Role of Age on Cardiac Autonomic Profile in Patients With Neurally Mediated Syncope and Positive Response to Head Up Tilt Test
Bibliographic record
Abstract
The pathophysiology of neurally mediated syncope (NMS) remains controversial. Age related cardiac autonomic function in patients with NMS has not been systematically assessed. To determine the characteristics of age related non-invasive cardiac autonomic function in patients with NMS 1336 subjects with clinical diagnosis of NMS were assessed in the autonomic physiology laboratory at Fundacion Cardiovascular de Colombia. 815 patients had positive response to 70° head-up tilt test (HUT) standard to either a nitroglycerine or low-dose isoproternol protocols. Patients were divided in three study groups for comparison according to age: A = < 30 years (mean age 17±5); B = 31 to 65 years (48±9) and C = >66 years old (74±5). Non-invasive beat-to-beat (Finapress monitoring) heart rate (HR, bpm) and mean arterial blood pressure (MAP, mmhg) as well as short-term heart rate variability (HRV) and baroreflex gain (BRS, mmhg/msec) were measured using power spectral analysis and coherence and phase techniques respectively during supine 5 minutes (min) rest and during 5 min of 70°orthostatic stress (OS). HRV indexes, low-frequency (LF, normalized units: nu) and high-frequency (HF, nu) bands were obtained, and the LF/HF ratio was also calculated. In addition, cardiovagal function was assessed using 6 cycles per minute deep breathing test protocol (deep breathing difference DBD, bpm). One-way ANOVA and Student's t test were applied (significance test: p<0.05) Variables are shown as means ± SD. Significantly higher DBD was found in group A compared to groups B and C (20±8 vs. 14±8 and 20±8 vs. 15±11 respectively). HRV and BRS results are presented in the table above: Patients with NMS have characteristic age-related cardiac autonomic responses. Younger NMS patients have an increased chronotropic activity at rest and OS and a decreased vascular reactivity. Higher sympathovagal balance and progressive decrease in cardiovagal BRS were documented in older patients with NMS. Age related autonomic compensatory mechanisms during OS may trigger different vasovagal responses.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".