Vascular endothelial growth factor release following coronary artery bypass surgery: extracorporeal circulation
P B Burton1, V J Owen, S Hafizi
1Cardiothoracic Surgery, Imperial College School of Medicine at the National Heart and Lung Institute, London, U.K.
Insights
Coronary artery bypass graft surgery, particularly with cardiopulmonary bypass, significantly increases vascular endothelial growth factor (VEGF) levels. This suggests myocardial ischemia during surgery stimulates VEGF production, potentially impacting graft healing and blood flow.
Area of Science:
- Cardiovascular Surgery
- Molecular Biology
- Biochemistry
Background:
- Vascular Endothelial Growth Factor (VEGF) offers cardioprotection and promotes angiogenesis, beneficial for coronary artery bypass graft (CABG) surgery.
- The impact of surgical ischemia on VEGF production remains largely unknown.
Purpose of the Study:
- To investigate circulating VEGF levels after CABG using standard cardiopulmonary bypass (CPB-CABG) versus the off-pump 'octopus technique' (OP-CABG).
- To explore the role of hypoxia in stimulating VEGF release from cardiac myocytes.
Main Methods:
- Serum VEGF levels were measured in patients undergoing CPB-CABG (n=20), OP-CABG (n=12), and non-cardiac surgery (n=6) at various postoperative times.
- In vitro experiments assessed VEGF release from neonatal rat cardiac myocytes under hypoxic conditions.
Main Results:
- VEGF levels significantly increased postoperatively in both CPB-CABG and OP-CABG groups, peaking at 24 hours.
- OP-CABG showed higher VEGF levels compared to CPB-CABG at multiple time points.
- Non-cardiac surgery did not elevate VEGF levels. Hypoxia in vitro stimulated VEGF release from cardiac myocytes.
Conclusions:
- Myocardial ischemia during both CPB-CABG and OP-CABG potent stimulates VEGF production.
- Elevated postoperative VEGF may influence graft endothelialization and cardiovascular hemodynamics.
Aims:
The aim of this study was to examine the circulating levels of vascular endothelial growth factor, following coronary artery bypass graft surgery performed using both standard cardiopulmonary bypass or the 'octopus technique' on the beating heart.
Background:
Vascular endothelial growth factor has a number of effects that are beneficial in the setting of coronary artery bypass graft surgery including cardioprotection, potent angiogenic activity and amelioration of intimal hyperplasia. Hypoxia is a powerful stimulator of vascular endothelial growth factor expression yet the ability of ischaemia, occurring during coronary artery bypass graft surgery, to induce vascular endothelial growth factor production is unknown.
Methods And Results:
Serum vascular endothelial growth factor levels were determined in patients undergoing coronary artery bypass graft surgery with standard cardiopulmonary bypass (CPB-CABG group; n=20), with off-pump coronary artery bypass; (OP-CABG; n=12) and in patients undergoing non-cardiac major surgery (n=6). The effect of hypoxia on vascular endothelial growth factor release by neonatal rat cardiac myocytes in vitro was studied. In the CPB-CABG group vascular endothelial growth factor levels were significantly increased to 78.5+/-39.3 and 110.5+/-16.3 pg. microl(-1)8 and 24 h post-operatively, declining to 14.9+/-9.9 pg. microl(-1)by 48 h to pre-operative values (14.4+/-8.6 pg. microl(-1)). Significantly higher vascular endothelial growth factor levels were also present in the OP-CABG group 3, 6 and 24 h post-operatively (levels 136. 6+/-29.3, 143+/-26.12 pg. microl(-1)and 93.5+/-20.1 pg. microl(-1), respectively). However, non-cardiac major surgery did not result in elevated vascular endothelial growth factor levels post-operatively (46.36+/-9.76 vs pre-surgery levels of 26.84+/-6.1 pg. microl(-1)). Either 15 min or 3 h of hypoxia stimulated vascular endothelial growth factor release from neonatal rat cardiac myocytes in vitro. Twenty-four and 48 h post hypoxia, levels of vascular endothelial growth factor were significantly elevated by approximately 17.5- and 48.5-fold respectively.
Conclusions:
These data demonstrate myocardial ischaemia secondary to CPB-CABG and OP-CABG to be a potent stimulator of vascular endothelial growth factor production, which may have implications for graft endothelialization and cardiovascular haemodynamics post-operatively.
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