OBJECTIVE:The head-up tilt test has been used for more than 10 years to reproduce vagal lipothymia. The criteria for a positive test and specificity are however still lacking.METHOD:Thirty male volunteers, age 18 to 35 years, with no past history of lipothymia nor any signs of hypervagotonicity at physical examination, on fasting blood samples or on exercise tests with sudden interruption and Holter recording were selected for the study. Two head-up tilt tests at 60 degrees for 45 minutes were conducted, one with no presensitivisation and the other with a bolus of isoproterenol (2, 4, 6 and 8 micrograms) starting 30 minutes after the beginning of the test. Blood pressure was measured throughout the test.RESULTS:The systolic blood pressure curves showed drops of more than 30 mmHg accompanied by spontaneously resolving clinical signs in 6 of the 30 subjects during the non-sensitized tests and in 14 out of 30 during the sensitized tests. A symptomatic drop in systolic blood pressure of more than 30 mmHg compared to the moment before the malaise accompanied by clinical signs which did not resolve within 1 minute and required returning to the supine position occurred in one volunteer during a non-sensibilized test. This same type of reaction was observed in 4 volunteers during sensitized tests, three times after an isoproterenol bolus.CONCLUSION:Taking this later manifestation as the criteria for a positive head-up tilt test, the specificity of the non-sensitized and isoproterenol-sensitized tests in the young adult are 96.7 and 86.7% respectively. These findings must be considered with caution since there is no proof that these young men with no past history of hypervagotonicity but a positive head-up tilt test may be one day confronted with a situation generating a vagal reaction.

UNLABELLED:The presence of late potentials (LP) is considered as the evidence of an anatomical and electrophysiological condition which can give rise to life threatening ventricular arrhythmias. The aim of this work has been to study the incidence of LP in the setting of hypertension and to study their relation to ventricular hypertrophy on one hand and to ventricular arrhythmias on the other. Our study was conducted in 45 hypertensive patients (mean age +/- SD = 53 +/- 12). None of them had clinical evidences of a coronaropathy and only 5 had never been treated. For every patient we carried out a signal averaged electrocardiogram to detect LP, an echocardiogram to determine the myocardial mass index and 48 hours Holter monitoring to record ventricular arrhythmias filed according to the Lown classification.RESULTS:LP have been found in 13 patients. The following table summaries relations between LP, ventricular arrhythmias and myocardial hypertrophy: [table: see text]CONCLUSION:LP are frequently found in hypertensive patients (29%); their incidence is not higher in patients with left ventricular hypertrophy although they more frequently have serious ventricular arrhythmias; the severity of ventricular arrhythmias is not correlated with the presence of LP.