Myocardial ischaemia, infarction and cardiac-related death following carotid endarterectomy: risk assessment by thallium myocardial perfusion scan compared with clinical examination

Are there commonalities among audit tools used to measure carotid endarterectomy outcomes in New South Wales?

BACKGROUND

To prepare for a state-wide audit of carotid endarterectomy (CEA), we sought to ascertain pre-existing practices and identify common process and outcome measures among audits tools used by NSW vascular surgeons.

METHOD

Telephone survey comprising five questions about CEA audit practices.

RESULTS

Of 37 known vascular surgeons in NSW, all performed CEA and agreed to participate in our telephone survey (response rate 100%). All but one reported collecting CEA data (97%). Two thirds of these collected data prospectively. From those 19 surgeons (51%) who stated that they used standard tools for audit, we received five CEA-specific tools. Process measures common to all five were: side of CEA, date of operation, sex, past history of hypertension, history of diabetes, use of shunt, use of patch. There were only three outcome measures common to all five CEA-specific tools: postoperative transient ischaemic attack (TIA), postoperative stroke, and postoperative death. Data about outcomes beyond discharge were inconsistently collected.

CONCLUSIONS

While most vascular surgeons in NSW report collecting information about CEA outcomes, not all do so prospectively. Only three outcomes (postoperative TIA, postoperative stroke and death) were common to all tools, inviting the development and use of a comprehensive and standard tool.

Reconstructive surgery of the extracranial arteries

The first carotid endarterectomy (CEA) is usually accredited to Eastcott who reported in 1954 the successful incision of a diseased carotid bulb with end-to-end anastomosis of the internal carotid artery (ICA) to the common carotid artery (CCA). During the following years surgeons were quick to adopt and improve the intuitively attractive procedure. But by the early to mid 1980s several leading neurologists began to question the growing number of CEAs performed at that time. Six major CEA trials were then designed which are now completed or nearing completion. Most conclusive data are available from the North American Symptomatic Carotid Endarterectomy Trial (NASCET) for symptomatic carotid disease, and from the Asymptomatic Carotid Atherosclerosis Study (ACAS) for asymptomatic carotid disease. The key result of these studies is that CEA is beneficial to high grade symptomatic and asymptomatic carotid stenosis. While the benefit in symptomatic disease is clear, it may be negligible in asymptomatic patients suffering from other medical conditions, the most important being coronary artery disease. Since the conclusions from the different studies vary significantly, guidelines and recommendations with regard to CEA have been issued by a number of interest groups, so-called consensus conferences. The best known guidelines are published by the American Heart Association (AHA). However, the practice of interest groups to issue guidelines is currently being criticized, the main reason being that interest groups have different ideas and all claim the right to issue guidelines. At present we recommend CEA for symptomatic high-grade stenosis in patients without significant coincident disease. With regard to asymptomatic stenosis we suggest surgery to otherwise healthy patients if the stenosis is very narrow or progressive. Preoperative evaluation has changed over the years. Currently we recommend duplex sonography in combination with intra- and extracranial magnetic resonance angiography (MRA). Concurrent coronary artery disease is a major consideration in the perioperative management, and the use of a specific algorithm is recommended. Surgery is performed under general anaesthesia with intraoperative monitoring such as electroencephalography (EEG) and transcranial Doppler (TCD). A temporary intraluminal shunt is used selectively if after cross-clamping the flow velocity in the middle cerebral artery (MCA) falls to below 30 to 40% of baseline. For years we employed routine barbiturate neuroprotection during cross-clamping. At the present time we use barbiturate selectively, if the flow velocity in the MCA falls to below 30 to 40% of baseline and if the use of a temporary intraluminal shunt is not possible due to difficult anatomic conditions. The reason to abandon systematic barbiturate protection was to accelerate recovery from anaesthesia. Our patients are monitored overnight on the ICU or a surveillance unit. Routine hospitalization after surgery is 5 to 7 days with a control duplex sonography being performed prior to discharge. A number of details with regard to surgical technique and perioperative management are a matter of discussion. Our surgical routine is described here step by step. Such management resulted in 6 major complications among the 402 cases with 4 of cardiopulmonary and 2 of cerebrovascular origin. For the future we can expect the development of percutaneous transluminal techniques competing with standard carotid endarterectomy. At the present time several comparative studies are under way. Irrespective of the technical approach to treat carotid stenosis, several other issues have to be clarified before long. One of the major unresolved items is the timing of treatment after completed stroke. In this regard prospective trials need to be performed. Although numerically not as important as carotid stenosis, vertebral artery (VA) and subclavian artery (SA) stenoses are more and more accepted as indication for surgical

Extracranial arterial reconstruction for atheromatous stenotic disease

Risk factors for stroke and for carotid stenosis in the Japanese population are reviewed and the variations between rates of carotid endarterectomy in different populations discussed. The evolution of carotid plaques and the involvement of intraplaque hemorrhage in embolism and hemodynamic inadequacy in causing focal cerebral ischemic events are described. The indications for operation are presented together with an assessment of fitness for operation, with particular emphasis on the influence of heart disease on perioperative morbidity and late survival. Combined carotid and coronary reconstruction is carried out when severe disease of both systems is present (138 patients). The technique of carotid endarterectomy involves minimal dissection posterior to the common and internal carotid arteries to avoid vagal nerve injury. The pathology and symptoms of disease of the proximal great vessel together with techniques for revascularization are also presented.