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Troponin I, Troponin T, or Creatine Kinase-MB to Detect Perioperative Myocardial Damage After Coronary Artery Bypass Surgery: Discussion

The main findings of our study were that (1) in noncomplicated postoperative CABG, cTnl values remained constantly low, contrasting with very high values when perioperative myocardial infarction occurred, and (2) there was little difference between cTnl, cTnT, and CKMB to diagnose myocardial damage after CABG as assessed by the appearance of new Q wave on the ECG.
Troponins and CABG
Troponins are regulatory proteins (I, C, T) located in the striated muscle. They regulate actinomyosine interactions. These proteins have a small cytosol distribution with the majority being tightly com-plexed to the contractile apparatus. Plasma levels are low in healthy patients. With acute myocardial lesion, plasma cTnl or cTnT concentration increases rapidly due to the release of the cytosolic fraction. Cell death and destruction of its contractile apparatus induce continued release of troponins for 1 week. cTnl is highly specific for myocardial injury, it is expressed only in the myocardium in adults, whereas CKMB and cTnT are expressed in the regenerating skeletal muscles as well. In patients with severe skeletal muscle damages, cTnT increases in 95% and correlated strongly with the peak activity of serum creatine kinase.
After CABG, there is a small increase in cTnl. Dissection of the myocardium for exposure of the intramyocardial arteries, manipulation of the myocardium, and placement of the purse string sutures for cannulation cause myocardial lesions. These injuries may explain why cTnl was detectable just before aortic declamping and increased early. Antibiotics online read more However cTnl concentrations remained low in the noncomplicated group (group 1), suggesting that lesions were minimal. This slight increase is also observed with cTnT and CKMB mass. The median values observed for peak cTnl (2.1 μg/L) and cTnT (0.17 μg/L) in patients without new Q wave were consistent with previously published data.
cTnl, cTnT, CKMB Mass, and Perioperative Myocardial Infarction
Perioperative myocardial infarction is one of the major problems during CABG. Its incidence was estimated at 6.4% in the Coronary Artery Surgery Study trial. However, its prevalence depends on the tests and diagnostic criteria used. No standards are widely accepted. Postoperative sedation and sternotomy make clinical symptoms unreliable.

Category: Myocardial Damage

Tags: coronary artery bypass surgery, creatine kinase, myocardial infarction, troponin I, troponin T