Case 1, a 62-yr-old, 64 kg man was to undergo thoracotomy and left upper lobectomy for lung carcinoma. He gave a history of angina and coronary angiogram showed extensive three-vessel disease with right coronary artery totally occluded, left anterior descending artery 80% stenosed and a small left circumflex artery. Left ventricular ejection fraction was 25%. Given the diffuse nature of the disease, the patient was not felt to be suitable for coronary artery bypass surgery. Balanced anaesthesia was planned and intra-aortic balloon pump (IABP) was used for perioperative myocardial support. IABP was inserted via the femoral artery with local anaesthesia. Anaesthesia was induced with fentanyl 300 µg, midazolam 2 mg, and thiopentone 75 mg and rocuronium 50 mg. Maintenance of anaesthesia was with oxygen and air, sevoflurane 12%, morphine and atracurium. Thoracotomy and left upper lobectomy was performed under one-lung anaesthesia. There was transient ST depression on the electrocardiogram shortly after induction of anaesthesia which resolved spontaneously. Throughout the remainder of the case the blood pressure, heart rate and ECG remained within normal limits. Total blood loss was estimated to be 200 ml. Intercostal nerves block was performed by surgeon with plain bupivacaine 0.5%, 20 ml and diclofenac 50 mg was given rectally at the end of surgery. Postoperative pain relief was continued with patient-controlled analgesia with morphine. IABP was removed on the second postoperative day. Serial ECG and cardiac enzymes were normal. The patient was discharged from the hospital on postoperative day 10.
Case 2, a 70-yr-old, 75 kg man scheduled for thoracotomy and right upper lobectomy. He gave a history of hypercholesterolaemia, hypertension and a previous myocardial infarction. Coronary angiography showed extensive three-vessel disease: left main stem and left circumflex arteries were 50% stenosed, left anterior descending and right coronary artery were totally occluded. Echocardiography showed akinesis in the apex, hypokinetic antero-septal, mild diastolic dysfunction and a normal ejection fraction. Balanced anaesthetic management was planned and IABP was inserted preoperatively. Anaesthesia was induced with fentanyl 300 µg, midazolam 2 mg, propofol 40 mg and rocuronium 60 mg. Anaesthesia was maintained as in the previous case. Surgery was uneventful with blood loss estimated to be 250 ml. Intercostal nerves block was performed by surgeon with plain bupivacaine 0.5%, 20 ml. The patient was extubated at the end of surgery, diclofenac suppository 50 mg was given rectally and postoperative pain relief was maintained using patient-controlled analgesia with morphine. Serial cardiac enzymes were not elevated. The patient was discharged from the hospital on postoperative day 15.
The IABP is inflated during diastole, thus increasing the diastolic pressure, leading to enhanced myocardial perfusion. In systole, the balloon is deflated, reducing afterload and myocardial consumption, and increasing cardiac output. It has been used mainly in patients with persistent cardiac failure after cardiopulmonary bypass, refractory angina or after myocardial infarction. However, indications for its application continue to evolve. It has been suggested as a method of decreasing the risk of cardiac complications in patients with ischaemic heart disease who are undergoing non-cardiac surgery.
In our report, both patients had extensive three-vessel coronary artery disease with operable lung cancer, it was felt that delaying surgery for coronary revascularization was difficult to justify. In addition, the anatomy of the first patient was not amendable to surgery. Thus we decided to conduct the anaesthetic management with the support of IABP, in addition to aggressive perioperative haemodynamic management and optimal pain relief. We also felt that despite the small increased risk of bleeding and having to forgo the advantages of epidural analgesia, it is more important to continue the antiplatelet therapy.
In previous reports, there have been no intra-operative deaths while the IABP is in situ but problems have arisen when the pump has been removed. However, the correct time for removal is unclear. A period of 6 days has been suggested, as the risk of a myocardial infarction can persist until the fifth or sixth postoperative day, but prolonged mechanical support may be associated with IABP perforation and entrapment.4 In our patients, we removed the IABP on the second postoperative day because of the stable haemodynamic status and to avoid potential morbidity of IABP.
In conclusion, we reported the successful anaesthetic management of two patients with severe cardiac disease undergoing major non-cardiac surgery with the support of IABP. We agreed with Marcucci and colleagues1 and Newby and Nimmo2 that aggressive antiplatelet therapy and haemodynamic protective measures such as ß-blockade and optimal pain control are needed in these high risk patients. However, it is also important to remember that IABP can be used to support high risk patients undergoing non-cardiac surgery and may be influential in the prevention of perioperative cardiac complications and death.
Kuala Lumpur, Malaysia
EditorWe would like to congratulate the authors for the high standard of care and their concern for the patients well being, and we recognize that the mechanical support to the heart provided by an IABP may be of invaluable benefit to the patient with severe coronary artery disease and poor left ventricular function, undergoing non-cardiac surgery. We would, though, like to underline some important elements.
In their letter, the authors do not specify whether they treated the patients with ß-receptor antagonists or whether they chose not to. We stress that IABP can not replace ß-receptor blockade. The benefits of the latter in preventing perioperative cardiac complications in high risk patients have been proven,5 and their perioperative use is recommended in all patients presenting with one or more risk factors correlated with higher risk of cardiac complications.6 Perioperative and long-term ß-blocker therapy has further been shown to be beneficial in patients presenting the classical contraindications as obstructive pulmonary disease, diabetes mellitus and peripheral vascular disease, and even patients with chronic heart failure and low left ventricular ejection fraction benefit from ß-receptor blockers if initiated at low doses.7 8
Apart from protecting the patient's ischaemic heart from the deleterious effects of tachycardia, ß-blockers show several other cardioprotective properties and may reduce the stress response.8
Although IABP is very efficacious in reducing myocardial oxygen demand and increasing coronary perfusion pressure, it does not prevent tachycardia and does not modulate the neuro-endocrine stress response caused by surgery. Withdrawal of the IABP support in the postoperative period puts the patient at risk of an imbalance between oxygen delivery and oxygen demand if the myocardium is not otherwise protected.
Anaesthesia was maintained with sevoflurane in both cases. This strategy will doubtlessly have contributed to cardiac protection by preconditioning of the myocardium against ischaemia, a well established property of this volatile anaesthetic.9
Finally, as the authors state, IABP is an invasive procedure with non-negligible complications that often requires anticoagulant therapy. In selected cases it can be a valuable adjunct to a global strategy of myocardial protection, but ß-receptor antagonism and myocardial preconditioning should form the basis of the perioperative care given to a patient at risk of myocardial ischaemia.
Lausanne, Switzerland
References
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