Diego I. Vanegas-Cadavid, Departamento de Cardiología/Electrofisiología, Fundarritmia – Fundación Cardiovascular, Bogotá, Colombia
Andrés F. Blanco-Ruiz, Departamento de Cardiología/Electrofisiología, Fundarritmia – Fundación Cardiovascular, Bogotá, Colombia
Introduction: The head-up tilt table test (HUTT) is widely used to reproduce reflex syncope (RS), but conventional monitoring based on intermittent blood pressure (BP) measurements and on-demand electrocardiograms (ECGs) may miss key hemodynamic sequences. Peripheral arterial tonometry (PAT) provides continuous, non-invasive pulse waveform monitoring and may offer complementary physiological information during syncope. Objective: to describe the feasibility of integrating PAT monitoring into a standard HUTT protocol and to characterize the autonomic response patterns observed using this approach. Methods: This was a prospective, single center, descriptive, observational physiological feasibility study including 41 consecutive patients undergoing a standard HUTT protocol between June and August 2022. Peripheral arterial tonometry (Watch- PAT®) was used exclusively as an adjunct continuous recording method. Outcomes were classified according to VASIS criteria. Continuous variables are reported as medians (IQR) and categorical variables as n (%). Results: The median age was 31 years (IQR 16–37), 58.5% were female, and the median BMI was 23.8 kg/m² (IQR 20.4–26.0). Syncope was reproduced in 19/41 patients (46.3%). The most frequent pattern was VASIS type III (vasodepressor; 10/41, 24.4%), followed by type I (mixed; 7/41, 17.1%) and type II (cardioinhibitory; 1/41, 2.4%); one patient met the criteria for POTS (2.4%). Isosorbide dinitrate was administered in 48.8% of cases. Continuous PAT allowed uninterrupted documentation of pulse waveform dynamics during orthostatism, capturing critical phases when intermittent BP measurements were delayed or unavailable. Conclusions: Continuous PAT monitoring during standard HUTT is feasible and may provide complementary physiological information for the characterization of autonomic response patterns, without replacing continuous hemodynamic reference methods or implying formal diagnostic validation.
Keywords: Head-up tilt table test. Peripheral arterial tonometry. Photoplethysmography. Reflex syncope. Vasovagal syncope. Postural orthostatic tachycardia syndrome.
