CABG Patency Assessment & Surgical Training: To Measure Is To Know!

Cardiac Surgery
CABG Patency Assessment & Surgical
Training: To Measure Is To Know!
Use of Flow Assessment to
Develop Surgical Expertise
Patency of a coronary bypass graft anastomosis is
critical to successful coronary artery bypass surgery.
Mastery in sewing an error-free anastomosis
is a basic requirement for all cardiothoracic or
vascular residents. Over the past decade, numerous
cerebrovascular and microsurgical workshops
have relied on on-the-spot quantitative blood
flow measurements with Transonic transit time
ultrasound flowprobes to verify the patency of a
newly sewn anastomosis and/or test the surgical
proficiency of a workshop participant.
By measuring volume flow with a transit-time
ultrasound flowprobe, workshop students, whether
they are residents learning the skill for the first
time, or fellows or surgeons perfecting their sewing
skills, can tell immediately if the graft exhibits
technical error. The trainer/director also has an
opportunity to assess the progress of students
during the course of the workshop. One workshop
director advises having a student measure flow
through an anastomosis at the beginning of a
workshop, halfway through the course and at the
end of the workship to demonstrate mastery of the
skill.
This ability to correct otherwise undetectable flow
restrictions, on the spot, after constructing bypass
grafts is also invaluable in the operating room
during on or off pump CABG where measuring
blood flow assures the surgeon that vessels are
patent and adequate coronary flow is restored
after a bypass has been constructed. Flow
assessment can:
1.
Verify graft patency
2.
Reduce bring-backs
3.
Improve patient outcomes
FlowAssessmentduring ResidencyTraining(CV-25-tn)RevA2015USltr
At the top of the screen, the AureFlo real-time display shows
a LIMA-LAD volume flow waveform (systolic flow volume in
red; diastolic flow in blue). The bottom trace is an ECG. Also
displayed on the monitor are mean flow in mL/min, pulsatility
index, D/S Ratio or DF%, ECG tracing and heart rate.
AureFlo® Real-time Display Transonic’s AureFlo® system provides this vital information instantaneously on a real-time display. A quick
glance at the AureFlo will tell the surgeon
the mean flow through a bypass graft and if
the graft has a characteristic pulsatile waveform. By following the time-tested Transonic
protocol (see back side), a surgeon can decide immediately whether to give Protamine
and close, or revise an anastomosis.
Cardiac Surgery
Coronary Graft Patency Assessment Protocol
Measure Graft Flow
Evaluate Mean Flow Reading
Questionable
or Poor Flow
< 15 mL/min
(per mean flow chart)
Examine Graft
(spasm/kinks/twists/soft BP)
Good Flow
> 20 mL/min or > 30 mL/min
(depending on a patient’s
size and physiology)
Remeasure Graft Flow
with native coronary artery occluded
(mean flow reading & waveform printout)
Good Flow
Reevaluate Mean Flow Reading
(per mean flow chart)
Acceptable Flow
Profile
Poor Flow
< 5 mL/min
Questionable Flow
Flow Waveform Analysis
• Acceptable Flow Profile:
• Diastolic Dominant (left ventricle)
• Systolic/Diastolic balanced (right ventricle)
• Acceptable Pulsatility Index (1 - 5)
Acceptable
Graft
Questionable Flow Profile
Analyze Other Factors
• Small patient/small target vessel?
• Physiologic factors (MI, vasospasm, low MAP)?
• Poor runoff?
• Quality of myocardium?
Suspect Graft
Patent Graft
Proceed to measure flow in next graft
FlowAssessmentduring ResidencyTraining(CV-25-tn)RevA2015USltr
Examine Graft for Anastomotic Error
Revise graft