04 Jan

Cardiac Arrhythmias during Theophylline Toxicity: Results (3)

The VPB number and complexity decreased as STC fell. A follow-up 24-hour ECG recording performed eight days after recovery from toxicity at a time when STCs were less than 20 mg/L demonstrated AF with a ventricular response rate of 70 to 90/min. Ventricular ectopic beats were rare and there were only two VPB couplets and no VPB runs or sustained VT noted during 24 hours of recording. Due to the delay associated with performing the STC assay, notifying an investigator, and obtaining informed consent (average, six hours from the time of blood sampling to ECG recorder activation), STC had peaked and was stable or declining in all patients by the time the recorder was activated. The frequency and complexity of ventricular ectopy during the initial hour of recording was examined as an indicator of ectopy during the remainder of toxicity. Of the seven patients who averaged more than ten VPBs per hour or had couplets or runs during toxicity, ventricular ectopy of similar frequency or complexity was noted during the first hour of recording in five patients. Two patients (patients 7 and 14) had relatively few VPBs during toxicity and during the initial hour of recording, but had a single brief (four to six beats) VPB run later in the course of toxicity. The single patient with ventricular ectopy requiring antiarrhythmic therapy (patient 12) had large numbers of VPB runs during the initial hour of recording. There was a similar duration of ECG recording during the “toxicity” phase (STC >20 mg/L) and the “recovery” phase (STC <20 mg/L) (Table 3). Heart rate was significantly slower during the recovery phase. Although all patients with VPBs continued to have ectopy, the number of VPBs per hour decreased significantly during recovery. levitra super active plus

Table 3—Selected Results of Continuous Electrocardiographic Monitoring for Hours When Estimated STC >20 mg/L vs STC <20 mg/L

Parameter Toxic (STC >20 mg/L) Recovery (STC <20 mg/L) Significance
Duration of recording, h 11 ±8 10 ±4 NSt
Heart rate, beats/m in 116 ± 14 104 ± 12 P<0.001t
Any VPB, patients 13 13 NS|
VPB couplets, patients 7 4 NSt
VPB runs, patients 4 2 NSt
SVE runs, patients 4 3 NSt
VPB/h 140 ±327 74 ± 148 p<0.05§

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