Early predictive indexes of head-up tilt table testing outcomes utilizing heart rate and arterial pressure changes

Orthostatic tolerance is difficult to predict in recurrent syncope patients

“…Earlier studies compared hemodynamic responses between syncope patients with a positive or negative head-up tilt test or between syncope patients and healthy control subjects. Some [11,21,26,38], but not all [2,10,12,30] previous studies reported a similar relationship between heart rate responses and susceptibility to syncope.…”

On the feasibility of tilt test outcome early prediction using ECG and pressure parameters

“…Both authors studied RR interval and HR fluctuations, and both based their methods on the differences or variability between successive NN [36] as (a) rMSSD being the square root of mean square of successive NN (in ms); (b) pNN50 being the percentage of total pairs of adjacent NN differing more than 50 ms. Other authors [6,[10][11][12][13] focused on simple measurements of HR and AP (SAP, DAP, and differential AP), such as average, maximum, or minimum for a certain segments definition.…”

“…In general, the increase of HR during the first minutes of the test has been suggested as a predictive parameter for positive TTT result [6]. Also, AP in patients with positive TTT has shown a trend toward significantly lower values at systolic phases, and larger systolic-diastolic differences [11]; and brain blood supply did not fluctuate during the TTT in patients with VS in some studies, though more recent ones showed changes when measured by Transcranial Doppler Ultrasounds. Some other potential risk factors for syncopal recurrence are the number and frequency of preceding syncope episodes, as well as nausea, dizziness, and diaphoresis (profusely sweating), as they were pointed out as predictive on the positive result of the TTT [25].…”

“…In addition, the patient may feel very uncomfortable when the presyncopal or syncopal symptoms are reproduced. These problems have motivated the search for methods allowing the early prediction of the TTT [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. The aim of these methods has often been to obtain a simple measurement, taken from an easily available cardiac signal (such as HR or pressure tachogram) at the beginning of the test, which would be used as a predictive criterion for the final result.…”

“…The use of AP for TTT outcome prediction was introduced in [11], combined with HR. In 178 patients, changes were more significant during the first 5 min in HR, systolic AP (SAP), and differential AP for patients with positive test outcome (diastolic AP-DAP-did not change significantly), providing a set of results ranges for different analysis: 68-55% specificity, and 53-72% sensitivity.…”