Research

Seco M, Edelman JJ, Yan TD, Wilson MK, Bannon PG, Vallely MP

Ann Cardiothorac Surg 2013 Jul;2(4):408-18

PMID: 23977616

Abstract

BACKGROUND: Advancements in surgical robotic technology over the last two decades have enabled coronary artery bypass grafting to be performed totally endoscopically, and have the potential to significantly change clinical practice in the future.

METHODS: A systematic review of studies reporting clinical outcomes of total endoscopic coronary artery bypass grafting (TECABG) was performed.

RESULTS: 14 appraised studies included 880 beating heart TECABGs, 360 arrested heart TECABGs, 633 one-vessel operations and 357 two-vessel operations. Patients were generally low-risk. There was a significant learning curve. The weighted means for short-term beating heart and arrested heart TECABG results respectively were: intraoperative exclusion rate of 5.7% and 1.9%, intraoperative conversion rate of 5.6% and 15.0%, all-cause mortality of 1.2% and 0.4%, stroke of 0.7% and 0.8%, myocardial infarction of 0.8% and 1.8%, new onset atrial fibrillation of 10.7% and 5.1% and post-operative reintervention rate of 2.6% and 2.3%. The overall rate of short term postoperative graft patency for beating heart and arrested heart TECABG was 98.3% and 96.4% respectively.

CONCLUSIONS: Appropriate patient selection was important in minimizing the risk of intraoperative and postoperative complications. Short-term outcomes of both beating and arrested heart TECABG were acceptable, but results so far have been heterogeneous. There were fewer studies reporting intermediate to long-term outcomes, but results were encouraging, and further investigation and development of the procedure is warranted.

Byrom MJ, Ng MK, Bannon PG

Ann Cardiothorac Surg 2013 Jul;2(4):435-43

PMID: 23977620

Abstract

No currently available conduit meets the criteria for an ideal coronary artery bypass graft. The perfect conduit would combine the availability and complication-free harvest of a synthetic vessel with the long-term patency performance of the internal mammary artery. However, current polymer conduits suffer from inelastic mechanical properties and especially poor surface biocompatibility, resulting in early loss of patency as a coronary graft. Approaches to manufacture an improved conduit using new polymers or polymer surfaces, acellular matrices, or cellular constructs have to date failed to achieve a commercially successful alternative. Elastin, by mimicking the native extracellular environment as well as providing elasticity, provides the ‘missing link’ in vascular conduit design and brings new hope for realization of the perfect conduit.

Vallely MP, Edelman JJ, Wilson MK

Ann Cardiothorac Surg 2013 Jul;2(4):570-7

PMID: 23977638

Abstract

Bilateral internal mammary artery (BIMA) grafts are used for coronary revascularisation by only a minority of surgeons, despite a growing body of evidence suggesting improved survival when compared to use of only one internal mammary artery with additional saphenous vein grafts. Herein we review the evidence supporting revascularisation with BIMA and suggest reasons why the majority of surgeons use only one internal mammary artery. We discuss technical considerations, various graft combinations and the use of BIMA to facilitate anaortic off-pump coronary artery bypass (OPCAB).

Tian DH, Wan B, Bannon PG, Misfeld M, Lemaire SA, Kazui T, Kouchoukos NT, Elefteriades JA, Bavaria JE, Coselli JS, Griepp RB, Mohr FW, Oo A, Svensson LG, Hughes GC, Underwood MJ, Chen EP, Sundt TM, Yan TD

Ann Cardiothorac Surg 2013 May;2(3):261-70

PMID: 23977593

Abstract

INTRODUCTION: Recognizing the importance of neuroprotection in aortic arch surgery, deep hypothermic circulatory arrest (DHCA) now underpins operative practice as it minimizes cerebral metabolic activity. When prolonged periods of circulatory arrest are required, selective antegrade cerebral perfusion (SACP) is supplemented as an adjunct. However, concerns exist over the risks of SACP in introducing embolism and hypo- and hyper-perfusing the brain. The present meta-analysis aims to compare postoperative outcomes in arch surgery using DHCA alone or DHCA + SACP as neuroprotection strategies.

METHODS: Electronic searches were performed using six databases from their inception to January 2013. Two reviewers independently identified all relevant studies comparing DHCA alone with DHCA + SACP. Data were extracted and meta-analyzed according to pre-defined clinical endpoints.

RESULTS: Nine comparative studies were identified in the present meta-analysis, with 648 patients employing DHCA alone and 370 utilizing DHCA + SACP. No significant differences in temporary or permanent neurological outcomes were identified. DHCA + SACP was associated with significantly better survival outcomes (P=0.008, I(2)=0%), despite longer cardiopulmonary bypass time. Infrequent and inconsistent reporting of other clinical results precluded analysis of systemic outcomes.

CONCLUSIONS: The present meta-analysis indicate the superiority of DHCA + SACP in terms of mortality outcomes.

Yan TD, Bannon PG, Bavaria J, Coselli JS, Elefteriades JA, Griepp RB, Hughes GC, Lemaire SA, Kazui T, Kouchoukos NT, Misfeld M, Mohr FW, Oo A, Svensson LG, Tian DH

Ann Cardiothorac Surg 2013 Mar;2(2):163-8

PMID: 23977577

Abstract

Considered a standard part of aortic arch surgery, hypothermia can sufficiently reduce cerebral metabolic demand to permit reasonable periods of circulatory arrest. Yet despite its ubiquitous application and critical importance, temperature classification in hypothermic circulatory arrest is still without clear definition. The following Consensus from experts in high-volume aortic institutions defines ‘profound’, ‘deep’, ‘moderate’, and ‘mild’ hypothermia and recommends standardized monitoring sites, so as to facilitate more consistent reporting and robust analysis.

Tian DH, Wan B, Bannon PG, Misfeld M, Lemaire SA, Kazui T, Kouchoukos NT, Elefteriades JA, Bavaria J, Coselli JS, Griepp RB, Mohr FW, Oo A, Svensson LG, Hughes GC, Yan TD

Ann Cardiothorac Surg 2013 Mar;2(2):148-58

PMID: 23977575

Abstract

INTRODUCTION: A recent concern of deep hypothermic circulatory arrest (DHCA) in aortic arch surgery has been its potential association with increased risk of coagulopathy, elevated inflammatory response and end-organ dysfunction. Recently, moderate hypothermic circulatory arrest (MHCA) with selective antegrade circulatory arrest (SACP) seeks to negate potential hypothermia-related morbidities, while maintaining adequate neuroprotection. The present meta-analysis aims to compare postoperative outcomes in arch surgery using DHCA or MHCA+SACP as neuroprotective strategies.

METHODS: Electronic searches were performed using six databases from their inception to January 2013. Two reviewers independently identified all relevant studies comparing DHCA with MHCA+SACP, as defined by a recent hypothermia temperature consensus. Data were extracted and meta-analyzed according to pre-defined clinical endpoints.

RESULTS: Nine comparative studies were identified for inclusion in the present meta-analysis. Stroke rates were significantly lower in patients undergoing MHCA+SACP (P=0.0007, I(2)=0%), while comparable results were observed with temporary neurological deficit, mortality, renal failure or bleeding. Infrequent and inconsistent reporting of systemic outcomes precluded analysis of other systemic outcomes.

CONCLUSIONS: The present meta-analysis indicated the superiority of MHCA+SACP in terms of stroke risk.

Cao C, Ang SC, Indraratna P, Manganas C, Bannon P, Black D, Tian D, Yan TD

Ann Cardiothorac Surg 2013 Jan;2(1):10-23

PMID: 23977554

Abstract

BACKGROUND: Transcatheter aortic valve implantation (TAVI) has emerged as an acceptable treatment modality for patients with severe aortic stenosis who are deemed inoperable by conventional surgical aortic valve replacement (AVR). However, the role of TAVI in patients who are potential surgical candidates remains controversial.

METHODS: A systematic review was conducted using five electronic databases, identifying all relevant studies with comparative data on TAVI versus AVR. The primary endpoint was all-cause mortality. A number of periprocedural outcomes were also assessed according to the Valve Academic Research Consortium endpoint definitions.

RESULTS: Fourteen studies were quantitatively assessed and included for meta-analysis, including two randomized controlled trials and eleven observational studies. Results indicated no significant differences between TAVI and AVR in terms of all-cause and cardiovascular related mortality, stroke, myocardial infarction or acute renal failure. A subgroup analysis of randomized controlled trials identified a higher combined incidence of stroke or transient ischemic attacks in the TAVI group compared to the AVR group. TAVI was also found to be associated with a significantly higher incidence of vascular complications, permanent pacemaker requirement and moderate or severe aortic regurgitation. However, patients who underwent AVR were more likely to experience major bleeding. Both treatment modalities appeared to effectively reduce the transvalvular mean pressure gradient.

CONCLUSIONS: The available data on TAVI versus AVR for patients at a higher surgical risk showed that major adverse outcomes such as mortality and stroke appeared to be similar between the two treatment modalities. Evidence on the outcomes of TAVI compared with AVR in the current literature is limited by inconsistent patient selection criteria, heterogeneous definitions of clinical endpoints and relatively short follow-up periods. The indications for TAVI should therefore be limited to inoperable surgical candidates until long-term data become available.

Harris RS, Yan TD, Black D, Bannon PG, Bayfield MS, Hendel PN, Wilson MK, Vallely MP

Heart Lung Circ 2013 Aug;22(8):618-26

PMID: 23422500

Abstract

BACKGROUND: In the era of TAVI, there has been renewed interest in the outcomes of conventional AVR for high-risk patients. This study evaluates the short- and long-term outcomes of AVR in octogenarians.

METHODS: A retrospective review was performed of all 117 patients aged ≥ 80 years who underwent AVR, (isolated AVR (n = 60) or AVR+CABG (n = 57),) from August 2005 to February 2011 at Royal Prince Alfred Hospital and Strathfield Hospital. Univariate analysis was used to compare pre- and post-operative variables between younger and older subgroups (age 80-84, n = 82; age 85-89, n = 35 respectively). Long-term survival data was obtained from the National Death Index at the Australian Institute of Health and Welfare and survival curves were constructed using the Kaplan-Meier method.

RESULTS: The median age was 83 years (interquartile range, 81-85 years), 46.2% were females, the median EuroSCORE was 10.89% (interquartile range, 8.20-16.45%) and 16.2% of patients had a EuroSCORE ≥ 20%. The difference between subgroups for history of stroke was significant (p = .042). Post-operative complications included pleural effusion (12.8%), new renal failure (4.3%) and respiratory failure (4.3%). The rate of major adverse events was extremely low, with no cases of stroke. The 30-day mortality rate was 3.4%. There was a significant difference between subgroups for 30-day mortality (p = .007). 38.9% of patients were discharged home, 11.5% were transferred to another hospital and 38.9% spent a period of time in a rehabilitation institution post discharge. In terms of long-term survival, the six-month, one-year and three-year survival was 95.6%, 87.6% and 58.4% respectively.

CONCLUSIONS: Surgical AVR yields excellent short- and long-term outcomes for potentially high-risk, elderly patients.

Yu Y, Vallely M, Ng MK

J Invasive Cardiol 2013 Aug;25(8):409-10

PMID: 23913607

Abstract

An 83-year-old woman with multiple comorbidities and severe aortic stenosis presented with recurrent pulmonary edema. In light of her high surgical risk, a percutaneous strategy for her aortic stenosis was decided. Transcatheter aortic valve replacement using a balloon-expandable Edwards Sapien XT valve was performed under rapid ventricular pacing. Soon after valve deployment, the patient went into hemodynamic collapse due to annular root rupture with pericardial tamponade, necessitating urgent pericardial decompression. Using a valve-in-valve technique, with the deployment of a second Edward Sapien XT valve inside the first valve, the annular root rupture was successfully sealed leading to hemodynamic recovery.

Cao C, Manganas C, Horton M, Bannon P, Munkholm-Larsen S, Ang SC, Yan TD

J. Thorac. Cardiovasc. Surg. 2013 Aug;146(2):255-61

PMID: 22871565

Abstract

INTRODUCTION: The efficacy of coronary artery bypass graft (CABG) surgery for patients with ischemic heart disease is dependent on the patency of the selected conduit. The left internal thoracic artery is considered to be the best conduit for CABG. However, the preferred conduit between the radial artery (RA) and saphenous vein (SV) remains controversial. The present meta-analysis aims to establish the current level IA evidence on patency outcomes comparing the RA and SV.

METHODS: Electronic searches were performed using 6 databases from their inception to March 2012. Two reviewers independently identified all relevant randomized controlled trials (RCTs) comparing patency outcomes of RA and SV grafts after CABG. Data were extracted and meta-analyzed according to angiographic end points at specified follow-up intervals.

RESULTS: Five relevant RCTs were identified for inclusion in the present meta-analysis. Angiographic results indicated that the RA was significantly more likely to be completely patent and less likely to be associated with graft failure or complete occlusion at 4 years’ follow-up and beyond. However, the RA was significantly more likely to be associated with string sign at 1 year of follow-up.

CONCLUSIONS: While acknowledging the limitations of heterogeneous surgical techniques, results from the present meta-analysis suggest potential superiority of the RA compared with the SV at midterm angiographic follow-up. However, the increased incidence of string sign associated with the RA is of potential clinical concern. Further research should be directed at correlating angiographic findings of string sign and graft failure to clinical symptoms and major adverse cardiac and cerebrovascular events at long-term follow-up.