Negative GTN Tilt Table Test
20 minutes into the test both systolic blood pressure and heart rate are steady. Following 400 mcg of sublingual GTN the heart rate rose swiftly from 80 beats per minute to 140 beats per minute while the systolic blood pressure fell from 80 mmHg to 30 mmHg at the point of syncope.
The test is negative because there was insignificant (<20%) drop in heart rate following profound GTN induced hypotension.
On lying the patient flat the blood pressure swiftly recovered and the heart rate returned to normal.