Mortara A, Sleight P, Pinna G D, Maestri R, Prpa A, La Rovere M T, Cobelli F, Tavazzi L
Division of Cardiology, Centro Medico di Montescano, S. Maugeri Foundation, IRCCS, Pavia, Italy.
Circulation. 1997 Jul 1;96(1):246-52. doi: 10.1161/01.cir.96.1.246.
Reduced heart rate variability, particularly in the Very-low-frequency (VLF) spectral band, has been found to be a marker for poor prognosis in patients after myocardial infarction, but the origin of the VLF oscillations is unclear. In this study, we demonstrate that the power of cardiovascular oscillations in the VLF band in awake patients with mild to severe chronic heart failure is greatly increased by the common occurrence of unrecognized irregularity of breathing, which may confound the use of heart rate variability measures as indexes of autonomic tone or prognosis.
Among 110 consecutive patients referred for consideration of transplantation, 90 were in sinus rhythm, of whom 10 were excluded as unstable. The remaining 80 patients underwent recordings of ECG, beat-to-beat arterial oxygen saturation (SaO2), and respiration during both spontaneous and controlled breathing. During spontaneous awake breathing, 64% showed periodic breathing or Cheyne-Stokes respiration (CSR), which was associated with dominant power in the VLF band of all signals. This VLF power accounted for 55%, 77%, and 87% of heart rate variability, respectively, in patients with normal breathing, periodic breathing, and CSR. It was reduced by 48% and 62%, respectively, during controlled breathing in patients with periodic breathing or CSR. Controlled ventilation also improved oxygen saturation and markedly reduced its variability.
Breathing disorders are surprisingly common in awake patients with poor left ventricular function and produce large VLF oscillations in heart rate variability. If measures of heart rate variability are used for prognostic purposes during both short-term and long-term recordings, the confounding effects of variable respiratory patterns should be excluded. Respiratory rehabilitation might help control potentially hazardous surges in sympathetic tone.
心率变异性降低，尤其是在极低频（VLF）频段，已被发现是心肌梗死后患者预后不良的一个标志，但VLF振荡的起源尚不清楚。在本研究中，我们证明，在轻度至重度慢性心力衰竭的清醒患者中，未被识别的不规则呼吸的普遍存在会大大增加VLF频段心血管振荡的功率，这可能会混淆将心率变异性测量用作自主神经张力或预后指标的用途。
在110例连续被转诊考虑进行移植的患者中，90例为窦性心律，其中10例因病情不稳定被排除。其余80例患者在自主呼吸和控制呼吸期间进行了心电图、逐搏动脉血氧饱和度（SaO2）和呼吸记录。在自主清醒呼吸期间，64%的患者表现出周期性呼吸或潮式呼吸（CSR），这与所有信号的VLF频段的主导功率相关。在呼吸正常、周期性呼吸和CSR的患者中，这种VLF功率分别占心率变异性的55%、77%和87%。在周期性呼吸或CSR的患者中，控制呼吸期间VLF功率分别降低了48%和62%。控制通气还改善了血氧饱和度并显著降低了其变异性。
呼吸障碍在左心室功能不良的清醒患者中出人意料地常见，并在心率变异性中产生较大的VLF振荡。如果在短期和长期记录期间将心率变异性测量用于预后目的，则应排除可变呼吸模式的混杂效应。呼吸康复可能有助于控制交感神经张力的潜在危险波动。
