[Studies of heart rhythm variability in migraine. Preliminary communication]. / Badanie zmiennosci rytmu serca w migrenie. Doniesienie wstepne.

Spectral analysis of hart rhythm variability makes possible assessment of the state (power) of autonomic innervation of the heart. The reported study was carried out in 40 patients (22 women) with migraine. The studies were done in times between migraine attacks. The control group comprised 62 clinically healthy subjects. In most patients (over 61%) the sympathetic and parasympathetic innervation of the heart was weaker than in healthy subjects and the index of automatic equilibrium in the sinus node was lower than in controls.

[The effect of orthostatic provocation on the spectral pattern of heart rate variability in healthy subjects]. / Wplyw prowokacji ortostatycznej na widmo zmiennosci rytmu serca u zdrowych.

Investigations were carried out in 74 persons (32 female and 42 male, mean age: 39.7 +/- 10.0 years, range: 16 to 68 years) free of diseases known to affect autonomic function. After a quarter of rest in quite, air conditioned room, while on voluntary breathing in supine, and later on in vertical position, time-series of a few minutes of successive R-R intervals were collected in each person and than stored for further off line analysis. Multivariate autoregressive modeling approach with parametric decomposition of peaks has given a basis for computation of spectral power of heart rate variability. In each body position 150 seconds long, stationary epoch of R-R intervals free of ectopy and artifacts were selected, and spectral power were calculated in three frequency bands: very low frequency (VLF): below 0.03 Hz (rejected from further analysis), low frequency (LF): from 0.03 to 0.15 Hz, and high frequency (HF): 0.15 to 0.35 Hz. Than, computed powers were expressed in either absolute units, or as normalized values, that is as percentages of total power less VLF. Breathing was also monitored in each case and spectral characteristics of its frequency also given in ranges defined for heart rate variability. In vertical, as compared to supine position, mean R-R interval decreased: 856 +/- 119 ms vs. 695 +/- 111 ms (p < 0.0005). The power of LF increased: 8.1 +/- 7.3 BPM2 vs. 19.2 +/- 14.6 BPM2, (p < 0,005), and simultaneously the power of HF dropped: 4.7 +/- 3.6 BPM2 vs. 2.7 +/- 2.5 BPM2, (p < 0.0005). In normalized units LF power enhanced: 63 +/- 385 vs. 87 +/- 42%, (p < 0.0005), and HF dropped: 36.7 +/- 32% vs. 12.3 +/- 12%, (p < 0.0005). Autonomic balance expressed as LF/HF ratio was higher in vertical position: 2.0 +/- 1.6 vs. 11.0 +/- 8.7, (p < 0.0005). In 73 out of 74 subjects (98.6%) the power of LF increased, and in 71 (95.9%)-decreased. In one person who had lower power of LF in vertical than supine position, the increase of HF power was noticed. Mean percentage increase of LF in the whole group was 209.4 +/- 243%, but after rejection of the result mention above the mean value increased to 218 +/- 22.1%. Mean percentage decrease of HF power in the whole group was 34.7 +/- 37.7%, and increased to 39.5 +/- 26.9% after rejection of three results with changes in opposite direction. Mean values of respiratory power did not change with switching of posture neither in LF:14.4 +/- 6.6% vs. 17.8 +/- 7.1%, (NS), nor in HF: 77.7 +/- 9.2% vs. 73.6 +/- 12.1%, (NS).

Efficacy and safety of dofetilide in the prevention of symptomatic episodes of paroxysmal supraventricular tachycardia: a 6-month double-blind comparison with propafenone and placebo.

BACKGROUND: Existing drug therapies for paroxysmal supraventricular tachycardia (PSVT) have potentially serious adverse effects. Dofetilide, a pure class III antiarrhythmic agent, may offer an effective and safe alternative for treating PSVT. This study compared the efficacy and safety of dofetilide with that of propafenone and placebo in the prevention of PSVT. METHODS: This multicenter, randomized, placebo-controlled, parallel-group study compared the effectiveness of oral dofetilide 500 microg given twice daily with that of propafenone 150 mg given 3 times a day and placebo in preventing the recurrence of PSVT in 122 symptomatic patients. Episodes of PSVT were documented by symptom diaries and Hertcard (Hertford Medical, Hertfordshire, UK) event recorders. RESULTS: After 6 months of treatment, patients taking dofetilide, propafenone, and placebo had a 50%, 54%, and 6% probability, respectively, of remaining free of episodes of PSVT (P <.001 for both dofetilide and propafenone vs placebo). Both dofetilide and propafenone also decreased the frequency of episodes of PSVT; the median numbers of episodes in the dofetilide- and propafenone-treated groups were 1 and 0.5, respectively, compared with 5 in the placebo-treated group. Dofetilide was well tolerated; no proarrhythmia occurred. Three patients taking propafenone had serious treatment-related adverse effects that required drug discontinuation. CONCLUSIONS: Dofetilide and propafenone were equally effective in preventing the recurrence of or decreasing the frequency of PSVT.