This study will test the effect of diltiazem, a calcium channel blocking drug, on the QT interval in patients with Jervell and Lange-Nielsen syndrome. This will be a single IV dose and acute effects (within minutes) will be observed.
Subjects will be recruited by study personnel and will be scheduled for a single outpatient visit. If an implanted cardiac device (pacemaker or ICD) is in place, it will be interrogated to ensure no recent rhythm abnormalities. Just prior to administering diltiazem, an ECG and BP will be obtained. If baseline SBP is \< 100 mm Hg or DBP \< 60 mm Hg, the study will be terminated. A single dose of I.V. diltiazem (0.25 mg/kg over 2 minutes) will be administered with 12-lead ECG and BP obtained at 2, 5, 7, 10, 15 and 20 minutes. If at 10 minutes there has been no QT shortening, and the SBP is stable (\<20% drop from baseline and \> 100 mm Hg) a repeat dose (0.35 mg/kg) will be given at 15 minutes, with 12-lead ECG and BP obtained at 17, 20, 22, 25, 30 and 35 minutes. After 20 minutes (single dose) or 35 minutes (2 doses), the test will end and the subject will remain on continuous telemetry for 2 hours. Prior to discharge the IV will be removed. The primary analysis will be a repeated measures (paired) comparison of the QTc at baseline and following diltiazem.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
1
IV diltiazem (0.25 mg/kg) will be given over 2 minutes, with ECG and blood pressure measurements at baseline, 2, 5, 7, 10, 15 and 20 minutes. If at 10 minutes there is no QT shortening, and blood pressure is stable, an additional dose (0.35 mg/kg) will be given with ECG and blood pressure measurements at 17, 20, 22, 25, 30 and 35 minutes.
Vanderbilt University Medical Center
Nashville, Tennessee, United States
QT Interval
QT interval (on 12-lead ECG) in ms
Time frame: Baseline
QT Interval
QT interval (on 12-lead ECG) in ms
Time frame: 5 minutes
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