What can be seen on the screen when stress echocardiography (a pair of heart ultrasounds before and after exercise) suggests ischaemia? Can this happen without chest pain?
Illustration from Wikipedia:
$\begingroup$
$\endgroup$
Add a comment
|
1 Answer
$\begingroup$
$\endgroup$
5
A number of things can be seen. Ischaemia is typically caused by the narrowing of blood vessels that prevents perfusion (blood flow) to the heart or other organs. When the heart muscle doesn't get enough oxygen, the walls of the heart might not "beat" (i.e. contract) properly. We observe this and thus can tell if a coronary artery is reduced or blocked or fine. It doesn't give absolute numbers of how blocked it is, although observation of the way the muscle moves can give some indication. Contrast can further allow us to visualise the wall with more detail, giving a clearer indication of coronary artery disease in the vessels that supply this part of the heart.
Pain is caused when the heart muscle is really suffering, which doesn't occur unless the vessels are seriously blocked. They're so great that even if about 70% of the artery is blocked there is almost no effect including chest pain. In fact it is silent, which is quite worrying also. However, when the heart is most stressed, we can potentially detect decrease in perfusion from small changes in the contraction of the heart.
answered May 20, 2013 at 20:31
-
$\begingroup$ Many thanks for the answer. Is injecting a dye a usual part of standard stress echocardiography? Or is a dye injected during stress echocardiography under some special conditions? $\endgroup$– winerdCommented May 21, 2013 at 15:06
-
$\begingroup$ Your answer makes me think me that ischaemia should be visible with plain echocardiography. Is the second echocardiography after exercise important? $\endgroup$– winerdCommented May 21, 2013 at 15:19
-
$\begingroup$ You answered that in stress echocardiography we "see how it responds to increased exercise (does the blood flow increase by the same amount everywhere?)". 10 days ago Xaqron answered "echocardiography [was] not sensitive enough to do so". Was Xaqron wrong? $\endgroup$– winerdCommented May 21, 2013 at 15:26
-
1$\begingroup$ You can't visualise it directly. Basically you compare the baseline (at rest) to the stressed heart. What you specifically compare is the motion of the walls. The important word here is "compare". Without a baseline you can't see as much. Contrast (i.e. the dye) enhances visualisation where it is difficult to see wall thickening. $\endgroup$ Commented May 21, 2013 at 17:28
-
$\begingroup$ I've updated the answer to make it more clearer. You can't tell the flow difference directly, but you can indirectly by measuring the differences in the way the heart contracts. As there's a lot of other factors at play (oxygen concentration of the blood, anaemia etc.) you can't simply equate flow and the observations on an echo. As you are keeping most of these variables constant by doing a before and after, the only thing really affected is flow which is decreased dramatically by thickening of the blood vessels, which you can thus measure. $\endgroup$ Commented May 21, 2013 at 17:41