BACKGROUND

A reduction of heart rate variability (HRV) is currently considered an independent risk factor for morbidity, mortality and severity of severalcardiac disease, however, the dynamic sympathovagal modulation on HRV during 24 hr in primary pulmonary hypertension (PPH) had not been described.

METHODS

24 hr Holter monitoring (HA) were recorded in 32 patients (mean age 34, +/-12, 90% female) with severe primary pulmonary hypertension (mean pulmonary pressure, 90:t:12 mm Hg), and in 34 patients (mean age 36 +/-14, 60% female) with Eisenmenger syndrome (ES) secondary to septal ventricular defect or atent ductus arteriosus. A control group (n=44) paired for age, gender and arterial pulmonary pressure was included. HRV time and spectral parameters (mean, SDNN, SDANN, rMSSD, PNN50, LF, HF and LF/HF ratio) were analyzed during three periods: 24 hr; day (8-22:00), night (23-07:00) and also every hour of recording at 5 min-intervals). After detection of sympatho-vagal balance 15 patients were randomized, Treprostinil (prostaglandin) was administered to 6 patients and subcutaneous placebo to 9.

RESULTS

HRV frequency parameters during 24 hr HM were significantly different among groups. LF/HF (day) 5.9:1:12.5:1:1P.001 and LF/HF night) 2.8:tlvs.1.5:l:.8.034. Sympathovagal modulation on 24 hr HRV showed that heart rate circadian rhythm is clearly altered in both PPH and ES, but the sympathetic tone in PPH is higher at l 24 hr. (p < .05), after administering treprostinil a recovery of sympathovagal balance was observed

CONCLUSIONS

Autonomic cardiac disturbance is clearly present in PPH and ES. The circadian rhythm of HRV is first lost due to an increase of sympathetic tone. These changes may be markers of autonomic disbalance that favor the development of arrhythmias and sudden death. The sympathovagal balance in PPH could be considered an important risk marker.