Intravenous theophylline--an alternative to temporary pacing in the management of bradycardia secondary to AV nodal block.

OBJECTIVE: To report a case of bradycardia secondary to atrioventricular nodal block (AVNB) successfully treated with intravenous theophylline. Intravenous theophylline was used as an alternative to temporary pacing in a patient with sepsis secondary to thermal injury. CASE SUMMARY: A 79-year-old white woman with significant cardiac history was admitted with 14.5% total body surface area burns after a house fire. Cardiac events included intermittent episodes of sinus bradycardia complicated by the development of second-degree AVNB and periods of sinus arrest. Intravenous theophylline initiation maintained normal sinus rhythm without further episodes of sinus bradycardia or heart block, thus preventing the need for cardiac pacemaker placement. DISCUSSION: This is the first case published in the English-language literature describing the use of intravenous theophylline as an alternative therapy to temporary pacing in a patient with sepsis secondary to thermal injury. Bradyarrhythmic events in sepsis patients have been associated with catecholamine production increasing adenosine formation. High concentrations of adenosine in the areas of the sinoatrial or atrioventricular nodal regions may induce sinus bradycardia or AVNB. Theophylline, an adenosine antagonist, has been identified as a treatment option for such bradyarrhythmic events. CONCLUSIONS: Theophylline, a methylxanthine derivative, may represent an alternative to other pharmacologic therapies and temporary pacing in the treatment of bradycardia secondary to AVNB. These agents may represent a pharmacologic alternative in patients in whom other pharmacologic strategies or cardiac pacemaker insertion may be contraindicated.

Predictive performance study of two digoxin assays in subjects with various degrees of renal function.

This prospective study was conducted to compare the predictive performance of fluorescence polarization immunoassay (FPIA, Abbott TDx Digoxin II) and radioimmunoassay (RIA, Kallestad Labs) with combined low-pressure liquid chromatography/RIA (LPLC/RIA) digoxin assay in measuring 15-17 serum digoxin concentrations (SDC) obtained after a single 10 microg/kg intravenous digoxin dose in patients with various degrees of renal function and at different SDC ranges. Eighteen men and women were stratified into 3 age- and gender-matched groups based upon renal function [N = 6 in each, group I (Cl(cr) < 10 mL/min), group II (Cl(cr) = 10-50 mL/min), and group III (Cl(cr) > 50 mL/min)]. Serum digoxin concentrations were measured at time zero; at 0.25, 0.5, 0.75, 1, 2, 3, 4, 6, 8, and 12 hours; and at 2, 3, 4, and 5-7 days after the digoxin dose, using the three different digoxin assays. TDx Digoxin II was unbiased [mean error -0.09 (95% CI -0.19, 0.01)] and RIA biased [mean error -0.29 (95% CI -0.36, -0.21)] to over-predict SDC by 14.2%. In group I patients, the analysis revealed a bias to over-predict SDC by 6.0% for TDx Digoxin II [mean error -0.16 (95% CI -0.29, -0.07)] and an unbiased performance by RIA. In groups II and III, both TDx Digoxin II and RIA showed biased performance, the mean magnitude of bias was low (< 20%). For intermediate SDC range (> 0.5 ng/mL and < or = 3.0 ng/mL), TDx Digoxin II was unbiased in predicting SDC, whereas RIA was biased to under-predict SDC [mean error 0.13 (95% CI 0.10, 0.16)] by 9.9%. The magnitude of bias observed in all cases was less than 20%. Both assays, TDx Digoxin II and RIA, imprecisely measured SDC for all samples combined, different groups and SDC ranges. In all time-paired samples, TDx Digoxin II (FPIA) performed better than the RIA. In conclusion, the magnitude of bias observed with either assay at different groups and SDC ranges was not likely to be clinically relevant. Therefore, either assay may be used to measure SDC in clinical practice.