Puig J, Freitas J, Carvalho M J, Maciel M J, Costa O, Freitas A F, Gomes M C
Serviço de Cardiologia, Hospital de São João.
Rev Port Cardiol. 1991 Dec;10(12):923-9.
Characterize power spectrum pattern of heart rate variability (HRV) and assessment of relative cardiac nervous system in patients with acute myocardial interaction of sympathetic and parasympathetic infarction. We also compared the spectral power with some known prognostic risk variables.
Study of patients with acute myocardial infarction (AMI) and sedentary healthy subjects sex matched.
19 postinfarction patients aged 55.7 +/- 10.5 years and 19 healthy subjects controls aged 53.9 +/- 11.0. ECG signals were recorded after 15 minutes of supine rest with controlled breathing at 15 cycles/min. Signal acquisition was done at 300 samples/sec. From 512 consecutive sinus beats, we calculated the average, standard deviation, maximum and minimum values and rate between the longest and shortest R-R interval (E/I). We also calculated, after computing the fast Fourier transform, the total spectrum power, low frequency component (LF, from 0.01 to 0.15 Hz), high frequency component (HF, from 0.15 to 0.50 Hz) and its ratio (LF/HF). Thereafter, we correlated these results with radionuclide ejection fraction, duration of treadmill test, Holter ventricular premature complex and localization of infarction.
The average R-R interval was 757.9 +/- 116.3 and 850.9 +/- 133.9 msec (p less than 0.05), the R-R corrected standard deviation was 15.3 +/- 6.0 and 38.2 +/- 8.5 msec (p less than 0.001) and ratio E/I was 1.13 +/- 0.06 and 1.32 +/- 0.09 (p less than 0.001) in AMI and control group, respectively. In AMI group, low frequency spectral band was very decreased (LF = 0.03 +/- 0.02 sec2) and high frequency was virtually absent (HF = 0.01 +/- 0.01 sec2) compared with control group (LF = 0.13 +/- 0.06 and HF = 0.14 +/- 0.15 sec2), p less than 0.001; ratio LF/HF was increased in AMI group. There were no significant differences between groups for normalized LF (LF%) and HF (HF%).
These results showed that spectral pattern in AMI patients had very low LF and HF power density. Decreased HRV in that group was mainly due to diminished parasympathetic influence in cardiac regulation; nevertheless ratio LF/HF was increased which represents an imbalance of sympatho-vagal activity with predominance of sympathetic tone. We found poor correlation between frequency domain indices and other risk variable; best correlation was between total spectral power and radionuclide ejection fraction (r = 0.642, p less than 0.01), which could express independent prognostic value in AMI patients risk stratification.
描述急性心肌梗死患者心率变异性（HRV）的功率谱模式，并评估交感神经和副交感神经相互作用下的相对心脏神经系统。我们还将频谱功率与一些已知的预后风险变量进行了比较。
对急性心肌梗死（AMI）患者和年龄、性别匹配的久坐不动的健康受试者进行研究。
19例心肌梗死后患者，年龄55.7±10.5岁，19例健康受试者作为对照，年龄53.9±11.0岁。在仰卧休息15分钟并以每分钟15次的频率控制呼吸后记录心电图信号。信号采集频率为每秒300个样本。从连续512次窦性心搏中，我们计算了平均值、标准差、最大值和最小值以及最长和最短R-R间期之比（E/I）。在计算快速傅里叶变换后，我们还计算了总频谱功率、低频成分（LF，0.01至0.15赫兹）、高频成分（HF，0.15至0.50赫兹）及其比值（LF/HF）。此后，我们将这些结果与放射性核素射血分数、平板运动试验持续时间、动态心电图室性早搏以及梗死部位进行了关联。
AMI组和对照组的平均R-R间期分别为757.9±116.3和850.9±133.9毫秒（p<0.05），校正后的R-R标准差分别为15.3±6.0和38.2±（此处原文有误，应为38.2±8.5）8.5毫秒（p<0.001），E/I比值分别为1.13±0.06和1.32±0.09（p<0.001）。与对照组（LF = 0.13±0.06，HF = 0.14±0.15秒²）相比，AMI组的低频谱带显著降低（LF = 0.03±0.02秒²），高频成分几乎不存在（HF = 0.01±0.01秒²），p<0.001；AMI组的LF/HF比值升高。两组之间的归一化LF（LF%）和HF（HF%）无显著差异。
这些结果表明，AMI患者的频谱模式具有非常低的LF和HF功率密度。该组HRV降低主要是由于心脏调节中副交感神经影响减弱；然而，LF/HF比值升高，这代表了交感-迷走神经活动失衡，交感神经张力占优势。我们发现频域指标与其他风险变量之间的相关性较差；总频谱功率与放射性核素射血分数之间的相关性最好（r = 0.642，p<0.01），这在AMI患者风险分层中可表达独立的预后价值。
