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When and how to shunt the coronary circulation in off-pump coronary artery bypass grafting
E E van Aarnhem1, A P Nierich, E W Jansen
1Department of Cardiopulmonary Surgery, Heart-Lung Institute, Utrecht University Hospital, The Netherlands.
Insights
Temporary coronary artery occlusion during off-pump CABG is effective. Critical ischemia is rare, especially with shunting, avoiding bypass and myocardial infarction.
Area of Science:
- Cardiovascular Surgery
- Cardiac Anesthesia
- Vascular Surgery
Background:
- Off-pump coronary artery bypass (CABG) surgery aims to reduce complications associated with cardiopulmonary bypass.
- Temporary coronary artery occlusion is a technique used for anastomosis construction in beating heart CABG.
- Assessing the safety and efficacy of this technique is crucial for surgical practice.
Purpose of the Study:
- To evaluate the consequences of temporary coronary artery occlusion during off-pump CABG.
- To determine the incidence of myocardial ischemia, hemodynamic instability, and need for conversion to cardiopulmonary bypass.
- To assess the effectiveness of a temporary aorto-coronary shunt in managing critical ischemia.
Main Methods:
- A study involving 200 patients undergoing off-pump CABG with 365 distal anastomoses.
- Patients received pre-treatment with calcium antagonists, beta-blockade, and thoracic epidural blockade.
- Myocardial ischemia was defined by S-T segment elevation, and a temporary aorto-coronary shunt was used for critical ischemia.
Main Results:
- Ischemia occurred in 10% of temporary occlusions, predominantly in the right coronary artery (RCA).
- Critical ischemia, leading to severe hypotension, occurred in 5 patients with non-occlusive disease.
- The temporary aorto-coronary shunt effectively normalized parameters within 30 seconds, allowing procedures to continue uneventfully without peri-operative infarctions.
Conclusions:
- Temporary segmental occlusion is a safe and effective method for anastomosis in off-pump CABG.
- Critical ischemia is infrequent and primarily associated with RCA and non-occlusive disease.
- Temporary aorto-coronary shunting is a valuable tool to prevent conversion to cardiopulmonary bypass and myocardial infarction.
Objective:
To assess the sequelae of temporary coronary artery occlusion in off-pump, beating heart CABG, i.e. ischemia, hemodynamic instability and the need for conversion to cardiopulmonary bypass.
Methods:
In 200 patients (150 male), mean age 60 (range 35-81) years, 365 distal anastomoses were performed, i.e. 1.8 anastomoses per patient through limited and full access. One hundred seventy six LAD, 61 diagonal, 71 RCA, 7 RPD and 50 circumflex branches were grafted. Patients were pretreated with calcium antagonists, long-acting beta-blockade and had thoracic epidural blockade. The anastomosis was constructed using two microvascular clamps, preceded by ischemic preconditioning in non-occlusive disease. Myocardial ischemia was defined as > 1 mm S-T segment elevation. A simple aorto-coronary shunt, consisting of two intravenous catheters and a 10 cm connecting tube (flow > 20 ml/min), was used in critical ischemia.
Results:
Ischemia occurred during 35 (10%) temporary coronary artery occlusions. Fifteen of these (43%) were RCA. In five of these 15 patients, all with non-occlusive disease, critical ischemia occurred with bradycardia, third-degree heart block and subsequently severe hypotension, which normally requires conversion to cardio-pulmonary bypass. Following introduction of the shunt (4 patients) electrocardiographic and hemodynamic parameters normalized within 30 s. The off-pump procedures could be continued uneventfully. There were no peri-operative infarctions.
Conclusion:
Temporary segmental occlusion is an effective method for anastomosis suturing in off-pump, beating heart CABG. Critical ischemia was observed rarely, only in the RCA and in non-occlusive disease. Temporary aorto-coronary shunting could avoid conversion to cardiopulmonary bypass and myocardial infarction.