REVIEW URRENT C OPINION
Short-term continuous-flow ventricular assist devices Hiroo Takayama a, Koji Takeda a, Darshan Doshi b, and Ulrich P. Jorde b
Purpose of review To provide a comprehensive update on the current state of short-term, continuous-flow ventricular assist devices (CF-VADs) in the treatment of refractory cardiogenic shock in Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) 1 patients. Recent findings The mortality rate associated with refractory cardiogenic shock remains markedly elevated, with INTERMACS 1 profile repeatedly demonstrating the worst outcomes. Recent innovations in continuous-flow pump technology have not only contributed to improved outcomes with long-term left ventricular assist device technology, but have also led to the development of various short-term, percutaneous, and surgical CF-VADs. Short-term CF-VADs have several favorable features, but, most notably, they allow the effective temporary stabilization of otherwise refractory cardiogenic shock and serve as a bridge-to-decision therapy. Summary Clinical evidence supporting the use of CF-VADs still remains at the level of small case series, but the data appear promising. However, further rigorous clinical investigation is necessary in order to prove the overall clinical efficacy of these devices in refractory cardiogenic shock. Keywords cardiogenic shock, CentriMag, Impella, short-term VAD, TandemHeart
INTRODUCTION Nearly 15 years after the seminal SHould we emergently revascularize Occluded Coronaries for cardiogenic shock (SHOCK) trial established the benefits of early revascularization in cardiogenic shock [1], the overall in-hospital mortality rate for cardiogenic shock because of acute myocardial infarction (AMI) remains nearly unchanged at 50% and approaches nearly 100% in patients with the worst hemodynamics [2–4]. Furthermore, the recent Intraaortic balloon counterpulsation in AMI complicated by cardiogenic shock: design and rationale of the Intraaortic Balloon Pump in Cardiogenic Shock II (IABP-SHOCK II) trial suggested that the only routinely employed form of mechanical circulatory support (MCS), the intra-aortic balloon pump (IABP), confers no benefit in AMI and cardiogenic shock [5 ]. Clearly, more powerful MCS is needed in order to improve the outcomes [6]. The progress of MCS is highlighted by the implementation of implantable continuous-flow left ventricular assist device (LVAD) therapy in the management of patients with advanced chronic heart &
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failure. As the technology associated with continuous-flow LVADs continues to evolve, it may eventually contribute to the care of patients in the earlier, more acute stages of heart failure. However, at present, the use of devices designed to support long-term chronic heart failure in acutely decompensating patients does not appear promising [7]. Some of the characteristics of an implantable LVAD, such as inability to simultaneously assist the right ventricle (RV), the need for a complex surgical implant procedure, and high cost, make it an unfavorable device of choice for cardiogenic shock.
a
Division of Cardiothoracic Surgery and bDivision of Cardiology, New York Presbyterian Hospital, Columbia University Medical Center, New York, New York, USA Correspondence to Ulrich P. Jorde, MD, Medical Director, MCSD Programs, New York Presbyterian Hospital, Columbia University Medical Center, 622 West 168th Street, PH9-977, New York, NY 10032, USA. Tel: +1 212 305 0167; fax: +1 212 305 7139; e-mail: upj1@columbia. edu Curr Opin Cardiol 2014, 29:266–274 DOI:10.1097/HCO.0000000000000060 Volume 29 Number 3 May 2014
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AV, aortic valve; AxA, axillary artery; FA, femoral artery; IABP, intra-aortic balloon pump; LA, left atrium; LV, left ventricle; pVAD, percutaneous ventricular assist device; RA, right atrium; RV, right ventricle; VA-ECMO, venoarterial extracorporeal membrane oxygenation.
LV distension High High Yes Yes No 15–30 Easy Inflow: 19–25 Fr in RA; outflow: 15–23 Fr in FA VA-ECMO
3–6
NA
No Very high
NA Yes
No Yes
No Maybe
Yes 120
NA Less difficult
Surgery Any surgical cannula in any cardiac chamber CentriMag surgical VAD
5 14 Fr sheath in FA Reitan pVAD
10
Relatively low Relatively low Maybe Near future Yes 15–30 Less difficult 12–21 Fr pump across AV, 11 Fr catheter in FA or AxA Impella pVAD
2.5–5
Low Low
High Yes
Yes No
Yes Maybe
Maybe 10
30–60 Difficult
Easy 0.5
Inflow: 21 Fr in LA; Outflow: 15–17 Fr in FA
3–4
7–9 Fr in descending aorta
Bed rest RV support LV unload Insertion time (min) Insertion technique Flow (l/min) Size, location
Currently available pVADs include the TandemHeart system (CardiacAssist Inc., Pittsburgh, Pennsylvania, USA) and the Impella system (Abiomed Inc., Pittsburgh, Pennsylvania, USA) (Table 1). Other pVADs under active investigation include the Reitan catheter pump (CardioBridge GmbH; Hechingen, Germany) and the Percutaneous Heart Pump (Thoratec, Pleasanton, California, USA). These pVADs are an appealing and promising therapeutic approach for cardiogenic shock, and have become increasingly popular. They can be inserted quickly, are less invasive for unstable patients, and may decrease morbidity compared with surgical VADs. However, in a meta-analysis of three randomized studies comparing pVAD (two studies with TandemHeart and one study with Impella 2.5) with IABP, pVAD did not improve 30-day mortality (relative risk 1.06, 95% confidence interval 0.68–1.66) [13].
Table 1. Characteristics of short-term mechanical circulatory support devices
PERCUTANEOUS SHORT-TERM VENTRICULAR ASSIST DEVICE
Bleeding risk
Multidisciplinary approach is essential in order to improve the overall care of cardiogenic shock with MCS.
TandemHeart pVAD
Rigorous clinical trials are needed to establish the role of short-term VADs in cardiogenic shock therapy.
IABP
Limb ischemia risk
Various short-term, percutaneous, and surgical CF-VADs are available and in development.
High
Other
Cardiogenic shock still continues to have high mortality.
Continuous-flow technology itself, however, has significantly advanced the use and popularity of MCS. In comparison with the first generation of short-term VADs, such as ABIOMED BVS5000, which was built on the basis of pulsatile flow pump technology, current generation short-term VADs consist exclusively of continuous-flow pumps. These pumps have improved durability, biocompatibility, and ease of maintenance. Furthermore, continuous-flow pump technology has allowed miniaturization of the actual pump body, which has been translated into some forms of percutaneous VADs (pVADs). Supported by these advancements, short-term VADs have become an accepted treatment option in cardiogenic shock [8–12]. The purpose of this review is to provide a comprehensive update on the current state of short-term continuous-flow ventricular assist devices (CF-VADs) as a treatment modality for patients in refractory cardiogenic shock.
Hemolysis
KEY POINTS
Surgical risks
Continuous-flow ventricular assist devices Takayama et al.
267
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Cardiac failure
This disappointing result may be a reflection of the limitations of studied pVADs, such as limited flow capacity, limited support period, need for bed rest, and need for an experienced interventionalist and cardiac catheterization laboratory. With the introduction of newer devices and technology, pVADs may eventually emerge as the standard of care in the immediate treatment of AMI and cardiogenic shock.
The TandemHeart percutaneous ventricular assist device The TandemHeart is an extracorporeal continuousflow pump that can generate up to 4 l/min of flow at 7500g. The LVAD system consists of a 21-Fr inflow cannula inserted from the femoral vein into the left atrium through a transseptal puncture, a 15-Fr or 17-Fr outflow cannula inserted into the femoral artery, and an extracorporeal pump (Fig. 1). A special cannula and an experienced pair of hands are necessary for the transseptal approach. Positioning the cannulas in the main pulmonary artery and the right atrium allows use of the device for a right VAD configuration. The hemodynamic effects of percutaneous LVAD support using the TandemHeart has been investigated by Thiele et al. [14] in 18 patients with cardiogenic shock because of myocardial infarction. Before support, cardiac index was 1.7 0.3 l/min/m2 Impella 2.5
and improved to 2.4 0.6 l/min/m2, and mean blood pressure increased from 63 8 to 80 9 mmHg (all P < 0.001). Pulmonary capillary wedge pressure, central venous pressure, and pulmonary artery pressure were reduced from 21 4, 13 4, and 31 8 to 14 4, 9 3, and 23 6 mmHg (all P < 0.001), respectively. In another study, patients with AMI and cardiogenic shock were randomized to either IABP (n ¼ 20) or TandemHeart LVAD (n ¼ 21) [15]. Cardiac power index, as well as other hemodynamic and metabolic variables, improved more substantially with TandemHeart LVAD support. However, complications, such as severe bleeding and limb ischemia, were more frequent with the pVAD. Thirty-day mortality was not significantly different (IABP 45% vs. pVAD 43%). More recently, Kar et al. [16] reported a total of 117 patients with cardiogenic shock supported with this device. Forty-eight percent (n ¼ 56) were undergoing active cardiopulmonary resuscitation immediately before or at the time of insertion. The average duration of support was 5.8 4.75 days. After implantation, a sizeable reduction of pulmonary capillary wedge pressure from 31.53 10.2 to 17.29 10.82 mm Hg was seen (P < 0.001), demonstrating the ability of the TandemHeart to adequately decompress the left ventricle (LV) from the left atrium. Additionally, the cardiac index, systolic blood pressure, mixed venous oxygen TandemHeart
FIGURE 1. Impella 2.5 and TandemHeart. The transvalvular, axial flow Impella 2.5 is shown on the left, whereas the left atrial-to-femoral artery centrifugal TandemHeart is shown on the right. Reproduced by courtesy of Abiomed, Inc. (for photograph of Impella 2.5) and CardiacAssist Inc. (CAI; for photograph of TandemHeart). 268
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Continuous-flow ventricular assist devices Takayama et al.
saturation, urine output, lactic acid level, and creatinine level all improved. The 30-day and 6-month mortality rates were 40.2% and 45.3%, respectively. However, widespread use seems to still be limited because of the technical complexity of a transseptal puncture in the emergent or urgent situation, as well as occasional dislodgement of the left atrial cannula back into the right atrium.
Impella left ventricular assist device system The Impella LVAD system is the clinical translation of miniaturized, rotary pump technology. The size of the pump starts as small as 12-Fr, which is amenable to total percutaneous insertion. A catheter-mounted continuous-flow axial pump is placed across the aortic valve with the inflow in the LV and the outflow in the ascending aorta under fluoroscopic and echocardiographic guidance (Fig. 1). The family of the Impella system includes 2.5 (12-Fr, 2.5 l/min of flow), Continuous Power (CP) (14-Fr, 3.5 l/min of flow), 5.0 (21-Fr, 5 l/min of flow), and Left Direct (LD) (21-Fr, 5 l/min of flow) as well as the Impella right ventricular assist device (RVAD) (23-Fr, 5 l/min of flow). These pumps are operated through an 11-Fr catheter. The Impella’s hemodynamic support results from its ability to augment active forward flow to increase net cardiac output, while simultaneously unloading the LV. With the outflow of the Impella device in the aortic root, it provides both an active flow and systemic pressure contribution leading to increased cardiac power output. The inflow of the device draws blood directly from the ventricle, resulting in reduced ventricular end-diastolic volume and pressure, which leads to a reduction of mechanical work, myocardial wall tension, and myocardial oxygen demand. As opposed to the TandemHeart system or venoarterial extracorporeal membrane oxygenation (VA-ECMO), in which a larger catheter is left placed in the femoral artery, the Impella system predisposes the patients to lower risk of limb ischemia. On the other hand, the internal pump of the Impella is susceptible to positional change, which requires frequent echocardiograms with positional adjustment. Additionally, higher shear stress because of higher operational speed of the impeller might cause damage to the blood components [17]. Contraindications for Impella placement include significant peripheral arterial disease (if device is to be placed percutaneously), at least moderate ( 30 min of on-going CPR Septic shock Predicted extremely short-term life expectancy due to comorbidities
No
Yes
Selection of bridge-to-decision device
No device support
Any of the following? • Unknown neurological status • Severe hemodynamical status • Severe hemodynamical instability • Severe coagulopathy
Yes
Percutaneous VA-ECMO
No
Exchange when longer-term support needed with certain destination
Surgical CentriMag BiVAD
Impella 2.5 LVAD for LV decompression
Destinations • Exchange to implantable VAD • Explant for myocardial recovery • Heart transplantation • Death
FIGURE 4. Algorithm for bridge-to-decision device therapy. CPR, cardiopulmonary resuscitation; LV, left ventricle; MCS, mechanical circulatory support; VA-ECMO, venoarterial extracorporeal membrane oxygenation. 272
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Continuous-flow ventricular assist devices Takayama et al.
with implantable LVAD technology, but also to the development of various short-term percutaneous CF-VADs (TandemHeart, Impella, and other investigational devices) and surgical CF-VADs (CentriMag). These devices have favorable features for the treatment of cardiogenic shock, as well as allowing bridge-to-decision therapy. More powerful and durable devices with tailored features for cardiogenic shock treatment are still in development. Clinical evidence for each device, as well as for overall MCS therapy as a treatment for cardiogenic shock, however, remains at the level of case reports. Equally important to the evolution of technology is the pursuit of rigorous clinical trials to quantify the contribution of device therapy to the treatment of cardiogenic shock. However, a multidisciplinary approach plays a pivotal role to streamline this complex and rapidly changing environment surrounding MCS therapy for cardiogenic shock. Acknowledgements None. Conflicts of interest U.P.J. has received consulting fees of less than $5000 annually each from Thoratec, HeartWare, and Jarvik. H.T., K.T., and D.D. have nothing to disclose.
REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest && of outstanding interest 1. Hochman JS, Sleeper LA, Godfrey E, et al. SHould we emergently revascularize Occluded Coronaries for cardiogenic shocK: an international randomized trial of emergency PTCA/CABG-trial design. The SHOCK Trial Study Group. Am Heart J 1999; 137:313–321. 2. Goldberg RJ, Spencer FA, Gore JM, et al. Thirty-year trends (1975 to 2005) in the magnitude of, management of, and hospital death rates associated with cardiogenic shock in patients with acute myocardial infarction: a populationbased perspective. Circulation 2009; 119:1211–1219. 3. Thiele H, Allam B, Chatellier G, et al. Shock in acute myocardial infarction: the Cape Horn for trials? Eur Heart J 2010; 31:1828–1835. 4. Jeger RV, Lowe AM, Buller CE, et al. Hemodynamic parameters are prognostically important in cardiogenic shock but similar following early revascularization or initial medical stabilization: a report from the SHOCK Trial. Chest 2007; 132:1794–1803. 5. Thiele H, Zeymer U, Neumann FJ, et al. Intraaortic balloon support for & myocardial infarction with cardiogenic shock. N Engl J Med 2012; 367: 1287–1296. This randomized study questioned what is the standard of care of IABP use in AMI and cardiogenic shock. Also importantly, the study showed persistently high mortality, similar to the original SHOCK trial, suggesting importance of implementation of mechanical circulatory support device. 6. O’Connor CM, Rogers JG. Evidence for overturning the guidelines in cardiogenic shock. N Engl J Med 2012; 367:1349–1350. 7. Boyle AJ, Ascheim DD, Russo MJ, et al. Clinical outcomes for continuous-flow left ventricular assist device patients stratified by preoperative INTERMACS classification. J Heart Lung Transplant 2011; 30:402–407. 8. John R, Long JW, Massey HT, et al. Outcomes of a multicenter trial of the Levitronix CentriMag ventricular assist system for short-term circulatory support. J Thorac Cardiovasc Surg 2011; 141:932–939.
9. Samuels LE, Holmes EC, Garwood P, Ferdinand F. Initial experience with the Abiomed AB5000 ventricular assist device system. Ann Thorac Surg 2005; 80:309–312. 10. Griffith BP, Anderson MB, Samuels LE, et al. The RECOVER I: a multicenter prospective study of Impella 5.0/LD for postcardiotomy circulatory support. J Thorac Cardiovasc Surg 2013; 145:548–554. 11. Koerner MM, Jahanyar J. Assist devices for circulatory support in therapy – refractory acute heart failure. Curr Opin Cardiol 2008; 23:399–406. 12. Worku B, Naka Y, Pak SW, et al. Predictors of mortality after short-term ventricular assist device placement. Ann Thorac Surg 2011; 92:1608–1612; discussion 1612–1613. 13. Cheng JM, den Uil CA, Hoeks SE, et al. Percutaneous left ventricular assist devices vs. intra-aortic balloon pump counterpulsation for treatment of cardiogenic shock: a meta-analysis of controlled trials. Eur Heart J 2009; 30:2102–2108. 14. Thiele H, Lauer B, Hambrecht R, et al. Reversal of cardiogenic shock by percutaneous left atrial-to-femoral arterial bypass assistance. Circulation 2001; 104:2917–2922. 15. Thiele H, Sick P, Boudriot E, et al. Randomized comparison of intra-aortic balloon support with a percutaneous left ventricular assist device in patients with revascularized acute myocardial infarction complicated by cardiogenic shock. Eur Heart J 2005; 26:1276–1283. 16. Kar B, Gregoric ID, Basra SS, et al. The percutaneous ventricular assist device in severe refractory cardiogenic shock. J Am Coll Cardiol 2011; 57:688–696. 17. Lauten A, Engstrom AE, Jung C, et al. Percutaneous left-ventricular support with the Impella-2.5-assist device in acute cardiogenic shock: results of the Impella-EUROSHOCK-registry. Circ Heart Fail 2013; 6:23– 30. 18. Seyfarth M, Sibbing D, Bauer I, et al. A randomized clinical trial to evaluate the safety and efficacy of a percutaneous left ventricular assist device versus intra-aortic balloon pumping for treatment of cardiogenic shock caused by myocardial infarction. J Am Coll Cardiol 2008; 52:1584–1588. 19. Lauten A, Engstrom AE, Jung C, et al. Response to letter regarding article, ‘percutaneous left-ventricular support with the impella-2.5-assist device in acute cardiogenic shock results of the Impella-EUROSHOCK registry’. Circ Heart Fail 2013; 6:e56. 20. Koeckert MS, Jorde UP, Naka Y, et al. Impella LP 2.5 for left ventricular unloading during venoarterial extracorporeal membrane oxygenation support. J Card Surg 2011; 26:666–668. 21. Naidu SS. Novel percutaneous cardiac assist devices: the science of and indications for hemodynamic support. Circulation 2011; 123:533–543. 22. LaRocca GM, Shimbo D, Rodriguez CJ, et al. The Impella Recover LP 5.0 left ventricular assist device: a bridge to coronary artery bypass grafting and cardiac transplantation. J Am Soc Echocardiogr 2006; 19:468 e5– 468 e7. 23. Samoukovic G, Rosu C, Giannetti N, Cecere R. The Impella LP 5.0 as a bridge to long-term circulatory support. Interact Cardiovasc Thorac Surg 2009; 8:682–683. 24. Andrade JG, Al-Saloos H, Jeewa A, et al. Facilitated cardiac recovery in fulminant myocarditis: pediatric use of the Impella LP 5.0 pump. J Heart Lung Transplant 2010; 29:96–97. 25. Lemaire A, Anderson MB, Lee LY, et al. The Impella device for acute mechanical circulatory support in patients in cardiogenic shock. Ann Thorac Surg 2014; 97:133–138. 26. Margey R, Chamakura S, Siddiqi S, et al. First experience with implantation of a percutaneous right ventricular impella right side percutaneous support device as a bridge to recovery in acute right ventricular infarction complicated by cardiogenic shock in the United States. Circ Cardiovasc Interv 2013; 6:e37–e38. 27. Smith EJ, Reitan O, Keeble T, et al. A first-in-man study of the Reitan catheter pump for circulatory support in patients undergoing high-risk percutaneous coronary intervention. Catheter Cardiovasc Interv 2009; 73:859–865. 28. Keeble T, Hullin SE, Ferrari R, et al. Interim analysis of the reitan catheter pump heart failure efficacy study: reitan catheter pump improves cardiovascular and renal function in acute decompensated heart failure. Paris, France: EuroPCR; 2013. 29. Takayama H, Chen JM, Jorde UP, Naka Y. Implantation technique of the CentriMag biventricular assist device allowing ambulatory rehabilitation. Interact Cardiovasc Thorac Surg 2011; 12:110–111. 30. Mueller JP, Kuenzli A, Reuthebuch O, et al. The CentriMag: a new optimized centrifugal blood pump with levitating impeller. Heart Surg Forum 2004; 7:E477–E480. 31. Aziz TA, Singh G, Popjes E, et al. Initial experience with CentriMag extracorporal membrane oxygenation for support of critically ill patients with refractory cardiogenic shock. J Heart Lung Transplant 2010; 29:66–71. 32. De Robertis F, Rogers P, Amrani M, et al. Bridge to decision using the Levitronix CentriMag short-term ventricular assist device. J Heart Lung Transplant 2008; 27:474–478. 33. Loforte A, Montalto A, Ranocchi F, et al. Levitronix CentriMag third-generation magnetically levitated continuous flow pump as bridge to solution. ASAIO J 2011; 57:247–253.
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273
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Cardiac failure 34. Mohite PN, Zych B, Popov AF, et al. CentriMag(R) short-term ventricular assist as a bridge to solution in patients with advanced heart failure: use beyond 30 days. Eur J Cardiothorac Surg 2013; 44:e310–e315. 35. Takayama H, Naka Y, Jorde UP, Stewart AS. Less invasive left ventricular assist device placement for difficult resternotomy. J Thorac Cardiovasc Surg 2010; 140:932–933. 36. Takayama H, Naka Y, Kodali SK, et al. A novel approach to percutaneous rightventricular mechanical support. Eur J Cardiothorac Surg 2012; 41:423–426. 37. Maat AP, van Thiel RJ, Dalinghaus M, Bogers AJ. Connecting the Centrimag Levitronix pump to Berlin Heart Excor cannulae; a new approach to bridge to bridge. J Heart Lung Transplant 2008; 27:112–115.
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38. Jaroszewski DE, Marranca MC, Pierce CN, et al. Successive circulatory support stages: a triple bridge to recovery from fulminant myocarditis. J Heart Lung Transplant 2009; 28:984–986. 39. Hirata Y, Charette K, Mosca RS, et al. Pediatric application of the Thoratec CentriMag BiVAD as a bridge to heart transplantation. J Thorac Cardiovasc Surg 2008; 136:1386–1387. 40. Takayama H, Truby L, Koekort M, et al. Clinical outcome of mechanical & circulatory support for refractory cardiogenic shock in the current era. J Heart Lung Transplant 2013; 32:106–111. This single-center case series provides an overview of the current status of device therapy for various settings of cardiogenic shock.
Volume 29 Number 3 May 2014
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Short-term continuous-flow ventricular assist devices Hiroo Takayama a, Koji Takeda a, Darshan Doshi b, and Ulrich P. Jorde b
Purpose of review To provide a comprehensive update on the current state of short-term, continuous-flow ventricular assist devices (CF-VADs) in the treatment of refractory cardiogenic shock in Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) 1 patients. Recent findings The mortality rate associated with refractory cardiogenic shock remains markedly elevated, with INTERMACS 1 profile repeatedly demonstrating the worst outcomes. Recent innovations in continuous-flow pump technology have not only contributed to improved outcomes with long-term left ventricular assist device technology, but have also led to the development of various short-term, percutaneous, and surgical CF-VADs. Short-term CF-VADs have several favorable features, but, most notably, they allow the effective temporary stabilization of otherwise refractory cardiogenic shock and serve as a bridge-to-decision therapy. Summary Clinical evidence supporting the use of CF-VADs still remains at the level of small case series, but the data appear promising. However, further rigorous clinical investigation is necessary in order to prove the overall clinical efficacy of these devices in refractory cardiogenic shock. Keywords cardiogenic shock, CentriMag, Impella, short-term VAD, TandemHeart
INTRODUCTION Nearly 15 years after the seminal SHould we emergently revascularize Occluded Coronaries for cardiogenic shock (SHOCK) trial established the benefits of early revascularization in cardiogenic shock [1], the overall in-hospital mortality rate for cardiogenic shock because of acute myocardial infarction (AMI) remains nearly unchanged at 50% and approaches nearly 100% in patients with the worst hemodynamics [2–4]. Furthermore, the recent Intraaortic balloon counterpulsation in AMI complicated by cardiogenic shock: design and rationale of the Intraaortic Balloon Pump in Cardiogenic Shock II (IABP-SHOCK II) trial suggested that the only routinely employed form of mechanical circulatory support (MCS), the intra-aortic balloon pump (IABP), confers no benefit in AMI and cardiogenic shock [5 ]. Clearly, more powerful MCS is needed in order to improve the outcomes [6]. The progress of MCS is highlighted by the implementation of implantable continuous-flow left ventricular assist device (LVAD) therapy in the management of patients with advanced chronic heart &
www.co-cardiology.com
failure. As the technology associated with continuous-flow LVADs continues to evolve, it may eventually contribute to the care of patients in the earlier, more acute stages of heart failure. However, at present, the use of devices designed to support long-term chronic heart failure in acutely decompensating patients does not appear promising [7]. Some of the characteristics of an implantable LVAD, such as inability to simultaneously assist the right ventricle (RV), the need for a complex surgical implant procedure, and high cost, make it an unfavorable device of choice for cardiogenic shock.
a
Division of Cardiothoracic Surgery and bDivision of Cardiology, New York Presbyterian Hospital, Columbia University Medical Center, New York, New York, USA Correspondence to Ulrich P. Jorde, MD, Medical Director, MCSD Programs, New York Presbyterian Hospital, Columbia University Medical Center, 622 West 168th Street, PH9-977, New York, NY 10032, USA. Tel: +1 212 305 0167; fax: +1 212 305 7139; e-mail: upj1@columbia. edu Curr Opin Cardiol 2014, 29:266–274 DOI:10.1097/HCO.0000000000000060 Volume 29 Number 3 May 2014
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
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AV, aortic valve; AxA, axillary artery; FA, femoral artery; IABP, intra-aortic balloon pump; LA, left atrium; LV, left ventricle; pVAD, percutaneous ventricular assist device; RA, right atrium; RV, right ventricle; VA-ECMO, venoarterial extracorporeal membrane oxygenation.
LV distension High High Yes Yes No 15–30 Easy Inflow: 19–25 Fr in RA; outflow: 15–23 Fr in FA VA-ECMO
3–6
NA
No Very high
NA Yes
No Yes
No Maybe
Yes 120
NA Less difficult
Surgery Any surgical cannula in any cardiac chamber CentriMag surgical VAD
5 14 Fr sheath in FA Reitan pVAD
10
Relatively low Relatively low Maybe Near future Yes 15–30 Less difficult 12–21 Fr pump across AV, 11 Fr catheter in FA or AxA Impella pVAD
2.5–5
Low Low
High Yes
Yes No
Yes Maybe
Maybe 10
30–60 Difficult
Easy 0.5
Inflow: 21 Fr in LA; Outflow: 15–17 Fr in FA
3–4
7–9 Fr in descending aorta
Bed rest RV support LV unload Insertion time (min) Insertion technique Flow (l/min) Size, location
Currently available pVADs include the TandemHeart system (CardiacAssist Inc., Pittsburgh, Pennsylvania, USA) and the Impella system (Abiomed Inc., Pittsburgh, Pennsylvania, USA) (Table 1). Other pVADs under active investigation include the Reitan catheter pump (CardioBridge GmbH; Hechingen, Germany) and the Percutaneous Heart Pump (Thoratec, Pleasanton, California, USA). These pVADs are an appealing and promising therapeutic approach for cardiogenic shock, and have become increasingly popular. They can be inserted quickly, are less invasive for unstable patients, and may decrease morbidity compared with surgical VADs. However, in a meta-analysis of three randomized studies comparing pVAD (two studies with TandemHeart and one study with Impella 2.5) with IABP, pVAD did not improve 30-day mortality (relative risk 1.06, 95% confidence interval 0.68–1.66) [13].
Table 1. Characteristics of short-term mechanical circulatory support devices
PERCUTANEOUS SHORT-TERM VENTRICULAR ASSIST DEVICE
Bleeding risk
Multidisciplinary approach is essential in order to improve the overall care of cardiogenic shock with MCS.
TandemHeart pVAD
Rigorous clinical trials are needed to establish the role of short-term VADs in cardiogenic shock therapy.
IABP
Limb ischemia risk
Various short-term, percutaneous, and surgical CF-VADs are available and in development.
High
Other
Cardiogenic shock still continues to have high mortality.
Continuous-flow technology itself, however, has significantly advanced the use and popularity of MCS. In comparison with the first generation of short-term VADs, such as ABIOMED BVS5000, which was built on the basis of pulsatile flow pump technology, current generation short-term VADs consist exclusively of continuous-flow pumps. These pumps have improved durability, biocompatibility, and ease of maintenance. Furthermore, continuous-flow pump technology has allowed miniaturization of the actual pump body, which has been translated into some forms of percutaneous VADs (pVADs). Supported by these advancements, short-term VADs have become an accepted treatment option in cardiogenic shock [8–12]. The purpose of this review is to provide a comprehensive update on the current state of short-term continuous-flow ventricular assist devices (CF-VADs) as a treatment modality for patients in refractory cardiogenic shock.
Hemolysis
KEY POINTS
Surgical risks
Continuous-flow ventricular assist devices Takayama et al.
267
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Cardiac failure
This disappointing result may be a reflection of the limitations of studied pVADs, such as limited flow capacity, limited support period, need for bed rest, and need for an experienced interventionalist and cardiac catheterization laboratory. With the introduction of newer devices and technology, pVADs may eventually emerge as the standard of care in the immediate treatment of AMI and cardiogenic shock.
The TandemHeart percutaneous ventricular assist device The TandemHeart is an extracorporeal continuousflow pump that can generate up to 4 l/min of flow at 7500g. The LVAD system consists of a 21-Fr inflow cannula inserted from the femoral vein into the left atrium through a transseptal puncture, a 15-Fr or 17-Fr outflow cannula inserted into the femoral artery, and an extracorporeal pump (Fig. 1). A special cannula and an experienced pair of hands are necessary for the transseptal approach. Positioning the cannulas in the main pulmonary artery and the right atrium allows use of the device for a right VAD configuration. The hemodynamic effects of percutaneous LVAD support using the TandemHeart has been investigated by Thiele et al. [14] in 18 patients with cardiogenic shock because of myocardial infarction. Before support, cardiac index was 1.7 0.3 l/min/m2 Impella 2.5
and improved to 2.4 0.6 l/min/m2, and mean blood pressure increased from 63 8 to 80 9 mmHg (all P < 0.001). Pulmonary capillary wedge pressure, central venous pressure, and pulmonary artery pressure were reduced from 21 4, 13 4, and 31 8 to 14 4, 9 3, and 23 6 mmHg (all P < 0.001), respectively. In another study, patients with AMI and cardiogenic shock were randomized to either IABP (n ¼ 20) or TandemHeart LVAD (n ¼ 21) [15]. Cardiac power index, as well as other hemodynamic and metabolic variables, improved more substantially with TandemHeart LVAD support. However, complications, such as severe bleeding and limb ischemia, were more frequent with the pVAD. Thirty-day mortality was not significantly different (IABP 45% vs. pVAD 43%). More recently, Kar et al. [16] reported a total of 117 patients with cardiogenic shock supported with this device. Forty-eight percent (n ¼ 56) were undergoing active cardiopulmonary resuscitation immediately before or at the time of insertion. The average duration of support was 5.8 4.75 days. After implantation, a sizeable reduction of pulmonary capillary wedge pressure from 31.53 10.2 to 17.29 10.82 mm Hg was seen (P < 0.001), demonstrating the ability of the TandemHeart to adequately decompress the left ventricle (LV) from the left atrium. Additionally, the cardiac index, systolic blood pressure, mixed venous oxygen TandemHeart
FIGURE 1. Impella 2.5 and TandemHeart. The transvalvular, axial flow Impella 2.5 is shown on the left, whereas the left atrial-to-femoral artery centrifugal TandemHeart is shown on the right. Reproduced by courtesy of Abiomed, Inc. (for photograph of Impella 2.5) and CardiacAssist Inc. (CAI; for photograph of TandemHeart). 268
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Continuous-flow ventricular assist devices Takayama et al.
saturation, urine output, lactic acid level, and creatinine level all improved. The 30-day and 6-month mortality rates were 40.2% and 45.3%, respectively. However, widespread use seems to still be limited because of the technical complexity of a transseptal puncture in the emergent or urgent situation, as well as occasional dislodgement of the left atrial cannula back into the right atrium.
Impella left ventricular assist device system The Impella LVAD system is the clinical translation of miniaturized, rotary pump technology. The size of the pump starts as small as 12-Fr, which is amenable to total percutaneous insertion. A catheter-mounted continuous-flow axial pump is placed across the aortic valve with the inflow in the LV and the outflow in the ascending aorta under fluoroscopic and echocardiographic guidance (Fig. 1). The family of the Impella system includes 2.5 (12-Fr, 2.5 l/min of flow), Continuous Power (CP) (14-Fr, 3.5 l/min of flow), 5.0 (21-Fr, 5 l/min of flow), and Left Direct (LD) (21-Fr, 5 l/min of flow) as well as the Impella right ventricular assist device (RVAD) (23-Fr, 5 l/min of flow). These pumps are operated through an 11-Fr catheter. The Impella’s hemodynamic support results from its ability to augment active forward flow to increase net cardiac output, while simultaneously unloading the LV. With the outflow of the Impella device in the aortic root, it provides both an active flow and systemic pressure contribution leading to increased cardiac power output. The inflow of the device draws blood directly from the ventricle, resulting in reduced ventricular end-diastolic volume and pressure, which leads to a reduction of mechanical work, myocardial wall tension, and myocardial oxygen demand. As opposed to the TandemHeart system or venoarterial extracorporeal membrane oxygenation (VA-ECMO), in which a larger catheter is left placed in the femoral artery, the Impella system predisposes the patients to lower risk of limb ischemia. On the other hand, the internal pump of the Impella is susceptible to positional change, which requires frequent echocardiograms with positional adjustment. Additionally, higher shear stress because of higher operational speed of the impeller might cause damage to the blood components [17]. Contraindications for Impella placement include significant peripheral arterial disease (if device is to be placed percutaneously), at least moderate ( 30 min of on-going CPR Septic shock Predicted extremely short-term life expectancy due to comorbidities
No
Yes
Selection of bridge-to-decision device
No device support
Any of the following? • Unknown neurological status • Severe hemodynamical status • Severe hemodynamical instability • Severe coagulopathy
Yes
Percutaneous VA-ECMO
No
Exchange when longer-term support needed with certain destination
Surgical CentriMag BiVAD
Impella 2.5 LVAD for LV decompression
Destinations • Exchange to implantable VAD • Explant for myocardial recovery • Heart transplantation • Death
FIGURE 4. Algorithm for bridge-to-decision device therapy. CPR, cardiopulmonary resuscitation; LV, left ventricle; MCS, mechanical circulatory support; VA-ECMO, venoarterial extracorporeal membrane oxygenation. 272
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with implantable LVAD technology, but also to the development of various short-term percutaneous CF-VADs (TandemHeart, Impella, and other investigational devices) and surgical CF-VADs (CentriMag). These devices have favorable features for the treatment of cardiogenic shock, as well as allowing bridge-to-decision therapy. More powerful and durable devices with tailored features for cardiogenic shock treatment are still in development. Clinical evidence for each device, as well as for overall MCS therapy as a treatment for cardiogenic shock, however, remains at the level of case reports. Equally important to the evolution of technology is the pursuit of rigorous clinical trials to quantify the contribution of device therapy to the treatment of cardiogenic shock. However, a multidisciplinary approach plays a pivotal role to streamline this complex and rapidly changing environment surrounding MCS therapy for cardiogenic shock. Acknowledgements None. Conflicts of interest U.P.J. has received consulting fees of less than $5000 annually each from Thoratec, HeartWare, and Jarvik. H.T., K.T., and D.D. have nothing to disclose.
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Cardiac failure 34. Mohite PN, Zych B, Popov AF, et al. CentriMag(R) short-term ventricular assist as a bridge to solution in patients with advanced heart failure: use beyond 30 days. Eur J Cardiothorac Surg 2013; 44:e310–e315. 35. Takayama H, Naka Y, Jorde UP, Stewart AS. Less invasive left ventricular assist device placement for difficult resternotomy. J Thorac Cardiovasc Surg 2010; 140:932–933. 36. Takayama H, Naka Y, Kodali SK, et al. A novel approach to percutaneous rightventricular mechanical support. Eur J Cardiothorac Surg 2012; 41:423–426. 37. Maat AP, van Thiel RJ, Dalinghaus M, Bogers AJ. Connecting the Centrimag Levitronix pump to Berlin Heart Excor cannulae; a new approach to bridge to bridge. J Heart Lung Transplant 2008; 27:112–115.
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38. Jaroszewski DE, Marranca MC, Pierce CN, et al. Successive circulatory support stages: a triple bridge to recovery from fulminant myocarditis. J Heart Lung Transplant 2009; 28:984–986. 39. Hirata Y, Charette K, Mosca RS, et al. Pediatric application of the Thoratec CentriMag BiVAD as a bridge to heart transplantation. J Thorac Cardiovasc Surg 2008; 136:1386–1387. 40. Takayama H, Truby L, Koekort M, et al. Clinical outcome of mechanical & circulatory support for refractory cardiogenic shock in the current era. J Heart Lung Transplant 2013; 32:106–111. This single-center case series provides an overview of the current status of device therapy for various settings of cardiogenic shock.
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