Since the first successful use of an intraaortic balloon counter-pulsation pump (IABP) by Kantrowitz in 1968,1 the IABP has been applied as a life-saving method for hundreds of thousands of patients.2 Traditional insertion of the IABP is through the femoral artery, but this approach has several limitations, including restriction to bed rest, risk of limb ischemia, and risk of infection at the insertion site.3
Intraaortic balloon counter-pulsation pump placement via the subclavian artery (SCA) was first explored as an alternative approach nearly 4 decades ago,4 and offers several advantages. First, the SCA is generally free of atherosclerosis, even in patients with significant peripheral arterial disease. Second, the SCA approach allows patients to ambulate early after device insertion.3 For these reasons, an increasing number of series have supported the safety and efficacy of subclavian artery intraaortic balloon pumps (SCA-IABPs) as temporary and minimally invasive devices supporting decompensated end-stage heart failure patients as a bridge to transplantation.5–7
This study explores the safety of a prophylactic SCA-IABP as a bridge to recovery (BTR) after cardiac surgery in high-risk patients with severe ischemic cardiomyopathy and left ventricular dysfunction.
This study was conducted in accordance with the participating institutions’ Institutional Review Boards. The analysis included 11 consecutive patients at three institutions, who underwent perioperative insertion of a SCA-IABP as a bridge to cardiac recovery from November 2011 to January 2013. All patients (n = 11) had preoperative ejection fractions of 30% or less.
The primary outcome measure was a composite endpoint of device-related complications (including limb ischemia, stroke, device failure, bleeding requiring reoperation, brachial plexus injury, device-related infection, and vascular complications) and in-hospital mortality after cardiac surgery.
As previously described, the SCA is isolated through a small incision in the infraclavicular region.5 After 5,000 units of Heparin are given, a side-biting clamp is applied to the SCA. A 4 by 7 mm tapered polytetrafluoroethylene graft is used. An incision is made 8 cm from the narrowest portion and another is made 1.5 cm from the proximal end. This is to ensure that the one-way stopper slides over the distal portion and it is at the level of the skin without stretching or kinking. This is then anastomosed to the artery using 6-0 polypropolene on a small needle. Then, the one-way valve is obtained from the 8 F introducer sheath in our standard Maquet IABP catheter kit (Maquet cardiovascular datascope corp., Fairfield, NJ); the sheath is cut at the hub; the side hole is cut off; the inner metal coil is removed to prevent balloon rupture; and the one-valve is placed on the graft and secured with three 2-0 silk ties. Under fluoroscopic guidance, the Glidewire is then inserted through the needle into the graft and then through the SCA into the aorta.
Occasionally, the wire will pass directly into the descending aorta. On other occasions, the wire heads preferentially into the ascending aorta. The following techniques can be useful in redirecting the catheter:
- placing a right coronary artery Amplatz catheter (AGA Medical Corp, Plymouth, MN) in the ascending aorta and working the catheter leftwards and upwards, toward the arch;
- using an omni-flush catheter (reverse angle catheter) and nonstiff glide wire, and once the wire is pointed in the appropriate direction, switching out the omni-flush for a glide catheter or quick-cross catheter; and directing the wire into the descending aorta;
- if a Type 1 or 2 arch is present and access is from the right, using a directional hydrophilic (e.g., angled Glidewire) and simple curved catheter (e.g., Kumpe or Bernstein), advancing the catheter into the arch and directing the catheter down the arch;
- if a Type 3 arch is present and access is from the right, advancing a complex curved catheter (e.g., Simmons 1) down the ascending aorta then pulling back so as to engage the tip on the greater curve; and
- as a last resort, placing the catheter in the LV, then using the inferior wall to support the catheter—a stiff wire can be inserted upwards back through the aortic valve into the ascending aorta. The wire then typically goes into the arch and then the descending aorta.
Next, the balloon is placed over the wire to a point 2 cm below the left SCA. The distal end should be placed just distal to the left subclavian. This can typically be confirmed by both transesophageal echocardiography and fluoroscopy. The wound over the Gore-Tex graft is closed in layers. Therefore, the only foreign material that traverses the skin is the balloon catheter, which does so through a separate puncture site below the incision.
Left SCA access is theoretically more desirable because it is a more direct route to the descending aorta and it avoids the need to traverse the arch vessels. However, in patients with a coronary artery bypass using the left internal mammary artery, a left-sided automatic internal cardiac defibrillator, a biventricular pacer, or catheters, we preferentially use the right SCA. When possible, in BTR patients, we opt to place the SCA-IABP before cardiopulmonary bypass (CPB) to facilitate weaning CPB at the termination of the case and to avoid bleeding related to full heparinization.
The SCA-IABP can be placed in advance of surgery, in an effort to optimize the patient before cardiac surgery, and remain in place for postoperative recovery. For example, one of our patients suffered a non-ST elevation myocardial infarction; the patient was loaded with clopidogrel and was catheterized at an outside hospital. The cardiac catheterization revealed severe multivessel disease, severely diminished left ventricular function, severe mitral regurgitation, and a large left ventricular aneurysm. Given the antiplatelet therapy and evolving infarction, the timing was not optimal for cardiac surgery. Therefore, the patient was taken to the operating room for SCA-IABP placement. The patient then recovered in the intensive care unit for 5 days, providing time for the antiplatelet therapy to take effect. During this time, the patient was able to ambulate and undergo physical therapy, while on SCA-IABP support. On hospital day 6, the patient underwent concomitant coronary artery bypass grafting (CABG) x 5, mitral valve replacement, left ventricular aneurysm resection, and atrial septal defect closure. The postoperative course was uneventful. The patient was extubated on the day of the procedure and ambulated on postoperative day 1. The SCA-IABP was removed on postoperative day 5, and the patient was ultimately discharged on postoperative day 11.
Conversely, for patients in cardiogenic shock, SCA-IABP insertion typically requires too much time to be placed before CPB. Therefore, we recommend placing a femoral IABP perioperatively and returning to the operating room (OR) on the following day, or when the patient is sufficiently stable, to convert the patient to a SCA-IABP. For example, one of our patients suffered a perforation of the second diagonal branch. Subsequently, a femoral IABP was placed in the catheterization lab in preparation for surgery. The patient was taken emergently to the OR where the patient was placed on CPB, underwent a CABG x 2, repair of the perforated diagonal, and atrial valve replacement. This patient returned to the OR on postoperative day 2 for placement of a SCA-IABP and removal of the femoral IABP.
In our experience, the femoral IABP should be left in place while the SCA-IABP is placed. When wire access is obtained, the femoral IABP can be turned off to allow for placement of the subclavian balloon and the femoral balloon can be removed or exchanged for a femoral sheath, which can be removed at a later time. To exchange the IABP for a sheath, the IABP typically must be cut at the end. Then, a 0.025” wire (for 7.5 or 8 F) or a 0.018” wire (for 7 F) must be threaded through the IABP. The sheath is then placed over the wire. If a femoral IABP was placed through a sheath, it is often difficult exchange it over a wire, and the sheath and IABP need to be pulled together.
Patient characteristics are described in Table 1. The mean age of the cohort was 69.7 ± 9.9 years and the mean Society of Thoracic Surgeons score was 24.0 ± 26.3. Preoperative diagnoses included coronary artery disease/ischemic cardiomyopathy (n = 11), ventricular septal defect (VSD; n = 1), mitral valve regurgitation (n = 6), left ventricular aneurysm (n = 2), and aortic valve dysfunction (n = 3). The balloon was inserted via the right SCA in eight (72.7%) patients and the left SCA in three (27.3%) patients. The procedures performed included CABG only (n = 2); mitral valve surgery (MVS) + CABG (n = 3); MVS + CABG + left ventricular aneurysm resection (n = 2); MVS + VSD closure (n = 1); and aortic valve replacement + CABG (n = 3; Table 2).
Patient outcomes are summarized in Table 3. There were no device-related complications or in-hospital mortalities. Mean time to ambulation, duration of balloon pump support, and postoperative length of stay were 3.7 ± 2.5, 8.5 ± 7.0, and 15.9 ± 8.3 days, respectively. Two patients had deep vein thrombosis of the internal jugular vein—one was ipsilateral to the IABP and one contralateral. Four patients had prolonged ventilation (>48 hours). One patient was later readmitted for a deep sternal wound infection and subsequently discharged after treatment.
In a previous study, our group described favorable outcomes using SCA-IABPs as a bridge to transplant in end-stage heart failure patients awaiting heart transplantation.5 Based on these experiences, we hypothesized that SCA-IABPs may benefit patients undergoing valve or CABG surgery with severe obstructive coronary artery disease that cannot be fully revascularized, as well as patients with recent myocardial infarctions, VSDs, and/or mitral valve regurgitation who have low left ventricular ejective fractions.5 In this early experience with SCA-IABPs as a BTR in high-risk cardiac surgery patients, there were no in-hospital mortalities or device-related complications. No major vascular complications, device-related infections, strokes, or episodes of bleeding requiring reoperation were observed. There were, however, two patients with deep vein thrombosis of the internal jugular vein and four patients who had prolonged ventilation (>48 hours).
Current options for heart failure patients waiting to undergo complex cardiac procedures include IABP or Impella 2.5 (Abiomed, Danvers, MA) device placement. The PROTECT II trial, which randomized 452 symptomatic patients to IABP (n = 226) or Impella 2.5 (n = 226) support during nonemergent high-risk percutaneous coronary intervention, found no significant difference in outcome, despite a strong trend toward decreased major adverse events in the Impella arm of the trial.8 Other case series describe favorable outcomes using the Impella 2.5 in more severely ill cardiac surgery patients.9 Despite these favorable reports using the Impella device, it is important to underline that IABPs have a number of attractive characteristics: they are effective, relatively low cost, associated with low morbidity, and available in most countries around the world where interventional cardiology has become standardized.
There are, however, limitations to IABPs, which are largely related to the difficulties of femoral access. First, groin catheters prevent ambulation. In fact, the patient is not allowed to flex the femur more than 20°, which usually prevents the patient from sitting upright. Second, despite the widespread use, and initial promise,10,11 of sheathless insertions of IABPs, limb-related complications still occur in 3%–36% of cases.10,12,13 These complications are partially due to balloon perforations on plaque and partially due to the combination of vasoactive agents and balloon placement in the femoral artery. The femoral artery may have fewer collaterals than the SCA meaning balloon placement significantly increases the risk of ischemia to the limb. Finally, femoral catheters may be associated with higher infection rates. Such concerns serve as a deterrent for IABP placement in many patients.8,9
Subclavian artery insertion of the IABP overcomes many of these limitations. The SCA is generally free of atherosclerosis. Therefore, SCA access can be used in patients with severe peripheral vascular disease of the lower extremities. Furthermore, there are no special restrictions for positioning the patient, which not only allows the patient to be more comfortable but also allows the patient to ambulate and participate in physical therapy. Moreover, SCA access may help avoid the deleterious effects of vasoactive agents, including limb ischemia and acute kidney injury, and the effects of inotropic agents, including arrhythmias and hypotension. Finally, the use of the one-way valve, previously described by our group,5 allows safe removal or exchange at the bedside, without vascular compromise to the arm.
Despite the common use of intraaortic balloon pumps to support cardiac surgery patients, the prophylactic use of IABPs remains controversial. In a multicenter propensity analysis, Lorusso et al.14 showed that prophylactic IABP enhanced perioperative outcomes of high-risk cardiac surgery patients. Similarly, Field et al.15 concluded in a meta-analysis of preoperative intraaortic balloon pumps in patients undergoing CABG that IABPs may have a beneficial effect on postoperative outcomes.
Conversely, the SHOCK II trial found no benefit with IABP in 600 patients who had acute myocardial infarction complicated by cardiogenic shock.16 However, the SHOCK II trial primarily enrolled patients undergoing percutaneous coronary intervention, instead of patients undergoing CABG (<5%). Furthermore, the study has been criticized due to significant crossover between groups: 4.3% of the patients assigned to the IABP died before having the IABP placed, and 10% of the control group underwent IABP placement. Another recent study by Ranucci et al.17 found no difference between patients with IABP undergoing high-risk CABG and those undergoing the same procedure with no IABP, in terms of postoperative major morbidity rate (prolonged mechanical ventilation, stroke, acute kidney injury, surgical revision, mediastinitis, and operative mortality). However, the Ranucci study showed a trend toward lower mortality in the IABP group (7.3% vs. 14%). Therefore, based on available data, the prophylactic use of IABP support, particularly via the SCA, needs further evaluation.
The limitations of our study include all the caveats of a small, nonrandomized, retrospective case series, and additional follow-up and experience is needed. Ideally, the safety of SCA-IABPs would be tested in the setting of a randomized trial against femoral IABPs. However, given the impracticality and cost of conducting randomized trials, and given the generally positive outcomes we report, this data is among the best existing evidence, until further studies can be conducted, validating the use of SCA-IABPs.
Prophylactic SCA-IABPs appear to be safe in high-risk cardiac surgery patients as a BTR. In our cohort of 11 patients, we report no device-related complications or in-hospital mortalities. Initial experience warrants further application and investigation of this approach.
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