Intraoperative Coronary Graft Quality Assessment �

DR. MOHAMED ELAWADI

PROF. OF CARDIOTHORACIC SURGERY

WHY WE NEED IT

• PREOPERATIVE SENARIOES
• OPERATIVE SENARIOES
• POSTOPERATIVE SENARIOES

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• INTRAOPERATIVE TEE ??
• ECG??
• Failed bypass grafts may exist without any intraoperative sign, including hemodynamic instability, electrocardiographic signs of myocardial infarction and/or new regional wall abnormalities seen on Transesophageal Echocardiography. 

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Transit-time flow measurement (TTFM)

Epicardial Ultrasound (ECUS) Techniques

Transit-time flow measurement (TTFM)

• The basics of TTFM are easy to learn.
• Parameters for acceptable bypass graft function are: flow >15 c/min, Pulsatility Index (PI) <5.0 for acceptable graft; <3.0 for ideal value and diastolic filling 60–80% for left-sided vessels and 45–55% for right sided vessels .

WHEN TO MEASURE

• ON PUMP CABG
• On pump
• AFTER CROSS CLAMP OFF
• POST-PROTAMINE
• OFF PUMP CABG
• After extra sutures.

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Where to measure

• It is best to measure flows near as possible to the distal anastomosis, as this is more likely to reflect the flow into the coronary bed.
• Measurement far from the distal anastomosis also incorporates the resistance conferred by the length of the conduit.
• However, for a marginal artery graft on the posterior surface of the heart, after off-pump, this may not be possible.
• In this instance, measurements are taken where convenient for non-displacement of the heart, near the aortic origin of a free graft or near the inflow as for the proximal RIMA travelling through the transverse sinus to the circumflex system.
• However, one must appreciate that measurement at the ‘far end’ of a graft may have systemic arterial pressure aspects with wave forms reflective of this systemic pressure .

•  TTFM values with low flow and high PI accurately predict the likelihood of graft occlusion (the True positive).
•   A false positive (i.e., a good graft with high PI) rarely occurs and is most often due to improper probe placement or competitive flow .
• The specificity of TTFM (i.e., the ability to predict a good graft, or ‘true negative’) is 98.4%

TRUE NEGATIVE

EXTRA STITCHES

CHANGE FLOW AFTER 24 HOURS

DRAWBACKS

• SIZING OF THE PROBE.
• SEQUENTIAL ANASTOMOSIS.
• QUALITY OF NATIVE CORONARY ARTERIES.
• MATCHIG THE SIZE OF THE GRAFT AND NATIVE CORONARIES.
• ANGLE OF PROBE.

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Epicardial Ultrasound (ECUS) Techniques

• ECUS assessment of distal anatomises perform a color angiogram intraoperatively at a time when a bypass graft can be revised at minimal cost to the patient

� It can be used to evaluate a conduit pre- and post-harvest for detection of an ITA dissection

��The ascending Aorta for soft non-palpable atherosclerotic plaque

Absence of Aortic dissection after de-cannulation of the aortic cannula

��Determine the depth of a coronary artery below the Epicardium, in intramyocardial artery

FUTURE

• STUDYING NATIVE FLOW FOR BETTER UNDERSTAND OF CORONARY FLOW AND WHICH VESSEL SHOULD BE GFRAFTED OR EVEN STENTED.

CONCLUSION

• TTFM and ECUS help surgeons to see the imperfect graft at a time when revision does the least harm to patients

���������THANK YOU