正常台灣族群心率變異性之性別與姿勢差異

Abstract

心率變異性(heart rate variability, HRV)分析是一種測量連續心跳中，心搏與心博之間變化程度的方法。事實上，正常的心跳會因為受到自主神經系統的調控，而產生波動，這種波動會因自主神經失調受到影響而消失。因此，當變異消失或明顯降低時，會產生沒有波動而完全規律的心率，這種心率被認為是心臟自主神經調節系統異常的表現。HRV目的在於測量心率快慢差異的規律，且可提供非侵襲性的方式來測量自主神經系統的平衡性。會造成其改變的因素有很多，除了年紀和性別，族群外，還會因為其他病理因素，如心肌梗塞， 糖尿病，心臟衰竭等等而造成HRV的下降。使用HRV來評估心血管或精神病患之自主神經狀況非常符合經濟效應，也比其他侵入性的檢查安全，減少了許多不必要的危險性。為了提供臨床上更確切的數據，判斷該病患的HRV是由於年紀增長或男女差異所造成之自然下降抑或是因為病變的產生，需要建立正常數據的範圍。本研究之目的在於建立屬於台灣人正常族群的資料庫，並以性別分類，研究性別差異是否顯著，同時建立其正常範圍。同時亦增加姿勢差異的比較，研究不同姿勢時，心率變異性的改變以及其趨勢。 由年滿二十歲以上的大學學生志願參加本實驗。參與實驗之總人數包含115名，年紀範圍為20-30歲。男性占57名，平均年齡為24 ± 1歲，女性占58名，平均年齡為23 ± 5歲。本實驗所使用的機器為台灣達楷生醫科技所研發的DailyCare BioMedical’s ReadMyHeartR。實驗過程中，所有受測者需變化三種不同的姿勢測量HRV，分別為仰臥，坐姿，以及站姿，各測量五分鐘，其間並休息五分鐘。 本研究之結果顯示，使用短程HRV測量時，性別與姿勢都對頻域分析有很大的影響。在仰臥時，HF的數值最大，代表著此時副交感神經的高活性。而站立時，LF，與LF/HF的數值最大，代表著此時交感神經有最高活性，且在此時交感神經活性大於副交感神經。由以上結果，本研究可歸納以下幾點結論： 1. 心率變異性之頻域分析中之LF及LF/HF呈現男高女低的顯著差異。男性在不同的姿勢中，都較女性高。這應該是因為男性之交感神經活性優於女性。 2. 心率變異性之頻域分析中之HF呈現男低女高的顯著差異。女性之HF在不同的姿勢中，都比男性高，推論其可能原因為女性受到賀爾蒙的影響使得迷走神經活性較高。 3. 心率總變異性在時域與頻域分析皆以仰臥時最大，站立時最小，且有統計上的顯著差異。 4. HF在躺著的時候最大，而站立時有最大的LF與LF/HF。因為在仰臥時，副交感神經活性最大而站立時交感神經活性增強之故。 5. HF高時心率變異性大；而LF與LF/HF高時，心率變異性則會降低。

Heart rate variability (HRV) analysis has been used for many years to measure ANS activities for its simplicity, accuracy, and noninvasiveness. Recent studies show that HRV may be a powerful technique to measure the modulation and balance between parasympathetic nervous system (PNS) and sympathetic nervous system (SNS) by time and frequency domain analysis. It’s believed that decreased HRV is a sign of autonomic nerve system(ANS) imbalance, which may be caused by diseases, and with aging, the HRV decreases. Gender specific normal limits of HRV should be established to distinguish the normal decrease of HRV from pathological decreases in diseased conditions. The aim of the present study is to establish the gender dependent HRV normal limits in a healthy Taiwanese student population. Otherwise, posture differences of short term (5 minutes) time domain and frequency domain HRV parameters were analyzed to distinguish the different postures effect the ANS. This study was performed at College of Biological Science and Technology, National Chao Tung University. A total of 115 healthy students from the university (57 males, aged 24 ± 1 years, and 58 females, aged 23 ± 5 years) without evidence of any heart disease by history and routine medical checkup were recruited for this study. The short term HRV recording was derived from the Modified Lead II-ECG, by a locally developed and manufactured device, DailyCare BioMedical’s ReadMyHeartR. All subjects were asked for lying, sitting, and standing each for 5-minute recording, and all of them must rest for at least 5 minutes before the measurement. The statistically significant results differences from lying to sitting, lying to standing, and sitting to standing and the difference between genders on different postures were demonstrated. SDNN and RMSSD also decreased from lying to standing(P≦0.01, table 1), except lying to sitting of SDNN(P＞0.05). Total power, representing the autonomic tone, also declined from lying to standing (P ≦0.01, table 2 and 3), except lying to sitting. Both the HF and HF norm decreased from lying to standing (P ≦ 0.05). The LF norm and LF/HF ratio increased from lying to standing (P≦ 0.01). From the results, we concluded that: 1. There was a statistically significant sex difference in frequency domain HRV parameters in all postures. The LF and LF/HF of male is greater than female in all postures. This might imply that sympathetic tone of male is higher than that of female. 2. The high HF of female is greater than male in all postures. This might imply that parasympathetic tone of female is higher than that of male. 3. There was a statistically significant posture difference in both time and frequency domain HRV parameters. The HRV of lying is greatest, and the HRV of standing is smallest. 4. HF component is the largest while lying, and LF and LF/HF are the largest while standing. This means that highest activity of parasympathetic tone while lying, and highest activity of sympathetic tone while standing. 5. While HF component is larger, HRV become larger. And while LF component and LF/HF are larger, HRV become smaller.