الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
C
oronary artery bypass surgery (CABG) has contributed to an increase in survival, quality of life and life expectancy. The anastomotic quality and graft patency is directly associated with both early and long-term clinical results after CABG. It is a complication that can lead to refractory angina, myocardial infarction, arrhythmias, and even mortality. Although most surgeons believe it to be a rare occurrence, the incidence of perioperative graft failure has been estimated to be from 5 to 11%. It was traditionally common for surgeons to determine the adequacy of anastomosis by crude evaluation such as palpitation of graft pulsation, to assess hemodynamic stability and electrocardiographic chances. But this method is unreliable and indirect. Therefore, it is critical for surgeons to directly evaluate the quality of anastomosis in CABG.
To increase the reliability of the graft patency several methods have been introduced over the last decade including coronary angiography, fluorescence imaging, CT angiography, Magnetic Resonance Imaging (MRI) and TTFM. Transit time flow measurement (TTFM) has been reported to be a suitable method for easy and quick intraoperative functional assessment of bypass grafts, independent of vessel size and shape. Recently 20% of cardiac surgeons use TTFM to assess the graft. Since 2010.
This study was aiming to evaluate the effect of use of TTFM on the outcome of CABG operations and it was carried out on 40 patients and examined 119 grafts, we use inotropic agents to maintain the systolic pressure at 90- 100 mmHg if the blood pressure was lower than that limit. TTFM was performed for assessment of every graft after completion of anastomosis during operation by using a transit time flow meter (MediStim MQ), and all measurements were repeated before the closure of the sternum. The TTFM probe was perfectly fitted around the graft. When necessary, different probes, which fit the actual size of the vessel were used to avoid compression of the graft. LIMA was pedicled Skeletonization of a small segment of the mammary artery was necessary to reduce the quantity of the tissue interposed between the vessel and the probe. Flow through the whole sequential bypass and flows through the both proximal segment of graft were examined. The device displays a flow curve and calculates the mean flow (ml/min), pulsatile index (PI). In case of the PI > 5 it was an indicator of poor flow. The mean flow was not used alone as an indicator of poor flow, and it was evaluated together with the (PI) Interpretation of the values obtained together with the preoperative angiographic pictures (i.e quality of the native vessel and its vascular bed) has allowed us to reach a decision whether or not to revise a graft. In case of unsatisfactory TTFM findings, the length and property of the graft was checked. It was also checked for twisting, kinking, dissection, stretching and spasm. If one of them was detected it was corrected. All measurements were repeated before the closure of the sternum to confirm graft patency and to detect any possible new graft kinking or compression even if satisfactory TTFM findings were obtained in the last measurement.
TTFM data was described as two main readings which are MF in ml/min (mean flow), PI (pulsatility index) and it was measured for the all types of the grafts. In MF it was the highest in AO-OM system (34.5 ± 18.46) followed by LIMA-LAD system (33.0 ± 19.65) then AO-Diagonal (31.0 ± 26.38) and lastly AO-RCA(29.50 ± 32.22). For the PI the lowest measurements was 0.8 and it was for both LIMA to LAD and then 1.2 for AO-OM system and 1.4 for AO-DIAG system and 1.8 for AO-RCA system
The most important finding in this study which represents the usefulness of the usage of TTFM is how much grafts needed to be revised according to the grafts measurements and it was only 6 grafts in 6 patients (one grafts for each patient) among 40 patients which account for 15%. from total number of patients and account for about 5% from the total number of grafts (119 grafts). The cause for revision was due to competitive flow in two cases, technical error in two cases and kinking in two cases.