Jothilingam, N (2013) Post Operative Troponin-T level as a marker of Extent of myocardial ischemic injury in mitral Valve replacement surgeries. Masters thesis, Madras Medical College, Chennai.
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Abstract
INTRODUCTION: Cardiac surgery is often complicated by some degree of myocardial ischemic damage, despite much improvement in myocardial protection strategies and surgical techniques. But, precise markers that can easily and specifically identify and quantify the extent of such damage is lacking. Electrocardiographic changes are of limited value in the perioperative period. Trans-esophageal echocardiography may be helpful in assessing left ventricular function and regional wall motion (which are indirect indicators of adequacy of myocardial protection) but it lacks the sensitivity to detect subtle degrees of myocardial damage. But, it is very essential to identify perioperative myocardial injury and its extent because it directly affects postoperative outcome. Further, the assessment of such injury is helpful to compare different methods of myocardial protection and will be useful in perioperative management of patients. AIM OF THE STUDY: Our prospective study was thus designed to analyse the correlation between postoperative outcomes and Troponin-T level and to find out if there is any positive correlation between Aortic cross clamp time and Troponin-T. If there is definite positive correlation between aortic cross clamp time and Troponin-T levels and between postoperative outcomes and Troponin-T levels, that becomes a definite evidence that this test is a viable and effective test in cardiac surgical field to assess the extent of myocardial ischemic injury. MATERIALS AND METHODS: This prospective study was undertaken as an analytical study to find out the significance of post-operative Troponin-T level as a marker of myocardial ischemic injury in mitral replacement surgeries, in cardiothoracic surgery department of Rajiv Gandhi Government General Hospital, Chennai-600003, from April 2012 to March 2013. Hospital Ethical Committee approved this study to be conducted in Rajiv Gandhi Govt. General Hospital. Patients were well informed about the nature of the study and consent was obtained in written format for withdrawal of 2 ml of blood and Troponin-T estimation. INCLUSION CRITERIA: Patients who were to undergo Mitral Valve Replacement Surgeries during the above said period were included in the study. Both Rheumatic and Non-rheumatic pathologies were accepted for the study. Both stenotic (MS) and regurgitant (MR) lesions (or a combined of two) were included. Only patients aged more than 13 years were included in the study. EXCLUSION CRITERIA: 1. Patients who have evidence of coronary artery disease, 2. Re-do mitral valve surgeries (Post-CMC), 3. Poor left ventricular function (EF<40%), 4. LV diastolic dimension >7.0 cm, 5. Renal failure, 6. Hepatic failure, 7. Patients with more than mild AR (aortic regurgitation). DISCUSSION: Though this study was done with limited number of patients, it clearly shows that prolonged cross clamp time is associated with elevated Troponin-T values and that elevated Troponin-T values are associated (significant association) with increased morbidity in the form of prolonged ventilatory support, prolonged inotropic support, requirement of high doses of inotropes, postoperative cardiac failure and poor ventricular ejection fraction. The per-operative variables that are associated (significantly) with high levels of Troponin-T are 1. Prolonged cross clamp time (more than 70 minutes), 2. Prolonged CPB time (>90 minutes) and 3. Prolonged CP time (>25 minutes between 2 cardioplegia doses). By ROC curve analysis, the cut-off value of Troponin-T, was derived, above which the morbidity is significantly increased. The cut-off value is 0.6 ng/ml. (In a study conducted by Bernard l. Croal et al, with 1365 patients, and published in “Circulation” Journal, 2006;114:1468-1475, the cut-off value derived by ROC curve analysis, was 0.46 ng/ml and it was proved that the mortality significantly increased above this value). In this study, Troponin-T levels show good correlation with aortic cross clamp time, CPB duration and prolonged CP interval as well as postoperative variables like prolonged inotropic supports, high dose inotropes, prolonged ventilation and reduced LV function (poor EF). Hence, it is clear that Troponin-T is a good tool to assess the adequacy of myocardial protection. CONCLUSION: Troponin-T is a reliable indicator of extent of myocardial injury in cardiac surgical patients and is a good armamentarium in the pool of diagnostics in cardiothoracic surgical field. This test should be used more often than now, in postoperative period, to assess the adequacy of myocardial protection. This will have two important implications. 1. In an individual patient, who is hemodynamically unstable in the postoperative period, this test is helpful, in defining the cause of it. 2. The efficiency of different techniques of myocardial protection may be compared with one another, based on Troponin-T levels.
| Item Type: | Thesis (Masters) |
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| Additional Information: | Reg.No.18101001 |
| Uncontrolled Keywords: | Post operative Troponin-T level, myocardial ischemic injury, mitral Valve replacement surgeries. |
| Subjects: | MEDICAL > Cardio Vascular and Thoracic Surgery |
| Depositing User: | Subramani R |
| Date Deposited: | 11 Feb 2020 02:35 |
| Last Modified: | 24 Aug 2020 04:50 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/11908 |
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