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J Thorac Cardiovasc Surg 1997;114:1128-1129
© 1997 Mosby, Inc.
LETTERS TO THE EDITOR |
Department of Cardiothoracic Surgery
Department of Clinical Perfusion
Yorkshire Heart Centre
Leeds General Infirmary and Killingbeck Hospital
Leeds LS14 6UQ, United Kingdom
12/8/84307
To the Editor:
We read with interest the article by Torchiana and associates
1 in the April 1997 issue of this Journal regarding trends in practice and outcome of intraaortic balloon (IAB) pumping for cardiac support. Using the strategy of preoperative insertion of the IAB, several other groups have also shown improvement in survival and reduced morbidity from perioperative infarction. 2-4 In many centers an IAB is now electively inserted in the preoperative period for indications such as evolving myocardial infarction, refractory unstable angina, failed percutaneous transluminal angioplasty necessitating emergency myocardial revascularization, complication of myocardial infarction with cardiogenic shock, or redo operations. 3-5 Very little, however, is mentioned about the continuation of IAB counterpulsation during cardiopulmonary bypass (CPB). If an IAB has to be inserted before the cardiac operation is begun, we prefer to continue counterpulsation throughout the operation. Counterpulsation is continued even during the period of aortic crossclamping on the intrinsic rate of the IAB and with 20% less than full augmentation. Once the heart starts ejecting, IAB counterpulsation can be synchronized with left ventricular diastole, unlike counterpulsation with conventional pulsatile pumps, to augment diastolic pumping and decrease systolic impedance. We temporarily stop the IAB pump only when clamping or unclamping the aorta.
Many surgeons stop IAB counterpulsation as soon as CPB is resumed, and counterpulsation is restarted while weaning the patient from CPB. We sent a questionnaire to 46 centers performing adult cardiac surgery in the United Kingdom and Ireland. From the 36 replies (78.2%) that we received, all surgeons at 29 centers (80.5%) stop IAB counterpulsation on commencing CPB. At one center the IAB pump is set on minimum volume and frequency, mainly to reduce the risk of clotting. At the remaining six centers counterpulsation is continued during CPB by all surgeons except one. It seems that not many surgeons make use of the potential advantages of having the IAB already in situ during CPB.
IAB counterpulsation effectively minimizes ischemic myocardial damage during induction of general anesthesia and during the pre-CPB period while conduits are being harvested. 2, 6 On initiation of CPB, systemic perfusion is maintained with reduced preload, which reduces myocardial oxygen needs significantly. The use of IAB counterpulsation during this period of CPB reduces afterload and also improves myocardial oxygen delivery. 7 Another potential benefit of IAB counterpulsation during CPB is pulsatile perfusion. The use of IAB counterpulsation as a simple method of achieving pulsatile flow during CPB was elucidated by Pappas and associates 7 in 1975. This may result in better organ function 8, 9 by the mechanism, not simply because of pulsatile flow but as an effect of the passive distention of the peripheral vascular bed owing to the propagation of the IAB-augmented diastolic pressure through the arterial system. 10 Combining IAB counterpulsation and CPB fulfils the need for greater hemodynamic support by pulsatile flow during diastole and unloading of the left ventricle during systole. 11 The patients in whom the use of IAB pumping is indicated before the operation are in a low cardiac output state. The renal and gastrointestinal perfusion in many of these patients is also suboptimal. Over recent years the importance of gastrointestinal perfusion has been more widely recognized with regard to patients in shock. 12 IAB counterpulsation may help to reduce CPB-induced gut mucosal hypoperfusion, thus avoiding intestinal ischemia and subsequent endotoxemia.
Today the IAB pump is the most widely used circulatory assist device. Improvement in its ease of insertion, safety, rapid applicability, and ability to provide adequate support in a low cardiac output syndrome has widened its use. IAB counterpulsation is an effective method of protecting the myocardium in the perioperative period and reducing organ dysfunction during CPB. However, as our survey revealed, the majority of cardiac surgeons in the United Kingdom do not fully use the benefits of IAB pulsatility during CPB. On the basis of available literature, we advocate continued counterpulsation during the whole of CPB.
References
This article has been cited by other articles:
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  S. R. Hosmane and A. G. Dawson In patients coming to theatre with an intra aortic balloon pump, is it better to turn it off or keep it on while on bypass? Interact CardioVasc Thorac Surg, September 1, 2010; 11(3): 314 - 321. [Abstract] [Full Text] [PDF]
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 F. Kawahara, Y. Kadoi, S. Saito, D. Yoshikawa, F. Goto, and N. Fujita BALLOON PUMP-INDUCED PULSATILE PERFUSION DURING CARDIOPULMONARY BYPASS DOES NOT IMPROVE BRAIN OXYGENATION J. Thorac. Cardiovasc. Surg., August 1, 1999; 118(2): 361 - 366. [Abstract] [Full Text] [PDF]
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M. Kurusz, S. D. Lick, and V. R. Conti Air embolism with intraaortic balloon counterpulsation during cardiopulmonary bypass J. Thorac. Cardiovasc. Surg., June 1, 1998; 115(6): 1393 - 1393. [Full Text]
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