Does epiaortic ultrasound screening reduce perioperative stroke in patients undergoing coronary surgery? A topical review

Although the occurrence of stroke in patients undergoing coronary artery bypass grafting (CABG) is decreasing, it remains an important concern. Therefore, it is important to identify and adopt strategies that can decrease the incidence of stroke in these patients. One of the strategies that have demonstrated the potential to decrease the rate of post-CABG stroke is an assessment of aorta for atherosclerosis before surgery and changing the surgical plan accordingly to minimize the stroke risk. This assessment can be done through palpation of the aorta, transesophageal echocardiography (TEE), and epiaortic ultrasound scanning (EAS). EAS has shown superiority over both palpation and TEE for intraoperative evaluation of aorta. However, despite the evidence demonstrating reduced stroke rates with the EAS-guided approach, EAS is not yet the standard of care procedure in patients undergoing CABG. Therefore, we have reviewed the literature for evidence that supports the routine use of EAS in patients undergoing coronary surgery and have presented solutions to overcome the barriers to its routine use.

Oral anticoagulation, stroke and thromboembolism in patients with atrial fibrillation and valve bioprosthesis

Vitamin K antagonists are currently recommended in patients with ‘valvular’ atrial fibrillation (AF), e. g. those having mitral stenosis or artificial heart valves. We compared thromboembolic risk in patients with ‘non valvular’ AF and in those with AF and biological valve replacement (valve bioprosthesis). Among 8962 AF patients seen between 2000 and 2010, a diagnosis of ‘non-valvular AF’ was found in 8053 (94 %). Among patients with ‘valvular’ AF, 549 (6 %) had a biological prosthesis. The patients with bioprosthesis were older and had a higher CHA2DS2-VASc score than those with non valvular AF. After a follow-up of 876 é 1048 days (median 400 days, interquartile range 12–1483), the occurrence of thromboembolic events was similar in AF patients with bioprosthesis compared to those with ‘non valvular’ AF (hazard ratio [HR] 1.10 95 % confidence interval [CI] 0.83–1.45, p=0.52, adjusted HR 0.93, 95 %CI 0.68–1.25, p=0.61). Factors independently associated with increased risk of stroke/TE events were older age (HR 1.25, 95 %CI 1.16–1.34 per 10-year increase, p> 0.0001) and higher CHA2DS2-VASc score (HR 1.35, 95 %CI 1.24–1.46, p> 0.0001) whilst female gender (HR 0.75, 95 %CI 0.62–0.90, p=0.002), use of vitamin K antagonist (HR 0.83, 95 %CI 0.71–0.98, p=0.03) were independently associated with a lower risk of stroke/TE. Neither the presence of bioprosthesis nor the location of bioprosthesis was independent predictor for TE events. In conclusion, AF patients with bioprosthesis had a non-significantly higher risk of stroke/TE events compared to patients with non-valvular AF. Second, the CHA2DS2-VASc score was independently associated with an increased risk of TE events, and was a valuable determinant of TE risk both in AF patients with non-valvular AF as well as those with bioprosthesis, whether treated or not treated with OAC.

Note: The review process for this paper was fully handled by Christian Weber, Editor in Chief.

How to define valvular atrial fibrillation?

Atrial fibrillation (AF) confers a substantial risk of stroke. Recent trials comparing vitamin K antagonists (VKAs) with non-vitamin K antagonist oral anticoagulants (NOACs) in AF were performed among patients with so-called "non-valvular" AF. The distinction between "valvular" and "non-valvular" AF remains a matter of debate. Currently, "valvular AF" refers to patients with mitral stenosis or artificial heart valves (and valve repair in North American guidelines only), and should be treated with VKAs. Valvular heart diseases, such as mitral regurgitation, aortic stenosis (AS) and aortic insufficiency, do not result in conditions of low flow in the left atrium, and do not apparently increase the risk of thromboembolism brought by AF. Post-hoc analyses suggest that these conditions probably do not make the thromboembolic risk less responsive to NOACs compared with most forms of "non-valvular" AF. The pathogenesis of thrombosis is probably different for blood coming into contact with a mechanical prosthetic valve compared with what occurs in most other forms of AF. This may explain the results of the only trial performed with a NOAC in patients with a mechanical prosthetic valve (only a few of whom had AF), where warfarin was more effective and safer than dabigatran. By contrast, AF in the presence of a bioprosthetic heart valve or after valve repair appears to have a risk of thromboembolism that is not markedly different from other forms of "non-valvular" AF. Obviously, we should no longer consider the classification of AF as "valvular" (or not) for the purpose of defining the aetiology of the arrhythmia, but for the determination of a different risk of thromboembolic events and the need for a specific antithrombotic strategy. As long as there is no better new term or widely accepted definition, "valvular AF" refers to patients with mitral stenosis or artificial heart valves. Patients with "non-valvular AF" may have other types of valvular heart disease. One should emphasize that "non-valvular AF" does not exclude patients with some types of valvular heart disease from therapy with NOACs.

Coronary artery bypass grafting: Part 2--optimizing outcomes and future prospects

Since first introduced in the mid-1960s, coronary artery bypass grafting (CABG) has become the standard of care for patients with coronary artery disease. Surprisingly, the fundamental surgical technique itself did not change much over time. Nevertheless, outcomes after CABG have dramatically improved over the first 50 years. Randomized trials comparing percutaneous coronary intervention (PCI) to CABG have shown converging outcomes for select patient populations, providing more evidence for wider use of PCI. It is increasingly important to focus on the optimization of the short- and long-term outcomes of CABG and to reduce the level of invasiveness of this procedure. This review provides an overview on how new techniques and widespread consideration of evolving strategies have the potential to optimize outcomes after CABG. Such developments include off-pump CABG, clampless/anaortic CABG, minimally invasive CABG with or without extending to hybrid procedures, arterial revascularization, endoscopic vein harvesting, intraprocedural epiaortic scanning, graft flow assessment, and improved secondary prevention measures. In addition, this review represents a framework for future studies by summarizing the areas that need more rigorous clinical (randomized) evaluation.

Overcoming Challenges in the Management of Critical Events During Cardiopulmonary Bypass

Critical events during cardiopulmonary bypass (CPB) can challenge the most experienced perfusionists, anesthesiologists, and surgeons and can potentially lead to devastating outcomes. Much of the challenge of troubleshooting these events requires a key understanding of these situations and a well-defined strategy for early recognition and treatment. Adverse situations may be anticipated prior to going on CPB. Atherosclerosis is pervasive, and a high plaque burden may have implications in surgical technique modification and planning of CPB. Hematologic abnormalities such as cold agglutinins, antithrombin III deficiency, and hemoglobin S have been discussed with emphasis on managing complications arising from their altered pathophysiology. Jehovah’s witness patients require appropriate techniques for cell salvage to minimize blood loss. During initiation of CPB, devastating situations leading to acute hypoperfusion and multiorgan failure may be encountered in patients undergoing surgery for aortic dissection. Massive air emboli during CPB, though rare, necessitate an urgent diagnosis to detect the source and prompt management to contain catastrophic outcomes. Gaseous microemboli remain ubiquitous and continue to be a major concern for neurocognitive impairment despite our best efforts to improve techniques and refine the CPB circuit. During maintenance of CPB, adverse events reflect inability to provide optimal perfusion and can be ascribed to CPB machine malfunction or physiological aberrations. We also discuss critical events that can occur during perfusion and the need to monitor for organ perfusion in altered physiologic states emanating from hemodilution, hypothermia, and acid–base alterations.

Epiaortic ultrasound assessment of the aorta in cardiac surgery

The dislodgement of atheroma from the ascending aorta and proximal arch is a major cause of stroke and neurological injury following cardiac surgery. The accurate detection of atheroma prior to aortic manipulation is necessary to facilitate surgical strategies to reduce the risk of embolisation. The traditional method for atheroma detection is manual palpation by the surgeon. This technique misses about half the number of the atheroma lesions, as the soft (non-calcified) lesions offer little resistance to the surgeon's fingers. Trans-oesophageal echocardiography (TOE) is commonly used in cardiac surgery, but the interposition of the bronchus between the aorta and the oesophagus causes an ultrasound 'blind spot' in the ascending aorta and proximal arch, such that it does not offer improved detection compared to manual palpation. Accurate detection of atheroma requires direct ultrasound assessment using epiaortic scanning, with a high-frequency, linear-array probe. This allows the surgeon to correctly assess and localise any atheroma. In this article, a suggested epiaortic examination sequence is described and strategies for surgeons to avoid atheroma are discussed.