Higher heart rate increments on head-up tilt in control subjects are not associated with autonomic dysfunction

A prospective 1-year study of postural tachycardia and the relationship to non-postural versus orthostatic symptoms

PURPOSE

Healthy subjects with asymptomatic postural tachycardia at baseline were evaluated over a one year period to determine whether they developed non-postural versus orthostatic symptoms that could predispose them to develop Postural Tachycardia Syndrome (POTS).

METHODS

Participants (n=30) were recruited for a 1-year follow-up (FUP) study if at baseline they demonstrated a heart rate increment of ≥30bpm on head-up tilt (HUT). At FUP, HUT was repeated and four self-report questionnaires were used to assess symptoms.

RESULTS

Heart rate (HR) increment was reduced in 19 subjects (-11.8±7.4bpm) and increased in 11 subjects (8.3±6.1bpm) at FUP versus baseline. Heart rate increment at FUP demonstrated no correlation to general fatigue (r=0.006), body vigilance (r=0.195), or the component scores for physical (r=-0.087) and mental (r=-0.137) health of the SF-36. Similarly, there was no correlation between HR increment at FUP and orthostatic scores (r=0.04). However, orthostatic scores did show a significant positive correlation with general fatigue and body vigilance scores (r=0.374, r=0.392, respectively; p<0.05).

CONCLUSIONS

Despite meeting the heart rate criteria for POTS, these findings further support that the majority of young individuals express benign orthostatic tachycardia. In addition, after one year this patient population showed no predisposition to develop non-postural or postural symptoms that could lead to the full syndrome of POTS. These data further argue for the re-evaluation of the heart rate criteria for diagnosing POTS in young populations.

Non-invasive measurement of adrenergic baroreflex during Valsalva maneuver reveals three distinct patterns in healthy subjects

OBJECTIVE

To investigate hemodynamic trans-phasic fluctuations in Valsalva maneuver (VM) and relate them to adrenergic baroreflex sensitivity (BRSa) indices.

METHODS

In a healthy population (n=107) with a young age predominance (32 ± 15 years) systolic blood pressure (SBP) and BRSa indices in VM were studied.

RESULTS

Augmented and Suppressed Autonomic Responses (AAR, 28%; SAR, 15%, respectively), in addition to Balanced Autonomic Response (BAR, 40%), were found. There was a predominance for an unbalanced SBP response (67% in AAR, 69% in SAR, vs. 53% in BAR) in subjects ages 20-29. Compared to BAR and AAR, SAR had insignificant female predominance (51% and 47% vs. 75% respectively, p>0.05). AAR had the highest alternative BRSa (BRSa1) compared to SAR and BAR (26.73 ± 17.97 mmHg/s vs. 8.64 ± 5.33 mmHg/s and 15.68 ± 10.40 mmHg/s respectively, p<0.01).

CONCLUSIONS

Qualitative evaluation revealed three distinct patterns in response to VM. Late phase II was found to be a key factor in VM patterns and as such, argues to include late phase II parameters such as hemodynamic and time indices in BRSa evaluation.

SIGNIFICANCE

These findings may be of use in future evaluations when identifying mild autonomic dysfunction and/or distinguishing typical and atypical SBP patterns in a healthy population.