Introduction: The aim of the present study was to evaluate myocardial function using Tissue Doppler echocardiography imaging during high thoracic epidural analgesia (HTEA) before coronary artery bypass graft surgery (CABG). HTEA of the segments Th1-4 attenuates the sympathetic response during coronary heart surgery, and is believed to reduce the risk of perioperative myocardial ischaemia and to improve left ventricular (LV) function. Tissue Doppler derived modalities have appeared promising for detailed information on systolic and diastolic myocardial function . Tissue tracking, a Tissue Doppler based modality, depicts the myocardial baso-apical displacement, which correlates with global left ventricular function . We therefore hypothesized that tissue tracking would detect changes in myocardial performance during test and induction of HTEA.
Method: Six patients, one female and five male, scheduled for elective CABG, were included in the study after having signed informed consent. An epidural catheter (Th1-2 or 2-3) was inserted the day before surgery. On the day of surgery, the patients underwent transthoracic echocardiography (TTE) immediately before catheter test with 3 mL of lidocaine/epinephrine 2% and further induction of analgesia with 7 mL of bupivacaine (4.75 mg/mL)/sufentanil (2.5 μg/mL). Analgesia from Th1 to Th10 was achieved after 20 minutes, and TTE thereafter repeated before induction of standardized general anaesthesia. All recordings were carried out using Vivid-7 echocardiography technology with activated Tissue Doppler and high frame rate >216 frames per second. Data were post-processed for assessment of tissue tracking using dedicated software. Regional systolic displacement in the apical longitudinal axis was quantified for the basal septal segment before and after induction of HTEA.
Results: 5 of 6 patients demonstrated increased basal septal displacement after HTEA, in an average range from 1.63-3.09 mm. In one patient displacement decreased after induction of analgesia. All but one had normal or nearly normal ejection fraction (EF) before HTEA. The one patient with reduced EF of 35% had evident reduced displacement before induction, which further diminished after induction of HTEA.
Discussion: Tissue tracking seems to demonstrate increased septal displacement after HTEA. This increment may reflect improved contractility of longitudinal myocardial fibres in response to reduced afterload and/or enhanced myocardial oxygen supply. Tissue tracking is a very easy manageable method, which allows rapid objective assessment of regional myocardial displacement. The possible role of tissue tracking and other Tissue Doppler modalities in perioperative monitoring of myocardial performance depend on future studies.
1 D'hooge J, Heimdal A, Jamal F, et al. Regional strain and strain rate measurements by cardiac ultrasound: principles, implementation and limitation. Eur. J Echocardiogr
2 Pan C, Hoffmann R, Kuhl H, et al. Tissue tracking allows rapid and accurate visual evaluation of left ventricular function. Eur J Echocardiogr