I sometimes experience that Troponin T levels remarkably elevate although there is no evidence of ischemic heart disease; ECG is normal and USG shows no abnormal cardiac motion. Recently, I have read the article written by Dr. Andrew Turner; Myocardial cell injury in septic shock. Turner A, Tsamitros M, Bellomo R.. Crit Care Med. 1999 Sep;27(9):1775-80. I understand that, under septic condition, cardiac cells may be damaged by supposedly compensated cardiac function, leading to elevated serum Troponin T levels. However, in this case, I suppose that subtle changes in ECG or USG may be detected. I also think that high Troponin T levels may be caused by potential catecholamine-induced cardiomyopathy or Takotsubo cardiomyopathy. Could give me some opinions about this condition?
Mechanism is largely unknown. Please have a look at an interesting experimental paper in this month's issue of JAHA (Makara et al).
I don´t know the mechanism but in up to 50% of patients myocardial dysfunction can be seen on echo. One theory is that myocardial microvasculature is the problem.
Troponin is a marker of myocardial cell injury. When raised in myocardial infarction it is secondary to myocardial necrosis. ECG changes are also secondary to myocardial damage affecting the electrical activity of the heart. But in some cases - even in MI - there is a discrepancy between the two - and hence ECG changes were classified into STEMI and Non-STEMI. In unstable angina for example, there may be ECG changes without significant Troponin rise. With time, more and more highly sensitive Troponin tests are available (High sensitivity Troponin I) which may result in more false positive results. Moreover, cardiac affection can occur in many ICU conditions other than sepsis (e.g. Subarachnoid hemorrhage, stroke, post-arrest).
Stress cardiomyopathy (Takutsubo) is a specific type with published diagnostic criteria and suggestive echo findings (Komamura K etal. Takotsubo cardiomyopathy: World Journal of Cardiology. 2014;6(7):602-609). It is not surprising that Troponin - as a marker of myocardial damage - is elevated in those conditions.
It is important to note that not just the Troponin is elevated in sepsis, but other markers like BNP (Rivers EP et al. J Intensive Care Med. 2007;22(6):363-73). Echocardiography shows a wide range of abnormalities in 40-50% of cases. Recently, more sensitive Echocardiographic techniques resulted in even higher detection of cardiac dysfunction (e.g. Strain imaging by speckle tracking echocardiography).
Septic cardiomyopathy is well described common phenomenon. It consists the cardiac part of multiple organ dysfunction associated with sepsis. In 1951, Waisbren was the first to describe a subtype of septic patients with hypodynamic circulation (Waisbren BA. AMA Arch Intern Med. 1951;88: 467– 88). This had been confirmed by a pioneer work by Parker et al in 1984 (Parker MM et al. Ann Intern Med. 1984; 100:483– 90). Septic cardiomyopathy can occur in 40-50% of septic shock patients, involving the left as well as the right heart, diastolic and systolic function.
Many mechanisms had been implicated to explain septic cardiomyopathy. Overt coronary artery disease had been largely excluded by pioneer work since 1980s. In fact, coronary blood flow is increased in sepsis while oxygen extraction is diminished (Cunnion RE el al. Circulation 1986; 73: 637–44). Animal model suggested a circulating myocardial depressant substance (Parrillo JE et al. J Clin Invest. 1985;76:1539-53). Many molecules had been accused (e.g. Endotoxin, IL1, TNF, NO). Other possible mechanisms include myocardial dysfunction, apoptosis, microcirculatory failure.
In general, septic cardiomyopathy remains an interesting area of research and current and future works should increase our understanding of the condition.
Best regards.
A good review article on that issue by Hussain N.
http://dx.doi.org/10.1155/2013/723435
Thanks everyone for helping me with some articles and valuable opinions! I think that bacteremia and septicemia affect not only liver and kidney but also some other organs. I understand that changes in US and ECG may be resulted from cardiac damage or ventricular overload. I am looking forward to your good luck and working with you in the future! ：）
When sepsis involves myocardium and causing myocarditis , it will cause elevation in the cardiac bio markers.
Thanks for many comments for my question! I stay focused on this interesting phenomenon.
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