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Off-pump Replacement of the INCOR Implantable Axial-flow Pump
Off-pump Replacement of the INCOR Implantable Axial-flow Pump Kuniki Nakashima, MD,a Matthias E. W. Kirsch, MD, PhD,a Emmanuelle Vermes, MD,a Odile Rosanval, MD,b and Daniel Loisance, MDa Owing to the actual increase of mechanical circulatory support durations, total or partial replacement of ventricular assist devices (VADs) will most certainly have to be performed with increasing frequency. Herein we report the case of a patient in whom an INCOR (Berlin Heart AG, Berlin) implantable axial-flow pump was replaced without the use of cardiopulmonary bypass (CPB), underscoring some of the unique features provided by this system. J Heart Lung Transplant 2009;28:199 –201. Copyright © 2009 by the International Society for Heart and Lung Transplantation.
The development of permanent support known as “destination therapy” and prolonged waiting times for patients bridged to transplantation both contribute to the actual increase of mean durations of mechanical circulatory support. Longer support times obviously increase the hazards of device-related complications such as thromboembolism, infection and primary pump dysfunction.1 In some cases, adequate management of these complications requires the replacement of parts of the entire ventricular assist device (VAD). Device replacement can be extremely challenging owing to devicerelated adhesions, which expose to injury of vital mediastinal structures or of the VAD itself. Furthermore, patients on VAD support are at increased risk of peri- and post-operative bleeding due to device-related chronic activation of fibrinolytic and inflammatory pathways and anti-thrombotic treatment. Finally, low or negative pressures in unloaded heart chambers expose patients to the risk of air embolism during the procedure. To reduce these hazards and to provide adequate circulatory support during the period of pump interruption required for replacement, most groups perform pump replacement under cardiopulmonary bypass (CPB) with cardioplegic or fibrillatory arrest.1,2 We report the case of a patient in whom an INCOR left ventricular assist device (LVAD) was replaced without the use of CPB, underscoring some unique features
From the aService de Chirurgie Thoracique et Cardiovasculaire and b Service d’Anesthésie-Réanimation, AP-HP, Hôpital Henri Mondor, Créteil, France. Submitted May 14, 2008; revised August 21, 2008; accepted November 18, 2008. Reprint requests: Kuniki Nakashima, MD, Service de Chirurgie Thoracique et Cardiovasculaire, Hôpital Henri Mondor, 51 avenue du Maréchal de Lattre de Tassigny, 94000 Cédex Créteil, France. Telephone: 33-1-4981-21-72. Fax: 33-1-49-81-21-52. E-mail: [email protected] Copyright © 2009 by the International Society for Heart and Lung Transplantation. 1053-2498/09/$–see front matter. doi:10.1016/ j.healun.2008.11.904
provided by this system. LVAD implantation without CPB has been already reported,3 but this is the first report of device exchange without CPB. CASE REPORT In August 2003, a 59-year-old patient with end-stage left ventricular failure related to ischemic cardiomyopathy, already revascularized by percutaneous coronary intervention (left ventricular ejection fraction 20%, left ventricular end-diastolic diameter 60 mm), was implanted with the INCOR device as an alternative to heart transplantation.4 Implantation was performed under CPB using aortic cross-clamping and cardioplegic arrest. We followed the INCOR clinical manual with regard to implantation technique. The INCOR (Figure 1) is an implantable axial-flow pump designed to support the left ventricle. The impeller is suspended by magnetic bearings and rotates at a speed of 8,000 revolutions/min, thus enabling flow delivery of 5 liters/min against a pressure of 100 mm Hg. All cannulae are made of silicone with some parts being reinforced with plastic webbing. The outflow cannula is furnished with a polyester velour patch allowing de-airing with a needle. Each cannula is connected to the pump using quick-snap connectors, which are easy to attach and re-open. Re-opening requires only turning the claw to the unlocked position. Post-operative recovery was uneventful and the patient left the intensive care unit on Day 15 and was dismissed from the hospital on Day 41. Anti-thrombotic therapy consisted of warfarin to maintain the international normalized ratio at 3.5. Aspirin was given according to the results of in vitro platelet activation tests as reported previously.5 Because of repeated upper gastrointestinal bleeding related to Dieulafoy’s disease, this regimen was subsequently replaced by low-molecularweight heparin for anti-coagulation (enoxaparin, target anti-Xa activity between 0.8 to 1.0 IU/ml) and a combination of aspirin with clopidogrel for platelet inhibition. No further bleeding or thromboembolic events were noted since that time. 199
200
Nakashima et al.
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still alive and well nearly 5 years after the first implantation.
Figure 1. The left ventricular assist device Berlin Heart INCOR (photograph provided courtesy of Berlin Heart AG).
During the first year of implantation, we observed a progressive increase in the bearing power of the pump. After consultation with the engineers, this modification was related to progressive alteration of the pump’s magnetic field. Of note, this modification did not impede pump function, but it did prompt our decision to replace the pump. Thus, the patient was scheduled for re-operation in November 2004. The operation was performed through median sternotomy. Dissection was greatly facilitated by the silicone structure of the inflow and outflow cannulae, which allowed direct use of electrocautery at the contact point of each cannula without harm. Once the device was dissected free, the pump was stopped. Owing to their silicone structure, the inflow and outflow cannulae could be cross-clamped (Figure 2A). The native heart function was sustained by inotropic drugs. The pump could be replaced extremely rapidly owing to the snap connectors (Figure 3) and could be de-aired through the velour reinforced patch (Figure 2B). The new pump was then activated and the operation was finished in a standard fashion without excessive bleeding. The duration of device deactivation (from clamping to unclamping) was 14 minutes, and total operation time (skin to skin) was 3 hours 30 minutes. Post-operative recovery was very uneventful. The patient left the intensive care unit on Day 2 and was dismissed from the hospital on Day 15. Since this replacement, the patient has had no further complications and is
DISCUSSION Longer support times will inevitably increase the incidence of pump-related complications requiring, in some cases, partial or total replacement of internal components of implantable mechanical circulatory support devices.1 Thus, in case of primary pump dysfunction or thrombosis, the sole replacement of the pump (i.e., leaving the inflow and outflow cannulae in place) appears as an attractive option. Unfortunately, with most of the current commercially available devices, replacement of the sole pump is awkward because of the impossibility to clamp and easily disconnect the inflow and outflow cannulae from the pump, and the absence of a de-airing site at the pump outflow. Thus, replacement usually requires CPB to avoid blood loss and either cardioplegic or fibrillatory arrest to avoid air embolism. However, the use of CPB in such re-operative settings in patients under antithrombotic therapy exposes the patient to major periand post-operative bleeding complications.
Figure 2. Intra-operative view. (A) Cross-clamping of the inflow and outflow cannulae. (B) De-airing though the velour reinforced patch.
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arrest, avoided blood loss, and reduced the risk of air embolism while disconnecting the pump from the inflow cannula. Second, the snap connectors allowed easy disconnection even after prolonged implantation and rapid reconnection of the new pump. The rapidity of this procedure allowed us to rely on the sole native heart function sustained by drugs and circumvented the need for CPB. Furthermore, these connectors provide a degree of rotational freedom around the long axis of the pump, which allows adjusting the orientation of the pump relative to the cannula after reconnection. Finally, the reinforced velour patch situated immediately at the pump outflow allowed for easy de-airing without risk of bleeding at the puncture site. Total or partial replacement of VADs will most certainly need to be performed with increasing frequency in the future. This eventuality should be recognized in the design of future VADs. Among the currently available devices, the INCOR VAD has some unique features that provide distinctive advantages in this situation. REFERENCES
Figure 3. The snap connector: (A) opened and (B) closed.
In the present case, some unique features of the INCOR VAD greatly facilitated pump replacement, allowing the procedure to be performed without CPB. First, the silicone structure of the inflow and outflow cannulae allowed easy dissection with electrocautery. Furthermore, even after prolonged implantation, they retained their suppleness and were easy to clamp both at the inflow and outflow sites. This prevented backflow through the pump during the period of pump
1. Briks EJ, Tansley PD, Yacoub MH, et al. Incidence and clinical management of life-threatening left ventricular assist device failure. J Heart Lung Transplant 2004;23:964 –9. 2. Francesca SL, Smith R, Gregoric ID, et al. Replacement of a malfunctioning HeartMate II left ventricular assist device in a 14-year-old after a sudden fall. J Heart Lung Transplant 2006;25: 862– 4. 3. Gregoric ID, La Francesca S, Myers T, et al. A less invasive approach to axial flow pump insertion. J Heart Lung Transplant 2008;27:423– 6. 4. Hetzer R, Weng Y, Potapov EV, et al. First experiences with a novel magnetically suspended axial flow left ventricular assist device. Eur J Cardiothorac Surg 2004;25:964 –70. 5. Houel R, Mazoyer E, Boval B, et al. Platelet activation and aggregation profile in prolonged external ventricular support. J Thorac Cardiovasc Surg 2004;128:197–202.
The development of permanent support known as “destination therapy” and prolonged waiting times for patients bridged to transplantation both contribute to the actual increase of mean durations of mechanical circulatory support. Longer support times obviously increase the hazards of device-related complications such as thromboembolism, infection and primary pump dysfunction.1 In some cases, adequate management of these complications requires the replacement of parts of the entire ventricular assist device (VAD). Device replacement can be extremely challenging owing to devicerelated adhesions, which expose to injury of vital mediastinal structures or of the VAD itself. Furthermore, patients on VAD support are at increased risk of peri- and post-operative bleeding due to device-related chronic activation of fibrinolytic and inflammatory pathways and anti-thrombotic treatment. Finally, low or negative pressures in unloaded heart chambers expose patients to the risk of air embolism during the procedure. To reduce these hazards and to provide adequate circulatory support during the period of pump interruption required for replacement, most groups perform pump replacement under cardiopulmonary bypass (CPB) with cardioplegic or fibrillatory arrest.1,2 We report the case of a patient in whom an INCOR left ventricular assist device (LVAD) was replaced without the use of CPB, underscoring some unique features
From the aService de Chirurgie Thoracique et Cardiovasculaire and b Service d’Anesthésie-Réanimation, AP-HP, Hôpital Henri Mondor, Créteil, France. Submitted May 14, 2008; revised August 21, 2008; accepted November 18, 2008. Reprint requests: Kuniki Nakashima, MD, Service de Chirurgie Thoracique et Cardiovasculaire, Hôpital Henri Mondor, 51 avenue du Maréchal de Lattre de Tassigny, 94000 Cédex Créteil, France. Telephone: 33-1-4981-21-72. Fax: 33-1-49-81-21-52. E-mail: [email protected] Copyright © 2009 by the International Society for Heart and Lung Transplantation. 1053-2498/09/$–see front matter. doi:10.1016/ j.healun.2008.11.904
provided by this system. LVAD implantation without CPB has been already reported,3 but this is the first report of device exchange without CPB. CASE REPORT In August 2003, a 59-year-old patient with end-stage left ventricular failure related to ischemic cardiomyopathy, already revascularized by percutaneous coronary intervention (left ventricular ejection fraction 20%, left ventricular end-diastolic diameter 60 mm), was implanted with the INCOR device as an alternative to heart transplantation.4 Implantation was performed under CPB using aortic cross-clamping and cardioplegic arrest. We followed the INCOR clinical manual with regard to implantation technique. The INCOR (Figure 1) is an implantable axial-flow pump designed to support the left ventricle. The impeller is suspended by magnetic bearings and rotates at a speed of 8,000 revolutions/min, thus enabling flow delivery of 5 liters/min against a pressure of 100 mm Hg. All cannulae are made of silicone with some parts being reinforced with plastic webbing. The outflow cannula is furnished with a polyester velour patch allowing de-airing with a needle. Each cannula is connected to the pump using quick-snap connectors, which are easy to attach and re-open. Re-opening requires only turning the claw to the unlocked position. Post-operative recovery was uneventful and the patient left the intensive care unit on Day 15 and was dismissed from the hospital on Day 41. Anti-thrombotic therapy consisted of warfarin to maintain the international normalized ratio at 3.5. Aspirin was given according to the results of in vitro platelet activation tests as reported previously.5 Because of repeated upper gastrointestinal bleeding related to Dieulafoy’s disease, this regimen was subsequently replaced by low-molecularweight heparin for anti-coagulation (enoxaparin, target anti-Xa activity between 0.8 to 1.0 IU/ml) and a combination of aspirin with clopidogrel for platelet inhibition. No further bleeding or thromboembolic events were noted since that time. 199
200
Nakashima et al.
The Journal of Heart and Lung Transplantation February 2009
still alive and well nearly 5 years after the first implantation.
Figure 1. The left ventricular assist device Berlin Heart INCOR (photograph provided courtesy of Berlin Heart AG).
During the first year of implantation, we observed a progressive increase in the bearing power of the pump. After consultation with the engineers, this modification was related to progressive alteration of the pump’s magnetic field. Of note, this modification did not impede pump function, but it did prompt our decision to replace the pump. Thus, the patient was scheduled for re-operation in November 2004. The operation was performed through median sternotomy. Dissection was greatly facilitated by the silicone structure of the inflow and outflow cannulae, which allowed direct use of electrocautery at the contact point of each cannula without harm. Once the device was dissected free, the pump was stopped. Owing to their silicone structure, the inflow and outflow cannulae could be cross-clamped (Figure 2A). The native heart function was sustained by inotropic drugs. The pump could be replaced extremely rapidly owing to the snap connectors (Figure 3) and could be de-aired through the velour reinforced patch (Figure 2B). The new pump was then activated and the operation was finished in a standard fashion without excessive bleeding. The duration of device deactivation (from clamping to unclamping) was 14 minutes, and total operation time (skin to skin) was 3 hours 30 minutes. Post-operative recovery was very uneventful. The patient left the intensive care unit on Day 2 and was dismissed from the hospital on Day 15. Since this replacement, the patient has had no further complications and is
DISCUSSION Longer support times will inevitably increase the incidence of pump-related complications requiring, in some cases, partial or total replacement of internal components of implantable mechanical circulatory support devices.1 Thus, in case of primary pump dysfunction or thrombosis, the sole replacement of the pump (i.e., leaving the inflow and outflow cannulae in place) appears as an attractive option. Unfortunately, with most of the current commercially available devices, replacement of the sole pump is awkward because of the impossibility to clamp and easily disconnect the inflow and outflow cannulae from the pump, and the absence of a de-airing site at the pump outflow. Thus, replacement usually requires CPB to avoid blood loss and either cardioplegic or fibrillatory arrest to avoid air embolism. However, the use of CPB in such re-operative settings in patients under antithrombotic therapy exposes the patient to major periand post-operative bleeding complications.
Figure 2. Intra-operative view. (A) Cross-clamping of the inflow and outflow cannulae. (B) De-airing though the velour reinforced patch.
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arrest, avoided blood loss, and reduced the risk of air embolism while disconnecting the pump from the inflow cannula. Second, the snap connectors allowed easy disconnection even after prolonged implantation and rapid reconnection of the new pump. The rapidity of this procedure allowed us to rely on the sole native heart function sustained by drugs and circumvented the need for CPB. Furthermore, these connectors provide a degree of rotational freedom around the long axis of the pump, which allows adjusting the orientation of the pump relative to the cannula after reconnection. Finally, the reinforced velour patch situated immediately at the pump outflow allowed for easy de-airing without risk of bleeding at the puncture site. Total or partial replacement of VADs will most certainly need to be performed with increasing frequency in the future. This eventuality should be recognized in the design of future VADs. Among the currently available devices, the INCOR VAD has some unique features that provide distinctive advantages in this situation. REFERENCES
Figure 3. The snap connector: (A) opened and (B) closed.
In the present case, some unique features of the INCOR VAD greatly facilitated pump replacement, allowing the procedure to be performed without CPB. First, the silicone structure of the inflow and outflow cannulae allowed easy dissection with electrocautery. Furthermore, even after prolonged implantation, they retained their suppleness and were easy to clamp both at the inflow and outflow sites. This prevented backflow through the pump during the period of pump
1. Briks EJ, Tansley PD, Yacoub MH, et al. Incidence and clinical management of life-threatening left ventricular assist device failure. J Heart Lung Transplant 2004;23:964 –9. 2. Francesca SL, Smith R, Gregoric ID, et al. Replacement of a malfunctioning HeartMate II left ventricular assist device in a 14-year-old after a sudden fall. J Heart Lung Transplant 2006;25: 862– 4. 3. Gregoric ID, La Francesca S, Myers T, et al. A less invasive approach to axial flow pump insertion. J Heart Lung Transplant 2008;27:423– 6. 4. Hetzer R, Weng Y, Potapov EV, et al. First experiences with a novel magnetically suspended axial flow left ventricular assist device. Eur J Cardiothorac Surg 2004;25:964 –70. 5. Houel R, Mazoyer E, Boval B, et al. Platelet activation and aggregation profile in prolonged external ventricular support. J Thorac Cardiovasc Surg 2004;128:197–202.