心电监护基础知识（四）心电图组成与测量

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                    <p><span>心电监护基础知识（四）心电图组成与测量</span></p><p><span><br  /></span></p><p><span> </span></p><p><span>4.9、心电图的组成与测量</span></p><p><span> <p><img src="image/20201019/18c7145a7effe9030934428ec7d78274_1.png" /></p><br  /></span></p><p><span>4.9.1<span>、正常的心电图各波段的命名及意义</span> </span></p><p><span><span>每个正常心动周期的心电图曲线由以下各波组成：第一个波为</span>P<span>波，是心房电活动波，第二个波为</span>QRS<span>波群，第三个波为</span>T<span>波，</span>QRS<span>－</span>T<span>波群为心室的电活动波。</span> </span></p><p><span> </span></p><p><span>P<span>波：波组中第一个出现的小波，代表左、右心房除极过程。</span>I<span>、</span>II<span>、</span>avR<span>，</span>V3<span>～</span>V6<span>正向，波顶园钝，光滑，可有轻微切迹，切迹间距</span>&lt;0.04<span>，</span>avR<span>倒臵，</span>III<span>、</span>avL<span>、</span>V1<span>、</span>V2<span>可正、负双向，</span>P<span>波宽</span>&lt;0.115s<span>（秒），</span>P<span>波电压肢导联</span>&lt;0.25mV<span>，胸导联正向</span>&lt;0.15mV<span>，双向</span>&lt;0.2mV<span>。</span> </span></p><p><span> </span></p><p><span>P<span>－</span>R<span>间期（</span>P<span>－</span>Q<span>间期）；自</span>P<span>波起点至</span>QRS<span>波群起点之间的时限，代表激动自窦房结经心房、房室交界区、房室束、左右束支、浦氏纤维到达心室，并引起心室兴奋所需的时间，正常成人</span>0.12~0.20S<span>，儿童</span>0.12~0.18S<span>、心率不同、</span>P<span>－</span>R<span>最高值也不同。</span> </span></p><p><span> </span></p><p><span>QRS<span>波群：心室除极波的总称。第一个向下的波为</span>Q<span>波，第一个向上波为</span>R<span>波，</span>QS<span>波：全部向下的波。</span>QRS<span>波群各波的振幅高低深浅不同，分别以大小写的字母表示，如</span>R<span>、</span>RS<span>、</span>qR<span>、</span>Rs<span>、</span>Rs<span>、</span>qRs<span>、</span>rSr<span>等。正常</span>Q<span>波振幅</span>&lt;1/4R<span>，不超过</span>0.3mV<span>，波宽</span>&lt;0.04s<span>，不应有切迹，</span>V1<span>、</span>V2<span>导联正常时不应有</span>Q<span>或</span>q<span>波，但可呈</span>QS<span>型。一般</span>R1&lt;1.5mV <span>，</span>avR&lt;0.5mV<span>，</span>RavL&lt;1.2mV<span>，</span>RV1&lt;1.0mv<span>，</span>RVS&lt;2.5mv<span>。</span>QRS<span>时限代表心室肌动过程所需时间，成人为</span>0.06~0.10s<span>。</span> </span></p><p><span> </span></p><p><span>ST<span>段：由</span>QRS<span>波群终点至</span>T<span>波开始的一段，反映心室肌早期复极过程的电位变化，正常应基本在等电位线。</span>      </span></p><p><span><br  /></span></p><p><span>ST</span><span>段偏移的正常范围：</span><span> </span></p><p><span>      <span>抬高：肢导联抬高</span>&lt;0.1mv<span>，胸导联抬高</span>V1<span>～</span>V3&lt;0.3mv  V5~V                          6&lt;0.1mv<span>。</span>        </span></p><p><span><span>压低：</span>ST<span>段压低除</span>III<span>导可达</span>0.1mv<span>外，余导联均</span>&lt;0.05mv<span>。</span> ?</span></p><p><span> </span></p><p><span>T<span>波：心室复极波，是紧接</span>ST<span>段后的一个较低而占时较长的波。一般呈园钝状，平滑而宽大，一般无切迹，上升支缓慢，下降支较陡。</span> <span>在</span>I<span>、</span>II<span>、</span>V4<span>～</span>V6<span>正向，</span>AaR<span>倒臵，</span>TV3<span>多正向。</span>T<span>波正向导联不应低于同导</span>R<span>波的</span>1/10<span>。</span> </span></p><p><br  /></p><p><span>Q<span>－</span>T<span>间期：从</span>QRS<span>波群起始至</span>T<span>波终未间的时间间隔，代表心室除极复极过程所需的全部时间，正常范围应为</span>0.36~0.44s<span>。</span> </span></p><p><br  /></p><p><span>T<span>－</span>P<span>段：自</span>TCU<span>波结束到下一个心动周期</span>P<span>波开始的一段（实为</span>U<span>－</span>P<span>段）。代表心室完全复极完毕。此段又称为基线或电平线。</span> </span></p><p><span><br  /></span></p><p><span><p><img src="image/20201019/df1c2eb09b3189e573942cb954365e1d_2.png" /></p><br  /></span></p><p><br  /></p>