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Aortic Valve Replacement – Right Anterior Thoracotomy
Abstracts
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Methodology: A comparative study was performed on all patients having undergone cardiac surgery between April 2008 and January 2016 at our institute (n = 1875, mean age 67 ± 11 years, 75% males). Data for all patients were collected prospectively as part of a national database. Patient demographics and perioperative data were collected. Preoperative renal function was classified as normal renal function (NRF, CrCl > 85 ml/min, 45%), moderate RD (CrCl 50-85 ml/min, 42%), severe RD (CrCl < 50 ml/min, 12%), or patients on renal replacement therapy (RRT; 1.4%). Results: Most commonly performed operations were isolated CABG (52%) and isolated AVR (13%). ICU stay was longer in those with moderate RD (45 ± 78 h; p = 0.049) or severe RD (63 ± 112 h; p = 0.002) or those on RRT (87 ± 78 h; p = 0.004) when compared with those with NRF (39 ± 52 h), as was return to ICU rate (4.5% in severe RD vs 1.4% in NRF, p = 0.044), and prolonged (>4 h) inotropic requirements (37% in RRT vs 13% in NRF, p < 0.001). There was no significant difference amongst groups in postoperative stroke rate. Blood transfusion rate was significantly higher in those with more severe RD (normal, 13%; moderate RD, 24%; severe RD, 40%; RRT, 70%). Return to theatre ranged from 15% in RRT to 4% in NRF (p = 0.002). New postoperative RRT was required in 3.6% of those with severe RD, 0.5% of those with moderate RD, and 0.1% of patients with NRF (p < 0.001). Early mortality was significantly higher in those with more severe RD (normal, 0.4%; moderate RD, 1.5%; severe RD, 2.3%; RRT, 3.7%; p = 0.023). Conclusion: Preoperative RD is associated with worse outcomes following cardiac surgery. http://dx.doi.org/10.1016/j.hlc.2017.03.149 Aortic Valve Replacement – Right Anterior Thoracotomy Hugh Wolfenden, Dr Prince of Wales Randwick, Sydney, NSW, Australia Aortic valve replacement (AVR) has been performed since 1960 via the classic and gold standard approach of mediansternotomy, with excellent results achieved in an increasingly ageing population. Whilst minimal access procedures have been performed since the late 1990s via the superior hemi-sternotomy, this approach did not take off due to the limitations of a sternal fracture. Mini thoracotomy approaches have been performed for many years but required peripheral cannulation and were technically difficult in valve suture tying. Recent technical advances with Cor-Knot and Rapid Deployment Valves have made valve placement much easier. This allows for a conventional AVR to be performed through a less invasive incision whilst maintaining central aortic cannulation. The technique via the right 2nd intercostal space has a short learning curve, is suitable for most patients and keeps the surgeon within their comfort zone. Early experience has been good with notable early return of mobility, and well received by cardiologists. Experience with initial 55 cases will be presented. http://dx.doi.org/10.1016/j.hlc.2017.03.150
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Learning Coronary Anastomosis Quantifying the Process James Wood, Dr ∗ , Fraser Callaghan, Dr, Michael Wilson, Prof, Stuart Grieve, Prof Macquarie University, Sydney, NSW, Australia Purpose: To use computational fluid dynamics (CFD) to quantify flow through coronary anastomoses carried out by trainee surgeons. Methodology: All 24 (2015) RACS Cardiothoracic SET trainees carried out two simulated coronary anastomoses. 2 mm diameter silicone vessels were anastomosed end to side using 7-0 prolene. Each anastomosis was CT scanned. A centre-line was constructed for each of the native and graft vessels using a semi-automatic technique. A fully automatic algorithm then segmented the lumen space, generated a CFD mesh and performed CFD simulations assuming flow rates of 30 and 5 mL/min in the graft and native vessels respectively. Results: Velocity, pressure drop and radius were calculated for each anastomosis. Despite externally similar appearances of the completed anastomoses, lumen constriction, and consequently haemodynamics, varied widely in the group according to SET trainee level: mean (±SD) minimum lumen radius, peak velocity and pressure drop respectively for SET Level: SET2 0.47 ± 0.04 mm, 83.8 ± 17 cm/s, 1.001 ± 0.36 mmHg; SET4: 0.51 ± 0.10 mm, 75.1 ± 33 cm/s, 0.89 ± 0.44 mmHg; SET6: 0.44 ± 0.03 mm, 80 ± 21 cm/s, 0.95 ± 0.36 mmHg. Conclusion: Using CFD we have been able to characterise haemodynamic performance of coronary anastomoses carried out in a training simulation. We believe this will be an important tool to direct training and optimising patient outcomes. http://dx.doi.org/10.1016/j.hlc.2017.03.151 Relationship Between Urinary Oxygen Tension During Cardiopulmonary Bypass and Development of Acute Kidney Injury Michael Zhu, Mr ∗ , Andrew Cochrane, A/Prof/, Julian Smith, Prof/, Gerard Harrop, Mr, Roger Evans, A/Prof/ Department of Surgery, Monash University and Department of Cardiothoracic Surgery, Monash Health, Melbourne, VIC, Australia Purpose: Renal medullary hypoxia may be a common pathway in the development of acute kidney injury (AKI). There are no validated methods to detect medullary hypoxia in patients. However, experimental findings indicate that changes in urinary oxygen tension (UPO2) reflect changes in medullary PO2. Therefore, we evaluated the relationship between intraoperative UPO2 and the development of AKI after cardiopulmonary bypass (CPB). Methods: From January 2015 to July 2016, thirty-five adult patients undergoing on-pump cardiac surgery were prospectively enrolled. UPO2 was continuously recorded
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Methodology: A comparative study was performed on all patients having undergone cardiac surgery between April 2008 and January 2016 at our institute (n = 1875, mean age 67 ± 11 years, 75% males). Data for all patients were collected prospectively as part of a national database. Patient demographics and perioperative data were collected. Preoperative renal function was classified as normal renal function (NRF, CrCl > 85 ml/min, 45%), moderate RD (CrCl 50-85 ml/min, 42%), severe RD (CrCl < 50 ml/min, 12%), or patients on renal replacement therapy (RRT; 1.4%). Results: Most commonly performed operations were isolated CABG (52%) and isolated AVR (13%). ICU stay was longer in those with moderate RD (45 ± 78 h; p = 0.049) or severe RD (63 ± 112 h; p = 0.002) or those on RRT (87 ± 78 h; p = 0.004) when compared with those with NRF (39 ± 52 h), as was return to ICU rate (4.5% in severe RD vs 1.4% in NRF, p = 0.044), and prolonged (>4 h) inotropic requirements (37% in RRT vs 13% in NRF, p < 0.001). There was no significant difference amongst groups in postoperative stroke rate. Blood transfusion rate was significantly higher in those with more severe RD (normal, 13%; moderate RD, 24%; severe RD, 40%; RRT, 70%). Return to theatre ranged from 15% in RRT to 4% in NRF (p = 0.002). New postoperative RRT was required in 3.6% of those with severe RD, 0.5% of those with moderate RD, and 0.1% of patients with NRF (p < 0.001). Early mortality was significantly higher in those with more severe RD (normal, 0.4%; moderate RD, 1.5%; severe RD, 2.3%; RRT, 3.7%; p = 0.023). Conclusion: Preoperative RD is associated with worse outcomes following cardiac surgery. http://dx.doi.org/10.1016/j.hlc.2017.03.149 Aortic Valve Replacement – Right Anterior Thoracotomy Hugh Wolfenden, Dr Prince of Wales Randwick, Sydney, NSW, Australia Aortic valve replacement (AVR) has been performed since 1960 via the classic and gold standard approach of mediansternotomy, with excellent results achieved in an increasingly ageing population. Whilst minimal access procedures have been performed since the late 1990s via the superior hemi-sternotomy, this approach did not take off due to the limitations of a sternal fracture. Mini thoracotomy approaches have been performed for many years but required peripheral cannulation and were technically difficult in valve suture tying. Recent technical advances with Cor-Knot and Rapid Deployment Valves have made valve placement much easier. This allows for a conventional AVR to be performed through a less invasive incision whilst maintaining central aortic cannulation. The technique via the right 2nd intercostal space has a short learning curve, is suitable for most patients and keeps the surgeon within their comfort zone. Early experience has been good with notable early return of mobility, and well received by cardiologists. Experience with initial 55 cases will be presented. http://dx.doi.org/10.1016/j.hlc.2017.03.150
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Learning Coronary Anastomosis Quantifying the Process James Wood, Dr ∗ , Fraser Callaghan, Dr, Michael Wilson, Prof, Stuart Grieve, Prof Macquarie University, Sydney, NSW, Australia Purpose: To use computational fluid dynamics (CFD) to quantify flow through coronary anastomoses carried out by trainee surgeons. Methodology: All 24 (2015) RACS Cardiothoracic SET trainees carried out two simulated coronary anastomoses. 2 mm diameter silicone vessels were anastomosed end to side using 7-0 prolene. Each anastomosis was CT scanned. A centre-line was constructed for each of the native and graft vessels using a semi-automatic technique. A fully automatic algorithm then segmented the lumen space, generated a CFD mesh and performed CFD simulations assuming flow rates of 30 and 5 mL/min in the graft and native vessels respectively. Results: Velocity, pressure drop and radius were calculated for each anastomosis. Despite externally similar appearances of the completed anastomoses, lumen constriction, and consequently haemodynamics, varied widely in the group according to SET trainee level: mean (±SD) minimum lumen radius, peak velocity and pressure drop respectively for SET Level: SET2 0.47 ± 0.04 mm, 83.8 ± 17 cm/s, 1.001 ± 0.36 mmHg; SET4: 0.51 ± 0.10 mm, 75.1 ± 33 cm/s, 0.89 ± 0.44 mmHg; SET6: 0.44 ± 0.03 mm, 80 ± 21 cm/s, 0.95 ± 0.36 mmHg. Conclusion: Using CFD we have been able to characterise haemodynamic performance of coronary anastomoses carried out in a training simulation. We believe this will be an important tool to direct training and optimising patient outcomes. http://dx.doi.org/10.1016/j.hlc.2017.03.151 Relationship Between Urinary Oxygen Tension During Cardiopulmonary Bypass and Development of Acute Kidney Injury Michael Zhu, Mr ∗ , Andrew Cochrane, A/Prof/, Julian Smith, Prof/, Gerard Harrop, Mr, Roger Evans, A/Prof/ Department of Surgery, Monash University and Department of Cardiothoracic Surgery, Monash Health, Melbourne, VIC, Australia Purpose: Renal medullary hypoxia may be a common pathway in the development of acute kidney injury (AKI). There are no validated methods to detect medullary hypoxia in patients. However, experimental findings indicate that changes in urinary oxygen tension (UPO2) reflect changes in medullary PO2. Therefore, we evaluated the relationship between intraoperative UPO2 and the development of AKI after cardiopulmonary bypass (CPB). Methods: From January 2015 to July 2016, thirty-five adult patients undergoing on-pump cardiac surgery were prospectively enrolled. UPO2 was continuously recorded