Discussion
Likely mechanisms of intra-mural haematoma in this case include surgical trauma perioperatively or trauma/bruising to the graft from cardiac massage during the CALS protocol. We routinely use skeletonized mammary arteries for CABG. Intra-operative surgical trauma seemed unlikely as there was no visible evidence of damage to the conduit during the operation. An evolving haematoma would more likely present as progressive regional ischaemia on ECG with segmental wall motion abnormality on echocardiogram. There were no ischaemic changes on ECG post-operatively. This patient had no regional wall motion abnormality on post-cardiopulmonary bypass transoesophageal echocardiogram (TOE). Post-resuscitation TOE showed global LV impairment after stabilisation on VA-ECMO. It could be that the cardiac arrest 2hrs after surgery was unrelated to the intramural haematoma and the haematoma was as a result of cardiac massage during CPR.
A much more common cause of early graft failure (failure within 1 month of surgery) is technical failure or thrombosis which is usually at the site of the anastomosis. LHC and OCT showed that all anastomoses were intact with good flow and no sign of intra-lumnal thrombosis.
OCT is a catheter based invasive imaging system which allows for high-resolution imaging of intra-luminal and trans-mural coronary structures thus overcoming many of the limitations of angiography. Using light rather than ultrasound, OCT produces high-resolution in-vivo images of coronary arteries and deployed stents.
Accumulating data support a clinical role for OCT in a multitude of clinical scenarios, including assessing the natural history of atherosclerosis and modulating effects of therapies, mechanisms of acute coronary syndromes, mechanistic insights into the effects of novel interventional devices, and optimization of percutaneous coronary intervention. We have found no previous reports of the use of OCT to evaluate conduit post-CABG. Potential risks from the procedure include that it can cause intimal dissection in fresh conduit.
Should OCT be used to routinely evaluate all conduit post-op? We can advocate its usage when the LHC findings are unclear.
OCT to complement LHC can be a valuable tool to evaluate conduit post CABG. The absence of proximal aortic anastomoses in total arterial re-vascularization reduces the risk of graft disruption when early post-operative LHC/OCT is indicated.