Figure 6: Ventricular Pacing During Head-up Tilt Testing.

The heart rate and blood pressure measured with the patient supine and at the start of the head-up tilt test are shown in A and B, respectively. At 5 minutes (C), cardiac asystole ensued, lasting 10.5 seconds. After the patient was placed in the supine position again and heart rate and blood pressure were stabilised (D), the test was repeated during ventricular pacing (E). At 6.5 minutes (F), there was a significant decrease in arterial pressure and syncope occurred despite ventricular pacing at a rate of 80 BPM. A negative response to the tilt test was seen after 3 days of oral metoprolol therapy, as exemplified by the tracing at 15 minutes (G). Source: Sra et al., 1993.[25] Reprinted with permission from Massachusetts Medical Society.