This is called intractable or severe angina , the severity of which is designated by classes .
这被称为难以治愈的或严重的心绞痛，严重性被级别指定。
Researchers believe the loss of these blood vessels contributes to the pain of chronic , severe angina .
研究员认为这些血管的损失是产生慢性疼痛，严重心绞痛的原因。
Other heart conditions such as angina and heart attacks contribute to the disease , according to the u.s. national library of medicine .
根据美国国家医学图书馆记载的资料，它还可能引发其他心脏疾病，如心绞痛或心肌梗塞。
Short sleep duration was associated with angina , while both sleeping too little and sleeping too much were associated with heart attack and stroke , the study says .
研究表明心绞痛与较短的睡眠持续时间有关，心脏病发作和中风则与睡得太少或者睡得太多有关。
It also took twice as long until they experienced angina pain on a treadmill compared to the placebo group , and , when they felt pain , it went away faster with rest .
