Hyperacute T-wave

今天evening nephro round Dr.楊請大家上台畫出MI和hyperkalemia其個別hyperacute T-wave。你能描述差異在哪並畫出來嗎?

Wikipedia:

The earliest electrocardiographic finding of acute myocardial infarction is sometimes the hyperacute T wave, which can be distinguished from hyperkalemia by the broad base and slight asymmetry.

http://en.wikipedia.org/wiki/Electrocardiogram#T_wave

→高血鉀的hyperacute T wave是寬底而有微小的不對稱。

UpToDate:

Peaked T waves —
Hyperacute or peaked T waves are usually the result of hyperkalemia. They are generally >10 mm in height as measured in the precordial leads, and >5 mm in height in the limb leads. The T wave is not only tall, but it is peaked and symmetric. This appearance is in contrast to the normal T wave which is asymmetric (the initial upstroke is slow while the end or downstroke is rapid).

In addition to hyperkalemia, hyperacute T waves may be seen in the early phases of an acute myocardial infarction or with myocardial ischemia, conditions which are associated with localized extracellular hyperkalemia. Tall T waves may also be seen in the presence of left ventricular hypertrophy, in which the amplitude of the QRS complex is increased, or may even be a normal variant; in these cases, the T waves are not peaked and still have an asymmetric morphology.

Hyperacute (peaked) T waves

Hyperacute T waves are >5 mm in the limb leads, and usually >10 mm in the precordial leads. They have a peaked, symmetric morphology.

http://www.uptodate.com/online/content/topic.do?topicKey=electuto/6828&selectedTitle=7~150&source=search_result#14

→高血鉀的T wave又高又尖又對稱。
有多高呢?在前胸導，常高於2大格；在肢導，長高於一大格。

→AMI早期可能看到hyperactue T wave
(基本理論是 localized "extra"cellular hyperkalemia，
我是第一次看到說明AMI有hyperactive T wave的原因，似乎蠻合理的)
這時後的T waves的確是有高起來，但是並沒有到 peaked的程度，
而且T wave的形狀是不對稱的。

ABC of clinical electrocardiography

The earliest signs of acute myocardial infarction are subtle and include increased T wave amplitude over the affected area. T waves become more prominent, symmetrical, and pointed ("hyperacute"). Hyperacute T waves are most evident in the anterior chest leads and are more readily visible when an old electrocardiogram is available for comparison. These changes in T waves are usually present for only five to 30 minutes after the onset of the infarction and are followed by ST segment changes.


















http://www.bmj.com/cgi/content/full/324/7341/831

→AMI的hyperacute T wave經常是MI剛開始5到30分鐘的心電圖表現，
過了半小時後就會開始ST chamge。

阿倫小筆記：

Tall, peaked, symmetrical, broad base T waves
= Hyperkalemia T wave !!

peaked,ㄚ是有多尖呢？應該是可以刺傷手指頭吧 :)




Tall, asymmetrical, very broad baseT waves

= AMI hyperacuteT wave !!

不對稱的T波是緩升陡降，為什麼會緩升是因為常伴隨ST segment change，如果詢問有胸痛情形，接下來應該是馬上進行近乎反射的動作：MONA+call CV man+評估thrombolytic agent使用。