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Ann Thorac Surg 2009;88:1462-1466. doi:10.1016/j.athoracsur.2009.07.015
© 2009 The Society of Thoracic Surgeons
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Original Articles: Adult Cardiac

Role of a Percutaneous Ventricular Assist Device in Decision Making for a Cardiac Transplant Program

William T. Brinkman, MDa,b,*, Jed E. Rosenthal, MDa, Eric Eichhorn, MDa,b, Todd M. Dewey, MDa,b, Mitchell J. Magee, MDa,b, Darinka S. Savor, RNa, Angela G. Riley, RTa,b, Syma L. Prince, RNb, Christine M. Worley, RNb, Morley A. Herbert, PhDa, Michael J. Mack, MDa,b

a Medical City Dallas Hospital, Dallas, Texas
b Cardiopulmonary Research Science and Technology Institute, Dallas, Texas

Accepted for publication July 10, 2009.

* Address correspondence to Dr Brinkman, Medical City Dallas Hospital, 7777 Forest Ln, Ste A-323, Dallas, TX 75230 (Email: wbrinkman{at}csant.com).

Presented at the Poster Session of the Forty-fifth Annual Meeting of The Society of Thoracic Surgeons, San Francisco, CA, Jan 26–28, 2009.


   Abstract
Top
 Abstract
Introduction
 Material and Methods
 Results
 Comment
 References
 
Background: The role of a percutaneous ventricular assist device (VAD) for left heart support in the management of patients in cardiogenic shock is not well defined.

Methods: All patients who received LV support using the percutaneous TandemHeart (percTH) ventricular support device (Cardiac Assist, Pittsburgh, PA) were retrospectively reviewed. Indications for insertion included bridge to decision (BTD) or "salvage" and bridge to transplant (BTT).

Results: Between April 2005 and December 2008, 22 percTH devices were successfully implanted in patients (13 men) with isolated left heart failure. Mean duration of support was 6.8 ± 9.4 days (median, 4; maximum, 45 days). Of patients requiring percTH support for at least 3 days, mean pump flows were 3.77 ± 1.10, 4.22 ± 0.69, and 4.04 ± 0.41 L/min on at days 1, 2, and 3. Mean serum aspartate aminotransferase levels were 455 ± 994 mg/dL before percTH, 551 ± 1046 mg/dL at day 1, and 231 ± 225 mg/dL at day 3 after percTH. No mechanical device failure, device-related infections, or cerebrovascular accidents occurred. Ten of 11 BTT patients were successfully bridged. Support was withdrawn in 7 of 11 BTD patients. The percTHs were successfully explanted in 4 BTD patients: 1 as recovery, 1 direct to transplant, and 2 to VAD.

Conclusions: The percTH was reliable, with no mechanical device failures and minimal associated adverse events. We support the use of the percTH in the BTD mode, allowing time for a more complete evaluation of neurologic and end-organ status without the added expense and morbidity of a long-term VAD.


   Introduction
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 Abstract
 Introduction
Material and Methods
 Results
 Comment
 References
 
Mechanical circulatory support continues to have an ever-expanding role in the management of congestive heart failure. Improvements in patient survival and quality of life have been demonstrated with the use of long-term left ventricular assist devices (LVADs) in selected patients [1]. Frequently, however, decisions about institution of mechanical circulatory support are made with patients in a moribund state; for example, long-term mechanical support or transplantation may not be appropriate in a patient with questionable neurologic status or multisystem organ failure [2]. Moreover, because fully implantable VADs and cardiac transplantation require the use of cardiopulmonary bypass, their implementation can be complex and use immense resources in the setting of severe heart failure.

Until recently, the only percutaneous options for mechanical cardiac support were intraaortic balloon pumps (IABPs) or extracorporeal membrane oxygenators (ECMOs). Both systems are easily inserted and less expensive than LVADs, but the actual mechanical support provided to the heart is modest, which limits their effectiveness for cardiac support. Percutaneously inserted temporary LVADs have recently been introduced for short-term cardiac support. This has allowed expanded options for the management of acute and acute-on-chronic heart failure [3, 4].

For the moribund patient classified as bridge to decision (BTD) or salvage, we have used the percutaneous mechanical support provided by the TandemHeart (percTH; Cardiac Assist, Pittsburg, PA). We believe that the percutaneous institution of mechanical circulatory support in a BTD setting permits heart failure treatment to be initiated more rapidly, thus allowing for better allocation of resources, such as surgically implanted VADs and donor hearts for transplant. Moreover, no sternotomy is required, which facilitates subsequent transplantation or surgically implanted VAD insertion.

Here we report our experience with the percTH in a cohort of patients with end-stage heart failure in whom pharmacologic support measures were not successful. The percTH is a single-use extracorporeal centrifugal blood pump that uses a very low prime volume (10 mL) and is driven by a 3-phase, brushless, DC servomotor capable of delivering up to 5.0 L/min of blood flow. Instead of using conventional mechanical roller bearings, this design features a hydrodynamic fluid bearing that supports the spinning rotor [5].

This mechanical support was initiated in a BTD or salvage mode in patients with questionable neurologic status or multisystem organ failure (MSOF), or both. In another group of patients that we have reviewed after using the percTH, the mechanical support was initiated in a bridge to transplant (BTT) mode. These patients were thought to be candidates for VAD or transplant but required the interim device for stabilization of their condition or while arrangements or funding were being made for a VAD.


   Material and Methods
Top
 Abstract
 Introduction
 Material and Methods
Results
 Comment
 References
 
After approval from the North Texas Institutional Review Board at Medical City, a review was performed of all patients placed on LV support using a percTH. Indications included BTD/salvage and BTT. Patients defined as BTD presented in a moribund state, and their overall clinical viability was in question owing to possible severe neurologic injury or MSOF. Patients defined as BTT were judged to be candidates for elective transplantation or recovery if their cardiac failure could be stabilized by short-term percutaneous mechanical support.

The percTHs were inserted in an urgent or emergency setting in patients with INTERMACS profile levels 1 (critical cardiogenic shock) or 2 (deteriorating on inotropes) in accordance with the 2007 International Registry for Mechanically Assisted Circulatory Support report [6]. Technical success was defined as percutaneous placement of the percTH with proper cannula placement and adequate pump flows.

All conscious patients provided informed consent. If the patient was unable to consent, the medical team acted in the patient's best interest after informed consent from the next of kin and consultation with the Ethics Committee. All patient management decisions were made by the on-call cardiac transplant surgeon in consultation with the cardiologist.

The insertion technique and performance characteristics of the percTH have been described previously [7]. Briefly, once decision for mechanical ventricular support was made, the patient was taken to the cardiac catheterization laboratory as an emergency. Standard cardiac fluoroscopy and transesophageal echocardiography imaging were used for guidance. A 6F Mullen sheath was positioned at the intraatrial septum. An angled guide needle was inserted into the left atrium, followed by a super stiff Amplatz wire (AGA Medical Corp, Plymouth, MN). With the stiff wire (Med-Tech, Miami, FL) positioned in the left atrium, two dilators were passed into the left atrium. The 21F percTH transseptal cannula was then positioned in the left atrium and the Amplatz wire removed. After adequate inflow access, percTH outflow access was obtained through the common femoral artery.

Intraoperative angiography was used for side selection for arterial cannula insertion. Standard Seldinger technique was used to insert the arterial cannulas (size range, 15F to 17F). If the common femoral artery was too small for the appropriate arterial cannula, then an 8-mm side graft was sewn on the common femoral artery in an end-to-side fashion. Bilateral femoral artery cannulation was also an option, but was not used in these patients.


   Results
Top
 Abstract
 Introduction
 Material and Methods
 Results
Comment
 References
 
Between April 2005 and August 2008, percTH implantation was successful in 22 patients, comprising 13 men (59%). Patients were a mean age of 48 ± 14 years, and all had isolated LV failure. All devices were placed percutaneously, and technical success was achieved in the group. Two technical failures occurred. We were not able to achieve transseptal access in a patient who had undergone after orthotopic heart transplantation 1 year before, and the second patient sustained an immediate hemopericardium during transseptal catheter insertion and required mediastinal exploration.

LV failure in the BTD group included ischemic cardiomyopathy in 3 patients, idiopathic cardiomyopathy in 3, viral cardiomyopathy in 1, refractory ventricular fibrillation in 1, and acute myocardial infarction in 3. Causes in the BTT group were similar, with ischemic cardiomyopathy in 4, idiopathic cardiomyopathy in 4, viral cardiomyopathy in 1, and acute myocardial infarction in 2. In 11 patients the percTH was placed as a BTD or salvage, and the other 11 were a BTT group. Tables 1 and 2 Go summarize patient characteristics and outcomes.


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  		Table 1 Characteristics and Outcomes of Patients in the Salvage Group
 

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  		Table 2 Characteristics and Outcomes of Patients in the Bridge Group
 
Mean duration of support was 6.8 ± 9.4 days (median, 4; maximum, 45 days). Mean pump flows were 3.77 ± 1.10, 4.22 ± 0.69, and 4.04 ± 0.41 L/min on postinsertion days 1, 2, and 3, respectively. The mean serum aspartate aminotransferase levels were 455 ± 994 mg/dL before implant and 551 ± 1046 mg/dL on day 1 and 231 ± 225 mg/dL on day 3 after insertion (Fig 1).


Figure 1
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  		Fig 1. Changes in mean aspartate aminotransferase (AST; large dashes), alanine aminotransferase (ALT, gray line), bilirubin (gray dashes), and creatinine (small dashes) concentrations during use of TandemHeart device. Creatinine readings from patients on dialysis were excluded from calculations.

 
Of the 11 patients assigned to BTT, 8 received an allograft or underwent long-term VAD insertion, and 2 recovered cardiac function and their units were removed after a mean of 10 ± 1 days on the device. One patient died of Nocardia endocarditis and gram-negative sepsis (Fig 2) Of the 11 patients assigned to BTD or salvage because of neurologic injury, MSOF, or were not deemed an acceptable LVAD or transplant candidate at that time, 4 were salvaged and were successfully weaned from the percTH. Two patients ultimately received an allograft, 1 patient recovered cardiac function and the percTH was explanted, and 1 other patient recovered sufficiently to have the percTH unit explanted and replaced by a long-term LVAD; unfortunately, the patient died while on the LVAD. Overall, 3 of the 11 patients are currently alive (Fig 2).


Figure 2
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  		Fig 2. Diagram shows initial patient distribution and outcomes in the (A) bridge group and the (B) salvage group. (LVAD = left ventricular assist device.)

 
There were no instances of mechanical device failure. Prolonged use of the device (exceeding 7 days) occurred in 7 patients. Bleeding complications in 3 patients were related to a profound coagulopathy in 1, a right atrial laceration during insertion in 1, and groin cannulation site hemorrhage in 1. All patients were kept immobilized in an intensive care unit setting while the percTH was in use. Groin complications included 2 lower extremity compartment syndromes requiring fasciotomies and femoral artery endarterectomy to reestablish distal perfusion after cannula removal. Heparin-induced thrombocytopenia occurred in 1 patient. No percTH-related infections or cerebrovascular accidents were noted.

Analysis of catheter laboratory data showed an average time required for insertion of the percTH was 62 ± 24 minutes from the start of the first catheter placement until the pump was started, a further 18 ± 12 minutes until the end of the case.


   Comment
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
References
 
Patient selection for LVAD placement traditionally has involved two major factors: (1) appropriateness for device implant according to patient symptoms and overall condition; and (2) the risk of VAD implantation [8]. This process is further complicated in an acute-on-chronic exacerbation of congestive heart failure or acute heart failure with questionable viability such as neurologic injury or MSOF, or both. It is in this situation of the acute-on-chronic and fulminate acute congestive heart failure with questionable viability that we have used the precTH. We believe that the expeditious implementation of percutaneous ventricular support expands the clinician's options while minimizing expense in materials and personnel. The percutaneous nature of the device also avoids sternotomy and cardiac manipulation, which can complicate subsequent transplantation or placement of a surgically implanted VAD.

Other centers have reported on the use of ECMO in similar situations. The technologies are quite similar; however, we believe that in the adult population with isolated LV failure the percTH is superior to ECMO for several reasons:

• The left atrium is decompressed in the TH circuit, unlike the traditional ECMO setup. This is an important point if there is a possibility of cardiac recovery.
• Activated clotting times and heparin levels may be run at lower levels without the membrane oxygenator in the circuit.
• If oxygenation is an issue, the percTH circuit can be easily converted to ECMO at the bedside with the addition of an oxygenator.

Other options for percutaneous ventricular support include catheter-based axial flow pumps. We, however, have not incorporated this technology into our practice currently.

The beneficial use of the percTH is well illustrated by the clinical course of a 37-year-old man who was transferred to our center after an emergency redo aortic valve replacement for prosthetic valve endocarditis. Upon arrival, he was in cardiogenic shock with an intraaortic balloon pump in place. He had sustained a ventricular fibrillatory arrest during the transfer and required 45 minutes of cardiopulmonary resuscitation. His neurologic status was in question upon arrival. He therefore was taken immediately to the catheterization laboratory where a percTH was placed in a BTD or salvage mode. After 1 day of percTH support with adequate flows, his neurologic status normalized. He continued to have repeated bouts of ventricular fibrillation and received multiple cardioversions. Because of his continued ventricular ectopy, a long-term implantable VAD, a HeartMate XVE (Thoratec, Pleasanton, CA), was inserted in a BTT mode. The patient eventually received an orthotopic heart transplant and is doing well currently.

Very few device-related complications occurred in this single-center review, and most were primarily related to bleeding and groin access issues. There were no mechanical device failures even with use of up to 45 days. Most importantly, there were no device-related strokes and no significant infectious complications. Patients must remain supine in bed while the percTH is implanted, which does limit its long-term application. Careful attention must be maintained to transseptal cannula position at all times. Significant right-to-left shunting can result when the transseptal cannula is pulled back into the right atrium.

Our data support the assertion that the percTH provided meaningful physiologic support, with pump flows averaging 3.74 ± 0.90 L/min while it was being used. In addition, elevated levels of serum creatinine and liver enzymes dropped to acceptable values.

Although the transseptal puncture can be technically challenging, we have found that the combination of fluoroscopy and transesophageal echocardiography greatly facilitates transseptal cannula placement. In fact, we only had one transseptal puncture failure, which occurred in the setting of a prior orthotopic heart transplant. Device placement was performed in a salvage mode in a patient who arrived with MSOF and uncertain neurologic status. This patient was allowed to die in the catheterization laboratory after our technical failure.

Only one early death occurred in the 11 patients deemed BTT. This patient had Nocardia endocarditis, sepsis, and MSOF. Of the 10 patients whose percTH was explanted, 5 immediately received a transplant, 3 underwent surgically implanted VAD placement, 2 of whom went on to receive a transplants; and 2 patients recovered and the percTH units were removed. Thus, the percTH was a successful bridge in more than 90% of the BTT patients. In the 11 patients deemed salvage or BTD who were technical successes, support was withdrawn in 7 and they died. One of the 4 survivors in this group recovered, 1 received a transplant, and 2 underwent surgical VAD placement, of whom 1 patient later received a transplant.

In conclusion, our data back the use of the percTH for short-term cardiac support in isolated LV failure an effort to facilitate BTT therapy in the clinically unstable patient. The value of this approach allows the quick implementation of cardiac support without complicating subsequent transplantation or surgical VAD insertion. The percTH device was reliable, with no mechanical device failures and minimal associated adverse events.

Our experience also supports the use of the perTH in the BTD or salvage mode. Although most of these patients did not survive and their long-term viability was uncertain at the primary evaluation, they were by no means futile situations, as illustrated by the recovery of 4 patients that allowed explant of the percTH device. The percTH, we believe, allowed time for a more complete evaluation of neurologic and end-organ status before proceeding to long-term VAD or transplantation.


   References
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 References
 

  1. Rose E, Gelijns A, Moskowitz A, et al. Long-term use of left ventricular assist device for end stage heart failure N Engl J Med 2001;345:1435-1443.[Medline]
  2. Miller L, Lietz K. Candidate selection for long term left ventricular assist device therapy for refractory heart failure J Heart Lung Transplant 2006;25:756.[Medline]
  3. 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.[Medline]
  4. Pitsis AA, Visouli AN, Burkhoff D, et al. Feasibility study of a temporary percutaneous left ventricular assist device in cardiac surgery Ann Thorac Surg 2007;84:1993-1999.[Abstract/Free Full Text]
  5. Cardiac Assist I. TandemHeart System Pump. http://www.cardiacassist.com/tandemheart/pump.asp 2008.
  6. International Registry for Mechanically Assisted Circulatory Support (INTERMACS)http://www.intermacs.org/membership.aspx 2008.
  7. Kar B, Adkins L, Civitello A, et al. Clinical Experience with the TandemHeart Percutaneous Ventricular Assist Device Tex Heart Inst J 2006;33:111-115.[Medline]
  8. Aaronson K, Patel H, Pagani F. Patient selection for left ventricular assist device therapy Ann Thorac Surg 2003;75:S29-S35.[Abstract/Free Full Text]

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