Aktuelle Aspekte der Anästhesie beim kardialen Risikopatienten

The Patient at Increased Cardiac Risk - Are there New Aspects?

In the last years numerous investigations focussed on anaesthesiological strategies for perioperative care of patients with or at risk for coronary artery disease (CAD). In these publications problems concerning preoperative risk stratification, prevention of intra- and postoperative myocardial ischaemia as well as anaesthesiological methods were discussed. However, some relevant issues are unsolved until now. Therefore, this mini symposium was aimed to present and discuss recent concepts of anaesthesia in patients at increased cardiac risk.

The prevalence of coronary artery disease (CAD) in the industrial nations has been calculated between 5 % and 7 %. Due to the rapid aging of the surgical population, the number of patients with an increased cardiac risk will increase continuously during the next decades. To date, approximately 8 millions non-cardiac operations were performed per year in Germany; about 1 million of these patients suffer from CAD. Perioperative myocardial infarctions occur in approximately 15.000 patients, mortality has been calculated between 20 - 50 %. Therefore, new concepts should be developed and introduced into the clinical setting in order to minimize the perioperative risk.

The purpose of preoperative evaluation and treatment is a first and relevant step to achieve this goal. In the University Hospital Hamburg-Eppendorf this is realized using a standardized evaluation list. Evaluation is performed by the surgeon on the peripheral ward, and if the result is pathological the patient is referred to cardiological consultation for further assessment and treatment. The advantage of this concept is to avoid unnecessary examinations and a reduction of costs.

Furthermore, the close cooperation with the cardiology consultant enables an early start of therapy with ß-blockers. Numerous studies demonstrated beneficial properties of these substances and recommend administration of ß-blockers for prevention of perioperative myocardial ischaemia in high-risk patients. Recent studies showed that the α₂-adrenoceptor agonist clonidine also reduces the rate of cardiac events, whereas calcium antagonists as well as nitrates were not effective.

The anaesthetic technique might also influence the incidence of cardiac morbidity and mortality. During the last years the number of studies concerning this issue increased, and it has been speculated that high-risk patients would benefit from administration of volatile anaesthetics. However, most of these investigations were performed in patients undergoing cardiac surgery, and the number of studies in patients at high cardiac risk undergoing non-cardiac surgery is unfortunately limited until now.

There is still a debate whether the type of anaesthesia - regional or general - has any substantial effect on the risk of perioperative myocardial ischaemia. The answer on this question is difficult due to methodological differences between clinical studies. However, a meta-analysis of 141 trials showed that the overall mortality was reduced by about one third in patients allocated to neuroaxial blockade. Thus, it was recommended on the one hand to use regional anaesthesia alone or in combination with general anaesthesia, and on the other hand to use this technique for pain management also in the postoperative period.

A main goal is the maintenance of cardiovascular stability in high-risk patients during surgery. For this purpose the choice of anaesthetics is of relevance as well as the use of an adequate monitoring. Currently, invasive methods such thermodilution via pulmonary artery catheterization and pulse contour analysis are available, but also non invasive techniques, such as transesophageal echocardiography (TEE). Most of these methods are, however, expensive and require specialised personnel. TEE seems to be the most advantageous monitoring method because new regional wall motion abnormalities associated with myocardial ischaemia can be detected early and reliably. However, which method is used during the operative setting depends on several conditions, such as type of anaesthesia and surgery, patient related factors and the expertise of the anaesthesiologist.

Patients with pacemakers or implantable cardioverter defibrillators are especially at risk of haemodynamic alterations during the perioperative period. Issues that need to be addressed in these patients include guidance on the identification of normal and abnormal device function and the recognition and avoidance of potential hazards in the medical environment. Therefore, the anaesthetist should be informed about the specifications of the device and especially programmed settings (e. g. mode and rate). However, to date there are no sufficient informations concerning the most appropriate type of anaesthesia or monitoring in these patients.

Cardiovascular alteration is one of the most frequent causes for morbidity and mortality in Germany. Survival of these patients depends on the time delay before professional help arrives and sufficient resuscitation has been initiated. Adult Basic Life Support (BLS) guidelines support the inclusion of the use of the Automated External Defibrillator (AED), as part of Basic Life Support (BLS). In this mini symposium the preclinical treatment of patients with sudden cardiac arrest by use of AED is extensively presented and discussed.

Anaesthesiological knowledge and experience in perioperative treatment of patients with and/or at risk of cardiac diseases have been sufficiently increased during the past years. However, further efforts have to be performed to increase patient’s safety in future. This includes a consequent preoperative risk evaluation, perioperative β-blockade as well as a more frequent use of thoracic epidural anaesthesia/analgesia.

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