Head-up tilt testing with isoproterenol infusion caused no symptoms in healthy volunteers, whereas passive head-up tilt alone induced symptoms in 12% of subjects.
Cross-Sectional (n=25)
Does age affect the physiological and symptomatic response to head-up tilt testing with and without isoproterenol in healthy subjects?
Physiological responses to head-up tilt testing vary significantly by age, indicating that tilt testing protocols must be assessed against age-matched controls.
Absolute Event Rate: 0% vs 12%
Passive head‐up tilt testing with or without infusion of isoproterenol is used in the investigation and management of patients with syncope. Twenty‐five healthy asymptomatic volunteers prospectively grouped according to age (young 28 ± 1.7 years: n = 9; middle 51 ± 3.3 years: n = 11; elderly 81 ± 2.4 years; n = 5; mean ± SE) were studied during: (1) supine carotid sinus massage: (2) 60° head‐up tilt aione; and (3) infusion of isoproterenoJ to raise the heart rate 20% above supine baseline, prior to a 10‐minute repeat tilt. Symptoms occurred in three subjects (12%) and only occurred with passive tilting alone. Two young subjects had syncope with sinus pauses greater than 10 seconds, One elderly subject developed atrial flutter. No subject had symptoms or hypotension during tilt plus isoproterenol or a pause greater than 3 seconds with carotid sinus massage. With passive tilt, mean heart rate increased by 16 ± 6 beats/min and 18 ± 7.8 beats/min in the young and middle aged subjects (P < 0.05), but only by 6 ± 5 beats/min in the elderly (P = NS, supine vs 60° in each group). With head‐up tilt plus isoproterenol infusion, the mean heart rate elevation in response to tilt was 17 ± 9 beats/ min, 8 ± 3 beats/min, and 12 ± 4 beats/min for the young, middle, and elderly subjects, respectively (P < 0.05, supine vs 60° in each group). Supine serum norepinephrine concentration values were 229 ± 33 pg/mL, 374 ± 107 pg/mL, and 409 ± 41 pg/mL (mean ± SE) in the young, middle aged, and elderly groups, respectively (P = 0.05, young vs elderly). With head‐up tilt, these significantly rose in the three groups. With tilt, serum epinephrine tended to rise (P < 0.10) only in the young and middle aged groups. Serum dopamine did not significantly increase in response to tilt in any of the groups. These studies suggest that tilt testing protocols need to be assessed against age and protocol matched controls.
Newman et al. (Thu,) conducted a cross-sectional in Healthy asymptomatic volunteers (n=25). Head-up tilt testing with isoproterenol infusion vs. Passive head-up tilt alone was evaluated on Occurrence of symptoms. Head-up tilt testing with isoproterenol infusion caused no symptoms in healthy volunteers, whereas passive head-up tilt alone induced symptoms in 12% of subjects.
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