Ozawa Y, Nagasawa M, Tanigawa N, Tokutake E, Yumikura H, Tsuzi M, Watanabe I, Saito T, Saito S, Hatano M
J Cardiogr. 1983 Mar;13(1):137-47.
We studied eight mongrel dogs, weighing 15 to 35 kg, in which an initial low-frequency vibration of the first heart sound (M-sound) was recognized on the chest wall. A miniature accelerometer weighing 0.5 gm was used to record surface velocity signals and surface acceleration signals as well as phonocardiograms over the cardiac apex of the closed chest wall and over the pericardium or epicardium. The frequency response of accelerometer was essentially flat (+/- 1.5 dB) from 1 to 200 Hz. The accelerometer mounted was such that its sensitive axis was perpendicular to the recording surface. Equisensitive phonocardiograms were obtained to compare the signal size of M-sound on the epicardium at several positions including the cardiac apex, the left ventricular anterior wall near the interventricular septum, the left ventricular antero-lateral wall and the right ventricular anterior wall. Intraventricular phonocardiograms and pressure curves were obtained by a Millar catheter directly inserted through the left ventricular wall near the apex to keep the tip near the apex. Furthermore, the relationship between M-sound and the shortening of the myocardium at the apex was investigated by means of ultrasonic dimension system and phonocardiography. Studies of M-sound were performed not only in sinus rhythm, but also in atrio-ventricular dissociation and ventricular pacing after crushing sinus node or electrical vagus stimulation. The results were as follows: The M-sounds over the chest wall, pericardium and epicardium were recorded coincidentally with the onsets of the left ventricular pressure curve, its dP/dt, low-frequency vibration of the first heart sound of intraventricular phonocardiogram, positive velocity, and acceleration of myocardial surface. The M-sound on the epicardium was maximal in intensity at or near the cardiac apex, in comparison with those recorded on the left ventricular anterior wall near the interventricular septum, left ventricular antero-lateral wall, and right ventricular anterior wall. The M-sound was observed between A and C points of the mitral valve echogram. There was no effect of atrial contraction on the M-sound in cases of atrio-ventricular dissociation. The onset of the M-sound on the epicardium at the apex was not always coincident with the onset of shortening of the myocardium at the same position.(ABSTRACT TRUNCATED AT 400 WORDS)
我们研究了8只体重在15至35千克之间的杂种犬，这些犬在胸壁上可识别出最初的心音低频振动（M音）。使用一个重0.5克的微型加速度计记录封闭胸壁的心尖、心包或心外膜表面的速度信号、表面加速度信号以及心音图。加速度计的频率响应在1至200赫兹范围内基本平坦（±1.5分贝）。安装的加速度计使其敏感轴垂直于记录表面。获取等灵敏度心音图以比较在心尖、室间隔附近的左心室前壁、左心室前外侧壁和右心室前壁等几个位置的心外膜上M音的信号大小。通过直接插入心尖附近左心室壁的Millar导管获取心室内心音图和压力曲线，使导管尖端靠近心尖。此外，借助超声尺寸系统和心音图研究了心尖处M音与心肌缩短之间的关系。对M音的研究不仅在窦性心律下进行，还在压迫窦房结或电刺激迷走神经后的房室分离和心室起搏状态下进行。结果如下：胸壁、心包和心外膜上的M音与左心室压力曲线的起始、其dP/dt、心室内心音图第一心音的低频振动、心肌表面的正向速度和加速度同时记录。与在室间隔附近的左心室前壁、左心室前外侧壁和右心室前壁记录的M音相比，心外膜上的心尖处或其附近的M音强度最大。在二尖瓣超声心动图的A点和C点之间观察到M音。在房室分离的情况下，心房收缩对M音没有影响。心尖处心外膜上M音的起始并不总是与同一位置心肌缩短的起始一致。（摘要截短至400字）
