الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Abnormal ventricular diastolic function can cause clinical heart failure (HF) in 40 to 50% of patients despite having normal systolic function and the situation is more alarming because the incidence of diastolic HF increases with age, approaching 50% in patients over 70 years of age. Diastolic dysfunction may increase the postoperative morbidity and mortality thus giving rise to enormous rise in health care budgets.
Clinically, diastolic dysfunction is measured both by transthoracic echocardiography and transesophageal echocardiography. Conventionally, transmitral pulsed wave Doppler and pulmonary venous Doppler are used to identify diastolic dysfunction. However, the major disadvantages of these techniques are their dependence on left ventricular loading conditions. These limitations have led to the development of newer Doppler techniques of color M-mode Doppler and tissue Doppler which can assess diastolic dysfunction independent of preload conditions.
The aim of this study is to evaluate and compare the effects of isoflurane, sevoflurane and propofol (study drugs) on left ventricular (LV) diastolic function in patients with impaired LV relaxation due to ischemic heart disease undergoing on pump CABG using transesophageal echocardiography.
We studied 90 patients scheduled for CABG surgery. Patients were selected by a preoperative TTE diagnosis of grade 1 diastolic dysfunction. Patients were randomly divided by closed envelope method into three groups: (Group A) received 100-200 μg/kg/min 0f propofol for maintenance during surgery (propofol group; n=30). (Group B) received
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1 MAC of isoflurane for maintenance during surgery (isoflurane group; n=30) and (Group C) received 1 MAC of sevoflurane for maintenance during surgery (sevoflurane group; n=30).
After preoxygenation, intravenous induction of general anesthesia was performed using midazolam 0.05 mg/kg, fentanyl 5 - 10 micg/kg and propofol 2-3 mg/kg (titration guided by hemodynamics). Endotracheal intubation was performed using pancuronium bromide 0.1 mg/kg.
Five min after induction of anesthesia, propofol infusion was continued at a rate 100-200 μg/kg/min in group A. propofol administration was stopped in group B and C. isoflurane was administered at 1 MAC end-tidal concentration in group B and sevoflurane was administered at 1 MAC end tidal concentration in group C, In all groups, fentanyl was administered at a rate of 1-2 μ/kg/hr.
For hemodynamic measurements, heart rate (HR), systolic, diastolic and mean arterial pressures (SBP, DBP and MAP) along with central venous pressures (CVP). The pressure transducers were zeroed against atmospheric pressure, maintained and recorded at the midaxillary level throughout the operation. All pressure recordings were carried out in the expiratory phase.
Heart rate (HR), mean arterial blood pressure (MAP) and central venous pressure (CVP) were measured for statistical analysis before induction of anesthesia (after insertion of all monitors) as baseline reading, after sternotomy, after opening pericardium, before aortic cannulation and twenty minutes after going off bypass. Bispectral index (BIS) was recorded after induction of anesthesia and before skin incision
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as baseline reading, after sternotomy, after opening pericardium, before aortic cannulation and twenty minutes after going off bypass.
All echocardiography measurements for statistical analysis were performed one hour before going to surgery as a baseline reading by (TTE), after sternotomy by (TEE), after opening pericardium, before aortic cannulation By (TEE) and twenty minutes after going off bypass by (TEE). Complete TEE examination was performed and LV diastolic function was assessed by using three modalities; trans mitral flow velocity profile, pulmonary vein flow velocity profile and tissue Doppler imaging (TDI) of the mitral annulus.
For the transmitral flow velocity profile E wave, A wave and E/A ratio and the deceleration time of early diastolic filling were measured by pulsed wave Doppler (PWD). For the pulmonary vein flow velocity profile peak systolic velocity (S), peak diastolic velocity (D), peak reverse atrial velocity (A) and S/D ratio were recorded. For tissue velocity recording Em, Am and Em/Am were recorded.
There were insignificant differences between the patients of the studied groups according to age and other demographic parameters (BMI and sex) which can affect diastolic function. Also there were insignificant differences between the patients of the studied groups according to MAP, HR, BIS and CVP which can affect mitral inflow pattern.
There were insignificant differences according to the amount of fentanyl, midazolam used through the surgery (which can interfere with the studied drugs’ effect on diastolic function) and in the amount of phenylehperine used which can affect the systemic vascular resistance that can influence the readings.
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There were high significant increases in (E/A, Em/Am) ratios and high significant decreases in (DT, IVRT) times and S/D ratio in isoflurane and sevoflurane groups after sternotomy and after pericardial opening in relation to baseline (with no significant difference between them) and there were insignificant increases in (E/A, Em/Am) ratios and insignificant decreases in (DT, IVRT) times and S/D ratio in propofol group.
Twenty minutes after going off bypass there was statistically high significant increases in (E/A, Em/Am) ratios and high significant decreases in (DT, IVRT) times and S/D ratio in isoflurane and sevoflurane groups in relation to baseline, but in propofol group there was statistically high significant decreases in (E/A, Em/Am) ratios and high significant increases in (DT, IVRT) times and in S/D ratio relation to baseline.
Conclusion
1- Isoflurane and sevoflurane improve the diastolic dysfunction after sternotomy and after pericardial opening in relation to baseline values with no significant differences between them.
2- The improvement caused by propofol after sternotomy and after pericardial opening in relation to baseline is that of a magnitude that is unlikely to cause clinical effect.
3- Twenty minutes after going off bypass, diastolic dysfunction is improved in relation to baseline values in isoflurane and sevoflurane groups and it gets worse in propofol group.