The Effects of Dexmedetomidine on Myocardial Function Assessed by Tissue Doppler Echocardiography During General Anesthesia in Patients With Diastolic Dysfunction

Dexmedetomidine is a commonly used sedative and adjuvant agent to general anesthesia. The present was designed to evaluate the effects of dexmedetomidine on myocardial function by using tissue Doppler echocardiography during general anesthesia in patients with diastolic dysfunction. Forty patients undergoing orthostatic surgery with ejection fraction preserved diastolic dysfunction grade 2 or 3 were randomly allocated to the Control and Dex group (n1⁄4 20, each). In the Dex group, dexmedetomidine was given as an initial loading dose of 1.0mg/kg over 10 minutes followed by a maintenance dose of 0.5mg/kg/h. The ratio of peak early diastolic transmitral or transtricuspid inflow velocity to early diastolic mitral or tricuspid annular velocity (LV or RV E/e0) and left or right ventricular myocardial performance index (LV or RV MPI) were measured at before and after the administration dexmedetomidine or saline. The Dex group showed significant decrease of heart rate (P1⁄4 0.038), and increase of mean blood pressure (P< 0.001), LV E/e0 (P1⁄4 0.025), and LV MPI (P< 0.001) compared to those of the Control group on a linear mixed model analysis. Also, the Dex group showed significant increase of RV E/e0 (P< 0.001) and RV MPI (P1⁄4 0.028) compared to those of the Control group. Intraoperative dexmedetomidine administration during general anesthesia was appeared to deteriorate biventricular function in patients with diastolic dysfunction. We suggest careful consideration and a need for reducing dosage when administrating dexmedetomidine in patients with diastolic dysfunction. , Namo Kim, MD MD, ung Jun Oh, MD, PhD heart rate, LV = left ventricle, MBP = mean blood pressure, MPI = myocardial performance index, MV e0 = peak early diastolic mitral annular velocity, MV s0 = peak systolic mitral annular velocity, RV = right ventricle, TAPSE = tricuspid annular plane systolic excursion, TV E = peak early diastolic transtricuspid inflow velocity, TV e0 = peak early diastolic tricuspid annular velocity, TV s0 = peak systolic tricuspid annular velocity. INTRODUCTION D exmedetomidine is a highly selective a2-adrenoreceptor agonist that has gained popularity in the intensive care unit, cardiovascular intervention and endoscopic procedures, and as an adjuvant to general anesthesia for its sedative and analgesic effects. Although there have been studies suggesting the use of perioperative dexmedetomidine in cardiac surgery improved postoperative morbidity and mortality, there is also conflict in literature that have reported adverse cardiovascular effects of dexmedetomidine including hypotension or hypertension, bradycardia, and even cardiac arrest. Even with the amounting evidence that dexmedetomidine has critical cardiovascular effects, few studies have investigated the direct effects of dexmedetomidine on cardiac function. Although our previous study presented evidence that dexmedetomidine administration had minimal effects on cardiac function in young healthy patients, there are no current studies assessing the effects of dexmedetomidine administration on biventricular function in patients with cardiac dysfunction. In a recent study, 64.1% of patients over 65 years were assessed with diastolic dysfunction. Regardless, the importance of diastolic dysfunction has been underestimated in comparison to systolic dysfunction. Because preoperative diastolic dysfunction is highly affiliated with overall postoperative prognosis, mortality after acute coronary syndrome, and adverse postoperative outcome of patients with myocardial infarction, undermining diastolic dysfunction may be a critical mistake. As dexmedetomidine becomes a more ubiquitous agent in the clinical field, we believe a true evaluation of dexmedetomidine on cardiac function in patients with cardiac dysfunction is critically essential. Tissue Doppler indices are more reliable in estimating cardiac function than 2-dimensional or conventional Doppler echocardiography in patients with preexisting left ventricle (LV) relaxation impairment. The ratio (E/e0) of peak early diastolic transvalvular inflow velocity (E) to early diastolic valvular annular velocity (e0) is a valuable tool in diagnosing diastolic dysfunction independent of preload, in patients with preserved F) and impaired LV relaxation. Tissue ed myocardial performance index (MPI), ystolic and diastolic performance to www.md-journal.com | 1 evaluate global cardiac function. Its most prominent use is to assess diastolic function. In contrast to Doppler-assessed transvalvular blood flow, tissue Doppler imaging derived MPI is relatively independent of heart rate (HR) and loading conditions. In this randomized, double-blind, and placebo-controlled trial, we investigated the effects of dexmedetomidine on myocardial function in patients with diastolic dysfunction by using tissue Doppler imaging derived indices including MPI and E/e0 during general anesthesia.