Perioperative antiplatelet therapy: the case for continuing therapy in patients at risk of myocardial infarction

Recent clinical data show that the risk of coronary thrombosis after antiplatelet drugs withdrawal is much higher than that of surgical bleeding if they are continued. In secondary prevention, aspirin is a lifelong therapy and should never be stopped. Clopidogrel is regarded as mandatory until the coronary stents are fully endothelialized, which takes 3 months for bare metal stents, but up to 1 yr for drug-eluting stents. Therefore, interruption of antiplatelet therapy 10 days before surgery should be revised. After reviewing the data on the use of antiplatelet drugs in cardiology and in surgery, we propose an algorithm for the management of patients, based on the risk of myocardial ischaemia and death compared with that of bleeding, for different types of surgery. Even if large prospective studies with a high degree of evidence are still lacking on different antiplatelet regimens during non-cardiac surgery, we propose that, apart from low coronary risk situations, patients on antiplatelet drugs should continue their treatment throughout surgery, except when bleeding might occur in a closed space. A therapeutic bridge with shorter-acting antiplatelet drugs may be considere

Preoperative evaluation of patients with, or at risk of, coronary artery disease undergoing non‐cardiac surgery

The increasing number of patients with coronary artery disease undergoing major non‐cardiac surgery justifies guidelines concerning preoperative evaluation, stress testing, coronary angiography, and revascularization. A review of the recent literature shows that stress testing should be limited to patients with suspicion of a myocardium at risk of ischaemia, and coronary angiography to situations where revascularization can improve long‐term survival. Recent data have shown that any event in the coronary circulation, be it new ischaemia, infarction, or revascularization, induces a high‐risk period of 6 weeks, and an intermediate‐risk period of 3 months. A 3‐month minimum delay is therefore indicated before performing non‐cardiac surgery after myocardial infarction or revascularization. However, this delay may be too long if an urgent surgical procedure is requested, as for instance with rapidly spreading tumours, impending aneurysm rupture, infections requiring drainage, or bone fractures. It is then appropriate to use perioperative beta‐block, which reduces the cardiac complication rate in patients with, or at risk of, coronary artery disease. The objective of this review is to offer a comprehensive algorithm to help clinicians in the preoperative assessment of patients undergoing non‐cardiac surgery. Br J Anaesth 2002; 89: 747-5

Off‐pump coronary artery bypass surgery: physiology and anaesthetic management†

Increasing interest is being shown in beating heart (off‐pump) coronary artery surgery (OPCAB) because, compared with operations performed with cardiopulmonary bypass, OPCAB surgery may be associated with decreased postoperative morbidity and reduced total costs. Its appears to produce better results than conventional surgery in high‐risk patient populations, elderly patients, and those with compromised cardiac function or coagulation disorders. Recent improvements in the technique have resulted in the possibility of multiple‐vessel grafting in all coronary territories, with a graft patency comparable with conventional surgery. During beating‐heart surgery, anaesthetists face two problems: first, the maintenance of haemodynamic stability during heart enucleation necessary for accessing each coronary artery; and second, the management of intraoperative myocardial ischaemia when coronary flow must be interrupted during grafting. The anaesthetic technique is less important than adequate management of these two major constraints. However, experimental and recent clinical data suggest that volatile anaesthetics have a marked cardioprotective effect against ischaemia, and might be specifically indicated. OPCAB surgery requires team work between anaesthetists and surgeons, who must be aware of each other's constraints. Some surgical aspects of the operation are reviewed along with physiological and anaesthetic data. Br J Anaesth 2004; 92: 400-1

Fatal myocardial infarction after lung resection in a patient with prophylactic preoperative coronary stenting†

In this report we present the case of a 77-yr-old man who underwent resection of the upper lobe of the left lung for a carcinoma, six weeks after percutaneous transluminal coronary angioplasty (PTCA) with stenting of the left anterior descending (LAD) and circumflex coronary arteries. Antiplatelet therapy with clopidogrel was interrupted two weeks before surgery to allow for epidural catheter placement and to minimize haemorrhage. The surgical procedure was uneventful. In the immediate postoperative period, however, the patient suffered severe myocardial ischaemia. Emergency coronary angiography showed complete thrombotic occlusion of the LAD stent. In spite of successful recanalization, reinfarction occurred and the patient died in cardiogenic shock. Prophylactic preoperative coronary stenting may put the patient at risk of stent thrombosis if surgery cannot be postponed for three months. In such cases, other strategies such as perioperative β-blockade for preoperative cardiac management should be considered. Br J Anaesth 2004; 92: 743-

The effect of insulin on cardiac autonomic balance predicts weight reduction after gastric bypass

Aims/hypothesis: The aim of this study was to assess the predictive role of autonomic reactivity in body weight loss induced by gastric bypass. Methods: A group of 22 morbidly obese subjects, who were due to undergo a gastric bypass, were submitted, before surgery, to a euglycaemic-hyperinsulinaemic clamp, during which a continuous recording of the ECG was performed. The effect of insulin on cardiac autonomic balance was evaluated by performing power spectral analysis of heart rate variability. The low-to-high frequency ratio was calculated before and during the clamp and its modifications were expressed as % delta low-to-high frequency ratio (%Δ L: H). Results: Preoperative %Δ L: H showed a significant (p=0.0009, r 2=0.43), positive relationship to the reduction of body weight, measured 1 year after surgery and expressed as % excess weight loss (% EWL). Preoperative BMI was also significantly (p=0.0009, r 2=0.43) negatively related to the 12-month % EWL. In a multiple regression analysis, %Δ L: H remained a significant (p=0.003), independent predictor of body weight loss, even when preoperative BMI or age, % fat mass, insulinaemia and glucose disposal were taken into account. Conclusions/interpretation: The best correction of excess body weight was achieved by those obese subjects who had a preserved capacity to shift their cardiac autonomic balance towards a sympathetic prevalence in response to an euglycaemic-hyperinsulinaemic clamp. Further studies are needed to elucidate the mechanisms through which the autonomic nervous system influences weight reductio

Off-pump coronary artery bypass surgery: physiology and anaesthetic management

Increasing interest is being shown in beating heart (off-pump) coronary artery surgery (OPCAB) because, compared with operations performed with cardiopulmonary bypass, OPCAB surgery may be associated with decreased postoperative morbidity and reduced total costs. Its appears to produce better results than conventional surgery in high-risk patient populations, elderly patients, and those with compromised cardiac function or coagulation disorders. Recent improvements in the technique have resulted in the possibility of multiple-vessel grafting in all coronary territories, with a graft patency comparable with conventional surgery. During beating-heart surgery, anaesthetists face two problems: first, the maintenance of haemodynamic stability during heart enucleation necessary for accessing each coronary artery; and second, the management of intraoperative myocardial ischaemia when coronary flow must be interrupted during grafting. The anaesthetic technique is less important than adequate management of these two major constraints. However, experimental and recent clinical data suggest that volatile anaesthetics have a marked cardioprotective effect against ischaemia, and might be specifically indicated. OPCAB surgery requires team work between anaesthetists and surgeons, who must be aware of each other's constraints. Some surgical aspects of the operation are reviewed along with physiological and anaesthetic data

Hemodynamics optimization during off-pump coronary artery bypass: the 'no compression' technique

OBJECTIVE: Heart manipulation during OPCAB may cause hemodynamical instability in particular for access to the posterior and lateral walls. The 'no compression' technique involves enucleation of the heart without any compression on the cavities, and stabilization of the target area with a suction device. The impact of this technique on hemodynamics is assessed. METHODS: In order to analyze a homogeneous group, 26 consecutive patients with triple grafts, one to each side of the heart in the same sequential order (posterior, lateral and anterior wall successively) were selected. Heart rate (HR), mean pulmonary arterial pressure (PAP, mmHg), pulmonary capillary wedge pressure (PCWP, mmHg), mean arterial pressure (MAP, mmHg), cardiac output index (COI, l/min per m(2)), and central venous saturation (SvO(2),%) were monitored. A coronary shunt was used for all the anastomoses. RESULTS: HR was stable with baseline value of 60+/-10 and the highest value for the anterior wall, 63.6+/-8 (P=0.23). PAP and PCWP exhibited their highest increase, when compared with baseline, for the lateral wall, 23.9+/-4.7 vs. 20.7+/-6.2 (P=0.06), and 17.2+/-4.7 vs. 14.9+/-5.6 (P=0.16), respectively. MAP, COI and SvO(2), exhibited their largest drop, when compared with baseline, for the lateral wall too, 73.1+/-9.1 vs. 77.1+/-7.5 (P=0.12), 1.99+/-0.47 vs. 2.26+/-0.55 (P=0.09), and 70.5+/-8.4 vs. 74.8+/-9.3 (P=0.12), respectively. CONCLUSIONS: None of the hemodynamical parameter differed significantly from baseline value for all three territories. While hemodynamics was perfectly maintained during the posterior and anterior walls revascularization, exposure of the lateral wall led to marginal changes only

Fatal myocardial infarction after lung resection in a patient with prophylactic preoperative coronary stenting.

In this report we present the case of a 77-yr-old man who underwent resection of the upper lobe of the left lung for a carcinoma, six weeks after percutaneous transluminal coronary angioplasty (PTCA) with stenting of the left anterior descending (LAD) and circumflex coronary arteries. Antiplatelet therapy with clopidogrel was interrupted two weeks before surgery to allow for epidural catheter placement and to minimize haemorrhage. The surgical procedure was uneventful. In the immediate postoperative period, however, the patient suffered severe myocardial ischaemia. Emergency coronary angiography showed complete thrombotic occlusion of the LAD stent. In spite of successful recanalization, reinfarction occurred and the patient died in cardiogenic shock. Prophylactic preoperative coronary stenting may put the patient at risk of stent thrombosis if surgery cannot be postponed for three months. In such cases, other strategies such as perioperative beta-blockade for preoperative cardiac management should be considered