National Taiwan University Veterinary Hospital, National Taiwan University, Taipei, Taiwan.
TACS-Alliance Research Center, Taipei, Taiwan.
J Feline Med Surg. 2024 Oct;26(10):1098612X241275296. doi: 10.1177/1098612X241275296.
Stress associated with manipulation during electrocardiography (ECG) recording in cats potentially limits the assessment of autonomic function through heart rate variability (HRV) in the feline population. This study proposed an alternative, cat friendly, stethoscopic approach to evaluate HRV with an easily acquired vasovagal tonus index (VVTI).
The aim of this prospective study was to evaluate whether VVTI derived from heart sound signals could distinguish between relaxed and stimulated states. A total of 29 cats with 56 recordings of heart sound and ECG on 31 occasions were included. In 25 cats in their home environment, a stethoscope connected to a digital recording device was used to record 2 mins of heart sounds twice - with the cats in a relaxed state and immediately after stimulation. The VVTI was calculated from 20, 60 and 120 consecutive beat-to-beat intervals on the heart sound spectrogram (stethoscopic-VVTI 20, 60 and 120), using the natural logarithm of the variance of the intervals based on previous literature. A 2-min ECG recording was obtained at home with the intention of avoiding strict restraint. To demonstrate the feasibility of the stethoscopic approach in a hospital setting, six cats (two of which were also recorded at home) underwent heart sound and ECG recordings during planned veterinary visits.
Stethoscopic-VVTI 20 (5.43 to 4.79, = 0.001), 60 (6.20 to 5.18, <0.001) and 120 (6.24 to 5.60, = 0.02) all significantly decreased after stimulation, indicating a reduced vasovagal tone as expected. Calculations of stethoscopic-VVTI from different sections of the recording yielded statistically similar results. Stethoscopic-VVTI showed a negative correlation with the corresponding heart rate. Bland-Altman analysis revealed a mean bias for the differences between stethoscopic-VVTI and ECG-VVTI of 0.50 and 1.07 at home and in the hospital, respectively.
VVTI can be successfully detected through a stethoscopic approach, serving as a less stressful tool for HRV evaluation in cats during routine auscultation.
在猫的心电图（ECG）记录过程中，与操作相关的压力可能会限制通过心率变异性（HRV）评估猫的自主功能。本研究提出了一种替代的、对猫友好的听诊方法，通过易于获得的血管迷走张力指数（VVTI）来评估 HRV。
本前瞻性研究的目的是评估从心音信号中获得的 VVTI 是否可以区分放松和刺激状态。共纳入 31 次 29 只猫的 56 次心音和 ECG 记录。在 25 只猫的家中环境中，使用连接到数字记录设备的听诊器记录 2 分钟的心音，两次 - 一次在猫放松状态下，一次在刺激后立即。从心音频谱图上的 20、60 和 120 个连续的心跳间隔计算 VVTI（听诊器-VVTI 20、60 和 120），使用基于先前文献的间隔方差的自然对数。在家中进行 2 分钟的 ECG 记录，旨在避免严格的限制。为了证明听诊方法在医院环境中的可行性，六只猫（其中两只也在家中记录）在计划的兽医就诊期间进行了心音和 ECG 记录。
刺激后，听诊器-VVTI 20（5.43 至 4.79，=0.001）、60（6.20 至 5.18，<0.001）和 120（6.24 至 5.60，=0.02）均显著降低，表明预期的血管迷走张力降低。从记录的不同部分计算听诊器-VVTI 得出的结果具有统计学上的相似性。听诊器-VVTI 与相应的心率呈负相关。Bland-Altman 分析显示，在家中和医院，听诊器-VVTI 和 ECG-VVTI 之间差异的平均偏差分别为 0.50 和 1.07。
通过听诊方法可以成功检测到 VVTI，作为在常规听诊时评估猫 HRV 的一种压力较小的工具。
