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J Thorac Cardiovasc Surg 2004;128:643-645
© 2004 The American Association for Thoracic Surgery
Brief communication |
a Lankenau Hospital, Department of Cardiothoracic Surgery, Wynnewood, Pennsylvania, USA
b Drexel University, Hahnemann University Hospital, Department of Cardiothoracic Surgery, Philadelphia, Pennsylvania, USA
Received for publication July 24, 2003; accepted for publication March 31, 2004.
* Address for reprints: Louis E. Samuels, MD, Lankenau Hospital, Department of Cardiothoracic Surgery, MSB Suite 280, 100 Lancaster Avenue, Wynnewood, PA 19096, USA
SamuelsLE{at}aol.com
| Because of a potential conflict of interest related to this article on the part of our editors, Dr Robert L. Kormos served as guest editor, assigned reviewers, and made editorial decisions or recommendations leading to its acceptance for publication.
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Fixed pulmonary hypertension is a contraindication for orthotopic heart transplantation.1 The AbioCor artificial heart (Abiomed Inc, Danvers, Mass) was designed as a totally internal replacement system for patients with end-stage heart failure who are not eligible for heart transplantation. The purpose of this report is to describe the experience with the AbioCor artificial heart in the setting of a patient with severe biventricular failure and irreversible pulmonary hypertension.
Clinical summary
A 51-year-old, 5-foot 9-inch, 170-pound (body surface area 1.9 m2) man with idiopathic dilated cardiomyopathy presented with progressive shortness of breath and fatigue. His medical history was significant for emphysema and hepatitis B and C viruses. Medications included oral digoxin, hydrazlazine, bumetanide, and fosinopril. Intravenous therapy included dobutamine 10 µg · kg · min and milrinone 0.50 µg · kg · min.
Cardiac evaluation showed normal sinus rhythm with left atrial enlargement, 4-chamber cardiac dilatation, severe global biventricular dysfunction, moderate tricuspid and severe mitral regurgitation, and pulmonary hypertension. Left and right heart catheterization showed normal coronary arteries with elevated pulmonary artery (69/37 mm Hg), central venous (18 mm Hg), and pulmonary capillary wedge (25 mm Hg) pressures. The thermodilution cardiac output was 3.3 L/min with an adjusted cardiac index of 1.7 L · min · m2. The pulmonary vascular resistance was 7.8 Wood units. Pharmacologic maneuvers to reduce the pulmonary vascular resistance with nitroglycerin and nitroprusside were unsuccessful. Stress testing showed a peak oxygen consumption (VO2 max) of 8.3 mL · kg · min. The estimated ejection fraction was 15%.
Significant laboratory abnormalities included hyponatremia, hypokalemia, and elevated norepinephrine levels. Chest radiography demonstrated hyperinflated lungs and massive cardiomegaly. Pulmonary function studies showed a moderate obstructive pattern on spirometry.
The patient was reviewed by the transplant committee and deemed ineligible on the basis of fixed pulmonary hypertension and comorbidities. He was referred for AbioCor artificial heart trial consideration. The patient agreed to the study and signed the consent form accordingly. The AbioFit was performed and found to be adequate. The AbioScore predicted a 30-day mortality of 75%.
On November 1, 2001, the patient was admitted to Hahnemann University Hospital with decompensated heart failure. The dobutamine infusion was increased to 15 µg · kg · min, and the milrinone was increased to 0.75 µg · kg · min. On November 5, 2001, the AbioCor device was implanted. Hemodynamics before implantation under general anesthesia were unchanged from those observed in the outpatient clinic (Fig 1). The surgical technique was performed according to protocol, with attachment of the Dacron atrial cuffs to the fibrous skeleton of the atrioventricular valve annuli. The patient was separated from cardiopulmonary bypass after approximately 3.5 hours, with proper pump function and satisfactory hemodynamics (Fig 2). No blood transfusions were required. Transesophageal echocardiography demonstrated no systemic or pulmonary venous inflow obstruction.
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As an outpatient, the patient was able to participate in many activities, including excursions to church, movies, restaurants, bingo, neighborhood activities, and parties. However, after approximately 3 weeks, his pulmonary condition and oxygen requirements increased, with concomitant elevation of the pump's RHPs and development of prominent interstitial lung markings and pleural effusions on chest radiography. He was readmitted for further investigation.
Operative drainage was required for the relief of serosanguineous pleural effusions. The development of hemoptysis required frequent bronchoscopy and reduction (with eventual cessation) of anticoagulation. His pulmonary condition progressed to ventilator dependence requiring tracheostomy. After several months of support, he was eventually weaned from the ventilator. He was being prepared for discharge when he had a massive stroke on postoperative day 293. The AbioCor device was discontinued, and the patient died. Autopsy findings showed significant emphysema and pulmonary vascular changes consistent with longstanding and severe pulmonary hypertension. There was no obvious evidence of pulmonary emboli on the limited autopsy. Examination of the device showed minor thrombi on the valve leaflets.
Discussion
The AbioCor replacement heart was approved by the Food and Drug Administration for clinical trial in January 2001. The first clinical implant was performed on July 2, 2001, at the Jewish Hospital, Louisville, Kentucky, with subsequent implants performed at 4 centers in the United States.2 Patient selection consists of nontransplant candidates with end-stage biventricular failure on maximal medical therapy whose life expectancy is predicted to be less than 30 days. As such, patients with advanced age, comorbidities with end-organ damage, cancer, and systemic conditions (eg, amyloid) are potential candidates. In addition, patients with elevated and fixed pulmonary hypertension are considered eligible candidates for AbioCor device screening.
The AbioCor is the only device that is a total heart replacement system designed for permanent therapy.3 Other systems, all left ventricular assist devices, are being considered for this purpose.4 The role of permanent total heart replacement in the setting of fixed pulmonary hypertension, therefore, is novel, because the pump will continue to generate physiologic flow in the milieu of a pathologic pulmonary bed. This unnatural condition may exacerbate underlying pulmonary disease. As demonstrated in this case, the patient had immediate pulmonary complications necessitating ECMO support. The cause was never elucidated, and the condition resolved after 3 days. Theories regarding the cause include a capillary leak type syndrome from the effects of augmented pulmonary blood flow provided by the pump in the setting of a "stiff" pulmonary vascular system. Alternatively, temporary pulmonary venous obstruction caused by the active fill mechanism of the device may have resulted in transient but extreme pulmonary venous congestion. A similar but less dramatic form of this syndrome was observed in another recipient (personal communication). In the case presented, the patient's respiratory condition initially improved to a state superior to his preoperative condition at approximately 1 month. His overall health continued to improve during the second month, at which time he was discharged. Shortly thereafter, his pulmonary status gradually deteriorated, requiring rehospitalization and intubation. Again, the cause of this deterioration was unclear. Hemoptysis was an ever-present condition on his readmission and only ceased with discontinuation of anticoagulation and antiplatelet therapy. Attempts to avoid pressure-related causes for the hemoptysis were made by adjusting the pump output. The attempt was to reduce the pump's flow and facilitate a reduction in the RHP, indicating a decrease in the pulmonary artery pressure. A Swan-Ganz catheter (Edwards LifeSciences, Irvine, Calif) was inserted to confirm the accuracy and correlation of the RHP measurements. These maneuvers, and the use of nitric oxide, were unsuccessful. For several weeks during the ventilator support, the RHP remained elevated, and measurements were nearly systemic at times. After cessation of the hemoptysis and aggressive nutritional support, the patient was eventually weaned from ventilator support but had a massive stroke at nearly 10 months.
Conclusion
The AbioCor replacement heart supported the circulation in a patient with end-stage biventricular heart failure with fixed pulmonary hypertension for 293 days. There were no device malfunctions. Physiologic flows permitted activities that exceeded the preoperative state for several months. Pulmonary-related complications developed in the immediate postoperative period and resolved. Respiratory failure redeveloped at 2 months and persisted. The unnatural history of fixed pulmonary hypertension in the setting of a total heart replacement system remains an entity of uncertainty. Further studies will be necessary to determine whether fixed pulmonary hypertension is an indication or contraindication to destination therapy with a total heart replacement system.
References
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