Objectives: Coronary artery revascularization with cardiopulmonary bypass (ONCAB) has been reported to carry several risks for patients with poor left ventricular (LV) function (ejection fraction <30%). Off-pump CABG (OPCAB) has been proposed to result in a better outcome, but mid- and long-term survival rates have never been compared. The aim of this study is to assess the effect of cardiopulmonary bypass on this group of patients. Methods: In a 10-year period, a total of 934 patients with poor LV function undergoing isolated first-time coronary artery bypass graft were studied. They were divided into two groups, the ONCAB group, with 528 patients, and the OPCAB group with 406 patients. The EuroSCORE was significantly higher in the OPCAB group (P=0.049). After adjusting for the preoperative characteristics, postoperative complications, in-hospital mortality, mid-term survival rate (five years), and long-term survival rate (10 years) were compared. Results: The average number of grafts was 3.7 in the ONCAB group and 3.1 in the OPCAB group (P<0.001). Postoperative complications of ONCAB and OPCAB groups such as; atrial fibrillation (29.6% vs. 28.6%), renal failure (9.3% vs. 9.6%), stroke (2.3% vs. 0.7%), and perioperative myocardial infarction (MI) (3.8% vs. 2.0%), were comparable between groups. Length of intensive care unit stay, hospital stay and ventilation time were considerably shorter in the OPCAB group (P<0.05). The incidence of wound infection was also lower in the OPCAB patients (P<0.05). After adjusting for the preoperative characteristics the incidence of most postoperative complications remained the same between the two groups, except for MI, which was lower in the OPCABs (P<0.04). Despite a lower number of proximal anastomoses in the OPCAB patients, the rate of stroke remained the same between the OPCAB and ONCAB patients (0.09% vs. 1.6%). In-hospital mortality was higher in ONCAB compared to OPCAB (7.8% vs. 5.7%), but this difference did not reach statistical significance (P=0.21). Likewise, mid-term and long-term survival rates were similar even with matched preoperative characteristics. However, re-intervention rate was found to be higher in the OPCABs (P<0.001). Conclusions: Despite the reported benefits of OPCAB, there was no significant influence on the in-hospital mortality, mid-term survival or long-term survival in patients with LV dysfunction. With adequate myocardial protection in ONCAB and complete revascularization in OPCAB, similar results are achievable.
The optimum arterial perfusion pressure during cardiopulmonary bypass (CPB) remains uncertain. A correlation in some form with the patients' resting pressure almost certainly exists. Temperature and hematocrit affect blood viscosity. The optimum perfusion pressure during aortic surgery will vary after the initiation of CPB resulting cooling, heating, and hematocrit changes. Poiseuille's Law was used in conjunction with the previously published effects of temperature and hematocrit on blood viscosity to determine the perfusion pressure that would result in the same organ blood flow. Two different scenarios were modeled, constant flow and flow as predicted by Q10 to reflect required oxygen delivery. Temperature, hematocrit, and flow all have a large effect on blood viscosity and, thus, through Poiseuille's Law, blood pressure. As patients are cooled, their blood viscosity goes up through the inherent viscoelastic properties of blood. As temperature drops from 37 degrees to 17 degrees, viscosity doubles. This increased viscosity is offset by a reduction in hematocrit, which is invariably associated with CPB. As the hematocrit drops from 30% to 10%, viscosity of blood halves. These two factors clinically can cancel each other out. The figure demonstrates the effect on blood pressure of a constant flow for various temperature and hematocrits. Reduced need for oxygen delivery, secondary to the principles of Q10, can result in a lower than expected theoretical perfusion pressure. As temperature drops from 37 degrees to 17 degrees, based on Q10, oxygen delivery reduces by 75%. This indicates that flow can be reduced by over 60% if the hematocrit falls from 30% to 20%. This theoretical treatise predicts that blood pressure management should be temperature- and hematocrit-dependent. The target optimal blood pressure will vary during the course of surgery as a result of heating, cooling, and hemodilution. Clinical correlation is needed.
Objective The SAR-COV-2 pandemic has had an unprecedented effect on the UK's healthcare systems. To reduce spread of the virus, elective treatments and surgeries have been postponed or canceled. There has been a rise in the use of telemedicine (TM) as an alternative way to carry outpatient consultations. This systematic review aims to evaluate the extent to which TM may be able to support cardiac and vascular surgery patients in the COVID-19 era. Methods We looked into how TM can support the management of patients via triaging, preoperative, and postoperative care. Evaluations targeted the clinical effectiveness of common TM methods and the feasibility of applying those methods in the UK during this pandemic. Results Several studies have published their evidence on the benefit of TM and its benefit during COVID-19, the data related to cardiovascular surgery and how this will impact future practice of this speciality is emerging and yet larger studies with appropriate timing of outcomes to be published. Conclusion Overall, the use of virtual consultations and remote monitoring is feasible and best placed to support these patients via triaging and postoperative monitoring. However, TM can be limited by the need of sophisticated technological requirement and patients' educational and know-how computer literacy level.
Objective— Off-Pump Coronary Artery Bypass (OPCAB) surgery is gaining more popularity worldwide. The aim of this United Kingdom (UK) multi-center study was to assess the early clinical outcome of the OPCAB technique and perform a risk-stratified comparison with the conventional Coronary Artery Bypass Grafting (CABG) using the Cardio-Pulmonary Bypass (CPB) technique. Methods— Data were collected on 5,163 CPB patients from the database of the National Heart and Lung institute, Imperial College, University of London, and on 2,223 OPCAB patients from eight UK cardiac surgical centers, which run established OPCAB surgery programs. All patients had undergone primary isolated CABG for multi-vessel disease through a midline sternotomy approach, between January 1997 and April 2001. Postoperative morbidity and mortality were compared between the CPB and OPCAB patients after adjusting for case-mix. The mortality of the OPCAB patients was also compared, using risk stratification, to the mortality figures reported by the Society of Cardiothoracic Surgeons of Great Britain and Ireland (SCTS) based on 28,018 patients in the national database who were operated on between January 1996 and December 1999. Results— Morbidity and mortality were significantly lower in the OPCAB patients compared with the CPB patients and the UK national database of CABG patients, over the same period of time, after adjusting for case-mix. Conclusion— This study demonstrates that risk stratified morbidity and mortality are significantly lower in OPCAB patients than CPB patients and patients in the UK national database.
Under the unprecedented pressures of the global coronavirus disease 2019 (COVID-19) pandemic, there is an urgent requisite for successful strategies to safely deliver cardiac surgery. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first described in early December 2019, and the rapid spread and emergence of this virus has caused significant disruptions in the delivery of healthcare services worldwide.1,2 In particular, provision of cardiac surgery has been disproportionally affected due to reallocation of intensive care resources, such as ventilators.2Additionally, patients with pre-existing cardiovascular disease are likely to have comorbidities which are associated with poorer clinical outcomes in confirmed SARS-CoV-2 cases.3,4 Despite this, Yandrapalli and colleagues have reported the first case of a successful coronary artery bypass graft (CABG) operation in a patient with asymptomatic SARS-CoV-2 infection, which offers insights into how cardiac surgery could be adapted to solve the challenges of this pandemic.5In response to the burden of COVID-19 on healthcare systems in the United Kingdom (UK), elective cardiac surgeries have been delayed owing to the redistribution of intensive care resources and the unquantifiable risk of acquiring COVID-19.2 Likewise, cardiac surgery services have undergone structural remodelling into a centralised system in an attempt to continue provisions of emergency surgery alongside hospital management of COVID-19 patients.2Unsurprisingly, most cardiac surgery units across the globe have seen a sharp decline in surgeries as a result, and one unit reported an 83% reduction in cardiac index cases between 23rd March to 4th May 2020.2 Similar models have been used in Europe to manage healthcare services and increase intensive care capacity. For example in the Lombardy region of Italy, 16 out of 20 cardiac surgical units discontinued services and all urgent cases have been consequently diverted to the remaining four units for centralised services.6 Whilst these measures have been beneficial for supporting the focused management of COVID-19 patients, it is important to reflect upon the future consequences of delayed elective cardiac surgery. Indeed, such patients are likely to have progressive conditions and further work is needed to investigate the long-term impact of COVID-19 on mortality and morbidity in this cohort.The case report by Yandrapalli and colleagues highlight the importance of routine SARS-CoV-2 testing for all patients requiring cardiac surgery, especially for detecting asymptomatic or subclinical infections.5 Active SARS-CoV-2 infection may precipitate an overproduction of early response proinflammatory cytokines in post-operative period, leading to unfavourable surgical outcomes.7,8 Moreover, preliminary studies have shown that patients with established cardiovascular diseases may have a greater risk of increased SARS-CoV-2 infection severity and prognosis.9 Taken together, assessment for active infection is crucial for risk stratification. In addition, clinicians should consider the threshold for surgery when selecting patients for cardiac surgery. An international, multi-centre cohort study by COVIDSurg Collaborative which included 1128 confirmed SARS-CoV-2 patients undergoing a broad range of surgeries revealed that 30-day mortality risk was significantly associated with the patient demographics of male sex, an age of 70 years or older, and poor preoperative physical health status.10 Collectively, the risks and benefits of cardiac surgery should be carefully considered in such patients due to higher mortality risk.10Alternative therapeutic procedures with rapid discharge, such as percutaneous intervention or medical therapy, may be more appropriate to reduce SARS-CoV-2 related mortality and nosocomial infection risk.11Current evidence is limited for postoperative outcomes in cardiac surgery cases. In the aforementioned cohort study by COVIDSurg Collaborative, the 30-day mortality rate was 23.8%.10In addition, the study reported that 51.2% of patients had postoperative pulmonary complications, which was associated with a higher mortality rate of 38.0%.10 In another case report describing an emergency CABG operation, the asymptomatic patient succumbed to pulmonary complications arising from a SARS-CoV-2 infection confirmed postoperatively.12 The authors acknowledge that the undiagnosed infection may have triggered a refractory pathological response after cardiac surgery. Indeed, recent literature has suggested that patients with SARS-CoV-2 are at higher risk of developing thromboembolisms, possibly mediated by the interaction with angiotensin-converting enzyme 2 (ACE2) receptors.13Similarly, there is a consensus that SARS-CoV-2 has direct adverse effects on the myocardium due to high expression of ACE2.14 As such, SARS-CoV-2 can potentially trigger multisystem complications which require vigilant monitoring, especially in patients requiring cardiopulmonary bypass and at high risk of developing thromboembolisms. Cardiac surgery patients represent a vulnerable patient population, and this cohort may experience worse outcomes with SARS-CoV-2 infection based on the current available evidence. In the latest recommendation, UK currently advises all patients who are listed for elective cardiac surgery to self-isolate for 14 days prior to surgery date, in a measure to limit and contain the exposure of such cohort to the smallest possibilities of acquiring COVID-19.Currently, the future of cardiac surgery after the pandemic is unclear as the evidence is still emerging. However, the lessons learnt from these unprecedented times can be taken forward to inform future service planning. Moving forwards, routine screening of patients for SARS-CoV-2 infection will undoubtedly play a key role in identifying asymptomatic or subclinical infections. The preoperative UK National Health Service testing recommendations should be broadened so that all patients undergoing cardiac surgery are screened, given the higher risk of postoperative complications in this population. Similarly, repeat testing is important for monitoring patients for concomitant infections. Alongside changes to hospital protocol, service delivery will inevitably shift. The successful application of telemedicine during the pandemic has already been reported in the delivery of oncology services.15 Moreover, the benefits of telecardiology outside of the COVID-19 era have been previously reported, and cardiology services will likely embrace the utilisation of telemedicine for managing outpatient consultations.16 Units will also have to address the vast backlog of surgeries caused by cancellation of elective cardiac operations in a sustainable manner, with adequate hospital space and personal protective equipment availability.17 In order to resume success services, planning for this eventuality should begin now and patients at significant mortality risk due to delayed surgery need to be prioritised.Ultimately, clear guidelines should be implemented to ensure safe resumption of surgical services, whilst also reassuring patients concerned about safety.3 Whilst the future trajectory of this pandemic is uncertain, the insights from the impact of COVID-19 on cardiac surgery will undoubtedly shape the future delivery of cardiac surgery.
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