الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Coronary 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 100 patients and examined 282 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 LIMALAD 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 14 grafts in 14 patients (one grafts for
each patient) among 100 patients which account for 14%. from
total number of patients and account for about 5% from the
total number of grafts (282 grafts). The cause for revision was
due to graft kinking in five cases, Extra hemostatic stitch to
control bleeding distal anastomosis causing abnormal TTFM
parameters which occurred in two cases, small caliber and bad
quality vein was occurred in two cases, spastic LIMA graft was
occurred in two cases, poor targets was occurred in two cases
amd competitive flow in two cases.