Ann Thorac Surg 2007;83:298-300
© 2007 The Society of Thoracic Surgeons
Case Reports
Bi-Ventricular Circulatory Support With the Abiomed AB5000 System in a Patient With Idiopathic Refractory Ventricular Fibrillation
Li Zhang, MD, MSa,*,
Emmanouil I. Kapetanakis, MDa,
Richard H. Cooke, MDb,
Leslie C. Sweet, RNa,
Steven W. Boyce, MDa
a Section of Cardiac Surgery, Department of Surgery, Washington Hospital Center, Washington DC
b Division of Cardiology, Department of Internal Medicine, Washington Hospital Center, Washington DC
Accepted for publication May 10, 2006.
* Address correspondence to Dr Zhang, Section of Cardiac Surgery, Department of Surgery, Washington Hospital Center, 110 Irving St, NW, Washington, DC 20010-2975 (Email: li.zhang{at}medstar.net).
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Abstract
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A 45-year-old man had life-threatening recurrent idiopathic ventricular fibrillation and persistent cardiogenic shock develop. The episodes of ventricular fibrillation were refractory to aggressive medical management; therefore an Abiomed AB5000 bi-ventricular support system was implanted for arrhythmia control. The device was able to maintain hemodynamic stability during the following 2 weeks. The patient was discharged from the hospital with fully recovered cardiac function.
Ventricular fibrillation (VF) is the most frequent cause of out-of-hospital cardiac arrest [1]. A number of relatively young, otherwise healthy patients may have idiopathic refractory VF develop, which leads to a high mortality. However the development of safe and reliable mechanical support devices is now providing a new modality for refractory VF while planning definitive anti-arrhythmic therapy. This report describes the case of a patient with idiopathic, refractory ventricular fibrillation who was successfully resuscitated with the new Abiomed AB5000 bi-ventricular assist device (BiVAD) system (Abiomed Inc, Danvers, MA).
While visiting Washington, DC, a 45-year-old, previously healthy Caucasian male experienced multiple syncopal episodes within 2 hours of being admitted to a local hospital. He was initially found to have a wide complex tachycardia. Although medical therapy was initiated, he had ventricular tachycardia, fibrillation, and cardiac arrest develop, which required multiple resuscitations with electrical cardioversion. Electrocardiogram and laboratory tests did not show evidence of myocardial ischemia or infarction. Emergent cardiac catheterization did not demonstrate appreciable coronary artery disease. Drug abuse and toxication were also excluded. Despite multiple electrical cardioversions and continuous anti-arrhythmic therapy, his rhythm and hemodynamics remained unstable. His left ventricular ejection fraction deteriorated from 30% to less than 10% in about 6 hours. He was transferred to our institution for further management.
On arrival the patient was in cardiogenic shock, in spite of intraaortic balloon pump and inotropic support. The patient was immediately taken to the operating room where an Abiomed AB5000 BiVAD (Abiomed Inc, Danvers, MA) was inserted (Fig 1). The left circuit was established using a 32-French inflow cannula from the left ventricular apex, which allowed maximal unloading of the left ventricle, and a 10-mm outflow graft to the ascending aorta (Fig 2). To provide flow to the right prosthetic ventricle, a 42-French cannula was inserted into the right atrium, and a 10-mm outflow graft was anastomosed to the pulmonary artery (Fig 2). Intraoperative transesophageal echocardiography revealed a small patent foramen ovale, which was closed with a running suture. Total bypass time was 68 minutes. Bi-ventricular assist device flow ranged from 3.6 to 4.5 L/min, which allowed successful weaning of the patient from cardiopulmonary bypass with minimal need for inotropic agents. Intraaortic balloon pump was removed and the patient was transferred to the intensive care unit with stable hemodynamics and normal cardiac electrical activity. The AB5000 BiVAD functioned consistently, and the patient remained hemodynamically stable. Prophylactic amiodarone was continued through discharge. The right ventricular assist device was successfully removed on the seventh postoperative day, followed by the removal of the left ventricular assist device (LVAD) a week later. Follow-up echocardiography showed normal left and right ventricular contractility. An implantable cardioverter defibrillator (ICD) was placed despite a negative electrophysiology study on a maintenance dosage of amiodarone. The patient was discharged from hospital on the 35th postoperative day. He is now at 2 years post-discharge and has returned to all normal activity.
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Fig 2. Illustration showing paracorporeal placement of the AB5000 prosthetic ventricles (Abiomed Inc, Danvers, MA) for bi-ventricular support.
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Most of out-of-hospital cardiac arrests are attributable to VF or rapid ventricular tachycardia (VT). As much as 15% of VT and 10% of VF can occur in patients without detectable myocardial abnormalities. These patients are at relatively high risk for sudden cardiac death. In patients with idiopathic ventricular arrhythmia, prognosis relies on arrhythmic control. The standard management of ventricular arrhythmia consists of medical therapy and electrical cardioversion or defibrillation. When these measures fail to restore or maintain sinus rhythm, mechanical cardiac support becomes a useful tool to stabilize the patient before definitive therapy can be achieved. One of the most crucial effects of mechanical cardiac support is to restore myocardial perfusion and reduce myocardial wall tension by unloading the ventricles, thus decreasing oxygen demand and subsequent subendocardial ischemia.
Experience from different groups proved that patients could tolerate life-threatening ventricular arrhythmias very well after implantation of a ventricular assist device. In 1994, Oz and colleagues [2] reported that the Heartmate Left Ventricular Assist System (Thoratec Laboratories, Berkeley, CA) was effective in supporting patients with malignant ventricular arrhythmias lasting from 10 minutes to 12 days.
Since the early 1990s, mechanical circulatory assist systems have been successfully used as an adjunct therapy for refractory ventricular arrhythmia so as to maintain hemodynamic stability while undergoing definitive anti-arrhythmic therapy. The Thoratec LVAD (Thoratec Laboratories, Berkeley, CA) and the Abiomed BVS5000 LVAD (Abiomed Inc, Danvers, MA) have been used for circulatory support in patients with refractory ventricular tachycardia [3, 4]. Theoretically, however, only bi-ventricular support is able to unload both ventricles simultaneously, especially in the case of VF. In an experimental study on intractable VF, Tukkie and colleagues [5] revealed that the successful rate of defibrillation increased from 36% to 100% when placed on the BiVAD. Subsequently, Farrar and colleagues [6] reported promising results after using the Thoratec bi-ventricular support as a bridge to transplantation in 6 patients with potentially lethal arrhythmias. More recently, Fasseas and co-authors [7] described using the Abiomed BVS5000 BiVAD to stabilize a patient with refractory ventricular arrhythmia. The patient was successfully weaned from the assist device. By contrast, in another patient with VT and VF, LVAD alone failed to maintain hemodynamic stability until sinus rhythm was restored after numerous attempts of cardioversion and implantation of an implantable cardioverter defibrillator. Bi-ventricular assist devices provide complete circulatory support during the period of VF and asystole, and although they do not convert the arrhythmia directly, BiVADs provide a therapeutic window and a bridge to recovery. In the American College of Cardiology statement published in 2001, uncontrollable ventricular arrhythmia was listed as one of the indications for mechanical cardiac support [8].
Among the approved Food and Drug Administration cardiac assist devices, only the Abiomed and Thoratec devices can provide bi-ventricular support. In our patient we implanted the Abiomed AB5000, which consists of a fully automated, vacuum-assisted control console and a paracorporeal, volume-displacement pump that is pneumatically driven. In contrast to its predecessor, the BVS5000, the AB5000 is designed for longer duration and allows for patient ambulation. Although only a limited number of AB5000 devices have been implanted to date, they seem to be a reliable and safe successor of the BVS5000.
In conclusion, aggressive use of mechanical cardiac support is crucial to improve outcome and recovery in patients with hemodynamic compromise due to cardiac arrhythmia.
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Acknowledgments
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We would like to thank David Hayes for his descriptive illustration.
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References
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