**24. Conclusion**

The IABP since its advent in 1960 has progressively become an indispensable technology available to the healthcare team in cardiology and cardiac surgery. Improvements in membrane technology have reduced the french sizes required to be used for femoral percutaneous insertion. This has minimized trauma caused by femoral insertion of the IAB catheter.

Earlier on in my training as a perfusionist, old school cardiac surgeons always inserted IAB's later rather than sooner. Counterpulsation technology was always thought to be a last ditch effort and mortality was thought to be higher once the IAB was inserted. This perception has changed radically over the last twenty years.

The ease of insertion (compared to VAD's and artificial lungs), ease of removal, low risk of complications and availability in the peri/post and pre-operative environment in a hospital setting has made counterpulsation an ideal choice to treat acute or chronic heart failure. There is no doubt at this point of the positive effects of counterpulsation on early mortality and post-operative morbidity in cardiac surgery. In instances where IAB insertion is

Intraoperatively, IABPs are inserted into our patients when difficulty to wean from the bypass machine is anticipated due to instability in the pre-bypass or bypass period or for failure to wean from the bypass machine, once reversible causes for the failure are ruled out. There may be a survival advantage to placing the IABP prior to coming off bypass based on one review. Delaying insertion of the IABP in the unstable perioperative patient who is unresponsive to reasonable doses of inotropes or who has rapidly accelerating inotropic requirements may have deleterious effects. Theoretically this is supported by the following facts. High inotropic doses increase myocardial inotropy and tension resulting in increased myocardial oxygen demands. Impaired diastolic relaxation and increased ectopy and afterload, as seen with certain inotropes, may further tip the myocardial supply/demand balance in favour of demand (*Katz AM 1990*). Myocardial injury may be further exacerbated by the inotropes increased delivery of calcium to the cell, overcoming the ischemic myocardium's presumed protective attempt at limiting available calcium. Early insertion of the IABP in the unstable post-bypass patient appears to theoretically and anecdotally

Postoperative insertion of the IABP in the majority of our cases is for myocardial failure or signs of ischemia. Many times there is a dramatic improvement post balloon insertion. The mechanism producing this improvement is often not clear .Possibilities include a heightened diastolic pressure overcoming decreased coronary flow secondary to low mean arterial pressure, left internal mammary spasm or air within a coronary artery, improved collateral flow (Kern MJ 1991), or decreased demands secondary to decreased afterload and preload resulting in decreased myocardial wall tension. The IABP often assists in stabilization of the patient, although more definitive therapy may be required. The location of the ischemia, as visualized by the electrocardiogram and often echocardiogram, the magnitude of the failure, the surgical knowledge of the coronary disease and surgery and the response to the IABP

We have come to use IABP's earlier, and the indications have broadened to include all stages of the perioperative care. The theoretical protective effect of the IABP with respect to the myocardial supply/demand ratio, the ease of insertion of the IABP by the percutaneous

The IABP since its advent in 1960 has progressively become an indispensable technology available to the healthcare team in cardiology and cardiac surgery. Improvements in membrane technology have reduced the french sizes required to be used for femoral percutaneous insertion. This has minimized trauma caused by femoral insertion of the IAB

Earlier on in my training as a perfusionist, old school cardiac surgeons always inserted IAB's later rather than sooner. Counterpulsation technology was always thought to be a last ditch effort and mortality was thought to be higher once the IAB was inserted. This

The ease of insertion (compared to VAD's and artificial lungs), ease of removal, low risk of complications and availability in the peri/post and pre-operative environment in a hospital setting has made counterpulsation an ideal choice to treat acute or chronic heart failure. There is no doubt at this point of the positive effects of counterpulsation on early mortality and post-operative morbidity in cardiac surgery. In instances where IAB insertion is

improve outcome (*Poole Wilson PA 1990*).

determine the need for further management.

**24. Conclusion** 

catheter.

route clinical observations and limited studies support this practice.

perception has changed radically over the last twenty years.

precluded or insertion has failed, transthoracic (in a peri-operative setting), transbrachial or subclavian insertion can also be performed with a positive impact on survival. Morbidity and mortality however are higher in these kinds of cases and may have to do with the preoperative risk factors these patients come into surgery for. The cardiac surgeon has to tread the fine line between deciding the optimal timing for IAB insertion by weighing the benefits of counterpulsation vs the low risk of complications. It is increasingly being understood that for a poor LV and /or a patient with a risk of peri-operative infarct, it is optimal to insert an IAB sooner rather than later. The catheter can easily be removed first or second postoperative day after the surgery has performed and the risk for infarct been mitigated.

At Southlake, a 380 bed community hospital, we perform approximately 1000 heart surgeries and 3000 PTCA's annually. In support we insert 250 IAB catheters annually and are the largest IAB user in Ontario-Canada. We are a comparatively new heart centre, having started our cardiac surgery program in 2004. Aggressive use of counterpulsation reflects the new belief in early IAB insertion in cardiac patients at risk of pre, peri or post-operative infarct. Transfusion rates at SRHC for CABG in the first half of 2009 approximate 26% (Fig 26).

Fig. 26. Red Blood Cell Transfusion Rate for 2009 at SRHC.

Mortality at SRHC for late 2009 (July to Dec 2009) was based on Toronto Risk Score (TRS). The observed mortality ranged from 0.5% (TRS 2-4) to 8.5% (TRS >8) as shown in fig 27.


Fig. 27. Observed and Expected Mortality at SRHC by Toronto Risk Score

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It is the opinion of the authors that the above average results in morbidity and mortality for our cardiac patients may partly be due to the aggressive use of IAB in cardiac procedures. Aggressive use of counterpulsation therapy preempts infarction for the cardiac patient and in turn improves outcomes in cardiac surgery.

### **25. Acknowledgement**

I would like to thank Maquet cardiovascular LLC (formerly Datascope) for providing most of the figures and pictures from their educational archives. I would also like to thank Maquet International who funded the editing costs of printing this chapter.
