Cardio-protection with intra-aortic counter-pulsation for thoracic surgery
Article Outline
Summary
A significant number of patients undergoing non-cardiac surgery are at risk of cardiac complications including myocardial infarction and cardiac-related death. There is still ongoing debate about the most appropriate management when faced with a pre-operative patient with coronary artery disease. We present the case of a 70-year old male with significant coronary artery disease and left ventricular systolic dysfunction who unfortunately was also diagnosed with a non-small cell lung cancer and required surgical intervention. The management with the use of the intra-aortic balloon pump (IABP) for cardio-protection is discussed.
Keywords: Lung cancer, Ischaemic heart disease, IABP
Introduction
Annually, worldwide, an estimated 0.5% (500,000) of the 100 million adults undergoing non-cardiac surgery dies during the peri-operative phase due to cardiac disease1 with 1.1 million patients experiencing a myocardial infarction (MI).2 Although the patho-physiology of peri-operative MI is not entirely clear, coronary plaque rupture and thrombus formation during the hyper-coagulable status of the peri-operative period is responsible in 50% of all fatal MI while in the remaining 50% there is a sustained oxygen supply/demand mismatch.3
We describe the use of the intra-aortic balloon counter-pulsation therapy (IABP) as a management strategy for a patient with ischaemic heart disease undergoing lung cancer surgery.
Case report
A 70-year old male was referred for coronary artery bypass surgery (CABG). His risk factors included hypertension, hypercholesterolemia and 35-pack year current smoker. Angiography confirmed triple vessel coronary artery disease (CAD) with impaired left ventricular (LV) function (ejection fraction: 40%). Pre-operative, chest radiography revealed 1.7
cm opacity in right mid zone. Further investigation with CT scan confirmed a 20×14mm nodule in posterior segment in right upper lobe abutting the fissure as well as right lower para-tracheal lymphadenopathy. PET scan staged the lesion as T1N2M0 disease.
Attempts at confirming the staging by trans-bronchial fine needle aspiration were unsuccessful. He was therefore scheduled for mediastinoscopy and biopsy of para-tracheal lymph nodes and should these be negative on frozen section, then to proceed to lobectomy within the same anaesthetic.
The options for cardio-protection included beta blockade, revascularisation pre-biopsy or cardio-protection with an intra-aortic balloon pump (IABP). Due to the significant impairment of LV function as well as coronary artery disease, it was felt that beta-blockade alone might not provide adequate cardio-protection. On the other hand, this patient could potentially have stage IIIB lung cancer and hence revascularization with CABG would be inappropriate. PCI could have been an option but only bare-metal stents would be indicated and he would have been at a higher risk of myocardial injury for the subsequent 6 weeks with risk of disease (lung cancer) progression.
IABP was chosen after assessing the above risks and benefits and was inserted 12h pre-op.
Unfortunately frozen section confirmed N2 disease (station 4R). The patient underwent an uneventful procedure. The IABP was removed 12h postoperatively. He was discharged home the evening after IABP removal. He was then reviewed the next day by the oncologist to discuss and plan further therapy.
Discussion
Currently, there is no established evidence to support the management strategies in patients at risk of myocardial damage and who are undergoing non-cardiac surgery. Surgeons are guided by AHA/ACC guidelines.4 The armamentarium available for peri-operative cardio-protection includes medical optimization with beta-blockers and coronary artery revascularisation either by percutaneous coronary intervention (PCI) or CABG.
These assess the risks of myocardial injury in terms of the patient characteristics and surgical procedure to be undertaken.
The patient described above, was classed as being at high risk due to triple vessel CAD in association with impaired LV, his age and other co-morbidities such as hypertension and current smoker.
The initial thought was to optimize his beta-blockade therapy. However, the evidence for this strategy is still under debate. The benefits of beta-blockade were confirmed in the meta-analysis by Auerbach and Goldman.5 They analyzed the results of five studies (n=685 patients) and reported that an episode of significant myocardial ischaemia is avoided for every sixth patient treated with a B-blocker compared to placebo in patients undergoing non-cardiac surgery. Moreover, a database review by Lindenauer et al.6 showed that, in a group of over 500,000 patients, peri-operative beta-blocker therapy was associated with a reduced risk of in-hospital death among high-risk, but not low-risk, patients undergoing major non-cardiac surgery.
However, the benefits of peri-operative B-blockers remain uncertain as published in another meta-analysis recently.7 Review of the effects of B-blockers from 22 studies (nearly 2500 patients) did not show any significant reduction in cardiovascular mortality, non-fatal myocardial infarction, and non-fatal cardiac events.
The recommendation from the AHA/ACC in terms of coronary revascularization by CABG is relatively straight forward.4 If a patient, is not a surgical candidate for CABG on either prognostic or symptomatic grounds,8 then surgical coronary revascularisation is not indicated irrespective of the need for non-cardiac surgery.4, 8 However, in the case that is described above, his initial referral was for CABG but the lung lesion was picked up pre-operatively. However, the lung pathology could be a Stage IIIB tumour in which case CABG would not be appropriate.
The use of intra-aortic counter-pulsation adds to the management armamentarium for this category of patients. IABP insertion is associated with a very low morbidity (around 3%) and mortality (<1%) in our unit. It provides effective myocardial protection by improving coronary artery blood flow during the diastolic augmentation and reduces myocardial oxygen demand in systole by reducing the afterload. The drawback of IABP is that it does not reduce tachycardic episodes during the peri-operative phase and that they do carry an increased risk of morbidity especially in non-expert hands. However, IABP can be used in conjunction with B-blockers for optimal benefit.
Conflict of interest statement
None of the authors have a conflict of interest to declare in relation to this work.
References
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PII: S1755-0017(07)00017-6
doi:10.1016/j.rmedc.2007.10.008
© 2007 Elsevier Ltd. All rights reserved.
