Impella-Assisted Balloon Aortic Valvuloplasty for Critical Aortic Stenosis as a Bridge to Transcatheter Aortic Valve Replacement

The pathophysiology of aortic stenosis (AS) involves progressive narrowing of the aortic valve (AV) orifice. Contributing inflammatory factors to the development of AS include mechanical stress-induced endothelial damage, lipid oxidation leading to fibrosis, and calcification.¹ The resultant high-outflow resistance creates a large pressure gradient across the AV, increasing afterload and further augmenting left ventricular hypertrophy. Decompensated patients will consequently develop the classic symptoms of angina, syncope, and dyspnea.¹

Aortic stenosis and mitral valvular regurgitation are the most common form of valvular dysfunction in developed nations. The prevalence of AS increases exponentially with age, affecting approximately 3% of patients over 65.² Untreated, symptomatic AS can be rapidly fatal, with an annual morality of 25% and an average survival rate of only 2-3 years.³ Time-sensitive transcatheter aortic valve replacement (TAVR) can be curative and offers an improved quality of life for high-risk patients with AS that are unsuitable for surgical aortic valve replacement (SAVR). Specifically, improvement in valve hemodynamics and symptom reduction has been demonstrated in patients with severe AS who underwent TAVR.⁴

TAVR does not come without risks, especially in patients with concurrent extracardiac comorbidities. One of the most feared complications of TAVR in such patients is cardiogenic shock. Balloon aortic valvuloplasty (BAV) is a percutaneous procedure that introduces micro-fractures to disintegrate calcified AV deposits via balloon inflation. In so doing, enhanced leaflet compliance leads to a rise in ejection fraction and improved hemodynamics in preparation for TAVR.⁵ Complementary BAV in inoperable patients may serve as a means for palliation and act as bridge to future successful prosthetic valve implantation.

Patients with diminished LV function may also require auxiliary intraoperative hemodynamic support during BAV to mitigate the increased risk of hypotension, tachycardia, and hemodynamic compromise. Over the past decade, newly designed percutaneous ventricular assist devices (pVAD) have become commercially available for the purpose of providing periprocedural circulatory support.⁶ Impella (Abiomed), a micro-axial continuous pVAD, is one such device that has been increasingly used for cardiogenic stability.⁶ However, the Impella system is considered a relative contraindication in patients with severe AS/calcification with an equivalent orifice area of less than 0.6 cm². Nonetheless, the advent of improved technology, higher-level skill sets, and advanced training have allowed interventional cardiologists to achieve successful Impella use in severe AS, thereby challenging this contraindication. In light of this information, we are presenting two critical AS cases in which BAV was conducted with Impella support as a bridge to TAVR.

Case Presentations

Case 1: The patient is a 69-year-old male who was referred to the cardiology service for symptoms of heart failure, including progressively worsening shortness of breath and lower extremity edema. His past medical history is significant for diabetes mellitus type 2, chronic kidney disease, dyslipidemia, and recently diagnosed severe AS. At the time of visit, he was a 90 pack-year smoker and heavy alcohol user. Physical examination findings revealed a systolic ejection murmur at the right second intercostal space, an absent S2, profound ascites, and lower extremity edema. A dobutamine stress echocardiogram was performed and showed critical AS (AV area of 0.99 cm²) with biventricular failure and suspected pulmonary hypertension. His LV was dilated with a diminished ejection fraction of <15%. He was subsequently diagnosed with acute on chronic systolic heart failure (New York Heart Association [NYHA] Functional Capacity IV, Stage C) and later was admitted to the hospital. It was determined that he had a 1-year mortality risk of >50%. Considering his dismal prognosis, he was subsequently scheduled for heart catheterization with potential BAV to further evaluate cardiac parameters and the extent of disease. Cardiac catheterization revealed a left ventricular ejection fraction (LVEF) <15%, an AV area of 0.82 cm², and a mean AV pressure gradient of 23 mmHg and a peak-peak gradient of 30 mmHg. There was an 80% occlusion of the proximal left circumflex artery and 100% occlusion of the mid-right coronary artery with good collaterals. Additionally, elevated intracardiac filling pressures with a reduced cardiac index of 1.92 L/min/m² was found. Catheterization also confirmed the presence of moderate to severe pulmonary hypertension with a mean pulmonary arterial pressure of 45 mmHg and a mean pulmonary capillary wedge pressure of 25 mmHg. The patient was deemed a high-risk candidate for surgical intervention and subsequently underwent BAV followed by a staged percutaneous coronary intervention (PCI) of the circumflex artery in order to improve the EF. Successful BAV with a 22 mm NuCLEUS balloon (B. Braun Interventional Systems) through a right femoral cutaneous approach was performed under Impella 2.5 utilization for cardioprotection (Figures 1-2). An Impella was placed through a left femoral arterial approach at a flow rate of 2 L/min and remained in the left ventricle for approximately 2 hours. An improved peak-peak gradient of 15 mmHg post BAV was noted. Hemodynamic parameters are described in Table 1. At the end of the procedure, the Impella was withdrawn, and both right and left femoral sites were pre-closed with the previously placed two Perclose (Abbott Vascular) sutures. After five months of significant clinical improvement, successful TAVR with a 29 mm Sapien 3 valve (Edwards Lifesciences) via a left femoral cutaneous approach was performed, with a repeat BAV due to the massive calcification of the AV. The prosthetic valve was deployed while pacing at 180 beats/minute. Post-implant hemodynamic parameters included an EF of 15% and a peak velocity of 2.87 cm/s, with a mean AV gradient of 13.7 mmHg. The patient tolerated the procedure well and had significant clinical improvement.

Case 2: The patient is a 94-year-old male who was admitted for symptoms of congestive heart failure exacerbation with NYHA Functional Capacity 4 status and concurrent asymptomatic non-ST elevation myocardial ischemia. Echocardiogram with Doppler revealed normal LVEF, severe AS with peak velocity >4 m/s, and an aortic valve area of 0.79 cm². Cardiac catheterization revealed 50% occlusion of the left main coronary artery, 70% occlusion of the mid-left anterior descending (LAD) artery, 90% stenosis of the distal circumflex, a mildly diseased right coronary artery, and a severely diseased distal LAD and right posterior descending artery. It was determined that the patient would be a high-risk candidate for surgical intervention given his morbid state. He has a past medical history of AS, diabetes mellitus type 2 with neuropathy, hypertension, and hyperlipidemia. He denied smoking; however, admitted to occasional alcohol use. On physical exam, the patient had a III/VI late peaking, a systolic ejection murmur, and bilateral ankle edema. Right femoral access was accomplished and BAV with staged PCI was performed under protection of a 2.5 Impella due to high-risk valvuloplasty and profound LAD disease. The Impella was inserted through the left femoral artery and was advanced with mild difficulty across the AV. Cardiac output was maintained at 2.5 L/min during BAV for approximately 40 minutes with the use of Impella. After the valvuloplasty, the patient remained hemodynamically stable, and the Impella was slowly weaned off and removed. Severe AS was treated with BAV using a 20 mm NuCLEUS balloon as a conduit to future TAVR (Figures 1-2). Following the procedure, mean gradient decreased from 48 to 27 mmHg and the aortic valve area increased from 0.6 to 1.4 cm². Hemodynamic parameters are described in Table 1. Mid LAD, distal LAD, and circumflex lesions were stented with a complex intervention involving rotational atherectomy and drug-eluting stent placement. The patient showed significant clinical improvement and was admitted for a TAVR two months later. Successful TAVR using a Sapien 3 valve with repeat BAV was performed through a left femoral percutaneous approach. A periprocedural transthoracic echocardiogram demonstrated correct positioning and an expanded prosthetic valve with normal leaflet mobility. Post-implant peak velocity was found to be 1.4 m² with a mean systolic gradient of 4.5 mmHg. Post-operative EF was found to be 60%.

Discussion and Conclusion

As the population continues to age, the prevalence of AS among patients with a grave surgical outcome is expected to proportionally increase. For decades, SAVR has been the gold standard for definitive treatment of severe AS; however, the invasive nature of the operation is inclined to increase mortality and complications. A recent observational nationwide study by Lemor et al⁷ compared TAVR and SAVR in octo- and nonagenerians. The article concluded that TAVR is an efficient and safe substitute for SAVR with lower in-hospital mortality, fewer major in-hospital complications, and a lower 30-day readmission rate.⁷ The PARTNER I trial, a study that compared the death rates among patients undergoing either TAVR or SAVR, showed a similar 30-day mortality between groups; however, TAVR demonstrated an improvement in quality of life and symptom reduction.⁸

Patients with significant comorbidities present a challenge in performing successful TAVR. To alleviate associated complications, the use of BAV has resurfaced as a conduit to TAVR. Originally, BAV was focused on nonsurgical symptom management of severe AS in critically ill patients. Soon after the emergence of BAV, its use received criticism for a high restenosis rate and in-hospital mortality.⁵ Blood transfusion and vascular injury were among the most common complication for patients who underwent BAV, occurring at rates of 23% and 7%, respectively.⁹ Despite the known complications associated with BAV, advancements in technology and cardiovascular training have improved its efficacy and safety.

The contemporary era of invasive cardiology has revisited the use of BAV as a bridge to future TAVR. BAV has been consequently shown to reduce hemodynamic compromise and re-hospitalizations, and provide temporary symptomatic relief in patients anticipating transcutaneous prosthetic valve placement.¹⁰ Specifically, Singh et al reported an increased one-year survival rate in patients who underwent BAV as a transition to definitive therapy when compared to BAV use as a means of palliation.¹¹ Additionally, in particularly frail patients, adjunct BAV can aid in predicting post-TAVR prognosis and prevent fruitless operations.¹² Furthermore, BAV can be used intraoperatively to facilitate the delivery of the transcatheter aortic valve in the setting of massive AV calcification.

Interdependent pVAD use with BAV provides additional cardiac stabilization during balloon inflation, thereby minimizing BAV-associated hemodynamic impediments. Hemodynamic discrepancies can be especially cumbersome for elderly patients with concomitant coronary artery disease. pVAD use has become increasingly attractive due to its synergistic effect in improving BAV efficiency by adequately unloading the LV, thus increasing cardiac output. The resultant decrease in wall tension promotes enhanced cardiac contractility, increased coronary perfusion, and reduced myocardial oxygen demand. Although inotropic agents can be used for cardiovascular stability, these agents can simultaneously give rise to myocardial ischemia and can cause ventricular arrhythmias. Additionally, inotropic medications’ efficacy in improving mortality has not been demonstrated in studies.¹³

The Impella catheter is a commonly used pVAD that is advanced percutaneously through the femoral artery, and retrogradely implanted into the LV, traversing the diseased AV. The Impella system achieves hemodynamic support by drawing blood from the LV and pumping it into the ascending aorta. The advancement of the Impella device through the critically stenosed AV may potentially damage and diminish the remaining valve function, and further compromise hemodynamic stability. It is for this reason that the original use of Impella is considered as a contraindication in patients with severe AS. However, in recent years there have been several articles that have demonstrated the efficacy, feasibility, and safety of Impella use in patients with a. severely stenosed AV orifice.^14-18

The PROTECT II trial, a comprehensive, prospective, randomized clinical trial, studied the use of Impella in high-risk PCI with LV failure (LVEF ≤35%). The results of the trial proved the superiority of Impella in providing hemodynamic support over an intra-aortic balloon pump (IABP). Furthermore, Impella support during PCI demonstrated decreased major adverse events at 90-day follow-up.¹⁹ TandemHeart (LivaNova) is an alternate pVAD that can be used for patients with tenuous cardiac parameters and has similar hemodynamic capability when compared to Impella. However, TandemHeart is not readily available in many institutions and requires highly experienced clinicians for its sophisticated insertion. Due to the more invasive placement and larger cannula size, TandemHeart also increases the risk of damage to adjacent cardiovascular structures; leading to possible cardiac tamponade, excessive bleeding and higher ischemic complications.^20-21

The patients presented in this case report were deemed too high risk for surgical intervention, including coronary artery bypass graft (CABG) surgery and SAVR. Concomitant comorbidities within these patients consisted of severe AS, complex coronary artery disease, diminished LV reserve, and various extra-cardiac risk factors. Both patients showed troublesome activities of daily life due to the associated symptoms of AV stenosis, which necessitated a mechanical solution. It was determined that future TAVR could be a potential long-term solution. However, temporary improvement of symptoms and functional status dictated the usage of BAV with staged PCI as a bridge to TAVR. Specifically, BAV allows for the improvement of LVEF, and PCI increases coronary perfusion, collectively decreasing myocardial oxygen demand. As a result of poor post-procedural survival rates, patients required additional intra-operative hemodynamic stability during BAV via the utilization of Impella. Successful forward flow during BAV was achieved using the Impella system and both patients tolerated the procedure well without any complications. Thereafter, definitive treatment with TAVR was accomplished with an enhanced overall quality of life. In conclusion, we propose that BAV with Impella support is an effective and safe procedure as a bridge to future TAVR. 

¹College of Osteopathic Medicine, Marian University, Indianapolis, Indiana; ²Community Hospital North, Heart and Vascular, Indianapolis, Indiana

Disclosures: The authors report no conflicts of interest regarding the content herein.

The authors can be contacted via Sandeep Dube, MD, FACC, FSCAI, Director of Cardiac Catheterization Labs, Community Heart and Vascular Hospital, Indianapolis, Indiana, at sdube@ecommunity.com.

1. Dweck MR, Boon NA, Newby DE. Calcific aortic stenosis: a disease of the valve and the myocardium. J Am Coll Cardiol. 2012 Nov 6; 60(19): 1854-1863.
2. Lindman BR, Clavel MA, Mathieu P, et al. Calcific aortic stenosis. Nat Rev Dis Primers. 2016 Mar 3; 2: 16006.
3. Bates ER. Treatment options in severe aortic stenosis. Circulation. 2011; 124(3): 355-359.
4. Makkar RR, Fontana GP, Jilaihawi H, et al. Transcatheter aortic-valve replacement for inoperable severe aortic stenosis. N Engl J Med. 2012; 366(18): 1696-1704.
5. Hara H, Pedersen WR, Ladich E, et al. Percutaneous balloon aortic valvuloplasty revisited: time for a renaissance? Circulation. 2007; 115(12): e334-e338.
6. Martinez CA, Singh V, Londoño JC, et al. Percutaneous retrograde left ventricular assist support for interventions in patients with aortic stenosis and left ventricular dysfunction. Catheter Cardiovasc Interv. 2012; 80(7): 1201-1209.
7. Lemor A, Villablanca P, Hernandez G, et al. Comparison of outcomes of transcatheter versus surgical aortic valve replacement in patients ≥80 years of age. Am J Cardiol. 2019 Jun 1; 123(11): 1853-1858.
8. Leon MB, Smith CR, Mack M, et al; PARTNER Trial Investigators. Transcatheter aortic-valve implantation for aortic stenosis in patients who cannot undergo surgery. N Engl J Med. 2010; 363(17): 1597-1607.
9. Percutaneous balloon aortic valvuloplasty. Acute and 30-day follow-up results in 674 patients from the NHLBI Balloon Valvuloplasty Registry. Circulation. 1991 Dec; 84(6): 2383-2397.
10. Kumar A, Paniagua D, Hira RS, et al. Balloon aortic valvuloplasty in the transcatheter aortic valve replacement era. J Invasive Cardiol. 2016 Aug; 28(8): 341-348.
11. Singh V, Yadav PK2, Eng MH, et al. Outcomes of hemodynamic support with Impella in very high-risk patients undergoing balloon aortic valvuloplasty: Results from the Global cVAD Registry. Int J Cardiol. 2017; 240: 120-125.
12. Saia F, Moretti C, Dall’Ara G, et al. Balloon aortic valvuloplasty as a bridge-to-decision in high risk patients with aortic stenosis: a new paradigm for the heart team decision making. J Geriatr Cardiol. 2016; 13(6): 475-482
13. Khan MH, Corbett BJ, Hollenberg SM. Mechanical circulatory support in acute cardiogenic shock. F1000Prime Rep. 2014 Oct; 6: 91.
14. Londono J, Martinez C, Singh V, O’Neill W. Hemodynamic support with Impella 2.5 during balloon aortic valvuloplasty in a high-risk patient. J Interv Cardiol. 2011; 24: 193-197.
15. Spiro J, Venugopal V, Raja Y, Ludman PF, Townend JN, Doshi SN. Feasibility and efficacy of the 2.5 L and 3.8 L Impella percutaneous left ventricular support device during high-risk, percutaneous coronary intervention in patients with severe aortic stenosis. Catheter Cardiovasc Interv. 2015 May; 85(6): 981-989.
16. Martinez CA, Singh V, Londoño JC, et al. Percutaneous retrograde left ventricular assist support for interventions in patients with aortic stenosis and left ventricular dysfunction. Catheter Cardiovasc Interv. 2012; 80(7): 1201-1209.
17. Waggoner, TE, George JC. Percutaneous left ventricular device supported aortic balloon valvuloplasty and simultaneous complex percutaneous coronary intervention. Cath Lab Digest. 2017 May; 25(5): 40-41.
18. Singh V, Yadav PK, Eng MH, et al. Outcomes of hemodynamic support with Impella in very high-risk patients undergoing balloon aortic valvuloplasty: results from the Global cVAD Registry. Int J Cardiol. 2017; 240: 120-125.
19. O’Neill WW, Kleiman NS, Moses J, et al. A prospective, randomized clinical trial of hemodynamic support with Impella 2.5 versus intra-aortic balloon pump in patients undergoing high-risk percutaneous coronary intervention: the PROTECT II study. Circulation. 2012; 126(14): 1717-1727.
20. Ergle K, Parto P, Krim SR. Percutaneous ventricular assist devices: a novel approach in the management of patients with acute cardiogenic shock. Ochsner J. 2016 Fall; 16(3): 243-249.
21. Gilotra NA, Stevens GR. Temporary mechanical circulatory support: a review of the options, indications, and outcomes. Clin Med Insights Cardiol. 2015 Feb 3; 8(Suppl 1): 75-85.