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Ann Thorac Surg 2003;76:2112-2114
© 2003 The Society of Thoracic Surgeons
a Department of Cardiothoracic and Vascular Surgery, Deutsches Herzzentrum Berlin, Berlin, Germany
Accepted for publication March 28, 2003.
* Address reprint requests to Dr Potapov, Deutsches Herzzentrum Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
e-mail: potapov{at}dhzb.de
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Abstract |
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Introduction |
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In patients with organ recovery without myocardial recovery a long-term MCS is necessary as a bridge to transplantation or as a permanent support [1, 2]. Usually, establishing long-term support in these patients involves repeat sternotomy and use of cardiopulmonary bypass (CPB) for the exchange of the cannulas, with consequently increased risk for bleeding and infection. In addition the use of two different systems leads to extensive costs. We report a new approach whereby the pumps from the Abiomed BVS 5000 (Abiomed, Danvers, MA) short-term assist device are combined with cannulas from the BerlinHeart (BerlinHeart AG, Berlin, Germany) long-term assist device as a first step. If the patient is a suitable candidate for long-term MCS, in the second step exchange of the Abiomed pumps for a BerlinHeart pump was performed in the intensive care unit without repeated sternotomy and use of CPB.
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Technique |
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If only left ventricular support is established, measures to minimize the risk of right ventricular heart failure are initiated, following the standard management. These measures consist of use of NO, restrictive fluid replacement, and restrictive catecholamine use to maintain cardiac output at a level not higher than that necessary for adequate organ perfusion [4]. Anticoagulation therapy with heparin was started 6 hours after cessation of bleeding and the anticoagulation management was performed in accordance with our institutional protocol [5]. To assess the myocardial recovery, echocardiographic studies were performed daily and MCS weaning was performed by reduction of the flow by 0.5 L every 30 minutes until 2 L/min was achieved. The hemodynamic situation was considered stable if under minimal inotropic drug support no increase or only a slight increase of wedge and central venous pressures and no decrease of perfusion pressure or cardiac output occurred.
If during the first 2 weeks of support the weaning attempts were unsuccessful, it was evaluated whether the patient was a candidate for long-term assist device support. The evaluation took into consideration age, neurologic status, signs of systemic infection, organ function, and social situation. If the patient was a suitable candidate for long-term MCS, pump exchange was performed on the intensive care unit. The BerlinHeart pump was primed with sterile saline solution and connected to the drive console. A heparin bolus of 5,000 IE was administered intravenously before pump stop. During the procedure the patient was slightly sedated with a short-acting hypnoticum. After disinfection of the skin and cannulas the Abiomed assist device was stopped, the left-side inflow and outflow cannulas clamped, and the connectors and the Abiomed pump removed from the BerlinHeart cannulas. In the next step the BerlinHeart pump was connected to the cannulas, the clamps removed, and the BerlinHeart assist device started. In patients with biventricular support the same procedure was performed for the right side.
The pump exchange for each side takes approximately 2 to 3 minutes. If necessary, catecholamines were given intravenously as a bolus to maintain stable arterial pressure and cardiac output. In patients with biventricular support the frequency of the counterpump was slowed during the exchange procedure. After the pump exchange the patients were mobilized and weaned from the respirator.
A 28-year-old woman was admitted under cardiopulmonary resuscitation that had lasted for 2 hours for intractable ventricular arrhythmia caused by acute myocarditis. She presented with wide, fixed pupils and no central reflexes were detected. After a short period of stabilization (with QRS complexes >0.8 s) ventricular fibrillation developed. Cardiopulmonary resuscitation was again initiated and she was transferred to the operating room where biventricular support was established as described. The patient regained consciousness without any neurologic deficits and the switch to a BerlinHeart pump was performed on the third postoperative day; she was extubated on the next day. Unfortunately after discharge she suffered from intracerebral bleeding and died on the 37th postoperative day.
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Results |
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No myocardial recovery occurred after MCS implantation. In 5 patients profound multiorgan failure occurred despite adequate circulatory support and they died after a median period of 2 days (range, 2 to 17). In 7 patients circulatory support led to recovery of organ function and the patients were judged to be candidates for long-term support. The conversion to BerlinHeart was performed after a median period of 6 days (range, 2 to 13). Six of them were weaned from the ventilator and survived for more than 30 days.
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Comment |
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Profound acute cardiogenic shock continues to occur in 2% to 6% of cardiac surgical patients and is an important issue for patients with acute myocardial infarction or acute myocarditis. Clinical experience shows the importance of appropriate patient selection and early MCS implantation in these patients [1, 2]. However the most challenging issue concerning short-term MCS is the inability to predict sustained myocardial recovery and recovery of organ function. Approximately 50% of patients requiring short-term MCS are suitable candidates for long-term support. However, bleeding infections and multiorgan failure are major complications in patients after MCS implantation [2, 6–9]. The conventional technique for conversion to long-term support in these patients involves repeated sternotomy and the use of CPB with subsequently increased risk for infection. Exchange of the cannulas causes additional trauma of the fragile myocardium with increased risk for bleeding. Avoiding these procedures by using the approach presented may therefore lead to significant reduction of life-threatening postoperative complications [8]. Furthermore the larger size of the BerlinHeart inflow cannulas increases blood flow up to 6 L/min provided by the Abiomed device.
Appropriate timing is important for the decision-making process. In all patients myocardial recovery should be assessed daily and the decision on further treatment taken in the first 10 days to reduce the risk of thrombosis of the Abiomed pump with subsequent need for exchange [2].
High costs are the other major concern in the use of MCS. Although the cannulas and pumps of the BerlinHeart device are more expensive than those of Abiomed our analysis showed a significant cost reduction if the new approach was used, while the risk from surgery was reduced and the outcome improved. The additional costs for patients who died result from the use of BerlinHeart instead of Abiomed cannulas. However, in patients in whom the Abiomed pumps are exchanged for Berlin Heart pumps more costs are saved by avoiding a repeat surgical procedure to exchange cannulas. These include the cost of the operating room, CPB use, and additional personnel and equipment. Furthermore this approach could be applied in nontransplanting centers or those using Thoratec VAD cannulas (L. Samuels, M. Loebe, personal communications) with an option for subsequent transfer to a hub center where the conversion to a long-term assist device can be performed [1]. In addition the approach also allows implantation of a left ventricular support system using a left thoracotomy in patients with a previous median sternotomy [10].
The presented approach is suitable for emergency procedures but it should be avoided if fast myocardial recovery is not expected (eg, unsuccessful surgical procedure or chronic heart failure), if the patient primarily fulfilled the criteria for an implantable left ventricular assist device (Novacor, TCI, DeBakey VAD), or if the implantable device is scheduled for use as a long-term support in a second step [1].
We believe that the approach presented leads to decreased risk for infection and bleeding, faster recovery of patients, and significant reduction of costs. Furthermore, this approach could be established in nontransplanting centers and the use of cannulas from other extracorporeal devices (Thoratec) could be taken into consideration.
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References |
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This article has been cited by other articles:
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  C. Stamm, B. Nasseri, and R. Hetzer Rescue versus regeneration. J. Thorac. Cardiovasc. Surg., October 1, 2007; 134(4): 1095 - 1096. [Full Text] [PDF]
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D. Loisance Mechanical circulatory support systems--future opportunities Eur. J. Cardiothorac. Surg., December 1, 2004; 26(Suppl_1): S48 - S53. [Abstract] [Full Text] [PDF]
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