Epiaortic Ultrasound for Assessment of Intraluminal Atheroma; Insights from the REGROUP Trial

The Rationalisation of Intra-Operative Imaging During Cardiac Surgery: A Systematic Review

INTRODUCTION

One critical complication of cardiac surgery is cerebrovascular accidents (CVAs). Ascending aorta atherosclerosis poses a significant risk of embolisation to distal vessels and to cerebral arteries. Epi-aortic ultrasonography (EUS) is thought to offer a safe, high-quality accurate visualisation of the diseased aorta to guide the surgeon on the best surgical approach to the planned procedure and potentially improve neurological outcomes post-cardiac surgery.

METHOD

The authors conducted a comprehensive search of PubMed, Scopus and Embase. Studies that reported on epi-aortic ultrasound use in cardiac surgery were included. Major exclusion criteria were: (1) abstracts, conference presentations, editorials, literature reviews; (2) case series with <5 participants; (3) epi-aortic ultrasound in trauma or other surgeries.

RESULTS

A total of 59 studies and 48,255 patients were included in this review. Out of the studies that reported patient co-morbidities prior to cardiac surgery, 31.6% had diabetes, 59.5% had hyperlipidaemia and 66.1% had a diagnosis of hypertension. Of those that reported significant ascending aorta atherosclerosis found on EUS, this ranged from 8.3% of patients to 95.2% with a mean percentage of 37.8%. Hospital mortality ranged from 7% to 13%; four studies reported zero deaths. Long-term mortality and stroke rate varied significantly with hospital duration.

CONCLUSION

Current data have shown EUS to have superiority over manual palpation and transoesophageal echocardiography in the prevention of CVAs following cardiac surgery. Yet, EUS has not been implemented as a routine standard of care. Extensive adoption of EUS in clinical practice is warranted to aid large, randomised trials before making prospective conclusions on the efficacy of this screening method.

Clinical trials proposed for the VA Cooperative Studies Program: Success rates and factors impacting approval

The process by which funding organizations select among the myriad number of proposals they receive is a matter of significant concern for researchers and the public alike. Despite an extensive literature on the topic of peer review and publications on criteria by which clinical investigations are reviewed, publications analyzing peer review and other processes leading to government funding decisions on large multi-site clinical trials proposals are sparse. To partially address this gap, we reviewed the outcomes of scientific and programmatic evaluation for all letters of intent (LOIs) received by the Department of Veterans Affairs (VA) Cooperative Studies Program (CSP) between July 4, 2008, and November 28, 2016. If accepted, these LOIs represented initial steps towards later full proposals that also underwent scientific peer review. Twenty-two of 87 LOIs were ultimately funded and executed as CSP projects, for an overall success rate of 25%. Most proposals which received a negative decision did so prior to submission of a full proposal. Common reasons for negative scientific review of LOIs included investigator inexperience, perceived lack of major scientific impact, lack of preliminary data and flawed or confused experimental design, while the most common reasons for negative reviews of final proposals included questions of scientific impact and issues of study design, including outcome measures, randomization, and stratification. Completed projects have been published in high impact clinical journals. Findings highlight several factors leading to successfully obtaining funding support for clinical trials. While our analysis is restricted to trials proposed for CSP, the similarities in review processes with those employed by the National Institutes of Health and the Patient Centered Outcomes Research Institute suggest the possibility that they may also be important in a broader context.

Surgical strategies for severely atherosclerotic (porcelain) aorta during coronary artery bypass grafting

Porcelain aorta (PA) is an asymptomatic atherosclerotic disease, characterized by circumferential calcification throughout the whole perimeter of the aorta. It is seen in 2% to 9.3% of patients undergoing elective coronary artery bypass grafting (CABG) and makes manipulation of the ascending aorta impossible. It has been clearly shown that most emboli seen and detected during the CABG procedure occur during aortic cross-clamping and aortic side-clamping. Manipulation of porcelain or a severely atherosclerotic aorta increases the risk of perioperative stroke. The incidence of stroke after CABG is between 0.48% and 2.9%, and the risk is correlated with the extent and severity of the atherosclerotic disease. A conventional CABG procedure involves successive steps that include cannulation of the ascending aorta, application of a cross-clamp to the aorta, and partial clamping of the aorta to create the proximal anastomosis. Therefore in procedures that involve cannulation, clamping, or proximal anastomosis, and where aortic manipulation is inevitable, preassessment of the atherosclerotic aortic plaques is crucial. Although many surgeons still rely on intraoperative manual aortic palpation, this approach has very low sensitivity and underestimates the severity of the atherosclerotic illness. Imaging methods including preoperative computed tomography or intraoperative epiaortic ultrasonography enable modification of the surgical technique according to the severity of atherosclerosis. Various surgical techniques have been described to reduce the risk of atheroembolism that may lead to cerebrovascular events in patients with severely atherosclerotic ascending aorta. Anaortic or “no-touch” techniques that do not utilize aortic manipulation may significantly decrease the development of neurological complications by avoiding aortic maneuvers known to cause emboli. In cases where severe atherosclerotic disease or other factors preclude safe use of the ascending aorta, modifications in the surgical techniques, such as switching to different cannulation sites including the axillary/subclavian, femoral and innominate arteries, or using hypothermic ventricular fibrillation and in-situ pedicled arterial grafts, or performing proximal anastomoses at alternative anatomical locations will enable CABG operations to be performed safely with low morbidity and mortality rates in patients with porcelain aortas.