator and as a reversal drug for dipyridamole, adenosine, and regadenoson in pharmacologic nuclear stress testing. Experimental evidence suggests a role of increased adenosine production in development of atrioventricular block in acute inferior MI. Several small case series of up to 8 patients have shown prompt reversal of atrioventricular block in this clinical setting without adverse effects.S6.3.2-8–S6.3.2-11 Larger cohort studies and randomized trials in hospitalized patients are lacking. A large randomized trial and a systematic review showed no benefit for aminophylline in resuscitation for out-of-hospital brady-asystolic cardiac arrest.S6.3.2-12 6.3.3 Temporary Pacing for Atrioventricular Block Recommendations for Temporary Pacing for Bradycardia Attributable to Atrioventricular Block Referenced studies that support recommendations are summarized in Online Data Supplements 29 and 30. COR LOE Recommendations IIa B-NR 1. For patients with second-degree or third-degree atrioventricular block associated with symptoms or hemodynamic compromise that is refractory to medical therapy, temporary transvenous pacing is reasonable to increase heart rate and improve symptoms.S6.3.3-1–S6.3.3-7 IIa B-NR 2. For patients who require prolonged temporary transvenous pacing, it is reasonable to choose an externalized permanent active fixation lead over a standard passive fixation temporary pacing lead.S6.3.3-8–S6.3.3-14 IIb B-R 3. For patients with second-degree or third-degree atrioventricular block and hemodynamic compromise refractory to antibradycardic medical therapy, temporary transcutaneous pacing may be considered until a temporary transvenous or PPM is placed or the bradyarrhythmia resolves.S6.3.3-15–S6.3.3-20 Synopsis Temporary transvenous pacing techniques have been used for nearly 60 years but have remarkably little data to guide their appropriate use. Early literature suggests a high rate of complications and dislodgement that has prompted some authors to advise very limited use.S6.3.3- 2,S6.3.3-4 More recent case series and trials with balloon flotation catheters suggest better safety profile.S6.3.3-6 The cause of atrioventricular block must be taken into account when considering the timing and necessity of temporary pacing. For example, in the setting of an MI, initial focus on primary reperfusion rather than temporary pacing for rate support may be associated with improved outcomes.S6.3.3-21 The safety of prolonged temporary pacing with an externalized active fixation permanent pacing lead has been demonstrated over the past 10 years.S6.3.3-8–S6.3.3-14 Transcutaneous pacing, devised >60 years ago, has a limited role in the Downloaded from http://ahajournals.org by on October 7, 2026