**21. Advancements in IAB catheter and IAB console technology**

Considerable improvements have been made in IAB catheter and console technology in the more than 40 years since counterpulsation was introduced to clinical practice. Early IABP consoles required intensive user intervention, as all aspects of console operation were manually controlled. Early IAB catheters were 12 Fr. and required surgical insertion via a cutdown to the femoral artery. Surgical insertion could take 1-2 hours and complication rates were high. In 1979, IAB catheter insertion improved significantly with the development of percutaneous IAB insertion. Insertion time was reduced, typically to 15 minutes.

Additional improvements to the catheter in the early years included the addition of an inner lumen to facilitate wire-guided insertion and the lumen could then be used to monitor the arterial blood pressure. Prefolding of the membrane during manufacturing eliminated the need for the clinician to wrap the membrane prior to insertion through the introducer sheath. Catheters were also made smaller, from 12 Fr. to 10.5 Fr. and then to 9.5 Fr. Catheters are now 7 and 7.5 Fr. and this has helped reduce the incidence of limb ischemia to less than 3%. Reducing the catheter shaft diameter required a significant change to the way catheters were designed. With early dual lumen catheters, the inner lumen used for wire guiding the insertion and monitoring the arterial pressure was a separate catheter within the balloon catheter gas lumen. With the development of a co-lumen design where the two lumens of the catheter were extruded together with the inner and outer lumens sharing a common wall, the catheter diameter was reduced while maintaining the gas shuttle lumen and maximizing the inner lumen to accommodate the largest guide wire possible. The range of balloon membrane sizes was also expanded over the years from 40 cc in the early days of counterpulsation to 25 cc, 34 cc, 40 cc, and 50 cc IAB membranes. The size of balloon used is determined by patient height. The most recent improvement in IAB catheter technology has been the addition of a fiber optic pressure sensor to acquire the arterial pressure signal. This technology is immune to artifact, resulting in a high fidelity arterial pressure waveform for accurate IAB timing.

While innovations in IAB catheter technology were being developed, improvements in IAB console technology were also occurring. Major improvements to the console over the years

Intra-Aortic Balloon Counterpulsation Therapy

hemodynamic stress during PCI.

post-operative period (*Christenson 1997*).

**23. Counterpulsation – An anesthesiologists perspective** 

fatal.

*JC 2006*).

and Its Role in Optimizing Outcomes in Cardiac Surgery 67

4. Survival Dependent vessel: Any one artery supplying a sufficient amount of myocardium such that (in the opinion of the cardiologist) closure of the vessel would be

It should be noted that there is considerable practice variation with Intra-aortic balloon support during high risk coronary intervention. Recognizing the higher risk of access related and other vascular complications with its insertion, some clinicians prefer to have the IABP readily available and use it only if hemodynamic compromise develops. . One trial conducted in centers in the United Kingdom, The Balloon Pump-Assisted Coronary Intervention Study, assessed whether routine intra-aortic balloon pump insertion, prior to PCI, reduced the risk of major adverse cardiac and cardiovascular events in patients with severe left ventricular dysfunction and advanced coronary disease. The results of this trial involving just over 300 randomized patients did not support routine use, given no difference between the groups. Clinical judgment is certainly exercised in situations (such as those described above) where the IABP is inserted "pre-emptively", with anticipated

As an anaesthetist, working in the perioperative care of cardiac surgery patients for the last 20 years, I have observed a significant change in the attitudes and uses of the intra aortic balloon pump. I have watched the use of the IABP change from a last resort salvage technique for the patient on maximal inotropes with low output syndrome and a dismal prognosis, to a first line tool aiming for preservation of myocardial tissue in unstable cardiac surgery patients. The presumed IABP's favorable myocardial oxygen supply/demand profile and the ease of percutaneous insertion have been instrumental in this change (*Trost* 

In our institution IABPs are often inserted in preoperative cardiac surgery patients: who are experiencing unstable angina, especially post myocardial infarction, not responsive to standard non-invasive therapies; that have low output syndrome or congestive heart failure secondary to severe left ventricular dysfunction or mechanical complications such as a ventricular septal defect or mitral regurgitation induced by a myocardial infarction ; and rarely who have acute myocardial ischemia causing intractable arrhythmias. It appears that the earlier the balloon is placed in a hemodynamically struggling patient, the more stable the patient is in the post-operative period. This practice is consistent with the Task Force on Practice Guidelines of the American Heart Association and American College of Cardiology (*Ryan TJ 1999*). Frequently, IABPs are inserted for preoperative cardiac surgery patients with symptomatic left main disease. The intention of the IABP is the preservation of viable ïschemic myocardial tissue. The mechanism of the preservation may relate more to decreased myocardial demand and collateral flow as Kimura showed that in the presence of a coronary artery stenosis of greater than 90% the IABP diastolic augmentation did not result in an increased post-stenotic pressure (*Kimura A 1996*). The insertion of the IABP into the aforementioned patients facilitates the anaesthetist's ability to maintain cardiovascular stability and a favourable myocardial oxygen supply/delivery ratio at induction, maintenance and release from bypass. Replace with" The importance and validity of the IABP in maintaining a favorable myocardial oxygen supply/demand ratio is realized in the

have been aimed at making the algorithms smarter, the pneumatics faster, and the consoles smaller and lighter. Early consoles required constant operator intervention to maintain optimal triggering and timing. Improvements to the algorithms in the console resulted in the automation of timing so that once the operator established the initial timing, the console could adjust the timing for changes in patient heart rate and rhythm. Console pneumatic improvements reduced IAB inflation and deflation time, which was important for tracking tachycardic rhythms. Consoles were made smaller and lighter to facilitate transport by aircraft or ambulance.

The most significant improvement to console design occurred with the development of fully automated operation. With this capability, the console can automatically select the most reliable trigger and establish initial timing. It will then automatically readjust timing for changes in heart rate and rhythm, using advanced algorithms to track predictable (regular) as well as unpredictable (irregular) rhythms. The algorithms will also select an alternate trigger if the current trigger is lost. This automation, along with smaller fiber optic catheters offers the clinician the most advanced IAB counterpulsation system for optimal patient benefit.

### **22. Intra-aortic balloon pump use during percutaneous coronary angioplasty**

The Intra-aortic balloon pump (IABP) can also provide important hemodynamic support during complex percutaneous coronary intervention (PCI), both in the elective setting, and for acute coronary syndromes, including ST segment elevation myocardial infarction. Modern coronary interventions can generally be performed to a wide array of patient subsets with low risk of procedural complications. However, optimal patient outcomes in PCI require identification of higher risk patients, and attempts to modify those risks. One of the main predictors of outcomes in PCI is Left Ventricular dysfunction, i.e. Ejection fraction <30%. The availability of mechanical support helps provide "backup" or reserve during the procedure and decreases the risk of hemodynamic compromise. Typically, mechanical support is initiated prior to commencing PCI, and removed shortly after successful PCI. Intra-aortic balloon pump use results in the dual benefits of increased peak diastolic pressure, while lowering the end-systolic pressure. There is a resultant reduction in afterload (*Perera D et al,2010*) and improved coronary perfusion, which leads to improved myocardial oxygen supply, with decreased myocardial energy demands.


have been aimed at making the algorithms smarter, the pneumatics faster, and the consoles smaller and lighter. Early consoles required constant operator intervention to maintain optimal triggering and timing. Improvements to the algorithms in the console resulted in the automation of timing so that once the operator established the initial timing, the console could adjust the timing for changes in patient heart rate and rhythm. Console pneumatic improvements reduced IAB inflation and deflation time, which was important for tracking tachycardic rhythms. Consoles were made smaller and lighter to facilitate transport by

The most significant improvement to console design occurred with the development of fully automated operation. With this capability, the console can automatically select the most reliable trigger and establish initial timing. It will then automatically readjust timing for changes in heart rate and rhythm, using advanced algorithms to track predictable (regular) as well as unpredictable (irregular) rhythms. The algorithms will also select an alternate trigger if the current trigger is lost. This automation, along with smaller fiber optic catheters offers the clinician the most advanced IAB counterpulsation system for optimal patient

**22. Intra-aortic balloon pump use during percutaneous coronary angioplasty**  The Intra-aortic balloon pump (IABP) can also provide important hemodynamic support during complex percutaneous coronary intervention (PCI), both in the elective setting, and for acute coronary syndromes, including ST segment elevation myocardial infarction. Modern coronary interventions can generally be performed to a wide array of patient subsets with low risk of procedural complications. However, optimal patient outcomes in PCI require identification of higher risk patients, and attempts to modify those risks. One of the main predictors of outcomes in PCI is Left Ventricular dysfunction, i.e. Ejection fraction <30%. The availability of mechanical support helps provide "backup" or reserve during the procedure and decreases the risk of hemodynamic compromise. Typically, mechanical support is initiated prior to commencing PCI, and removed shortly after successful PCI. Intra-aortic balloon pump use results in the dual benefits of increased peak diastolic pressure, while lowering the end-systolic pressure. There is a resultant reduction in afterload (*Perera D et al,2010*) and improved coronary perfusion, which leads to improved

1. Acute Coronary Syndromes (ACS) / ST elevation Myocardial Infarction (STEMI), complicated by cardiogenic Shock, due to LV systolic dysfunction or a mechanical

complications such as acute mitral regurgitation or ventricular septal defect. 2. PCI in a coronary artery supplying a large territory of myocardium, typically with underlying Left ventricular dysfunction (practically speaking, Grade 3 or worse - EF < 30%). Specific scenarios include i) coronary intervention on a diseased vessel that also supplies flow to another occluded vessel (via channels, called collateral arteries, that fill that territory in retrograde fashion), ii) unprotected left main stenting, iii) PCI to the only patent artery iv) PCI with concomitant valvular disease, if anticipated deterioration in the valvular disease (ex. patients with at least moderate ischemic mitral

regurgitation, and planned PCI that could worsen degree of regurgitation).

heart filling pressures - pulmonary capillary wedge pressure >20mmHg.

3. If patients have clinical signs of abnormal resting hemodynamics, prior to PCI: low systolic blood pressure (SBP) <100, with objective or clinical suspicion of elevated left

myocardial oxygen supply, with decreased myocardial energy demands.

The common scenarios for IABP use in PCI include:

aircraft or ambulance.

benefit.

4. Survival Dependent vessel: Any one artery supplying a sufficient amount of myocardium such that (in the opinion of the cardiologist) closure of the vessel would be fatal.

It should be noted that there is considerable practice variation with Intra-aortic balloon support during high risk coronary intervention. Recognizing the higher risk of access related and other vascular complications with its insertion, some clinicians prefer to have the IABP readily available and use it only if hemodynamic compromise develops. . One trial conducted in centers in the United Kingdom, The Balloon Pump-Assisted Coronary Intervention Study, assessed whether routine intra-aortic balloon pump insertion, prior to PCI, reduced the risk of major adverse cardiac and cardiovascular events in patients with severe left ventricular dysfunction and advanced coronary disease. The results of this trial involving just over 300 randomized patients did not support routine use, given no difference between the groups. Clinical judgment is certainly exercised in situations (such as those described above) where the IABP is inserted "pre-emptively", with anticipated hemodynamic stress during PCI.
