Is There a Relationship Between TP-e/QT Ratio and Spinal Anesthesia-Related Cardiovascular Events in Pregnant Women?

Abstract

Introduction and Objective: Prolonged TPe interval has been reported to reflect the abnormal distribution of ventricular repolarization which can be used as a marker of ventricular arrhythmias. Since prolonged TPe/QT ratio is associated with cardiac pathologies, it is thought that it may also be associated with cardiovascular adverse events that occur during and after spinal anesthesia. The aim of this study is to investigate whether there is a relationship between prolonged TPe/QT ratio, which is routine preoperative non-invasive patient data that can be evaluated easily, and perioperative adverse cardiovascular events during cesarean section in pregnant women undergoing spinal anesthesia.
 Materials and Methods: Voluntary consent was obtained for our study in which 144 pregnant women who were planned for elective cesarean section were included. QT interval was measured based on the initial point where the Q wave or the R wave in the absence of the Q wave started to the last point where the T wave ended. TPe interval measurement was based on the peak point of the T wave and the end point of the T wave convexity. Lead V5 was primarily used for TPe measurement. TPe/QT ratios were calculated in Microsoft office excel program. Patients' demographic characteristics, heart rate, systolic, diastolic and mean arterial pressures were recorded every five minutes intraoperatively.
 Results: A weak positive correlation was found between the height variable and the Tpe/QT ratio (p=0.022, r=0.191). As the height increased, the TPe/QT ratio increased. Although it did not reach the level of statistical significance, we found that the TPe/QT ratio was longerin cases with intraoperative bradycardia and hypotension than in cases without complications. The TPe/QT ratio was above 0.21 in patients who developed bradycardia and hypotension. Examination of the correlation between the amount of ephedrine use and TPe/QT ratio revealed a weak positive correlation (p=0.012, r=0.208).
 Conclusion: TPe/QT ratio is a novel cardiac marker with high predictive power, is non-invasive, quite inexpensive, and very practical to measure in the early detection of cardiac events, especially arrhythmia. This novel predictive marker can be used in anesthesia practice, preoperative examination and patient follow-up in the intraoperative operating room to predict fatal cardiac arrhythmias or intraoperative hypo/hypertension. 
 Keywords: Spinal anesthesia, pregnancy, TPe/QT ratio, cardiovascular event