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Ann Thorac Surg 2004;77:1428-1430
© 2004 The Society of Thoracic Surgeons

Case report

Transcontinental transport of a patient with an AbioMed BVS 5000 BVAD

Evgenij V. Potapov, MDa*, Frank Merkle, ECCPa, Andreas Güttel, RNa, Miralem Pasic, MD, PhDa, Michael Caleb, MDb, Michael Kopitz, ECCPa, Roland Hetzer, MD, PhDa

a Deutsches Herzzentrum Berlin, Berlin, Germany
b National Heart Center Singapore, Singapore

Accepted for publication May 2, 2003.

* Address reprint requests to Dr Potapov, Deutsches Herzzentrum Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
e-mail: potapov{at}dhzb.de


   Abstract
Top
 Abstract
Introduction
 Comment
 Acknowledgments
 References
 
In patients with severe cardiogenic shock requiring implantation of a short-term assist device transportation to a specialized heart center for further therapy may be necessary. We report the first successful transcontinental air transport (from Singapore to Berlin, Germany) of a patient with fulminating myocarditis requiring implantation of a biventricular assist device.


   Introduction
Top
 Abstract
 Introduction
Comment
 Acknowledgments
 References
 
In some cases of acute cardiogenic shock only mechanical circulatory support can keep the patient alive. Some patients require transport from the local hospital where the device was implanted to a hub hospital for further treatment. Experience with airborne transport of such patients is limited. The present case indicates progress in managing patients on mechanical circulatory support.

A German tourist with no past history of heart disease was admitted to Changi General Hospital in Singapore after arriving from Australia where he was on vacation with his family. He was 59 years old and weighed 110 kg. He complained of decreased effort tolerance for 2 days before arrival and shortness of breath. He was found to be extremely tachypneic with atrial flutter and a heart rate of 150 bpm. He was intubated for respiratory distress. The patient became hemodynamically unstable, requiring intravenous inotropic agents and intraaortic balloon pump support. Echocardiography showed extremely poor global cardiac function with a left ventricular ejection fraction of 0.10 and right ventricular ejection fraction of 0.30. A coronary angiogram revealed normal coronaries. He was also pyrexial with elevated white blood cells. Fulminant myocarditis was diagnosed and the patient was transferred to the National Heart Center in Singapore 5 days later. At this time he presented liver congestion (ALT 847 U/L, AST 550 U/L) with hyperbilirubinemia (57 mmol/L).

Immediately after admission he underwent implantation of an AbioMed BVS 5000 cardiac assist device as a left ventricular support using a left atrial cannula. Initially he made an uneventful recovery but 6 days postoperatively he developed progressive low cardiac output despite use of inhaled nitric oxide due to right ventricular failure and bronchopneumonia requiring right ventricular assist device placement. His surgeon (M.C.) contacted the Deutsches Herzzentrum Berlin with a request to transfer the patient back to Germany.

After the Swiss air rescue company (Rega, Schweizerische Flugwacht, Switzerland) was contacted by the travel insurance company and a specially equipped ambulance aircraft Canadair Challenger 604 was organized, a team from the Deutsches Herzzentrum Berlin consisting of an experienced cardiac surgeon (E.P.), an intensive care nurse (A.G.), and a perfusionist (F.M.) started to prepare the transport. In addition to the usual intensive care equipment, a hand pump from the BerlinHeart assist device (BerlinHeart AG, Berlin Germany), modified for connection with the AbioMed driving lines with 1/4-inch polycarbonate tubing connectors, and an AbioMed BVS 5000i console were also prepared for the transport. The aircraft was checked for a 230 V AC power source in sinus wave form. While the medical team flew to Singapore, the patient underwent reexploration for pericardial tamponade and 4 hours later for bleeding from a right chest tube. Upon arrival of our team at the hospital the patient was alert and mechanically ventilated with FiO2 of 0.7 and a pump flow of 5 L/min. The patient required norepinephrine 0.07 µg/kg body weight per minute; his urine output was between 100 and 200 mL/h; he showed no acidosis; and the bleeding from the right chest tube was between 100 and 150 mL/h. However, the platelet count dropped below 70,000/µL and the enzyme-linked immunosorbent assay test for heparin-induced thrombocytopenia type II (HIT II) repeated twice showed positive results each time.

The transport from the hospital to the airport was performed using the AbioMed 5000t transport console powered by 230 AC from an external battery employing a DC/AC converter. The blood pumps were placed in the horizontal position for easier handling. In this position, negative pressure is required to fill the pump chamber completely. The transfer from the ambulance into the aircraft (and later from the aircraft into the ambulance in Berlin) was performed using the modified hand pump from the BerlinHeart ventricular assist device (VAD) (Fig 1). After the patient was positioned in the aircraft, the blood pumps were placed upright and then the driving lines were connected to the AbioMed BVS 5000i console, which remained in the aircraft, while the AbioMed BVS 5000t console was used as a backup during the flight.



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  		Fig 1. Transfer of the patient from the aircraft into an ambulance after arrival in Berlin. Perfusionist (1) driving both blood pumps using a modified hand pump. The blood pumps are secured by the second perfusionist (2).

 
The aircraft flew at an altitude of 40,000 feet with the cabin pressure equivalent to 8,000 feet. The flight duration was 15.5 hours with one stopover in Oman for refueling; altogether the journey lasted 19 hours. During the flight the pump flow decreased to 4 L/min with subsequent increase of the norepinephrine doses from 0.16 to 0.22 µg/kg body weight per minute. At sea level the pump flow increased again to up to 5 L/min with subsequent decrease of the norepinephrine doses to 0.16 µg/kg body weight per minute. The peripheral O2 saturation decreased during the flight from 99% to 96%, while the respirator setting and the FiO2 remained unchanged. The patient received assisted ventilations and was alert during the transport under low doses of sufentanil (10 µg/h). No medical problems occurred except continued bleeding of 150 mL/h from the right chest tube requiring transfusion of 6 U packed red blood cells and 4 U fresh frozen plasma, which were stored in the aircraft's refrigerator at 4°C. The activated clotting time (ACT), blood gases and electrolytes were checked every 2 hours during the flight using portable devices and the ACT maintained between 160 and 180 seconds using continuous infusion of heparin.

After arriving at the Deutsches Herzzentrum Berlin, the patient underwent a switch to the BerlinHeart extracorporeal BVAD (M.P.). After rethoracotomy and evacuation of 1500 mL blood from the pericardium and 500 mL from the right pleural space, cardiopulmonary bypass was established in the usual manner and the left atrial cannula was exchanged for the BerlinHeart apical cannula. The right atrial cannula was also exchanged because of bleeding from the anastomosis. The anastomoses of the aortic and pulmonary artery AbioMed cannulas were successful and were left in situ because of the fragility of the tissue around the anastomoses. After the left pump (80 mL stroke volume) and the right pump (60 mL stroke volume) were connected, the drive pressure through the AbioMed cannulas was measured and found not to be elevated.

The postoperative course was uneventful. The echocardiographic evaluation during pump stop 2 months after surgery showed improvement of the left ventricular ejection fraction to 0.50 and of the right ventricular ejection fraction to 0.60. The left ventricular end-diastolic dimension decreased to 54 mm. The VAD was explanted and the patient discharged home.


   Comment
Top
 Abstract
 Introduction
 Comment
Acknowledgments
 References
 
The AbioMed BVS 5000 is a reliable short-term VAD, which can be easily implanted and provides sufficient circulatory support. The device can be used as a bridge to recovery or as a bridge to a bridge [1]. If the device is implanted in a nontransplanting center or as in the present case in a patient from a foreign country, transportation to another hospital for further therapy may be necessary. Although ground and air transport using the AbioMed 5000t console has been described previously, transcontinental air transport for as long as 15.5 hours of a severely ill patient with an AbioMed BVAD is very unusual.

Some critical points of this transport deserve discussion. The most difficult part was maneuvering the patient in and out of the aircraft without damaging the extracorporeal blood pumps. For this purpose, we hung the AbioMed blood pumps in a horizontal position in the transparent sling mount pockets about 10 inches below the heart. In this position, a vacuum is needed to completely fill the AbioMed ventricles. The vacuum was provided by the modified BerlinHeart hand pump. This hand pump consists of a cylinder with a piston that can be activated by a hand piece (similar to a bicycle pump). The cylinder has two connectors to the pump driving lines, one at each end. The piston thus alternately compresses one ventricle, while evacuating the other. A pump rate of 80/min was sufficient to generate a mean arterial pressure of 70 mm Hg.

In the aircraft the distance of 80 cm between the upper edge of the mattress and the floor allowed the use of the AbioMed BVS 5000i console. The console, powered by 230 V AC during the flight, provided successful drive pressure, while the gravity drainage of both pumps was excellent. However at cabin pressure equivalent to 8,000 feet the flow decreased from 5 to 4 L/min. This decreased flow was compensated by volume replacement and increase of norepinephrine doses; the patient tolerated this situation well for several hours. We have no explanation for this phenomenon. In more critical situations we would recommend flight at sea level cabin pressure, bearing in mind that the peripheral oxygen saturation also decreased. The advantage of flying at an altitude of 40,000 feet but with cabin pressure equal to that at 8,000 feet was that the flight was approximately 3 hours shorter and one less stopover for refueling was required. However, the air humidity at this altitude is approximately 5% and permanent volume replacement during such a long flight is crucial for adequate pump and renal function.

Bleeding after implantation of an assist device is one of the major complications. It is therefore obligatory during such a transcontinental flight to carry appropriate amounts of blood products as well as the equipment for an emergency thoracotomy in case cardiac tamponade should occur. In the presented case HIT II was suspected based on results from the enzyme-linked immunosorbent assay test, which was assumed to have 50% false-positive results. We discussed the use of hirudin as an alternative to heparin, but decided against it because hirudin would have been associated with an undetermined amount of time for the switch in the absence of ecarin clotting time measurement in the local hospital, because of the impossibility of sufficient monitoring of anticoagulation status during the flight, and because of a potentially unpredictable situation in the case of impairment of renal function during transport. Additionally, because of stable platelet count under platelet substitution, absence of clinical signs of HIT II, and continued bleeding from the right chest tube, we decided to use intravenous heparin for better anticoagulation control during the flight using an ACT device.

The rationale for the switch to BerlinHeart was the need for long-term support, which is not possible using the AbioMed system, and, most importantly, the opportunity to use the BerlinHeart apical cannula, which allows complete unloading of the left ventricle; this strategy is crucially important for myocardial recovery in patients with fulminant myocarditis. In the present case myocardial recovery occurred only 3 weeks after mechanical unloading and myocardial function continued to improve during support, leading to successful explantation of the BVAD 2 months after surgery.

The transport costs were approximately US $140,000 for the ambulance aircraft and approximately US $10,000 for the team, covered in full by the travel insurance of the patient.

In conclusion, the transcontinental transport of a critically ill patient with an AbioMed BVAD by experienced personnel using a special ambulance aircraft can be performed safely and in some cases may be the only possibility to provide adequate treatment. Use of the apical cannula is of crucial importance for myocardial recovery in patients with acute myocarditis.


   Acknowledgments
Top
 Abstract
 Introduction
 Comment
 Acknowledgments
References
 
We thank Diana Kendall for ground management of the transport; the surgical team and the transport ambulance in Singapore for excellent management of the patient and transfer from hospital to the airport; and the pilots and flying nurse of Rega Swiss AirRescue for a smooth flight and optimal medical assistance. Additionally, we thank David Holt, CCP, from Ohio State University for expert advice on the transportation of patients on an AbioMed BVS 5000 assist device, and Anne Gale for editorial assistance. We also thank AbioMed, Inc, for providing technical support.


   References
Top
 Abstract
 Introduction
 Comment
 Acknowledgments
 References
 

  1. Samuels L.E., Holmes E.C., Thomas M.P., et al. Management of acute cardiac failure with mechanical assist: experience with the ABIOMED BVS 5000. Ann Thorac Surg 2001;71(Suppl):S67-72.[Abstract/Free Full Text]



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