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© 2004 European Association of Cardio-Thoracic Surgery
Can epiaortic ultrasound reduce the incidence of intraoperative stroke during cardiac surgery?Department of Cardiothoracic Surgery, Wythenshawe Hospital, South Moor Road, Manchester M23 9LT, UK
* Corresponding author. Department of Cardiothoracic Surgery, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WL, UK. Tel.: +44-7801548122 Received September 15, 2003; accepted September 19, 2003
A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether changing operative technique based on epiaortic ultrasound reduces the incidence of intra-operative stroke during cardiac surgery? Altogether 179 papers were found using the reported search, of which eight presented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results, and study weaknesses of these papers are tabulated. We conclude that epiaortic ultrasound is superior to manual palpation in detecting atherosclerosis in the ascending aorta, and the severity of atherosclerosis found is closely correlated to the incidence of postoperative stroke. No touch techniques in patients with severe atherosclerosis may avert this increase in the incidence of stroke.
Key Words: Evidence-based medicine; Thoracic surgery; Ultrasonography; Aorta; Thoracic
You are about to perform an on-pump quadruple coronary arterial bypass graft on a 75-year-old lady with a poor ejection fraction. In addition, she has had a carotid endarterectomy 5 years ago and is known to have some peripheral vascular disease, and thus you are anxious that she may have an atherosclerotic ascending aorta, which could cause an intra-operative stroke. You would like to use your usual surgical technique of cross-clamping but you wonder whether using intra-operative ultrasound to decide on your operative approach would reduce the chance of stroke for your patient. 1.1. Three-part question In [patients undergoing cardiac surgery] does [epiaortic ultrasound] reduce the incidence of [intra-operative stroke]?
1.2. Search strategy
1.3. Search outcome
1.4. Comment(s) There are several areas of evidence that need to be considered prior to using epiaortic ultrasound (EAU) as part of routine surgery. First, it is well established that EAU detects a far higher level of atherosclerosis in the ascending aorta compared to manual palpation. Van der Linden [4] reported that only 39.6% of significant atheroma detected on EAU was detected by manual palpation. Duda [8] reported that when EAU was not used 1.8% of patients were thought to have significant atherosclerosis of the aorta on manual palpation, but when EAU was used 14% of patients were found to have significant atherosclerosis. The incidence of moderate atherosclerosis found by EAU ranged from 10 to 48% and severe atherosclerosis ranged from 3.5 to 16% in these studies. Second, it is well established that patients with moderate or severe atherosclerosis of the aorta have a significantly higher incidence of stroke. Van der Linden [4] found that presence of atheroma increased the stroke rate from 1.8 to 8.7%. Ura [6] found that severe atheroma increased the incidence of stroke from under 3 to 21%. Goto [1] found that neurobehavioral outcome was significantly worse in the presence of severe atherosclerosis, with 28% of these patients having a decrease in neurophysiological tests compared to only 8% in groups with normal or moderate scores. Many other papers not documented here also support these findings. Finally the more controversial issue is whether modifying the management of the ascending aorta based on epiaortic ultrasound can effectively reduce the incidence of stroke in patients attending for cardiac surgery. Goto [1] was unable to reduce the incidence of stroke by a range of modifications in technique although they report that in the 10 patients with severe atherosclerosis where a no-touch technique was used, no strokes occurred. Shimokawa [2] operated on 19% of their cohort of patients using a no touch technique for high risk patients, although one of these 54 patients had a stroke. Hangler [3] performed off pump CABG with a no touch technique in their patients with severe atherosclerosis and had a low stroke rate of only 2.8% in these patients, but Van der Linden [4] who used more minor modifications in technique including relocating the aortic cannulation site or site of proximal anastomosis had a stroke rate of 8.7%. Royse [5] used total arterial revascularisation with Y grafting for high risk patients and found a drop from 38 to 4% in abnormal neurobehavioral testing post-operatively. Ura [6] used more minor modifications and still used at least a single cross clamp and could not improve the stroke rate, but Hammon [7] reported that when epiaortic ultrasound was introduced into their clinical practise, there was a significant improvement in neurobehavioral testing at 1 month post operation. Finally, Duda [8] reported that the introduction of EAU into their clinical practise eliminated stroke in their patients when used in 195 patients. Introducing EAU into their practise, Duda's results showed that a modification to their usual technique was required for every 14 ultrasound scans performed. Results are mixed as to whether the stroke rate can be reduced as a result of EAU examination. Five of the eight studies showed a reduction in the stroke rate as a result of modification to surgical technique after EAU. It may be that the degree of modification to the surgeon's operative technique when atherosclerosis is detected is the determining factor in these papers as to whether a reduction in stroke rate can be achieved, with a no touch technique being of most benefit in the highest risk patients.
1.5. Clinical bottom line
ICVTS on-line discussion Author: Dr. Joel Dunning, Royal College of Surgeons Research Fellow, Dept Cardiothoracic Surgery, Manchester Royal Infirmar, Oxford Road, Manchester M13 3BW, UK Date: 31-Oct-2003 Message: Although not included in our topic, another paper is also probably worth mentioning here. Waring et al in the Annals of Thoracic Surgery in 1993 reported a large cohort of 1,200 patients undergoing CABG who all underwent Epiaortic Ultrasound as well as Carotid Duplex scanning. They reported that in patients with no aortic atherosclerosis the stroke rate was 1.1%. They also reported that while the stroke rate was 6.3% for patients with moderate or severe atherosclerotic disease who only had minor modifications to their operation, in 27 patients who had an ascending aortic replacement due to their severe atherosclerotic aortic disease there were no strokes. This study again provides support for the concept that minor modifications may be much less effective than 'no-touch techniques' or major modifications in attempting to reduce the stroke rates in these high risk patients. Reference [1]Waring TH, Davila-Roman VG, Daily BB, Murphy SF, Schechtman KB, BArzilai B, Kouchoukos NT. Strategy for the reduction of stroke Incidence in Cardiac Surgical Patients. Ann Thorac Surg 1993;55:1400–8 doi:10.1016/S1569-9293(03)00220-2
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Abstract
1. Clinical scenario
